Inhibitory effects of repeated hyperoxia on breathing in newborn mice

¹ INSERM U676, Hôpital Robert-Debré, 48 Boulevard Sérurier, 75019 Paris, France; and AP-HP, Hôpital Raymond Poincaré, Service de Physiologie, 104 av Raymond Poincaré, 92380 Garches, France
² INSERM U676, Hôpital Robert-Debré, 48 Boulevard Sérurier, 75019 Paris, France; and AP-HP, Hôpital Robert-Debré, Service de Réanimation Pédiatrique, 48 Boulevard Sérurier, 75019 Paris, France
³ INSERM U676, Hôpital Robert-Debré, 48 Boulevard Sérurier, 75019 Paris, France
⁴ Faculté de Médecine d'Amiens, 3 rue des Louvels, Amiens 80036, France

^* To whom correspondence should be addressed. E-mail: f.lofaso{at}rpc.ap-hop-paris.fr.

	Abstract

Brief oxygen therapy is commonly used for resuscitation at birth or for preventing hypoxemia before procedures in neonatal period in term and premature newborn infants. However, O₂ may severely depress breathing, especially when administered repeatedly. The aim of this study was to test the effects of repeated hyperoxia on breathing control in newborn mice.

We randomly assigned 97 Swiss mice to O₂ or air on postnatal day 0, 1, or 2. Each pup in the O₂ group was subjected to four hyperoxic tests (100% O₂ for 3 min followed by 12 min normoxia), whereas pups in the air group were maintained in normoxia. Breathing variables were measured using flow-through barometric plethysmography.

Oxygen significantly decreased VE because of a decrease in respiratory rate. This decrease became significantly larger with repeated exposure (P<0.0005) and ranged from -17% to -26% for all ages combined. Furthermore, hyperoxia increased total apnoea duration, as compared to the baseline value (P<0.03).

In newborn mice, repeated hyperoxia increasingly depressed breathing. This finding further supports a need for stringent control of O₂ therapy, most notably repeated oxygen administration, in neonatal period in term and premature newborn infants.

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