Predictors of Post-induction Hypotension for Patients With Pulmonary Hypertension

Abstract

Purpose The purpose is to identify predictors of post-induction hypotension (PIH) during general anesthesia in a population of patients with varying degrees of pulmonary hypertension (PH). Methods This is a single-center, retrospective, observational study of perioperative data obtained via electronic health records from patients with PH undergoing surgery over a five-year period. Baseline patient characteristics, peri-induction management variables, and pre-induction mean arterial pressure (MAP) were statistically analyzed using Kruskal-Wallis rank sum tests, Pearson's chi-squared tests, and logistic regression analysis to identify risk factors for PIH. We further assessed the relationship between PH and PIH using propensity score matching. Primary outcomes include a percent decrease in post-induction blood pressure as well as a post-induction nadir with a threshold of 55 mm Hg. Results Eight hundred fifty-seven patients in the cohort stratified by severity of PH reveal that advanced age (p < 0.001), higher BMI (P = 0.002), higher American Society of Anesthesiologists (ASA) score (P = 0.001), and renal and cardiac comorbidities (P < 0.001) are associated with PH severity. None of our tested parameters were significantly predictive for PIH in patients with PH. Right heart failure was found to be weakly and non-significantly predictive of PIH in patients with PH (P = 0.052, odds ratio [OR] = 1.116). Diabetes (P = 0.007, OR = 0.919) and maintenance of spontaneous ventilation (P = 0.012, OR = 0.925) were associated with decreased rates of PIH. Conclusion Hypotension after induction of general anesthesia in patients with PH is a serious problem, yet statistically significant risk factors were not identified. History of diabetes and preservation of spontaneous ventilation had a significant but weak effect of decreasing rates of PIH. This pilot study was limited by retrospective design and warrants further analysis with a prospective cohort.

Keywords: anesthesia; mean arterial pressure; post-induction hypotension; pulmonary hypertension; surgical risk factors.

Figure 1. Severity of pulmonary hypertension (PH) delineated by pulmonary artery systolic pressure (PASP)

Patients included in this study are discretized according to the severity of PH based on a combination of PASP, right ventricular function and hypertrophy, yet the measured PASP alone provides similar delineation between categories with minimal overlap (indicated by the brown regions).

Figure 2. Propensity score matching demonstrates no significant difference (P = 0.29) between patients with high and low PASP

(A) Matching across several covariates produced 116 patients in each exposure and control groups with similar propensity scores. (B) The empirical quantile-quantile (eQQ) plots show the successful elimination of outliers during the matching process.