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Goal directed fluid therapy. What works?

Normal saline versus a balanced crystalloid for goal-directed perioperative fluid therapy in major abdominal surgery: a double-blind randomised controlled study

British Journal of Anaesthesia 2018;120(2):274-283

Presented by: Dr I Rees

Background

  • Normal saline 0.9% amongst most commonly used crystalloid for fluid therapy
  • However normal saline not ‘normal’
    • Sodium and chloride concentrations 154mmol/l
    • Risk of hyperchloraemic metabolic acidosis and reduced anion gap
    • Linked to increased risk of renal dysfunction, transfusion and mortality in patients undergoing abdominal surgery
  • Balanced crystalloids contain metabolisable anions (lactate or acetate)
    • Maintain electrolyte stability
    • Less associated with metabolic acidosis
    • Metabolised to bicarbonate
  • Recent study in same centre demonstrated patients undergoing cadaveric renal transplantation required significantly less catecholamine support if receiving balanced crystalloid, compared to the group receiving normal saline
  • Authors hypothesised that patients undergoing major surgery might require less vasopressor support if they received a balanced crystalloid, as opposed to normal saline perioperatively

Design & Setting

  • Single-centre (Department of Anaesthesiology of the Medical University of Vienna, Austria)
  • Prospective double-blinded randomised controlled study of patients undergoing elective major abdominal surgery
  • Patients and anaesthetists blinded
  • Ethics approved
  • Sample size calculated (based on previous transplantation study) – 120 patients per group (240 total) to give α 5% and 80% power

Subjects

Inclusion criteria:

  1. Adult, non-pregnant patients
  2. Undergoing elective major abdominal surgery (any general, gynaecological or urological procedure requiring laparotomy)

Exclusion criteria:

  1. LV ejection fraction <30%
  2. Renal dysfunction (GFR <30ml/min) and severe liver disease
  3. Chronic inflammatory diseases requiring long-term steroids
  4. Pre-operative sepsis or critical care patients
  5. Contraindications to oesophageal doppler
  6. Intraoperative epidural analgesia

Intervention

  • Patients randomised on day of surgery to receive either normal saline or a chloride-reduced acetate-buffered balanced crystalloid (Elomel Isoton)
  • No pre-operative fluid infusion
  • Blinded fluids given to anaesthetist before induction of anaesthesia
  • Standardised anaesthetic:
    • Standardised induction (propofol 2-3mg/kg, rocuronium 0.6mg/kg and fentanyl 2-3mcg/kg)
    • Standard monitoring including arterial line and CVP + depth of anaesthesia monitoring (Narcotrend), train-of-four ulnar montoring and oesophageal doppler (CardioQ)
    • Sevoflurane administration according to Narcotrend; FiO2and fentanyl boluses according to clinical requirement; Rocuronium to maintain one or two twitches on TOF
    • Ventilation to maintain end-tidal CO2 near 35mmHg (~4.6kPa) – tidal volume 8-10ml/kg (LBW), peak pressure <30mmHg (~40cmH2O) and PEEP of 5mmHg (~7cmH2O) or higher according to patient need.
    • Temperature >36oC using forced air warmer and hourly arterial blood gases
    • Fluid maintenance 2ml/kg/hr (IBW as per Robinson’s formula) increased to 5ml/kg/hr on exposure of viscera
  • Target MAP according to pre-operative blood pressure the day before surgery:
Pre-operative Blood Pressure (mmHg) Intraoperative Target MAP (mmHg)
Hypotensive SBP <120 60
Normotensive SBP 120-139 / DBP 80-89 70
Hypertensive SBP >140 / DBP >90 80
  • If MAP fell, standardised protocol followed:
    • SV responsiveness assessed using 250ml fluid challenge
    • If >10% increase in SV but MAP still below desired value, further 250ml boluses until SV increase <10% or target MAP achieved
    • If target MAP still not achieved and SV ‘unresponsive’, phenylephrine 0.1-0.2mcg bolus given (maximum 0.8mcg/hr)
    • If still insufficient, noradrenaline infusion started at 0.01-0.02 mcg/kg/min and titrated to desired MAP by increments of 0.05-0.1mcg/kg
    • If SV fell by >10% of the value following the last fluid challenge, a further 250ml was given
    • Noradrenaline titrated down or stopped if fluid challenges sufficient in maintaining MAP
  • Exit criteria: pH below 7.2, bicarbonate below 14mmol/l, base excess below -10mmol/l or response to catecholamines insufficient – fluid changed to balanced crystalloid and study was terminated.

Outcomes

Primary:

  1. Need for vasopressors

Secondary:

  1. Total dose of catecholamines
  2. Total perioperative fluid
  3. Unplanned intensive care admissions

Results

  • Terminated early for safety reasons (hyperchloraemic metabolic acidosis) after discussion with study safety board and local authority
  • Only 60 of the total planned 240 were studied (30 in each group)
  • More patients required vasopressors in the normal saline group than the balanced crystalloid (97% vs67% respectively,p=0.033)
  • Median weight and duration-adjusted dose of norepinephrine were 0.11(0.00-0.45)mcg/kg/min in the normal saline group compared with 0.00mcg/kg/min in the balanced crystalloid group (p=0.003)
  • No difference between groups in total perioperative fluid and unplanned intensive care admissions
  • Cox regression showed need for vasopressors related to high volume of administered fluid, normal saline resuscitation and lower MAP

Conclusions

  • Study suggests that patients undergoing major abdominal surgery with normal saline fluid therapy have a significantly larger vasopressor requirement than those receiving a more physiological crystalloid.
  • Hyperchloraemia with or without acidosis may be a direct trigger for unfavourable cardiovascular effects – leads to increased nitric oxide, as seen in rats

Strengths

  • Focused question asked
  • Hypothesis based on previous study
  • Prospective double-blinded RCT
  • Patient groups comparable
  • Appropriate inclusion and exclusion criteria
  • Extremely standardised protocol
  • Appropriate statistical analysis i.e. Mann-Whitney U Test for quantitative, non-parametric analysis of 2 unpaired groups

Weaknesses

  • Terminated due to patient safety
  • Underpowered (67%) for primary outcome due to low numbers – power 90% for secondary outcomes
  • Single-centre
  • Protocol resulted in large amounts of intraoperative fluid infusion (median 3427ml of normal saline and 3144 of the balanced crystalloid)
  • No mention of blood products
  • No epidural or intrathecal block
  • Is it an important clinical question?

Implications/Potential for impact

  • Is our practice likely to change following this study?
  • Inference that normal saline may cause detrimental cardiovascular effects due to hyperchloraemic acidosis (leading to increased nitric oxide, as seen in rats) is interesting
  • Vast majority of anaesthetists likely to use a balanced crystalloid e.g Hartmann’s solution, rather than normal saline for elective adult surgery (save for a few circumstances e.g. liver failure etc) as it is more ‘physiological’ – why cause further stress during the stress response?

Following this underpowered study that put patients in harm’s way, I will do as the authors suggest i.e. exactly what I’ve been doing this entire time.

January 2018

Written by Dr C. Williams

Sexual harassment in medicine – #MeToo. Jagsi R. New England Journal of Medicine 2017 doi:10.1056/NEJMp1715962

This is a short but highly interesting article looking at the phenomenon of sexual harassment in medicine. Currently it seems that not a week passes without the media filled with news of celebrities engaged in sexual misconduct. This article is written by a medical academic who has led a study of workplace sexual harassment in medicine. She describes the numerous incidents reported to her of sexual harassment in medicine and how victims often do not report incidents and the ones that do experience marginalisation, retaliation, stigmatisation and worse. Despite the #MeToo movement, reporting such behaviour is still not straightforward.

But what is sexual harassment. Working in an operating theatre still seems to be a male dominated environment and often an environment where lewd ‘locker-room’ humour dominates. But at what point does this humour cross the line into sexual harassment? One only has to have a few conversations with other healthcare professionals to start to hear stories, often told in jest, of incidences that clearly cross this line. I too have multiple stories which when looking at them objectively are clearly examples of unacceptable behaviour. I was relating one such experience to a colleague as a humorous story (which it was – although not so much at the time). I was asked to formally report the event……..but I didn’t, for several reasons, not least the concern that it would effectively be career suicide. This is also touched upon in the article.

