Effect of Dexmedetomidine on Plasmatic Cortisol Response in Transsphenoidal Surgery

Effect of Dexmedetomidine as Anesthetic Coadjuvant on Plasmatic Cortisol Response in Transsphenoidal Surgery for Pituitary Tumors

Use of dexmedetomidine in pituitary tumor resection surgery as adjuvant drug and its relation to cortisol levels during postoperative period.

Transsphenoidal resection of pituitary tumors is the neurosurgical procedure of choice to remove most of the tumors of the sellar region. Sometimes the intervention produces dysfunction of the hypothalamic-pituitary axis, and although most are transient, the risk associated with post-operative hypocortisolism determines its evaluation early in the postoperative period and the possibility of steroidal supplementation posteriorly. It is described that dexmedetomidine can be used as an adjuvant drug in this type of surgery being useful in reduction of total consumption of opioids and anesthetic gases, maintain hemodynamic stability and less time to recovery from anesthesia. Due to its sympatholytic effect, dexmedetomidine has been found to alter the intraoperative common neuroendocrine response generating lower levels of cortisol in the postoperative period than patients in which is not used. The main objective of this study is to evaluate corticosteroid axis response (cortisol and adrenocorticotropic hormone) in patients undergoing transsphenoidal surgery under anesthesia with dexmedetomidine. A single-center randomized double-blind clinical trial will be conducted that will compare two groups of patients, one of which will be given dexmedetomidine (Dex group) and another group who will receive a placebo (control group). In addition the incidence of perioperative complications (nausea, vomiting, diabetes insipidus), intraoperative hemodynamics and patient comfort. The investigators expect that the normal stress response to surgery measured by cortisol and adrenocorticotropic hormone in the postoperative period will be reduced in the dexmedetomidine arm. This effect should be transient and attributed to use of dexmedetomidine and not to surgery.

Use of crystalloid solution (sodium chloride 0.9%), injection pump programmed with drug "Dexmedetomidine" with 1 mcg/kg in 10 minutes, infusion 0.7 mcg/kg/h.

At start of anesthesia, bolus of 1 mcg/kg of dexmedetomidine over 10 minutes and then infusion of 0.7 mcg/kg/h during surgery will be administered.

Clinical diagnosis by urine output (polyuria over 3 liters or urine per day) and/or hypernatremia (plasmatic sodium over 145 meq/L)

Inclusion Criteria: American Society of Anesthesiologists physical status I or II. Pituitary tumour: non-functional macroadenoma, Rathke's cleft cyst, acromegaly. Normal hypothalamic-pituitary-adrenal axis by hormone levels measurement previous to surgery. Exclusion Criteria: Cushing disease. Pituitary apoplexy. Craniopharyngioma. Chronic corticosteroid use. Hemodynamic instability. Altered consciousness (Glasgow Coma Scale score less than 15). Atrioventricular block in any degree. Preoperative bradycardia. Alpha 2 agonist use (clonidine, alpha-methyldopa) Pregnancy or breast feeding. Known allergy to any of the study drugs.

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