The effect of the cold pressor test on arterial wave reflection amplitude and timing in young healthy adults

Abstract

Sympathoexcitatory stimuli, such as the cold pressor test (CPT), increase vascular 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 amplitude and return time of the reflected wave. 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: Twelve 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. 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 (28.16.8 vs. 28.19.4 mmHg, p=0.997), there was a significant increase in the backward pressure wave amplitude (10.82.7 vs. 12.85.4 mmHg, p=0.043) as well as reflection magnitude (386 vs. 455%, p=0.001). Lastly, there was a trend for a shortened reflected wave transit time (332.465 vs. 28860.1 ms, p=0.02). Conclusion: A sympathoexcitatory stimuli (i.e. CPT) in young healthy adults increased the amplitude of the backward pressure wave and tended to lead to an earlier arrival of wave reflections to the heart.