This article concentrates on females being subjected to sexual harassment. But females aren’t the only ones affected. I have witnessed a male colleague being harassed by a bay of 80-plus year old female patients. If the situation had been reversed then I suspect there may have been a different attitude to the event by the female nursing witnesses.

The article mentions an interesting concept devised by academic astronomers. They recognised that mandatory reporting dissuades people so developed a rescue system, or a list of ‘astronomy allies’. These are senior female astronomers who wear prominent buttons at national society meetings and make themselves available to remove colleagues from problematic situations (www.astronomyallies.com). The aim is to provide ‘judgement-free’ help if someone believes it is needed. As the author points out, it raises questions about our society and how sexual harassment is viewed that such a system is required in a professional setting. Maybe such a system is needed in medicine. Much work is clearly still needed on this but the fact we are now openly talking about is a start.

Risk of epilepsy in surgical patients undergoing general or regional anaesthesia. Chang HC, Liao CC, Chang CC et al. Anaesthesia 2017 doi:10.1111/anae.14099

This study looks at the rates of new-onset epilepsy occurring in patients after surgery where they have had either a general or a neuraxial anaesthetic. It is well known that patients who have epilepsy, especially poorly-controlled epilepsy, are at risk, as are patients undergoing brain surgery, open-heart surgery or liver transplantation. But new-onset epilepsy is not something generally that many anaesthetists would consider although both stress and anaesthetic medication have been associated with epilepsy. Previous studies looking at this issue have had many limitations. This nationwide retrospective cohort study of patients in Taiwan sought to evaluate the one-year risk of epilepsy after surgery in patients receiving general or neuraxial anaesthesia.

The Taiwan National Health Insurance Research Database was used to identify patients. Over 200,000 patients were included in each group (general or neuraxial anaesthesia). During the one-year follow-up period the incidence of postoperative epilepsy after general anaesthesia was 0.41 per 1000 and after neuraxial anaesthesia 0.32 per 1000 persons. Compared with patients who had neuraxial anaesthesia, the risk of postoperative epilepsy significantly increased in patients with general anaesthesia when co-existing medical conditions and postoperative complications were included.

This study raises questions about the epileptogenic effects of various anaesthetic agents. But it has limitations. Information about blood biochemistry, lifestyle factors, genetic susceptibility, drug use and the anaesthetic agents used is not available on the database and these could have significant impact on the risk of developing seizures post-operatively. Further clinical studies are needed to be able to draw and firm conclusions.

Doppler-guided goal-directed fluid therapy does not affect intestinal cell damage but increases global gastrointestinal perfusion in colorectal surgery: a randomised controlled trial. Resigner KW, Willigers HM, Jansen J et al. Colorectal disease 2017;19(12):1081-1091 doi:10.1111/codi.13923

Fluid management for colorectal surgery has been much debated recently – should we aim for a restrictive fluid regimen or more liberal fluid treatment? It has been suggested that both restrictive and liberal fluid regimens induce hypo perfusion, the former due to local tissue oedema and the latter due to hypovolaemia. It is also now thought that fluid management in the first hours following surgery may be as important as intra-operative fluid management in improving tissue perfusion and oxygenation. Goal directed fluid therapy (GDFT) has been proposed as a way to reduce complicaations, mortality and length of hospital stay after major colorectal surgery. This study hypothesised that oesophageal doppler guided GDFT as opposed to standard fluid therapy decreased intestinal injury and improved gastrointestinal perfusion during surgery and in the first few hours after surgery.

Patients having elective colorectal cancer surgery with a primary anastomosis were enrolled either to have doppler guided GDFT or standard fluid therapy. All patients had an oesophageal doppler probe inserted and this was kept in situ for a maximum of six hours postoperatively or until the patient could no longer tolerate the probe.

Intestinal damage was determined by measuring intestinal fatty acid binding protein (I-FABP) plasma levels with increasing levels said to correlate with gut-hypoperfusion. Gastric tonometry measuring the intramuscosal carbon dioxide pressure was used to detect gastrointestinal hypoperfusion with the gastric tonometry catheter also left in place for six hours postoperatively.

Interestingly the amount of fluid given did not differ between the intervention and the control groups. The results also showed no difference between the I-FABP levels although the gastric tonometry results indicated better global gastrointestinal fluid perfusion in the intervention group. The clinical outcomes were not statistically analysed but there seems to be relatively little difference between the two groups, although the patients in the intervention group stayed a median of 11 days in hospital as compared to the control groups median of 8 day stay!

Unfortunately this study fails to shed any more light on the best way to manage fluid therapy during major colorectal surgery. Although the authors state that the gastric tonometry results indicated better global gastrointestinal perfusion it is not actually known whether gastric tonometry correlates with colonic perfusion. It is unlikely that these findings will affect current clinical practice anytime soon.

Sugammadex and oral contraceptives: is it time for a revision of the anaesthesia informed consent? Cora DM, Robards CB. Anesthesia & Analgesia 2017 doi:10.1213/ANE.0000000000002677 

This is an interesting letter to the editors raising concerns abut potential issues for women on oral contraceptives who receive sugammadex in the perioperative period. Sugammadex administration can cause certain drugs, including oral contraceptives, to becomes less effective due to lowering of the free plasma concentration. The letter goes on to point out that the drug information that comes with sugammadex states that ‘in vitro binding studies indicate that Bridion may bind to progestogen………the administration of Bridion is considered equivalent to missing dose(s) of oral contraceptives containing oestrogen or progestogen’. The makers of sugammadex recommend that is the patient is taking oral contraceptives and receives a dose of sugammadex then they should be advised to use an additional non-hormonal contraceptive method for the next 7 days.

Sugammadex is not the only drug administered in the perioperative period that could affect oral contraceptives. Many of the routinely used antibiotics can have a similar effect. Currently, there is little emphasis on discussion and counselling patients about these potential drug interactions. The authors suggest that a revision of the anaesthetic consent should contain a general statement to make patients aware that certain medications given during the anaesthetic may interfere with the effectiveness of oral contraceptives. Maybe this is needed but a good starting place would be raising awareness of the issue amongst anaesthetists – in my questioning of a cross-section of anaesthetic colleagues about this issue, no one was aware that sugammadex may interfere with oral contraceptives.

Surgery and discontinuation of angiotensin converting enzyme inhibitors: current perspectives. Bardic N, Povsic-Cevra Z. Current Opinion in Anesthesiology 2017 doi:10.1097/ACO.0000000000000553 

Angiotensin-converting enzyme inhibitor (ACEIs) have been used since the 1970s to treat hypertension with angiotensin II receptors blockers (ARBs) introduced in the 1990s. These medications, collectively known as renin-angiotensin system or RAS antagonists) are thought to work be four different mechanisms:

  1. Cardiovascular protection via reduction of ischaemia
  2. Improvement in cardiac function and short-term survival after myocardial infarction
  3. Antihypertensive effects
  4. Delay in nephropathic progression in diabetic patients

Their use in the perioperative period continues to be a subject of debate. Although the general consensus amongst many anaesthetists is that these drugs should be omitted during the perioperative period in the context intraoperative vasoplegia, previous studies and review articles fail to make any clear recommendations. Multiple studies suggest that patients who take ACEIs or ARBs to treat hypertension are at increased risk of developing severe prolonged hypotension intraoperatively, commonly immediately after induction of anaesthesia.

A large multicentre study published in 2017 (as part of the VISION study) compared patients given ACEIs or ARBs on the day of surgery versus withholding them for 24 hours preoperatively. Their findings suggest that withholding RAS antagonists before major non-cardiac surgery was associated with less risk for complications or death. However, the data from this study had various limitations and it is important to note that withdrawal of ACEIs after surgery is associated with a significant risk of fatal and nonfatal complications postoperatively.

