Periodic breathing induced on demand in awake newborn lamb

Canet, Emmanuel, Jean-Paul Praud, and Michel A. Bureau. Periodic breathing induced on demand in awake newborn lamb. J. Appl. Physiol. 82(2): 607–612, 1997.—Spontaneous periodic breathing, although a common feature in fullterm and preterm human infants, is scarce in other newborn mammals. The aim of this study was to induce periodic breathing in lambs. Four 10-day-old and two P CO 2 ( Pa CO 2 ). Arterial P O 2 ( Pa O 2 ) was set and maintained at the desired level by changing inspired O2 fraction and providing O2 through a small catheter into the “apneic” lung. At a critical Pa O 2 / Pa CO 2 combination, the four 10-day-old lambs exhibited periodic breathing that could be initiated, terminated, and reinitiated on demand. In the 2-day-old lambs with low chemoreceptor gain, periodic breathing was hardly seen, regardless of the trials done to find the critical P O 2 / P CO 2 combination. We conclude that periodic breathing can be induced in lambs and depends on critical Pa O 2 / Pa CO 2 combinations and maturity of the chemoreceptors.