Measurements Obtained From Esophageal Balloon Catheters Are Affected by the Esophageal Balloon Filling Volume in Children With ARDS

Abstract

Background: Esophageal balloon inflation volume may affect the accuracy of transpulmo-nary pressure estimates in adults, but the effect is unknown in pediatrics. Using a combination bench and human study, we sought to determine a range of optimal filling volumes for esophageal balloon catheters and to derive a technique to inflate catheters to yield the most accurate estimates of pleural pressure.

Methods: In the laboratory study, we evaluated 4 pediatric and adult esophageal balloon catheters, a liquid-filled catheter, and a micro-tip catheter, both with and without a model esophagus. We compared the measured esophageal pressure for each type of catheter within a pressurized chamber. Esophageal balloon catheters were also tested by manipulating the esophageal balloon inflation volume, and we attempted to derive a filling-volume technique that would assure accuracy. We then tested the feasibility of this technique in 5 mechanically ventilated pediatric subjects with ARDS.

Results: In the laboratory study, smaller inflation volumes underestimated the chamber pressure at higher chamber pressures, and larger inflation volumes overestimated the chamber pressure at lower chamber pressures. Using an optimal filling-volume technique resulted in a mean total error that ranged from -0.53 to -0.10 cm H2O. The optimal filling-volume values for the pediatric catheters were 0.2-0.6 mL, and 0.4-0.8 mL for the adult catheters. When correctly positioned and calibrated, the micro-tip transducer and liquid-filled catheters were within ± 1 cm H2O of chamber pressure for all ranges of pressure. In the clinical study, high variability in measured esophageal pressure and subsequent transpulmonary pressure during exhalation and during inhalation was observed within the manufacturer's recommended esophageal balloon inflation ranges.

Conclusions: Manufacturer-recommended esophageal balloon inflation ranges do not assure accuracy. Individual titration of esophageal balloon volume may improve accuracy. Better esophageal catheters are needed to provide reliable esophageal pressure measurements in children.

Keywords: adult; artificial; catheters; esophagus; lung; pediatrics; pleura; pressure; respiration; respiratory distress syndrome.

Copyright © 2018 by Daedalus Enterprises.

Figures

Fig. 1.

The experimental chamber consisted of a rigid plastic cylinder that was pressurized to 5 different levels using a pressure generator. Each esophageal catheter was tested both with and without a model esophagus. Inflation of the esophageal balloon catheter was accomplished via a 3-way stop cock and pressure tubing. The experimental chamber and esophageal catheter were connected to a measurement device via pressure tubing.

Fig. 2.

The mean and range (error bars) for total error of the esophageal balloon catheters as a function of esophageal balloon inflation volume, and set chamber pressure (Pchamber 5, 10, 15, 20, or 30 cm H2O) stratified by the presence and absence of a model esophagus, and catheter type.

Fig. 3.

Mean and range (error bars) for esophageal pressure (Pes) and total error of the esophageal balloon catheters as a function of esophageal balloon inflation volume and set chamber pressure are shown for the 6 Fr Pediatric (manufacturer-recommended range 0.5–1.25 mL) and 8 Fr Adult (manufacturer-recommended range 0.5–2.25 mL) CareFusion catheters when a model esophagus is used. The dotted vertical lines show the inflation volume that corresponds with the derived optimal filling volume (the median of 3 tests is shown). Note that the optimal filling volume technique commonly results in no difference between chamber and measured esophageal pressure (total error near 0), but there is a tendency to overestimate Pchamber when using the higher end of the manufacturer-recommended range.

Fig. 4.

Mean total error and precision (95% CI) is shown with Bland-Altman plots when using a model esophagus and an esophageal balloon inflation volume that corresponds with the optimal filling volume for each testing condition. Results are stratified by catheter type.

Fig. 5.

Mean and range (error bars) difference between chamber (Pchamber) and measured esophageal pressure (Pes) is shown for the Camino catheter (micro-tip transducer) and the liquid-filled catheter (8 Fr CORFLO) when the liquid-filled catheter tip is level with the transducer and both 5 cm above and below the transducer, stratified by the presence and absence of a model esophagus.

Fig. 6.

Median and IQR (error bars) for PLexp and PLinsp are shown for subjects in the clinical study as a function of esophageal balloon filling volume, stratified by catheter size. Shaded regions highlight the manufacturer-recommended range, and dotted lines and black outline show the mean and range of the derived minimal filling volumes obtained.