Document Detail

Expiratory washout versus optimization of mechanical ventilation during permissive hypercapnia in patients with severe acute respiratory distress syndrome.
MedLine Citation:
PMID:  10390383     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to compare three ventilatory techniques for reducing PaCO2 in patients with severe acute respiratory distress syndrome treated with permissive hypercapnia: (1) expiratory washout alone at a flow of 15 L/min, (2) optimized mechanical ventilation defined as an increase in the respiratory frequency to the maximal rate possible without development of intrinsic positive end- expiratory pressure (PEEP) combined with a reduction of the instrumental dead space, and (3) the combination of both methods. Tidal volume was set according to the pressure-volume curve in order to obtain an inspiratory plateau airway pressure equal to the upper inflection point minus 2 cm H2O after setting the PEEP at 2 cm H2O above the lower inflection point and was kept constant throughout the study. The three modalities were compared at the same inspiratory plateau airway pressure through an adjustment of the extrinsic PEEP. During conventional mechanical ventilation using a respiratory frequency of 18 breaths/min, respiratory acidosis (PaCO2 = 84 +/- 24 mm Hg and pH = 7.21 +/- 0.12) was observed. Expiratory washout and optimized mechanical ventilation (respiratory frequency of 30 +/- 4 breaths/min) had similar effects on CO2 elimination (DeltaPaCO2 = -28 +/- 11% versus -27 +/- 12%). A further decrease in PaCO2 was observed when both methods were combined (DeltaPaCO2 = -46 +/- 7%). Extrinsic PEEP had to be reduced by 5.3 +/- 2.1 cm H2O during expiratory washout and by 7.3 +/- 1.3 cm H2O during the combination of the two modes, whereas it remained unchanged during optimized mechanical ventilation alone. In conclusion, increasing respiratory rate and reducing instrumental dead space during conventional mechanical ventilation is as efficient as expiratory washout to reduce PaCO2 in patients with severe ARDS and permissive hypercapnia. When used in combination, both techniques have additive effects and result in PaCO2 levels close to normal values.
J Richecoeur; Q Lu; S R Vieira; L Puybasset; P Kalfon; P Coriat; J J Rouby
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  160     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1999 Jul 
Date Detail:
Created Date:  1999-08-11     Completed Date:  1999-08-11     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  77-85     Citation Subset:  AIM; IM    
Réanimation Chirurgicale Pierre Viars, Department of Anesthesiology, La Pitié-Salpêtrière Hospital, University of Paris VI, France.
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MeSH Terms
Acidosis, Respiratory / physiopathology,  therapy
Carbon Dioxide / blood*
Combined Modality Therapy
Hemodynamics / physiology
Hypercapnia / physiopathology,  therapy*
Lung Volume Measurements
Middle Aged
Positive-Pressure Respiration
Prospective Studies
Pulmonary Diffusing Capacity / physiology
Respiration, Artificial* / instrumentation
Respiratory Dead Space / physiology
Respiratory Distress Syndrome, Adult / physiopathology,  therapy*
Treatment Outcome
Reg. No./Substance:
124-38-9/Carbon Dioxide

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

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