EXTREMES IN HUMAN BREATH HOLD, FACIAL IMMERSION BRADYCARDIA

  • 1 January 1985
    • journal article
    • research article
    • Vol. 12  (2) , 183-190
Abstract
Although the average human response to apneic facial immersion in ice water is a reduction in heart rate from 70 to 45 beats/min, a small proportion of healthy subjects develop diving bradycardia to less than 20 beats/min. Healthy subjects performed resting, seated, 30-s mid-inspiratory breath hold, facial immersion in a basin of water. Heart rate dropped more when the water temperature was 1.degree. C than at 24.degree. C. Five subjects developed more when the water temperature was 1.degree. C than at 24.degree. C. Five subjects developed asymptomatic diving bradycardia to < 15 beats/min. One physically active individual consistently had dive heart rates as low as 5.6 beats/min.