ObjectiveTo describe the distribution of perfusion index (PI) in asymptomatic newborns at 24 hours of life when screening for critical congenital heart disease (CCHD) using an automated data selection method.DesignThis is a retrospective observational study.SettingNewborn nursery in a California public hospital with ~3500 deliveries annually.MethodsWe developed an automated programme to select the PI values from CCHD screens. Included were term and late preterm infants who were screened for CCHD from November 2013 to January 2014 and from May 2015 to July 2015. PI measurements were downloaded every 2 s from the pulse oximeter and median PI were calculated for each oxygen saturation screen in our cohort.ResultsWe included data from 2768 oxygen saturation screens. Each screen had a median of 29 data points (IQR 17 to 49). The median PI in our study cohort was 1.8 (95% CI 1.8 to 1.9) with IQR 1.2 to 2.7. The median preductal PI was significantly higher than the median postductal (1.9 vs 1.8, p=0.03) although this difference may not be clinically significant.ConclusionUsing an automated data selection method, the median PI in asymptomatic newborns at 24 hours of life is 1.8 with a narrow IQR of 1.2 to 2.7. This automated data selection method may improve accuracy and precision compared with manual data collection method. Further studies are needed to establish external validity of this automated data selection method and its clinical application for CCHD screening.

ObjectiveTo describe haematocrit at birth in preterm infants who received ≥60 s of delayed cord clamping (DCC).DesignRetrospective observational study.SettingA California public hospital with an American Academy of Pediatrics level 4 neonatal intensive care unit, with 3500–4000 deliveries annually.Participants467 preterm infants born at <35 weeks’ gestational age (GA) between January 2013 and December 2018.Primary and secondary outcome measuresHaematocrit reference ranges for 0–4 hours after birth and paired haematocrit differences between 0–4 and 4–24 hours.MethodsHaematocrits were obtained when clinically indicated and collected from arterial, venous and capillary sources. Haematocrits obtained after packed red blood cell transfusions were excluded. We summarised the first available haematocrit between 0 and 4 hours by GA strata. We used mixed-effects linear regression to describe the associations between haematocrit and predictor variables including GA, male sex and hours after an infant’s birth. We also compared paired haematocrits at 0–4 and 4–24 hours after birth.ResultsThe median GA of the 467 included infants was 33.3 weeks, birth weight was 1910 g and DCC duration was 60 s. The mean (95% CI) first haematocrit at 0–4 hours was 46.6 (45.0% to 48.1%), 51.2 (49.6% to 52.8%), 50.6 (49.1% to 52.1%), 54.3 (52.8% to 55.8%) and 55.6 (54.6% to 56.6%) for infants 23–29, 30–31, 32, 33 and 34 weeks’ GA strata, respectively. The subanalysis of 174 infants with paired haematocrits at 0–4 and 4–24 hours showed that for each additional hour after birth, the mean (95% CI) haematocrit increased by 0.2 (0.1% to 0.3%), 0.2 (0.1% to 0.4%) and 0.1 (0.0% to 0.2%) for infants in 23–29, 30–31 and 32 weeks’ GA strata, respectively. The subanalysis showed no change between the paired haematocrits in the 33 and 34 weeks’ GA strata.ConclusionsOur study describes haematocrit in preterm infants who received ≥60 s DCC as standard of care. Haematocrit during the first 0–4 hours in our study is higher than the previously described reference ranges prior to DCC becoming routine clinical practice. The paired second haematocrit at 4–24 hours is higher than haematocrit at 0–4 hours.