Understanding the Acid-Base Response to Respiratory Derangements: Finding, and Clinically Applying, the In Vivo Base...

Area of Science:

• Physiology
• Acid-Base Balance
• Respiratory Medicine

Background:

• Understanding in vivo acid-base regulation is crucial for clinical management.
• Existing models for calculating base excess may not accurately reflect physiological responses to carbon dioxide fluctuations.

Purpose of the Study:

• To evaluate the in vivo base excess response to acute changes in arterial carbon dioxide.
• To determine an appropriate buffer power coefficient for clinical application.

Main Methods:

• Secondary analysis of data from three experimental studies involving canine and human subjects.
• Eighty-nine carbon dioxide exposure experiments were analyzed using linear regression.
• Arterial carbon dioxide levels were manipulated via environmental chambers or mechanical ventilation.

Main Results:

• Significant individual variations in base excess response to carbon dioxide were observed.
• The standard buffer power coefficient of 16.2 showed different baselines and slopes across studies.
• A buffer power coefficient of 12.1 (95% CI, 9.1-15.1) demonstrated a more appropriate in vivo base excess equation.

Conclusions:

• In vivo carbon dioxide changes elicit clinically relevant base excess variations in individual patients.
• The buffer power coefficient of 16.2 may be inappropriate for in vivo calculations and requires validation.
• A revised coefficient of 12.1 warrants further investigation for general clinical use.