Exertional Hypotension in Spinal Cord Injury

Abstract

To assess blood pressure (BP) response to continuous maximal arm ergometry in patients with spinal cord injury (SCI). Cross-sectional analysis of data collected for a prospective study of functional electrical stimulation in patients with SCI. Short-term rehabilitation hospital. Twenty individuals with SCI; 4 cervical (C6 to C8), 10 high thoracic (T1 to T6), and 6 low thoracic (T7 to T12). Each subject performed continuous maximal arm ergometry with expired gas analysis. Blood pressure was measured using a technician-assisted protocol. The BP at maximal exercise was compared with the highest submaximal BP reached during the test (delta BP = final BP minus highest submaximal BP). All 20 subjects had a negative delta BP (mean +/- SD; -22.8 +/- 12.1 mm Hg) for mean BP and 19 of 20 had a negative delta BP (-25.8 +/- 14.4 mm Hg) for systolic BP. The delta BP was not significantly related to maximum exercise parameters, resting BP, or level of lesion. Four able-bodied subjects and six wheelchair-bound individuals without SCI showed no exertional hypotension. Repeated testing on the four able-bodied subjects showed excellent reproducibility for mean BP (coefficient of variation [CV] = 3.6 percent; r = 0.98; p < 0.01) and systolic BP (CV = 2.2 percent; r = 0.99; p < 0.01) using this protocol. These data describe, for the first time to our knowledge, that exertional hypotension is present in all individuals with SCI during continuous arm ergometry. Further studies are needed to clarify the mechanisms responsible for this phenomenon and to evaluate the long-term consequences for individuals with SCI.