Effect of Endotracheal Tube Size, Respiratory System Mechanics, and Ventilator Settings on Driving Pressure

Stavroula Ilia, Patrick D van Schelven, Alette A Koopman, Robert G T Blokpoel, Pauline de Jager, Johannes G M Burgerhof, Dick G Markhorst, Martin C J Kneyber

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Objectives: We sought to investigate factors that affect the difference between the peak inspiratory pressure measured at the Y-piece under dynamic flow conditions and plateau pressure measured under zero-flow conditions (resistive pressure) during pressure controlled ventilation across a range of endotracheal tube sizes, respiratory mechanics, and ventilator settings. Design: In vitro study. Setting: Research laboratory. Patients: None. Interventions: An in vitro bench model of the intubated respiratory system during pressure controlled ventilation was used to obtain the difference between peak inspiratory pressure measured at the Y-piece under dynamic flow conditions and plateau pressure measured under zero-flow conditions across a range of endotracheal tubes sizes (3.0–8.0 mm). Measurements were taken at combinations of pressure above positive end-expiratory pressure (10, 15, and 20 cm H2O), airway resistance (no, low, high), respiratory system compliance (ranging from normal to extremely severe), and inspiratory time at constant positive end-expiratory pressure (5 cm H2O). Multiple regression analysis was used to construct models predicting resistive pressure stratified by endotracheal tube size. Measurements and Main Results: On univariate regression analysis, respiratory system compliance (β –1.5; 95% CI, –1.7 to –1.4; p < 0.001), respiratory system resistance (β 1.7; 95% CI, 1.5–2.0; p < 0.001), pressure above positive end-expiratory pressure (β 1.7; 95% CI, 1.4–2.0; p < 0.001), and inspiratory time (β –0.7; 95% CI, –1.0 to –0.4; p < 0.001) were associated with resistive pressure. Multiple linear regression analysis showed the independent association between increasing respiratory system compliance, increasing airway resistance, increasing pressure above positive end-expiratory pressure, and decreasing inspiratory time and resistive pressure across all endotracheal tube sizes. Inspiratory time was the strongest variable associated with a proportional increase in resistive pressure. The contribution of airway resistance became more prominent with increasing endotracheal tube size. Conclusions: Peak inspiratory pressures measured during pressure controlled ventilation overestimated plateau pressure irrespective of endotracheal tube size, especially with decreased inspiratory time or increased airway resistance.

Original languageEnglish
Pages (from-to)E47-E51
Number of pages5
JournalPediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies
Volume21
Issue number1
Early online date1-Nov-2019
DOIs
Publication statusPublished - Jan-2020

Keywords

  • driving pressure
  • in vitro techniques
  • mechanical ventilation
  • pediatric intensive care unit
  • pressure controlled ventilation
  • resistive pressure
  • ACUTE LUNG INJURY
  • VOLUME
  • CHILDREN
  • METAANALYSIS
  • MORTALITY

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