Detailed measurements of oesophageal pressure during mechanical ventilation with an advanced high-resolution manometry catheter

Per Persson,Rebecca Ahlstrand,Alex De Leon,Magni Gudmundsson,Stefan Lundin

doi:10.1186/s13054-019-2484-8

Per Persson, Rebecca Ahlstrand + Show 3 more

Open Access

https://doi.org/10.1186/s13054-019-2484-8

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Abstract

BackgroundOesophageal pressure (PES) is used for calculation of lung and chest wall mechanics and transpulmonary pressure during mechanical ventilation. Measurements performed with a balloon catheter are suggested as a basis for setting the ventilator; however, measurements are affected by several factors. High-resolution manometry (HRM) simultaneously measures pressures at every centimetre in the whole oesophagus and thereby provides extended information about oesophageal pressure. The aim of the present study was to evaluate the factors affecting oesophageal pressure using HRM.MethodsOesophageal pressure was measured using a high-resolution manometry catheter in 20 mechanically ventilated patients (15 in the ICU and 5 in the OR). Different PEEP levels and different sizes of tidal volume were applied while pressures were measured continuously. In 10 patients, oesophageal pressure was also measured using a conventional balloon catheter for comparison. A retrospective analysis of oesophageal pressure measured with HRM in supine and sitting positions in 17 awake spontaneously breathing patients is also included.ResultsHRM showed large variations in end-expiratory PES (PESEE) and tidal changes in PES (ΔPES) along the oesophagus. Mean intra-individual difference between the minimum and maximum end-expiratory oesophageal pressure (PESEE at baseline PEEP) and tidal variations in oesophageal pressure (ΔPES at tidal volume 6 ml/kg) recorded by HRM in the different sections of the oesophagus was 23.7 (7.9) cmH2O and 7.6 (3.9) cmH2O respectively. Oesophageal pressures were affected by tidal volume, level of PEEP, part of the oesophagus included and patient positioning. HRM identified simultaneous increases and decreases in PES within a majority of individual patients. Compared to sitting position, supine position increased PESEE (mean difference 12.3 cmH2O), pressure variation within individual patients and cardiac artefacts. The pressure measured with a balloon catheter did not correspond to the average pressure measured with HRM within the same part of the oesophagus.ConclusionsThe intra-individual variability in PESEE and ΔPES is substantial, and as a result, the balloon on the conventional catheter is affected by many different pressures along its length. Oesophageal pressures are not only affected by lung and chest wall mechanics but are a complex product of many factors, which is not obvious during conventional measurements. For correct calculations of transpulmonary pressure, factors influencing oesophageal pressures need to be known. HRM, which is available at many hospitals, can be used to increase the knowledge concerning these factors.Trial registrationClinicalTrials.gov, NCT02901158

Highlights

Oesophageal pressure (PES) is used for calculation of lung and chest wall mechanics and transpulmonary pressure during mechanical ventilation
Measurements with High-resolution manometry (HRM) revealed a variable effect on oesophageal pressures when PEEP was increased, and often both increases and decreases in end-expiratory oesophageal pressures were seen within the same patient (Fig. 1 and Additional file 1: Figures S2, S3, S4, S5)
The surprisingly large variation in pressure along the oesophagus, the increase in pressure in supine position and the unpredictable change in pressure as a response to increased PEEP or tidal inflation indicate a substantial influence on oesophageal pressures from the external factors such as the weight of the mediastinum and the cardiovascular system

Summary

Introduction

Oesophageal pressure (PES) is used for calculation of lung and chest wall mechanics and transpulmonary pressure during mechanical ventilation. Apart from the discussion of how to use the absolute or tidal changes in oesophageal pressures in calculations of transpulmonary pressure [8,9,10], there are several factors that influence the measurements. Both absolute end-expiratory and tidal variations in oesophageal pressures are affected by the positioning of the balloon [11, 12], filling volumes of the balloon [12, 13] and type of catheter used [14]. A better understanding of oesophageal pressures and influencing factors would be of great importance since measured values could have a profound effect on ventilator settings in the ICU and during general anaesthesia

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