Cold-induced vasodilation: A meta-analysis

Area of Science:

• Physiology
• Environmental Health
• Vascular Biology

Background:

• Cold-induced vasodilation (CIVD) is a physiological response to cold exposure, characterized by intermittent blood flow to extremities.
• Despite extensive research, a comprehensive synthesis of CIVD factors and mechanisms is lacking.

Purpose of the Study:

• To conduct a meta-analysis and narrative review to synthesize existing research on cold-induced vasodilation.
• To identify factors influencing CIVD onset and magnitude and to explore underlying physiological mechanisms.

Main Methods:

• Meta-analysis of 80 studies involving hand immersion in cold water (<20°C) for 30 minutes.
• Narrative literature review of individual factors and proposed CIVD mechanisms.

Main Results:

• The weighted average onset time for CIVD was 7.9 minutes, with mean finger temperature at 10.0°C.
• CIVD onset was longer for whole-hand immersion, larger body surface area, and males; it was shorter with higher ambient temperatures, in cold-adapted populations, and with increasing age.
• Onset time showed a weak negative correlation with finger temperature during immersion.

Conclusions:

• CIVD onset is primarily triggered by local tissue temperature, while its magnitude depends on sympathetic activity.
• Proposed mechanisms involve impaired noradrenaline transfer or nitric oxide release, requiring further investigation.
• Future research should include more females and older adults due to their underrepresentation.