Document Detail

Effects of extreme lateral posture on hemodynamics and plasma atrial natriuretic peptide levels in critically ill patients.
MedLine Citation:
PMID:  8844229     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To quantify the hemodynamic effects of turning critically ill, mechanically ventilated patients to the extreme left and right lateral postures. DESIGN: Prospective investigation. SETTING: Eight-bed intensive care unit in a university hospital. PATIENTS: Twelve consecutive patients presenting with severe respiratory failure and requiring continuous positive inotropic support. INTERVENTIONS: All patients were mechanically ventilated and placed in a kinetic treatment system. They were positioned in the supine, left dependent, and right dependent postures, resting for 15 min in each position. MEASUREMENTS AND RESULTS: Hemodynamic measurements, assessments of right ventricular function, and determinations of intrathoracic blood volume were performed in three different positions. Concentrations of atrial natriuretic peptide in plasma were quantified. In three patients, the findings were controlled by transesophageal echocardiography. Cardiac index [median (range) 5.5 (3.2-8.1) vs 4.3 (3.2-7.5) l/min per m2, p < 0.01], intrathoracic blood volume [1125 (820-1394) vs 1037 (821-1267) ml/m2, p < 0.01], and right ventricular end-diastolic volume [130 (83-159) vs 114 (79-155) ml/m2, p < 0.05] increased significantly in the left dependent position compared to supine. Mean arterial pressure did not change. Atrial natriuretic peptide levels rose from 140 to 203 pg/ml. In the right dependent position, we found a marked decrease in the mean arterial pressure [85 mmHg (supine) to 72 mmHg (right dependent), p < 0.01]. Cardiac index and intrathoracic blood volume were unchanged, but right ventricular end-diastolic volume decreased from 114 to 102 ml/m2 (p < 0.05). Additionally, atrial natriuretic peptide levels decreased significantly (median delta value: 37 pg/ml). In echocardiographic controls we found an increase in right ventricular end-diastolic diameters in the left dependent position and shortened diameters in the right dependent position. CONCLUSIONS: Extreme lateral posture affects the cardiovascular system in critically ill, mechanically ventilated patients: in the left dependent position a "hyperdynamic state" is reinforced, while the right decubitus position impairs right ventricular preload and predisposes to hypotension. Echocardiography and changes in plasma atrial natriuretic peptide values indicate that these findings are due to altered distensibility of the right ventricle caused by regional intrathoracic gravitational changes. We conclude that the duration and the angle of lateral posture should be restricted in hemodynamically unstable patients.
T Bein; C Metz; C Keyl; M Pfeifer; K Taeger
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Intensive care medicine     Volume:  22     ISSN:  0342-4642     ISO Abbreviation:  Intensive Care Med     Publication Date:  1996 Jul 
Date Detail:
Created Date:  1996-12-20     Completed Date:  1996-12-20     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7704851     Medline TA:  Intensive Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  651-5     Citation Subset:  IM    
Department of Anesthesia, University Hospital, University of Regensburg, Germany.
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MeSH Terms
Acute Disease
Atrial Natriuretic Factor / blood*
Critical Illness
Echocardiography, Transesophageal
Middle Aged
Monitoring, Physiologic
Prospective Studies
Respiration, Artificial
Respiratory Insufficiency / blood,  physiopathology*,  ultrasonography
Reg. No./Substance:
85637-73-6/Atrial Natriuretic Factor

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

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