Pressure- versus volume-limited sustained inflations at resuscitation of premature newborn lambs
1 The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Victoria 3168, Australia
2 Neonatal Research, Murdoch Children’s Research Institute, Melbourne, Australia
3 Neonatal Research, The Royal Women’s Hospital, Melbourne, Australia
4 Neonatology, The Royal Children’s Hospital, Melbourne, Australia
5 Department of Paediatrics, University of Melbourne, Melbourne, Australia
6 Centre for Neonatal Research and Education, School of Paediatrics and Child Health, University of Western Australia, Perth, Australia
7 School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia
8 CAS Medical Systems Inc, Branford, CT, USA
9 Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, USA
10 Cincinnati Children’s Hospital Medical Centre, Cincinnati, Ohio, USA
11 Neonatal Clinical Care Unit, Women and Newborn Health Service, King Edward Memorial Hospital, Subiaco 6008, Western Australia, Australia
BMC Pediatrics 2014, 14:43 doi:10.1186/1471-2431-14-43Published: 15 February 2014
Sustained inflations (SI) are advocated for the rapid establishment of FRC after birth in preterm and term infants requiring resuscitation. However, the most appropriate way to deliver a SI is poorly understood. We investigated whether a volume-limited SI improved the establishment of FRC and ventilation homogeneity and reduced lung inflammation/injury compared to a pressure-limited SI.
131 d gestation lambs were resuscitated with either: i) pressure-limited SI (PressSI: 0-40 cmH2O over 5 s, maintained until 20 s); or ii) volume-limited SI (VolSI: 0-15 mL/kg over 5 s, maintained until 20 s). Following the SI, all lambs were ventilated using volume-controlled ventilation (7 mL/kg tidal volume) for 15 min. Lung mechanics, regional ventilation distribution (electrical impedance tomography), cerebral tissue oxygenation index (near infrared spectroscopy), arterial pressures and blood gas values were recorded regularly. Pressure-volume curves were performed in-situ post-mortem and early markers of lung injury were assessed.
Compared to a pressure-limited SI, a volume-limited SI had increased pressure variability but reduced volume variability. Each SI strategy achieved similar end-inflation lung volumes and regional ventilation homogeneity. Volume-limited SI increased heart-rate and arterial pressure faster than pressure-limited SI lambs, but no differences were observed after 30 s. Volume-limited SI had increased arterial-alveolar oxygen difference due to higher FiO2 at 15 min (p = 0.01 and p = 0.02 respectively). No other inter-group differences in arterial or cerebral oxygenation, blood pressures or early markers of lung injury were evident.
With the exception of inferior oxygenation, a sustained inflation targeting delivery to preterm lambs of 15 mL/kg volume by 5 s did not influence physiological variables or early markers of lung inflammation and injury at 15 min compared to a standard pressure-limited sustained inflation.