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Welsh Anaesthetic Trainees Journal Club

Month

May 2018

Journal Club: 30th May 2018

Abnormal routine pre-operative test results and their impact on anaesthetic management: An observational study.

Indian Journal of Anaesthetics 2018;62:23-8. DOI: 10.4103/ija.IJA_223_17

Presented by: Dr Benjamin O’Donovan, ST4 Anaesthetics

Background

In spite of guidelines from the ASA and NICE, and a lack of evidence for ‘routine’ pre-operative investigations they are still frequently carried out. These investigations may identify previously unknown abnormalities resulting in changes to pre-operative management. This study aimed to assess the prevalence of abnormal test results and their impact on the peri-operative management of patients undergoing elective surgery.

Design & Setting

An observational prospective study, in a tertiary care teaching hospital.

Subjects

414 consecutive patients aged 12 years or older, male or female, attending preassessment clinic for non-cardiac surgery were used.

Exclusions

  • Pregnant patients
  • Bedridden or immobile patients (unable to assess body weight)
  • Patients under the age of 12 years old

Intervention

Data collected:

  • Demographics
  • ASA grade
  • Grade of surgery (NICE classification)
  • All investigations and results prior to being declared fit for surgery were noted including:
    • Haemoglobin less than 10g/dL
    • Platelets less than 100
    • Elevated blood sugar
    • Abnormal TFTs
  • Newly diagnosed comorbidities from investigations were noted.

NB: New diagnoses of hypertension were not counted

Outcomes

  • An abnormal result was said to be ‘impactful’ if it resulting in referral, delay, further investigations, retesting or changes in anaesthetic management plan.
  • This was said to be a significant impact if the resulting change was in the perioperative anaesthetic management.
  • An abnormal but potentially expected result leading to a change in management was not counted.

Results

  • 345 (11.6%) of results were abnormal
    • 56 abnormalities had an impact
    • 20 had a significant impact.

NNI for significant impact was 21 and detecting new abnormality was 28. Average

Conclusions

  • Over half of patients in the study have abnormal test results
  • 8% of tests have an impact on patients
  • 67% of tests have significant impact.

Strengths

  • National Journal
  • Prospective study
  • Appropriate study power calculation
  • Largely reasonable exclusion criteria
  • Positive subject to investigate in terms of rationalising healthcare expenditure.

Weaknesses

  • Observational study
  • Single centre
  • Unclear if protocol for requesting pre-operative investigations
  • 12 seems an odd age for cut off of lower limit
  • Not affecting peri-operative management doesn’t necessarily mean no significant patient impact.

Implications

We over investigate our patients by the parameters of impact/significant impact set out in this study.

Potential for impact

Given that this study indicates that patients are over investigated at pre-operative assessment there would be the potential for significant cost-saving by reducing the number of investigations requested.

 

 

Journal Club: 23rd May 2018

Perioperative aspirin therapy in non-cardiac surgery: A systematic review and meta-analysis of randomized controlled trials

International Journal of Cardiology 2018;258:59–67 

doi: 10.1016/j.ijcard.2017.12.088 0167-5273

 Presented by: Dr L Jones

Background

  • Cardiovascular and bleeding events are amongst the leading complications during surgery
  • Aspirin is the cornerstone of secondary prevention of cardiovascular disease
  • As an irreversible cyclooxygenase-I inhibitor, aspirin poses a bleeding risk
  • For non-cardiac surgery aspirin’s benefits and bleeding risks remain unclear

Design & Setting

  • A systematic review and meta-analysis of randomised controlled trials
  • Aspirin v no aspirin in non-cardiac surgery
  • All cause mortality, cardiovascular mortality, arterial ischaemic events, venous thromboembolic events and bleeding events separately evaluated

Subjects

  • 7 relevant prospective randomised controlled trials
  • 28302 patients
  • Intermediate risk cardiovascular-risk surgery

Intervention

  • Different for every trial but a variation on aspirin at various doses v no aspirin

 Outcomes

  • All cause mortality (All trials)
  • Cardiovascular mortality (All trials)
  • Perioperative MI (All trials)
  • Major Bleeding (All trials)
  • Cerebrovascular events (6 trials)
  • Peripheral arterial events (3 trials)
  • Venous thromboembolic events (4 trials)

 Results

  • All-cause mortality (3.7% vs. 3.8%; odds ratio (OR) 0.97, CI 0.86–1.10) and cardiovascular mortality (2.0% vs. 2.1%, OR 0.92; CI 0.78–1.09) were not different in aspirin vs. no aspirin groups.
  • Arterial ischemic events showed no differences, including myocardial infarction (2.5% (aspirin) vs. 2.5% (no aspirin)), cerebrovascular events (0.6% (aspirin) vs. 0.6% (no aspirin)) and peripheral arterial events (0.2% (aspirin) vs. 0.3% (no aspirin)).
  • Aspirin significantly reduced the risk for venous thromboembolic events (VTE; 1.5% (aspirin) vs. 2.0% (no aspirin); OR 0.74, CI 0.59–0.94, p = 0.02).
  • Perioperative major bleeding was significantly more frequent in aspirin groups (4.4% vs. 3.7%; OR 1.18, CI 1.05 to 1.33, p = 0.007).

