Role of overnight oximetry in assessing the severity of obstructive sleep apnoea in typically developing children: a multicentre study.

BACKGROUND AND OBJECTIVE: Cardiorespiratory polygraphy (CRP) is the predominant technology used to diagnose obstructive sleep apnoea (OSA) in tertiary centres in the UK. Nocturnal pulse oximetry (NPO) is, however, cheaper and more accessible. This study evaluated the ability of NPO indices to predict OSA in typically developing (TD) children. METHODS: Indices from simultaneous NPO and CRP recordings were compared in TD children (aged 1-16 years) referred to evaluate OSA in three tertiary centres. OSA was defined as an obstructive apnoea-hypopnoea index (OAHI) ≥1 event/hour. Receiver operating characteristic curves assessed the diagnostic accuracy of NPO indices including ODI3 (3% Oxygen Desaturation Index, ODI4 (4% Oxygen Desaturation Index), delta 12 s index and minimum oxygen saturation. Two-by-two tables were generated to determine the sensitivities and specificities of whole number cut-off values for predicting OAHIs ≥1, 5 and 10 events/hour. RESULTS: Recordings from 322 TD children, 197 male (61.2%), median age 4.9 years (range 1.1-15.6), were reviewed. OAHI was ≥1/hour in 144 (44.7%), ≥5/hour in 61 (18.9%) and ≥10/hour in 28 (8.7%) cases. ODI3 and ODI4 had the best diagnostic accuracy. ODI3 ≥7/hour and ODI4 ≥4/hour predicted OSA in TD children with sensitivities/specificities of 57.6%/85.4% and 46.2%/91.6%, respectively. ODI3 ≥8/hour was the best predictor of OAHI ≥5/hour (sensitivity 82.0%, specificity 84.3%). CONCLUSION: Raised ODI3 and ODI4 predict OSA in TD children with high specificity but variable sensitivity. NPO may be an alternative to diagnose moderate-severe OSA if access to CRP is limited. Low sensitivities to detect mild OSA mean that confirmatory CRP is needed if NPO is normal.

Longitudinal pilot study of oxygen saturation indices in healthy preterm infants.

BACKGROUND: This study aimed to determine patterns of nocturnal pulse oximetry indices in moderate to late preterm infants, and investigate the relationship between oxygen desaturations, the apnoea hypopnoea index, and both corrected gestational and postnatal age. METHODS: 21 healthy infants born at 32 + 0 - 36 + 6 weeks gestation underwent serial nocturnal pulse oximetry studies and respiratory polygraphy studies until 40 weeks corrected gestational age (CGA). The main outcome measures were number of >3% oxygen desaturations/hour (ODI3), mean oxygen saturations, and number of apnoeas and hypopnoeas/hour. RESULTS: Median ODI3 increased between weeks 1 and 3 from 49.9 to 85.4/hour (p = 0.017). Mean oxygen saturations reached a corresponding nadir of 96.0% in week 3, then increased to 96.8% in week 6 (p = 0.019). Mixed effects modelling demonstrated that ODI3 and mean saturations were influenced by postnatal age but not CGA (p < 0.05). Desaturations frequently occurred without an apnoea or hypopnoea. CONCLUSION: ODI3 rises then falls during the first 8 weeks of life in moderate to late preterm infants, independently of CGA. These interesting preliminary results highlight the importance of further serial data collection to generate age-specific normal ranges, and develop a better understanding of respiratory control in preterm infants. IMPACT: The frequency of >3% oxygen desaturations (ODI3) in healthy moderate to late preterm infants rises then falls after birth, peaking in postnatal week 3. There is a corresponding nadir in mean saturations. There were significant non-linear relationships between ODI3/mean saturations and postnatal age, but not corrected gestational age. The majority of brief oxygen desaturations occurred without an apnoea or hypopnoea. Normal ranges for oxygen saturation indices are not known in this population. These results demonstrate the need for further serial data collection to generate age-specific normal ranges and inform oxygen prescribing guidelines.