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Title: Optimisation of neonatal ventilation
Author: Patel, Deena
Awarding Body: King's College London (University of London)
Current Institution: King's College London (University of London)
Date of Award: 2014
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Background: Infants born prematurely or at term may unfortunately suffer morbidity from ventilator related complications. New ventilation techniques have been developed aimed at reducing that morbidity, but have yet to be fully evaluated. Aim: To optimise the delivery of new techniques using physiological outcome measures. Methods: A series of studies were undertaken. The objectives were: • In prematurely born infants with acute respiratory distress, to determine the optimal level of volume targeted ventilation. • In term and prematurely born infants, to assess the effect on work of breathing of the addition of pressure support (PSV) to synchronised intermittent mandatory ventilation (SIMV) during weaning and then compare the efficacy of PSV to assist control (ACV) in a randomised trial. • To perform in vitro and in vivo assessments of proportional assist ventilation (PAV). • The physiological outcome measures were the transdiaphragmatic pressure time product (PTPdi), respiratory muscle strength, thoracoabdominal asynchrony, tension time index of the diaphragm and assessment of asynchronous events. Results: A volume target of 4ml/kg in comparison to 6ml/kg or no volume targeting resulted in a higher PTPdi (p <0.001). In infants weaning from the ventilator, the PTPdi was 20% lower (p <0.001) during SIMV with PSV in comparison to SIMV alone. No significant difference in the duration of weaning was demonstrated between PSV and ACV. The in vitro PAV study highlighted abnormalities of airway pressure waveform and higher than excepted airway pressures during both elastic and resistive unloading. Conclusions: Low levels of volume targeting even within the ‘physiological’ range significantly increased the work of breathing. A triggered mode supporting all the infant breaths was superior to when a limited number of breaths were supported. When similar inflation times were used, triggered modes supporting all breaths were equally efficacious. Unloading levels affect the efficacy of PAV; these may be determined by using the ventilator calculated respiratory mechanics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available