Second place-resident clinical science award 1999: laryngeal chemoreflex severity and end-apnea PaO(2) and PaCO(2).
OBJECTIVE
The laryngeal chemoreflex (LCR) is a model for investigating the sudden infant death syndrome. The severity of the LCR-induced response may vary. This study examines the conditions under which recovery from the LCR-induced apnea occurs.


METHODS
Twenty-five piglets underwent normoxic laryngeal stimulation (Pao(2) > 70 mm Hg); 11 then underwent hypoxic stimulation (Pao(2) 50-65 mm Hg). Cardiovascular and respiratory responses were recorded.


RESULTS
Recovery Pao(2) was lower during profound responses (Pao(2) = 45.9 +/- 12.8 mm Hg) than during moderate (Pao(2) = 54.9 +/- 7.5 mm Hg) and mild (Pao(2) = 60.6 +/- 10.3 mm Hg) responses (analysis of variance [ANOVA], P = 0.05). Recovery PaCO(2) did not vary (ANOVA, P > 0.05). Blood pressure and O(2) saturation declined at faster rates with increasing severity of response (ANOVA, P < 0.05 for both).


CONCLUSIONS
Resumption of respiration after LCR-induced apnea is associated with a consistent level of PaCO(2). The severity of the response is associated with recovery PaO(2) levels.
Heman-Ackah
Y D
YD
Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis 55455, USA.
Goding
G S
GS
D000818:Animals; D000831:Animals, Newborn; D001049:Apnea / Q000503:physiopathology*; D001363:Awards and Prizes; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D000860:Hypoxia / Q000503:physiopathology*; D007830:Larynx / Q000503:physiopathology; D010036:Otolaryngology; D010100:Oxygen / Q000097:blood; D012119:Respiration; D013552:Swine
D002245:Carbon Dioxide; D010100:Oxygen