Postoperative hypotension in patients discharged to the intensive care unit after non-cardiac surgery is associated with adverse clinical outcomes

Abstract

Background: The postoperative period is critical for a patient's recovery, and postoperative hypotension, specifically, is associated with adverse clinical outcomes and significant harm to the patient. However, little is known about the association between postoperative hypotension in patients in the intensive care unit (ICU) after non-cardiac surgery, and morbidity and mortality, specifically among patients who did not experience intraoperative hypotension. The goal of this study was to assess the impact of postoperative hypotension at various absolute hemodynamic thresholds (≤ 75, ≤ 65 and ≤ 55 mmHg), in the absence of intraoperative hypotension (≤ 65 mmHg), on outcomes among patients in the ICU following non-cardiac surgery.

Methods: This multi-center retrospective cohort study included specific patient procedures from Optum® healthcare database for patients without intraoperative hypotension (MAP ≤ 65 mmHg) discharged to the ICU for ≥ 48 h after non-cardiac surgery with valid mean arterial pressure (MAP) readings. A total of 3185 procedures were included in the final cohort, and the association between postoperative hypotension and the primary outcome, 30-day major adverse cardiac or cerebrovascular events, was assessed. Secondary outcomes examined included all-cause 30- and 90-day mortality, 30-day acute myocardial infarction, 30-day acute ischemic stroke, 7-day acute kidney injury stage II/III and 7-day continuous renal replacement therapy/dialysis.

Results: Postoperative hypotension in the ICU was associated with an increased risk of 30-day major adverse cardiac or cerebrovascular events at MAP ≤ 65 mmHg (hazard ratio [HR] 1.52; 98.4% confidence interval [CI] 1.17-1.96) and ≤ 55 mmHg (HR 2.02, 98.4% CI 1.50-2.72). Mean arterial pressures of ≤ 65 mmHg and ≤ 55 mmHg were also associated with higher 30-day mortality (MAP ≤ 65 mmHg, [HR 1.56, 98.4% CI 1.22-2.00]; MAP ≤ 55 mmHg, [HR 1.97, 98.4% CI 1.48-2.60]) and 90-day mortality (MAP ≤ 65 mmHg, [HR 1.49, 98.4% CI 1.20-1.87]; MAP ≤ 55 mmHg, [HR 1.78, 98.4% CI 1.38-2.31]). Furthermore, we found an association between postoperative hypotension with MAP ≤ 55 mmHg and acute kidney injury stage II/III (HR 1.68, 98.4% CI 1.02-2.77). No associations were seen between postoperative hypotension and 30-day readmissions, 30-day acute myocardial infarction, 30-day acute ischemic stroke and 7-day continuous renal replacement therapy/dialysis for any MAP threshold.

Conclusions: Postoperative hypotension in critical care patients with MAP ≤ 65 mmHg is associated with adverse events even without experiencing intraoperative hypotension.

Keywords: 30-day mortality; 90-day mortality; Acute kidney injury (AKI); All-cause mortality; Critically ill patients; Dialysis; Intensive care setting; Major adverse cardiac or cerebrovascular events (MACCE); Mean arterial pressure; Postoperative hypotension.

Fig. 1

Patient cohort attrition diagram. The final study cohort comprised 3185 procedures of 3169 unique patients. MAP, mean arterial pressure

Fig. 2

Cumulative incidence of postoperative hypotension for overall surgeries and the top 10 surgeries, among patients discharged to the ICU for 48 h after non-cardiac/non-obstetric surgery. Patients included had no preceding IOH (MAP ≤ 65 mmHg). The incidence of lowest POH value recorded per patient by MAP thresholds of ≤ 55 mmHg, ≤ 65 mmHg, ≤ 75 mmHg and > 75 mmHg is shown for overall surgeries and the 10 most common surgery types and overall (craniotomy most common, knee prosthesis least common). Due to rounding, categories will not always add to 100%. surgeries in the top 10 cohort: AMP, limb amputation; CHOL, gallbladder surgery; COLO, colon surgery; CRAN, craniotomy; FUSN, spinal fusion; FUSN-LAM, spinal fusion laminectomy; FX, open reduction of fracture; HPRO, hip prosthesis; KPRO, knee prosthesis; THOR, thoracic surgery (non-cardiac, non-vascular); POH, postoperative hypotension

Fig. 3

Adjusted hazard and sub-distribution hazard ratios for critical care patients with postoperative hypotension. Data shown for procedures (n = 3185) without preceding IOH (≤ 65 mmHg) at three absolute POH thresholds (≤ 55, ≤ 65 and ≤ 75 mmHg). *Significant after applying Bonferroni adjustment (p value of ≤ 0.05/3 or 0.016). POH, postoperative hypotension; MAP, mean arterial pressure; MACCE, major adverse cardiovascular or cerebrovascular events; AIS, acute ischemic stroke; AKI, acute kidney injury; AMI, acute myocardial infarction, Adj, adjusted; CRRT, continuous renal replacement therapy; HR, hazard ratio; SDHR, sub-distribution hazard ratio; CI, confidence interval