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Sedation with promethazine profoundly affects spontaneous airway protection in sleeping neonatal piglets
G M McKelvey1, E J Post, H E Jeffery
1Department of Animal Science, University of Sydney, New South Wales, Australia.
Insights
Promethazine medication in infants may increase risks of sleep apnea and reduce airway protection. Continued use over days can dangerously impair these mechanisms, warranting caution in infant sedation.
Area of Science:
- Neonatal physiology
- Pharmacology
- Sleep medicine
Background:
- Phenothiazine use in infants is linked to adverse events like sleep apnea and SIDS.
- Promethazine is a common antihistamine used in pediatric care.
Purpose of the Study:
- To investigate the cumulative effects of promethazine on airway protection and cardiorespiratory responses in neonatal piglets.
- To compare these effects in naturally sleeping versus sedated piglets.
Main Methods:
- 42 healthy neonatal piglets were studied over three consecutive days.
- Sedated piglets received promethazine (1.5 mg/kg, p.o.) prior to recordings.
- Physiological and radiological recordings were made during natural and sedated sleep.
Main Results:
- Promethazine increased sleep time and active sleep.
- It significantly decreased swallowing and arousal.
- Promethazine increased both central and obstructive sleep apnea, with cumulative effects observed by day three.
Conclusions:
- Low-dose promethazine significantly alters sleep, airway protection, and cardiorespiratory responses in piglets.
- Prolonged promethazine use may severely impair airway protective mechanisms.
- Caution is advised when using promethazine for infant sedation.
Abstract:
1. Phenothiazine use in infants has been implicated in apparent life-threatening events, sleep apnoea and Sudden Infant Death Syndrome. 2. The aim of this study was to investigate the cumulative effects of a commonly used antihistamine medication containing promethazine on airway protective mechanisms and cardiorespiratory responses in 42 healthy neonatal piglets (21 naturally sleeping, 21 sedated sleeping). 3. Sedated piglets were given 1.5 mg/kg, p.o., promethazine 2 h prior to each recording session. Control animals slept naturally with no sedative given. On three consecutive days in all piglets, physiological recordings were made during sleep; on at least one of these days, simultaneous physiological and radiological observations were made. 4. Following sedation, sleep time and time in active sleep were increased significantly (P < 0.01). The spontaneous occurrence of swallowing, arousal, body movement, gastrooesophageal reflux and apnoea was compared between naturally and sedated sleeping piglets. Sedation with promethazine significantly decreased the spontaneous occurrence of swallowing (P < 0.05) and arousal (P < 0.05) and increased the occurrence of both central (P < 0.05) and obstructive sleep apnoea (P < 0.0001). 5. By the third day, a cumulative effect of promethazine was seen; the rate of swallowing and body movement significantly decreased (P < 0.01). 6. In summary, a low dose of promethazine profoundly altered sleep characteristics, airway protective mechanisms and cardiorespiratory responses in normal healthy sleeping piglets. Continued use of promethazine over several days may attenuate airway protective mechanisms to a potentially life-threatening degree. Our findings support continued caution in the use of promethazine-containing medications for the sedation of infants.