title: Ultrasound evaluation of piglet diaphragm function before and after fatigue.
abstract: Clinically, a noninvasive measure of diaphragm function is needed. The purpose of this study is to determine whether ultrasonography can be used to 1) quantify diaphragm function and 2) identify fatigue in a piglet model. Five piglets were anesthetized with pentobarbital sodium and halothane and studied during the following conditions: 1) baseline (spontaneous breathing); 2) baseline + CO2 [inhaled CO2 to increase arterial PCO2 to 50-60 Torr (6.6-8 kPa)]; 3) fatigue + CO2 (fatigue induced with 30 min of phrenic nerve pacing); and 4) recovery + CO2 (recovery after 1 h of mechanical ventilation). Ultrasound measurements of the posterior diaphragm were made (inspiratory mean velocity) in the transverse plane. Images were obtained from the midline, just inferior to the xiphoid process, and perpendicular to the abdomen. M-mode measures were made of the right posterior hemidiaphragm in the plane just lateral to the inferior vena cava. Abdominal and esophageal pressures were measured and transdiaphragmatic pressure (Pdi) was calculated during spontaneous (Sp) and paced (Pace) breaths. Arterial blood gases were also measured. Pdi(Sp) and Pdi(Pace) during baseline + CO2 were 8 +/- 0.7 and 49 +/- 11 cmH2O, respectively, and decreased to 6 +/- 1.0 and 27 +/- 7 cmH2O, respectively, during fatigue + CO2. Mean inspiratory velocity also decreased from 13 +/- 2 to 8 +/- 1 cm/s during these conditions. All variables returned to baseline during recovery + CO2. Ultrasonography can be used to quantify diaphragm function and identify piglet diaphragm fatigue.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Kocis
authors.forename: P J
authors.initials: PJ
authors.lastname: Radell
authors.forename: W I
authors.initials: WI
authors.lastname: Sternberger
authors.forename: J E
authors.initials: JE
authors.lastname: Benson
authors.forename: R J
authors.initials: RJ
authors.lastname: Traystman
authors.forename: D G
authors.initials: DG
authors.lastname: Nichols
mesh_terms: D000009:Abdominal Muscles / Q000503:physiopathology; D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D003964:Diaphragm / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D015656:Respiratory Mechanics / Q000502:physiology; D013552:Swine; D014463:Ultrasonography
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen