Seventy percent of surgeries performed in the United States are done in an outpatient setting.Pain Control after ambulatory surgery is very challenging because patients do not have access to fast and potent intravenous medications Pain after ambulatory surgery is poorly controlled in the United States with up to seventy five percent of patients having moderate to severe pain after ambulatory procedures. Postoperative pain have been associated with serious morbidity, including myocardial infarction and pulmonary embolism.

The use of intraoperative opioids can result in an exaggerated response to pain (hyperalgesia) and contribute to an exacerbation of pain after surgical procedures.Opioids are commonly given intraoperative, not in response to pain, but in response to hyperdynamic cardiovascular states. Esmolol is a short acting beta 1 antagonist that can be used to treat/prevent hyperdynamic states during surgery. More importantly, esmolol has been shown to have central antihyperalgesic effects that might contribute to a reduction in postoperative pain. It is therefore conceivable that the use of intraoperative esmolol instead of opioids to avoid hyperdynamic states during surgery can result in lower postoperative pain. Since postoperative pain can substantially affect postoperative quality of recovery, it is also conceivable that the use of intraoperative esmolol might result in an improved postoperative quality of recovery to surgical patients.

The main objective of the current study is to examine the effect of intraoperative esmolol on postoperative quality of recovery. A secondary objective is to examine the effect of esmolol on postoperative pain.

Significance: Postoperative pain after ambulatory surgery has been shown to be poorly managed in The United States. The goal of this study is to investigate if a change in the intraoperative pharmacologic management of patients undergoing ambulatory surgery can improve their postoperative quality of recovery and pain.

The research question is; does the use of intraoperative esmolol improve postoperative quality of recovery after ambulatory surgery? Does the use of intraoperative esmolol improve postoperative pain after ambulatory surgery?

The hypotheses of this study is; does the use of intraoperative esmolol improves postoperative quality of recovery after ambulatory surgery. The use of intraoperative esmolol reduces postoperative pain after ambulatory surgery.

We propose a randomized double blinded placebo controlled clinical trial. Healthy females undergoing outpatient surgery will be recruited . Before surgery patients will be tested for pain sensitivity and threshold using a Pathway Pain & sensory evaluation system (Medoc, Dunham, NC).Subjects will randomized using a computer generated table of random numbers to two groups: Active (Esmolol 0.5 mg/kg followed by an infusion of 5-15 mcg/kg/min titrated to keep heart rate between 50 and 70 BPM) or control (same volume of normal saline).The infusion will be discontinued at the end of the surgical procedure. Subjects will receive a standard anesthetic regimen: Induction (2 mg versed, 1-2mg /kg propofol and 0.6mg/kg of rocuronium), maintenance (Sevoflurane titrated to a Bispectral index between 40-60 and fentanyl 50 mcg q 10 minutes to maintain blood pressure within 20% of baseline value. Patients will receive at the end of surgery ondansetron 4 mg IV to prevent nausea and/or vomiting. The postoperative analgesic regimen will also be standardized with hydromorphone 0.4 mg every 15 minutes to treat pain greater than 4/10 (scale where 0 means no pain and 10 means the worst possible pain) and hydrocodone 10 mg/acetaminophen 325 for pain control after discharge. Patients will receive ephedrine 5 mg q5minutes if blood pressure is lower than 40% baseline or if the heart rate is less than 40 beats per minute. Before hospital discharge patients will again be tested for pain sensitivity and threshold using a Pathway Pain & sensory evaluation system (Medoc, Dunham, NC).

The primary outcome will be a validated instrument to measure postoperative quality of recovery (QoR-40) that will be administered to patients by an investigator unaware of group allocation at 24 hours after the surgery.Other outcomes to be evaluated include; postoperative pain sensitivity and threshold, postoperative opioid consumption, postoperative pain, time to meet discharge criteria using a validated instrument (PADDS).

Inclusion Criteria:

- Female patients Undergoing outpatient hysteroscopic myomectomy surgery ASA PS I and II Age between 18 and 64 years Fluent in English

Exclusion Criteria:

History of allergy to beta-blocker History of chronic opioid use Pregnant patients BMI greater than 35 History of EKG abnormalities or cardiac arrhythmias Beta-blocker medication usage.

Dropout criteria: Patient or surgeon request, Conversion of the surgery from laparoscopic to open.