Welsh Anaesthetic Trainees Journal Club


April 2017

Myocardial injury after surgery – should we measure troponin more often?

Myocardial injury after Noncardiac Surgery. A large, international, Prospective Cohort Study Establishing Diagnostic Criteria, Characteristics, Predictors and 30-day Outcomes

Anesthesiology 2014; 120:564-78

Presented by Dr S. Tufail


  • Most studies focus on perioperative myocardial INFARCTION
  • Patients sustain myocardial injury in the perioperative period which will not satisfy criteria for myocardial infarction
  • These patients have a poor prognosis
  • Timely & appropriate intervention could potentially improve outcome
  • Proposed definition of myocardial injury after non-cardiac surgery (MINS)
    • Myocardial injury caused by ischaemic (that may or may not result in necrosis), has prognostic relevance and occurs during or within 30 days after non-cardiac surgery.
    • Does not include injury due to non-ischaemic etiology

 Primary Objective:

  • Inform the diagnostic criteria of MINS

Secondary Objectives:

  • Determine characteristics, predictors & 30 day outcomes of MINS

 Design and Setting

  • Used VISION data
  • VISION: The Vascular events In noncardiac Surgery patIents cOhort evaluatioN
    • Large (ongoing) international prospective cohort study
  • Evaluating complications post non cardiac surgery
  • Previous publication showed Troponin in the first 3 days after surgery were independent predictors of 30 day mortality

MINS Study

  • Analyzed VISION data
  • Evaluated troponin elevations until day 30 after surgery
  • Excluded non-ischemic troponin elevations
  • Adjusted for perioperative complications
  • VISION: First 15,000 patients had event rates three times higher than expected. Had enough data for MINS objectives


  • Eligible patients for VISION study:
    • Non cardiac surgery
    • Aged 45 years or older
    • General or regional anaesthesia
    • Elective or urgent/emergency surgery
    • Day or night
    • Weekday/weekend
    • 15,065 patients


  • Patients interviewed, examined & charts reviewed for potential pre-operative predictors of major perioperative complications
  • 4th generation Troponin T (TnT)
    • 6-12 hours post op
    • 1st day, 2nd day & 3rd day
  • TnT 0.04ng/ml or greater, lab threshold for abnormal at time study began
  • If TnT greater than/equal to 0.04ng/ml, assessed patients for ischemic symptoms & ECG
  • If patients developed ischemic symptoms during first 30 days, physicians encouraged to obtain TnT & ECG.


  • Primary Outcome:
    • Mortality at 30 days post op (Cause of death also reported
  • Secondary Outcomes:
    • Patients evaluated throughout hospital stay by research staff
    • Contacted patients 30 days post op-if patient or NOK indicated an event, patient’s notes were reviewed


  • Evaluated all patients with an elevated TnT (1st 30 days)
  • Presence of any ischemic features (? Myocardial infarction)
  • ? Non ischemic reason for raised TnT
  • Check myocardial injury occurred during or after surgery (ie. Not pre-op)
  • Their decisions used in statistical analysis

Statistical Analysis

  • Primary objective: MINS diagnostic criteria
  • Cox proportional hazards model
  • Dependent variable: Death up to 30 days after non-cardiac surgery
  • Independent variables
    • 9 pre-op characteristics (VISION stats)
    • 6 time-dependent perioperative adverse complications
    • Potential MINS diagnostic criteria

Potential MINS diagnostic criteria

  • Peak TnT ≥ 0.04ng/ml with one or more ischemic feature
    • If this- repeat analysis with exploration of impact of each individual ischemic feature on 30 day mortality to decide which to include in MINS diagnostic criteria
  • Peak TnT ≥ 0.04ng/ml without an ischemic feature
    • If this- planned to repeat MINS diagnostic criteria COX proportional hazard model with two more diagnostic criteria
    • TnT 0.02ng/ml & TnT 0.03ng/ml, without knowledge of ischemic features.
    • Reference group (TnT ≤ 0.01ng/ml)
  • After establishing MINS diagnostic criteria, determined the incidence & 95% CI of patients fulfilling these criteria
  • Patients who developed MINS determine incidence of each individual ischemic feature
  • Compared cardiovascular outcomes at 30 days for patients who did and did not suffer MINS (Fischer exact test)

