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 (Pao2 > 70 mm Hg); 11 then underwent hypoxic stimulation (Pao2 50-65 mm Hg). Cardiovascular and respiratory responses were recorded. RESULTS: Recovery Pao2 was lower during profound responses (Pao2 = 45.9 ± 12.8 mm Hg) than during moderate (Pao2 = 54.9 ± 7.5 mm Hg) and mild (Pao2 = 60.6 ± 10.3 mm Hg) responses (analysis of variance [ANOVA], P = 0.05). Recovery Paco2 did not vary (ANOVA, P > 0.05). Blood pressure and O2 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 Paco2. The severity of the response is associated with recovery Pao2 levels.
Bibliographical noteFunding Information:
From the Department of Otolaryngology–Head and Neck Surgery, University of Minnesota; and the Department of Otolaryn-gology–Head and Neck Surgery, Hennepin County Medical Center. Supported by the Minnesota Medical Research Foundation. Presented at the Annual Meeting of the American Academy of Otolaryngology–Head and Neck Surgery, New Orleans, LA, September 26-29, 1999. Reprint requests: George S. Goding, Jr, MD, Department of Otolaryngology–Head and Neck Surgery, University of Minnesota, Box 396, Mayo Memorial Bldg, 420 Delaware St SE, Minneapolis, MN 55455. Copyright © 2000 by the American Academy of Otolaryngology– Head and Neck Surgery Foundation, Inc. 0194-5998/2000/$12.00 + 0 23/1/106710 doi:10.1067/mhn.2000.106710