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Welsh Anaesthetic Trainees Journal Club

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February 2018

Journal Club: 28th February 2018

Evaluation of reliability of MYZONE MZ-3 Heart Rate Monitor: A study for the Future of Telephysiotherapy for Preoperative Prehabilitation in Cancer Patients.

TELEMEDICINE and e-HEALTH 2017;23(4):1-5 doi:10.1089/tmj.2016.0138

Presented by: Dr C Francis

Background

Pre-operative optimisation programs seek to implement a series of interventions to improve and enhance recovery after major surgery. An important aspect of this is the use of exercise programs. The Authors of this paper suggest a major barrier to successful completion of these programs could be inaccessibility of in-hospital supervised exercise programs. There is an increasing abundance of wearable technology, however the accuracy and reliability of commercially available Heart Rate monitors is variable.

Design & Setting

Small, prospective, pilot experiment at single centre in Australia. Small sample (n=7) of young, healthy volunteers without significant medical history and in normal sinus rhythm recruited. Asked to perform increasing intensity effort on exercise bike wearing the MYZONE MZ-3 Heart rate monitor and a clinical 3 lead ECG system. Paired HR measurements to be taken and compared statistically using a Bland Altman plot

Subjects

Seven young physically active, healthy individuals in normal sinus rhythm (mean age 29.7 years; 5 female, 2 male)

Intervention

Asked to complete an exercise on static bike of increasing intensity whilst wearing both clinical 3 lead ECG and MYZONE MZ-3 HR monitor.

Outcomes

1,983 data points collected. Of which 55 data points unpaired as loss of contact with MYZONE MZ-3 HR Monitor. Only paired data sets included. Significantly 5 of the 7 participants had their collected data received out of sync, reported as being due to a failure to manually synchronise time on both MYZONE MZ-3 HR and ECG monitors pre test. Authors included this data after retrospective correction of data by aligning out of sync data, moving the sample to the left by 20 seconds. The authors feel this adjustment of data unlikely to cause any clinically significant effects on results.

Results

Using a Bland-Altman plot able to demonstrate a bias of 0.4bpm, and adjusted 95% limits of agreement (95% LOA) to be -4.5 to +5.3 bpm. And a percentage error [95%LOA/mean HR] of 3.6%

Conclusions

MYZONE MZ-3 has an acceptable level of reliability for use in healthy volunteers performing exercise across a wide range of HR. Further studies using a similar methodology are required to validate the use in patients presenting for cancer surgery.

Strengths

  • Prospective study
  • Appropriate use of statistical analysis to assess reliability and precision of HR monitor.

Weaknesses

  • This study had a very small sample size, of healthy, young volunteers. Therefore, this cannot be extrapolated to those awaiting cancer surgery.
  • None of the participants were noted to have any features which may have produced inaccuracy such as arrythmias, obesity, tremor, pacemakers.
  • A static bike was used and so there was minimal movement artifact.
  • 55 data sets were not paired due to the loss of contact with HR monitor and are not included in reliability figures.
  • Perhaps most significantly there is retrospective alteration of the data collected from 5 out of the 7 participants. Whilst the authors claim this is unlikely to have caused significant effects to the results I fail to see how an experiment with aims of assessing precision and accuracy of a piece of equipment can be deemed safe when 5/7 of data sources have been altered retrospectively.
  •  In addition, there was no structured exercise protocol used and no examination of the cost benefit of the intervention.

Implications

  • Limited at present.
  • Could be deemed a starting point for a project requiring significant further examination.

Potential for impact

Increasing numbers of wearable technologies are available and being used in the community. There is much competition between devices and price points are changing dramatically as with most tech products. The use of these products could be of great use in prehabilitation of pre-operative patients. There is much scope for further investigation and cost benefit analysis of this and similar products.

Journal Club: 21st February 2018

Intraoperative Infusion of Dexmedetomidine for Prevention of Postoperative Delirium and Cognitive Dysfunction in Elderly Patients Undergoing Major Elective Noncardiac Surgery: A Randomized Clinical Trial.

