Perioperative Risk Assessment Cardiopulmonary Exercise Testing

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Perioperative Risk AssessmentCardiopulmonary
Exercise Testing

• Alastair CJ Windsor MD FRCS

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Enhanced Recovery SurgeryOver Riding Principle
Reduce surgical morbidity Subsequent reduction in
Length of Stay Realise cost savings
NO CHANGE IN DISCHARGE CRITERIA
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(No Transcript)
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Enhanced Recovery SurgeryTwo Key Strategies

• Changing Traditional Surgical Care
• Education, Bowel prep, Fasting, Drains
• Modifying the Surgical Stress Response
• MAS, Afferent neural blockade, Fluid
  management

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Preoperative Education

• Information
• Preoperative plan
• Daily milestones
• Discharge plan
• Medical Assessment
• Alcohol / Smoking
• Social Assessment
• Factors that may delay discharge
• Ward Visit

Enhanced Recovery Nurse Essential
Egbert New Eng J Med 1964 207 824-7 Daltroy
Arthritis Care Res 1998 11 469-78 Wilmore BMJ
2001 322 472-476
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Mechanical Bowel Preparation

• First described in 1959 Considered essential
• Recent changes
• Better surgical technique and peri-operative care
• MBP challenged
• Not considered essential
• Rectal resections remain controversial

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Enhanced Recovery SurgeryTwo Key Strategies

• Changing Traditional Surgical Care
• Education, Bowel prep, Fasting, Drains
• Modifying the Surgical Stress Response
• MAS, Afferent neural blockade, Fluid
  management

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Reducing Surgical Stress
Perioperative Physician
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Morbidity
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Hospital Stay
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Readmission Rates
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Enhanced Surgical RecoveryModerate Gains

• Criticism
• Routine elective patients
• Extend this into Complex tertiary referral care

Preoperative Risk Assessment
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Surgical RiskWhy Should We Attempt To Quantify
Risk ?
Survival After Abdominal Aortic Aneurysm Surgery
Fit for surgery
Unfit for surgery
worse outcome than conservative care
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Surgical RiskWhy do people do some people do
badly?

• Physiological response to surgery
• Oxygen demand increased by as much as 40
• Inappropriate response by Doctor
• Failure to address oxygen delivery needs
• Oxygen delivery Cardiac output x Hb x SaO2 x
  1.34
• Inability to respond by patient
• Oxygen extraction fixed at 35 - 40
• Inability to increased cardiac output
• Inability to increase oxygen delivery (Hb x SaO2
  )

Cardiopulmonary Reserve
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Surgical RiskCan We Measure Cardiopulmonary
Reserve ?

• Age ?
• Exercise ECG ?
• Ejection fraction by Radionuclide
  Ventriculography ?
• Echocardiography ?
• Dobutamine Stress Echocardiography ?
• Dipyridamole-thallium scintigraphy ?

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Survivors were younger did not have congestive
heart failure had better hepatic, renal, and
pulmonary function less extensive involvement if
malignant disease was present and fewer
postoperative complications. If these factors
were removed and only apparently normal
physiologic characteristics considered, there
were no differences in mortality between the
patients over 70 years of age and younger
patients. Age was less of a factor than
physiologic status......
Am J Surgery 1985
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Thoracic
Non - Thoracic
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Objective measure of CP reserve
Cardio-pulmonary Exercise Testing
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The Physiological Principle
VCO2 (ml/min)
VO2 (ml/min)
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Distribution of AT
11 ml/min/kg
Anaerobic Threshold
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Early ischaemiaOnset early and prior to AT
AT 600 ml/min 9.7 ml/min/kg This is moderate
cardiac failure
but note early onset of ST depression
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Physiologically Fit To SurviveThe Marathon Des
Sables
243km/151 miles over 6 days
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Physiologically Fit To SurviveThe Marathon Des
Tables !
243km/151 miles over 6 days
Major surgery !
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How Does That Stack Up with Life....... ?

