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Welsh Anaesthetic Trainees Journal Club

Month

February 2017

Journal Club: 6th February 2017

Changes in stroke volume induced by lung recruitment maneuvr predict fluid responsiveness in mechanically ventilated patients in the operating room

Anesthesiology 2017;126:260-7

Presented by: Dr C Williams

Background

  • Haemodynamic optimisation in the perioperative period can reduce morbidity and mortality
  • Stroke volume (SV) and SV variation/pulse pressure (PP) and PP variation can be used as objective measures of fluid responsiveness.
  • Reliability of SVV and PVV limited in patient receiving low tidal volume ventilation (Vt <8ml/kg predicted body weight)
  • Lung protective ventilation is standard of care for ARDS patients. Also demonstrated to be beneficial in patients undergoing surgery.
  • Lung recruitment manoeuvres (LRMs) are a key component of lung-protective ventilation strategies but as they increase intrathoracic pressure, lead to a decrease in venous return with a subsequent decrease in SV.
  • Authors hypothesised that degree of decrease in SV during LRM could represent a functional test to predict fluid responsiveness.

Design & setting

  • Single centre study
  • No data on the centre – type of hospital etc.
  • Nonconsecutive case series – low quality evidence

Subjects

  • Over 1 year twenty-eight mechanically ventilated patients studied
  • Patients ventilated with low tidal volumes (6-8ml/kg) & PEEP 5
  • All patients needed radial arterial cannula and cardiac output monitoring – unclear if this was standard for surgery or extra for study

Inclusion criteria:

  1. >18 years old
  2. Having neurosurgery

Exclusion criteria extensive:

  1. <18 years old
  2. Intracranial hypertension
  3. Co-morbidities that may affect dynamic waveform indices: arrhythmia, lung disease, EF <50%, possible RV dysfunction, sleep apnoea, COPD, pulmonary hypertension
  4. Extremes of body habitus (BMI <15 or >40)

Intervention

  • Lung recruitment manoeuvre (LRM) by applying continuous positive airway pressure of 30 cmH2O for 30 seconds
  • Volume expansion with 250 ml 0.9% saline over more than 10 minutes
  • Heart rate/MAP/SA/PPV measured before and after both LRM and volume expansion

Outcomes

Unclear exactly what the primary outcomes were. Aims of the study were:

  1. Assess ability of LRM induced decrease in SV to predict fluid responsiveness in mechanically ventilated patients in theatre
  2. Compare the ability of the LRM induced decrease in SV and PPV to predict fluid responsiveness
  3. Assess the relationship between LRM induced SV decrease and SV changes induced by volume expansion

Results

  • Sixteen (out of 28) patients were classified as responders (i.e. SV index increased by >10% after 250ml of fluid)
  • LRM induced a significant decrease (p = 0.001) in MAP and SV in ALL patients
  • Volume expansion caused a significant increase in SV (p = 0.001) in ALL patients
  • The bigger the drop in SV with LRM, the bigger the change in SV after fluid expansion.
  • Drop in SV with LRM was more sensitive and more specific at predicting fluid responsiveness than the change in PPV with LRM
  • Fluid responsive patients had a bigger PPV

Conclusions

  1. A 30% decrease in SV during an LRM could predict the effect of infusing 250ml of fluid
  2. The SV change seen during LRM was a better indicator than PPV to predict fluid responsiveness
  3. The SV change during LRM and the SV change during volume expansion were strongly correlated (i.e. the bigger the SV drop with LRM the bigger the SV increase with fluid)

Strengths

Authors recognise limitations of the study

Weaknesses

Study Design

  • Nonconsecutive case series – definition of nonconsecutive case series is a clinical study that includes some but not all eligible patients identified during the research period. Why were not all eligible patients included? No comment made on this.
  • Low sample size – 28 patients over 1 year period
  • Unclear what primary outcomes were

Patient Group

  • Neurosurgery patients?? Unsure if these are the most appropriate group of patients to carry this study out on! Why would you deliberately chose to carry out a manoeuvre that could alter intracranial pressure and drop blood pressure in this group of patients?
  • Patient characteristics not split into responders vs non-responders – same types of patients in each group?
  • 18 of the 28 patients were ASA III. Large numbers of comorbidities excluded therefore what made them ASA III?
  • Co-morbidities excluded therefore cannot extrapolate results for patient with any kind of arrhythmia, preoperative lung disease or COPD, EF <50%, possible RV dysfunction, sleep apnoea, pulmonary hypertension, extremes of body habitus (BMI <15 or >40) or patients requiring vasopressors/inotropes

