Thursday, July 3, 2008

Efficacy of Granisetron for Treatment of Postoperative Nausea


Patients and Methods

After obtaining approval from our institutional ethics committee and informed consent from each patient, we studied women who were American Society of Anesthesiologist physical status I (no organic, physiological, biochemical or psychiatric disturbances) and who experienced nausea lasting >10 minutes and/or vomiting within the 3 hours after recovery from general anaesthesia for breast surgery. Breast surgery included partial mastectomy, partial mastectomy with axillary dissection, modified radical mastectomy, and modified radical mastectomy with axillary dissection.

We excluded patients who had gastrointestinal disease, those who had a history of motion sickness and/or previous PONV, those who had taken antiemetics within 24 hours before surgery, and those who were pregnant, menstruating or taking hormonal therapy.

Patients were randomly assigned to study groups according to a computer-generated table of random numbers. Placebo or granisetron at four different doses (10 µg/kg, 20 µg/kg, 40 µg/kg and 80 µg/kg) was administered intravenously when patients experienced nausea lasting >10 minutes and/or vomiting within 3 hours after anaesthesia. Identical syringes containing each drug were prepared by personnel not otherwise involved in this study.

For preanaesthetic medication, patients received oral diazepam 5mg, as is routine in our institution. Anaesthesia was induced with intravenous propofol 2 mg/kg and intravenous fentanyl 2 µg/kg; intravenous vecuronium bromide 0.15 mg/kg was used to facilitate tracheal intubation. After tracheal intubation, anaesthesia was maintained with isoflurane 1.0–3.0% (inspired concentration) and nitrous oxide (N2O) 66% in oxygen, with controlled ventilation adjusted using an anaesthetic/respiratory gas analyzer to keep an end-tidal CO2 concentration of 35–40mm Hg. Neuromuscular block was achieved with vecuronium bromide and was antagonized by administering intravenous atropine 0.02 mg/kg and neostigmine 0.04 mg/kg at the end of surgery. The trachea was extubated when the patient was awake. Rectal temperature was monitored and maintained at 36.5–37.0°C using a warming pad. Postoperative analgesia was provided with indometacin 50mg administered rectally when the patient complained of pain. To maintain the integrity of our results, no patients received any intraoperative PONV prophylaxis.

The patients were observed for a 24-hour period after administration of the study drug in order to assess efficacy. All episodes of emetic symptoms (nausea, retching and vomiting) were recorded by nursing staff blinded to the study group allocation of the patient. These nurses observed the patients at intervals according to normal ward routine. Nausea was defined as a subjectively unpleasant feeling associated with an awareness of the urge to vomit; retching was defined as the labored, spasmodic, rhythmic contraction of the respiratory muscles without the expulsion of the gastric contents; and vomiting was defined as the forcing of gastric contents from the mouth.[3] Complete control of established PONV was defined as no emetic symptoms and no need for rescue antiemetic medication. If more than two episodes of vomiting occurred within the 24-hour period after study drug administration, a rescue antiemetic (e.g. domperidone rectally) was given, as is common practice in our institution. The details of any other adverse effects were recorded by the nurses who interviewed the patients.Statistical Analysis

Based on previously published data,[1,2] complete control of established PONV (which was regarded as the primary end-point) in patients receiving placebo would be 50%. An improvement from 50% to 90% with the use of granisetron would be considered clinically significant. To provide 80% power (beta = 0.2) to detect such an absolute difference using a test at a = 0.05, a sample size of 20 patients per group was required. Patient demographic data were analyzed by ANOVA with Bonferroni's correction for multiple comparison (continuous variables) and the Chi-square (χ2) test (discrete variables). The numbers of patients having complete control of established PONV (no emetic symptoms and no rescue medication), experiencing nausea, retching, vomiting or requiring a rescue antiemetic, and the incidence of adverse events were compared with Fisher's exact probability test. A p-value of <0.05 was considered to be significant.  Printer- Friendly Email This

Clin Drug Invest.  2006;26(4):203-208.  ©2006 Adis Data Information BV
This is a part of article Efficacy of Granisetron for Treatment of Postoperative Nausea Taken from "Atarax Hydroxyzine 25Mg" Information Blog

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