Pre Operative Assessment Of The High Risk Surgical Patient

1
Pre Operative Assessment Of The High Risk
Surgical Patient

• Lui G Forni NG Lavies
• Department of Critical Care
• Worthing Southlands Hospitals

2
Introduction

• Identifying the High Risk Patient
• Risk Scoring
• CVS Risk Assessment
• How we have addressed the problem
• Future Developments

3
Introduction

• Over 20,000 patients a year die following surgery
• Most die within 30 days of surgery on general
  wards

4
Introduction

• Improved Surgical Outcomes Group recommended
  (2005)
• improved pre-op assessment
• improved intra-operative care
• improved use of post operative resources
• This followed Association of Anaesthetists
  guidelines
• Hopefully should lead to improved outcomes

5
How Do We Identify The High Risk Surgical Patient?

• Surgical Factors
• Patient Factors

6
Surgical Factors

• Different operations have different mortality
  rates
• 0.5 for elective THR
• 13 for elective oesophagogastrectomy
• Emergency operations have higher mortality
• 10.7 for elective surgery patients
• 36.8 for emergency surgery patients

7
Urgency and Operative Mortality

• Mella BJS 98
• Colorectal surgery audit
• Operations carried out urgently have a higher
  mortality rate for same ASA

8
Surgical Factors

• Intermediate Risk (lt5)
• Intraperitoneal surgery
• Intrathoracic surgery
• Head and neck surgery
• Major Orthopedic surgery
• Prostate surgery

• High Risk (gt5)
• Major emergency procedures eg acute abdomen,
  major trauma
• Aortic/major vascular surgery
• Prolonged surgery with large fluid shifts/blood
  loss
• Peripheral vascular surgery

• Low Risk (lt1)
• Endoscopic procedures
• Superficial procedures
• Cataract surgery
• Breast surgery

9
Patient Factors

• Age
• Existing Co-morbidity
• Exercise Tolerance
• Medication

10
Patient Factors Age

• Higher number of concurrent disease processes
• Decline of physiological reserve with ageing
  (cardiovascular/pulmonary/renal/musculoskeletal)
• ? Increased morbidity mortality with age

11
CEPOD Deaths by Age 1998/9
12
Effect of Age on Mortality Post Op (NCEPOD 2001)
of Total Deaths/Operations
Age in Years
13
Patient Factors

• Age
• Existing Co-morbidity

14
Co-existing Medical Problems and Perioperative
Death (NCEPOD 2002)
age of patients
15
Patient Factors Cardiovascular Disease

• Approximately 75 of patients who suffer
  perioperative death have cardiovascular disease

16
Patient Factors Cardiovascular Disease

• Risk factors for cardiovascular death within 30
  days of operationHowell SJ et al BJA 19988014
• Previous MI (odds ratio 4.04)
• Angina (odds ratio 3.55)
• Hypertension (odds ratio 2.53)
• Renal Failure (odds ratio 4.23)
• Cardiac Failure (odds ratio 2.8)

17
Pre-operative Risk Scoring

• Various Scoring Systems Published
• ASA (1963)
• Goldman Cardiac Index (1977)
• Detsky Cardiac Index (1986)
• Possum (Copeland 1991)
• Lee Revised Cardiac Index (1999)

18
Pre-operative Risk Scoring

• ASA
• Fit, healthy patient
• Mild systemic disease
• Severe systemic disease-limiting activity but not
  incapacitating
• Incapacitating systemic disease-a constant threat
  to life
• Moribund-not expected to survive

19
ASA and Perioperative Mortality (NCEPOD 2002)
age of deaths
ASA
20
Lee Cardiac Risk Index(Lee et al Circulation
1999 1001043)

• 6 Point Score one for each of the following
• High risk surgical procedure
• History of IHD
• History of CCF
• History of Cerebrovasular disease
• Insulin-dependent diabetes mellitus
• Chronic renal failure (creatinine gt177)

