Preoperative Evaluation: General Internal Medicine

1
Preoperative EvaluationGeneral Internal
Medicine

• Ken Locke MD, FRCPC
• April 4, 2006

2
Outline

• Preoperative Cardiac Evaluation
• Preoperative Pulmonary Evaluation
• DVT Prophylaxis

3
Perioperative Cardiac Evaluation
4
Objectives

• Understand process of perioperative cardiac
  evaluation
• Recognize clinical predictors of risk
• Evaluate patients need for further testing
• Understand risk reduction strategies

5
Perioperative Cardiac Evaluation

• Each patient is evaluated by surgeon,
  anaesthetist, and others to determine risk of
• Perioperative Death
• Perioperative MI
• Emphasis is on identifying elements that INCREASE
  risk above baseline

6
Perioperative Cardiac Evaluation

• Questions to ask
• What makes this patient unique re. risk?
• What is the surgery?
• What is the overall risk (patient procedure)?
• Does it matter?
• Can we reduce the risk?

7
Clinical Evaluation

• All evaluations begin with an individuals
  clinical information
• What characteristics of this patient contribute
  to cardiac risk?

8
Case 1

• You have admitted a 74 year old man with acute
  cholecystitis. Your plan is to treat with
  antibiotics and defer surgery if possible. The
  patient has a history of type 2 diabetes on OHAs,
  severe OA of the knees, and HTN. He takes an ACE
  inhibitor and ASA. Physical examination is
  normal. ECG shows inferior Q waves.

9
Clinical Evaluation - Shortcut

• May be avoided if the surgery is a true emergency
  and will proceed regardless of assessment
• In this case, move to identifying and managing
  postoperative complications

10
Clinical Evaluation

• General approach a search for any evidence of
  cardiovascular disease, with an emphasis on
  identifying factors that increase chance of
  perioperative endpoints
• Detailed cardiovascular history, physical, and
  ECG emphasis on quantifying severity of symptoms

11
Functional Capacity Assessment

• All assessments are coloured by the patients
  general ability to exercise
• ANY exercise limitation (OA, COPD, PVD, Stroke)
  increases perioperative risk somewhat
• Reduced functional capacity makes it harder to
  determine absence of coronary symptoms
• General threshold is gt4 METs to reduce risk
• May make testing necessary to clarify risk

12
Patient Assessment

• Patients who have had coronary revascularization
  lt5 years prior and have remained stable No
  increased risk, may proceed
• Patients with recent coronary evaluation if
  not increased risk, and symptoms unchanged No
  increased risk, may proceed

13
Patient Assessment, continued

• Patients requiring further assessment
• Use an evidence-based index to identify
  predictors of perioperative risk
• AHA guidelines approach presented here
  Identifying Major, Intermediate and Minor
  Predictors of Risk

14
Identify Major Clinical Predictors

• Unstable Coronary Syndromes Current ACS, Class
  III or IV angina
• Decompensated CHF
• Significant arrhythmias
• Severe valvular heart disease (particularly AS
  severe or critical)
• No testing is required to determine that these
  patients are at increased risk move on to
  management of the risk

15
Identify Intermediate Clinical Predictors

• Mild angina Class I or II stable angina
• Prior MI by history or ECG
• Prior CHF or compensated LV dysfunction
• Diabetes mellitus requiring pharm. Rx
• Renal insufficiency (stable creatininegt175)
• These factors may not increase risk importantly
  unless higher risk surgery or poor functional
  status testing may then clarify risk estimate

16
Identify Minor Clinical Predictors

• Advanced age (gt75)
• Abnormal ECG (eg. PVCs)
• Rhythm other than sinus
• Low functional capacity
• History of stroke
• Uncontrolled hypertension
• These factors only increase risk when surgical
  risk is very high, or multiple factors coexist
  with reduced functional capacity testing rarely
  needed

17
Summary of Risk Estimation

• Major clinical predictors
• Above average risk, testing not needed to
  determine risk
• Intermediate clinical predictors
• May be above average risk if reduced functional
  capacity testing may clarify
• Minor clinical predictors
• Mostly average risk, unless multiple with reduced
  functional capacity testing rarely helpful

18
A Word about Old MI

• How old is old?
• Formerly within 6 months the test of time
• Now can be as little as 6 weeks, provided
• All post-MI risk stratification done
• Revascularization done if appropriate
• No active symptoms for at least 1 month

19
Our Patient

• You have admitted a 74 year old man with acute
  cholecystitis. Your plan is to treat with
  antibiotics and defer surgery if possible. The
  patient has a history of type 2 diabetes on OHAs,
  severe OA of the knees, and HTN. He takes an ACE
  inhibitor and ASA. Physical examination is
  normal. ECG shows inferior Q waves.