JAMA Surgery. Published online June 2017. doi:10.1001/jamasurg.2017.1505

Presented by: Dr B Morris

Background

This study aims to tackle the issue of high rates of post operative delirium (POD) and post operative cognitive dysfunction (POCD) in elderly patients. There is thought to be a high incidence of POD (10-60%) and this is also thought to contribute to POCD, a more permanent alteration of mental state. Both these conditions are associated with disadvantageous features such as increased perioperative morbidity, increased length of stay and ultimately decreased life expectancy and quality of life, so it is a significant problem. The authors aimed to evaluate specifically the perioperative use of an infusion of Dexmedetomidate as this has been shown to improve delirium and cognitive dysfunction in ICU patients.

Design & Setting

A double-blind, randomized, parallel group placebo-controlled trial in 10 centres across the USA over 6 years (2008 – 2014).

Subjects

Of 404 patients who were initially randomized, 390 made it through to be included in the results of the trial. These were patients selected by the following criteria: Age over 68 (adjusted from 70 in the interest of gaining more numbers), undergoing major (planned 2 day admission) elective non-cardiac surgery under GA. There was a long list of exclusory criteria, including surgical, anaesthetic and patient factors such as intracranial/emergency surgery, planned post operative intubation, life limiting conditions, preexisting cognitive conditions and ASA IV/V.

Intervention

An infusion of 0.5mcg.kg-1.hr-1 of Dexmedetomidine commenced in the anaesthetic room and continued until 2 hours into recovery, vs placebo of saline.

Outcomes

Primary: Presence of delirium whilst hospitalised or until day 5 post operatively.

Secondary: Post operative cognitive decline up to 6 months post operatively.

Results

The trial was stopped early due to futility and failure to find any difference between the two groups.

Primary outcome:

23 patients from the Dexmedetomidine group (12.2%) and 23 patients from the control group (11.4%) developed post operative delirium (risk ratio, 1.06; 95% CI, 0.79-1.41; P = .77). Interestingly they did isolate some other factors that made POD more likely – namely increased length of surgery, baseline mild cognitive impairment, lower number of educational years and type of surgery, general surgery being the least likely to be associated with POD.

Secondary outcome:

There was found to be no statistically significant difference between the two groups in POCD at either 3 or 6 months.

Unintended adverse events:

Similarly distributed between the two groups, with more bradycardia with the Dexmedetomidine group and slightly more infections, although the overall number of infections was low.

Conclusions

This study contrasted with other work on administration of dexmedetomidine in the postoperative setting of 1 or more days in cardiac and non-cardiac surgical patients, which has shown an improvement in POD.

This study did show some correlation between other factors such as educational level and baseline mild cognitive impairment and POD.

Encouragingly, there was little evidence of POCD in either group, perhaps indicating that although Dexmedetomidine is not beneficial, these patients in general are not at high risk for significant POCD anyway.

Strengths and Weaknesses

The exclusion of so many patients did allow for a more robust scientific analysis of Dexmedetomidine and its effects, as the two groups being compared were homogeneous, however this did limit the study’s usefulness in real terms as it may be in many of these excluded patients interests to have POD decreased, more so than the ‘fitter’ population studied.

Whilst absolute presence of delirium was measured, a weakness of the study is that the number of episodes, severity and consequences i.e. length of stay, etc. were not.

Implications

Basically, based on this study, we should not endeavour to provide intraoperative Dexmedetomidine infusions to elderly patients undergoing major non cardiac surgery in an attempt to ameliorate POD/POCD.

Potential for impact

This is a useful piece of research in the full context of Dexmedetomidine and POD, but needs to be taken into consideration with all of the other work done in the surrounding areas of other types of surgeries, other populations and prolonged administration post operatively.

Further research should be directed at the higher risk groups that were excluded from this study, and more far-reaching measures such as improvement in patient outcomes (both clinically objective and subjective), length of stay, financial efiiciency etc. It is also still perfectly reasonable to consider providing post operative Dexmeditomidine infusions to high risk patients in HDU/ICU environments in the absence of deleterious factors.

