Document Detail

The effect of hypo-, normo-, and hypercapnia induced by mechanical ventilation on intrapulmonary shunt.
MedLine Citation:
PMID:  7800919     Owner:  NLM     Status:  MEDLINE    
The effects of hypo-, normo- and hypercapnia on the variations in arterial oxygenation and their indices in critical patients with acute respiratory failure (ARF) receiving mechanical ventilation are studied. It is a prospective and randomized study carried out in multidisciplinary ICU. Fifteen ARF patients, intubated and mechanically ventilated, were studied within the first 48 h of evolution. Three stages were delimited: I) 30 min after the beginning of anaesthesia; II) 30 min after adding 30 cm of dead space (VD); III) 30 min after replacing the previous VD with VD of 60 cm. Ventilation parameters and FiO2 were kept stable. Stage I was characterized by respiratory alkalosis and stage II by normal acid-base balance with an increase in PaO2 (p < 0.01) and a decrease in intrapulmonary shunt (Qsp/Qt) (p < 0.001); the indices alveolar to arterial oxygen tension gradient [P(A-a)O2], respiratory index (R.I.) and estimated shunt (Est Shunt) also decreased significantly, whereas arterial to alveolar oxygen tension ratio (PaO2/PAO2) and arterial oxygen tension to inspired oxygen fraction ration (PaO2/FiO2) increased significantly. In stage III there was pure hypercapnic acidosis, with decreases in PAO2 (p < 0.001), P(A-a)O2 (p < 0.01) and R.I. (p < 0.05), while PaO2, Qsp/Qt, Est Shunt, PaO2/PAO2 and PaO2/FiO2 remained stable with respect to the previous situation. The observed PaO2 differs (p < 0.05) from the expected PaO2 in stage III. It is suggested that local or regional modifications of pulmonary perfusion are responsible for the observed variations. The P(A-a)O2 and R.I. indices do not make it possible to differentiate the causes of arterial hypoxemia in the presence of hypercapnia.
J H Boix; F Alvarez; M Tejeda; E Peydro; D Olivares; A Arnau
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  Revista española de fisiología     Volume:  50     ISSN:  0034-9402     ISO Abbreviation:  Rev. Esp. Fisiol.     Publication Date:  1994 Jun 
Date Detail:
Created Date:  1995-01-20     Completed Date:  1995-01-20     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0404475     Medline TA:  Rev Esp Fisiol     Country:  SPAIN    
Other Details:
Languages:  eng     Pagination:  89-95     Citation Subset:  IM; S    
UCI, Hospital, Castellón, Spain.
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MeSH Terms
Acute Disease
Alkalosis / blood,  etiology,  physiopathology*
Carbon Dioxide / blood*
Hypercapnia / etiology,  physiopathology*
Hypocapnia / etiology,  physiopathology*
Middle Aged
Oxygen / blood
Partial Pressure
Prospective Studies
Respiration, Artificial / adverse effects*
Respiratory Dead Space
Respiratory Function Tests
Respiratory Insufficiency / blood,  physiopathology*
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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

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