The cold face test (diving reflex) in clinical autonomic assessment: methodological considerations and repeatability of responses

Abstract

1. Cold stimulus applied to the face causes bradycardia and peripheral vasoconstriction (i.e. the diving reflex), and has been suggested as a test of the autonomic pathways involved. The purpose of this study was to define standard procedures for conducting the test and analysing the responses to the cold face test, to evaluate variability in responses between subjects and within subjects when the same test is repeated, and to examine its usefulness in clinical autonomic assessment. 2. Sixteen (nine female, seven male) healthy adult (21-35 years old) subjects were used. Cold stimulus was applied with gel-filled compresses. Forehead temperature under the compress as an indication of stimulus magnitude, heart rate, blood flow in the finger, toe and calf by venous occlusion plethysmography, and systolic and diastolic blood pressure were monitored. Three protocols were carried out in which the temperature (0, 5, 10, 15 degrees C), placement (whole face, unilateral, forehead) and duration (20, 40, 60, 120 s) of the cold compress application were varied. 3. The data indicate that 0 degrees C compresses applied bilaterally for 40 s produced the maximum bradycardia and peripheral vasoconstriction. No subject found this test to be obnoxious, but a 120 s application was objectionable to some subjects. This cold face test resulted in 22%, 72%, 59% and 44% reductions in heart rate and blood flow to the finger, toe and calf, respectively. There was significant between-subject variability, but good consistency in responses to tests repeated in the same subject on different days, at different times of day and in different seasons.(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained increases in blood pressure elicited by prolonged face cooling in humans

“…It is well established that face cooling elicits a pressor response in humans for up to 180 s (1,3,7,11,14,15,18,19,21,22). Data from the present study extend these findings and show that face cooling-induced increases in blood pressure can be sustained for at least 15 min (Fig.…”

“…It is well known that face cooling elicits robust increases in sympathetic nerve activity (11,15,21) and, thus, vascular resistance in the peripheral (11,16), visceral (6,19), and cerebral (3) vasculatures. Ultimately, these responses elevate blood pressure (1,3,7,11,14,15,18,19,21,22), as cardiac output remains largely unaffected by face Values are expressed as means Ϯ SD. RMSSD, root mean square of successive differences of the R-R interval; PU, perfusion units.…”

“…Cooling of the forehead and cheeks evokes a similar, yet less pronounced, response in humans (1,3,7,11,14,15,18,19,21,22), which occurs secondary to stimulation of the cold afferents of the trigeminal nerve (10,17). Face cooling in humans simultaneously stimulates the parasympathetic and sympathetic nervous systems, evoking bradycardia and peripheral vasoconstriction (1,3,7,11,14,15,18,19,21,22). In humans, reductions in heart rate are not sufficient to reduce cardiac output (3).…”

“…In humans, reductions in heart rate are not sufficient to reduce cardiac output (3). Therefore, blood pressure increases as a result of systemic peripheral vasoconstriction (1,3,7,11,14,15,18,19,21,22).…”

“…The hemodynamic responses to face cooling in humans have only been studied up to 180 s in duration (1,3,7,11,14,15,18,19,21,22). Thus, it is unknown whether the relative hypertensive responses elicited by face cooling, in addition to the temporal dynamics of parasympathetic and sympathetic activation, are sustained beyond 180 s. The diving reflex in diving mammals and birds persists for the duration of the dive (4).…”