Data collection

  • LRM performed in the supine position during steady-state period and before skin incision – results cannot be extrapolated to positions other than supine or after knife-to-skin
  • LRM performed shortly after induction of anaesthesia – haemodynamic effects may have been impacted by degree of vasoplegia due to anaesthetic drugs
  • LRM consisted of applying continuous positive airway pressure of 30 cmH2O for 30 seconds – study authors say results cannot be extrapolated for other LRMs. Is this an adequate LRM? ARDS studies talk about LRM of 2 minutes – would 30 seconds be an adequate time in a clinical situation and how often would it need to be done?
  • Change in SV was estimated using pulse contour analysis technology – accuracy in measuring exact SV disputable. Better for measuring trends over time than SV at a given point

Implications

More objective evidence is needed from a much larger and better designed study to be able to answer this clinical question. Flawed and poorly designed study with many limitations (admitted by the authors). A decrease in SV during LRM may indicate the need for volume expansion but realistically to be clinically effective how often would LRM need to be carried out? Therefore few clinical implications of this study.

Potential for impact

Whist no conclusive evidence is presented in this paper it does highlight that LRMs cause a decrease in SV which can be greater if the patient is hypovolaemic.

This is a good reminder to us all that care should be taken when performing LRMs in patients with cardiac dysfunction or those that are inadequately fluid resuscitated.

January 2017

Written by Dr C. Williams

A systematic review of the analgesic efficacy of cannabinoid medications in the management of acute pain. Acta Anaesthesiologica Scandinavica 2017 doi:10.1111/aas.12851

It is becoming increasingly common to find reports or see patients who are convinced that cannabis or cannabinoid medication help with their acute pain. Recently I have spoken to several elderly patients who like to ‘smoke a joint’ every night because it helps with various aches and pains. This systematic review aimed to assess the analgesic efficacy and adverse effects of cannabinoids when used for acute pain. It looked at 7 studies. 5 studies found cannabinoids worked as well as a placebo, 1 study found them to be superior and 1 found them to be inferior.

Sadly for these patients convinced that cannabis is the answer to their pain, this systematic review concluded that cannabinoids were no better than a placebo either by themselves or combined with opioids and 5 of the studies found that adverse effects were more common than with placebo.

Calling the patient’s own name facilitates recovery from general anaesthesia: a randomised double-blind trial. Anaesthesia 2017;72:197-203

‘The cocktail party effect’ describes the effect where one can tune into one voice even in a noisy room, and also how one can immediately detect words of importance such as hearing one’s name in another conversation.

The authors of this study found that after discontinuing the anaesthetic, calling the patient by their name meant that they opened their eyes quicker and the time to i-gel removal was faster. A BIS of 60 was reached in a shorter time and patients spent less time in the post anaesthetic care unit. There are limitations to the study but either way using the patient’s name is an easy method to aid recovery.

But surely out of respect for the patient should we not be doing this anyway?

Editorial: Real-time physiologic monitoring and physician feedback: Are we ready? Canadian Journal of Anaesthesiology 2017;64:239-241

Individual and group data feedback was given to anaesthetists regarding their management of intraoperative temperature monitoring, firstly the percentage of time the patient was hypothermic and secondly the time taken from the start of the case to the first temperature measurement. Giving feedback didn’t change the amount of time the patient was hypothermic however it did reduce the delay in starting to monitor temperature.

The concept of physician feedback as a QI tool is becoming increasingly popular. The authors reason that the reduction shown in the time taken to start temperature monitoring is evidence that providing feedback may contribute to improved perioperative outcomes.

Or is it possible that giving feedback results in the Hawthorne effect – the knowledge of being measured changes behaviour? Does it matter if the goal is to modify current practice? Individualised and group feedback means we need to accept our imperfections to drive improvement. Hospitals will continue to use QI strategies to improve patient care and reduce costs.

As clinicians we need to accept feedback and undergo a cultural shift from ‘shame and blame’ to high-quality continuous improvement focusing on providing the best care for the patient.

Impact of a perioperative quality improvement programme on postoperative pulmonary complications. Anaesthesia 2017;72:317-327

Postoperative pulmonary complications are

  1. common (incidence of between 2-40%)
  2. associated with adverse outcomes (death/increased length of stay/survival)

Enhanced recovery programmes don’t really address this. A team in Manchester developed an ERAS+ programme aimed at reducing pulmonary complications. It incorporated ICOUGH and surgery school (with videos via youtube). In patients undergoing major surgery admitted to critical care postoperatively, pulmonary complications reduced from 19.3% to 10.5% post implementation of ERAS+. One year after ERAS+ was introduced pulmonary complication rate was 8.7%. Patient surveys showed satisfaction with the surgery school. From the data presented it appeared a relatively low-cost programme to set up. Is the new type of peri-operative pathway involving the patients and their families working with multi-professional healthcare teams where we should be heading? On first glance it seems low-cost, effective and well received by patients………

