Document Detail

Positive end-expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgery.
MedLine Citation:
PMID:  16879466     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Morbidly obese patients have an increased risk for peri-operative lung complications and develop a decrease in functional residual capacity (FRC). Electric impedance tomography (EIT) can be used for continuous, fast-response measurement of lung volume changes. This method was used to optimize positive end-expiratory pressure (PEEP) to maintain FRC. METHODS: Fifteen patients with a body mass index of 49 +/- 8 kg/m(2) were studied during anaesthesia for laparoscopic gastric bypass surgery. Before induction, 16 electrodes were placed around the thorax to monitor ventilation-induced impedance changes. Calibration of the electric impedance tomograph against lung volume changes was made by increasing the tidal volume in steps of 200 ml. PEEP was titrated stepwise to maintain a horizontal baseline of the EIT curve, corresponding to a stable FRC. Absolute FRC was measured with a nitrogen wash-out/wash-in technique. Cardiac output was measured with an oesophageal Doppler method. Volume expanders, 1 +/- 0.5 l, were given to prevent PEEP-induced haemodynamic impairment. RESULTS: Impedance changes closely followed tidal volume changes (R(2) > 0.95). The optimal PEEP level was 15 +/- 1 cmH(2)O, and FRC at this PEEP level was 1706 +/- 447 ml before and 2210 +/- 540 ml after surgery (P < 0.01). The cardiac index increased significantly from 2.6 +/- 0.5 before to 3.1 +/- 0.8 l/min/m(2) after surgery, and the alveolar dead space decreased. P(a)O2/F(i)O2, shunt and compliance remained unchanged. CONCLUSION: EIT enables rapid assessment of lung volume changes in morbidly obese patients, and optimization of PEEP. High PEEP levels need to be used to maintain a normal FRC and to minimize shunt. Volume loading prevents circulatory depression in spite of a high PEEP level.
K Erlandsson; H Odenstedt; S Lundin; O Stenqvist
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Acta anaesthesiologica Scandinavica     Volume:  50     ISSN:  0001-5172     ISO Abbreviation:  Acta Anaesthesiol Scand     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-08-01     Completed Date:  2006-12-28     Revised Date:  2007-09-06    
Medline Journal Info:
Nlm Unique ID:  0370270     Medline TA:  Acta Anaesthesiol Scand     Country:  England    
Other Details:
Languages:  eng     Pagination:  833-9     Citation Subset:  IM    
Department of Anaesthesia and Intensive Care, Sahlgrenska University Hospital, 41345 Göteborg, Sweden.
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MeSH Terms
Anesthesia, General*
Cardiac Output
Electric Impedance
Functional Residual Capacity
Gastric Bypass*
Lung Compliance
Lung Volume Measurements*
Middle Aged
Obesity, Morbid / physiopathology,  surgery*
Positive-Pressure Respiration* / methods
Pulmonary Gas Exchange
Comment In:
Acta Anaesthesiol Scand. 2007 Jul;51(6):783-4   [PMID:  17488311 ]

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

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