Effects of Fiberoptic Bronchoscopy on Mechanical Ventilation Pressures in ICU Patients.
CCCF ePoster library. Lemay F. Oct 3, 2017; 198099; 52
Dr. Francois Lemay
Dr. Francois Lemay
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Effects of Fiberoptic Bronchoscopy on Mechanical Ventilation Pressures in ICU Patients.

Lemay, François1,2; Lefebvre, Jean-Claude1,2; Camiré, Éric1,2; Bibeau, Virginie1,2; Delage, Antoine1,3; Lellouche, François1,3; Chassé, Michaël4,5.

1Département d’anesthésiologie et de soins intensifs, Université Laval, Québec, Canada; 2CHU de Québec-Université Laval, Québec, Canada; 3Institut universitaire de cardiologie et de pneumologie de Québec, Québec, Canada 4Carrefour de l’innovation et de l’Évaluation en Santé, CHUM Research Center, Montréal, Canada. 5Department of Medicine, Montreal University, Montréal, Canada.


The presence of a bronchoscope through the endotracheal tube (ETT) increases peak inspiratory airway pressures. This is thought to be caused by an increase in airway resistance1-3. This may reduce minute-ventilation (MV) as ventilation stops being delivered once the ventilator inspiratory pressure limit is reached. Increasing inspiratory pressure limit during fiberoptic bronchoscopy (FOB) is a strategy used to help maintain MV. However, it is unclear if such strategy results in gas trapping and increased transpulmonary pressures. In the clinical setting, plateau pressures (Pplat) are commonly used to estimate transpulmonary pressures. Based on bench testing data, increasing inspiratory pressure limit preserve the MV with limited impact on Pplat in most circumstances4,5. Whether increasing inspiratory pressure limit result in increased Pplat remains to be assessed in the clinical setting.

The aim of this study was to evaluate the impact of FOB on Pplat in patients ventilated in volume-controlled mode. We hypothesized that increasing inspiratory pressure limit during FOB would not significantly affect Pplat.

We conducted a prospective cohort study of mechanically ventilated patients in the ICU of a tertiary center teaching hospital of both medical and surgical patients (CHU de Québec - Université Laval / Hôtel-Dieu de Québec). The study was approved by the local Research Ethic Board. The inclusion criteria were age ≥ 18 years and mechanically ventilated in a volume-controlled mode through an endotracheal or tracheotomy tube. The exclusion criterias were prior inclusion in the study, refusal by the treating physician, unavailability of the research team and Pplat ≥ 30 cm H2O before FOB. As standardized in our unit, the inspiratory pressure limit was increased up to 80 cmH2O during FOB. No other intervention was made. The primary outcome was variation of Pplat from baseline during FOB. We stratified by ETT size (≤7.5 or ≥ 8.0) as ETT tube size was found to affect MV and Pplat in our physiological bench study.To detect a minimally clinically significant difference of 3 cm H2O from baseline Pplat, and a difference of 5 cm H2O between ETT groups, a total of 36 patients were enrolled (18 in each ETT group). We assumed a standard deviation of 5 cmH2O around Pplat, a power of 80% and an alpha level of 0.05.The secondary outcomes were variations in peak airway pressure and PEEP, desaturations and clinical adverse events. All analysis will be conducted using SAS 9.4.

34 patients have been included in the study as of April 2017. We expect to complete the study by May 2017. Results of our analysis will be presented.

Our study questions the optimal ventilator settings to safely perform FOB in critically ill mechanically ventilated patients. It will provide evidence on whether Pplat increases or not when inspiratory pressure limit is increased. If Pplat increases, this would justify further investigation of its clinical consequences. It could also introduce the importance to monitor Pplat during FOB. If Pplat does not increase, this would support the hypothesis of increased peak airway pressures induced mainly by increased airway resistance. This would support the practice to increase inspiratory pressure limit as a safe and simple measure to optimize MV during FOB.

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