20
Our Patient

• No history of revascularization, never evaluated
  for CAD
• No major predictors
• Intermediate predictors
• Likely has CAD MI on ECG no symptoms
• DM requiring OHAs
• Minor clinical predictor
• HTN
• Poor exercise capacity because of OA unable to
  walk up stairs
• Overall Above average risk for this procedure
  testing may clarify this

21
What is the Surgery?

• After evaluating the patient, consider the nature
  of the procedure you are contemplating

22
Surgical Risk

• Inherent procedural risk plays a major role in
  overall level of risk
• Minor procedures require less precise risk
  estimation than major ones
• Within each surgical specialty, some procedures
  are higher risk than others
• Aortic procedures carry the highest risk
  eye/ear/GU/gyne procedures carry the lowest

23
Surgical Risk

• Emergency surgery always increases risk
  compared to non-emergency procedures
• Definition No time to make any significant
  adjustments to patients condition before
  proceeding

24
Our Patient

• Elective cholecystectomy is the planned procedure
  low to moderate risk in general
• If emergency cholecystectomy is necessary,
  average risk would be higher
• More impetus to defer surgery in this above
  average patient

25
Combining Risks

• The patients overall risk is the determining
  factor in how to proceed
• At this point, testing may be considered, if the
  risk estimation actually matters

26
Does This Risk Matter?

• Will a precise risk estimate result in a
  significant change in perioperative management?
• Most important for elective procedures, less so
  for urgent (eg. cancer) or emergency procedures
• Default is to make a conservative assumption
  above average risk, and proceed
• Testing can improve informed consent and guide
  postoperative management

27
When to Test?

• When the decision to proceed will depend on risk
  estimate
• When stakes are higher high risk OR, high risk
  of no OR
• When clinical information suboptimal poor
  functional capacity
• Testing may demonstrate lower risk than estimated

28
Testing Modalities

• Persantine Sestamibi/Thallium SPECT or Dobutamine
  Stress Echo are equally efficacious
• Most reassuring result is Normal
• Most high risk result is severe widespread
  ischemia with LV dilatation and reduced EF in
  response to stress
• Results in between are not as helpful the worse
  the ischemia, the higher the perioperative risk

29
Testing Modalities

• The most definitive test is coronary angiography
• Rarely done to estimate perioperative risk
• More often as part of CAD management plan

30
Our Patient

• If he requires an emergency cholecystectomy,
  should be presumed above average risk and managed
  as such
• For elective chole, testing may improve his
  understanding of the risk/benefit of procedure -
  debatable

31
Managing Risk

• All patients have the potential for perioperative
  risk reduction
• Most effective Defer/cancel surgery
• Alternative Less risky procedure if available
• Both of these may increase overall risk if the
  surgical disease is severe and a change in
  procedure will result in poorer outcome
• Management of risk B-blocker, revascularization

32
Beta Blockade - Evidence

• 2 RCTs demonstrate reduced perioperative risk
  when B-blockers given
• Mangano et al. Atenolol in lower risk patients
  (CAD or risk factors) going for medium risk
  procedures some benefit
• Poldermans et al. Bisoprolol in higher risk
  patients (proven CAD, many 3vd) for higher risk
  procedures more benefit

33
Beta Blockade
Beta Blocker Effectiveness
Poldermans
?
Mangano
Overall Risk (Patient and Procedure)
34
Beta-Blockade - Practice

• In practice, may give B-blocker for risk
  reduction in almost all patients with some degree
  of perioperative risk
• Asthma or bradycardia risk are main
  contraindications

35
Revascularization

• Currently not recommended solely to improve
  perioperative risk
• RCT Only effect is to delay surgery!
• Main indication is when CAD is a greater priority
  than the surgical problem and revascularization
  would be recommended anyway

36
Our Patient

• If goes to emergency chole, would B-block pre-
  and post-operatively
• Consider for post-operative workup, especially if
  any cardiac complication
• If chole is elective, test preoperatively and
  B-block unless has prognostically poor test
  result then would debate whether CAD is greater
  priority than GB disease

37
Recap of Perioperative Cardiac Evaluation

• Questions to ask
• What makes this patient unique re. risk?
• What is the surgery?
• What is the overall risk (patient procedure)?
• Does it matter?
• Can we reduce the risk?

