Infants with viral bronchiolitis demonstrate two distinct patterns of nocturnal oxyhaemoglobin desaturation

AimThis study aimed to demonstrate that viral bronchiolitis is associated with intermittent oxygen saturation of haemoglobin (SpO(2)) drops (3%) and low basal SpO(2) between episodes of haemoglobin desaturation. MethodsInfants with bronchiolitis underwent pulse oximetry during the first night following hospital admission and a subgroup of them underwent repeat oximetry before hospital discharge. Oximetry was also performed in infants with partial upper airway obstruction (UAO) and without lung disease and in control participants without UAO or lung disease. ResultsWe enrolled 53 infants: 21 with bronchiolitis, 11 with UAO and 21 healthy controls. Participants with bronchiolitis had lower basal SpO(2) (median 93.7% [10th-90th percentiles: 91.1-96.8]) than the subjects with UAO (96.9% [95.3-98.1]; p<0.01) or the controls (98.7% [96.9-99.3]; p<0.01). The bronchiolitis group was not different from the UAO group regarding the desaturation index (23.3 episodes/hour [10.3-46.6] and 15.5 episodes/hour [5.4-36.4], respectively; p=0.08), but differed significantly from the controls (3.1 episodes/hour [0.3-5.5]; p<0.01). The basal SpO(2) and desaturation index improved in 10 subjects with bronchiolitis who had follow-up oximetry before discharge, but these indices remained abnormal when compared to values in the control group. ConclusionBronchiolitis was characterised by low nocturnal basal SpO(2) and intermittent SpO(2) drops