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Pressure variation during ventilator generated nasal intermittent positive pressure ventilation in preterm infants
  1. L S Owen1,2,3,
  2. C J Morley1,3,4,
  3. P G Davis1,3,4
  1. 1Royal Women's Hospital, Melbourne, Australia
  2. 2University of Bristol, Bristol, UK
  3. 3Murdoch Children's Research Institute, Melbourne, Australia
  4. 4University of Melbourne, Melbourne, Australia
  1. Correspondence to Dr Louise S Owen, Royal Women's Hospital, Locked Bag 300, Parkville VIC 3052, Australia; louise.owen{at}


Background Nasal intermittent positive pressure ventilation (NIPPV) is a mode of non-invasive respiratory support. Its mechanisms of action and optimal delivery techniques are unknown.

Aim This observational study aimed to investigate and quantify delivered peak pressures during non-synchronised ventilator-generated NIPPV.

Methods Infants born below 30 weeks gestation receiving ventilator-generated NIPPV delivered via Hudson prongs were recruited. Intraprong pressure, change in tidal volume, respiratory rate, oxygen saturations, inspired oxygen and video images were recorded.

Results Eleven infants (four infants were female) of median (interquartile range; IQR) gestational age 25±3 (25±2 26+/-0) weeks and birth weight 732 (699–895) g, were studied at 24 (19–41) days of age. Six infants, with set peak pressure (peak inflation pressure; PIP) of 20 cm H2O, received a median pressure of 15.9 (IQR 13.6–17.9) cm H2O. 37% of inflations were delivered at least 5 cm H2O below set PIP. 12.7% of inflations were delivered above set PIP. Five infants with set PIP of 25 cm H2O received a median PIP of 17.2 (IQR 15.0–18.3) cm H2O. 83% of inflations were delivered at least 5 cm H2O below set PIP, with 6.1% delivered higher than set PIP. The difference in delivered PIP between the groups was 1.3 cm H2O. PIP was highest and most variable when the infant was moving. Delivered PIP did not vary whether it coincided with spontaneous inspiration or expiration.

Conclusion During ventilator-generated non-synchronised NIPPV delivered PIP was variable and frequently lower than set PIP. Delivered PIP was occasionally greater than set PIP.

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  • Funding This work was funded by an Australian National Health and Medical Research Program grant no 384100. LSO is part funded by a Royal Women's Hospital postgraduate research scholarship.

  • Competing interests None.

  • Patient consent Obtained from the parents.

  • Ethics approval This study was approved by the Research and Ethics Committees of the Royal Women's Hospital, Melbourne, Victoria, Australia: project number 07/03.

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