Perioperative Metabolism in Patients With Thyrotoxicosis, Possibilities of Its Correction

Abstract

In the past, thyroid surgery has been the most common cause of thyroid storm, but recently, preoperative drugs that create a euthyroid state before surgery have somewhat improved treatment outcomes. Therefore, the anesthesia of such operations is very important.
 The aim of this work: to evaluate the possibility of using dexmedetomidine for perioperative correction of metabolism in thyroidectomy under general anesthesia in patients with thyrotoxicosis.
 Materials and methods. The study was prospective, not randomized. The study involved 137 patients (53 men, 84 women, aged 21 to 76 years) with thyrotoxicosis, who underwent planned thyroidectomy under general anesthesia, using the inhalation anesthetic sevoflurane and the narcotic analgesic fentanyl, in low-flow artificial lung ventilation. Perioperative monitoring was complemented by the use of indirect calorimetry. The degree of preoperative risk of patients is ASA III-IV. In group I (n=71), situationally, during the operation, with a heart rate of > 90 beats/min, a selective β-blocker esmolol hydrochloride was administered intravenously (25-50 μg×kg-1×min-1) under the control of ECG and hemodynamic parameters until the heart rate normalizes. In group II (n=66) - dexmedetomidine – 0,1 μg×kg-1×h-1.
 Results and discussions. The initial metabolic parameters in both groups were high and amounted, respectively, 830±15 cal×min-1×m-2 in group I and 832 ± 13 cal×min-1× m-2 in group II, which exceeded their basal metabolic rate: in group I - by 54,9% and in group II - by 58,5% (p <0.01). At the stage of induction of anesthesia in group I, a depression of the hemodynamic profile was revealed, probably associated with the effect of the introduction of esmolol hydrochloride, which led to a decrease in oxygen transport without metabolic disturbances. At the stages of mobilization and removal of the thyroid gland, manifestations of hyperdynamia and hypermetabolism were observed in both groups. Metabolism at these stages, in group II, respectively, was lower, by 9,3% and 10,1%, than in group I. The degree of metabolic disorder, in group I, was 42,8% ± 2,3 % and 32,6 ± 1,8%, in group II – 31,2 ± 1,6% and 22,3 ± 1,2% (p <0.05). The blood cortisol level in group I was higher than in group II (p <0.05).
 Conclusions. Perioperative energy monitoring using indirect calorimetry allows timely detection of metabolic disorders and appropriate pathogenetic correction. The use of dexmedetomidine at a dose of 0.1 μg × kg-1 × h-1 is quite effective as an intravenous adjuvant for general anesthesia during thyroidectomy in patients with thyrotoxicosis.