Journal Club: 6th February 2018

Effect of Individualized vs Standard Blood Pressure Management Strategies on Postoperative Organ Dysfunction Among High-Risk Patients Undergoing Major Surgery A Randomized Clinical Trial. 

The Journal of the American Medical Association. 2017;318(14):1346–1357 doi:10.1001/jama.2017.14172

Presented by: Dr J Lloyd

Background

Perioperative hypotension is known to be related to post operative organ dysfunction, in particular the heart, lungs, and kidneys.

Patients at high-risk of post operative organ dysfunction are also at an increased risk of mortality.

Hypertension is an increasingly common comorbidity, especially in the elderly population, and it alters the autoregulatory capacity of their brain and kidneys leaving them more vulnerable to ischaemia during an episode of hypotension than organs of normotensive patients. It is thus hypothesised that maintaining a higher systolic blood pressure during surgery, in high risk patients with hypertension, will reduce the risk of post operative organ dysfunction.

Guidelines for critical care have suggested altering haemodynamic targets to premorbid levels in hypertensive patients, but there is no good evidence for the same advice in the operating theatre.

This study aims to determine whether adjusted intraoperative haemodynamic targets in hypertensive patients can reduce the incidence of post operative organ dysfunction, and mortality

Design & Setting

A multi-centre, stratified, parallel control group randomised clinical trial conducted across 9 hospitals in France

Subjects

Patients over 50, with an ASA classification of II or greater, undergoing surgery with an expected duration of over 2 hours, and with an acute kidney injury risk index of III or higher (see figure below)

JC 6th Feb figure

Figure from: KheterpalS,TremperKK,HeungM,etal. Development and validation of an acute kidney injury risk index for patients undergoing general surgery: results from a national data set. Anesthesiology. 2009;110(3):505-515.

Intervention

The patients reference blood pressure was measured preoperatively, and then the two arms of the study were protocolled as follows:

  • Experimental group – a 2.5mg in 250ml noradrenaline infusion was administered peripherally to maintain a systolic blood pressure within 10% of the reference pressure.
  • Control group – 6mg boluses of ephedrine (up to a maximum of 60mg before the use of rescue noradrenaline was permitted) were used to treat any drops in systolic BP below 80mmHg or any more than 40% below the reference pressure.

Other aspects of care were standardised such as:

  • Measurement of BP through a radial arterial line
  • Anaesthetic induction with the use of propofol 2-3 mg/kg, sufentanil 0.2 μg/kg and cis-atracurium 0.15 mg/kg. Inhaled anesthetics used for maintenance of general anesthesia, to a target bispectral index between 40 and 60, in addition to intravenous perfusion of sufentanil at 0.1 to 0.2 μg/kg per hour.
  • Mechanical ventilation with the use of a tidal volume between 8 and 10 ml/kg predicted body weight, with a positive end-expiratory pressure between 5 and 10 cmH2O, an inspired oxygen fraction (FIO2) to maintain oxygen saturation ≥95% and the respiratory rate adjusted to maintain end-tidal carbon dioxide concentration between 30-35 mmHg.
  • Blood transfusion to maintain hemoglobin level at greater than 10 g/dl.
  • Core temperature maintained at 37°C.

Outcomes

Primary outcome is a composite measure that includes both meeting the SIRS criteria, as well as demonstrating major organ dysfunction from either the cardiovascular, respiratory, renal, neurological, or coagulation systems within 7 days of the operation.

Secondary outcomes included

  • Intraoperative blood pressure variability, blood loss volume, transfusion requirement, fluid requirements, and rescue vasopressor therapy, as well as incidence of either hypotension, hypertension, or bradycardia
  • Post operative urine output, RIFLE score, requirement for renal replacement, SOFA score, duration of ICU and hospital stay, as well as a wide range of specified postoperative complications within 30 days

Results

The primary outcome event incidence was 38.1% in the treatment group and 51.7% in the control group, this gave an adjusted relative risk of 0.73 with 95% CI of 0.56 to 0.94; P = .02

Of the secondary outcomes:

