Reduced inspiratory drive following laryngeal chemoreflex apnea during hypoxia.
Respiratory inhibition following laryngeal water administration was investigated by breath-by-breath analysis of inspiratory ventilation (VI) and central inspiratory drive (P0.1) in 15 unanesthetized lambs studied in 0.21 FIO2 (PaO2: 82-92 torr, PaCO2 41-43 torr) and in 0.1 FIO2 (Pao2 30-34 torr, PaCO2 32-33 torr). During the 30 sec period after stimulation, VI decreased significantly compared to prestimulation levels both in 0.21 FIO2 (-22, -21 and -18%) and in 0.1 FI(O2), (-16, -23 and -19%) at 5, 16 and 29 days, respectively. In contrast, P0.1 remained at prestimulation levels during normoxia in all age groups (1, 10 and 9%, NS), but decreased significantly during hypoxia (-11 and -13%, P < 0.05) at 16 and 29 days, respectively. Poststimulation apnea duration was significantly related to the decrease in VI (P < 0.001) but not to the change in P0.1. Laryngeal stimulation during hypoxemia/hypocapnia induces a prolonged decrease of central inspiratory drive in postneonatal lambs, a finding of potential significance for the mechanisms of sudden infant death syndrome.
Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232-2585, USA.
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Milerad
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HW
Sundell
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001049:Apnea / Q000097:blood / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000097:blood; D002628:Chemoreceptor Cells / Q000378:metabolism; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D007830:Larynx / Q000187:drug effects / Q000378:metabolism*; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012123:Pulmonary Ventilation / Q000502:physiology*; D012121:Respiration, Artificial; D012756:Sheep; D012815:Signal Processing, Computer-Assisted; D013990:Tidal Volume; D014867:Water
D014867:Water; D002245:Carbon Dioxide; D010100:Oxygen