Flow dynamics in pediatric rigid bronchoscopes using computer‐aided design modeling software

Abstract

NA Laryngoscope, 126:1940-1945, 2016.

Predictors of complicated airway foreign body extraction

“…12 Computational fluid dynamics have shown that flow of vital gases within pediatric rigid bronchoscopes is highly turbulent and directed toward the tracheal wall rather than the distal airway, which also may contribute to hypoxemia during rigid bronchoscopy. 13 The limitations of this study include the retrospective data collection and reliance on accurate coding. We did not capture all patients with FBA because there was at least one case well known to our service that required extracorporeal membrane oxygenation and that was not included by our review method.…”

“…Hypoxemia is the most commonly observed adverse event during rigid bronchoscopy, and its causes include over manipulation of surgical instruments in the airway, obstruction of the airway by the foreign body, and secondary inflammation . Computational fluid dynamics have shown that flow of vital gases within pediatric rigid bronchoscopes is highly turbulent and directed toward the tracheal wall rather than the distal airway, which also may contribute to hypoxemia during rigid bronchoscopy …”

Effect of Heliox on Respiratory Outcomes during Rigid Bronchoscopy in Term Lambs

“…3,7 We recently demonstrated highly turbulent flow in the Doesel-Huzly Pediatric Bronchoscope (Karl Storz) as compared with a similar-sized outer-diameter endotracheal tube in a CAD model. 8 One of the limitations of that study was the use of Poiseuille law to calculate resistance, which assumes laminar flow in a system that is known to have turbulent airflow. The current study provides an in vivo model to consider turbulent airflow.…”

“…The laminar and turbulent flow characteristics were calculated with the time-averaged Navier-Stokes equation as previously described. 8…”

“…We found that nearly all sizes of bronchoscopes in this study demonstrated reduced volume flow, higher resistance, and increased turbulence than similar outer-diameter endotracheal tubes. 8 Clinically, this correlates with greater difficulty to adequately ventilate and oxygenate with a rigid bronchoscope, leading us to question the suitability of the device for positive pressure ventilation. Corroborating in vivo studies regarding the use of the ventilating rigid bronchoscope as an airway device are lacking.…”