Methylamine will only exist in the atmosphere as a gas. It degrades by reacting with hydroxyl radicals, which have a half-life of 18 hours, or by interacting with ozone, which has a half-life of 540 days. Methylamine is expected to be moderately mobile in soil and will be present in the environment as a cation. Not expected to volatilize from soil, biodegradation is an important fate process in soil and water. In water, methylamine adsorbs to suspended solids and sediments. The potential for bioconcentration in aquatic organisms is low and hydrolysis is not expected to be a significant fate process.
Andrew D Bersten MB BS MD FCICM, In Oh's Intensive Care Handbook, 2019
Alkalizing agents – Sodium Bicarbonate, ‘Carbicarb’, Sodium Lactate and Trihydromethylaminomethane (THAM) methyl amine
The term "basifying agent" is preferred over "buffer". A true chemical buffer is one that resists pH changes when acid or base is added, whereas alkalizing agents in clinical practice increase the pH at any given PCO2. In other words, it increases SBE (see Figure 94.2). For example, a NaHCO3 dose of 1mmol/kg increases SBE by approximately 3mEq/L.
It is difficult to justify the use of alkalizing agents in hyperlactatemia and other organic acidosis. However, injection of NaHCO3 may be appropriate in the following situations:
•
Severe normal AGc acidosis
•
severe hyperkalemia
•
Methanol and Ethylene Glycol Poisoning
•
Tricyclic and salicylate excess.
NaHCO3 increases SBE by increasing SID. The active agent is sodium, not bicarbonate. High CO2 content (CO2tot about 1028mmol/L in 1M solution) creates two problems:
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The need for CO2-tight containers during autoclaving and storage
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Paradoxical possibility of intracellular respiratory acidosis.
major surge
and
is avoidable unless there is a substantial reduction in lung perfusion, such as in cardiac arrest. 4 The key is to dose slowly (over the course of 30-60 minutes).
The CO2tot of bicarbonate formulations can also be reduced at the expense of an increase in pH. in carbohydrates (
), half of the monovalent bicarbonate becomes divalent carbonate. However, complete elimination of bicarbonate as NaOH results in unacceptable alkalinity (pH = 14 for 1M solution), and peripheral hemolysis and endothelial damage may occur with peripheral administration. Sodium lactate (0.167M, pH 6.9) is an alternative, provided lactate metabolism is efficient. Note that lactate is replaced by bicarbonate when metabolized to pyruvate. It does not "generate" bicarbonate directly. 4
Weak bases (Btot) can counteract Atot to increase SBE without changing SID. THAM is tromethamine or tris buffer, a weak base with a pKa of 7.7 at 37°C. Because THAM is a "consumer" of CO2, transient hypocapnia coupled with an immediate increase in SBE can lead to sudden apnea. THAM accumulates in renal impairment and can cause hypoglycemia, hyperosmolarity, coagulation abnormalities, and potassium disturbances.