Overall, this article gives a good summary of the recent evidence surrounding RAS antagonists during the perioperative period but still does not provide an answer to the question of whether these drugs should be withheld before surgery or not. It does makes some sensible suggestions as to how to manage these patients:

  • The decision to discontinue RAS antagonists should take into account the original indications for their use, the patient’s clinical status, variability in the patient’s blood pressure and the type of surgery
  • Special attention is needed in surgery with presumed larger blood loss or haemodynamic instability
  • If ACEIs or ARBs are discontinued, they should be restarted as soon as the patient’s condition allows.

Postoperative nausea and vomiting after unrestricted clear fluids before day surgery: a retrospective analysis. McCracken GC, Montgomery J. European Journal of Anaesthesiology 2017 doi:10.1097/EJA.0000000000000760 

Nil by mouth timing remains a contentious issue and a topic that continues to be discussed to great extent in the literature. Current European guidelines encourage the intake of oral fluids until up to two hours before induction of general anaesthesia. The reality is that many patients continue to be starved from the early hours of the morning before surgery and that it is difficult to give patients a true two hour cut-off time for clear fluids.

This study was carried out at Torbay Hospital Day Surgery Unit with a change in the day surgery policy permitting unrestricted clear oral fluids up until the time of transfer to theatre. The aim was to assess the incidence of postoperative nausea and vomiting (PONV) before and after the change to unrestricted pre-operative clear oral fluids.

A total of 11500 patients who received either sedation, general anaesthesia, regional anaesthesia or a combination were included. The results showed a reduction in PONV from 5.2% in patients who could not drink within 2 hours or surgery to 3.8% in patients who had unrestricted clear oral fluids. This suggests that the liberal consumption of clear fluids before the induction of day case anaesthesia reduces PONV.

During the time of the study there were no recorded adverse events of pulmonary aspiration of gastric content requiring patient admission. Since the conclusion of the study a further 10487 patients have undergone surgery on the ‘new’ day surgery pathway which continues to include liberal preoperative clear fluid consumption. During this time there was one episode of aspiration by a patient breathing via a supraglottic airway – the review of the case would suggest that possibly a supraglottic airway was not the most suitable choice for this patient!

This study does seem to present a strong argument that allowing clear oral fluids up until the time of transfer to theatre in day surgery patients is safe, reduces PONV, is not associated with increased episodes of aspiration and gives an improvement in patient satisfaction.

Perioperative fluid therapy….what works?

Fluid therapy in the perioperative setting—a clinical review

Journal of Intensive Care. 2016;4:27. 

Presented by Dr. M. Creed

Background

  • Perioperative hypovolemia and fluid overload have effects on both complications following surgery and on patient survival.
  • Therefore, the administration of intravenous fluids before, during, and after surgery at the right time and in the right amounts is of great importance.
  • This review analyzes the literature concerning perioperative fluid therapy in abdominal surgery and provides evidence-based recommendations for clinical practice.

Design & Setting

  • Clinical Review Article

Results

  • Preoperative oral or intravenous administration of carbohydrate containing fluids has been shown to improve postoperative well-being and muscular strength and to reduce insulin resistance. Hence, the intake of fluid (preferably containing carbohydrates) should be encouraged up to 2 h prior to surgery in order to avoid dehydration.
  • Excessive intravenous fluid administration adds to tissue inflammation and edema formation, thereby compromising tissue healing.
  • During major abdominal surgery a “zero-balance” intraoperative fluid strategy aims at avoiding fluid overload (and comparable to the so-called restrictive approach) as well as goal-directed fluid therapy (GDT). Both proved to significantly reduce postoperative complications when compared to “standard fluid therapy”.
  • Trials comparing “restrictive” or zero-balance and GDT have shown equal results, as long as fluid overload is avoided in the GDT group as well (categorized as “zero-balance GDT”).
  • It is possible that high-risk surgical patients, such as those undergoing acute surgery, may benefit from the continuous monitoring of circulatory status that the GDT provides. Data on this group of patients is not available at present, but trials are ongoing.

Conclusions

  • In elective surgery, the zero-balance approach has shown to reduce postoperative complications and is easily applied for most patients.
  • It is less expensive and simpler than the zero-balance GDT approach and therefore recommended in this review.
  • In outpatient surgery, 1–2 litres of balanced crystalloids reduces postoperative nausea and vomiting and improves well-being.

Strengths

  • Good review of literature, assessing/referencing 71 papers.
  • Data well presented for comparison between trials (Tables 1, 2) and also including data from selected meta-analysis (Fig 1).

Weaknesses

  • An overview of a very broad subject, therefore wide ranging.
  • Review not conducted as a Systematic review and no description of search methodology in arriving at source articles.
  • No meta-analysis of reviewed data other than that taken from other articles.

Potential for impact

  • Provides focus to reflect on perioperative fluid management.
  • May provide opportunity to alter individual practice to reflect current evidence base.

November 2017

Written by Dr C. Williams

Comparison of postoperative outcomes among patients treated by male and female surgeons: a population based matched cohort study. British Medical Journal 2017;359:j4366 doi:10.1136/bmj.j4366

This is a very interesting article published during a time when the argument about males vs females rages on. One only has to do a quick google search to see some of these arguments relating to the medical profession – from female medics have better outcomes to how the high number of female doctors are destroying the NHS.

This population based, retrospective, matched cohort study looked at patients who had surgery between 2007 and 2015. It looked at death rates, readmissions and complications based solely on the sex of the surgeon. The results suggest that patients treated by female surgeons were less likely to die within 30 days but there was no significant difference in readmission or complication rates. This difference in mortality was small and whether it makes any difference to long term survival is unclear. Interestingly no differences were found for patients who were operated on in emergency situations.

This study was done in Canada where, unlike the NHS, patients can freely choose their operating surgeon. The differences seen for elective surgery would suggest confounding factors play a role. The lack of difference in patients having emergency surgery would back this up. So, although an interesting study it would not suggest that one should pick a surgeon based on their sex alone.

Effect of various duration of smoking cessation on postoperative outcomes: A retrospective cohort analysis. Turn A, Koyuncu O, Egan C et al. European Journal of Anaesthesiology 2017 doi: 10.1097/EJA.0000000000000701 

There is now a solid evidence base that smoking is an independent risk factor for perioperative complications. Smokers are 1.4 times more likely to die after surgery than patients who have never smoked. Active smokers also have higher risks of respiratory, cardiovascular and neurological adverse events and are more likely to have problems with infections.

Preoperative smoking cessation would be expected to reduce postoperative smoking and it would be reasonable to expect that longer period of abstinence would correlate with stronger benefits. But the optimal period of preoperative smoking cessation remains controversial. Several randomised trials conclude that 3 to 8 weeks of preoperative cessation reduce wound complications but briefer periods do not seem to reduce respiratory complications. However, a meta-analysis published in 2011 suggested that each additional week of smoking cessation has a significant impact in the reduction in post-operative complications.

Prospective evaluation of the effects of smoking cessation on postoperative outcomes is not easy – a substantial number of patients do not want to stop smoking and even among those that attempt to stop the success rate is thought to be about 50% which makes it difficult to recruit patients in the context of a defined protocol. This paper was a retrospective cohort analysis of adult patients undergoing non-cardiac surgery with the main outcome easier being the relationship between smoking cessation and in-hospital morbidity/mortality.

The summary of the results is that smoking cessation is associated with reduced in-hospital morbidity and mortality – importantly this was shown to be independent of the cessation interval. From a clinical perspective, patients should be encouraged to stop smoking regardless of the time period before surgery.

