Effect of Intraoperative Arterial Hypotension on the Risk of Perioperative Stroke After Noncardiac Surgery: A Retrospective Multicenter Cohort Study

Abstract

BACKGROUND: Intraoperative cerebral blood flow is mainly determined by cerebral perfusion pressure and cerebral autoregulation of vasomotor tone. About 1% of patients undergoing noncardiac surgery develop ischemic stroke. We hypothesized that intraoperative hypotension within a range frequently observed in clinical practice is associated with an increased risk of perioperative ischemic stroke within 7 days after surgery. METHODS: Adult noncardiac surgical patients undergoing general anesthesia at Beth Israel Deaconess Medical Center and Massachusetts General Hospital between 2005 and 2017 were included in this retrospective cohort study. The primary exposure was intraoperative hypotension, defined as a decrease in mean arterial pressure (MAP) below 55 mm Hg, categorized into no intraoperative hypotension, short (<15 minutes, median [interquartile range {IQR}], 2 minutes [1–5 minutes]) and prolonged (≥15 minutes, median [IQR], 21 minutes [17–31 minutes]) durations. The primary outcome was a new diagnosis of early perioperative ischemic stroke within 7 days after surgery. In secondary analyses, we assessed the effect of a MAP decrease by >30% from baseline on perioperative stroke. Analyses were adjusted for the preoperative STRoke After Surgery (STRAS) prediction score, work relative value units, and duration of surgery. RESULTS: Among 358,391 included patients, a total of 1553 (0.4%) experienced an early perioperative ischemic stroke. About 42% and 3% of patients had a MAP of below 55 mm Hg for a short and a prolonged duration, and 49% and 29% had a MAP decrease by >30% from baseline for a short and a prolonged duration, respectively. In an adjusted analysis, neither a MAP <55 mm Hg (short duration: adjusted odds ratio [ORadj], 0.95; 95% confidence interval [CI], 0.85–1.07; P = .417 and prolonged duration: ORadj, 1.18; 95% CI, 0.91–1.55; P = .220) nor a MAP decrease >30% (short duration: ORadj, 0.97; 95% CI, 0.67–1.42; P = .883 and prolonged duration: ORadj, 1.30; 95% CI, 0.89–1.90; P = .176) was associated with early perioperative stroke. A high a priori stroke risk quantified based on preoperatively available risk factors (STRAS prediction score) was associated with longer intraoperative hypotension (adjusted incidence rate ratio, 1.04; 95% CI, 1.04–1.05; P < .001 per 5 points of the STRAS prediction score). CONCLUSIONS: This study found no evidence to conclude that intraoperative hypotension within the range studied was associated with early perioperative stroke within 7 days after surgery. These findings emphasize the importance of perioperative cerebral blood flow autoregulation to prevent ischemic stroke.

Pro-Con Debate: The Clinical (Ir)relevance of the Lower Limit of Cerebral Autoregulation for Anesthesiologists

“…In a cohort of 358,931 perioperative patients, of whom a total of 1553 (0.4%) experienced a stroke, no relationship was found with prolonged MAP <55 mm Hg, or a MAP decrease of >30%. 70 Evidence from prospective randomized trials is scarce. In one trial, patients on CPB were randomized to a higher (70–80 mm Hg) or lower (40–50 mm Hg) target for MAP.…”

Association Between Intraoperative Arterial Hypotension and Postoperative Delirium After Noncardiac Surgery: A Retrospective Multicenter Cohort Study

“…Analyses were adjusted for a priori-defined potential confounding variables based on available literature and clinical plausibility. 10,19,24 Potential confounding variables included patient demographics and comorbidities such as age, sex, body mass index (BMI), ASA physical status classification, diabetes mellitus, arterial hypertension, peripheral vascular disease, cerebrovascular disease, patent foramen ovale, smoking, depression, schizoaffective disorders, neurocognitive impairment, history of drug and alcohol abuse, as well as ischemic stroke or transient ischemic attack within 1 year before surgery. We further adjusted analyses for preoperative medications including benzodiazepines and antipsychotics as well as for intraoperative anesthesia-related factors and markers of procedural severity, including the admission type, emergency status, duration of surgery, high-risk surgery (transplant, general, vascular, or neurosurgery), and work relative value units (surgical work relative value units based on Current Procedural Terminology [CPT] codes).…”

“…This categorization was chosen based on previous reports and recent work from our group using this categorization. [16][17][18][19] In secondary analyses, we defined a decrease in MAP by >30% from baseline as the exposure variable as this relative decrease has been previously shown to be associated with adverse neurological outcomes. 20 The baseline MAP was defined as the MAP taken during preoperative evaluation at the preadmission testing (PAT) for patients undergoing anesthesia for surgery.…”

“…METHODS: Adult noncardiac surgical patients undergoing general anesthesia at 2 academic medical centers between 2005 and 2017 were included in this retrospective cohort study. The primary exposure was intraoperative hypotension, defined as the cumulative duration of an intraoperative mean arterial pressure (MAP) <55 mm Hg, categorized into and short (<15 minutes; median [interquartile range {IQR}], 2 [1-4] minutes) and prolonged (≥15 minutes; median [IQR], 21 [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] minutes) durations of intraoperative hypotension. The primary outcome was a new diagnosis of delirium within 30 days after surgery.…”

The association of nitrous oxide on length of stay in the postanesthesia care unit: a retrospective observational study

“…Intraoperative hypotension was defined as mean arterial pressure below 55 mm Hg and categorized as short (1-15 min) and prolonged ([15 min) duration. 15 dose, neostigmine dose, intravenous administered fluid volume, and transfused packed red blood cell units]). [16][17][18][19][20][21] Primary and secondary analyses…”