Document Detail

An investigation to show the effect of lung fluid on impedance cardiac output in the anaesthetized dog.
MedLine Citation:
PMID:  16051651     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Accumulation of lung fluid in the critically ill patient is believed to attenuate impedance cardiac output (CO(IC)) measurements. However, this phenomenon has never been shown experimentally. METHODS: In eight anaesthetized and ventilated dogs (weight 15-22 kg) a high-precision flow probe was placed on the ascending aorta via a left thoracotomy incision and the direct cardiac output (CO(FP)) was measured. Simultaneous CO(IC) measurements were made using a RheoCardioMonitor (ACMA, Singapore). Lung oedema was induced by intravenous oleic acid 0.1 mg kg(-1). Lung fluid was assessed by the decrease in basal thoracic impedance (Z(b)). Percentage errors between the two methods (CO(IC)-CO(FP)) were calculated and compared as Z(b) decreased at 1 Omega intervals. RESULTS: During the experiment mean Z(b) decreased from 35.9 (sd 5.2) to 27.8 (6.5) Omega (P=0.0037). This occurred over a period of 225 (range 112-338) min and Z(b) decreased by 1 Omega every 51 (22-68) min. The presence of excessive lung fluid was confirmed at post-mortem. Before lung oedema was induced, CO(IC) was 1.5 (0.6) litre min(-1) and the corresponding value of CO(FP) was 1.5 (0.7) litre min(-1) (data from eight dogs). As Z(b) decreased, and lung fluid accumulated, the error between CO(IC) and CO(FP) widened (P<0.0001, anova for repeated measures). Eventually, CO(IC) decreased to 0.7 (0.3) litre min(-1) and the corresponding value of CO(FP) was 1.2 (0.3) litre min(-1) (DeltaZ(b)=5 Omega, data from six dogs). Mean arterial pressure, central venous pressure and systemic vascular resistance were kept constant. CONCLUSION: The presence of lung fluid attenuates CO(IC) measurements with respect to CO(FP).
Z-Y Peng; L A H Critchley; B S P Fok
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-07-28
Journal Detail:
Title:  British journal of anaesthesia     Volume:  95     ISSN:  0007-0912     ISO Abbreviation:  Br J Anaesth     Publication Date:  2005 Oct 
Date Detail:
Created Date:  2005-09-12     Completed Date:  2005-11-15     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0372541     Medline TA:  Br J Anaesth     Country:  England    
Other Details:
Languages:  eng     Pagination:  458-64     Citation Subset:  IM    
Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Shatin.
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MeSH Terms
Aorta / physiopathology
Cardiac Output*
Cardiography, Impedance
Monitoring, Physiologic / methods
Oleic Acid
Pulmonary Edema / chemically induced,  physiopathology*
Reproducibility of Results
Reg. No./Substance:
112-80-1/Oleic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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