Incidence of venous thromboembolic events in enhanced recovery after surgery for colon cancer: a retrospective, population-based cohort study. Moms MI, Vendler TA, Haidari JE et al for the Copenhagen cOmplete Mesocolic Excision Study group (COMES). Colorectal disease 2017 doi:10.1111/codi.13910

Abdominal surgery in patients with cancer is associated with an increased risk of venous thromboembolism (VTE). Both the Danish and NICE guidelines recommend prolonged thromboprophylaxis with low-molecular weight heparin for 28 days after executive surgery for colon cancer. The evidence behind these guidelines relies on randomised controlled trials that included both benign and malignant colorectal disorders or colorectal abdominal cancers pooled with other gastrointestinal tract, urinary tract and gynaecological malignancies including palliative surgery. None of these trials included enhanced recovery after surgery (ERAS) programmes.  This study aimed to investigate the risk of symptomatic VTE in patients undergoing elective resection of colon cancer following an ERAS without prolonged VTE prophylaxis.

This was a retrospective analysis of patient who underwent surgery between 2008 and 2013. The median length of stay was 4 days. Of the 1893 patients included, 4 (0.2%) had a non-fatal symptomatic VTE. All 4 of these patients had other postoperative complications prior to the VTE. The rate of VTE found in this study is much lower that the overall 14% risk quoted after major abdominal or pelvic surgery.

It would appear that the risk of symptomatic VTEs is negligible in patients having colon cancer resection following an ERAS programme with an uncomplicated post-operative recovery. It may be that the early mobilisation in an ERAS programme may contribute to the lower risk. The findings of this study suggest that there is a possibility that prolonged VTE prophylaxis may not be cost-effective in these patients.

However, before any changes are made or guidelines rewritten – this is a retrospective study. It does raise questions but further randomised trials are needed to investigate this further.

Randomised feasibility trial of high-intensity training before elective abdominal aortic aneurysm repair. New GA, Batterham K, Colling J et al. British Journal of Surgery 2017 doi:10.1002/bjs.10669

Abdominal aortic aneurysms (AAAs) are usually asymptomatic until they rupture which then carries an overall mortality rate in excess of 80%. Elective surgery, either open or endovascular, is the most effective treatment for preventing AAA-related rupture and death. Open aneurysm repair in particular is associated with neuroendocrine, metabolic and inflammatory changes that lead to an increase in global tissue oxygen uptake of up to 50%. Patients who have a low cardiorespiratory fitness levels are less able to meet these extra demands which can lead to tissue hypoxia and life-threatening complications. A study published in 2010 found that up to half of the patients presenting for intra-abdominal surgery did not have the fitness levels to be deemed at low risk of perioperative complications as quantified by cardiopulmonary exercise testing.

It seems intuitive that improving cardiorespiratory fitness would lead to reduced complications rates after surgery. The clinical effectiveness and cost effectiveness of preoperative exercise testing has not yet been established. It is unclear whether meaningful improvements in cardiorespiratory fitness can be achieved for patients with a large AAA in the limited window available before surgery (usually 4-6 weeks). This study aimed to look at the feasibility and acceptability of high-intensity training (HIT) for preoperative optimisation of patients with a large AAA. Patients were either randomised to usual care or preoperative HIT consisting of three exercise sessions a week for four weeks.

The preoperative HIT seemed to be feasible and acceptable to patients although twenty of the twenty-seven exercise participants had to have their exercise aims adjusted due to triggering safety criteria (such as a systolic blood pressure over 180mmHg). This may have contributed to the fact that measured cardiorespiratory fitness did not change substantially at group level. However, the results seem to point to a beneficial effect of the exercise programme on health status and physical function for up to 12 weeks after hospital discharge.

This feasibility study points to the fact that preoperative exercise and improving cardiorespiratory fitness could be beneficial. Large, multicentre trials that explore clinical and cost effectiveness are needed before recommendations can be safely made about preoperative exercise programmes.

Echocardiography and passive leg raising in the postoperative period: A prospective observational study. El Hadouti Y, Valencia L, Becerra A et al. European Journal of Anaesthesiology 2017;34(11):748-754 doi:10.1097/EJA.0000000000000679 

Perioperative fluid management is a controversial and challenging issue. Both over hydration and conservative fluid therapy can lead to postoperative complications. The difficulty is that many patients have signs that could suggest hypovolaemia (such as oliguria, tachycardia and hypotension) but not all these patients will respond to fluid administration.

Passive leg raising has been demonstrated to simulate preload increase and distinguish fluid responders from non-responders. Studies validating passive leg raising have been carried out most frequently on non-surgical patients. In this study patients in whom low cardiac output was suspected in the immediate postoperative period were included. A baseline echocardiogram was done then repeated 90 seconds after the patients legs had been elevated by 45 degrees. The measurements were repeated after legs had been lowered and finally repeated again after 500mls of fluid administered as a bolus. An increase in cardiac output of greater than 11% after passive leg raising predicted a volume response following fluid with 68% sensitivity and 100% specificity.

This study had a very low sample size and a note is made of difficulty in carrying out the echocardiogram as left lateral decubitus position is best for the echocardiogram but passive leg raising in this position is not really possible. Despite the positive results the potential benefits or clinical uses of using echocardiography and passive leg raising to determine fluid responsiveness remain to be seen.

Acute kidney injury in trauma patients. Harris A, Libert N, Duranteau J. Current Opinion in Critical Care. 2017 doi:10.1097/MCC.0000000000000463 

Multiple organ failure is a later complication of severe trauma that substantially increases morbidity and mortality. Acute kidney injury (AKI) after trauma is associated with an independent association with prolonged hospital stay and mortality. Severe trauma is a time when several renal aggressions occur at the same time making it challenging to establish a strategy to prevent AKI. Factors such as haemorrhage, rhabdomyolysis, traumatic inflammation and renal hits due to emergency surgery or infections may cause acute renal disorders.

The incidence of severe AKI ranges from 9 to 23% and a total of 2 to 8% of trauma patient will require renal replacement therapy. The main risk factors for the development of AKI in trauma patients include haemorrhage, rhabdomyolysis, trauma inflammation, excessive fluid resuscitation and abdominal compartment syndrome.

Trauma care aims at stopping haemorrhage as soon as possible. The earlier this is achieved the better for tissue perfusion. Post traumatic vasoplegic shock can occur and in this situation attention should be paid to arterial pressure to try to optimise renal perfusion. Fluid resuscitation with balanced solute solutions seem to be the most beneficial for trauma patients with regards to AKI although there are no randomised controlled trials looking at this. What this paper makes clear is that AKI is a very real risk for trauma patients and once the initial trauma resuscitation has been carried out special attention should be paid to maintaining renal perfusion. Given the diverse nature of why patients develop AKI after trauma it is difficult to have one protocol to try to reduce the risk.

Sex differences in mortality after abdominal aortic aneurysm repair in the UK. Sidloff D, Saratzis M, Sweeting J et al.  British Journal of Surgery 2017;104(12):1656-1664 doi:10.1002/bjs.10600

Abdominal aortic aneurysm (AAA) screening has been shown to be effective in men both at reducing AAA-related mortality and in cost-effectiveness. Consequently there is now an established AAA screening programme for men over the age of 65 in England and Wales. The benefit of screening for women has not been established. However, one in seven elective AAA repairs are on women and women account for approximately one-third of all deaths from ruptured AAA. Furthermore women have a fourfold higher rupture rate than men at equivalent aortic diameters which suggests there is a strong case for intimating AAA screening in women. Perioperative risk is critical in determining the effectiveness of a screening programme and risk estimates are lacking for women having AAA repairs.

Data from the UK National Vascular Registry was analysed for a 4 year period from 2010 to 2014 with the primary outcome being in-hospital mortality. 13% of the patients included were women. Mortality rates were higher in women for both elective AAA repair (open or endovascular) and emergency repair. The excess mortality rate was found to be largely independent of age, aneurysm diameter and smoking status. It is not clear why this difference in mortality exists although the Canadian Society for Vascular Surgery Aneurysm Study Group identified that women are more likely to be older, have a positive family history of AAA and have significant aortoiliac occlusive disease.

A well designed trial of matched women and men undergoing elective AAA repair would be needed to explain the differences seen. The higher mortality rate in women may have an impact on the benefit offered by any AAA screening programme.

