Incidence, Course, and Characteristics of Hydralazine-Associated Tachycardia During Phase I Postanesthesia Recovery.

Purpose: This study aims to characterize the development of tachycardia after intravenous hydralazine administration during Phase I recovery.

Design: Retrospective observational study design.

Methods: The medical records of 745 adult surgical patients who were administered hydralazine during Phase I recovery between January 1, 2010 and December 31, 2014 were electronically reviewed to characterize episodes of tachycardia.

Findings: Seventy patients (94.0 cases per 1,000 administrations; 95% confidence interval = 74.0 to 117.2) developed tachycardia with a median increase of 23 beats per minute (bpm; interquartile range [IQR] = 15 to 37), a maximum rate of 106 bpm (IQR = 103 to 111; range = 101 to 131), and duration of 28 minutes (IQR = 5 to 86). The median onset of tachycardia was 43 minutes (IQR = 20 to 93), with 40% occurring after the first hour. Tachycardia was associated with female sex (P < .001), younger age (P < .001), and those with lesser comorbidities (P < .009).

Conclusions: A sizeable proportion of cases of tachycardia associated with hydralazine administration occurred after 1 hour, suggesting that these patients who may not tolerate a faster heart rate warrant longer duration of monitoring.