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

<i>Background and Objectives</i>: 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. <i>Materials and Methods</i>: 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. <i>Results</i>: Among 312 eligible patients (usual care <i>n</i> = 200; PHM <i>n</i> = 112), PIH varied by time of day, with the highest incidence in morning cases (46.2%; <i>p</i> = 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; <i>p</i> = 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; <i>p</i> = 0.001) and area under MAP < 65 mmHg (ratio 0.62; 95% CI 0.50-0.78; <i>p</i> < 0.001). Norepinephrine-equivalent dose was higher (Δ + 20 μg; <i>p</i> = 0.005) while rescue phenylephrine boluses were fewer (Δ - 1; <i>p</i> < 0.001); crystalloid volume was similar (<i>p</i> = 0.151). <i>Conclusions</i>: In emergency spine surgery, PIH showed time-of-day variation, and PHM implementation was associated with reduced PIH and hypotension burden.