  • Renal dysfunction occurred in 32.7% in the treatment group Vs 49% in the control group (adjusted relative risk 0.70 with 95% CI of 0.53 to 0.92; P = .01)
  • Altered neurological function occurred in 5.4% of the treatment group Vs 15.9% of the control group (adjusted relative risk, 0.34; 95% CI, 0.16 to 0.75; P = .007)

Conclusions

Individualised targeting of systolic blood pressure in high risk patients reduces the risk of both post operative renal and neurological dysfunction

Strengths

  • Adequately powered, well designed randomised control study, with clear inter group standardisation of care
  • A clinically relevant question

Weaknesses

  • The two regimes use two different vasopressors to attain their haemodynamic goals, so it is possible that some of the difference in outcomes could be from a pharmacological rather than haemodynamic difference.
  • Reference values for preoperative blood pressure values may not always be available in clinical practice for example with emergency surgery.
  • Necessary lack of intervention blinding for the anaesthetists delivering care
  • HES boluses to achieve maximal cardiac index is no longer standard practice, although it was the same protocol in both groups
  • Large numbers of patients were excluded based on their risk score for post operative renal impairment, which means we cannot extrapolate the results to answer the question about how this majority of patients should be treated

Implications

  • In cases of expected prolonged surgery, where patients are known to be at risk of post operative renal dysfunction, maintaining systolic pressures of within 10% of their baseline will decrease the risk of post operative renal and neurological dysfunction.
  • It also demonstrates the safety of peripheral dilute noradrenaline, as no adverse outcomes were reported

Potential for impact

Widespread application of the conclusions has the potential to reduce morbidity in a high risk patient group

February 2018

Written by Dr. C. Williams

Comparison of 4 cardiac risk calculators in predicting postoperative cardiac complications after non cardiac operations. Cohn S, Ros NF. The American Journal of Cardiology 2017 doi:10.1016/j.amjcard.2017.09.031

Identifying patients who are at high-risk of perioperative complications is something that we are still trying to refine. There are many risk calculators available to try to identify all kinds of risk – ranging from cardiovascular risk, risk of acute kidney injury, risk of post-operative cognitive dysfunction, risk of mortality and so on. Trying to work out which is the best risk calculator to use can seem like trying to negotiate your way through a minefield.

We know that cardiovascular complications after non cardiac surgery are an important cause of postoperative morbidity and mortality. One can use different risk calculators and get different estimates of the patients risk but which is the most reliable risk predictor? This is a question this paper tries to answer by looking at 4 different cardiac risk calculators.

Trying to identify high risk patients is not a new phenomenon – the first cardiac risk index was published by Goldman et al. in 1977. This was followed in 1999 by Lee at al publishing the revised cardiac risk index (RCRI). In 2013 Davies et al. improved prediction using a 5 factor reconstructed RCRI (R-RCRI). The 2014 ACC/AHA guidelines on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery recommended using the RCRI or two newer tools created from the National Surgical Quality Improvement Program (NSQIP) database – namely the myocardial infarction or cardiac arrest (MICA) calculator or the American College of Surgeons surgical risk calculator (ACS-SRC).

Essentially this paper found that all 4 risk calculators performed well at defining low and elevated risk groups but tended to slightly underestimate cardiac events. There are two salient points made:

  1. The definitions for outcomes and timeframes used to develop the risk calculators are different therefore a valid direct comparison of outcomes is not possible
  2. If the risk calculators are used in a manner different from the way derived they do not perform as well

Ultimately risk calculators give an estimate of risk – it is not a black/white answer as to whether that patient will develop that particular complication. What they are useful for is to facilitate shared decision making discussions with patients and enable them to make an informed decision regarding their treatment choice.

Postoperative ERAS interventions have the greatest impact on optimal recovery: Experience with implementation of EAS across multiple hospitals. Aarts M, Rotstein O, Pearsall E metal on behalf of the iERAS group. Annals of Surgery 2018 doi:10.1097/SLA.0000000000002632 

ERAS (Enhanced recovery after surgery) pathways use evidence-based practices to minimise perioperative stress and promote early recovery. These multimodal care pathways incorporate multiple interventions within the preoperative, intraoperative and postoperative course of the patient’s perioperative journey. Multiple papers have been published which demonstrate that ERAS benefits patients when compared to standard care and show a decreased rate of complications, accelerated recovery and earlier discharge from hospital.

