Hydrochloric acid (HCl) is proposed as the most efficient way of rapidly and selectively correcting the deficits in hydrogen and chloride ions which characterize metabolic alkalosis. Suggested indications for HCl therapy are ( Brimjoyl|Je,etllna/ 1989; BIimiOyll§,§n,d Kahn 1990,):
1. serious clinical complications due to the alkalosis (coma, arrhythmias);
2. contraindications to or ineffectiveness of other treatments;
3. severe alkalemia (arterial pH > 7.55);
4. respiratory failure with hypercapnia and/or hypoxemia.
The efficiency of HCl in reversing the alkalosis has been reported in several clinical studies ( Table... 1).
Table 1 Clinical experience of HCl infusion in the treatment of metabolic alkalosis: administration modalities and complications
One case of pulmonary edema due to HCl therapy, which was attributed to the amount of fluid required to correct the alkalosis, has been reported. Hemolysis has been reported in animal experiments but not in clinical series. Vascular and perivascular necrosis have been observed in earlier series, after HCl infusion into a peripheral vein. Extensive tissue necrosis has only been reported after leakage or infusion to extravascular sites.
HCl can be infused into the superior vena cava without complications, provided that adequate precautions are respected. HCl is prepared in a glass bottle as a 250-or 500-mmol/l solution (25 or 50 ml of 36 per cent HCl in 1 liter of sterile water). After very careful verification of the correct position of the catheter tip on a chest radiograph, the solution is infused at a rate of 1 ml/kg/h without being mixed with non-electrolytic solutions. Arterial blood gases are measured every 2 h (500 mmol/l) or 4 h (250 mmol/l), and the infusion is discontinued when the alkalosis is reversed (e.g. base excess below zero). When rapid correction is required, a 1000-mmol/l solution may be infused at the same rate while blood gases are measured hourly ( Br[miouJle..and Kahn 19.90.). Animal experiments have shown that there are no complications when HCl is administered at a rate of 2 mmol/kg/h, but a syndrome similar to adult respiratory distress syndrome commonly occurs at a rate of 3 mmol/kg/h. Metabolic alkalosis may relapse after achievement of the HCl infusion if generating or maintenance factors have not been corrected.
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