Hypertonic saline: An alternative therapy in TCA overdoses failed to respond sodium bicarbonate
To the Editor:
I would like to thank Dr. Bebarta et al. for their interesting case report of a tricyclic antidepressant (TCA) overdose presenting with a Brugada pattern that failed to respond sodium bicarbonate and discuss the use of hypertonic saline (7.5%) as an alternative therapy in TCA overdoses that fail to respond the classical therapy.
The evidence supporting the usage of hypertonic saline is limited and contradictory. One study showed no improvement when hypertonic saline was added to sodium bicarbonate therapy (Citation3). In two recent studies (Citation4,Citation5) hypertonic saline corrected hypotension and QRS prolongation in experimental swine models. In the first study, 7.5% saline and 6% dextran were found to be effective in TCA overdose while normal saline was not (Citation4). In the second study, 7.5% saline was found to be superior to both sodium bicarbonate and hyperventilation in reversing QRS prolongation and hypotension (Citation5). However, hypertonic saline failed to establish an alkaline pH, which was shown to prevent cardiac arrhythmias (Citation3). A more recent publication reported a 29-year-old 78 kg woman who presented to the emergency department after ingesting approximately 8 g of nortriptyline. The patient was hypotensive and had a QRS duration of 124 msec. She transiently improved following a bolus 3 L normal saline and 200 mL (4 ampoules, 8.4% NaHCO3) of sodium bicarbonate. However, in the intensive care unit she had recurrent hypotension resistant to an additional 5 L normal saline and to vasopressor therapy (dopamine 20 mcg/kg per minute and norepinephrine at 22 mcg/minute). Hypertonic saline (200 mL, 7.5% NaCl) was administered and the QRS prolongation and hypotension improved within three minutes. In another study, NaHCO3 was found to be more effective in reversing the cardiac effects of TCA than alkalinazation and sodium chloride alone (Citation8).
The patient reported by McKinney (Citation6) improved after the administration of 200 ml of 7.5% NaCl (approximately 175 mEq of sodium) despite the lack of response to 200 ml NaHCO3 (approximately 200 mEql of sodium). Dr. Bebarta et al. administered a total of 300 mEq sodium by giving NaHCO3, with no response in the Brugada pattern. It would be interesting to know if the Brugada pattern would have responded to the administration of hypertonic saline.
The side effects of hypertonic saline (hypernatremia and hyperchloremic acidosis) should be considered. Hypernatremia developed in the swine group treated with hypertonic saline (pre-treatment sodium levels of 138 ± 5 mEql/L vs post-treatment levels of 157 ± 4 mEql/L) whereas there was no hypernatremia in the other groups (Citation5).
In conclusion, recent experimental studies support the effectiveness of hypertonic saline, but the data proving the best therapy in TCA overdoses are conflicting. Further studies are needed to identify the clear effects of hypertonic saline, alkalinization, and NaHCO3.
This study was supported by Akdeniz University Foundation.
References
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