Effects of Intraoperative Opioid Administration on Postoperative Pain and Pain Threshold: A Randomized Controlled Study.

Fentanyl and short-acting remifentanil are often used in combination. We evaluated the effect of intraoperative opioid administration on postoperative pain and pain thresholds when the two drugs were used. Patients who underwent gynecological laparoscopic surgery were randomly assigned into two groups (15 patients each) to receive either sufficient (group A) or minimum (group B) fentanyl (maximum estimated effect site concentration: A: 7.86 ng/mL, B: 1.5 ng/mL). The estimated effect site concentration at the end of surgery was adjusted to the same level (1 ng/mL). Patients in both groups also received continuous intravenous remifentanil during surgery. The primary outcome was the pressure pain threshold, as evaluated by a pressure algometer 3 h postoperatively. The pressure pain threshold at 3 h postoperatively was 51.1% (95% CI: [44.4-57.8]) in group A and 56.6% [49.5-63.6] in group B, assuming a preoperative value of 100% (p = 0.298). There were no significant differences in pressure pain threshold and numeric rating scale scores between the groups after surgery. The pain threshold decreased significantly in both groups at 3 h postoperatively compared to preoperative values, and recovered at 24 h. Co-administration of both opioids caused hyperalgesia regardless of fentanyl dose.

Selective Spectrophotometric Determination of Trace Amounts of Cadmium in Soil and Sediment Samples Using a Green Aqueous Biphasic Extraction.

A green extraction spectrophotometric method was presented for the determination of trace amounts of cadmium in soil and sediment samples. This method is based on the selective extraction of cadmium as its iodide complex by aqueous biphasic extraction composed of polyethylene glycol (PEG) and sodium sulfate, and a subsequent sensitive determination by spectrophotometry using 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol. This extraction method is simple and environmentally benign, since the organic solvents used for the traditional liquid-liquid extractions are replaced by the non-toxic polymer and inorganic salt. Cadmium can be selectively extracted from soil and sediment samples into the PEG-rich upper phase by an aqueous biphasic system containing potassium iodide and sulfuric acid. The proposed method was applied to the determination of cadmium in certified reference materials for soil and river sediment. The obtained results were in good agreement with the certified values.