Validation of esophageal pressure occlusion test after paralysis

Abstract

Measurements of respiratory mechanics are frequently made in ventilated infants and children. Esophageal pressure measurements (Pes) using a balloon on a catheter have been used to partition the respiratory mechanics into lung and chest wall components. Appropriate positioning of this balloon is crucial to obtain accurate estimates of pleural pressure. Traditionally, in spontaneously breathing subjects the balloon position is assessed with an occlusion test. In ventilated subjects, it is not always possible to perform an occlusion test prior to paralysis, and even if such a test is performed it may be relevant under conditions of positive pressure ventilation. By occluding the airway opening and applying gentle pressure to the abdomen or rib cage, positive swings in pressure can be measured by both Pes and airway opening pressure (Pao). We compared traditional occlusion tests measured in 16 spontaneously breathing puppies to the positive pressure occlusion test performed after paralysis. In 2 pups we were unable to obtain a reasonable traditional occlusion test (> 15% difference between Pes and Pao) but we obtained 10 traditional occlusion tests in each of the remaining 14 pups (2.1-14 kg). In 11 of these animals delta Pes was within 10% of delta Pao. This compared well to positive pressure occlusion test using abdominal pressure performed after analysis, where delta Pes was within 10% of delta Pao in 10 animals. In 9 of these pups occlusion tests were also performed by applying pressure on the rib cage, where delta Pes was within 10% of delta Pao in 6 animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Matching positive end-expiratory pressure to intra-abdominal pressure prevents end-expiratory lung volume decline in a pig model of intra-abdominal hypertension*

“…The catheter was first inserted into the stomach. Thereafter, the catheter was retracted stepwise until optimal position in the esophagus was confirmed with a positive occlusion test as previously described (24,25). Airway pressure (P AW ) was transduced at the proximal end of the endotracheal tube.…”

Effects of Gestation and Antenatal Steroid on Airway and Tissue Mechanics in Newborn Lambs

“…Esophageal pressure (Pes) was measured using a 5 Fr catheter-tip micromanometer (MTC 5F; Dräger Medical Electronics, The Netherlands). The catheter tip was positioned in the distal third of the esophagus to obtain a smooth respiratory pressure waveform with minimal cardiac artifact, and the position was confirmed with a positive pressure occlusion test (12). Frequency calibration between the flow transducer and each of the pressure transducers was incorporated in the preprocessing of data.…”

Influence of inertance on respiratory mechanics measurements in mechanically ventilated puppies

“…6 A pressure transducer (model 142PC01D, were placed between the tracheal tube and the ventilator to measure airway opening pressure (P AO ) and flow (V . ) respectively.…”

“…6 A minimum of two 20 second data epochs were collected at each ventilation frequency. These epochs contained a number of breaths which were ensemble averaged to obtain a single averaged breath for each epoch.…”