To the "Annual meeting of the Swiss Society of Pediatrics, June 2006, Berne
Children have a higher hypoxic ventilatory response than their fathers
Kriemler S, Zehnder M, Kohler M, Bloch K, Brunner HP, Boutellier U
Introduction: Chemoreceptor sensitivity plays an important role in the short-term adaptation to high altitude (HA). Decreased ventilatory response to hypoxia (HVR) is a risk factor for the development of high altitude pulmonary edema and possibly of acute mountain sickness (AMS). It is not clear, however, whether HVR is different in prepubertal children and adults nor whether there is a hereditary influence. Isocapnic HVR was therefore measured in 20 fathers (mean age 44.0±4.2y) and their prepubertal children (mean age 10.7±1.1y) at low altitude (450m) and on day 1 and 2 of HA (3450m) using the partial rebreathing technique. After 15 min of resting ventilation, three levels of hypoxia (PETO2 60, 55, 50 Torr) were randomly induced and kept stable (±2 Torr) for 2 min with 5 min of recovery in between. PCO2 was kept constant at ±2 Torr of values while breathing room air. HVR is expressed as increase in minute ventilation per decrease in saturation corrected for body weight. AMS was measured by Lake Louise Questionnaire. Results: AMS occurred in 8 children and 7 adults. HVR was significantly higher in children than in adults irrespective of altitude (0.020±0.010, 0.020±0.011, 0.024±0.012 vs. 0.012±0.007, 0.014±0.011, 0.018±0.012 ml*kg-1*min-1*%-1 at 450m, day 1 and 2 of 3450m, respectively, all p<0.0005). Only adults significantly increased their HVR on day 2 of HA (p<0.05). There was significant clustering of HVR within families (p<0.05). Individuals with AMS did not show a lower HVR than those without AMS.
Conclusion: Children have a higher HVR than their fathers which does not protect them from AMS. HVR seems to be genetically influenced.
This study was supported by the Swiss Federal Council of Sports