Surgery School focused on:
Nutrition
Breathing
Activity
Oral health
Psychological support
General health
Family support

 

I incentive spirometry
C cough/deep breathing
O oral care
U understanding patient education
G get out of bed
H head of bed elevation

 

Implantation of an Artificial Larynx after Total Laryngectomy. New England Journal of Medicine 2017;376:97-98 doi:10.1056/NEJMc1611966

Total laryngectomy is a lifesaving operation in patients with advanced laryngeal and hypo laryngeal cancer. But it comes with a substantial reduction in the quality of life.  This is a case report of a patient from France who had an artificial larynx implanted in 2015. The artificial larynx consists of a permanent tracheal prothesis with a removable open-ventilation cap that allows continuous passage of air while protecting the patient’s airway from aspiration. This cap allows the patient to breathe and drink fluids. It also opens transiently with coughing to allow secretion expulsion. Over a 16 month follow-up period the patient was able to breathe and expectorate through the upper airways and maintain oxygen saturations on air. He was able to swallow saliva although occasionally aspirated food.

A very short case report and clearly more work may be needed before this becomes a common place procedure but could this be the future for patients needing total laryngectomy?

Anaesthesia and Developing Brains – Implications of the FDA warning. New England Journal of Medicine 2017 doi:10.1056/NEJMp1700196

For a long time there has been a lot of debate about the neurotoxic effects of anaesthetic agents on the neurodevelopment of young children and foetuses. In 2014 an FDA Science Board meeting found that all anaesthetic agents have ‘immediate neuroanatomical consequences and are associated with long-lasting, if not permanent functional effects’.

Clinically this is a little more difficult to interpret. Healthy children rarely undergo repeated or long procedures under general anaesthetic. Brains of premature or children with congenital heart disease may have already been injured by inflammation or chronic hypoxia before having general anaesthetic. More recent studies have shown that a brief single exposure to general anaesthesia is not associated with poorer neurodevelopment outcomes. More results are expected later this year with the conclusion of the Mayo Anesthesia Safety in Kids (MASK) study.

Yet in December 2016 the FDA issued a ‘Drug Safety Communication’ warning that repeated or prolonged (>3 hours) anaesthesia in children under 3 years old and in women in their third trimester may affect the development of children’s brains. Rarely can procedures be safely delayed if indicated during these periods of life. Is the FDA warning wise?

This will already be a time of high stress for parents and families, and there is a risk that the FDA warning may cause delay in procedures that are needed. Parents, patients and doctors must be careful when considering the risk of delaying procedures due to this warning, especially given it states that ‘additional high quality research is needed’. We must be prepared for this question to be asked given that this was covered in the mainstream media and tabloids at the time………

February 2017

Written by Dr C. Williams

Cardiac arrest, intubation and survival.  Journal of the American Medical Association 2017 doi:10.1001/jama.2016.20165

Since 2010, the importance of tracheal intubation during cardiac arrest in adults has become less important. The optimal approach for airway management during arrest is not clear. This was an observational cohort study of 86,628 adult patients who had an in-patient cardiac arrest between January 2000 to December 2014. Intubation within the first 15 minutes was associated with a lower chance of ROSC, lower survival to hospital discharge with reduced functional outcome. The authors of this study admit that it does not totally eliminate the potential for confounding. However, these findings do not support early tracheal intubation for adult in-hospital cardiac arrest.

 

Intraoperative monitoring of analgesia using nociceptive reflexes correlates with delayed extubation and immediate postoperative pain. European Journal of Anaesthesiology 2017;34:1-9 doi:10.1097/EJA.0000000000000597

Up to 50% of patient have moderate to severe pain immediately after surgery. Does it matter? Not only is it is unpleasant, it can cause hamemodynamic instability, impair wound healing and risk development of chronic pain with reduced mobility. Easy to avoid with long-acting analgesics at the end of surgery……but how to avoid overdosing, prolonged sedation and respiratory depression?

This study looked at the pupillary dilation reflex (PDR) and the nociceptive flexion reflex (NFR) of the biceps femoris. The PDR threshold (PDRT) and the NFR threshold (NFRT) were measured 1 week pre-operatively, then repeated  at the end of surgery. The PDRT and NFRT both correlate with immediate postoperative pain and the time to extubation.

How clinically relevant this is remains questionable. The authors admit the reflexes are of limited use except in clinical studies where clinical variability is reduced. Possibly something for the future?

