Document Detail

Increase of oxygen consumption during a progressive decrease of ventilatory support is lower in patients failing the trial in comparison with those who succeed.
MedLine Citation:
PMID:  20613464     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The aim of this study was to test the hypothesis that, during weaning from mechanical ventilation, when the pressure support level is reduced, oxygen consumption increases more in patients unable to sustain the decrease in ventilatory assistance (weaning failure).
METHODS: Patients judged eligible for weaning were enrolled. Starting from 20 cm H2O, pressure support was decreased in 4-cm H2O steps, lasting 10 min each, until 0 cm H2O; this level was kept for 1 h. The average oxygen consumption from the last 3 min of each step, along with other ventilatory variables, was measured by indirect calorimetry (M-CAiOVX "metabolic module," Engstrom Carestation; GE Healthcare, Madison, WI) and recorded. Patients were defined as belonging to the failure group if, at any moment, they developed signs of respiratory distress according to standard criteria, or to the success group otherwise.
RESULTS: Twenty-eight patients were studied. In most patients, the minimum oxygen consumption was not recorded at the highest pressure support applied. Sixteen patients were able to complete the weaning trial successfully, whereas 12 failed it; the success group had a minimum oxygen consumption lower than failure group (mean +/- SD: 174 +/- 44 vs. 215 +/- 53 ml/min, P < 0.05). Moreover, although respiratory drive (assessed by P0.1) increased more in the failure group, this group had a lower increase in oxygen consumption, contradicting our hypothesis.
CONCLUSIONS: Patients failing a decremental pressure support trial, in comparison with those who succeed, had an higher baseline oxygen consumption and were not able to increase their oxygen consumption in response to an increased demand.
Giacomo Bellani; Giuseppe Foti; Ester Spagnolli; Manuela Milan; Alberto Zanella; Massimilano Greco; Nicolò Patroniti; Antonio Pesenti
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article    
Journal Detail:
Title:  Anesthesiology     Volume:  113     ISSN:  1528-1175     ISO Abbreviation:  Anesthesiology     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-07-26     Completed Date:  2010-08-31     Revised Date:  2011-06-13    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  378-85     Citation Subset:  AIM; IM    
Department of Experimental Medicine, University of Milan-Bicocca, Monza, Italy.
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MeSH Terms
Aged, 80 and over
Middle Aged
Oxygen Consumption / physiology*
Pulmonary Wedge Pressure / physiology
Respiration, Artificial / methods
Respiratory Distress Syndrome, Adult / diagnosis*,  physiopathology
Respiratory Function Tests / methods
Respiratory Insufficiency / diagnosis*,  physiopathology
Time Factors
Treatment Outcome
Ventilator Weaning / methods*
Comment In:
Anesthesiology. 2010 Aug;113(2):273-5   [PMID:  20613463 ]
Anesthesiology. 2011 May;114(5):1243; author reply 1244   [PMID:  21521971 ]
Anesthesiology. 2011 May;114(5):1243-4; author reply 1244   [PMID:  21521970 ]

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