Bupivacaine is a local anesthetic that is largely used for spinal anesthesia, mainly as a hyperbaric or plain solution, Controversy exists regarding the predictability of the levels of analgesia achieved with isobaric bupivacaine solution when compared to hyperbaric bupivacaine.
Local anesthetics used for spinal anesthesia are mostly available as hyperbaric solutions and it is well established that the addition of dextrose to increase the specific gravity of the solutions alters the anesthetic profiles.
Position of the patient and baricity or density of the local anesthetic solution injected as determinants of distribution.
The sitting position is frequently used for induction of spinal anesthesia. Hyperbaric solutions, under the influence of gravity, would be expected to spread caudally whereas isobaric solutions would be expected to distribute rostrally.
This study aims to conduct a comprehensive comparative analysis between 0.5% bupivacaine heavy and 0.5% bupivacaine plain in elective infra umbilical abdominal surgeries, focusing on their respective duration of sensory and motor blockade,hemodynamic stability
AIMS AND OBJECTIVES
Comparing the clinical efficacy between hyperbaric 0.5% bupivacaine vs isobaric 0.5% bupivacaine during elective infra umblical abdominal surgeries.
Primary objective:
To compare the time of onset, the level and the duration of block obtained (both sensory and motor) between isobaric versus hyperbaric bupivacaine
Secondary objective:
To compare the effects of both the drugs on heamodynamic parameters (heart rate and blood pressure) and side effects
STUDY PROCEDURE:
Patients of undergoing elective infra umbilical abdominal surgeries planned under spinal anaesthesia who give written informed consent for the study, will be recruited and randomized based on a computer generated model.
After thorough clinical assessment and routine investigations , they will be randomly allocated into two groups containing 12 patients each. And for the purposes of the investigation will be unaware of the groups they will be allotted into.
Group A will receive spinal anesthesia using intrathecal 3ml 0.5% isobaric bupivacaine
Group B will receive spinal anesthesia using intrathecal 3ml 0.5% hyperbaric bupivacaine
On arrival in the anesthesia room the IV cannula will be secured. ECG , non invasive arterial pressure (SBP,DBP,MAP) and pulse oximetry will be monitored .Baseline values will be noted. patients were preloaded with 10 ml/kg of Ringer’s lactate over 10 min.
For blinding purposes, the primary anesthetist will be responsible for the randomization of the patients and the drug whereas the other investigator ( unaware of the group allocation and the drug administered) will be responsible for the induction of anesthesia as well as data collection.
After the injection of the spinal drug the assessments of sensory block will be done by pinprick test and Results of the pinprick test will be determined bilaterally at midclavicular level by using a short- beveled 27-gauge needle. Motor block in the lower limb was assessed by using a modified Bromage scale . These assessments will be performed immediately after the assessments of sensory block until the return of normal motor function.
After the injection of the spinal medication, heart rate and arterial blood pressure will be measured/recorded at 2min interval for first 10 minutes, 5min for the next 10 minutes and 10min intervals thereafter until 60 min post administration of drug.
In case of hypotension (systolic blood pressure (SBP) < 90 mmHg or a decrease in SBP BY 20% of the baseline value), will be managed by rapid infusion of 250 ml of Ringers lactate and 3 mg incremental doses of intra venous inj ephiderine . Similarly in case of bradycardia(HR<50 BPM) , will be managed with incremental doses of 0.3 mg intravenous atropine
The onset of sensory block is defined as the time taken for loss of sharp sensation with the pinprick test until the T8 dermatome level after injecting the drug (TT8 ).
The time of regression is defined as the time taken for regression of the block to two segments after injecting the drug was noted (Treg2 ).
The time taken to achieve ad equate motor block (TBrom2 ), defined as a score of 2 on the modified Bromage scale, was recorded by testing the motor block every minute until a score of 2 was achieved.
Surgery will be commenced once adequate sensory (T8) and motor (modified Bromage 2) block was achieved. The quality of surgical anesthesia was scored as follows depending on the pa tient’s response:
Excellent (Score 4): No complaint from the patient.
Satisfactory (Score 3): Patient allowed the surgery but sometimes complained of uneasiness, requiring supplemental analgesia with intravenous fentanyl (0.5 µg/kg bolus) maxi mum 4 µg/kg.
Inadequate (Score 2): Patient complained of pain and re quired conversion to general anesthesia.
Failure (Score 1): Adequate sensory level or motor block not achieved.
An incision will made once the sensory block of at least T6 level was achieved, along with motor block of modified Brom age grade 2 (10) or less. If these were not achieved in 20 min, it was considered failed spinal anesthesia and converted to general anesthesia.
The duration of anesthesia (Tanes ) is defined as the time interval between the onset of sensory block (T8 level) to regression of the sensory block to the L1 dermatome.
The duration of the motor block (TMB ) is defined as the time interval between the onset of motor block (modified Bromage scale 2) to the achievement of modified Bromage scale 6 after the surgery.
The time interval between administration of the subarachnoid block and the first request for supplemental analgesia by the patient will be noted as the duration of effective analgesia (Tanalg)