Nitroglycerin Plus Morphine on Iv Patient Controlled Analgesia for Abdominal Surgery: The Effect on Postoperative Pain

BACKGROUND: Some studies have reported the effect of nitroglycerin on the reduction of pain after surgery. OBJECTIVES: The primary goal of the current study was to evaluate the addition of nitroglycerin (as a nitric oxide donor) to morphine in patient-controlled analgesia. Besides, its effects on the reduction of pain and stability in hemodynamic indices after abdominal surgery are also investigated. METHODS: The current study was performed on 60 patients as candidates for abdominal surgery. Morphine (0.75 mg/mL) and nitroglycerin plus morphine (morphine 0.5 mg/mL + TNG 15 μg/mL) infusions were used for control and case groups, respectively, with the same induction of anesthesia. The severity of postoperative pain, hemodynamic indices of systolic blood pressure, diastolic pressure, heart rate, respiratory rate, and nausea were measured after surgery (immediately, 2, 6, 12, and 24 hours after surgery). RESULTS: The pain score decreased for both groups almost similarly. The mean systolic blood pressure was highly reduced in both groups. However, the mean diastolic blood pressure in the control group was considerably lower than that of the case group. Besides, the respiratory rate in the case group dramatically diminished and approached the normal value. CONCLUSIONS: Combined administration of nitroglycerin and morphine had no synergistic effects on reducing postoperative pain. However, it led to more stable hemodynamic indices and improved breathing, without any side effects.