Esophageal Balloon Lab Report

Background: Clinical experience within our hospital has brought into question the accuracy of measurements obtained from pediatric sized esophageal balloons in small children when the balloon is inflated. We have studied spontaneously breathing children both on and off ventilators that have suspiciously high esophageal pressures when the balloon is inflated. The purpose of this experiment was to explore what affect a simulated infant esophagus would have on the accuracy of the measurements obtained from an esophageal balloon when balloon inflation amount is manipulated.
Method: A 1 liter syringe was connected to an experimental chamber in order to create dynamic, positive and negative pressures within a range of -40cmH20 to +40cmH20. Within the chamber, a 6fr and an 8fr esophageal balloon (Carefusion, YorbaLinda, CA) were inserted into separate model infant esophagi constructed from a 6mm Penrose drain. Each catheter was inflated to two levels, below recommended inflation values at 0.2ml, and to recommended inflation values (0.5ml for the 6fr catheter, and 0.7ml for the 8fr catheter). Pressure measurements obtained from the esophageal catheter at each condition were
Pressures measured from the 6fr esophageal catheter during every condition and the 8fr catheter only during negative pressure with 0.7ml inflation were statistically different from the chamber pressure (p < 0.001). The 8fr catheter was not statistically different during negative pressure with 0.2ml inflation (p = 0.153), positive pressure with 0.2ml inflation (p=0.183), and positive pressure with 0.7ml inflation (p =0.568). Further, Cohen’s effect size value suggests large differences between the esophageal catheter pressure and actual chamber pressure when using the 6fr catheter during negative pressure with 0.2ml inflation (d = -0.91) and 0.5ml inflation (d =