Alcaliniser une acidose lactique ?. Effets du bicarbonate de sodium sur l'état hémodynamique et l'oxygénation tissulaire

We designed a prospective, placebo controlled clinical study to determine whether correction of acidemia using sodium bicarbonate (1 mmol.kg^-1 body weight) improves hemodynamic variables and tissue oxygenation in patient being mechanically ventilated with lactic acidosis (HCO₃ < 20 mmol.l^-1, plasma lactate > 2.5 mmol.l^-1, PaCO₂ > 35 mmHg) and no severe renal dysfunction (creatinine < 300 μmol.l^-1). Injection of sodium chloride (same volume, same sodium load) serve as control. Measurements were performed before (T0), 30, and 60 minutes after injection. Sodium bicarbonate increased arterial pH (T0: 7.19 ± 0.10, T30: 7.24 ± 0.09*, T60: 7.23 ± 0.09* p < 0.01), arterial partial pressure of CO₂ (T0; 39 ± 4, T30: 43 ± 6*, T60: 43 ± 4 mmHg p < 0.01), venous partial pressure of CO₂ (T0: 46 ± 6, T30: 50 ± 6*, T60: 50 ± 6* mmHg p < 0.01). Sodium bicarbonate not improve cardiac index (CI) (T0: 3.6 ± 1.1, T30: 3.4 ± 1.0, T60 - 3.5 ± 1.2 l.min.^-1.m^-2) or mean arterial pressure (Pā T0: 73 ± 21 - T30: 71 ± 18 - T60: 70 ± 17 mmHg). Sodium bicarbonate not worsen tissue oxygenation parameters such as oxygen delivrance (ḊO₂) (T0: 570 ± 230 - T30: 550 ± 220 - T60: 550 ± 250 l.min^-1.m^-2), oxygen consumption (V̇O₂) (T0: 129 ± 59 - T30: 130 ± 60 - T60: 126 ± 61 l.min.^-1.m^-2) and oxygen extraction (OER) (T0: 24.2 ± 3.2 - T30: 25.7 ± 2.4 - T60: 24.3 ± 2.8%).