THAM

Q: THAM should ideally be infused through central line.

A) True

B) False

Answer: A

THAM stands for Tromethamine (tris-hydroxymethyl aminomethane. Other less popular names are TRIS and trometamol. Although now rarely used, THAM is a viable option in mixed metabolic and respiratory acidosis, as it has two advantages over "bicarb" (H2CO3).

• no sodium load
• no generation of CO2, or may even reduce it

Unfortunately, it is not widely and commercially available, and many institutions prepare their own THAM.

Mechanism of action: THAM is an amino alcohol that buffers hydrogen ions by virtue of its amine (NH2) moiety (pKa = 7.7) via the following two reactions

1.  THAM-NH2 + H+  →  THAM-NH3+
2.  THAM-NH2 + H2O + CO2  →  THAM-NH3+ + HCO3-

The final product is the protonated form of THAM, which requires either a functioning kidney or dialysis. When given via peripheral IV line, extravasation may cause tissue necrosis. Central line is preferred.

#acid-base

References:

1. Nahas GG, Sutin KM, Fermon C, et al. Guidelines for the treatment of acidaemia with THAM. Drugs 1998; 55:191.

2. Kallet RH, Jasmer RM, Luce JM, et al. The treatment of acidosis in acute lung injury with tris-hydroxymethyl aminomethane (THAM). Am J Respir Crit Care Med 2000; 161:1149.

3. Weber T, Tschernich H, Sitzwohl C, et al. Tromethamine buffer modifies the depressant effect of permissive hypercapnia on myocardial contractility in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med 2000; 162:1361.

4. Holmdahl MH, Wiklund L, Wetterberg T, et al. The place of THAM in the management of acidemia in clinical practice. Acta Anaesthesiol Scand 2000; 44:524.

5. Radosevich MA, Wieruszewski PM, Wittwer ED. Tris-Hydroxymethyl Aminomethane in Critically Ill Adults: A Systematic Review. Anesth Analg 2023; 137:1007.