Obstetrics and Gynaecology - Theses

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    Pulse oximetry during neonatal transition: the POINT studies
    Dawson, Jennifer Anne ( 2009)
    The objectives for the first part of this thesis were to describe changes in oxygen saturation (SpO2) and heart rate (HR) in newly born infants in the delivery room (DR) and to illustrate the changes using centile reference charts. The objective of the second part of the thesis was to investigate whether infants < 29 weeks gestation who receive positive pressure ventilation (PPV), immediately after birth with a T-piece have higher SpO2 measurements at five minutes than infants ventilated with a self inflating bag (SIB). Study Design. A prospective observational study was used to achieve the first objectives. For the second part of the thesis I coordinated a randomised, controlled trial of two devices used for resuscitation of extremely preterm infants in the DR where the primary outcome measure was SpO2. Patients and methods. In all studies a Masimo Radical pulse oximeter (PO) was placed on the infant’s right hand/wrist immediately after birth. PO data (oxygen saturation, HR and signal quality) were downloaded every 2 sec and analysed only when the signal had no alarm messages (low IQ signal, low perfusion, sensor off, ambient light). Results. Observational studies: The dataset to develop the reference range charts included 61,650 data points from 468 infants. Infants had a mean (range) gestational age of 38 (25-42) weeks and birthweight 2970 (625-5135) g. For all 468 infants at one minute the 3rd, 10th, 50th, 90th and 97th centiles were 29%, 39%, 66%, 87% and 92%; at two minutes 34%, 46%, 73%, 91% and 95% and at five minutes 59%, 73%, 89%, 97% and 98%. It took a median of 7.9 (IQR 5.0 to 10) minutes to reach a SpO2 > 90%. SpO2 of preterm infants rose more slowly than that of term infants. At one min the median (IQR) HR was 82 (66 to 138) bpm rising at two min and five min to 151 (112 to 169) bpm and 166 (148 to 176) bpm respectively. In preterm infants, the SpO2 and HR rose more slowly than term infants. Randomised trial: Forty nine infants were randomly allocated to the T-piece and 50 to the SIB. Ten infants did not receive PPV, 4 (8%) in the T-piece group and 6 (12%) in the SIB group and were not included in the analysis. Forty-one infants received PPV with a T-piece and 39 with a SIB. At 5 minutes after birth there was no significant difference between the mean (SD) SpO2 in the T-piece and SIB groups [50 (31)% vs. 53 (25)%, (p=0.73)]. More T-piece infants received oxygen during DR resuscitation (100% vs. 90%, p=0.04). There was no significant difference between the groups in the use of continuous positive airway pressure (CPAP); endotracheal intubation or administration of surfactant in the DR. Fewer of the T-piece group who left the DR on CPAP were intubated in the first 24 hrs after birth. (7% vs. 23%, p=0.05). Conclusion. The centile charts developed in this thesis provide a reference range for SpO2 and HR in the first 10 minutes after birth for preterm and term infants. In the randomised trial there was no significant difference in SpO2 at five minutes after birth in extremely preterm infants given PPV with a T-piece or a SIB.