Trial Comparing Intrathecal Morphine With Placebo In Patients Undergoing Robotic Cardiac Surgery

Following Institutional Review Board approval and informed patient consent, 120 patients scheduled for elective robotic myocardial revascularization without cardiopulmonary bypass and anticipated intraoperative tracheal extubation will be studied. Patients will be randomized into one of two groups. Group A (placebo, control group) will receive intrathecal normal saline, Group B (morphine group) intrathecal morphine. All procedures will occur and administered medications given immediately prior to induction of general anesthesia in the operating room. Power analysis indicates that 60 patients per Group is appropriate, as further described below. Inclusion criteria include any patient undergoing elective robotic myocardial revascularization without anticipated use of cardiopulmonary bypass and with anticipated intraoperative tracheal extubation. Exclusion criteria include emergency surgery, ejection fraction less than 40%, preoperative use of inotropic agents or intraaortic balloon pump, anticipated use of cardiopulmonary bypass, previous cardiothoracic surgery, anticipated postoperative tracheal intubation, severe pulmonary disease, morbid obesity (BMI >35 kg/m2), severe renal dysfunction (creatinine > 1.5) recent history of opioid abuse, preoperative use of opioids, or any contraindication to intrathecal injection (patient refusal, difficult patient anatomy, pre-existing coagulopathy, morphine allergy).

Routine preoperative data will be collected (see Preoperative Data Sheet). Following intravenous access and routine mild sedation, each patient will be transported to the operating room and assume the sitting position. Following routine skin preparation, a routine lumbar intrathecal injection will be made via a 22-g spinal needle. The injectate will be either morphine (5 mcg/kg, maximum dose of 1 mg) or normal saline. The injectate will be prepared by a co-Investigator not directly involved in patient care. Thus, all preoperative, intraoperative, and postoperative caregivers will be blinded to intrathecal injectate composition (all injectates will be standardized to a total of 1.0 ml). All patients will have port incisions injected with 60 ml of 0.25% bupivacaine by the surgeon after the completion of surgery.

Following intrathecal injection, the patient will then assume the supine position. An arterial catheter will be inserted and general endotracheal anesthesia will be induced. Intraoperative anesthetic technique will be standardized and equivalent between Groups (see Intraoperative Anesthetic Protocol Sheet). The anesthetic protocol will allow tracheal extubation to occur in the operating room immediately after surgery (if clinically indicated).

Surgical technique will not be altered in any way. All patients in both Groups will be operated on by the same surgeon. Routine intraoperative data will be collected (see Intraoperative Data Sheet). In all patients, tracheal extubation will be attempted in the operating room immediately after surgery (if clinically indicated).

Both Groups will receive routine postoperative care and identical postoperative analgesic protocols to assess adequacy of postoperative analgesia (see Postoperative Analgesia Protocol and Postoperative Data Sheets). The American Pain Society Outcome Questionnaire (APS-POQ) will be administered to patients prior to discharge (see data sheet).15

Inclusion criteria

• patient undergoing elective robotic myocardial revascularization without anticipated use of cardiopulmonary bypass and with anticipated intraoperative tracheal extubation.

Exclusion criteria

• Emergency surgery
• Preoperative use of inotropes/IABP
• Preoperative use of opoids
• Ejection fraction less than 40%
• Anticipated use of cardiopulmonary bypass
• Previous cardiothoracic surgery
• Anticipated postoperative tracheal intubation
• severe pulmonary disease
• morbid obesity (BMI >35 kg/m2)
• severe hepatic impairment
• severe renal dysfunction (creatinine > 1.5)
• any contraindication to intrathecal injection (patient refusal, difficult patient anatomy, pre-existing coagulopathy, morphine allergy)