A longitudinal evaluation of thyroid function in critically ill surgical patients.

Thyroid hormone alterations (known as the "sick-euthyroid syndrome") are common following major surgery, but the time course for appearance and recovery from these alterations has not previously been longitudinally studied in a large group of surgical patients. The authors prospectively studied 59 patients undergoing major surgery (coronary artery bypass grafting, pneumonectomy, or subtotal colectomy). Compared with preoperative values, the mean serum T4, T3, free T3, and TSH concentrations decreased significantly (p less than 0.05) following surgery. Serum reverse T3 and T3 resin uptake index increased, while free T4 levels remained unchanged. These changes were seen within 6 hours of surgery and normalized by 1 week after surgery. Although the serum TSH response to TRH was normal before and after surgery in 56 of the 59 patients, the maximal TRH-induced increase in serum TSH and the integrated serum TSH response to TRH were suppressed in the early perioperative period. This postoperative TSH suppression correlated with elevated postoperative plasma dopamine concentrations (r = 0.57, p less than 0.05). Three patients with compensated primary hypothyroidism were detected in the study and represent the first documentation of serial thyroid hormone and TSH levels in hypothyroid patients undergoing major surgery. These patients had similar changes in thyroid hormone values compared with euthyroid patients. The serum TSH response to TRH was suppressed into the normal range in two of these patients on the day following surgery. The authors conclude that the sick-euthyroid syndrome occurs within a few hours of major surgery and remits with convalescence. Postoperative decreases in serum TSH may mask the diagnosis of hypothyroidism. Surgical consultants should be aware of these rapid postoperative changes so that thyroid function tests are properly interpreted in patients who have undergone major surgery.

Plasma catecholamine and hemodynamic responses to the placement of epinephrine-impregnated gingival retraction cord.

A double-blind randomized crossover study was conducted to measure the changes in heart rate, mean arterial blood pressure, pulse pressure product, and plasma catecholamine levels for 60 minutes after the placement of racemic (r) epinephrine- or alum-impregnated retraction cords in intact gingival sulci of nine healthy volunteers. The r-epinephrine-impregnated cord produced significant (p less than 0.01) increases in plasma epinephrine concentrations after 60 minutes, but there were no epinephrine-induced hemodynamic changes. According to these findings, r-epinephrine-impregnated gingival retraction cord placed in an intact, nonlacerated gingival sulcus in a healthy young adult should produce no significant hemodynamic response. It is not known how the placement of epinephrine-impregnated retraction cord would affect elderly or medically compromised patients or patients with lacerated or periodontally involved gingivae.

Glucagon: hormone or therapeutic agent?

Glucagon is an important therapeutic agent in critical care medicine. Although its endogenous hormonal functions have been well described, its clinical uses are rarely discussed. Glucagon is effective in the treatment of hypoglycemia, cardiogenic shock and heart failure, propranolol overdose, esophageal meat impaction, ureteral colic due to calculi, and acute diverticulitis. It may prove useful in the treatment of endotoxin and hypovolemic shock as well as toxicity due to excesses of procainamide, quinidine, or ouabain.