Respiratory Alterations of Acid-base Equilibrium: Acute and Chronic Renal Response

Institute of Hospitalization and Scientific Care (IRCCS)

Status: Unknown

Conditions: Acute Respiratory Variations of Acid-base Equilibrium

Treatments: Other: Increase minute ventilation; Other: Decrease minute ventilation

Study type: Interventional

Funder types: Other

Identifiers

NCT01540916

842

Details and patient eligibility

About

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).

Full description

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.

Enrollment: 50 patients

Sex: All

Ages: 16+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. Presence of mechanical ventilation
2. Presence of arterial and central venous line
3. Presence of urinary catheter

Exclusion criteria

1. acute or chronic renal failure with anuria
2. presence of continuous renal replacement therapy
3. hemodynamic instability
4. less than 16 years of age

Trial design

Primary purpose: Basic Science

Allocation: Non-Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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50 participants in 2 patient groups

Hyperventilation

Experimental group

Description:

Minute ventilation will be increased of about 30% of baseline value, through an increase in respiratory rate

Treatment:

Other: Increase minute ventilation

Hypoventilation

Experimental group

Description:

Minute ventilation will be decreased of about 30% of baseline value, through a decrease in respiratory rate

Treatment:

Other: Decrease minute ventilation