Between-visit Reproducibility of Cerebrovascular and Cardiovascular Reactivity During the Cold Pressor Test

The cold pressor test (CPT) is a painful test used to assess cardiovascular and cerebrovascular reactivity. Past studies examined between-visit reproducibility of cardiovascular reactivity during the CPT but not cerebrovascular reactivity. Therefore, we performed a retrospective analysis to test the hypothesis that cerebrovascular responses during the CPT would not differ and would have moderate relative agreement between visits. Fifty young adults free from overt disease, not taking pain-modifying medications, completed two trials ≥48 hours apart. We measured middle cerebral artery blood velocity (MCAv) via transcranial Doppler ultrasound, beat-to-beat blood pressure (BP) via photoplethysmography, and end-tidal CO2 (ET-CO2) via capnography during a five-minute baseline and two-minute CPT. We calculated reactivity as the change (Δ) from baseline to the first and second minute of the CPT. There were no between-visit differences in baseline mean BP, mean MCAv, or ET-CO2 (Ps≥0.24). There were no between-visit differences for Δmean MCAv (Ps>0.75) or Δmean BP (Ps>0.07). Relative agreement between visits was moderate for Δmean MCAv (intraclass correlation coefficient (ICC): Δmin-1=0.68, Δmin-2=0.72) and moderate/good Δmean BP (ICC: Δmin-1=0.65, Δmin-2=0.80). Our data suggest that Δmean MCAv to the CPT isnot different between visits while the relative agreement is similar to BP reactivity. Further, relative agreement was higher during minute two than minute one for key variables. These data extend our knowledge of the reproducibility of CPT reactivity. These findings will inform future research aimed at comparing cardiovascular and cerebrovascular reactivity as health markers between groups.