Vitamins
Thiamine
Thiamine (in its active derivative, thiamine diphosphate) is a coenzyme for pyruvate dehydrogenase, so in deficiency states there is an accumulation of pyruvate and eventually lactate [12]. Lactic acidosis and the inability to utilize the Krebs cycle are the main causes of the neurologic (dry beriberi) and cardiac (wet beriberi) clinical manifestations of thiamine deficiency. Beriberi heart disease comprises three major physiologic derangements: 1) peripheral vasodilatation, 2) sodium and water retention, and 3) biventricular myocardial failure. The classical manifestations of thiamine deficiency are a high output failure, oliguria, edema, and lactic acidosis that usually run a chronic course [13]. An acute fulminant form of cardiac beriberi, known as shoshin, causes a very low cardiac output state and cardiovascular collapse, leading to death within hours to days [14].
Shoshin beriberi
has been described with two distinctive conditions:
1) low cardiac output and fulminant vascular collapse with marked cardiomegaly, hepatomegaly, and stocking-glove cyanosis and
2) an acute fatal form causing sudden death without clear-cut signs of cardiomegaly [15].
There are no pathognomonic clinical signs for shoshin beriberi. The chest X-ray study may reveal pulmonary edema and cardiomegaly. The echocardiogram may be normal, but hypokinesia and left ventricular dilatation are sometimes noted [14]. The laboratory diagnosis of thiamine deficiency is made by assessing erythrocyte transketolase activity at baseline and after addition of TPPE [16]. The two disadvantages of the test are: 1) a low availability of the test to most of the hospital laboratories, and 2) an inability of the test to distinguish between acute and chronic thiamine deficiency (e.g., alcoholism). Finally, the Blankenhorn’s diagnostic criteria for classic beriberi heart disease (enlarged heart with normal sinus rhythm, edema and elevated venous pressure, peripheral neuropathy, ST-T changes, no other etiology, history of thiamine deficiency, and clinical response to thiamine) are not very useful in the acute critical care setting. (JEM April 2004)