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).

Study Overview

• Status: Unknown
• Conditions: Acute Respiratory Variations of Acid-base Equilibrium
• Intervention / Treatment: Other: Increase minute ventilation; Other: Decrease minute ventilation

Detailed 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.

• Study Type: Interventional
• Enrollment (Actual): 50
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Italy
  • Milan, Italy, 20122
    • Terapia Intensiva Postoperatoria; Rianimazione Generale - Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Hyperventilation; Minute ventilation will be increased of about 30% of baseline value, through an increase in respiratory rate	Other: Increase minute ventilation; Respiratory rate will be increase in order to have a 30% increase of minute ventilation
Experimental: Hypoventilation; Minute ventilation will be decreased of about 30% of baseline value, through a decrease in respiratory rate	Other: Decrease minute ventilation; Respiratory rate will be decrease in order to have a 30% decrease of minute ventilation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Variations in urinary electrolyte concentrations and pH	From 0 to 4 hours

Collaborators and Investigators

• Sponsor: Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico

Study record dates

Study Major Dates

• Study Start: February 1, 2012
• Primary Completion (Anticipated): November 1, 2015
• Study Completion (Anticipated): November 1, 2015

Study Registration Dates

• First Submitted: February 23, 2012
• First Submitted That Met QC Criteria: February 28, 2012
• First Posted (Estimate): February 29, 2012

Study Record Updates

• Last Update Posted (Estimate): November 10, 2015
• Last Update Submitted That Met QC Criteria: November 7, 2015
• Last Verified: November 1, 2015

More Information

Terms related to this study

• Keywords: acid-base equilibrium; renal system; urinary electrolytes
• Other Study ID Numbers: 842