The effects of airway closure in central apneas and obstructed respiratory efforts in mixed apneas in preterm infants

• Published in: Pediatric pulmonology 2009-03, Vol.44 (3), p.253-259
• Main Authors: Al-Sufayan, F., Bamehrez, M., Kwiatkowski, K., Alvaro, R.E.
• Format: Article
• Language: English
• Subjects: airway obstruction; Airway Obstruction - complications; Airway Obstruction - diagnosis; Airway Obstruction - physiopathology; apnea of prematurity; Biological and medical sciences; Bradycardia - etiology; Bradycardia - physiopathology; Chronic obstructive pulmonary disease, asthma; control of breathing; Diseases of mother, fetus and pregnancy; General aspects; Gestational Age; Gynecology. Andrology. Obstetrics; Humans; Infant, Low Birth Weight; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases - diagnosis; Infant, Premature, Diseases - physiopathology; Medical sciences; newborn; O2 saturation; Oximetry; Oxygen Consumption; Pneumology; Polysomnography; Pregnancy. Fetus. Placenta; Respiratory Mechanics; Sleep Apnea, Central - complications; Sleep Apnea, Central - diagnosis; Sleep Apnea, Central - physiopathology; Work of Breathing
• ISSN: 8755-6863; 1099-0496
• DOI: 10.1002/ppul.20989

Background Airway closure during central apnea could allow for better gas exchange. However, the return of inspiratory efforts against a closed airway may cause greater desaturation and prolongation of apnea. Objective To investigate the effect of patency of the airway and obstructed respiratory efforts on the length of apneas and the degree and slope of O2 desaturation and bradycardia. Methods All mixed apneas observed in 15 preterms were matched 1:2 with the longest central apneas in each infant. Central apneas were further classified using the amplified cardiac airflow oscillation in those with airway open and in those with airway closed. Results No differences were found in the length of apnea, slope of O2 desaturation, delay between the onset of apnea and onset of desaturation, lowest post‐apneic SpO2, and time of recovery of SpO2 between central apneas with and without airway closure. Although mixed apneas were significantly longer than central apneas, their initial central component was significantly shorter than the length of central apneas. In mixed apneas, the onset of O2 desaturation occurred faster, SpO2 decreased lower, and recovered slower compared with central apneas. The slope of O2 desaturation after the obstructed respiratory efforts was significantly greater than before the obstructed respiratory efforts. Conclusions In preterm infants: (1) airway closure during central apneas does not limit oxygen desaturation; (2) respiratory efforts against a closed airway prolong apnea and worsen the degree of desaturation and bradycardia. Although respiratory efforts are not necessary to induce airway closure, inspiratory efforts against a closed airway could trigger inhibitory cardio‐respiratory responses causing significant desaturation, bradycardia, and prolongation of apnea. Pediatr Pulmonol. 2009; 44:253–259. © 2009 Wiley‐Liss, Inc.