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Automated Versus Manual Occlusion Pressure at 100 ms With Hamilton C6 Using the Software Version 1.2.3: From Bedside
Flora Delamaire1,2, Jérémy Caldonazzo3,4, Arnaud Gacouin1,2,5
1Médecine Intensive - Réanimation, CHU de Rennes, Rennes, France.
Objectives:
Occlusion pressure at 100 ms after the start of inspiratory effort (P0.1) is a marker of respiratory drive and a predictor of weaning outcomes in mechanically ventilated patients. Some ventilators, like the Hamilton C6 (Hamilton Medical AG, Bonaduz, Switzerland), estimate P0.1 automatically (P0.1vent) without performing an actual airway occlusion, potentially leading to inaccuracies.
Setting:
This prospective clinical and bench study aimed to assess the accuracy of P0.1vent compared with the manual occlusion method (P0.1occ) during spontaneous breathing trials (SBT) and following a reventilation period with varying ventilator settings.
Design And Patients:
The clinical part of the study included patients undergoing SBT on Hamilton C6 (software version 1.2.3) with zero pressure support (PS) and zero end-expiratory pressure (PEEP) and reventilation (PS +8 cm H2O, PEEP +5 cm H2O). P0.1vent and P0.1occ were collected every 15 minutes. Bench part evaluated the P0.1vent and P0.1occ of the Hamilton C6 (software version 1.2.3) connected to a lung simulator (ASL 5000) creating different breathing efforts across different lung mechanics and varying PS and PEEP levels.
Measurement And Main Results:
In patients, P0.1vent values were significantly higher than P0.1occ (median, 11.0 vs. 1.0 cm H2O; p < 0.001), with a mean bias of 8.5 cm H2O. Similar overestimations were observed during the reventilation period (6.0 vs. 1.0 cm H2O; mean difference, 6.5 cm H2O; p < 0.001). Bench results confirmed the variable accuracy of P0.1vent found in the clinical part of the study, with biases ranging from nearly perfect (0.2 cm H2O) under high PS to 2.3 cm H2O under low PS.
Conclusions:
Automatic P0.1 estimation by the Hamilton C6 (software version 1.2.3) is inaccurate during SBTs. Manual occlusion remains essential for reliable P0.1 assessment at the bedside.
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