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Airway Occlusion Pressure and P0.1 to Estimate Inspiratory Effort and Respiratory Drive in Ventilated Children
Michelle W Rudolph1, Maaike Sietses1, Alette A Koopman1
1Department of Paediatrics, Division of Paediatric Critical Care Medicine, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Insights
Airway occlusion pressure (Δ Pocc) measurements are consistent regardless of proximal or distal placement, correlating highly with esophageal pressure (Δ Pes). This supports noninvasive quantification of inspiratory effort in ventilated children.
Area of Science:
- Critical Care Medicine
- Pediatric Respiratory Physiology
- Mechanical Ventilation
Background:
- Accurate assessment of inspiratory effort is crucial in mechanically ventilated patients, especially children.
- Airway occlusion pressure (P0.1 and Δ Pocc) are common measures of respiratory drive.
- Understanding the agreement between proximal and distal measurements and correlation with esophageal pressure is essential for clinical application.
Purpose of the Study:
- To compare proximal and distal measurements of airway occlusion pressure at 100 ms (P0.1) and occlusion pressure (Δ Pocc).
- To evaluate the correlation between Δ Pocc and peak-to-trough esophageal pressure (Δ Pes).
- To assess the impact of measurement site on P0.1 and Δ Pocc accuracy.
Main Methods:
- Secondary analysis of a prospectively collected physiology dataset from a medical-surgical pediatric intensive care unit (PICU).
- Included children (<18 years) requiring mechanical ventilation >24 hours with spontaneous breathing.
- Analyzed data from expiratory hold maneuvers, measuring proximal and distal Δ Pocc and P0.1, and correlating with Δ Pes.
Main Results:
- Proximal and distal Δ Pocc measurements showed excellent agreement (r > 0.99) and were not significantly affected by measurement site.
- P0.1 measurements also showed good correlation between proximal and distal sites (r > 0.80), though with wider agreement limits.
- Δ Pocc demonstrated a high correlation with Δ Pes (r = 0.92), supporting its use as a noninvasive measure of inspiratory effort.
Conclusions:
- Measurement site does not significantly affect Δ Pocc, making it a reliable indicator of inspiratory effort.
- P0.1 measurements may be subject to over- or underestimation depending on the site.
- Δ Pocc is a valuable noninvasive tool for quantifying inspiratory effort in ventilated children, correlating well with esophageal pressure.
Objective:
To compare the level of agreement between proximal (near the subject) and distal (inside the ventilator) measured airway occlusion pressure at 100 ms (P0.1) and occlusion pressure (Δ Pocc ), and to study the correlation between Δ Pocc and peak-to-trough esophageal pressure (Δ Pes ).
Design:
Secondary analysis of prospectively collected physiology dataset (2021-2022).
Setting:
Medical-surgical 20-bed PICU.
Patients:
Children younger than 18 years with and without acute lung injury ventilated greater than 24 hours and spontaneously breathing with appropriate triggering of the ventilator.
Interventions:
None.
Measurements And Main Results:
Data from three expiratory hold maneuvers (with a maximum of three breaths during each maneuver) in 74 subjects (118 measurements) with median age 3 months (interquartile range 1-17), and primary respiratory failure due to a pulmonary infection in 41/74 (55.4%) were studied. The median proximal ∆ Pocc was 6.7 cm H 2 O (3.1-10.7) and median P0.1 4.9 cm H 2 O (4.1-6.0) for the first breath from the maneuver; both increased significantly ( p < 0.001) with the subsequent two breaths during the same maneuver. Median distal ∆ Pocc was 6.8 (2.9-10.8) and P0.1 4.6 (3.9-5.6) cm H 2 O; both increased significantly ( p < 0.001) with the two subsequent breaths. Proximal and distal Δ Pocc ( r > 0.99, p < 0.001) and P0.1 ( r > 0.80, p < 0.001) were correlated. Correlation between ventilator displayed and Y-piece measured Δ Pocc ( r > 0.99) and P0.1 ( r = 0.85) was good. Mean ( sd ) difference for Δ Pocc was 0.13 (0.21); levels of agreement were -0.28 and 0.54. For P0.1, mean ( sd ) difference was -0.36 (1.14) and levels of agreement -2.61 and 1.88. There was a high correlation between Δ Pes and ∆ Pocc ( r = 0.92) for the same breath and a good correlation with Δ Pes from the preceding breath ( r = 0.76). There was a poor correlation with the transpulmonary pressure ( r = 0.37).
Conclusions:
Δ Pocc is not affected by measurement site, whereas P0.1 may be overestimated or underestimated. Δ Pocc was highly correlated with the peak-to-trough esophageal pressure, supporting the concept that inspiratory effort can also be quantified noninvasively by measuring Δ Pocc .
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