 Conclusions

  • Aspirin showed no difference in terms of mortality v no aspirin for intermediate risk non cardiac surgery
  • Aspirin significantly reduced the risk for VTE but also had a significantly higher major bleeding risk

 Strengths

  • Meta-analysis of RCTs
  • High sample size
  • Easy to measure primary outcomes

 Weaknesses

  • Not all trials included secondary outcome measures eg. VTE risk
  • Variance in doses of aspirin per study
  • Some studies (PEP, POISE-II and STRATEGEM) used other anticoagulants as well as aspirin

 Implications

  • Aspirin showed no mortality benefit therefore the initiation/ continuation of aspirin in the perioperative period for intermediate risk surgery is not recommended.
  • Aspirin showed a 25% risk reduction in VTE for orthopaedic surgery and therefore should be considered as prophylaxis alongside other anticoagulants

 Potential for impact

  • Conclusive evidence for stopping aspirin in the preoperative period for intermediate risk surgery. This helps in decision making in the pre assessment clinic.
  • Consideration for adding aspirin to VTE prophylaxis protocols

Journal Club: 16th May 2018

Incidence and risk factors of anaesthetic-related perioperative cardiac arrest. European Journal of Anaesthesiology 2017;34:1–7 doi:10.1097/EJA.0000000000000685

 Presented by: Dr R Dean-Paccagnella

Background

  • Many studies have analysed perioperative mortality in speciality sub-groups, but few have looked at unselected patient populations. Many studies have excluded patients undergoing cardiac surgery.
  • Previous papers have studied perioperative mortality but have not independently reviewed the incidence and risk factors of cardiac arrest.
  • This study aims to measure the incidence of perioperative cardiac arrest in an unselected anaesthetic population and retrospectively identify significant risk factors.

Design & Setting

  • Retrospective cohort study of non-ITU patients undergoing anaesthesia between January 2007 and December 2012 at a single tertiary hospital in Cologne, Germany.

Subjects

  • 169,000 adult and paediatric patients underwent anaesthetic procedures within the time period.
  • Study population (n 318) was identified by the screening of critical incident report forms, performed by the authors.
  • Cases were categorised into 1. “anaesthesia related” (directly caused by an anaesthetic procedure), 2. “anaesthesia contributory” (caused by both surgical and anaesthetic events) or 3. “anaesthesia contributory” (possibly caused by factors under the control of the anaesthetist).

Intervention

  • Undifferentiated anaesthetic procedures were analysed retrospectively.

Outcomes

  • Incidence of pulselessness requiring chest compressions within 24hours after anaesthetic procedure.

Results

  • Incidence of perioperative cardiac arrest was 5.8/10,000 anaesthetic cases (95% CI 4.7-7.0).
  • Significantly increased risk of perioperative cardiac arrest was associated with ASA grade or 3 or more, revised cardiac risk index of 3 or more, NYHA or 3 or more, out of hours procedures, emergency surgery and pre-existing cardiomyopathy.
  • Multi-variate logistic regression identified 3 predictors of perioperative cardiac arrest. ASA grade of ≥3 (OR 2.59, p=0.007, 95% CI 1.29 to 5.19), emergency surgery (OR 4.00, p=0.001, 95% CI 2.15 to 7.54) and pre-existing cardiomyopathy (OR 17.48, p= <0.001, 95% CI 6.18 to 51.51).
  • Age over 75 years or less than 3 years, Gender, BMI ≥30 kg m3 , and patients with known difficult airways were not identified to be at significantly altered risk of perioperative cardiac arrest.

Conclusions

  • Patients with an ASA physical status grade of ≥3, undergoing emergency surgery or with pre-existing cardiomyopathy appear to be at an increased risk of perioperative cardiac arrest in this single centre European university hospital population.
  • Incidence of paediatric cardiac arrest directly caused by anaesthesia was high (5 of 12 cardiac arrests directly related to anaesthetic procedure).

Strengths

  • Clinically relevant question addressing entire anaesthetic population.
  • Findings are in-line with previous papers addressing ASA grade and risk of anaesthesia related cardiac arrest.

