Assesment the effect of intravenous injection site on the quality of intravenous regional anesthesia (bier block) on upper limb: a double-blinded randomize clinical trial

Background: Bier block is a reliable technique used in extremity surgeries. Typically, angiocatheters are palced in the distal portion of the extremity that is going to be operated. Although, it is not the case in every operation. Therefore, determining the effectiveness of the local anesthetic injection site on the quality of the upper-extremity block can be helpful. Methods: In this double-blinded randomized clinical trial that took place in Kowsar Hospital (Sanandaj, Iran) at 2020, 60 patients after complete monitoring and sedation were assigned randomly into proximal bier block (32 in experimental) and distal bier block (28 in control) groups. 10ml/kg Ringer serum was prescribed for patients in both groups on the non-surgical hand. Depending on the patients’ placement in either group, an angiocatheter (22 or 24) was attached to the ante-cubital area (proximal bier block group) or on the back of the patient's hand (distal bier block group). Respectively, after blood was drained by a Smarch band from the extremity that was to be operated, the tourniquet was inflated up to 150mmHg above the patient’s systolic pressure and the smarch band is untied from the hand. For every patient regarding the group they were assigned, 3mg/kg lidocaine 0.5% was administered through an angiocatheter. After 5 minutes, the depth of patient's anesthesia and pain intensity were measured. Sensory and motor recovery was assessed every 10 minutes after surgery. Patient satisfaction with anesthesia was measured after the surgery and characterized by excellent, good, moderate (pain relief), and unsuccessful (need for pain medications) indicators. In case insufficient depth was reached, intravenous Remifentanil was injected. Results: According to the results of the chi-squared test, there were no significant differences in gender distribution (p=0.063), anesthesia class type (p=0.964), type of surgery (p=0.694), anesthesia satisfaction (p=0.578), sensory block of hand (p=0.529), motor block of hand (p=0.059), pain intensity (p= 0.634), pain relief medication requesting (p=0.755) and also body mass index (T-test used P=0.099) variables comparing both groups together. Additionally; according to the T-test results no significant differences were reported in the mean systolic pressure, mean diastolic pressure and mean heart rate variable in designated times. Conclusion: There is no significant difference between the two groups. Therefore, using a distal Bier block can be an alternative if needed.