Renal Function in Respiratory Failure Effects of Hypoxia, Hyperoxia and Hypercapnia

Our plain-English summary of Renal Function in Respiratory Failure Effects of Hypoxia, Hyperoxia and Hypercapnia, by K.H. Kilburn, A.R. Dowell (1971).

The study

• Authors: K.H. Kilburn, A.R. Dowell
• Published: Archives of Internal Medicine, Volume 127. April 1971
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1971 article concerns kidney function, not asbestos. The authors studied 27 men with respiratory failure and fluid retention. All had low blood oxygen and 24 had high blood carbon dioxide. Fluid retention occurred in 23% of 176 episodes of acute respiratory failure. During respiratory failure, patients excreted a water load of 20 ml per kilogram of body weight poorly: in 26 tests on 18 patients, only three excreted 70% or more within four hours. In short experiments, patients breathed low-oxygen, high-oxygen or carbon dioxide mixtures. In seven patients given extra oxygen, kidney plasma flow fell 27% and filtration fell 21%. Lowering oxygen raised kidney function at first, but function dropped sharply once arterial oxygen fell below 40 mm Hg. Carbon dioxide had no measurable effect until it reached 65 mm Hg. In the carbon dioxide experiment, raising the average level cut urine production 66% and sodium excretion 55%. The authors concluded that these effects may help explain fluid retention in such patients. They noted the patients were recovering and the exposures were brief.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Clinical physiological study: kidney clearance measurements in patients recovering from respiratory failure. Measurements were taken while patients breathed air and then low-oxygen, high-oxygen or carbon dioxide gas mixtures. The article also describes individual patients.
• Who was studied: 27 men with respiratory failure accompanied by fluid retention (edema), mostly during flare-ups of chronic bronchitis. All were hypoxic and 24 were hypercapnic. Fluid retention occurred in 23% of 176 episodes of acute respiratory failure seen over three years.
• Exposure: Not asbestos. Patients briefly breathed gas mixtures: low-oxygen mixtures (eight patients, arterial oxygen below 40 mm Hg), high-oxygen mixtures (seven patients), and 6% to 8% carbon dioxide in 21% oxygen. Water loads of 20 ml per kg of body weight were also given.
• Main results:
  • Patients excreted water loads of 20 ml per kg of body weight poorly during respiratory failure. In the table covering 18 patients (26 tests), only three excreted 70% or more of the water load within four hours.
  • In eight patients made more hypoxic, arterial oxygen tension was lowered from a baseline mean of 54 mm Hg to a mean of 30 mm Hg, and mean urine excretion decreased.
  • Kidney function rose as oxygen was lowered, but fell abruptly once hypoxia became severe, with arterial oxygen below 40 mm Hg.
  • In seven patients given high oxygen (hyperoxia), renal plasma flow was reduced 27% and glomerular filtration rate (GFR) 21%.
  • With hyperoxia, sodium excretion decreased 54%.
  • Arterial carbon dioxide tension had no measurable effect until it reached 65 mm Hg.
  • In the acute carbon dioxide experiment, the average carbon dioxide tension was raised (printed as 578 to 742 mm Hg, apparently 57.8 to 74.2). Urine production fell 66% and free water clearance fell 89%.
  • In the same carbon dioxide experiment, renal plasma flow fell 25% and sodium excretion fell 55%. The smaller fall in GFR was not statistically significant.
• The authors' conclusion: The authors concluded that these effects of acute changes in blood oxygen and carbon dioxide may help explain fluid retention in patients with cor pulmonale who have severe hypercapnia, severe hypoxia, or both.
• Limitations the authors state:
  • The patients were convalescent and were studied during an induced water diuresis, with brief clearance periods.
  • The authors did not establish with certainty whether high oxygen and high carbon dioxide act together (additively).
  • The combined effect of severe hypoxia and severe hypercapnia was not tested in patients, because of the discomfort it would cause.
  • The authors could not prove with certainty that the mechanism is a direct effect on the kidney's blood vessels.

Topics

Medical terms in this study, explained in our Lexicon: Hypoxia.

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