38
Examples

• 65 year old man going for laminectomy for
  disabling back pain
• Hx of DM, MI 20 years ago
• Currently can walk 20 feet maximum
• ECG Normal sinus rhythm, no ischemia

39
Examples

• 78 year old woman 3 months after minor R sided
  stroke, scheduled for L carotid endarterectomy
  for 80 stenosis
• Has class I angina (after 40 minutes brisk
  walking 2 or 3 miles)
• No other medical illness
• ECG Normal

40
Examples

• 89 year old woman going for TURBT
• Class III angina stable for years
• Can walk across the room, not further
• HTN and DM
• ECG A. fib, lateral T wave inversion

41
Perioperative Pulmonary Evaluation
42
Case 2

• You are planning an adrenalectomy on a 56 year
  old woman with adrenal adenocarcinoma. She has a
  history of productive cough for 10 years, and
  becomes short of breath after 1 flight of stairs.
  She has a 40 pack year history of smoking. She
  has never had any pulmonary tests.

43
Case 2

• How can you predict whether she will have
  pulmonary complications of surgery?

44
Perioperative Pulmonary Evaluation

• Purpose Predict severe respiratory
  complications of non-pulmonary surgery
• Separate indices for respiratory failure (failure
  to extubate, requiring reintubation, death) and
  postoperative pneumonia, similar risk factors
• A newly evolving literature

45
Predictive Index (Arozullah et al.)

• Important predictors
• Type of surgery AAA, thoracic, upper abd, neck,
  neurosurgery
• Emergency surgery, surgery requiring GA
• Age gt 60 (esp. age gt 80)
• Functional status (dependence)
• Albumin lt 30 g/L
• Hx of COPD (but PFTs do not improve this!)
• BUN gt 11 mmol/L
• Preoperative transfusion

46
Predicting Pulmonary Complications

• Some of these predictive factors are clearly
  markers for patients at higher risk (eg.
  transfusion, BUN, albumin)
• Others relate directly to effects of surgery on
  abnormal lung physiology
• Further testing is rarely helpful in adding to
  predictive ability

47
Testing for Lung Disease

• CXR Routine adds no predictive power
• May be useful to document baseline findings
• ABG No indication for predicting risk
• Again, may be useful for future comparisons in
  patients at risk for hypercarbia
• PFTs No extra predictive information
• However, may be helpful for intraoperative and
  postoperative management therefore often done

48
Risk Reduction Manoeuvres

• As usual, the most effective is to avoid surgery
  or alter technique
• Smoking cessation long term likely reduces
  risk, short term likely increases it
• Lung expansion IS, DBC, Chest PT, CPAP
• Conflicting evidence in studies with low
  methodologic quality may help for high risk
  patients

49
Our Patient

• Has a history strongly suggestive of COPD (mixed
  chronic bronchitis and emphysema picture)
• Going for abdominal surgery under GA
• Otherwise has no other risk predictors

50
Risk Reduction

• Consider whether surgical technique can be
  altered
• Consider change in anaesthetic technique
• Post-operative management is main intervention
  slow extubation, ICU monitoring
• Preoperative ABG and PFTs may assist post-op
  decisions

51
DVT Prophylaxis
52
DVT Prophylaxis

• Best reference is Geerts et al, Chest supplement
  2004 (read online)
• A spectrum of risk
• As usual, risk is related to patient and
  procedural factors
• A variety of regimens for various risk settings

53
Patient Risk Factors

• Age
• Immobility/stroke/paralysis (esp. cord injury)
• Previous VTE
• Cancer
• Thrombophilic disorder
• Trauma to pelvis, hip, leg
• Nephrotic syndrome
• Peripartum period

54
Procedure Risk Factors

• Site of procedure (Abdomen, pelvis, hip, leg,
  spine)
• Surgical technique
• Duration of procedure
• Type of anaesthetic
• Degree of post-op immobilization
• Presence of infection

55
Risk and Outcomes

• Highest risk patients can be found to have up to
  80 incidence of calf DVT if untreated and
  screened postop
• Approx. half will have clinical sequelae of any
  kind
• 10 will have symptomatic PE
• Approx. 5 will have fatal PE

56
Prophylaxis is Indicated

• Important issue is choosing the appropriate
  regimen based on combination of patient/procedure
  risk
• Choices
• LDUH (eg. 5000 U SC q12 8 h)
• Adjusted dose heparin sc
• LMWH 2500 5000 U SC OD
• Elastic Stockings/Intermittent Pneumatic
  Compression
• Full coumadin anticoagulation
• Full LMWH anticoagulation

57
Limitations

• Very few head-to-head comparisons in all surgical
  situations
• Some regimens are clearly inferior, eg. LDUH in
  hip surgery
• Small differences between coumadin and LMWH
  except in major leg trauma
• Duration of Rx is usually until ambulation occurs
  but may be longer