Abstract Rationale Perioperative anesthetic management plays a decisive role in the metabolic and respiratory stability of patients undergoing major cardiothoracic surgery. At high altitudes such as Bogotá (2,640 m.a.s.l.), hypobaric conditions modify baseline arterial blood gas (ABG) values, demanding precise intraoperative strategies including protective ventilation, individualized fluid therapy, and optimized hemodynamic targets. This study aimed to evaluate perioperative changes in ABG profiles using the Siggaard-Andersen method and to explore how adequate anesthetic management mitigates acid-base disturbances, reflecting improved metabolic homeostasis. Methods A retrospective cohort study included 196 adult patients who underwent major cardiothoracic surgery between 2022 and 2024. ABG parameters, pH, PaCO2, and HCO3⁻, were categorized as follows: pH: Acidemia ( 7.39), Normal (7.39-7.47), Alkalemia ( 7.47); PaCO2: Respiratory Alkalosis ( 28.3 mmHg), Normal (28.3-38.7), Respiratory Acidosis ( 38.7); HCO3⁻: Metabolic Acidosis ( 19.1 mmol/L), Normal (19.1-24.7), Metabolic Alkalosis ( 24.7). Pre and postoperative distributions were compared using Chi-square tests. Standardized intraoperative management included low-tidal-volume ventilation (6-8 mL/kg IBW), limited plateau pressure ( 30 cmH2O), goal-directed fluid therapy, and restrictive transfusion thresholds. Results Perioperative shifts were observed across all ABG markers. Postoperatively, 52.3% of patients transitioned from acidemia to normal pH, suggesting effective correction of metabolic and ventilatory imbalances. PaCO2 classification exhibited the largest fluctuation (61.5% of patients; p = 0.005), predominantly from respiratory alkalosis to normocapnia, consistent with improved ventilatory control under protective settings. HCO3⁻ remained stable in 62.5% (p = 0.43), reflecting metabolic compensation. These findings indicate that structured anesthetic protocols at high altitude can effectively normalize perioperative acid-base status. Conclusion Implementation of standardized perioperative anesthetic strategies—combining protective ventilation, guided fluid management, and individualized hemodynamic optimization—significantly impacts metabolic equilibrium in cardiothoracic surgery patients. The observed correction from preoperative acidemia toward normal pH values highlights the influence of precise ventilatory and metabolic control on postoperative recovery. Continuous monitoring of ABG dynamics using altitude-adjusted thresholds is essential for optimizing outcomes in high-altitude cardiac anesthesia. Future prospective trials should further correlate ventilatory parameters with clinical endpoints such as ICU stay, organ dysfunction, and mortality. This abstract is funded by: None
Romero et al. (Fri,) studied this question.