During the expiratory phase of ventilation, the exhaled gas exits the ETT and is measured proximally at the flow sensor. Where a leak is present, the exhaled tidal volume (VTE) is significantly less than the inhaled tidal volume (VTI). In Adaptive Pressure Ventilation (APV) mode, the HAMILTON-G5 must therefore deliver a higher pressure and potentially a larger VTI to compensate for the leak in order to achieve a tidal volume close to the set exhaled volume target (VTarget).
APV is a volume-targeted, pressure-controlled mode of ventilation. Adjustments in pressure are made in response to the median of the last five exhaled tidal volumes and its relationship to the tidal volume target setting. For this reason, use of APV in infants who present with gross airleaks should be reconsidered (i.e. where VLeak is greater than half of the set VTarget, identified as patients with exhaled tidal volumes ≤ 50% of the inspired tidal volume).
If a tube exchange is clinically acceptable, you may consider replacing the existing tube with a larger ETT. This would increase the likelihood of success in APV, as it facilitates a response more consistent with targeting the exhaled tidal volume. If exchanging the tube is not an option, a traditional pressure-controlled strategy should be considered.
Relevant device(s): HAMILTON-G5
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