Comparison of THAM and sodium bicarbonate in resuscitation of the heart after ventricular fibrillation in dogs.
ABSTRACT Tris (hydroxymethyl) aminomethane (tromethamine or THAM) has been suggested as an effective substitute for sodium bicarbonate (NaHCO3) in the treatment of metabolic acidosis accompanying cardiac arrest. Even though several reports on its appraisal have been published, there is still no clear agreement on its therapeutic value. A double-blind study was therefore lndertaken to compare in 36 dogs the effectiveness of 0.6 M THAM, 0.3 M THAM, and NaHCO3 (0.892 mEq/ml) to correct metabolic acidosis produced during 3 minutes of cardiac fibrillation, followed by a 3-minute period of cardiac compression. The dogs were then defibrillated and observed for 45 minutes. One group of 8 dogs was treated with 0.9 percent NaCl infusion. Compared with 0.9 percent NaCl, both THAM and NaHCO3 were equally effective in correcting metabolic acidosis (p less than 0.05). Initially, 0.6 M THAM produced a more pronounced (p less than 0.05) elevation of blood pH, but this effect was not sustained during the later postdefibrillation period. There was little difference in the effect of either of these drugs on mean aortic pressure and total peripheral vascular resistance. It is concluded that adequate ventilation and effective cardiac compression are still the chief criteria on which the final outcome of cardiac resuscitation depends. Correction of metabolic acidosis is important supportive therapy, but either THAM or NaHCO3 can be used with comparatively equivalent effect.
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ABSTRACT: Inhibition of ventilatory drive may improve the sensation of dyspnea, because heightened ventilatory demand contributes to dyspnea. Tris-hydroxymethyl aminomethane (THAM) is an alkalizing agent that does not increase CO(2) production and exerts a depressant effect on respiration. The purpose of this study was to clarify the effect of THAM on dyspnea associated with increases in respiratory drive. We investigated the effects of THAM on dyspneic sensation produced by a combination of hypercapnia (mean PaCO(2)=52 mm Hg) and elastic loading (30 cm H(2)O/L) in 14 healthy subjects. The subjects were asked to rate their dyspneic sensation using a visual analogue scale (VAS) during the loaded breathing while monitoring ventilation using a pneumotachograph. THAM was infused at a rate of 0.4 mL/kg/minute for 10 minutes, and the effects of THAM on dyspnea and ventilation were evaluated by comparing the steady-state values of ventilatory variables and VAS score obtained before and after THAM administration. Administration of THAM corrected respiratory acidosis and was associated with significant improvements in VAS score and significant decreases in minute ventilation, respiratory frequency, and ventilatory drive. THAM administration greatly alleviates dyspneic sensation associated with the increase in respiratory drive and could be an effective therapy for treating severe dyspnea in patients with hypercapnia.Journal of pain and symptom management 10/2008; 37(2):212-9. · 2.42 Impact Factor
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ABSTRACT: To review the physiology and cardiovascular effects of the commonly used intravenous electrolytes. Abstracts, articles and published reviews of studies reported from 1966 to 2000 and identified through a MEDLINE search on cardiac arrhythmias and electrolytes. While isotonic saline solutions are used to improve the haemodynamic status in critically ill patients who are hypotensive and hypovolaemic, other intravenous solutions including potassium chloride, calcium chloride, magnesium sulphate and sodium or potassium phosphate as well as hypertonic saline and sodium bicabonate have unique and often therapeutically useful haemodynamic and antiarrhythmic effects. Potassium chloride solutions are used to treat hypokalaemia with a maximum speed of correction in an adult of 20 mmol per 30 minutes when an acute myocardial infarct is present. A greater infusion rate may be necessary when ventricular or supraventricular tachyarrhythmias are present although close ECG monitoring will be required. Magnesium sulphate (2-20 mmol) has been used for hypomagnesaemic and normomagnesaemic cardiac arrhythmias (particularly when digoxin induced) and calcium chloride (3.4-6.8 mmol) is used to treat hyperkalaemic and hypermagnesaemic cardiac arrhythmias. Both hypertonic sodium bicarbonate and sodium chloride solutions have antiarrhythmic effects that may be beneficial in conditions that include tricyclic poisoning, hyperkalaemia and bupivicaine toxicity, although sodium bicarbonate is generally used for tricyclic cardiotoxicity. Low cardiac output states and arrhythmias have also been reported in hypophosphataemic patients that are reversed by infusions of potassium or sodium phosphate. Intravenous potassium chloride, calcium chloride, magnesium sulphate, sodium and potassium phosphate, sodium bicarbonate and hypertonic saline can be used effectively to alter the haemodynamic status and manage cardiac arrhythmias. However, their indications are selective and complications may occur, so careful administration and monitoring are required with their use.Critical care and resuscitation: journal of the Australasian Academy of Critical Care Medicine 04/2001; 3(1):22-34. · 1.51 Impact Factor
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ABSTRACT: Severe acidemia (blood pH < 7.1 to 7.2) suppresses myocardial contractility, predisposes to cardiac arrhythmias, causes venoconstriction, and can decrease total peripheral vascular resistance and blood pressure, reduce hepatic blood flow, and impair oxygen delivery. These alterations in organ function can contribute to increased morbidity and mortality. Although it seemed logical to administer sodium bicarbonate to attenuate acidemia and therefore lessen the impact on cardiac function, the routine use of bicarbonate in the treatment of the most common causes of severe acidemia, diabetic ketoacidosis, lactic acidosis, and cardiac arrest, has been an issue of great controversy. Studies of animals and patients with these disorders have reported conflicting data on the benefits of bicarbonate, showing both beneficial and detrimental effects. Alternative alkalinizing agents, tris-hydroxymethyl aminomethane and Carbicarb, have shown some promise in studies of animals and humans, and reevaluation of these buffers in the treatment of severe acidemic states seems warranted. The potential value of base therapy in the treatment of severe acidemia remains an important issue, and further studies are required to determine which patients should be administered base therapy and what base should be used.American Journal of Kidney Diseases 10/2001; 38(4):703-27. · 5.29 Impact Factor