Association between fentanyl test results and rescue morphine requirements in children after adenotonsillectomy.

PURPOSE: Preoperative sleep study helps to predict post-adenotonsillectomy morphine requirements. However, in some institutions, many suspected children with obstructive sleep apnoea syndrome have an adenotonsillectomy without polysomnography assessments. This study investigated the relationship between the results of a fentanyl test performed before extubation and the postoperative morphine requirements in children after adenotonsillectomy. METHODS: Intravenous fentanyl (1 µg/kg) was given as a test before extubation when spontaneous ventilation was restored in 80 children aged 3-7 years who underwent adenotonsillectomy. The result was considered positive if the patient's respiratory rate decreased >50% after the test. In the recovery room, pain was assessed every 10 min using the Children's Hospital of Eastern Ontario Pain Scale. Rescue morphine (10 µg/kg) was given when the score was ≥6. RESULTS: The median [IQR (range)] cumulative morphine consumption rates for children with a positive result (n = 25) and a negative result (n = 52) were 30 (20, 40) and 50 (40, 50) µg/kg, respectively (P = 0.002). Eighty-eight percent of the positive-result patients and 48% of the negative-result patients were light consumers of morphine (cumulative dose <50 µg/kg) (P = 0.001). CONCLUSIONS: We conclude that children with a positive result after a fentanyl test require less morphine to achieve comfort than those with a negative result. CLINICALTRIALS. GOV ID: NCT02484222.

Effect of a mixture of iprobenfos and malathion on the development of malathion resistance in the mosquito Culex pipiens pallens Coq.

A malathion-resistant (RM) strain of Culex pipiens pallens Coq was obtained by successively selecting a field population with malathion in the laboratory. The synergistic effect of iprobenfos on malathion toxicity and alpha-naphthyl acetate (alpha-NA) esterase assay revealed that malathion resistance in the RM strain was associated with increased alpha-NA esterase activity and the synergism was mainly due to the inhibition by iprobenfos of this activity. There was no difference in alpha-NA esterase activity between the larvae and female adults in the susceptible (S) strain, but the activity in the adults was 13-fold higher than in the larvae of the RM strain. To understand the effect of the application of a mixture of iprobenfos and malathion on the evolution of malathion resistance, an artificial strain (Syn) was generated by mixing the RM and S strains with 0.1 frequency of the malathion-resistant individuals. The offspring of the Syn strain were divided into two sub-strains, Rm and Rm+ibp, which were successively treated with, respectively, malathion alone and malathion + iprobenfos (1:2) at LC70. In the mixture, the fungicide iprobenfos acted as a synergist of malathion. After treatment for 10 generations, the resistance level to malathion was 317.4-fold for the Rm sub-strain, whereas for the Rm+ibp sub-strain it was only 38.9-fold, compared with the Syn strain. Similar results were obtained by measurement of alpha-NA esterase activity from both larvae and female adults. The alpha-NA esterase activities in larvae and female adults at F10 generation were 2.6- and 10.9-fold from the Rm+ibp sub-strain and 5.7- and 98.5-fold from the Rm sub-strain, respectively, compared with the Syn strain. The above results suggested that iprobenfos, although it cannot completely stop or prevent the onset of malathion resistance, could dramatically delay its evolution.

CYP6B2 Expression in Insecticide-Resistant and -Suspcitible Strains of Helicoverpa armigera.

A fragment of CYP6B2 gene was obtained from the midgut cDNA library of the fifth instar larvae of the ballworm (Helicoverpa armigera) with RT-PCR. The product of 627 bp was cloned and sequenced. The results of dot blotting analysis of mRNA proved that CYP6B2 is expressed at higher level (mRNA) in an insecticide-resistant strain than in a susceptible strain, showing that the regulation was at transcription level. The mRNA is induced by pyrethroid in susceptible, but not in the insecticide-resistant strains. We guess that mutation in the 5' upstream regulator of the insecticide-resistant strain may lead to the difference in the expression level between resistant and susceptible strains.