21
Lee Cardiac Risk IndexValidated in 1422
non-cardiac surgical patients

• Risk of major cardiac complications
• (MI, pulmonary oedema, VF or primary cardiac
  arrest, complete heart block)
• 0 point 0.4
• 1 point 0.9
• 2 points 7
• 3 or more points 11

22
Lee Cardiac Risk Index

• Applied to 1351 major vascular surgical patients
  (Boersma et al 2001)
• 1 point 1.3 risk (of MI or death)
• 2 points 3.1 risk
• 3 or more points 9.1 risk

23
Cardiovascular Risk Assessment

• How can we assess cardiac risk?
• Static Testing
• Electrocardiography
• Transthoracic Echocardiography
• Transoesophageal Echocardiography
• Cardiac catheterisation
• Dynamic Testing

24
Improving Risk stratification

• Dynamic Testing
• Exercise Tolerance
• Exercise ECG testing
• Dobutamine stress echo
• Dipyridimole stress echo
• Dipyridimole thallium scintigraphy
• Cardiopulmonary exercise testing

25
Pre-operative Functional Assessment

• 1 MET 3.5 ml O2 / kg / min (Oxygen consumption
  by 40 yo 70 kg man at rest)
• 1 MET eating and dressing
• 3 MET light housework, walking 100m, golfing
  with a cart, slow ball-room dancing
• 4 MET climbing 2 flights of stairs
• 6 MET short run
• gt10 MET able to participate in strenuous sport

26
Exercise Tolerance and RiskReilly DF et al Arch
Intern Med 19991592185

• 600 patients undergoing major non-cardiac surgery
• If unable to walk 4 blocks and climb 2 flights of
  stairs poor exercise tolerance ie lt 4 METs
• Patients with poor exercise tolerance had twice
  the incidence of perioperative complications
  (cardiovascular and neurological) 20 vs 10
  plt0.001

27
Cardiopulmonary Exercise Testing

• Myocardial ischaemia in absence of heart failure
  has little effect on outcome (Older et al 1993)
• CPET is an objective test to determine
  pre-operative fitness
• Correlates well with post operative survival
• Can identify patients with an increased risk
  profile where surgery may be inappropriate

28
Cardiopulmonary Exercise Testing

• Examines the ability of the CVS to deliver oxygen
  to tissues under stress
• If a patient is unable to elevate oxygen delivery
  to the required levels they are more likely to
  have a poor outcome

29
Cardiopulmonary Exercise Testing

• The patient is asked to exercise at a known work
  rate on some form of ergometer while a number of
  variables are measured
• (1)  ECG
• (2)  Blood pressure
• (3)  Expired air flow
• (4)  O2 uptake from the air
• (5)  CO2 output from the body
• (6)  Arterial blood gases.

30
Parameters Measured

• VO2 - volume of oxygen consumed
• ml/min (absolute)
• ml/kg/min (relative)
• METS - metabolic equivalents
• 1 MET 3.5 ml/kg/min
• VCO2 - volume of carbon dioxide produced
• ml/min

31
Parameters Measured

• During exercise, when rise in VCO2 becomes
  disproportionate to rise in VO2
• Indicates the level of exercise where body has
  reached maximal aerobic capacity
• Termed the Anaerobic Threshold

32
Anaerobic Threshold by Age
33
Parameters Measured
34
Cardiopulmonary Exercise Testing
35
Cardiopulmonary Exercise Testing

• Cardiopulmonary Exercise Testing
• Older P. et al Chest 1993 104 701

• 187 major abdominal surgical patients over 60
• Defined the Anaerobic threshold by exercise
  testing

Anaerobic threshold lt11 ml/min/kg
Anaerobic threshold gt11 ml/min/kg
N132
N55
Mortality rate 0.8
Mortality rate 18
36
Cardiopulmonary Exercise Testing

• 4 METS 14 ml/kg/min O2 consumption BUT
• 80 of elective major abdominal cases have an AT
  of lt 14 ml/kg/min
• Only those with AT lt 11 ml/kg/min (32) are high
  risk
• Clinical differentiation between these groups not
  possible
• CPX testing required to identify the high risk
  group

