title: Thoracic electrical impedance and fluid balance during aortic surgery.
abstract: Indices of fluid balance were evaluated during and after aortic surgery in 16 consecutive patients. Thoracic electrical impedance (TI), heart rate (HR), central venous (CVP), pulmonary artery mean (PAMP), pulmonary wedge (PWP) and mean arterial (MAP) pressure as well as fourteen arterial and venous blood gas variables were followed. Consistent with a reduction of T1 by 4.2 (-5.2 to 9.2) Ohm (median and range) during the operation, fluid balance was in excess of 1.8 (-0.1 to 3.3) 1 when evaporation was not taken into account, and it remained elevated by 1.3 (0.0 to 5.4) 1 on the first postoperative morning. The HR, MAP and PWP remained stable, while CVP and PAMP decreased by 6 (-2 to 13) and 6 (-1 to 22) mmHg, respectively. Of the determined variables only TI revealed a meaningful correlation to fluid balance (rho = -0.41; P < 0.01). Haemoglobin concentrations increased in proportion to the administered packed erythrocytes, while arterial oxygen saturation, pH and base excess decreased in proportion to the excess fluid. The results indicate that while central venous and pulmonary artery mean pressures gave the impression of a volume deficit, the positive fluid balance was mirrored by thoracic electrical impedance, and that even a minor increase of fluid balance may affect pulmonary function in patients subjected to aortic surgery.
authors.affiliation: Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: F
authors.initials: F
authors.lastname: Jónsson
authors.forename: P
authors.initials: P
authors.lastname: Madsen
authors.forename: L G
authors.initials: LG
authors.lastname: Jørgensen
authors.forename: M
authors.initials: M
authors.lastname: Lunding
authors.forename: N H
authors.initials: NH
authors.lastname: Secher
mesh_terms: D000368:Aged; D001018:Aortic Diseases / Q000601:surgery*; D001639:Bicarbonates / Q000097:blood; D001794:Blood Pressure; D002496:Central Venous Pressure; D017097:Electric Impedance; D017707:Erythrocyte Transfusion; D005260:Female; D006339:Heart Rate; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011651:Pulmonary Artery; D011669:Pulmonary Wedge Pressure; D013909:Thorax / Q000502:physiology*; D014882:Water-Electrolyte Balance
chemical_list: D001639:Bicarbonates; D006454:Hemoglobins; D010100:Oxygen