Characterization of heart rate changes associated with autonomic dysreflexia during penile vibrostimulation and urodynamics

Study design Secondary data analysis. Objectives To characterize autonomic dysreflexia (AD) associated heart rate (HR) changes during penile vibrostimulation (PVS) and urodynamic studies (UDS). Setting University-based laboratory. Methods We analyzed blood pressure (BP) and HR data, recorded continuously, from 21 individuals (4 females; median age 41 years [lower and upper quartile, 37; 47]; median time post-injury 18 years [7; 27]; all motor-complete spinal cord injury (SCI) except one; cervical SCI = 15, thoracic [T1–T6] SCI = 6), who underwent PVS (11/21) or UDS (10/21). Results Overall, 47 AD episodes were recorded (i.e. PVS = 37, UDS = 10), with at least one AD episode in each participant. At AD threshold, bradycardia was observed during PVS and UDS in 43% and 30%, respectively. At AD peak (i.e., maximum increase in systolic BP from baseline), bradycardia was observed during PVS and UDS in 65% and 50%, respectively. Tachycardia was detected at AD peak only once during UDS. Our study was limited by a small cohort of participants and the distribution of sex and injury characteristics. Conclusions Our findings reveal that AD-associated HR changes during PVS and UDS appear to be related to the magnitude of systolic BP increases. Highly elevated systolic BP associated with bradycardia suggests the presence of severe AD. Therefore, we recommend cardiovascular monitoring (preferably with continuous beat-to-beat recordings) during PVS and UDS to detect AD early. Stopping assessments before systolic BP reaches dangerously elevated levels, could reduce the risk of life-threatening complications in this cohort.