Mechanisms of Drowning in Children: Influence of Cold Shock Response on Repolarization Patterns and Arrhythmia Burden in Healthy Children

INTRODUCTION: While drowning plays a particularly important role in children, the data on the physiology of drowning in this population are scarce. Both the cold shock response and the development of arrhythmias within the context of an autonomic conflict may be of particular significance during drowning. The cold shock response has now been outlined by our working group, while the effect of cold water on cardiac repolarization remains unclear. This study aims to provide a more detailed examination of the effects of cold shock response in healthy children, focusing on changes in repolarization patterns and the development of arrhythmias to enhance the knowledge on drowning mechanisms in children. METHODS: Participants were first immersed up to the neck in warm water (34°C) and then in cold water (11°C), while skin temperature, heart rate and respiratory rate were continuously measured and ECG and Holter-ECG were recorded. RESULTS: Heart rate variability parameters were lower in cold water compared to warm water. In cold water, the Tp-Te interval was significantly shorter compared to baseline in air. Additionally, QT interval did not adequately adapt to the sudden increase in heart rate during cold water immersion. Despite premature contractions regardless of immersion, no arrhythmias were detected. CONCLUSION: The current study presents first data on repolarization patterns and arrhythmia burden in healthy children during the immersion into 11°C (52°F) cold water. Data showed, that cold water immersion represents a strong sympathetic stressor associated with mild QT hysteresis and a distinct influence on the transmural gradient of repolarization. Although no arrhythmias were detected during cold water immersion in healthy children, the cold shock response itself appears to have the potential to induce repolarization abnormalities in individuals with pre-existing conditions.