# Time-of-Day-Dependent Post-Induction Hypotension and Personalized Hemodynamic Management in Emergency Spine Surgery: A Retrospective Pre–Post Cohort Study

## TL;DR

This study shows that personalized hemodynamic management can reduce hypotension after anesthesia in emergency spine surgery, especially in morning cases.

## Contribution

The study introduces a personalized hemodynamic management bundle that effectively reduces post-induction hypotension burden in emergency spine surgery.

## Key findings

- PHM reduced post-induction hypotension incidence from 43.8% to 33.0%.
- PHM decreased the time-weighted average MAP below target by 2.3 mmHg.
- PHM reduced the area under the curve of MAP below 65 mmHg by 40%.

## Abstract

Background and Objectives: Post-induction hypotension (PIH) is common in emergency spine surgery and may vary by time of day. We evaluated whether a personalized hemodynamic management (PHM) bundle was associated with reduced PIH and hypotension burden. Materials and Methods: We conducted a single-center retrospective pre–post cohort study of adults undergoing emergency decompressive or stabilizing spine surgery under general anesthesia. The PHM bundle included documentation of an individualized pre-induction MAP target (default 65 mmHg; higher for selected high-risk phenotypes), dynamic assessment of fluid responsiveness, and proactive vasopressor use (norepinephrine initiated at induction in prespecified high-risk patients), with continuous BP trajectory monitoring. PIH was defined as mean arterial pressure (MAP) < 65 mmHg or a ≥30% decrease from pre-induction MAP within 20 min. We used 1:1 propensity score matching (caliper 0.2) and provider-clustered logistic regression in the matched cohort. Results: Among 312 eligible patients (usual care n = 200; PHM n = 112), PIH varied by time of day, with the highest incidence in morning cases (46.2%; p = 0.041). After matching, 224 patients (112 per group) were analyzed. PHM was associated with lower PIH (43.8% vs. 33.0%; adjusted odds ratio 0.62; 95% CI: 0.41–0.94; p = 0.024). PHM reduced time-weighted average (TWA) MAP below target (5.7 ± 4.2 vs. 3.2 ± 3.6 mmHg; mean difference (MD) −2.3 mmHg; 95% CI −3.3 to −1.3; p = 0.001) and area under MAP < 65 mmHg (ratio 0.62; 95% CI 0.50–0.78; p < 0.001). Norepinephrine-equivalent dose was higher (Δ + 20 μg; p = 0.005) while rescue phenylephrine boluses were fewer (Δ − 1; p < 0.001); crystalloid volume was similar (p = 0.151). Conclusions: In emergency spine surgery, PIH showed time-of-day variation, and PHM implementation was associated with reduced PIH and hypotension burden.