Hypotension Severity and Pattern Associate With Early Postoperative Cognitive Decline

In adults undergoing elective non-cardiac surgery under general anaesthesia, the presence of intraoperative hypotension did not correlate with early postoperative cognitive decline, whereas the severity, cumulative exposure, and specific pattern of blood pressure drops were associated with the outcome. A prospective observational cohort study evaluated whether a standard binary threshold of hypotension adequately captures cognitive risk or whether detailed exposure metrics provide more clinically meaningful insights into perioperative brain health.

Conducted at a tertiary teaching hospital in Ajman, United Arab Emirates, the investigation enrolled 261 adult surgical patients.

The investigators defined intraoperative hypotension as a relative decrease in mean arterial pressure exceeding 20 percent from the pre-induction baseline value. Blood pressure deviations were classified across severity tiers consisting of mild, moderate, and severe reductions, as well as distinct duration and pattern profiles comprising controlled single short episodes, prolonged episodes, and frequent short episodes. Across the cohort, 93.1 percent of patients met the criterion for intraoperative hypotension, presenting primarily with mild and moderate reductions, while no severe instances were recorded.

Early postoperative cognitive decline occurred in 3.1 percent of the surgical cohort. Overall, scores across both cognitive instruments dropped significantly in the immediate postoperative phase before demonstrating partial recovery by the first postoperative day. When analyzing the primary threshold, the simple occurrence of intraoperative hypotension showed no significant correlation with early postoperative cognitive deterioration.

In contrast, exploratory analyses revealed that both the severity and temporal pattern of low blood pressure were associated with early cognitive decline. Patients experiencing moderate hypotension, as well as those exhibiting either a single prolonged episode or frequent short episodes, had higher rates of early cognitive decline than individuals who experienced only a single short, controlled episode. Furthermore, patients diagnosed with early cognitive decline were significantly older and experienced significantly longer cumulative durations of hypotension.

The study authors concluded that relying on a conventional relative threshold of a 20 percent reduction in mean arterial pressure fails to predict cognitive complications, underscoring the necessity of evaluating exposure metrics rather than binary classifications. However, because all documented cognitive decline events occurred exclusively among the oldest patients in the cohort, collinearity and the limited number of events prevented causal inference, meaning these hypotension metrics could not be separated from the confounding effects of advanced age or confirmed as independent predictors.

The broader rationale for examining intraoperative hypotension centers on its established risks for myocardial and renal injury. Although these complications are well documented, the connection between intraoperative blood pressure drops and early postoperative cognitive decline has remained ambiguous because past studies relied on divergent definitions. By applying detailed classifications rather than an isolated threshold, the researchers addressed this ambiguity among adult patients undergoing elective non-cardiac procedures under general anaesthesia at a tertiary teaching hospital in Ajman.

To address the limitations of simple binary classifications, the protocol separated intraoperative hypotension into distinct tiers of severity and duration. Beyond recording a relative decrease in mean arterial pressure exceeding 20 percent from pre-induction baseline, the investigators classified episodes into mild, moderate, and severe categories. Hemodynamic patterns were also categorized into controlled short episodes, prolonged episodes, and frequent short episodes to capture cumulative exposure across the surgical procedure.

Neurocognitive performance was tracked at three predefined stages using the Mini-Mental State Examination and the Montreal Cognitive Assessment. By administering these evaluations before surgery, immediately after surgery, and on postoperative day 1, the researchers recorded the acute trajectory of cognition. Scores on both assessments dropped significantly immediately after surgery, but showed partial recovery by day 1. Early postoperative cognitive decline was identified in 3.1 percent of the 261 participants, whereas hypotension exceeding the 20 percent threshold occurred in 93.1 percent of patients, presenting primarily as mild or moderate cases with no severe instances.

Statistical findings demonstrated that simply reaching the 20 percent threshold did not correlate with early cognitive decline, whereas specific severity levels and patterns did. Similarly, patients with a single prolonged episode or frequent short episodes exhibited higher decline rates than those with a single short controlled episode. Patients diagnosed with cognitive decline also had significantly longer cumulative durations of hypotension, indicating that duration and recurring patterns were associated with adverse outcomes.

The researchers emphasized that these findings argue against relying on binary definitions of intraoperative hypotension in neurocognitive studies. A single relative cutoff fails to predict cognitive risk, making exposure metrics essential. However, the authors cautioned that these relationships must not be interpreted as evidence that hypotension severity or duration independently predicts cognitive decline. Because all decline events occurred exclusively among the oldest patients, advanced age acted as a critical confounder. Marked collinearity between age and hypotensive exposure, combined with the small number of events, prevented causal inference and precluded separating blood pressure from aging effects.

Subject of Research: Intraoperative hypotension exposure patterns and early postoperative cognitive decline

Article Title: Severity, duration, and pattern of intraoperative hypotension and early postoperative cognitive decline in adults undergoing non-cardiac surgery: a prospective observational cohort study

Article References: Firas Alnajjar, J., Gasmalla, G., Mahmoud, D., Ismail, M., & Safadi, E. (2026). Severity, duration, and pattern of intraoperative hypotension and early postoperative cognitive decline in adults undergoing non-cardiac surgery: a prospective observational cohort study. Frontiers in Medicine, 13, Article 1972338. https://doi.org/10.3389/fmed.2026.1972338

Image Credits: AI Generated

DOI: 10.3389/fmed.2026.1972338

Keywords: intraoperative hypotension, early postoperative cognitive decline, non-cardiac surgery, general anaesthesia, mean arterial pressure, Mini-Mental State Examination, Montreal Cognitive Assessment, postoperative cognitive dysfunction, perioperative neurocognitive disorders, hypotension severity, hypotension duration, pre-induction baseline, prospective observational study, elective surgery, age-related confounding, Thumbay University Hospital