Sustained Attention and Types of Dynamics of Cardiovascular Reactivity during a Short-Term, Human Whole-Body Exposure to Cold Air

Abstract

Background: Despite global warming and the improvement of personal protective equipment against unfavorable climatic factors, cold remains an important environmental challenge for humans. The aim of the work was to reveal the peculiarities of the dynamics of cardiovascular parameters in humans with short-term, whole-body exposure to cold air, depending on the parameters of voluntary attention. Methods and Results: The study involved 28 healthy male volunteers aged between18 and 21 years, born and living in Arkhangelsk. Testing to assess sustained attention parameters using the Toulouse-Pierón Attention Test with the measurement of the index of accuracy (C, units) (the ability to voluntary concentration) and processing speed (V, units), had been previously performed. Subsequent stages of the study included recording the studied parameters before (Stage 1), during 10-minute exposure to the cold air (Stage 2), and 5 minutes after cold exposure (Stage 3). The registration of indicators in Stages 1 and 3 was carried out indoors at an air temperature of +20 °C. The registration of indicators in Stage 2 was carried out in a cold chamber at -20 °C. Determining the body temperature in the ear canal (Tear, °C) and on the skin of the dorsum of the right hand (Tskin, °C) was performed using a B.Well WF-1000 medical electronic infrared thermometer. Parameters of blood pressure (SBP and DBP) and heart rate variability (HRV) were evaluated. As a result of cluster analysis, 2 groups were identified: Group 1 (n=14) and Group 2 (n=14). In Group 2, the index V was significantly lower than in Group 1(P=0.02). In Group I, Tskin in Stage 1 was significantly higher than in Group 2 (P=0.03). In Stage 2, Tskin decreased in both groups, but lower Tskin values (P=0.001) were recorded in Group 2 than in Group I. In Stage 2, there was a statistically significant increase in SBP in Group 2 (P=0.01). In Group 1, initial SDNN and all HRV spectral indices were significantly higher than in Group 2. In Stage 2, there was a significant increase in SDNN in both groups. However, in Group 2, we found a statistically significant increase in VLF in Stage 2 (P=0.01), while in Group I this indicator remained unchanged. In Stage 3, HRV parameters in Group 1 recovered to baseline values, while in Group 2, HRV parameters remained elevated relative to baseline values. Conclusion: Individuals with high processing speed and preserved attention span have higher vagal activity and skin temperature. When such individuals are exposed to cold, they experience a moderate increase in BP and baroreflex response. In persons with a reduced speed of information processing but with sufficient accuracy of attention, there is a more pronounced mobilization of regulation resources on the part of the cardiovascular, neurovegetative systems to maintain the core temperature of the body.