Effect of injection speed of heavy bupivacaine in spinal anaesthesia on hemodynamic changes and quality of block

1.  After approval from the Institutional Ethics Committee, the study participants will be given the patient information sheet and will be explained about the procedure before obtaining a valid, written consent. The consenting patients will be receiving spinal anesthesia drug at the speed which will be at discretion of consultant anesthesiologist and the effect of different drug speeds will only be observed and compared.

2. The selection of drug speed is at the discretion of consultant anesthesiologist and it is as per routine standard of care.

3. Patients will be premedicated with alprazolam 0.25 mg orally on the night before the surgery as well as pantoprazole 40 mg and metoclopramide 10 mg orally on the night before and on the morning of surgery.

4. The patient will be shifted to the operation theater, after confirming the nil per oral status. In the operation theatre, electrocardiogram, pulse oximetry and non invasive blood pressure monitors will be attached. The patency of the intravenous cannula will be checked and an intravenous access will be secured if none.

5. Baseline heart rate and blood pressure will be recorded. Patients will be then given 10 mL/kg of lactated Ringer’s solution.

6. Patients will be positioned in the lateral decubitus position. Under strict aseptic precautions and using midline approach, dural puncture will be done at the L3-L4 interspace with 25 G Quincke Babcock needle. After confirmation of free flow of CSF, 3.2 mL of spinal drug ( 3ml of 0.5% hyperbaric bupivacaine + 60 mcg buprenorphine) will be administered.

7. The patients will then be turned into supine position and data will be collected. Sensory block will be assessed by loss of cold sensation using cold alcohol swab.

8. Mean arterial pressure (MAP) ( hypotension will be defined as MAP less than 25% of patient’s baseline MAP value) and HR will be measured at 2 minute intervals for the first 10 minutes and 5 minute interval thereafter for 1 hour following the spinal injection.

9. The time to achieve maximum desired sensory blockade will be recorded. A modified Bromage score will be used for evaluation of the degree of motor block – Grade 1: Free movement of legs and feet implied no motor block, Grade 2: Just able to flex knees with free movement of feet implied partial (33%) block, Grade 3: Unable to flex knees but free movement of feet implied (66%) partial block, and Grade 4: Unable to move legs or feet implied complete paralysis.

10. Surgery will be allowed to proceed after desired dermatomal blockade is achieved

11. If desired dermatomal blockade is not achieved, then general anesthesia will be administered to the patient and then that patient will no longer be a part of this study.