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Original Research |

The Effects of Flexible Bronchoscopy on Mechanical Ventilation in a Pediatric Lung Model

Danny Hsia, MD*; Robert M. DiBlasi, RRT-NPS; Peter Richardson, PhD; David Crotwell, RRT-NPS; Jason Debley, MD, MPH; Edward Carter, MD, FCCP
Author and Funding Information

*From the Department of Pediatrics (Drs. Hsia, Richardson, Debley, and Carter), University of Washington School of Medicine, Seattle, WA; and the Department of Respiratory Care (Mr. DiBlasi and Mr. Crotwell), Center for Developmental Therapeutics, Seattle Children's Hospital Research Institute, Seattle, WA.

Correspondence to: Danny Hsia, MD, Bay Area Pediatric Pulmonary Medical Corporation, Children's Hospital & Research Center at Oakland, 747 52nd St, Suite 5409, Oakland, CA 94609; e-mail: dhsia@mail.cho.org

*In PC ventilation, the set PIP-generated Vt of 6 to 7 mL/kg. In the VC mode, the Vt was set at 7 mL/kg and generated PIPs of 15 cm H2O in the infant (4 kg) model and approximately 20 cm H2O in the other models.

IMV = intermittent mandatory ventilation.

*Only the 15 kg size model and 2.8 mm bronchoscope/4.5 mm ETT combination were used. The ventilator settings were as follows: PC mode: IMV, 20 breaths/min; PIP, 20 cm H2O; PEEP, 5 cm H2O; and inspiratory time, 0.6 s; VC mode: IMV, 20 breaths/min; Vt, 135 mL; PEEP, 5 cm H2O; and inspiratory time, 0.6 s.

*Combinations are expressed as the bronchoscope outer diameter (in millimeters)/ETT inner diameter (in millimeters).

*Combinations are expressed as bronchoscope outer diameter (in millimeters)/ETT inner diameter (in millimeters).

†Baseline PIP was 20 cm H2O for all except the 4-kg model in which it was 15 cm H2O.

For editorial comment see page 2

This article was presented in part at the 2007 International Conference of the American Thoracic Society, San Francisco, CA, May 18–23, 2007.

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).


For editorial comment see page 2

For editorial comment see page 2

This article was presented in part at the 2007 International Conference of the American Thoracic Society, San Francisco, CA, May 18–23, 2007.

This article was presented in part at the 2007 International Conference of the American Thoracic Society, San Francisco, CA, May 18–23, 2007.

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).


Chest. 2009;135(1):33-40. doi:10.1378/chest.08-1000
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Published online

Background:  Flexible bronchoscopy performed through endotracheal tubes (ETTs) in children receiving mechanical ventilation can significantly impact ventilation, but the magnitude of this impact has not been established. We used a lung model to simulate mechanical ventilation in a range of child sizes in order to determine how the insertion of pediatric flexible bronchoscopes into ETTs alters ventilatory parameters, especially tidal volume (Vt) and peak inspiratory pressure (PIP), in both healthy and diseased lungs.

Methods:  We simulated five child sizes based on weight, and evaluated 22 bronchoscope/ETT combinations, first in pressure control (PC) ventilation mode and then in volume control (VC) ventilation mode. The combinations ranged from the 2.2-mm (bronchoscope outer diameter)/3.0-mm (ETT inner diameter) to 5.0-mm bronchoscope/8.0-mm ETT. The primary outcome measures were decrease in Vt after bronchoscope insertion during PC ventilation and increase in PIP during VC ventilation.

Results:  In the PC ventilator mode, Vt decreased by > 50% with nine of the combinations, while during VC ventilation, PIP increased by ≥ 20 cm H2O with seven combinations. The 2.2-mm bronchoscope/3.0-mm ETT, 2.8-mm bronchoscope/5.0-mm ETT, and 3.6-mm bronchoscope/5.0-mm ETT combinations severely impaired ventilation, while the 3.6-mm bronchoscope/4.5-mm ETT, 5.0-mm bronchoscope/6.5-mm ETT, and 5.0-mm bronchoscope/7.0-mm ETT combinations were incompatible with adequate ventilation.

Conclusions:  The insertion of bronchoscopes into ETTs can lead to clinically relevant decreases in Vt when in the PC ventilator mode and large increases in PIP during VC ventilation. The minimum bronchoscope/ETT diameter difference required to maintain adequate ventilation increases with child size.

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