TRIS (HYDROXYMETHYL) AMINO-METHANE (THAM): A PEDIATRIC EVALUATION

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Abstract
Though the specific amounts and rates of administration of THAM to the fetus and newborn require further study, at recommended doses and rates of administration, THAM is an effective and useful alkalinizing, osmotic diuretic, anti-arrhythmic, and hypoglycemic agent. It has a definite value in the correction of acute respiratory and metabolic acidosis in pediatric patients. THAM can be recommended for: 1. Correction of the acidosis of asphyxia neonatorum, respiratory distress syndrome, status asthmaticus, bronchoscopy, complicated insulin resistant diabetic acidosis, salicylate and barbiturate intoxications, and cardiovascular failure. 2. Correction of the hyperglycemia of complicated insulin resistant diabetes. 3. Increase of elimination of toxic substances such as salicylate and barbiturate. 4. Titration of ACD blood, especially when used for exchange transfusions and for cardiovascular surgery. 5. Restoration of a normal rhythm after cardiac arrest. Caution in the use of THAM is dictated by the following considerations: 1. It is excreted mainly by the kidneys and may accumulate to above safe plasma levels in conditions of inadequate renal function. 2. It has a marked diuretic action and may induce elimination of water and electrolytes in amounts larger than administered. 3. It has a hypoglycemic effect, especially with doses above 500 mg/kg rapidly administered to patients with poor carbohydrate intake. 4. It has a depressant action on the respiratory center. 5. It causes tissue irritation or necrosis when extravasated or administered into a small vessel. 6. It may have a hyperkalemic effect. These complications may be avoided by determining the rate of intake and output, plasma levels of the pertinent substances, and, under ideal conditions, of THAM as it is administered. In addition, THAM should not be administered in rapid injections containing amounts larger than 500 mg/kg body weight and with inadequate carbohydrate intake; respiratory control should accompany administration or be readily available, and the administration should be undertaken only through a large vessel, preferably a vein. When an alkalinizing agent must be used it should be remembered that THAM does not compete with sodium bicarbonate since each has its own indications in the treatment of acid-base disturbances. In general, sodium bicarbonate can be safely administered in milder forms of acidosis, especially of the metabolic type. In more severe conditions in which the rapid alkalinization of body fluids is of the essence, especially if CO2 or sodium elimination is restricted, THAM is preferable. A dogmatic approach advocating the acceptance or rejection of either sodium bicarbonate or THAM should be replaced by a more objective evaluation of both drugs, using the one which is most indicated in a given situation. However, it is imperative that the present availability of THAM as a therapeutic agent does not result in its indiscriminate use by those who lack experience and proper laboratory support. The dangers of overcorrection of acidosis must not be minimized and always should be kept in mind by those administering alkalinizing agents.