October 2017

Written by Dr C. Williams

Caffeine accelerates recovery from general anesthesia via multiple pathways. Fong R, Khokhar S, Chowdhury A et al. Journal of Neurophysiology 2017;118:1591-1597 doi:10.1152/jn.00393.2017

Currently there is no method to accelerate emergence from general anaesthsia. Patient’s wake when they clear the anaesthetic from their systems. Drugs that had the ability to reverse the coma-like state induced by general anaesthetic agents would likely have considerable utility in clinical settings. In 1975 it was shown that direct intraventricular application of a membrane permeant cAMP analog could accelerate recovery from a variety of anaesthetic and sedative agents.

In 2014 the authors of this study demonstrated that drugs that increase intracellular cAMP dramatically accelerated emergence from anaesthesia. Three intravenous agents that increase cAMP levels were tested – forskolin, theophylline and caffeine – caffeine was shown to accelerate emergence time when anaesthesia was maintained with isoflurane 2%. This study aimed to determine whether caffeine had the same effect at higher anaesthetic concentrations. In this study, rats were anaesthetised for 60 minutes with end-tidal isoflurane levels of 3%. Ten minutes before anaesthesia was terminated the rats were injected with either saline (as a control) or a solution containing caffeine. Recovery time was taken as the time the rat was removed from the anaesthesia chamber, placed on its back on a table to the time it could stand with 4 paws on the table. This study appeared to show that caffeine accelerates emergence from anaesthesia even at high levels of isoflurane. The dose of caffeine was increased by 25mg/kg – starting at 25mg/kg and increasing to 75mg/kg. Caffeine at 75mg/kg produced a 55% reduction in emergence time

Caffeine inhibits phosphodiesterase which prevents the breakdown of cAMP. It also acts as an antagonist at all adenosine receptors. Blockade of the A adenosine receptor mediates caffeine’s arousal effects. Caffeine is already the most psychoactively used drug – in the USA more than 90% of adults use it daily. It is already used clinically either to treat neonatal apnoeas or for certain types of headache and is readily available.

However, this is a small study – no more than 9 rats were studied. There are also questions as to whether this study could be transferred to humans. Also the question as to whether a drug to accelerate emergence is necessary must be raised. It is tempting to speculate about other possible benefits of caffeine. Caffeine is known to have cognitive benefits – hence the reason it is one of the most widely used ‘drugs’. Anaesthetics can impair the cognitive abilities of patients, particularly the elderly, for significant periods of time. If caffeine was shown to accelerate cognitive recovery then it may play a significant role in postoperative recovery. To explore this theory would require extensive research.

Preoperative fluid retention increases blood loss during major open abdominal surgery. Hahn RG, Bahaman H, Nilsson L. Perioperative Medicine 2017;6:12 doi:10.1186/s13741-017-0068-1

Fluid management is an essential component in the management of major abdominal surgery. There is a marked variation in how the kidneys excrete or conserve fluid both in everyday life and preoperatively. Urine analysis can give a measure of the kidney’s state of fluid retention. It is known that a high concentration of urinary waste products is associated with a longer half-life of crystalloid fluid, a greater need for fluid optimisation, more complications after hip fracture surgery and a higher 30-day mortality in acute geriatric care. Little is known about how preoperative fluid retention affects intraoperative fluid balance. The aim of this study was to explore the relationship between preoperative dehydration and fluid requirements during major abdominal surgery with the hypothesis that fluid retention, indicating dehydration would mean more fluid is needed intra-operatively.

Patients undergoing elective open major abdominal surgery had their urine analysed for colour, specific weight, osmolality and creatinine concentration to calculate a fluid retention index. The fluid balance was obtained as the sum of infused fluid (crystalloid, colloid or blood products), minus the blood loss and excreted urine. Fluid retention was found in 37% of patients. It was associated with a significantly higher blood loss, a higher haemorrhage rate and a greater need for intravenous fluids. Despite the larger blood loss, the total fluid balance remained positive after surgery in dehydrated patients.

Preoperative dehydration is associated with higher fluid requirements intra-operatively but also a greater blood loss and a more positive fluid balance. These effects were most apparent in gynaecological and urological surgery. The results from this study would suggest that more fluid should be given to patients found to have concentrated urine preoperatively. More studies are needed to determine if this would improve patient outcome.

Paravertebral block does not reduce cancer recurrence, but is related to higher overall survival in lung cancer surgery: a retrospective cohort study. Lee EK, Ahn HJ, Zo J, Kim K, Jung DM, Park JH. Anaesthesia and Analgesia. 2017 doi:10.1213/ANE.0000000000002342 

Evidence is continuing to emerge about how postoperative analgesic methods have an impact on long-term prognosis after cancer surgery. Opioids trigger immune suppression by impairing innate immunity, altering antigen presentation and predominately favouring pro tumour cytokines. If a patient’s innate immunity is suppressed during the postoperative period there is the potential that remnant malignant cells or micro metastases may grow, establish and spread early after surgery.

Regional anaesthesia can reduce the need for opioids. Using this simple well known fact, it stands to reason that one would expect a lower cancer recurrence and higher survival if regional analgesic techniques were used instead of opioids. This was a large retrospective cohort study aiming to look at precisely this. They hypothesised that thoracic epidural or paravertebral catheters rather than intravenous opioids (via a PCA) as the postoperative analgesic method would be associated with better outcomes in patients undergoing lung cancer surgery.

The notes of 1729 patients undergoing open thoracotomy for primary non-small-cell lung cancer were reviewed. Patients either had a fentanyl PCA, a thoracic epidural with ropivacaine/hydromorphone solution or paravertebral catheter with ropivacaine infusion. Patients had what was then described as a ‘balanced’ anaesthetic  including opioids – either fentanyl boluses or remifentanil infusion. All patients had the same post-operative analgesic protocol for the next 2-3 weeks which was oral analgesics and/or fentanyl patch.

Recurrence rates were similar in all three groups and cancer recurrence was the cause of death in over 80% of the patients in each of the three groups. There was a statistically significant higher overall survival rate in the patients who received paravertebral catheters as the method of post-operative analgesia. Other variables were also related to overall survival including age, male sex, cancer stage, transfusion and duration and extent of surgery.

Unfortunately this study still does not help to answer the questions surrounding the role of anaesthetic techniques on cancer recurrence.

Regional anaesthesia and analgesia in cancer care: is it time to break the bad news? Sekandarzad MW, van Zundert A, Doornebal CW, Hollmann MW. Current opinion in anaesthesiology 2017;30(5):606-612 doi:10.1097/ACO.0000000000000492

The perioperative period is increasingly being recognised as a narrow but crucial window in cancer treatment. As the above paper hypothesises, regional anaesthesia has been proposed to reduce the incidence of cancer recurrence after surgery. There is a separate body of evidence suggesting that perioperative regional anaesthesia may be associated with a survival benefit in cancer patients.

The truth is that existing literature presents conflicting and inconclusive results about the impact of regional anaesthesia on cancer recurrence in patients undergoing surgery. Data is predominantly based on retrospective studies. with as many studies suggesting regional techniques have a positive outcome on cancer recurrence as those that suggest the opposite. The results from meta-analyses and systematic reviews are equally as conflicting. Conflicting results may be due to confounding factors including tumour-specific factors (such as type, grade and lymph invasion) which many studies do not take into account.

It seems unlikely that regional anaesthesia techniques either alone or in combination with modification of other perioperative factors can give clinically meaningful immune-protective effects when powerful chemotherapeutic agents appear to play a small role in cancer survival (contributing to 2% of the 5-year survival in adults). Additionally there is little convincing evidence that opioids promote cancer recurrence or facilitate the development of metastatic disease.

This review article critically refutes the concept that regional anaesthesia as a single modality in the complex oncological setting if cancer surgery can give positive cancer outcomes. The results of ongoing RCTs designed to investigate the link between regional anaesthesia and its ability to reduce cancer recurrence are eagerly awaited although it is unclear as to whether any clear results will be produced. Proving the efficacy of a single intervention (regional anaesthesia) in the multifactorial perioperative oncological setting will be challenging. What is clear is that a reducing postoperative pain and if possible preventing the progression to persistent post surgical pain, even at the expense of no difference in relation to reduced cancer recurrence, is still a goal to aim for.

