Acute Respiratory Variations of Acid-base Equilibrium Clinical Trial
Official title:
Respiratory Alterations of Acid-base Equilibrium: Acute and Chronic Renal Response
Alterations of acid-base equilibrium are very common in critically ill patients. Thus,
understanding their pathophysiology and the possible compensatory mechanisms acting in
different organs may play an important role in better set the consequent clinical treatment.
The lung and the kidney are the two principal actors of such regulations. Although the
respiratory response to acid-base alterations is well understood, less information are
available for what the renal system is concerned. Such lack of information is partially due
to: 1) the historical consideration of the kidney as a "slow" organ, in response to
variations in acid-base equilibrium; 2) the lack of a monitoring system to closely assess
renal response.
Our group has recently developed a monitoring system aimed at analyzing, in a
quasi-continuous and non-invasive manner (every 10 min) the urinary profile in terms of
urinary pH and electrolyte concentrations (sodium, potassium, chloride, ammonium).
The investigators hypothesize that the renal system reacts to large as well as to minimal
variations of the acid-base equilibrium (especially induced by a variation in the
respiratory function) in a very fast way, modifying the urinary concentration (and therefore
the urinary excretion) of ammonium and some electrolytes (especially chloride).
Primary aim:
To investigate the acute renal response to respiratory alterations of acid-base equilibrium
in order to better understand the underlying physiological mechanisms and to evaluate the
validity of a renal monitoring system to indirectly assess the effectiveness of the
respiratory function.
Secondary aim:
To collect data on the chronic response of the renal system in patients affected by chronic
obstructive pulmonary disease (COPD), as well as on the acute response to acute variation of
the chronic respiratory acidosis characterizing patients affected by COPD exacerbation.
Study protol:
Mechanically ventilated patients will undergo controlled variation of the ventilatory
setting (hyperventilation vs. hypoventilation) in order to induce a controlled reduction or
increase in arterial partial pressure of carbon dioxide (and an increase or reduction of
arterial pH), within normal range of pH (7.35 - 7.45) During the variations, urinary
concentrations of electrolytes and pH will be monitored.
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Allocation: Non-Randomized, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Basic Science