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Bradycardic response during submersion in infant swimming
E Goksör1, L Rosengren, G Wennergren
1Department of Paediatrics, Göteborg University, Queen Silvia Children's Hospital, Sweden.
Insights
The infant diving response, characterized by bradycardia, persists beyond 6 months of age. This study confirms its presence and gradual decline with maturation in healthy infants.
Area of Science:
- Physiology
- Infant Development
- Cardiovascular Reflexes
Background:
- The diving response, involving bradycardia, apnea, and vasoconstriction, is documented in human infants.
- This reflex typically diminishes with age, often reported to disappear by six months.
Purpose of the Study:
- To analyze physiological events during natural infant diving.
- To describe how the diving response changes with infant maturation.
Main Methods:
- Studied 36 full-term healthy infants during supervised infant swimming diving exercises.
- Monitored heart rate changes during submersion and post-dive recovery.
Main Results:
- All infants exhibited an immediate heart rate decrease upon submersion, averaging a 25% reduction.
- Bradycardia was sustained during dives and often followed by tachycardia.
- A decline in reflex bradycardia with increasing age was observed (p=0.03), but the response remained evident beyond six months.
Conclusions:
- The study confirms the presence of a diving response in infants, mediated by vagal activity.
- While the bradycardic response wanes with age, it remains significant in infants older than previously reported.
Unlabelled:
The diving response involves reflex bradycardia, apnoea and peripheral vasoconstriction and is known to exist in human infants. The response diminishes with increasing age and has been reported to disappear by the age of 6 mo. This study was performed to analyse the physiological events during natural diving of full-term healthy infants and describe how these events alter with maturation. Thirty-six infants were studied during diving exercises in infant swimming. All of the infants who participated showed an immediate decrease in heart rate when submerged. On average, the heart rate decreased by 25% (range -5.0% to -50.7%, p <0.0001). The bradycardia was sustained during the dive and for some seconds afterwards. The response was often followed by a tachycardia as the bradycardia ceased. A decline of reflex bradycardia was observed with increasing age (p = 0.03), but the response was still clearly evident in infants over the age of 6 mo.
Conclusion:
This study demonstrates the existence of a diving response in infants, which includes an immediate bradycardic response, suggesting vagal mediation. Although the bradycardic response gradually decreases, the study shows that a clear-cut response exists in children older than has previously been reported.