Fentanyl Test Results And Its Association With Morphine Requirments In OSAS Children After Adenotonsillectomy

Objective The purpose of this study is to discuss the relationship between the result of fentanyl test and required dosageof morphine for children with OSAS after adenotonsillectomy; and to evaluate the ability of predicting requested dosage of morphine postoperatively.Methods From November 2013 to February 2014, children who were diagnosed with Obstructive Sleep Apnea Syndrome(OSAS) by electronic nasopharyngoscope and underwent selective adenotonsillectomy were selected as objects according to integration and elimination standard specified for the research at Children’s Hospital affiliated to Fudan University, Shanghai, China. Intubations were given after inhaled anesthesia or intravenous anesthetic induction, Sevoflurane was used for anesthetic maintenance without any usage of opiates during the operations. Observations of breath decreasing rates were made after 1 μg/kg fentanyl intravenous injection at the end of each operation when respiratory was recovered. The children were divided by the breath decreasing rates -with 50% decreasing rate of breath were positive result, and the rest were negative. After extubation, the children were evacuated to PACU where heart rate, blood pressure and respiratory rate were monitored. Blind tests were conducted during this period:pain evaluations were carried based on CHEOPS in every ten minutes and PAED were recorded at each CHEOPS whole point, later on, remedial analgesia with morphine(10μg/kg) were applied when CHEOPS score showed no less than 6 and oxygen inhalation was given when SpO2 was less than 95%. Once the patients’ Modified Aldrete Scores reached 9 or above, they could be transferred to normal wards. Comparisons on request of morphine dosage, pain evaluations, PAED evaluations, occurrence of adverse events, postoperative complications and recovery room dwell time were made. Besides Kaplan-Meier survival analysis were made between positive and negative patients according to the postoperative analgesic need of morphine. At the end take an ananalysis of diagnostic test for fentanyl test in detecting the patients who request less than routine morphine dosage postoperatively.Results Eighty patients were initially included in this study and 3 were excluded due to postoperative bucking. With observation of seventy-seven patients, the number of patinets with positive and negative was 25 and 52, respectively. The median of morphine requirement was 30μg/kg and 50μg/kg, respectively(P<0.05). The proportion of children who require morphine not less than 50μg/kg in PACU at each patinets with positive and negative was 12% and 52%, respectively(P<0.05).The rate of absence for morphine rescue analgesia in positive patients and negative patients was 20% and 1.9%, respectively(P<0.05). The sensitivity of the fentanyl test in detecting the patient who request less than routine morphine dosage postoperatively was 47%, and the specifity was 90%;Positive predictive value was 88%, negative predictive value was 52%.Conclusions The result of fentanyl test could reflect the requirement of morphine dosage in children with OSAS after adenotonsillectomy. The requirement of morphine dosage was in less in need in the positive patients than the negative patients.Fentanyl test performs as a rather accurate judgment if a patient would need a morphine dosage which less than routine of morphine or not, even if certain misdiagnosis rate was existed.