Sample Size

  • Model to determine diagnostic criteria of MINS
  • Evaluated 19 variables
  • Required 228 deaths in the study


  • Model to determine diagnostic criteria of MINS
  • Evaluated 19 variables
  • Required 228 deaths in the study
  • TnT ≥ 0.04ng/ml with one or more ischemic feature
  • TnT ≥ 0.04ng/ml with no ischemic feature
  • TnT ≥ 0.03ng/ml

ALL independently predicted 30 day mortality

  • Diagnostic criteria for MINS (Primary objective):
    • Any peak TnT of ≥ 0.03ng/ml that was judged as resulting from myocardial ischaemia
  • Total of 1200 patients (8%, 95% CI 7.5-8.4) fulfilled the MINS criteria
  • 1% of MINS events occurred within the first two days after surgery
  • 2% of patients suffering MINS did NOT experience ischemic symptoms
  • 9% with MINS did not have an ischemic ECG
  • 8% would have fulfilled definition of myocardial infarction
  • 12 independent predictors of MINS

Prognostic impact of MINS:

  • Increased risk of non-fatal cardiac arrest, heart failure and stroke
  • 30 day mortality rate:
    • 8% in patients who suffered MINS
    • 1% no MINS (OR 10.07; P<0.001)

Predictors of mortality among patients suffering MINS

  • Age ≥75 years
  • ST elevation/new LBBB
  • Anterior ischemic ECG


  • MINS diagnostic criteria established
  • MINS was common (8%)
  • Associated with substantial mortality & CVS complications at 30 days
  • Populations-attributable risk suggests MINS explains 34% of deaths that occur during the first 30 days post op
  • 1 in 10 patients with MINS died within 30 days


  • Large study
  • Prospective
  • Good follow up ( 99.7%)
  • Same Troponin assay


  • Only measured TnT until day 3
  • Can only apply TnT threshold for that one assay
  • Did not assess for ischemic features with TnT 0.03ng/ml
  • May have missed non-ischemic reasons for raised TnT
  • A LOT of stats


  • Should we assess patients for MINS post op?
  • No established effective treatment
  • However, prognosis may be modifiable e.g. aspirin & statins
  • Need for clinical trials to establish strategies to prevent and treat MINS
  • Majority of MINS would go undetected without TnT measurement post op

Potential for Impact

  • ? Ensure modifiable CVS risk factors optimised pre-op
  • ? Increased vigilance in high risk patients
  • Realistically not going to routinely measure TnT post op in all patients
  • Should TnT be added to blood post op if being done anyway?


Midazolam or iPad……which work better?

Children and parental anxiolysis in paediatric ambulatory surgery: a randomized controlled study comparing 0.3mg kg-1 midazolam to tablet computer based interactive distraction.

British Journal of Anaesthesia 2017;118(2):247-253


Presented by Dr R. Morris-Clarke


  • Having an operation is a stressful time for both parents and children
  • Induction of anaesthesia and parent separation creates fear and anxiety
  • May lead to post operative adverse behavioral changes
  • Midazolam and distraction techniques pre-operatively are common place
  • Premedication associated with unwanted side effects
  • Distraction techniques time consuming but cost effective
  • Previous study – children aged 1-11 given a computer tablet for distraction and showed an effective decrease anxiety

