Blood pressure and age associated with silent autonomic dysreflexia during urodynamic examinations in patients with spinal cord injury

Study design:An observational study.Objectives:To investigate the factors associated with silent autonomic dysreflexia (AD) during urodynamics (UD) in spinal cord injury (SCI) patients.Setting:Taichung city, Taiwan, ROC.Methods:Blood pressure (BP) and symptoms of AD were continuously monitored during UD, and systolic blood pressure (SBP) elevations >20 mmHg was considered an AD reaction. AD patients were divided into a symptomatic group and a silent group (without AD symptoms), and variables (basic demographic data, hemodynamic data and UD parameters) were compared.Results:A total of 42 patients, 21 in symptomatic and 21 in silent AD groups, were analyzed. Symptomatic group had significantly greater diastolic blood pressure (DBP) increment and rates of SBP/DBP changes (change of BP divided by duration) as compared to the silent group (29.5 vs 21.7 mmHg; 4.8 vs 2.3 mmHg min-1 and 2.8 vs 1.4 mmHg min-1) (P<0.05). The cutoff points of these three variables, determined by receiver operating characteristic analysis, are: DBP increment of 21 mmHg and rates of SBP/DBP change of 2.27 and 1.16 mmHg min-1. Age had a weak negative correlation with DBP change (Pearson's r=-0.377, P=0.048) and the silent group was significantly older than the symptomatic group (49.4 vs 40.1 years, P<0.05).Conclusion:Patients with more symptomatic AD tended to have significant DBP elevation and more rapid SBP/DBP increments, and this was negatively correlated with age. Aging decreases AD symptoms and the magnitude of DBP elevation, possibly through the mechanism of decreased baroreceptor sensitivity. BP monitoring during UD and other invasive procedures is strongly recommended, especially for elderly SCI patients.