Effects of esmolol on QTc interval changes during tracheal intubation: a systematic review

The effects of acetylcholinesterase inhibitors on morbidity after general anesthesia and surgery

Non-depolarizing neuromuscular blocking agents are used during general anesthesia to facilitate intubation and optimize surgical conditions. When patients leave the operating room after surgery, postoperative residual neuromuscular block occurs frequently, increasing vulnerability to respiratory complications such as hypoxemia and unplanned postoperative mechanical ventilation. To restore neuromuscular transmission and skeletal muscle strength, anesthesiologists typically administer peripherally acting acetylcholinesterase inhibitors such as neostigmine. However, neostigmine's desirable effects have a narrow therapeutic range. Even at recommended dose (15-50 μg/kg), neostigmine induces nicotinic (upper airway muscle weakness leading to dysphagia and upper airway obstruction, and decreased maximum inspiratory airflow) and muscarinic (blurred vision, bronchial constriction, abdominal cramping and nausea) side effects. Recent data have questioned as to whether neostigmine reversal of neuromuscular blockade improves relevant patient outcomes such as postoperative respiratory and perioperative cardiovascular complications. A central strategy to avoid side effects of neuromuscular blocking agents is their judicious use based on quantitative monitoring of neuromuscular transmission using repetitive peripheral nerve stimulation (train-of-four ratio). Peripherally acting acetylcholinesterase inhibitors such as neostigmine should then only be administered when indicated and dosed based on results of the train-of-four ratio.

Esmolol Infusion Reduces Blood Loss and Opiate Consumption during Fertility Preserving Myomectomy

Objectives

The objective of this study is to evaluate the effect of esmolol-induced hypotensive anesthesia (EIHA) on intra-operative (IO) bleeding during open myomectomy.

Patients and Methods

Eighty-eight women were randomly divided into the study group received EIHA without uterine tourniquet and control group who received normotensive anesthesia with uterine tourniquet. EIHA was provided as priming dose of esmolol (0.5 mg.kg^-1) before the induction of anesthesia and esmolol infusion (0.05-0.3 mg.kg^-1.min^-1) to maintain mean arterial pressure at 60-70 mmHg that was stopped on completion of myomectomy. Fentanyl was used as IO analgesia (loading dose: 1.0 μg.kg^-1 then infusion of 0.2-0.4 μg.kg^-1.h^-1). All patients received 6% hydroxyethyl starch (HES; initially, 3 mL.kg^-1 over 5-10 minutes and supplemental doses according to requirements) and Lactated Ringer's solution (LR; 5 mL.kg^-1.h^-1). Trigger for blood transfusion was hemoglobin concentration (HBC) <7 g.dL^-1. Study outcomes included the extent of postoperative (PO) HBC deficit in relation to preoperative HBC, frequency of tourniquet application for the study patients, and total fentanyl consumption.

Results

EIHA significantly reduced blood pressure measures since laryngoscopy and tracheal intubation till the end of surgery in the study group compared to control group. Eight study patients (18.9%) required tourniquet application for control of bleeding; however, amount of IO blood loss; total field visibility score and PO HBC deficit were non significantly lower in the study group. EIHA allowed significant reduction of the IO amount of LR and additional amounts of HES infusions. Study patients group consumed significantly lower IO fentanyl doses with significantly longer duration till the 1^st PO request and the number of additional fentanyl, and lower numeric rating scale scores in study group compared to controls.

Conclusion

Open myomectomy under EIHA is feasible and safe and allows fertility-sparing with minimal risk of blood transfusion. The applied procedure of EIHA allowed blunting of pressor reflexes secondary to LIT, surgical stresses and extubation, and allowed reduction of IO and PO opioid doses.