The Impact of the Cold Pressor Test on Inter-arm Differences in Blood Pressure.

A large inter-arm difference (IAD+; ≥10mmHg between arms at rest) in blood pressure (BP) at rest is linked to cardiovascular risk, and exercise can change this difference. As mechanisms for IAD are elusive, unique physiological stimuli may provide insight towards a better understanding of this phenomenon. The cold pressor test (CPT) has a potent effect on BP and acts primarily through sympathetic nervous system (SNS) stimulation, though the effects of SNS stimulation on IAD are unknown. Therefore, the purpose of the present study was to examine the effects of the CPT on IAD. BP was monitored simultaneously using two automated, auscultatory monitors (SunTech Tango) and a non-invasive hemodynamic device (Physioflow). Participants completed a CPT test, including a 15-minute rest, three pre-test BP measurements (averaged), and a three-minute water immersion (3°C; measurements at 30-sec and 2-min). Descriptive statistics were calculated, and a repeated measures ANOVA test used to compare both the absolute and relative IAD responses. The CPT induced an average absolute increase in IAD of 4.0 mmHg at 30-sec and 6.7mmHg at 2-min across all participants (P<0.05). Differences in both the absolute and relative IAD responses to the CPT were noted between IAD- and IAD+ individuals (P<0.05). Despite a consistent HR response to the CPT between groups, stroke volume was lower in IAD+ participants at 30-sec and 2-min. Sympathetic stimulation via the CPT induced changes in both the inter-arm difference in blood pressure and hemodynamics in young, apparently-healthy individuals.