• VO2 Oxygen utilisation
• 250 ml/min Lying down
• 500 ml/min Sitting Existing
• 750 ml/min Moving around a room
• 75 kg man with AT 10 ml/kg/min 750 ml/min
• Post operative
• Hb falls from 14 to 8
• Overloaded
• Increase 02 demand

Getting him out of bed is Life threatening !!
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CPX Applied to an Elderly Surgical Population
187 pts Major Abdo Surgery
CPX tested AT ml/min/kg
gt11 55pts
lt11 132pts
Overall Mortality 7.8 Non-Surgical 5.9
MORTALITY 0.8
MORTALITY 18
Plt0.001
Older Pl et al. Chest 1993 104(3)701-704.
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CPX Applied to an Elderly Surgical Population
187 pts Major Abdo Surgery
CPX tested AT ml/min/kg
gt11 55pts
lt11 132pts
Pre-operative Ischaemia during testing
MORTALITY 4
MORTALITY 42
Plt0.01
AT lt 11 AND Pre-Op Ischaemia INDEPENDENT RISK
FACTORS
Older Pl et al. Chest 1993 104(3)701-704.
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Cardiopulmonary Exercise Testing Triage and
Outcome Following Major Surgery
Older, P. et al. Chest 1999116355-362
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The Bottom Line

• If the anaerobic threshold was better than 11
  ml/min/kg the chance of survival from major
  surgery was 99.2
• If the AT was less than 11 ml/min/kg coexisting
  with myocardial ischaemia, survival was down to
  only 58.

• Pre-CPEX
• ITU Bed days per 100
• intra-cavity Sx 450

• With CPEX
• ITU bed days per 100
• intra-cavity Sx 220

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The mortality rate is higher amongst patients
who are transferred from surgery to a general
ward and then to ICU, compared to those
transferred directly to ICU (42.5 vs. 19.9)
Improving Surgical Outcomes Group
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UCLH St Thomas Enhanced Recovery Programme

• Busy colorectal units
• Major tertiary element
• Complex IBD
• Recurrent cancer
• EC Fistulae
• Enhanced ERAS
• Pre op CPX
• Periop Doppler Fluid RX
• PACU

• Pre-operative
• Education
• No Bowel Prep
• Carbohydrate loading
• CPX Testing and triage
• Intra-operative
• Minimal access
• No routine NG or drains
• Doppler optimised fluid
• Post-operative
• Epidural
• Mobilisation
• Early feeding
• PACU

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UCLH St Thomas Enhanced Recovery Programme

• 18/10/06 01/02/08
• 294 Consecutive cases (2 Deaths overall rate
  0.7)
• Overall LOS for all elective colorectal
• ERP Median 8 days (2-84) Mean 10.8 days (11)
• Historical
• 2003 Median 14 days (5-175) Mean 19.6 days
  (22.9)
• 2004 Median 14 days (1-72) Mean 18.3 days (15)
• 2005 Median 14 days (2 102) Mean 17.1 days
  (16.6)

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UCLH St Thomas Enhanced Recovery Programme
Distribution of AT (n178)
Number of patients
Anaerobic Threshold ml/kg/min
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UCLH St Thomas CPX and Anaerobic Threshold
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A Randomised Controlled Trial of the Utility of
Cardiopulmonary Exercise (CPX) Testing for
Preoperative Risk Stratification to
Guide Perioperative Care and Thereby Reduce
Postoperative Morbidity
Centers UCLH and Whittington
Control - Standard Perioperative Pathway
Clinician guided care for choosing
postoperative care environment Intervention -
Perioperative care pathway guided by CPX
Results Perioperative care pathway guided by CPX
results AT gt 11ml/min/kg no myocardial
ischaemia or Ve/VO2 lt35 - Level 1 Ward Care
AT gt 11ml/min/kg with myocardial ischaemia or
Ve/VO2 gt35 - Level 2 HDU AT lt 11ml/min/kg -
Level 3 ITU AT lt8mls/min/kg - Level 3 ITU /
consider cancellation or alternative procedure
Study ID Numbers 07/0114, NHNN REC NO
07/H0716/55, NIHR PB-PG-0906-11426
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Summary

• Surgical outcome is a complex multi-factorial
  issue
• Enhanced Surgical Recovery is gaining popularity
• Reducing morbidity and hence LOS
• Predominantly for routine elective surgery
• Risk assessment may allow extension of ERAS to
  more complex surgery
• CPX appears to be reliable and reproducible
  surgical risk assessment tool