[Transient blood modifications of glycolysis in hypercapnic patients with artificial ventilation (author's transl)]

Ten patients with respiratory insufficiency (mean age: 63 years) are studied during the first 12 hours of intubation and assisted ventilation by a strong volumic respirator (Bennett MA1, FIO2: 0.40). Arterial blood samples are taken before, and after 30 min, one, two, four, six and 12 hours of assisted ventilation, for measurement of blood gases, acid-base equilibrium, haemoglobin and haematocrit, and, by various enzymatic methods, of lactate, pyruvate, ATP and 2,3-DPG concentrations. The PaCO2 rapidly decreases from 75 to 44 mmHg within 30 min ventilation. At the same time, SH+] decreases from 50 to 34 nmol/l. This "reventilation alkalosis" is still more marked later on (PaCO2: 34 mmHg; H+: nmol/l at the sixth hour). The mean PaO2 remains to about 70 mmHg during the assisted ventilation. The glycemia varies little and remains at a high level (140 mg%). The arterial blood lactate concentration progressively increases (from 1.6 to 2.5 mmol/l) at the second hour of ventilation, then decreases to 1.8 mmol/l at the 12th hour. The arterial blood pyruvate concentration also increases, with a peak at the fourth hour. The 2,3-DPG concentration significantly increases from the fourth hour on, whilst the blood ATP decrease is already significant at the first hour of assisted ventilation. These transient changes in glycolysis in chronic hypercapnic patients during assisted ventilation are similar to those observed in the dog when PaCO2 is rapidly normalized after a long term hypercapnia.