European guidelines on perioperative venous thromboembolism prophylaxis: Surgery in the elderly. Kozek-Langenecker S, Fenger-Eriksen C, Thienpont E, Barauskas G, for the ESA VTE Guidelines Task Force. European Journal of Anaesthesiology 2017;34:1-7 doi: 10.1097/EJA.0000000000000705

The risk of venous thromboembolism (VTE) is higher in elderly patients particularly those aged over 70 years and elderly patients with co-morbidities. Large population-based epidemiological studies globally show that VTE predominantly occurs in the elderly and rarely occurs prior to late adolescence. But with an increased VTE risk comes an increased risk of bleeding. Therefore it is important to address this issue and ensure that there is appropriate risk stratification, correction of modifiable risks and sustained perioperative thromboprophylaxis.

Limited physiological reserves of older patients make them more vulnerable to postoperative stress and illness including VTE. Factors that have been associated in various studies with deep vein thrombosis and pulmonary emboli in there elderly include: congestive cardiac failure, pulmonary circulation disorders, renal failure, lymphoma, metastatic cancer, obesity, arthritis, post-menopausal oestrogen therapy, anaemia and coagulopathies.

Recommendations for VTE prophylaxis in the elderly are typically extrapolated from non-age specific VTE prophylaxis trials therefore timing and dosing of pharmacoprophylaxis are adopted from the non-aged population.

The general recommendations include:

  • Age over 70 is a risk factor for postoperative VTE
  • In elderly patients identify risk factors and correct if possible
  • Avoid bilateral knee replacements in elderly or frail patients
  • Timing and dosing of pharmacological VTE prophylaxis as in the non-aged population
  • In elderly patients with rena failure, low-dose un-fractionated heparin may be used or weight-adjusted dosing of LMWH
  • Careful prescription of postoperative VTE prophylaxis and early postoperative mobilisation
  • Multi-faceted interventions for VTE prophylaxis in elderly and frail patients including pneumatic compression devices, LMWH (and/or direct oral anti-coagulants after knee or hip replacement)

Risk factors for postoperative ileus after colorectal cancer surgery. Rybakov EG, Shelygin YA, Khomyakov EA, Zarodniuk IV. Colorectal Disease 2017 doi:10.1111/codi.13888

Postoperative ileus is a temporary dysfunction of the gastrointestinal tract in response to surgical intervention. It is a common complication of abdominal surgery and most frequently developed after extensive colorectal operations. It causes significant financial and resource burden on healthcare institutions. The reduction in the incidence of ileus has therefore been placed as one of the top five priorities by the association of coloproctology of Great Britain and Ireland. Treatment is mainly symptomatic as there are no effective pharmacologic agents to treat it, therefore ileus prophylaxis based on the knowledge of potential risk factors is important.

300 patients having elective surgery for colorectal cancer were included. All patients had routine multimodal anaesthesia, a thoracic epidural (with a ropivacaine infusion) and the principles of enhanced recovery were followed: minimal preoperative starvation, no mechanical bowel preparation, no routine use of nasogastric tubes, maintenance of normothermia and minimisation of intraoperative infusions.

Ileus developed in 13% of the patients studied. After multivariate analysis four independent risk factors were identified: a BMI or 26 or over, previous abdominal surgery, the presence of extensive organ adhesions and the administration of opioids in the postoperative period. Importantly due to the fact that every patient in the study had an epidural with a plain ropivacaine infusion only a small proportion (10.7%) required opioids postoperatively. Yet a negative impact of opioids was demonstrated even at this small proportion.

It will never be possible to omit opioids in all patients but actively trying to use techniques that are opioid sparing may be a potential method in which anaesthetists can contribute to reducing the rates of postoperative ileus. This is however a retrospective and relatively small sized study therefore results should be interpreted with some caution.

The impact of fatigue on the non-technical skills performance of critical care air ambulance clinicians. Myers JA, Powell DMC, Adlington S, Sim D, Psirides A, Hathway K, Haney MF. Acts Anaesthesiologica Scandinavia 2017. doi:10.1111/aas.12994

Fatigue and how it affects performance is highly topical at the moment, particularly in anaesthetics following on from the publication of a national survey of the effects of fatigue on trainees in anaesthesia in the UK (Anaesthsia 2017;72:1069-1077) which was reviewed in July’s journal watch.*

This study looked at critical care doctors who are involved in air transfer of patients. The critical care air transport setting is dynamic and challenging and even a small performance decrement has the potential to affect clinical care and patient safety. Fatigue is presumed to negatively influence patient and clinician safety although the precise relationship is not entirely clear. It is also possible that sleep deprived clinicians may not recognise the extent to which their performance is impaired.

Nineteen physicians undertook two different simulated air ambulance missions, once while rested and once when fatigued. Performance was assessed by blinded observers based on expected behaviour in four non-technical skills domains: teamwork, situational awareness, task management and decision making. Participants also rated their own performances. They also completed a psychomotor vigilance task and a cognitive function test.

The physician’s non-technical skills were significantly better across all categories of skills and cognitive tests when rested. Clinicians completed relatively routine air transfer scenarios at levels of fatigue they routinely experience during usual clinical practice (e.g. towards the end of a night shift). Clinician’s also demonstrated limited awareness of their one degraded performance when fatigued. Self-ratings of performance showed no difference between fatigued and non-fatigued performance, in direct contrast to the rating provided by blinded observers.

This study highlights the importance of fatigue and how it can adversely affect performance. There is currently no good policy on recognising and managing the impact of fatigue in the NHS. Hopefully as awareness increases this will be addressed for all healthcare professionals, not only for the impact it has on patient safety but also the long term health impacts of chronic fatigue.

*A national survey of the effects of fatigue on trainees in anaesthesia in the UK. McClelland L, Holland J, Lomas J-P, Redfern N, Plunkett E. Anaesthesia 2017 doi:10.1111/anae.13965

Complications and unplanned admissions in non-operating room procedures. Leslie K, Kave B. Current opinion in Anaesthesiology 2017 doi:10.1097/ACO.0000000000000519 (13)

Increasing numbers of increasingly complex diagnostic and therapeutic procedures are being performed in areas remote from the operating theatre suite. This review aims to look at complications and unplanned admissions in patients requiring anaesthetic care for endoscopy, bronchoscopy and radiology procedures.

For endoscopy large analyses of databases show a low incidence of complications and unplanned admissions. In outpatients the incidence of cardiopulmonary complications was 0.9% – significant predictors included age over 60 years, higher ASA status and inpatient versus outpatient treatment.  Reviews of bronchoscopy seem to show that moderate sedation is tolerated well in these patients. Studies looking at procedures in radiology found that unplanned admissions were more likely to be due to pain, haemorrhage or infection as opposed to a sedation related problem.

Obstructive sleep apnoea has been associated with worse outcomes after procedures in the operating theatre. Studies have shown that OSA in patients having endoscopy or colonoscopy was not associated with any significant increase in cardiovascular or respiratory complications – the authors do make a note that caution should be applied in interpreting this due to poor methodological quality of the studies.

Overall, sedation seems to be associated with a low rate of complications – although some studies suggest more complications during deep propofol-based sedation rather than lighter benzodiazepine sedations. As anaesthetists we would like to think that if we provide the sedation as opposed to it being provided by a non-anaesthetist then it would be safer and have fewer complications. However, studies appear to suggest that sedation provided by anaesthetists is associated with more complications than if given by non-anaesthetists. The reasons for this are not explored but could be related to the fact that anaesthetists may provide sedation for higher risk patients and may provide a deeper level of sedation than non-anaesthetists. Clearly further randomised trials are required to define the optimum sedation drugs, sedation depth and the sedation provider.

Bleeding, trauma and hypothermia…..

