Perioperative Risk Assessment

Samuel H. GayEfosa O. Ogiamien

Introduction• In order to assess a patients risk for intraoperative/postoperative

complications an anesthesiologist and/or surgeon must take into account many aspects. For instance– Patients Physiological Status (Preop, Intraop, and Postop)– The disease being modified in Surgery– The type of Surgery– The Institute in which one practices

• The 48 h and 30 d incidence of postoperative mortality was 0.57 % and 2.1% respectively. Higher ASA physical status scores, extremes of age, emergencies, perioperative adverse events and postoperative Intensive Care Unit admission were identified as risk factors.

• Due to the increasing number of co- morbidities in today’s patients many new systems have arisen to judge the risk of the surgery to the patient.

ASA Physical Status Classification

Table 13-1: American Society of Anesthesiologists Physical Status Classification*

• ASA 1 Healthy patient without organic, biochemical, or psychiatric disease. Excludes extremes of age.

• ASA 2 A patient with mild systemic disease. No significant impact on daily activity. Unlikely impact on anesthesia and surgery. Examples: mild asthma, well-controlled HTN, DM w/o renal disease, cigarette smoking w/o COPD, mild obesity, pregnancy.

• ASA 3 Significant or severe systemic disease that limits normal activity. Significant impact on daily activity. Likely impact on anesthesia and surgery. Examples: stable angina, old MI, controlled CHF, CRF, class 2 CHF.

• ASA 4 Severe disease that is a constant threat to life or requires intensive therapy. Serious limitation of daily activity. Major impact on anesthesia and surgery. Examples: end-stage disease, CRF on dialysis, acute MI, respiratory failure requiring mechanical ventilation.

• ASA 5 Moribund patient who is likely to die in the next 24 hours with or without surgery.

• ASA 6 Brain-dead organ donor.

* “E” added to the above classifications indicates emergency surgery, Available at www.asahq.org.

“Does ASA Classification Correlate With Outcomes Following Open and Endovascular Aortic Aneurysm Repairs?”

• Retrospective case-control study• Compared ASA classification and morbidity/mortality in

233 pt who had aortic aneurysm repairs (146 endovascular and 77 open repairs)

• In the open repair group, mortality and morbidity strongly correlated to the ASA class with higher mortality in ASA class 4 than class 3 patients (34% vs. 9%, p=0.006).

• In both the EVAR and the open groups, morbidity significantly increased with higher ASA class (EVAR group: 31% for ASA 3 and 56% for ASA 4, p <0.05) and (open group: 33% for ASA 3 and 100% for ASA 4, p <0.05).

Review Article: “American Society of Anesthesiologists Physical Status Classification”

• One study showed the following relationship b/t postoperative complication and ASA class• ASA 1: 0.41/1000• ASA 4/5: 9.6/1000• ASA 1E: 1/1000• ASA 4/5E: 26.5/1000

• Mortality rates varied significantly among different studies• ASA 1: 0-0.3%• ASA 2: 0.3-1.4%• ASA 3: 1.8-4.5%• ASA 4: 7.8-25.9%• ASA 5: 9.4-57.8%

ASA Physical Status Classification

• Limited to only the pt’s medical hx and physical/functional status

• Leaves out many other important risk factors like…– Type of surgery– Necessity of surgery (Emergency vs Elective)– Pt’s age and sex, Pt’s weight and social habits (drugs,

alcohol, tobacco)– Pregnancy– Airway assessment

ASA Physical Status Classification

• Use as a preoperative risk assessment is controversial

• In general, studies show increased risk of morbidity and mortality with higher ASA scores, however…

• Ambiguous– Provider Dependent– ‘Systemic’ (HTN, DM) vs ‘local’ disease (Fx’s, COPD,

MI, etc)

Goldman Cardiac Risk Index (1977)

• In 1977, Dr. Goldman and his colleagues came up with this system to assess risk of cardiac complications in relatively low risk surgical candidates

• Point value assigned to each of 9 clinical risk factors• 4 risk classes• Not used any more due to multiple limitations, including

complexity and changes in the perioperative care of patients

• Relative to ASA classification, it takes more time to calculate, it takes into account labs and type of surgery, and is usually not used in an emergency/ICU pt

Goldman Cardiac Risk Index (1977)

Revised (Goldman) Cardiac Risk Index (RCRI)

• Simplified version of Goldman’s original system • 6 independent predictors of major cardiac

complications, which similarly divides pts into 4 risk groups

• Still used today• Recommended by the ACC/AHA for cardiac risk

assessment in surgical candidates• Note: since only 1/3 of perioperative deaths are due

to cardiac causes, RCRI is not a good predictor of all-cause mortality

Revised (Goldman) Cardiac Risk Index (RCRI)

Estimation of cardiac risk using RCRI

“Preoperative pulmonary risk stratification for noncardiothoracic surgery” by the ACP and ASA

• Showed that certain co-morbidities, procedures, and lab values lead to higher odds ratio of pulmonary complications postoperatively– ASA class> II: 2.55-4.87 – Advanced age: 2.09-3.04– CHF: 2.93– COPD: 1.79– functionally dependent: 1.65-2.51– Emergency surgery: 2.21– AAA repair: 6.90– Thoracic Surgery: 4.24– Abdominal Surgery: 3.01– Upper abdominal surgery: 2.91– Vascular surgery: 2.10– Albumin < 35 g/ml: 2.53– General Anesthesia: 1.83– (Hip surgery is not a risk factor)

Pathophysiological sequalae of surgical stress response

• Cardiovascular and SNS activation– Increased myocardial oxygen demand– Tachycardia, Dysrhythmia, angina, myocardial infarction

• Respiratory– Decrease TV due to pain– Hypoxemia, hypercapnia, atelectasis, pneumonia

• Endocrine– Hyperglycemia, Protein catabolism– Increased cortisol, HTN, immunocompromised

• Immunologic– Inflammation, decreased immune function, sepsis

• Gastrointestinal– Ileus

• Renal– Urinary retention, renal failure

• Hematologic– Increased Platelet and fibrinogen production– Thromboembolic events

• Central Nervous system– Insomnia, anxiety

Summary

• 3 elements must be assessed to determine risk of adverse events in a surgical pt1. Presence of systemic diseases (HTN, DM) and

lung/heart medical conditions (COPD, hx of MI, CVA, etc)

2. Functional status (or exercise capacity)3. Type of surgery

References• Miller, Ronald D., and Manuel C. Pardo. Basics of anesthesia. 6th ed.

Philadelphia: Elsevier/Saunders, 2011.• Singh, K., and Danny Yakoub. “Does ASA Classifcation Correlate with

Outcomes following Open and Endovascular Aortic Aneurysm Repairs?” Staten Island, New York. 2012.

• Daabiss, Mohamed. “American Society of Anesthesiologist Physical Status Classification.” Indian Journal of Anesthesia. Vol 55. India. 2011.

• Shammash, J., and Stephen Kimmel. “Estimation of Cardiac risk Prior to Noncardiac Surgery.” Evidence-Based Clinical Decision Support at the Point of Care, UpToDate. N.p., n.d. Web 20 Sept. 2013. http://www.uptodate.com/contents/estimation-of-cardiac-risk-prior-to-noncardiac-surgery?detectedLanguage=en&source=search_result&search=cardiac+risk+assessment&selectedTitle=1%7E150&provider=noProvider