Table 3

Physiological studies of the effectiveness of the human dive reflex in healthy subjects without arrhythmia

AuthorSample sizeAge range (years)Study type‘Cold’ toolTemperature (°C)Apnoea employedDuration (s)History of previous SVTSubject rhythmHDR performance position
Arnold4 *5810–71Prospective, randomised to various vagal manoeuvresIce water in plastic bag or facial immersion1Covered nose and mouth or apnoea during facial immersion30NoSRSupine
Kaijser et al18 *1560–80Mixed methods case control studyIced waterNot statedBreath holding during facial immersion10NoSRSitting
Furedy et al8 *48Adults (>18 but not stated)Prospective interventional, non-randomisedWater10, 20, 40Breath holding during facial immersion40NoSRProne
  • * These studies used bradycardia measured from resting heart rate as a clinical outcome measure to describe the magnitude of vagal tone in healthy subjects with no arrhythmia present.

  • HDR, human dive reflex; SR, sinus rhythm; SVT, supraventricular tachycardia.