Effects of tidal volume and positive end-expiratory pressure during resuscitation of very premature lambs.
BACKGROUND
Guidelines recommend neonatal resuscitation without controlling tidal volume or positive end-expiratory pressure (PEEP). However, these may improve gas exchange, lung volume and outcome.


OBJECTIVE
To investigate resuscitation of very premature lambs with a Laerdal bag without PEEP versus volume guarantee ventilation with PEEP.


METHODS
Anaesthetized lambs (n=20) delivered at 125 d gestation were randomized to three groups receiving 15 min resuscitation: (1) Laerdal bag and no PEEP; (2) ventilation with a tidal volume of 5 ml/kg and 8 cm H(2)O PEEP; (3) ventilation with 10 ml/kg and 8 cm H(2)O PEEP. They were then all ventilated for 2 h with tidal volumes of 5 or 10 ml/kg, and 8 cm H(2)O PEEP. Ventilation parameters and blood gases were recorded.


RESULTS
Different tidal volumes affected PaCO(2) within minutes, with 10 ml/kg causing severe hypocarbia. PEEP had little effect on PaCO(2). Oxygenation improved significantly with PEEP of 8 cm H(2)O, irrespective of tidal volume.


CONCLUSIONS
Very premature lambs can be resuscitated effectively using volume-guarantee ventilation and PEEP. Tidal volumes affected PaCO(2) within minutes but had little effect on oxygenation. PEEP halved the oxygen requirement compared with no PEEP. Resuscitating premature babies with controlled tidal volumes and PEEP might improve their outcome.
Probyn
Megan E
ME
Department of Physiology, Monash University, Melbourne, VIC 3800, Australia.
Hooper
Stuart B
SB
Dargaville
Peter A
PA
McCallion
Naomi
N
Harding
Richard
R
Morley
Colin J
CJ
D000818:Animals; D000831:Animals, Newborn; D002245:Carbon Dioxide / Q000097:blood; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011175:Positive-Pressure Respiration; D012151:Resuscitation / Q000379:methods*; D012756:Sheep; D013990:Tidal Volume
D002245:Carbon Dioxide; D010100:Oxygen