A Retrospective Observational Study of Post-Induction Low Systolic Blood Pressure and Associated Patient and Perioperative Factors in Infants Undergoing General Anesthesia for Inguinal Hernia Repair

Abstract

Background: Infants are at risk of cerebral hypoperfusion from low blood pressure during anesthesia. We conducted a retrospective observational study to determine the patient and perioperative factors associated with low systolic blood pressure (SBP) in healthy infants. Methods: We obtained perioperative data of 266 infants aged 0–6 months who underwent inguinal hernia repair between January 2015 and March 2019 at our institution. SBP was analyzed during two phases: the preparation phase (20 min before procedure start until incision) and the surgical phase (15 to 35 min after procedure start). Low SBP was defined as a value lower than two standard deviations below the 50th percentile for a phase- and weight-specific reference value. Results: Low SBP was observed in 11% (29/265) and 5% (13/259) of patients during the preparation and surgical phases, respectively. Neuromuscular blockade use was associated with normal SBP in both phases (regression coefficient β = 6.15 and p = 0.002, regression coefficient β = 6.52 and p < 0.001, respectively). SBP was more strongly associated with weight than with age (ratio of adjusted standardized regression coefficient = 2.0 in both phases). After controlling for covariates, patients given neuromuscular blockade had significantly fewer low SBP measurements during the preparation phase (regression coefficient β = −1.99 and p < 0.001). Conclusions: With respect to patient factors, in healthy infants under general anesthesia, weight was more strongly associated with SBP than age. A neuromuscular blocking agent administered during anesthesia induction was associated with fewer low SBP measurements in the preparation phase.