Perioperative Stroke in Noncardiac, Nonneurosurgical

Surgery Ng et al, Anesthesiology 2011; 115:879-90

Presented by Paul Larsen

Stroke Definitions

Stroke - Focal or global neurologic deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours

TIA - <24 hours

Covert Stroke - Asymptomatic ischemic event detected with imaging

Stroke Incidence

In cardiac, neurologic, and carotid surgery, the incidence is 2.2-5.2%

Other procedures have a range of 0.05-4.4%

Differences in patient population, changing clinical practice over 40 year study design, diagnostic tests, and duration of follow up may account for the large variance in reported stroke rates

Outcomes

12.6% mortality rate in non-surgical strokes

Perioperative stroke mortality ranges from 26% in general surgery to 87% in patients with a previous stroke

Pathophys

Pathophys

The majority of perioperative strokes occur after the second postoperative day

Only 5.8% of strokes are thought to have occured during surgery

Cardiothoracic surgery related strokes are 60% embolic

Other surgeries have a 68% thrombotic etiology of the stroke

Why Thrombosis?

Post-op endothelial dysfunction?

General anesthetics impair endothelial function

Withholding antiplatelet/anticoagulant agents may aggrevate surgically induced hypercoaguability

Who is at risk?

Comorbidities:

Age, history of stroke, atrial fibrillation are among the most important risk factors

Others include COPD, PVD, DM

Who is at risk?

Type of Surgery

Hip arthoplasty, peripheral vascular surgery have a higher incidence of stroke than knee arthroplasty or general surgery

Head and neck surgery increases risk by 0.2-5%

Who is at risk?

B-blockers - increase in non-fatal stroke, hypotension, and bradycardia in patients undergoing noncardiac surgery

It is unclear if there is causation, and no temporal relationship between the stroke and hypotension has been defined.

Risk modification

Timing elective surgery after a recent stroke

Acute stroke impairs cerebral autoregulation so blood flow becomes passively dependent on perfusion pressure

Occurs within 8 hours of a stroke, can last 2-6 months

Recommend delaying nonurgent surgery for at least 1-3 months

Risk modification

A fib:

If pre-existing, continue antiarrhythmic or rate-controling agent perioperatively

Correct post-op electrolyte imbalances and fluid volume

Risk modification

Anticoagulants:

Perioperative stroke management

ID at risk patients and make an early diagnosis

Non-contrast CT within 25 minutes, consider thrombolysis, correct hypotension, fever

ASA is the only oral antiplatelet agent found to be beneficial