Acute anxiety predicts components of the cold shock response on cold water immersion before and after repeated immersion: implications for control of ventilation

Accidental cold-water immersion (CWI) triggers the life-threatening cold shock response (CSR) which is a precursor to sudden death on immersion. We have recently identified that acute anxiety accentuates the CSR in unhabituated participants; partially reverses the cardiac component of the response when acute anxiety is elevated after habituation has taken place (i.e. repeated, short, CWIs) and prevents habituation when present during habituation immersions; evidently, acute anxiety is integral to the CSR. From our database of CWIs we examined the predictive relationship between self-report anxiety ratings prior to immersion and the CSR during the first minute of CWI, when the CSR peaks, and therefore, is the most life-threatening period of acute immersion. We examined this relationship in unhabituated participants and those who underwent repeated CWI. Two analyses were undertaken. Study 1 included forty-eight unhabituated participants (34 male, 14 female; mean [SD] age 20.3 [1.7] years, height 1.75 [0.1] m, mass 76.2 [16.7] kg) who completed an initial, seven-minute immersion in to cold water (15 °C). Study 2 considered twenty-four of those participants (16 male, 8 female; age 20.4 [2.1] years, height 1.75 [0.1] m, mass 77.9 [17.2] kg) who completed a further four standardized CWIs followed by two counter-balanced immersions where anxiety was increased by deception prior to immersion (ANX) and the other acted as a control (CON). Anxiety (20 cm visual analogue scale) and cardiorespiratory responses (cardiac frequency [f_c], respiratory frequency [f_R], tidal volume [V_T], minute ventilation [V̇_E]) were measured. Stepwise multiple regression analyses were undertaken for components of the CSR predicted by the acute anxiety rating. Anxiety rating predicted the fc component of the CSR (p=0.02,r=0.436,r²=0.190) in unhabituated participants (i.e. study 1). In study 2 in the CON immersion anxiety rating predicted the f_R component of the CSR (p=0.03,r=0.566,r²=0.320) but predicted the f_c (p=0.03,r=0.443,r²=0.197) component in the ANX immersion. Acute anxiety prior to immersion predicts different components of the CSR before and after repeated CWI. We suggest raised anxiety levels reduce the voluntary capability to control ventilation during CWI.