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Effect of sustained inflation duration; resuscitation of near-term asphyxiated lambs
  1. Claus Klingenberg1,2,
  2. Kristina S Sobotka3,
  3. Tracey Ong3,
  4. Beth J Allison3,
  5. Georg M Schmölzer3,5,6,
  6. Timothy J M Moss3,4,
  7. Graeme R Polglase3,
  8. Jennifer A Dawson6,
  9. Peter G Davis6,
  10. Stuart B Hooper3,4
  1. 1Department of Paediatrics, University Hospital of North Norway, Tromsø, Norway
  2. 2Paediatric Research Group, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
  3. 3The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia
  4. 4Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia
  5. 5Department of Pediatrics, Medical University, Graz, Austria
  6. 6Neonatal Research, Royal Women's Hospital, Melbourne, Australia
  1. Correspondence to Claus Klingenberg, Department of Paediatrics, University Hospital of North Norway, N-9038 Tromsø, Norway; claus.klingenberg{at}unn.no

Abstract

Objective The 2010 ILCOR neonatal resuscitation guidelines do not specify appropriate inflation times for the initial lung inflations in apnoeic newborn infants. The authors compared three ventilation strategies immediately after delivery in asphyxiated newborn lambs.

Design Experimental animal study.

Setting Facility for animal research.

Subjects Eighteen near-term lambs (weight 3.5–3.9 kg) delivered by caesarean section.

Interventions Asphyxia was induced by occluding the umbilical cord and delaying ventilation onset (10–11 min) until mean carotid blood pressure (CBP) was ≤22 mm Hg. Animals were divided into three groups (n=6) and ventilation started with: (1) inflation times of 0.5 s at a ventilation rate 60/min, (2) five 3 s inflations or (3) a single 30 s inflation. Subsequent ventilation used inflations at 0.5 s at 60/min for all groups.

Main outcome measures Times to reach a heart rate (HR) of 120 bpm and a mean CBP of 40 mm Hg. Secondary outcome was change in lung compliance.

Results Median time to reach HR 120 bpm and mean CBP 40 mm Hg was significantly shorter in the single 30 s inflation group (8 s and 74 s) versus the 5×3 s inflation group (38 s and 466 s) and the conventional ventilation group (64 s and 264 s). Lung compliance was significantly better in the single 30 s inflation group.

Conclusion A single sustained inflation of 30 s immediately after birth improved speed of circulatory recovery and lung compliance in near-term asphyxiated lambs. This approach for neonatal resuscitation merits further investigation.

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Footnotes

  • Both CK and KS contributed equally to this study.

  • Funding PGD and SBH hold an Australian National Health and Medical Research Council Program Grant No. 384100. PGD is a recipient of an NHMRC Practitioner Fellowship. JAD and GMS are past recipients of a RWH Postgraduate Scholarship. GRP and SBH are NH&MRC Research Fellows and the authors gratefully acknowledge the Victorian Government's Operational Infrastructure Support Program. JAD is recipient of a National Health and Medical Research Council Post Doctoral Fellowship.

  • Competing interests None.

  • Ethics approval All experimental procedures were approved by the relevant Monash University Animal Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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