But while ERAS has been shown to be effective at improving outcomes, it can be difficult to implement not least because it requires a sustained collaborative effort from members of a multidisciplinary team. This paper aims to determine which component of ERAS has the largest impact on recovery for patients undergoing colorectal surgery and also to look at the relative benefits of ERAS in laparoscopic versus open surgery.

Of the 2876 patients studied only 20.1% had care that was compliant with all phases of the pathway. The poorest compliance was for the postoperative interventions yet these were the interventions most strongly associated with an optimal recovery. Compliance with ERAS was associated with improved outcomes regardless of whether surgery was open or laparoscopic. However, the impact of ERAS compliance was significantly greater in patients having open surgery.

In addition to the ERAS components two other potentially modifiable factors were found to significantly impact on patient outcomes namely operative technique and preoperative haemoglobin levels.

Maybe it is time to go back and reassess how ERAS is implemented. My view as an anaesthetist is that it seems that more emphasis is placed on the preoperative and intraoperative parts of the pathway – the question is whether this is because that is what happens or because those are the parts of the pathway that anaesthetists are more involved with? There is plenty of emerging evidence that postoperative care is as important as other parts of the pathway and if the results of this study are valid then it would seem that postoperative interventions make the most difference to patient outcomes. Once again this paper adds to the increasing body of evidence that as anaesthetists it may have come to the time that we need to step up to the mark and pay more attention to postoperative care. After all, why take so much care making sure our patients are as pre-optimised as possible and given the best intraoperative care if we do not follow this through to the postoperative phase?

Preoperative geriatric assessment and tailored interventions in frail older patients with colorectal cancer: a randomised controlled trial. Ommundsen N, Wyller TB, Nesbakken A et al. Colorectal Disease 2018 doi:10.111/codi.13785

The role of comprehensive geriatric assessment for older patients undergoing surgery is much discussed in the literature at the moment. Geriatric assessment and input has already been shown to make a difference and improve functional status in hip fracture patients. This paper aimed to looks at whether a preoperative geriatric assessment can identify older patients at risk of developing postoperative complications after surgery for colorectal cancer. Patients over the age of 65 years scheduled for elective colorectal cancer surgery and fulfilling criteria for frailty were randomised to either a preoperative geriatric assessment and a tailored intervention (based on the assessment) or usual care.

The findings of this paper were that a geriatric assessment and tailored intervention made no difference to the rate of complications or to the secondary endpoints of median length of stay, discharge to own home, need for readmittance or reoperation within 30 days or 30 day and 3 month mortality.

In my opinion there are significant limitations to the data in this study – despite running for a long period of time (2011 – 2014) only 122 patients were recruited and consequently the study is probably underpowered (acknowledged by the authors). Also, the optimal time from intervention to surgery was hypothesised to be 3 weeks – which seems a short time period for an intervention to make a significant difference to outcome. Furthermore the authors go on to detail that the actual time for pre optimisation was a median of 6 days. Additional evidence is needed to be able to draw conclusions as to the effectiveness of geriatric assessment on patient outcomes particularly given that geriatric input has been shown to be efficient in other surgical settings.

Does goal-directed haemodynamic and fluid therapy improve peri-operative outcomes? A systematic review and meta-analysis. Chong MA, Wang Y, Berbenetz NM, McConchie I. European Journal of Anaesthesiology 2018;35:1-15 doi:10.1097/EJA.0000000000000778 

There is much debate about the effectiveness of perioperative goal-directed haemodynamic and fluid therapy. The seminal study by Shoemaker et al published in 1988 demonstrated that patients receiving preoperative haemodynamic optimisation titrated to goals of end organ blood flow had improved outcomes. Since then there have been multiple randomised controlled trials looking at this. In my personal experience many anaesthetists have quite polarised views on the efficacy of goal directed therapy.

