Presented at the Neonatal Society 2010 Autumn Meeting.
Murthy V1, Fox GF2, Campbell ME2, Milner A1, Greenough A1
1 School of Medicine, Division of Asthma, Allergy and Lung Biology, King’s College London, UK
2 Evelina Children’s Hospital Neonatal Unit, St Thomas’ Hospital, London, UK
Background: The current internationally agreed consensus (1) for preterm resuscitation is to use peak inspiratory pressures of 20-25cm H2O with inspiratory times of 2-3 sec for the first 5 inflation breaths. The aim of the prolonged inspiratory time is to establish a functional residual capacity (FRC) and deliver appropriate tidal volumes (VT). There have been a number of studies on manikins to assess the adequacy of face mask resuscitation and the degree to which the guidelines are followed but there is little information on the efficacy of resuscitation of preterm infants in clinical practice. Our aim was to assess the efficacy of face mask resuscitation of prematurely born infants using respiratory function monitoring equipment.
Methods: This study used a Respiratory function monitor (RFM), which has an integrated dual flow, pressure and carbon dioxide sensor. The RFM was connected to a computer laptop with recording and analysis software. Air flow, airway pressure and tidal volume traces were recorded during the resuscitation of infants born before 34 weeks gestation and later analysed. Clinicians involved in preterm resuscitation were all trained and certified in newborn life support (Resuscitation council, UK). Parental consent was obtained for analysis of the data and the study was approved by the Outer North London ethics committee.
Patients: Infants requiring intubation at birth were excluded. Thirty preterm infants with a median gestational age of 30+4 (23+1 – 34) weeks and a median birth weight of 1445 (596-2370) grams were studied. Sixty three % of the infants were delivered by Caesarean section and 76% of the mothers had received antenatal steroids. The median Apgar scores were 6 and 9 at 1 and 5 min of age respectively. Fifty seven % of the resuscitations were performed by a junior trainee.
Results: Traces from 150 inflation breaths were assessed. Twenty two inflations associated with infants’ own breaths and traces of 4 inflation breaths of poor quality were excluded. Of the remaining 124 inflation breaths, the median peak inspiratory pressure was 23.5 (11.5-37.5) cm of H2O, median inspiratory time was 1 (0.25-3.4) second and the median face mask leak was 60.75% (5.1-100). The median tidal volume delivered was 2.1 (0 – 19.8) ml/kg,) There was a significant positive correlation between inflation pressure and tidal volume (p<0.01). Face mask leak and tidal volume were negatively correlated (p<0.01). There was no correlation between inspiratory time and tidal volume.
Conclusion: During the resuscitation of prematurely born infants, tidal volumes sufficient to produce effective ventilation (4.4ml/kg i.e. twice the anatomical dead space) are rarely achieved. Neonatal clinical staff rarely maintain initial inflation for more than 1.5 seconds. The lack of correlation between inspiratory time and delivered tidal volume does not support the claim that prolonged inflation improves tidal volume.
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1. The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: neonatal resuscitation. Pediatrics. 2006.