Modulation of cardiovascular autonomic function in a healthy male during cold pressor test resulted in neurocardiogenic syncope

Abstract

Sir,

The cold pressor test (CPT) is one of the recognized physiological evaluation techniques to assess cardiac autonomic functions.^[1] In this test, the subject immerses one of his hands up to wrist into ice cold water (4–6°C) for 1–6 min. Blood pressure (BP) and heart rate (HR) response to CPT is monitored continuously. In normal subjects, a vascular sympathetic response is increased during CPT resulting in increased peripheral resistance.^[2] The present case study reported loss of consciousness of a healthy Indian adult male while undergoing CPT.

A 29‑year‑old healthy, nonsmoker male having body weight, height and body surface area (BSA) of 75.9 kg, 176 cm and 1.96 m2 respectively, participated as a volunteer for the assessment of cardiac autonomic functions by cold pressor test. The temperature of the laboratory was maintained at about 25°C which was well within the comfort zone of human beings. The electrocardiography (ECG) of the subject was measured during rest in sitting posture for 5 min and during CPT for 3 min. The participant in sitting posture dipped his left hand up to the wrist into ice cold water at 4°C. The temperature of the water was maintained at 4–5°C throughout the CPT, by monitoring with a thermometer. A plastic tray of 6 cm height was used for cold water immersion, where ice cubes were mixed with normal tap water. Read more...