The Effect of The Cold Pressor Test on Arterial Wave Reflection Magnitude and Timing in Young Healthy Adults

Sympatho-excitatory stimuli, such as the cold pressor test (CPT), increases microvascular resistance and brachial blood pressure. Cardiovascular responses to the CPT can predict cardiovascular risk. Previous research has demonstrated that surrogate measures of wave reflection (augmentation index) are increased during the CPT. However, this measure does not differentiate the effect of wave reflection magnitude vs. return time of the reflected waves. The purpose of this study was to test the hypothesis that the CPT would increase the amplitude of the backward pressure wave and result in an earlier return of wave reflection. Methods: Nine non-obese, non-hypertensive, healthy adults between the ages 18 – 40 years participated. For the CPT, participants submerged their hand in ice water for three minutes. Brachial blood pressure and arterial pressure waves were measured via applanation tonometry at baseline and during the last minute of the CPT. Wave separation analysis was performed to determine the maximal amplitude of forward and backward pressure waves as well as the reflected wave transit time using the centroid method. Reflection magnitude was calculated as ratio of backward relative to forward pressure wave amplitude. Results: In agreement with previous research, there was a significant increase in aortic systolic and diastolic blood pressure, as well as augmentation index (all, p<0.05). The novel finding was that despite no changes in the forward pressure wave amplitude (26±5 vs. 26±6 mmHg, p=0.81), there was a significant increase in the backward pressure wave amplitude (10±2 vs. 12±3 mmHg, p<0.05) as well as reflection magnitude (36±7 vs. 45±5%, p<0.01). Lastly, there was a trend for a shortened reflected wave transit time (316±55 vs. 246±60 ms, p=0.09). Conclusion: A sympatho-excitatory stimulus (i.e. CPT) in young healthy adults increased the amplitude of the reflected wave and tended to lead to an earlier arrival of wave reflections to the proximal aorta. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.