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Cerebral and ventilatory depression during hypoxia in anaesthetized newborn guinea‐pigs
Author(s) -
Yuan ShiZeng,
Runold Michael,
Lagercrantz Hugo
Publication year - 1995
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.1995.tb13578.x
Subject(s) - medicine , hypoxia (environmental) , tidal volume , anesthesia , cerebral hypoxia , ventilation (architecture) , respiratory system , respiration , respiratory minute volume , respiratory rate , heart rate , oxygen , blood pressure , anatomy , chemistry , mechanical engineering , organic chemistry , ischemia , engineering
The effects of hypoxia on ventilation and cerebral activity were studied in urethane‐anaesthetized newborn guinea‐pigs. Ventilation was measured by a pneumotachograph, and cerebral activity by a cerebral function monitor (CFM). All animals were subjected to either 9% O 2 or 6% O 2 in N 2 for 10 minutes or until apnoea occurred. Hypoxia produced a biphasic response in ventilation, that is, an increase followed by a decrease. The initial increase was attributed to the elevation of the respiratory rate, whereas the tidal volume showed a pure decline. The respiratory rate reached its peak at 3 minutes of hypoxia (170 ± 12% during 9% O 2 and 169 ± 12% during 6% O 2 ). Cerebral activity during both 9 and 6% O 2 breathing showed a small increase followed by a decrease. In the group subjected to 9% O 2 the maximum CFM activity increased to 114 ± 8% of the control level and the minimum activity increased to 113 ± 7%, while in the group subjected to 6% O 2 the maximum CFM activity increased to 104 ± 5% and the minimum CFM activity to 101 ± 3%. The depression of CFM activity was more pronounced with 6% O 2 than with 9% O 2 . Regression analysis showed a linear correlation between ventilation and cerebral activity during both 9 and 6% O 2 breathing. The results suggest that hypoxic ventilatory depression may be the consequence of cerebral depression produced by acute severe hypoxia.