Solid-state esophageal pressure sensor for the estimation of pleural pressure: a bench and first-in-human validation study

Background: 

Advanced respiratory monitoring through the measurement of esophageal pressure (Pes) as a surrogate of pleural pressure helps guiding mechanical ventilation in ICU patients. Pes measurement with an esophageal balloon catheter, the current clinical reference standard, needs complex calibrations and a multitude of factors influence its reliability. Solid-state pressure sensors might be able to overcome these limitations. 

Objectives: 

To evaluate the accuracy of a new solid-state Pes transducer (Pes_solid). We hypothesized that measurements are non-inferior to those obtained with a properly calibrated balloon catheter (Pes_bal).

Methods:

Absolute and relative solid-state sensor Pes measurements were compared to a reference pressure in a 5-day bench setup, and to simultaneously placed balloon catheters in 15 spontaneously breathing healthy volunteers and in 16 mechanically ventilated ICU patients. Bland–Altman analysis was performed using mixed effects modelling with bootstrapping to estimate bias and upper and lower limits of agreement (LoA) and their confidence intervals. 

Results: 

Bench study: Solid-state pressure transducers had a positive bias (P_solid – P_ref) of around 1 cmH₂O for the absolute minimal and maximum pressures, and no bias for pressure swings. Healthy volunteers: the solid-state transducer revealed a bias (i.e._, Pes_solid – Pes_bal) [upper LoA; lower LoA] of 1.59 [8.21; − 5.02], − 2.32 [4.27; − 8.92] and 3.91 [11.04; − 3.23] cmH₂O for end-expiratory, end-inspiratory and ΔPes values, respectively. ICU patients: the solid-state transducer showed a bias (Pes_solid–Pes_bal) [upper LoA; lower LoA] during controlled/assisted ventilation of: − 0.15 [1.41; − 1.72]/− 0.19 [5.23; − 5.62], 0.32 [3.45; − 2.82]/− 0.54 [4.81; − 5.90] and 0.47 [3.90; − 2.96]/0.35 [4.01; − 3.31] cmH₂O for end-expiratory, end-inspiratory and ΔPes values, respectively. LoA were ≤ 2cmH₂O for static measurements on controlled ventilation. 

Conclusions: 

The novel solid-state pressure transducer showed good accuracy on the bench, in healthy volunteers and in ventilated ICU-patients. This could contribute to the implementation of Pes as advanced respiratory monitoring technique. Trial registration: Clinicaltrials.gov identifier: NCT05817968 (patient study). Registered on 18 April 2023.