Relevance of induced and accidental hypothermia after trauma-haemorrhage – what do we know from experimental models in pigs? Hildebrand et al. Intensive Care Medicine Experimental 2014, 2:16

Presented by : Dr A. Byford-Brooks

Background

  • ‘Lethal triad of trauma’ current model
  • Induced, rather than accidental hypothermia, in animal models has shown potential benefit including:
    • Anti-inflammatory
    • Haemodynamic
    • Reduction of metabolic stress
  • Coagulopathy still a concern
  • Method and technique of cooling could be key

Objectives

  • Benefits/Risks of induced hypothermia
  • Methods of inducing hypothermia
  • Magnitude/Timing/Speed/Duration

Design and Setting

  • Literature review up to July 2013
  • Porcine models of trauma, haemorrhage or combined trauma-haemorrhage
  • Accidental or induced hypothermia
  • Keywords: accidental hypothermia’, ‘spontaneous hypothermia’,‘induced hypothermia’, ‘therapeutic hypothermia’, ‘pigs’, ‘swine’, ‘trauma’, ‘injury’, ‘hemorrhage’, ‘fracture’ and ‘bleeding
  • 36 papers in total

Subjects

  • Porcine models
  • Haemorrhage

1. Controlled à CVC and/or arterial line as %BW

2. +/- Uncontrolled à Surgical insult e.g. Combos of visceral +/- vascular +/- bony trauma

  • Hypothermia

Range:10-35 degrees Celcius (33 deg commonest)

Time: 20mins – 11.5h (2hrs commonest)

Interventions

  • Delay until resuscitation
    • Approximately 0-30s for uncontrolled
    • Approximately 30-40min for controlled
  • Type of resuscitation fluid
    • Crystalloid/colloid (n=19)
    • Blood products (n=3)
    • Combination (n=10)
    • None (n=4)
  • Method of cooling
    • Intraperitoneal packs
    • Cold IVI
    • Cooling blankets
    • Icepacks
    • Roller pump (heparin-free) or CPB (heparin)
  • Method of warming
    • Intraperitoneal lavage
    • Warm IVI
    • Bair hugger
    • Roller pump or CPB
    • No warming

Outcomes

  • Endpoints
    • Mortality
    • Haemostasis
    • Correction of coagulopathy
    • Organ damage e.g. Lactate
    • Use and/or dose of agents being studied e.g. Factor concentrates or haemostatic agents

Conclusions

  • If normothermic – induce hypothermia after primary haemostasis in solid organ damage
  • If accidental hypothermia – correct until haemostats achieved then induce hypothermia (ICU)
  • Rapid cooling better than slow e.g. 2 degrees/min (roller pumps!)
  • Intracorporeal cooling better than extracorporeal (unless also rapid)
  • 34 degrees a good endpoint
  • For aortic trauma – DHCA not more than 60 mins and 10 degrees better than 5 degrees
  • Adequate anaesthesia and relaxation key
  • Rewarming around 0.5 degrees/h
  • No derangements in TEG, coag or Plt between 33-35 degrees
  • Hypothermia reduces plasma levels of inflammatory markers
  • Acidosis in some models due to increased fatty acid vs CHO metabolism and/or slow vs rapid cooling

Strengths

  • Early look at a controversial topic with live subjects
  • Considered multiple models of trauma
  • Compared cooling/rewarming goals and techniques
  • Duration and magnitude of hypothermia

Weaknesses

  • Studies
    • Huge variety in study protocols
    • Circumstances of trauma still artificial and unrealistic
    • Small sample sizes (often <50 total)
    • Type of anaesthesia variable
    • Resuscitation methods (i.e. Crystalloids)
    • Hypothermia often secondary to the study aim
  • Species-specific differences
    • Pigs are hypercoagulopathic compared to humans
    • Acute coagulopathy of trauma (ACOT) has yet to be demonstrated in pigs
    • Despite polytrauma and crystalloid+++, many studies could not induce a coagulopathy
    • Different haemodynamic physiology
  • Long-term effects not investigated
    • Rebleeding
    • Infection
    • Delayed rebound inflammatory response
    • Organ dysfunction on rewarming
    • Posttraumatic apoptosis
  • Subjects with ‘disease states’ not investigated
    • Human population older with comorbidites

Implications

  • Analysis of long-term outcomes not considered
    • Expensive
    • Essentially requires a staffed ICU for the pigs!
  • May lead initially to pragmatic, single-intervention studies on ICU in humans
    • For example in a similar manner to  post-operative cooling in a similar way to out of hospital cardiac arrest or traumatic brain injury
  • Investigation of role of roller pumps in tight thermoregulation and resuscitation

Potential for impact

  • Unlikely to alter current clinical practice with regards to the Lethal Triad
  • However studies suggest mild hypothermia to 34 degrees may not be as deleterious as we think

March 2017

Written by Dr C. Williams

Preparing residents effectively in emergency skills training with a serious game. Simulation in Healthcare 2017;12:9-16 doi:10.1097/SIH.0000000000000194

Technology-enhanced training programmes provide learning opportunities without risk to patients. Full-scale computer-based simulators are expensive to buy and run. With increasing demands on required competencies for doctors there is a need for new and more cost-effective training methods.

This study aimed to look at whether residents preparing for classroom teaching and used a video game and a course manual had better cognitive skills and motivation than those who just the course manual. They found that at the start of a two-week classroom teaching course, residents who had used the video game had better clinical competencies. Yet by the end of the two weeks there was no difference between the groups.

Video games for learning may feature more in the future………Of course this isn’t the first time that video games have been used in teaching – literature has been published on the use of video games to improve surgical skills.

Effects of fluid restriction on measures of circulatory efficacy in adults with septic shock. Acta Anaesthesiologica Scandinavica 2017 doi:10.1111/aas.12862

It is well known that fluid resuscitation is recommended initially in septic shock and continued as long as circulation improves. Hypotension, low urine output and vasopressor requirements are commonly used indicators for giving fluid. Sepsis increases vascular permeability  which can lead to fast redistribution of fluids in the extracellular space and shorten the positive haemodynamic effects of giving fluid. This post-hoc analysis of the multi centre CLASSIC randomised trial compared tow groups of patients with sepsis – either randomised to standard treatment or a restricted resuscitation fluid protocol. They found that fluid restriction had no negative effects on plasma lactate levels, noradrenaline requirements or urine output in the first 24 hours.

This study suggests, but presents no hard evidence, that liberal fluid after the initial fluid resuscitation in the first hour may be harmful. It raises questions regarding fluid resuscitation and highlights the need for further studies.

Normal gastric emptying time of a carbohydrate-rich drink in elderly patients with acute hip fracture: a pilot study. BMC Anesthesiology 2017;17:23 doi:10.1186/S12871-016-0299-6

Fasting guidelines for elective surgery are changing. We now recommend clear fluids until up to 2 hours before surgery. But for patients considered at risk of delayed gastric emptying, which includes trauma patients, the fasting guidelines remain unchanged. Hip fracture patients are often elderly with multiple co-morbidities and many have a pre-existing poor nutritional state. Yet they are often fasted for prolonged periods of time, particularly as trauma lists change and their cases get re-prioritised.

This pilot study looked at whether preoperative gastric emptying was delayed in women with hip fractures awaiting surgery. Nine patient with acute hip fractures were given 400ml of carbohydrate drink along with a paracetamol solution and compared with a group of 10 patients having elective hip replacements and 10 healthy female volunteers. Gastric emptying was assessed by looking at paracetamol absorption. There was very little difference between the three groups.

This is a small pilot study but the results look promising and means that maybe we will no longer have to starve hip fracture patients for hours on end……..

Targeting urine output and 30-day mortality in goal-directed therapy: a systematic-review with meta-analysis and meta-regression. BMC Anesthesiology 2017;17:22 doi:10.1186/S12871-017-0316-4

Urine output is often used as a surrogate measure for organ perfusion and to guide fluid administration. But oliguria is not always due to a suboptimal haemodynamic status and it has been shown that targeting urine output does not prevent acute renal failure. More recently permissive oliguria has been allowed, especially in the immediate post-operative phase.