Weaknesses

  • Risk factors were identified retrospectively by reviewers. NYHA classification appears to have been categorised retrospectively by investigators.
  • Strength of relationship between anaesthetic procedure and cardiac arrest categorised by authors (although independently).
  • Single centre European study which may not provide generalisable results.
  • Main outcome measure is an infrequent event, and as such small variation in number of events will greatly influence the frequency reported.

Implications

  • ASA grading, urgency of surgery and pre-operative identification of cardiomyopathy may help identify high risk cases.
  • Further studies of peri-operative cardiac arrest would be improved by establishing a consensus for the definition of anaesthesia-related and anaesthesia-contributory cardiac arrests.
  • Incidence of anaesthesia-related cardiac arrest appears to remain relatively high in the paediatric population.

Potential for impact

  • If felt to be generalisable, ASA grade ≥3, emergency surgery and cardiomyopathy may indicate patients at significantly increased risk of perioperative cardiac arrest, although this remains an infrequent event.

 

 

Journal Club: 9th May 2018

The Clinical Impact of Cardiology Consultation Prior to Major Vascular Surgery

Annals of Surgery 2018, 267 (1): 189-195. doi: 10.1097/SLA.0000000000002014.

 Presented by: Dr S O’Beirn

Background

  • Cardiovascular complications are the leading cause of morbidity and mortality in adult patients undergoing major vascular surgery.
  • Despite the perceived benefit of preoperative Cardiology consultation in high risk patients the evidence for this and the guidance for which patients it would be of greatest benefit remain unclear.
  • This study aims to analyse the impact of pre-operative Cardiology consultation rates on the incidence of post-operative Myocardial Infarction (MI) at the individual and Hospital level.

 Design & Setting

  • Retrospective analysis of a large prospective multicentre observational registry based in 29 hospitals across the state of Michigan from Jan ’12 to Dec ’14.

Subjects

  • 5191 cases undergoing Open Peripheral Arterial Bypass (n=3037), Open Abdominal Aortic Aneurysm Repair (n=332) or Endovascular Aneurysm Repair (n=1822).
  • Cases excluded Emergency surgery, Carotid Endarterectomy or Stenting, Age <18 or BMI <10 or >80.

Intervention

  • Preoperative Cardiology consult defined as a documented Cardiology clinic or In hospital consultation within 6 months prior to the procedure.

Outcomes

  • Primary Outcome of Perioperative Myocardial Infarction (PoMI) defined as a rise in cardiac biomarkers combined with either Ischaemic symptoms, new Ischaemic ECG changes, pathological Q waves or Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality.
  • Secondary Outcomes included the development of a dysrhythmia, congestive heart failure or cardiac arrest within the initial hospitalisation following the operation.

Results

  • Patients undergoing pre-operative Cardiology consultations had significantly higher rates of Perioperative MI (2.7% vs 1.47%, p=0.002).
  • No significant variation in mortality (1.57% vs 1.10%, p=0.147).
  • Huge variation in rates of Cardiology consultation across centres (6.9%-87.5%, median 53.3%).
  • Lower rate of Perioperative MI at the quartile of centres with the highest rate of consultations OR 0.52 (0.27-0.98, 95% CI, p=0.045).

Conclusions

  • Higher rate of PoMI amongst patients undergoing pre-operative Cardiology consultation, though this can likely be explained by these patients being at higher risk due to operative and patient factors.
  • No significant variation in rates of PoMI within quartiles when cases grouped according to Revised Cardiac Risk Index.
  • Reduction of PoMI seen in hospitals with higher rates of preoperative Cardiology consultation. The specific mechanism of this is unclear. Suggestion of “Hospital culture” as a factor.

Strengths

  • Large sample size at the patient level.
  • Reporting of negative results.
  • Clinically relevant question.

Weaknesses

  • Retrospective analysis of previously published data.
  • Acknowledged limited data on the outcome of preoperative consultations.
  • Significant cofounders unaccounted for (Intraoperative anaesthetic and fluid management, technical skill of the surgeon, critical care management).
  • Lack of cost analysis.
  • Potential for lack of generalisability given all centres within 1 state.
  • Significant inter-quartile variability within rates of PoMI among centres with low rates of preoperative consultation.
  • Multiple implications drawn from lower rates of PoMI amongst high preoperative consultation centres despite only just attaining significance at a 95% CI (p=0.045).

Implications

  • Based on this study, centres with higher rates of preoperative medical consultation have lower rates of perioperative complications, specifically perioperative MI amongst patients undergoing elective major Vascular surgery.
  • However, this is not demonstrated by this data on a patient level and the implication is that variation in hospital culture is a key confounder.

Potential for impact

  • Limited potential for impact as failure to demonstrate improvements in perioperative outcomes on the patient level and lack of suggestion as to which patient groups may benefit from undergoing preoperative consultation.

 

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