The authors carried out a systematic review and meta analysis of 95 randomised controlled trials where goal directed therapy was studied defined as fluid and/or vasopressor therapy titrated to haemodynamic goals. The findings of this comprehensive review demonstrate that goal directed therapy modestly improves mortality in non-trauma and non pregnant adult surgical patients. The authors suggest that based on the articles included for analysis, the numbers suggest tat for every 1000 patients treated with goal directed therapy, 18 deaths would be prevented.

However, the quality of evidence was low to very low with much clinical heterogeneity among the goal-directed therapy devices and protocols. This is likely to be an area of continuing interest for perioperative research and further well designed and adequately powered trials are needed. Hopefully the OPTIMISE-II and FLO-ELA trials may answer some of the questions surrounding goal directed therapy.

Clinical guideline and recommendations on pre-operative exercise training in patients awaiting major non-cardiac surgery. New GA, Ayyash R, Danjoux GR. Anaesthesia 2018 doi:10.1111/anae.14177

Pre-operative exercise has been much debated over the past few years. There have been several systematic reviews on the effects of pre-operative exercise with sufficient clinical trial data to support pre-operative exercise training as being safe and efficacious. But how exactly can one translate the evidence from clinical trials into clinical practice. This paper aims to provide practical and evidence-based guidelines on how to deliver pre-operative exercise training to patients awaiting major, non cardiac surgery.

Chronic physical inactivity accelerates age-associated declines in maximal aerobic capacity and functional fitness which consequently places individuals at increased risk of complications when undergoing major or complex surgery.

There are ten key recommendations which cover patient selection for exercise training in surgical patients, integration of exercise training into multi-nodal prehabilitation programmes and advice on exercise prescription factors and follow-up. This guideline also touches on the fact that successful implementation of rehabilitations programmes may prove challenging. A range of institutionalised cultural and attitudinal barriers exist that could affect pre-operative initiatives to a varying degree. System-related barriers include lack of educational opportunities highlighting the benefits of exercise, insufficient infrastructure and concerns about the feasibility of delivery and cost effectiveness of potential programmes. Several barriers to implementation are highlighted – the main ones being resistance to change from patients and staff and lack of funding or support from management.

Although the authors acknowledge that further research is needed to identify the optimal exercise prescription, this is a much needed clinical guidelines. Hopefully it will result in perioperative teams being able to incorporate pre-operative exercise training for patients into their routine practice.

Association between handover of anesthesia care and adverse postoperative outcomes among patients undergoing major surgery. Jones PM, Cherry RA, Allen BN et al. The Journal of the American Medical Association 2018;319(2):143-153 doi:10.1001/jama.2017.20040

This article looked at over 313000 patients to look at whether handing over of care from one anaesthetist to another during surgery is associated with a worse outcome. Given the shift work that many anaesthetists (particularly trainees) now work, handing over of care during surgery cannot always be avoided. Handovers may be temporary (initial clinician hands over care to another clinician for a break and then returns) or complete (care is completely handed over to another clinician). Handover is a potentially vulnerable time for the patient because all information required must be transferred between clinicians in a busy environment with many distractions. If crucial details are missed the patient may be at risk of an adverse event. The alternative theory is that a rested clinician taking over care from a fatigued clinician may improve the quality of care and reduce adverse events.

Complete intraoperative handover of care compared with no handover of care was associated with a higher risk of all-cause death, hospital readmission and major postoperative complications over 30 days (44% versus 29%). Intraoperative handovers were also associated with an increase in intensive care admissions and a longer hospital stay.

This is a topic which raises many questions. The authors note that in Canada the number of complete handovers of care is increasing each year. Fatigue and the effects that it has on performance at work is also much debated at the moment.* Knowing that fatigue exacerbates many human limitations, some departments have implemented policies of restricted duty hours for medical staff. It is likely that these policies have an impact on the number of handovers of care.

Given the increase in adverse events observed in this study, the public health implications are concerning. The most prudent approach would be to minimise unnecessary anaesthetic handovers. However the factor of fatigue cannot be ignored. At some point fatigue will have a measurable and detrimental effect on clinicians and handovers in this case would be reasonable. But the question of how to determine when the risk of a fatigued clinician exceeds the potential risk of a complete handover is not one that can currently be answered.

(*July 2017A 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)

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