Intensive buffering can keep pH above 7.2 for over 4 h during apnea: an experimental porcine study

• Published in: Acta anaesthesiologica Scandinavica 2013-01, Vol.57 (1), p.63-70
• Main Authors: HÖSTMAN, S., ENGSTRÖM, J., HEDENSTIERNA, G., LARSSON, A.
• Format: Article
• Language: English
• Subjects: Acid-Base Equilibrium - physiology; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Apnea - blood; Apnea - therapy; Arterial Pressure - physiology; Biological and medical sciences; Blood Chemical Analysis; Buffers; Carbon Dioxide - blood; Cardiac Output - physiology; Clinical Physiology; Diuresis; Electrolytes - blood; Hemoglobins - metabolism; Hydrogen-Ion Concentration; Klinisk fysiologi; Medical sciences; Respiration, Artificial; Sodium - urine; Swine; Tromethamine - therapeutic use; Water-Electrolyte Balance - physiology
• ISSN: 0001-5172; 1399-6576; 1399-6576
• DOI: 10.1111/aas.12012

Background Ventilation with low tidal volumes reduces mortality in acute respiratory distress syndrome. A further reduction of tidal volumes might be beneficial, and it is known that apneic oxygenation (no tidal volumes) with arteriovenous CO2 removal can keep acid‐base balance and oxygenation normal for at least 7 h in an acute lung injury model. We hypothesized that adequate buffering might be another approach and tested whether tris‐hydroxymethyl aminomethane (THAM) alone could keep pH at a physiological level during apneic oxygenation for 4 h. Methods Six pigs were anesthetized, muscle relaxed, and normoventilated. The lungs were recruited, and apneic oxygenation as well as administration of THAM, 20 mmol/kg/h, was initiated. The experiment ended after 270 min, except one that was studied for 6 h. Results Two animals died before the end of the experiment. Arterial pH and arterial carbon dioxide tension (PaCO2) changed from 7.5 (7.5, 7.5) to 7.3 (7.2, 7.3) kPa, P