Chest
Skeletal Muscle Energetics, Acid-Base Equilibrium and Lactate Metabolism in Patients with Severe Hypercapnia and Hypoxemia
Section snippets
Patients
Ten COPD patients (nine men and one woman) who ranged in age from 52 to 75 yr (mean, 62 ± 3 yr SEM) were admitted to a Pulmonary Intensive Care Unit for ARF. Blood gas measurements were as follows: arterial carbon dioxide tension (PaCO2), 72 ± 4 mm Hg SEM, range, 54 to 99 mm Hg; arterial oxygen þressure (PaO2), 38 ± 2 mm Hg SEM, range, 28 to 50 mm Hg; pHa, 7.32 ± 0.02 SEM, range, 7.25 to 7.37.
All patients had had an acute exacerbation of their underlying disease (two to eight days prior to
STATISTICS
The Mann-Whitney test was used to assess the statistical significance of differences between control subjects and COPD patients.10
Standard techniques of linear regression and correlation also were utilized.
RESULTS
Table 1 shows energy metabolism parameters and intracellular acid-base equilibrium indices of COPD patients with ARF.
A marked decrease of both muscle ATP and PCr contents as well as a significant decrease in TAN, the ATP-ADP ratio and ECP were found. No differences in ADP, AMP, or total Cr content were found between patients and controls.
Intracellular pH values were significantly (p<0.001) reduced and correlated to PaCO2 values (pHi = 7.76 – 0.0138 PaCO2, r = 0.77, n = 10, p<0.01), but not to
DISCUSSION
Low pHi, reduced ATP and PCr contents, and increased muscle and Lactfvp values characterize the skeletal muscle of the hypercapnic-hypoxemic COPD patients considered in our study.
The finding of an intracellular acidosis related to PaCO2 confirms the results of a previous study on a comparable group of subjects with COPD and ARF.2
The extent of the decrease of ATP and PCr content (about 30 to 35 percent of control values) is comparable to that found both in subjects with cardiogenic shock or
ACKNOWLEDGMENTS
We would like to express our gratitude to Mrs. Nancy Birch-Podini for skillful assistance in preparing the manuscript.
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Supported in part by CNR grant 0002504/11508323.
Manuscript received November 24; revision accepted March 13.