Design and Setting

  • Children’s Hospital of the University of Lyon, France
  • Patients admitted to the ambulatory surgical ward – elective
  • 16th May 2013 – 25th March 2014
  • Informed written consent from Parents and assent for children ages 7+
  • Patients randomized via computer programme to:
    • Midazolam 0.3mg/kg PO or PR 20-30 mins prior to anaesthesia
    • IPAD 20 mins prior to anaesthesia
  • Groups kept separate from each other
  • Primary aim – compare the impact of midazolam vs IPAD at mask induction (time 3)
  • Other aims
  • Anxiety measured on arrival to ward (time 1) at separation from parents (time 2) and once back on ward (time 4)
  • Also recorded post operative behavioral changes at home and parent’s overall satisfaction
  • Child anxiety measured by modified Yale pre-anxiety score (mYPAS)
  • 27 items incl. activity, arousal, vocalization, use of parents, emotional state
  • >30 defined anxiety; >40 high anxiety
  • Parent anxiety – State trait anxiety inventory (STAI), higher scores indicate high anxiety
  • Post hospital behavior questionnaire


  1. Children aged 4-10 years
  2. ASA 1-3


  • Pre-operative behavioural disturbances
  • Psychiatric medication
  • Previous history of multiple surgeries (>3)


  • Patients assessed on ward (time 1)
  • Patients assessed with parents on arrival to surgical waiting area (time 2)
  • At Gas induction (time 3)
    • Allowed to carry on playing with IPAD
    • Anaesthesia maintained with sevoflurane
    • GA+/- LA
    • Kept in recovery until no PONV, fully awake, low pain scores
  • Assessed again back on ward (time 4)
  • At home assessments made over the phone at day 1, 7, 14


  • Primary outcome difference between the two group mYPAS scores at gas induction
  • For a power 80% and p<0.05 – 53 patients need in each arm
  • Qualitative and quantitative data was collected and analyzed according to normal distribution fishers exact/x2 test or Wilcoxon nonparametric test as appropriate
  • Statistical analysis was conducted using SAS


  • 118 patients recruited and randomized
  • 60 in IPAD group
  • 58 in Midazolam
    • 3 not included (2 did not receive midazolam and 1 had no mYPAS data)
  • Time 3 (main aim – at gas induction) showed no difference between the two groups
  • 5 vs 41.8
  • Time 2 (assessment of patients in surgical wiaitng area) no difference STAI or mPAS
  • Overall mean mYPAS score less in IPAD group
  • Parents and nurses more satisfied with IPAD
  • Only 40% response rate postoperatively


  • No significant difference to anxiety levels in both groups – either equally good or equally bad. (not previous score of high anxiety was 40 and both groups achieved a mean greater than that.
  • Parents and nurses more satisfied with IPAD – they reported if felt more normal than seeing a semiconscious child
  • Previous trials that had shown a difference between the two did not use a psychiatrist to measure the scores and used different child ages – interpretation bias and someone not accustomed to the questionnaire creating the scores.
  • Low response rate post-operative meant no further conclusions could be drawn

Suggested problems by the authors:

  1. Kids wanted a tablet when they got home
  2. Underpowered
  3. Elective cases only
  4. Low dose of midazolam


  • ‘Fun’ study that has the potential to benefit patients via non-pharmacological methods
  • Use of several common statistical tests
  • Prospective randomized trial


  • No control group i.e. with no intervention
  • iPad 20 minutes before anaesthesia – could the child be bored of it by then?
  • ‘One size fits all’ approach – ipad is a distraction technique but one technique may not suit every child.
  • Why was this published in the BJA and not a French journal. Yet it is being reported in the mainstream media as a positive outcome?
  • How were patients selected? This is not stated. 118 patients of the period of 10 months at a children’s hospital seems a low number.
  • Not blinded – difficult to do.
  • Based on 1 previous positive study
  • Various types of surgery used which may cause different anxiety for different reasons other than anaethesia i.e. cosmetic pinnaplasty
  • Both equally effective or equally ineffective? Who can tell in the end.

Implications/Potential for impact

  • In the elective setting is midazolam appropriate? Post operative drowsiness delaying discharge times.
  • The study implied that the use was normal – everyone?
  • Lead on to further studies regarding distraction versus medication
  • Ultimately will vary anesthetist to anaesthetist and patient to patient


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