Efficacy of Fentanyl to Reduce the Time of Severe Postoperative Pain Relief Compared to Morphine

The nurse will administer 1 ug per kg during 5 seconds when the patient complain of pain (visual analog scale, VAS, ≥7). Immediately with the onset of drug administration a timer started; every 5 minutes the researcher assess the EVA and the drug will be administered if VAS \> 3, until the patient manifests as a lower pain VAS ≤ 3 (mild). The nurse in charge in the PACU will manage the drug and will take 100 ug of fentanyl which is diluted in 10 mL of normal saline leaving a 10μg per ml concentration, are not labeled and for the physical and chemical characteristics of both drugs (colorless) risks of unblinded is minimized.

The nurse will administer 0,1 mg per kg during 5 seconds when the patient complain of pain (visual analog scale, VAS, ≥7). Immediately with the onset of drug administration a timer started; every 5 minutes the researcher assess the EVA and the drug will be administered if VAS \> 3, until the patient manifests as a lower pain VAS ≤ 3 (mild). The nurse in charge in the PACU will manage the drug and will take 10 mg of morphine which is diluted in 10 mL of normal saline leaving a 1 mg per ml concentration, are not labeled and for the physical and chemical characteristics of both drugs (colorless) risks of unblinded is minimized.