Validation of Airway Occlusion Pressure as a Method of Assessing Breathing Effort During Noninvasive Ventilation

Abstract

Background:

The airway-occlusion pressure is used to estimate the muscle pressure ( ${\text{P}}_{\text{mus}}$ ) and the occlusion pressure at 100 ms ( ${\text{P}}_{\text{0}\text{.1}}$ ) to assess respiratory drive in patients on mechanical ventilation. However, the validity of these maneuvers during noninvasive ventilation (NIV) has not been evaluated. This study was designed to validate the airway-occlusion pressure and the ${\text{P}}_{\text{0}\text{.1}}$ described for mechanical ventilation during NIV in a bench model.

Methods:

This was a bench observational prospective study carried out during January and February 2024 in the ICU laboratory of the Hospital Británico of Buenos Aires.

Results:

In the non-leakage NIV scenarios with oronasal and total face mask, the NIV–airway-occlusion pressure increased with greater ${\text{P}}_{\text{mus}}$ (P < .001). For a programmed ${\text{P}}_{\text{mus}}$ of 5 cm H₂O, values around 4.5 cm H₂O were recorded for both oronasal and total face masks. At 10 cm H₂O, the values were ∼8 cm H₂O, and at 15 cm H₂O, they were ∼11 cm H₂O. With leaks, this difference worsened as leakage increased and the effort decreased. In the Bland-Altman analysis between mechanical ventilation–airway-occlusion pressure and NIV–airway-occlusion pressure without leakage for oronasal and total face masks, we found a good agreement for the 3 levels of ${\text{P}}_{\text{mus}}$ with both types of masks. With regard to the values of NIV–airway-occlusion pressure with the helmet, Bland-Altman analysis showed a high bias and random error. Multivariate analysis found that NIV–airway-occlusion pressure depends on the type of interface, increased with ${\text{P}}_{\text{mus}}$ , and decreased as leakage increased. The agreement of NIV- ${\text{P}}_{\text{0}\text{.1}}$ was not good across all noninvasive measurements.

Conclusions:

This study constitutes a relevant contribution in the validation of indices to assess ${\text{P}}_{\text{mus}}$ during NIV. In a laboratory setting, the measurement of airway-occlusion pressure in NIV may be used to assess effort estimation in the absence of leakage; however, it will likely be underestimated. ${\text{P}}_{\text{0}\text{.1}}$ proved to be an unreliable method. These findings suggest the feasibility of assessing muscle effort during NIV.