Document Detail

Assessment of ventilation-perfusion mismatching in mechanically ventilated patients.
MedLine Citation:
PMID:  9864016     Owner:  NLM     Status:  MEDLINE    
The multiple inert gas elimination technique (MIGET) is a robust tool to assess both ventilation-perfusion (V'A/Q') distributions and the role of extrapulmonary factors determining arterial oxygenation during spontaneous breathing and in mechanically ventilated patients. Mixed expired gas sampling used in the MIGET is most often obtained from a 10-L mixing box (10L-MB) placed in the expiratory side of the ventilator circuit. Consequently, a considerable increase in the compression volume (Vc) would be expected which, in turn, can give rise to potential errors in the estimation of the effective tidal volume delivered to the patient. The effects of the 10L-MB on the Vc were compared with those produced by a newly designed 1-L, mixing box (IL-MB). At a given peak pressure (Ppeak) within the ventilator circuit, the Vc generated by the 10L-MB was about six-times higher than that produced by the 1L-MB. At a Ppeak =50 cmH2O, the Vc were 377 mL (10L-MB) and 67 mL (1L-MB) (p<0.001). In six patients, the mixed expired partial pressures of the six inert gases simultaneously collected from the two mixing boxes fell on the identity line. V'A/Q' distributions recovered using each of the two mixing boxes were equivalent. With the IL-MB, the effects of different positive end-expiratory pressure levels (0, 6 and 12 cmH2O) on Vc and arterial carbon dioxide tension were negligible. In conclusion, the new 1-L mixing box provides efficient gas mixing and substantially decreases the compression volume. It is, therefore, recommended when studies requiring mixed expired gas are performed in ventilated patients.
M Ferrer; E Zavala; O Díaz; J Roca; P D Wagner; R Rodriguez-Roisin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The European respiratory journal     Volume:  12     ISSN:  0903-1936     ISO Abbreviation:  Eur. Respir. J.     Publication Date:  1998 Nov 
Date Detail:
Created Date:  1999-03-23     Completed Date:  1999-03-23     Revised Date:  2013-05-23    
Medline Journal Info:
Nlm Unique ID:  8803460     Medline TA:  Eur Respir J     Country:  DENMARK    
Other Details:
Languages:  eng     Pagination:  1172-6     Citation Subset:  IM    
Dept de Medicina, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Universitat de Barcelona, Spain.
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MeSH Terms
Carbon Dioxide / blood
Middle Aged
Oxygen / blood
Positive-Pressure Respiration
Respiration, Artificial* / instrumentation,  methods
Tidal Volume
Ventilation-Perfusion Ratio*
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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