Physiological studies of the effectiveness of the human dive reflex in healthy subjects without arrhythmia
| Author | Sample size | Age range (years) | Study type | ‘Cold’ tool | Temperature (°C) | Apnoea employed | Duration (s) | History of previous SVT | Subject rhythm | HDR performance position |
| Arnold4 * | 58 | 10–71 | Prospective, randomised to various vagal manoeuvres | Ice water in plastic bag or facial immersion | 1 | Covered nose and mouth or apnoea during facial immersion | 30 | No | SR | Supine |
| Kaijser et al18 * | 15 | 60–80 | Mixed methods case control study | Iced water | Not stated | Breath holding during facial immersion | 10 | No | SR | Sitting |
| Furedy et al8 * | 48 | Adults (>18 but not stated) | Prospective interventional, non-randomised | Water | 10, 20, 40 | Breath holding during facial immersion | 40 | No | SR | Prone |
↵* 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.