Document Detail

Re-evaluation of acid-base prediction rules in patients with chronic respiratory acidosis.
MedLine Citation:
PMID:  14530822     Owner:  NLM     Status:  MEDLINE    
RATIONALE: The prediction rules for the evaluation of the acid-base status in patients with chronic respiratory acidosis, derived primarily from an experimental canine model, suggest that complete compensation should not occur. This appears to contradict frequent observations of normal or near-normal pH levels in patients with chronic hypercapnia. METHODS: Linear regression analysis was used to estimate the relationships between arterial pH, bicarbonate and partial pressure of carbon dioxide (PCO2) from 18 separate arterial blood gas measurements in 18 clinically stable outpatients with chronic hypercapnic respiratory failure from chronic obstructive lung disease, and without clinical conditions or medications likely to cause a primary metabolic alkalosis. RESULTS: The PCO2 ranged from 45 mmHg to 77 mmHg, and pH ranged from 7.37 to 7.44. In only three of the arterial blood gas measurements were the pH values lower than 7.38. From the regression equations derived from these measurements, the pH decreased by 0.014 for each 10 mmHg increase in the PCO2, and the bicarbonate level increased by 5.1 mmol/L. These values are quite different from a decrease in pH of 0.03 and an increase in bicarbonate of 3.5 mmol/L predicted using the rules derived from the canine model. CONCLUSIONS: In patients with chronic stable hypercapnia, acid-base compensatory mechanisms appear to be more effective than would be predicted using the classic rules.
Tereza Martinu; Dick Menzies; Sandra Dial
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Canadian respiratory journal : journal of the Canadian Thoracic Society     Volume:  10     ISSN:  1198-2241     ISO Abbreviation:  Can. Respir. J.     Publication Date:  2003 Sep 
Date Detail:
Created Date:  2003-10-07     Completed Date:  2004-02-13     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9433332     Medline TA:  Can Respir J     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  311-5     Citation Subset:  IM    
Respiratory Epidemiology Unit, Montreal Chest Institute, McGill University, Montreal, Quebec, Canada.
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MeSH Terms
Acid-Base Imbalance / physiopathology*
Acidosis, Respiratory / etiology,  physiopathology*
Adaptation, Physiological / physiology*
Blood Gas Analysis
Carbon Dioxide / physiology
Chronic Disease
Cystic Fibrosis / complications,  physiopathology*
Hydrogen-Ion Concentration
Hypercapnia / etiology,  physiopathology*
Middle Aged
Partial Pressure
Predictive Value of Tests
Pulmonary Disease, Chronic Obstructive / complications,  physiopathology*
Reg. No./Substance:
0/Bicarbonates; 0/Protons; 124-38-9/Carbon Dioxide
Comment In:
Can Respir J. 2003 Sep;10(6):301-3   [PMID:  14530819 ]

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

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