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Updated: Jun 25, 2026
Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
Published on: February 20, 2017
Work of breathing during SIMV with and without pressure support
D-S Patel1, G F Rafferty, S Lee
1Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College London, London, UK.
Objective:
In a randomised trial, pressure support with synchronised intermittent mandatory ventilation (SIMV) compared to SIMV alone was associated with a significant reduction in supplementary oxygen duration. The hypothesis that the addition of pressure support to SIMV compared to SIMV alone would reduce the work of breathing was examined.
Design:
Prospective study.
Setting:
Perinatal service.
Patients:
20 infants, with a mean gestational age of 31 weeks, being weaned from mechanical ventilation were studied.
Interventions:
1 h periods of SIMV and SIMV with pressure support at 50% of the difference between the peak inflating pressure and positive end expiratory pressures.
Main Outcome Measures:
The work of breathing was assessed by measurement of the transdiaphragmatic pressure time product (PTPdi).
Results:
The mean PTPdi on SIMV plus pressure support was 112 cm H(2)Oxs/min, approximately 20% lower than that on SIMV alone (141 cm H(2)Oxs/min) (p<0.001).
Conclusion:
The addition of pressure support to SIMV reduces the work of breathing in infants being weaned from the ventilator.
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