title: Liquid- and air-filled catheters without balloon as an alternative to the air-filled balloon catheter for measurement of esophageal pressure.
abstract: BACKGROUND
  Measuring esophageal pressure (Pes) using an air-filled balloon catheter (BC) is the common approach to estimate pleural pressure and related parameters. However, Pes is not routinely measured in mechanically ventilated patients, partly due to technical and practical limitations and difficulties. This study aimed at comparing the conventional BC with two alternative methods for Pes measurement, liquid-filled and air-filled catheters without balloon (LFC and AFC), during mechanical ventilation with and without spontaneous breathing activity. Seven female juvenile pigs (32-42 kg) were anesthetized, orotracheally intubated, and a bundle of an AFC, LFC, and BC was inserted in the esophagus. Controlled and assisted mechanical ventilation were applied with positive end-expiratory pressures of 5 and 15 cmH2O, and driving pressures of 10 and 20 cmH2O, in supine and lateral decubitus.
  
  
  RESULTS
  Cardiogenic noise in BC tracings was much larger (up to 25% of total power of Pes signal) than in AFC and LFC (<3%). Lung and chest wall elastance, pressure-time product, inspiratory work of breathing, inspiratory change and end-expiratory value of transpulmonary pressure were estimated. The three catheters allowed detecting similar changes in these parameters between different ventilation settings. However, a non-negligible and significant bias between estimates from BC and those from AFC and LFC was observed in several instances.
  
  
  CONCLUSIONS
  In anesthetized and mechanically ventilated pigs, the three catheters are equivalent when the aim is to detect changes in Pes and related parameters between different conditions, but possibly not when the absolute value of the estimated parameters is of paramount importance. Due to a better signal-to-noise ratio, and considering its practical advantages in terms of easier calibration and simpler acquisition setup, LFC may prove interesting for clinical use.
authors.affiliation: Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany; Department of Electronic Engineering and Postgraduate Program of Electrical Engineering, Federal University of Minas Gerais, Pampulha, Belo Horizonte, Brazil.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Beda
authors.affiliation: Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Güldner
authors.affiliation: Laboratory of Respiration Physiology, Carlos Chagas Filho Biophysics Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Biomedical Engineering Program, Alberto Luis Coimbra Program of Post-Graduation and Research in Engineering, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Alysson R
authors.initials: AR
authors.lastname: Carvalho
authors.affiliation: Laboratory of Respiration Physiology, Carlos Chagas Filho Biophysics Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Walter Araujo
authors.initials: WA
authors.lastname: Zin
authors.affiliation: Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany; Department of Electronic Engineering and Postgraduate Program of Electrical Engineering, Federal University of Minas Gerais, Pampulha, Belo Horizonte, Brazil.
authors.forename: Nadja C
authors.initials: NC
authors.lastname: Carvalho
authors.affiliation: Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Huhle
authors.affiliation: Biomedical Engineering Program, Alberto Luis Coimbra Program of Post-Graduation and Research in Engineering, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Antonio
authors.initials: A
authors.lastname: Giannella-Neto
authors.affiliation: Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany.
authors.forename: Thea
authors.initials: T
authors.lastname: Koch
authors.affiliation: Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany.
authors.forename: Marcelo Gama
authors.initials: MG
authors.lastname: de Abreu
mesh_terms: D000388:Air; D000818:Animals; D002404:Catheterization / Q000295:instrumentation* / Q000379:methods; D004947:Esophagus / Q000502:physiology*; D005260:Female; D006801:Humans; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D010994:Pleura / Q000502:physiology*; D011312:Pressure; D012121:Respiration, Artificial; D015656:Respiratory Mechanics; D059629:Signal-To-Noise Ratio; D013552:Swine / Q000502:physiology*