Comparison between the effects of Acetaminophen and Dexmedetomidine infusion and normal saline on pain severity after cataract surgery an open label randomized controlled trial

Comparison between the effects of Acetaminophen and Dexmedetomidine infusion on pain severity after cataract surgery under complete venous sedation

Three-arm parallel groups phase 3 randomized trial, single-blind, on 135 patients, sealedenvelope website was used for random allocation

All patients were monitored with electrocardiography, pulse oximetry, and non-invasive blood pressure monitoring. During the procedure, vital signs were recorded by a trained nurse in certain time-points. Pain intensity was evaluated and recorded based on Visual Analog Scale. Presence of nausea and vomiting after surgery was asked and recorded. The amount and time for the first narcotics request was recorded for each patient. side effects of medications and the satisfaction of ophthalmologists from the patient sedation during the operation was recorded. also, the length of stay in the recovery room was recorded. The study was performed at Feyz Ophthalmology Hospital in Isfahan.

Inclusion criteria: 1- A I or II physical health score according to the classification of the American Society of Anesthesiologists 2- Patient consent to participate in the study 3- age between 50 to 80 years old 4- being candidate for cataract surgery Exclusion criteria: 1- contraindication of dexmedetomidine or acetaminophen 2- Allergies to any of the drugs used in the trial 3- Blood coagulation problems 4- Altered mental status 5- Severe cardiovascular diseases 6- Chronic obstructive pulmonary disease

In group A, acetaminophen was infused at a dose of 15 mg/kg within the first 15 minutes of surgery. In group B, dexmedetomidine was infused at a dose of 0.5 µgr/kg within the first 15 minutes of surgery. In group C, only the infusion of normal saline was performed.

Pain severity; surgeon satisfaction

The study population was selected on a consecutive basis. For the randomization of the participants, first, the principal investigator used the “Sealedenvelope” website to create blocks containing 9 individuals, containing three participants for each of three groups. Every participant had a unique code consisting of two letters and one number. This generated list remained confidential for participants, clinicians who enrolled the patients in the study, clinicians who injected the drugs and data analyzer. Patients have entered the study groups (A, B and C) according to the generated list, after a full explanation of the study process and obtaining written consent.

This study is a single-blind study, where physicians and patients were aware of study groups and only the statistical analyzer was blind for treatment groups. Each group was assigned with A or B or C, which makes the analyzer blind for the treatment group.