Friday, July 01, 2011

Serum potassium levels after cardiac arrest

Here's a really interesting study that looked at serum potassium levels after cardiac arrest:

The mean potassium level was 3.9±0.9mmol/l and thus within the reference range of 3.5–5.0mmol/l, but the overall prevalence of hypokalaemia was high (31.0%). Moderate rather than severe hypokalaemia was typically observed..
Among those six patients with extreme hypokalaemia defined as a potassium levels below the 2.5 percentile, two adult females were identified to suffer from previously untreated body scheme disorder with furosemide abuse (potassium 1.1 and 1.4mmol/l). Another patient (potassium 2.1mmol/l) suffered from poorly controlled bulimia nervosa and acute diarrhoea due to GI infection and one (potassium 2.4mmol/l) from untreated bulimic anorexia...
In contrast to moderately reduced potassium which is a frequent finding in adult patients at the time of admission for non-traumatic cardiac arrest, severe hypokalaemia is uncommon. The high prevalence of patients with body dysmorphophobic eating disorders in this group underscores accidental self-induced hypokalaemia may evolve as an important differential diagnosis in cardiac arrest in young female patients.

Mild to moderate hypokalemia after cardiac arrest may be redistributional, due either to endogenous catecholamines associated with the cardiac event or to administered epinephrine and therefore may not reflect pre-arrest potassium levels. In this study severe hypokalemia was associated with eating disorders and extreme dieting.

That, you may recall, is what caused Terri Schiavo's cardiac arrest:

Upon admission to the hospital, her serum potassium level was noted to be very low, at 2.0 mEq/L...
Her medical chart contained a note that "she apparently has been trying to keep her weight down with dieting by herself, drinking liquids most of the time during the day and drinking about 10–15 glasses of iced tea”...
Terri's husband, Michael, later filed and won a malpractice suit against her obstetrician, Dr. Stephen Igel, who was treating her for infertility, on the basis that he failed to diagnose bulimia as the cause of her infertility.

Postmortem examination, including a molecular autopsy, found no evidence of structural heart disease or channelopathy.

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