37
Does It Work?
548 Patients having major abdominal surgery
AT gt 11 ml/min/kg Myocardial Ischaemia
AT gt 11 ml/min/kg No Myocardial ischaemia
AT lt 11 ml/min/kg aortic / oesophageal surgery
ICU (28)
HDU (21)
Ward (51)
7 died (4.6)
2 died (1.7)
0 died (0)
38
Now we have identified the high-risk patient
What do we do next?
39
How We Addressed The Problem

• Both clinicians were aware of the need to offer
  selected pre-operative assessment
• Joint anaesthetic and medical clinic to assess
  high risk patients started in 2003
• The Surgical Pre-assessment Anaesthetic and
  Medical clinic
• SPAM clinic

40
The SPAM Clinic

• Consultant Lead
• Allows Medical Anaesthetic Review
• Assess patient
• Discuss pre/post operative care
• ?Assess risk

41
The SPAM Clinic

• Had several perceived potential benefits
• Both clinicians actively involved in ITU and
  manage the patients post operatively
• Outpatient assessment enables relative ease in
  ordering appropriate investigations and follow up
• Allows objective assessment of the patient by 2
  experienced clinicians and should prevent
  cancellations

42
The SPAM Clinic

• Routine pre-assessment is still performed in
  our trust
• Where problems arise the SPAM clinic allows a
  point of easy referral
• Referral occurs from
• surgical colleagues where they feel additional
  assessment is required
• anaesthetic colleagues
• All major surgery requiring ITU post operatively
  is referred routinely

43
The SPAM Clinic

• Does it work?
• The results shown are from the initial 125
  patients seen in the SPAM clinic
• Follow up data was collected from the patient
  notes or GP after 6 months

44
Referral Pattern
SD
Age
Male
Total
Speciality
8.9
77.6
93
23
Urology
8.1
80.0
52
15
Orthopaedics
2.1
29.5
0
3
OG
12.4
70.6
45
59
Surgery
13.0
69.0
72
18
Upper GI
45
Results

• 90 deemed fit for surgery
• 33 deemed unfit
• 2 refused surgery (?SPAM Effect)
• No significant differences between the groups
  other than age

46
Results
lt.05
Age
NS
Lee Cardiac Index Score
NS
Number of Co-Morbidities
NS
Number of Medications
47
Outcomes From Clinic/Surgery
Mortality ()
6 Month Mortality
Number
9.7
9
92
Fit Patients
36.4
12
33
Unfit Patients
48
Causes of Death
Unfit
Fit
4
5
Disease Progression
4
0
Myocardial Infarct
2
2
CVA
1
0
GI Bleed
1
1
Other
0
1
Refused Surgery
49
Results

• Significant reduction in mortality is observed in
  the group deemed fit for surgery
• ? may reflect the overall differences in case mix
  
• Is this the whole story?

50
Results

• No! Not the whole story..
• 9 patients of the 92 deemed fit for surgery died
  within 6 months of assessment
• But 6 died before operation
• 1 refused surgery
• 2 died of CVAs
• 3 died of disease progression and deemed
  inoperable
• Only 3 died within 6 months of surgery who had
  surgery

51
Results

• Therefore of those deemed fit for surgery 3 died
  postoperatively (3)
• 2 of disease progression
• 1 following trauma 4 months post-op
• Thus the overall post operative mortality was 0

52
Conclusions

• The introduction of the SPAM clinic has provided
  a useful service to our trust
• Has allowed those deemed inappropriate for
  surgical intervention to be cancelled in good
  time
• Allows other treatment to be instigated where
  appropriate.

53
Conclusions

• Most encouragingly the overall operative risk in
  those deemed high risk is very low
• ? Our threshold is too high
• Hopefully preoperative risk stratification will
  be improved further with the introduction of CPET

54
Thank You For Listening