But there is increasing evidence that a reduced urine output is a risk factor for mortality especially in critically ill patients. Whether this is a casual relation or not has yet to be determined. This study aimed to look at whether including urine output as a target in fluid management protocols reduced 30-day mortality. It looked at 36 randomised controlled trials and 6 observational studies. Analysis of these studies showed that goal-directed therapy decreased 30-day mortality, but when urine output was included as a target this increased 30-day mortality. But once adjustment for confounders was made there was insufficient evidence to associate urine output with mortality. Once again further questions have been raised and more research is needed.

Alpha-range visual and auditory stimulation reduces the perception of pain. European Journal of Pain 2017;21(3):562-572 doi:10.1002/ejp.960

The alpha rhythm (7-14 Hz) is the most studied frequency band in the human brain. They arise from the thalamus and are transmitted via the thalamocortical tracts to the cortex. Alpha rhythms can be influenced by inputs to the thalamus. Neurofeedback studies have found that increasing alpha power can lead to a long-term reduction in chronic pain. But this needs concentration and weeks of training to be effective.

Participants were subjected to a ‘moderately painful acute laser stimulus’ both as a control and following 10 minutes of flashing LED goggle stimulations and 10 minutes of binaural beat stimulation across the alpha range. Both auditory and visual stimulation seemed to reduce pain, although visual stimulation seemed more effective at reducing acute pain. This study provides further evidence that external stimulation can affect pain perceptions. Clinically how relevant this is remains to be seen. Maybe in the future we may be prescribing flashing LED goggles for pain relief??

Maternal deaths in the UK: pre-eclampsia deaths are avoidable. Lancet 2017;389:573-670

Between 2012 and 2014 the Confidential Enquiries into Maternal Deaths and Morbidity found that 241 women died, equating to less than one in 10,000 women. This is the lowest death rate recorded since surveillance been in 1952. In fact, when comparing with age-matched male death rates, a man is more likely to die while his partner is pregnant than she is.

Cardiac disease is the leading cause of indirect deaths while thrombosis and thromboembolism feature as a major issue and are the leading cause of direct death. 59% of indirect maternal deaths related to exacerbation of an underlying condition by being pregnant.

What is clear is that specialist care for women with pre-existing medical problems or mental health problems is paramount. Sadly suicide was the leading cause of maternal death in the first year after pregnancy.

On a positive note deaths due to pre-eclampsia are the least represented category and have substantially reduced since the last report. Pre-eclampsia deaths have been associated with substandard care and should be avoidable. Possibly the introduction of UK evidence-based guidelines which have focused on the systematic use of interventions may have contributed to the reduction? However hypertensive diseases of pregnancy are unlikely to reduce so complacency must be avoided. Pre-eclampsia is only safe for the mother if identified and well-managed.

Resuscitation training for school children worldwide: Kids Save Lives. Anesthesia and Analgesia 2017 doi:10.1213/ANE.0000000000001745

Survival from out of hospital cardiac arrest (OHCA) is low (<6%). A recent study in Europe found that 96.4% of OHCA occurred in a private residence. 54.3% of cases were witnessed by bystanders. 47.7% of cases had bystander initiated CPR. The positive effects of bystander CPR have repeatedly been demonstrated and shown to increase survival by an average factor of 2 to 3. 35.1% of bystanders trained in CPR initiate resuscitation in cases of cardiac arrest versus only 4.8% of those with no CPR training.

To motivate bystanders to perform CPR requires delivering the message that they can do little wrong – the only wrong thing would be to do nothing. There is an argument that CPR training should be incorporated into school curriculum so that the proportion of CPR-trained individuals increased gradually over time. It is mandatory in a few countries and in many more local, regional or national campaigns have been started.

A study published in 2016 showed that the best time to start CPR training was at 12 years of age, and a 2 hour course every year maintained adequate performance. It also showed that children schoolteachers were equally as effective at teaching CPR as healthcare professionals. This had been recognised by the ‘Kids Save Lives’ statement published jointly by the European Patient Safety Foundation, the European Resuscitation Council, the International Lisbon Committee on Resuscitation and the World Federation of Societies of Anaesthesiologists and endorsed by the World Health Organisation. UK schools are not currently obliged to teach first-aid in schools.

There have been various campaigns to make it compulsory but so far without success. In November 2015, a bill to make first aid training compulsory in schools was blocked by MPs talking non-stop until time to discuss and vote on it ran out……………

Can early postoperative oral intake reduce pain & PONV?

 

Early postoperative oral fluid intake in paediatric day case surgery influences the need for opioids and postoperative vomiting: a controlled randomized trial

British Journal of Anaesthesia. 2017;118(3): 407-414

Presented by: Dr T. Sheppard

Background

  • Assessing young children in recovery is difficult and challenging
  • Distress post-operatively is multi-factorial
  • With children too young to communicate effectively, inappropriate treatments can be given

Design & Setting

  • Prospective randomised controlled trial
  • Placebo-controlled
  • Day case paediatric surgery
  • Wide variety of surgery types

Subjects

  • Ages 6m-4yr
  • ASA 1-3
  • GA (Day surgery)

Exclusion criteria

  • Surgery constraining post operative fluid intake
  • Known digestive pathology pre-disposing to POV
  • Enrolment in another study

Intervention

Randomised to 2 groups

  1. Liberal group (offered 10ml/kg apple juice post op)
  • FLACC score ≥4 (Face Legs Activity Crying COnsolability sore)
  • Apple juice offered
  1. Control group (protocolised opioid administration)
  • Opioid given as per unit protocol
  • 2mg/kg nalbuphine
  • Morphine titrated to effect

Also recorded:

  • Number & location of POV (i.e. in PACU/on ward)
  • Ondansetron given on 2nd incidence of POV
  • Prophylactic anti-emetic (dexamethasone/droperidol) if POVOC ≥3

Outcomes

Primary outcome: global incidence of post-operative vomiting during first 3 days after surgery (aim to include delayed POV)

Secondary outcome

  • Total dose opioid analgesics in PACU
  • Length of PACU stay
  • Number of episodes POV in PACU/on ward/on 1st and 3rd post-op days
  • Post-operative adverse events e.g. difficulty swallowing/desaturation

Results

 

Use of opioid post-op

Post operative vomiting PACU stay duration
Liberal group

14.04%

11.4%

53.45 minutes

Control group

35.9%

23.93%

65.05 minutes

  p=0.001 p=0.006

p=0.002

Further split into subgroups

  • Subgroup 1: children randomised as liberal, FLACC score ≥4, accepted apple juice
  • Subgroup 2: children randomised as liberal, FLACC score ≥4, refused drink AND controls
  • Subgroup 1 vs 2: significantly less POV in subgroup 1

Conclusion

If apple-juice offered:

  • Significant reduction in incidence of post-operative vomiting
  • Significant reduction in use of post-op opioids
  • Significant reduction in recovery stay

Strengths

  1. Original study
  2. Randomised controlled trial
  3. Standardised anaesthetic technique
  4. Including pre-med & paracetamol
  5. Prophylactic anti-emetic according to protocol (anaesthetist blinded)
  6. 93-97% use of N2O

Weaknesses

  1. Un-blinded
  2. Study stopped early
  3. Higher incidence of POV in children in this study than previous audit carried out before study completed
  4. Unable to distinguish causes of maladaptive post anaesthesia behaviour
  5. Variations in subgroups 1 & 2
  • Male:female ratio – more males in subgroup 1
  • Less intraoperative fluids given to subgroup 1
  • Fasting times

Implications

  1. This study suggests that early re-instatement of oral fluids significantly reduces incidence of post-operative vomiting
  2. Potential for reduction in opioid use post-op

Potential for Impact

  • Impact of fasting times: 11.3hr pre-op seems excessively long for day case paediatric surgery
  • Could increase list efficiency due to shorter time in recovery
  • Risk assess for use of prophylactic anti-emetic
  • Using standardised criteria for POV in children
  • Should we be prescribing apple juice? Concentrate or pressed? Does it need to be apple juice? Would water be sufficient and have the same effect?

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