Relationship between computerized wheeze detection and lung function parameters in young infants.

OBJECTIVE: Computerized respiratory sound analysis (CORSA) has been validated in the assessment of wheeze in infants, but it is unknown whether automatically detected wheeze is associated with impaired lung function. This study investigated the relationship between wheeze detection and conventional lung function testing (LFT) parameters.

METHODS: CORSA was performed using the PulmoTrack® monitor in 110 infants, of median (interquartile range) postmenstrual age 50 (46-56) weeks and median body weight 4,810 (3,980-5,900) g, recovering from neonatal intensive care. In the same session, LFT was performed, including tidal breathing measurements, occlusion tests, body plethysmography, forced expiratory flow by rapid thoracoabdominal compression, sulfur hexafluoride (SF6 ) multiple breath washout (MBW), and capillary blood gas analysis. Infants were classified as wheezers or non-wheezers using predefined cut-off values for the duration of inspiratory and expiratory wheeze.

RESULTS: Wheezing was detected in 72 (65%) infants, with 43 (39%) having inspiratory and 53 (48%) having expiratory wheezing. Endotracheal mechanical ventilation in the neonatal period for > 24 hr was associated with inspiratory wheeze (P = 0.009). Airway resistance was increased in both inspiratory (P = 0.02) and expiratory (P = 0.004) wheezers and correlated with the duration of expiratory wheeze (r = 0.394, P < 0.001). Expiratory wheezers showed a significant increase in respiratory resistance (P = 0.001), time constant (0.012), and functional residual capacity using SF6 MBW (P = 0.019). There was no association between wheezing and forced expiratory flow or blood gases.

CONCLUSION: CORSA can help identify neonates and young infants with subclinical airway obstruction and may prove useful in the follow-up of high-risk infants.