[Relations between acid-base equilibrium and body temperature. Physiological concepts and practical applications].

Area of Science:

• Physiology
• Biochemistry

Context:

• The regulation of acid-base balance is crucial for physiological function.
• Body temperature significantly influences metabolic processes and acid-base status.
• Previous models of acid-base regulation did not fully integrate temperature effects across species.

Purpose:

• To validate H. Rahn's 1975 concept of hydrogen ion regulation in humans.
• To investigate the relationship between intracellular neutrality, extracellular fluid pH, and body temperature.
• To establish practical guidelines for managing acid-base status during hypothermic surgical procedures.

Summary:

• Rahn's concept posits that intracellular neutrality is maintained by imidazole-rich proteins, with extracellular fluid pH consistently higher (0.6-0.8 units) and independent of temperature.
• Experimental studies in humans undergoing hypothermic aorto-coronary bypass confirmed this concept.
• Acid-base status management during hypothermia can be achieved by ensuring intracellular neutrality and maintaining a specific partial pressure of carbon dioxide (PCO2).

Impact:

• Provides a unified framework for understanding acid-base regulation across species and temperatures.
• Offers a simplified method for correcting acid-base values during hypothermia, using measurements at 37°C.
• Enhances clinical management of patients undergoing hypothermic surgery by clarifying acid-base balance adjustments.