 

Start2quit:a RCT. Effectiveness of personalised smoking cessation advice. Lancet 2017 doi:10.1016/S0140-6736(16)32379-0

The number of adults smoking in the UK has fallen by more than 50% since 1974, but this has slowed since 2007. The total direct cost to the NHS of smoking-related disease was estimated at £5.2 billion (2005-6). NHS Stop Smoking Services (SSS), established in 2000, effectively help and support smokers to quit with quit rates of about 35%. Despite this fewer than 5% of smokers attend each year – maybe due to the increasing popularity of e-cigarettes?

This study aimed to look at whether showing how smoking related to their individual risk of bad things happening works as motivation. Smokers aged 16 or over were randomly assigned to receive either an individually tailored risk letter and invitation to attend a non-commitment introductory SSS session (intervention group) or a standard generic letter advertising the local SSS group (control group).

Attendance at the SSS group was significantly higher in the intervention group (17.4% vs 9%) although still at the low rate expected for smoking cessation trials. (NB this was just the attendance at the initial SSS meeting and not the quit rate). Possibly a more proactive approach may reduce patient barriers to access treatment and increase uptake of cessation session?

 

Surgical Decision Making: Sharing Decisions……… Journal of the American Medical Association 2017;317(4):357-358 doi:10.1001/jama.2016.18719

Shared decision-making (SDM) is an approach in which clinicians and patients communicate together using the best available evidence when faced with the task of making decisions. It should be a collaboration in which the physician (in this case the surgeon) explains treatment options, elicits values from the patient and importantly guides the conversation towards a decision consistent with the patient’s values and current evidence. Three recent RCTs looked at surgical management in appendicitis, diverticulitis and knee osteoarthritis. The common factor in these studies is that they compared commonly used operations with significantly less aggressive than non-operative alternatives – importantly neither treatment option was superior. However, all studies showed that surgical treatment may be required later on.

Surgical dogma is being challenged – accepted treatment is shifting away from long-established surgical gold-standard treatments. But who and how should the decision be made? The patient-centred framework challenges the ‘one-size fits all’ model. One treatment option is rarely shown to improve outcomes for all important end-points. There are barriers: ‘Surgeons often lack the time or training to talk patients through these complicated trade-offs. They may have concerns about liability for untoward outcomes from unconventional treatments.’ What is clear is that SDM is here to stay and we must find a way to embrace this.

 

Editorial: The never-ending story of the elderly with fractured neck of femur. European Journal of Anaesthesiology 2017;34:115-117

What the literature tell us so far……..

  • In the UK, 30-day mortality is 8.5% – decreasing but still unacceptably high.
  • Hospital stays of <10 days are associated with increased survival 30 days after discharge.
  • 95% of hip-fracture patients have at least one major co-morbidity
  • Unsurprisingly the number of co-morbidities negatively influences the physical and psychological outcomes of patients.
  • Anaesthetic for hip-fracture surgery varies greatly – Regional techniques are associated with a shorter hospital stay but 30-day mortality is no different whether GA or regional anaesthesia is used.
  • Perioperative pain management with a multi-modal approach is vital – implementing fast-track care pathways and early surgery improves 30-day mortality rate.
  • Intraoperative haemodynamic stability seems to improve outcome
  • Anaemia is an independent risk factor for long-term mortality
  • Dedicated geriatric care leads to improved mobility at 4 months compared to standard orthopaedic care.

 

A couple obs related studies…………

Number of pregnancies and atrial fibrillation risk: the Women’s health study. Circulation 2017 doi:10.1161/CIRCULATIONAHA.116.026629

  • This study followed 34,639 women for a median of 20.5 years
  • Having four or more pregnancies means you are 30-50% more likely to develop AF than nulligravida women
  • Possibly thought to be due to repeated exposure to physiological, metabolic or hormonal factors during pregnancy
  • Mainly European women in the study so may not be generalisable to all races or ethnicities

Preterm delivery and maternal cardiovascular disease in young and middle aged adult women. Circulation 2017 doi:10.1161/CIRCULATIONAHA.116.025954

  • Women who deliver their first child before 37 weeks gestation have a 40% greater risk of developing cardiovascular disease later in life.
  • If the baby was delivered before 32 weeks this doubled thee risk of later cardiovascular disease – even when adjusted for pre-eclampsia or gestational diabetes
  • In less than 25% of cases this increased risk was explained by hypertension, hypercholesterolaemia, type 2 diabetes and changes in body mass developing after the first birth.
  • Delivering a preterm infant could be an early warning signal of a high risk for cardiovascular disease

It’s never too early to adopt a heart healthy lifestyle……should we be warning women??

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