NEONATAL SOCIETY ABSTRACTS
Apnoea and periodic breathing
Presented at the Neonatal Society 2002 Summer Meeting (programme).
Hassan A, Ingram D, Milner A
Dept of Child Health, Guy's, King's and St Thomas' Hospitals, King's College, London.
Background: Apnoea occurring in association with periodic breathing (Periodic Apnoea, PA) is of interest as it represents cessation of breathing due to instability of respiratory control rather than just central suppression of breathing or reduction in chemoreceptor drive.
Aims: To assess the frequency of PA, how it related to the cycle time of the periodic breathing and how the pattern of PA changed with increasing age in preterm infants.
Methods: Twenty-six preterm infants (mean gestation: 29+4, range 25+1 to 32) were studied on 76 occasions, with approximately one week between studies. The infants were studied over four hour periods. Nasal airflow (thermistor), abdominal wall movement (Respitrace), saturation and heart rate (pulse oximeter) were recorded using a magnetic tape recorder. Apnoeas lasting at least 5 seconds were identified and classified. The cycle time for periodic breathing was obtained by measuring the time from one nadir to the next.
Results: 5875 apnoeas were identified. Of these, 67.4% occurred in association with periodic breathing (93.2% central, 6.1% mixed and 0.7% obstructive). The length of these apnoeas was directly proportional to the cycle time of the periodic breathing (p<0.001). The mean cycle time fell from 17.2 seconds at day 5 to 12.5 seconds at day 85 (p<0.01). Unlike isolated apnoeic attacks, PA increased with age, both for Pas greater than 10 seconds (p<0.05) and for Pas lasting 5 to 10 seconds (p<0.05).
Conclusion: Apnoea associated with periodic breathing accounted for 2/3 of all apnoea of prematurity. There was a significant relationship between the periodic breathing cycle and the length of these apnoeas. The increasing incidence of PA with age indicates an increasing instability i.e. less dampening of respiratory control.