title: Measurement of pleural pressure with oesophageal catheter-tip micromanometer in anaesthetized humans.
abstract: In spontaneously breathing anaesthetized subjects, we studied a new technique for the measurement of changes in pleural pressure. Seven ASA physical status I patients undergoing general anaesthesia (enflurane 1-2 MAC, nitrous oxide 50%, and oxygen) for minor orthopaedic surgery were studied in the supine position. Changes in oesophageal pressure (delta Pes) were measured by means of a catheter-tip pressure transducer. This micromanometer was positioned according to an occlusion test where delta Pes were compared with the changes in airway opening pressure (delta Pao). Optimizing the signal/noise ratio, we observed a linear relationship between delta Pes and delta Pao. In each patient, the delta Pes/delta Pao relationship was highly reproducible. Using the linear regression analysis to characterize the delta Pes/delta Pao relationship, we have developed a different approach for the positioning of oesophageal catheter. After statistical analysis of the observed delta Pes/delta Pao relationship, a "calibration" factor can be used in order to correct the observed slope of the delta Pes/delta Pao relationship to its theoretical value. We conclude that an oesophageal catheter-tip micromanometer can be used in anaesthetized supine patients to measure changes in pleural pressure.
authors.affiliation: Department of Anaesthesia, Hôtel-Dieu de Montréal, University of Montreal, Quebec.
authors.forename: D A
authors.initials: DA
authors.lastname: Chartrand
authors.forename: C
authors.initials: C
authors.lastname: Jodoin
authors.forename: J
authors.initials: J
authors.lastname: Couture
mesh_terms: D000328:Adult; D000771:Anesthesia, Intravenous; D002404:Catheterization / Q000295:instrumentation*; D004947:Esophagus / Q000502:physiology*; D006801:Humans; D008365:Manometry / Q000295:instrumentation*; D008904:Miniaturization / Q000295:instrumentation; D009991:Oscillometry / Q000295:instrumentation; D010100:Oxygen / Q000502:physiology; D010994:Pleura / Q000502:physiology*; D011312:Pressure; D012044:Regression Analysis; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology*; D014160:Transducers, Pressure
chemical_list: D010100:Oxygen