The effect of the volumetric flow rate and endotracheal tube diameter on the pressure distribution in human airways

Selvaggio, André Zamith; Lisboa, Sérgio Machado; Vianna, Sávio S.V.

doi:10.1016/j.medengphy.2021.05.003

Cited by 3 publications

(2 citation statements)

References 23 publications

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“…Despite several studies having focused on the harmful effects of pendelluft, its leading causative factors are not fully understood. To investigate these factors, a computer simulation study is suitable because it can handle a three-dimensional model and visualize the airflow inside the tracheobronchial tree under arbitrary boundary conditions imitating various respiratory status, such as the intensity of mechanical support and inspiratory effort [25][26][27][28][29][30].…”

Section: Plos Onementioning

confidence: 99%

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Endotracheal tube, by the venturi effect, reduces the efficacy of increasing inlet pressure in improving pendelluft

Takahashi,

Toyama,

Ejima

et al. 2023

PLoS ONE

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In mechanically ventilated severe acute respiratory distress syndrome patients, spontaneous inspiratory effort generates more negative pressure in the dorsal lung than in the ventral lung. The airflow caused by this pressure difference is called pendelluft, which is a possible mechanisms of patient self-inflicted lung injury. This study aimed to use computer simulation to understand how the endotracheal tube and insufficient ventilatory support contribute to pendelluft. We established two models. In the invasive model, an endotracheal tube was connected to the tracheobronchial tree with 34 outlets grouped into six locations: the right and left upper, lower, and middle lobes. In the non-invasive model, the upper airway, including the glottis, was connected to the tracheobronchial tree. To recreate the inspiratory effort of acute respiratory distress syndrome patients, the lower lobe pressure was set at -13 cmH2O, while the upper and middle lobe pressure was set at -6.4 cmH2O. The inlet pressure was set from 10 to 30 cmH2O to recreate ventilatory support. Using the finite volume method, the total flow rates through each model and toward each lobe were calculated. The invasive model had half the total flow rate of the non-invasive model (1.92 L/s versus 3.73 L/s under 10 cmH2O, respectively). More pendelluft (gas flow into the model from the outlets) was observed in the invasive model than in the non-invasive model. The inlet pressure increase from 10 to 30 cmH2O decreased pendelluft by 11% and 29% in the invasive and non-invasive models, respectively. In the invasive model, a faster jet flowed from the tip of the endotracheal tube toward the lower lobes, consequently entraining gas from the upper and middle lobes. Increasing ventilatory support intensifies the jet from the endotracheal tube, causing a venturi effect at the bifurcation in the tracheobronchial tree. Clinically acceptable ventilatory support cannot completely prevent pendelluft.

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Section: Plos Onementioning

confidence: 99%

“…Recently, some computational gas flow analyses simulating the connection between a patient's airway and an ETT were performed. These studies showed that the gas flow in the patient's airway was affected by the faster jet flow through the ETT [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%