Rhythms and complexity of respiration during sleep in pre-term infants.
The aim of this study is to test rhythmic and complex properties of respiratory control in former ventilated, pre-term infants during quiet and active sleep. The children had a higher risk for sudden infant death due to bronchopulmonary dysplasia (BPD). Twelve infants suffering from BPD and 12 control infants, matched regarding their post-conceptional age, were examined polygraphically during quiet (QS) and active sleep (AS). The respiratory rate (RR), the ratio (LF/HF) between the low-frequency power (LF) and the high-frequency power (HF) of the spectra of the thoracic respiratory effort, and the frequency of the dominant peak within LF (LFF) and HF (HFF) were computed. The correlation dimension (D2) of the respiratory signal was calculated to determine the complexity of the respiratory control. The transcutaneous pO2 (tcpO2) and pCO2 and the oxygen saturation (sO2) were analysed. Infants with BPD had significantly higher RR and HFF during QS (median: BPD 48 breaths min-1; control 32 breaths min-1). tcpO2 and sO2 were significantly lower in the BPD group. No differences were found in LF/HF, LFF or D2 between groups, either in QS or in AS. D2 ranged between 1.8 and 3.8, showing significantly higher values during AS. LFF was found to be lower during active sleep (AS 0.04-0.05 Hz; QS about 0.06 Hz). We propose that in infants with BPD the lower lung compliance and the higher resistance, and possibly also the hypoxaemia, contribute to the acceleration of breathing. The behaviour of RR, spectral parameters and D2 indicates a specific, functional setting rather than a regulatory impairment in infants with BPD.
Patzak
A
A
Johannes-Müller-Institut für Physiologie, Universitätsklinikum Charité, Humboldt-Universität zu Berlin, Berlin, Germany.
Schlüter
B
B
Mrowka
R
R
Unbehaun
A
A
Gerhardt
D
D
Persson
P B
PB
Barschdorff
D
D
Trowitzsch
E
E
D001997:Bronchopulmonary Dysplasia / Q000503:physiopathology; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010313:Partial Pressure; D010507:Periodicity; D012016:Reference Values; D012143:Respiratory Physiological Phenomena; D012867:Skin / Q000378:metabolism; D012890:Sleep / Q000502:physiology*
D002245:Carbon Dioxide; D010100:Oxygen