Sudden cerebral hypoperfusion enhances respiratory suppression in hypoxic newborn piglets.

The relationship between sudden cerebral hypoperfusion and sudden respiratory suppression was investigated in newborn piglets. A total of 11 experiments on five newborn piglets were divided into three groups: normoxic, hyperoxic and hypoxic. The sudden cerebral hypoperfusion was created by manual compression of the Arteria carotis communis and Vena jugularis interna. Respiratory suppression was calculated by measuring the duration of apnea and the percent reduction of respiratory amplitude. The means of apnea duration in normoxic and hyperoxic groups were 6.6 +/- 0.8 and 1.2 +/- 2.4 s, respectively, while two experiments on the hypoxic group showed 8.4 s and complete cessation of respiration in one of them. The per cent reductions of respiratory amplitude in the normoxic and hyperoxic groups were 23.3 +/- 8.5 and 17.6 +/- 11.7%, respectively. In the hypoxic group, one of two experiments showed a 22.7% reduction, which was equivalent to that of the normoxic group. We conclude that sudden cerebral hypoperfusion enhances respiratory suppression, especially when it coincides with hypoxia. The phenomenon may be one of the possible causes for a certain type of sudden infant death syndrome. Further study will be undertaken to elucidate the direct effects of the mechanism of cerebral hypoperfusion on respiratory suppression.