Gomathi, M (2007) Comparative evaluation of classical subarachnoid block, unilateral subarachnoid block and low dose subarachnoid block in high risk patients undergoing lower limb surgeries. Masters thesis, Madras Medical College, Chennai.
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Abstract
INTRODUCTION: It was in the year 1899 August Bier, used subarachnoid block and he gave first deliberate spinal anaethesia. Spinal anesthesia continued to be most common anesthetic technique because of its rapid onset, safety and simplicity. Even this relatively safe technique can have complication such as hypotension which a normal patient can tolerate but can be detrimental to patients with haemodynamic instability. The safety improves if the block can be localized to the area of surgery. A special technique of spinal anaesthesia named spinal hemi block was described for one limb surgeries, which was named as spinal hemi analgesia. This is also known as unilateral spinal anaesthesia. The distance between the left and right spinal roots is only 10-15 millimeter in the lumbar or lower thoracic level. Such a small distance should reasonably prevent from producing strictly unilateral block of the spinal nerve roots. However, various clinical reports suggested that using small doses of either hypo or hyperbaric anesthetic solution injected at low speeds through directional needles in patients lying in the lateral decubitus position for 10-15 minutes results in preferential distribution of spinal anaesthesia towards the operated side, providing intense surgical block on that side. Even though the term unilateral spinal anaesthesia has been in vogue for a long time most of the research on this are recent. Even though performing spinal anaesthesia is technically easier, the complications which are usually expected like hypotension and bradycardia can be detrimental to this high risk group patients. AIM: To compare the efficacy of classical subarachnoid block using, 0.5% bupivacaine,unilateral spinal anesthesia using 0.5% bupivacaine and low dose spinal anesthesia using 0.5% bupivacaine 1.5 ml with 0.5 ml of fentanyl (25 micro grams) in high risk patients undergoing emergency unilateral lower limb surgeries based on the following parameters. 1. Feasibility of maintaining unilaterality of Subarachnoid block. 2. Haemodynamic stability in the peri-operative period. 3. Onset, Quality and duration of block. MATERIALS AND METHODS: The effect of lateral position on maintaining unilaterality of spinal anaesthesia and the effect of adding fentanyl to hyperbaric bupivacaine in achieving unilateral spinal anaethesia undergoing emergency lower limb surgeries on one limb was studied in 60 patients. The study was approved by the institutional research and ethics committee. The total number of patients are 60.They were divided into three groups. Control Group - Received 2ml of 0.5% Bupivacaine and turned to Supine position immediately. STUDY Group I - Received 1.5 ml of 0.5 % Bupivacaine with 25 μg( 0.5 ml) Fentanyl and kept in lateral decubitus position for 10 mints and then turned supine. STUDY Group II - Received 2ml of 0.5 % Bupivacaine and kept in lateral decubitus position for 10 mints and then turned supine. Inclusion Criteria: 1. Patients between 18 to 80 years of age. 2. Patients belonging to ASA physical status III and IV. 3. Undergoing emergency unilateral lower limb surgery. Exclusion Criteria: 1. All Contra indication for central neuraxial block. 2. Patients who are not co-operative to positioning for subarachnoid block. 3. Patients with anomalies of the spinal column SUMMARY: This prospective randomized study was done to compare the efficacy of classical subarachnoid block using 0.5% bupivacaine, unilateral spinal anesthesia using 0.5% bupivacaine and low dose spinal anesthesia using 0.5% bupivacaine 1.5 ml with 0.5 ml of fentanyl (25 micro grams) in sixty high risk patients undergoing emergency unilateral lower limb surgeries. This study yielded the following results: 1. Unilateral spinal anaesthesia can be produced by using small volume of hyperbaric local anaesthetic, slow injection of drugs and maintaining the patient in lateral position with the operated limb being dependant. 2. Unilateral spinal anaesthesia produces higher level of sensory block on dependant limb when compared to non-dependant limb. 3. Unilateral spinal anaesthesia produces higher level and greater degree of motor block on dependant when compared to non-dependant limb. 4. Unilateral spinal anaesthesia is more haemodynamically stable in high risk sick patients when compared to classical subarachnoid block. 5. Classical Subarachnoid block produces more haemodynamic complications (hypotension and bradycardia) which requires treatment. 6. Low dose Bupivacaine with Fentanyl subarachnoid block may lead to alteration in baricity / specific gravity of the solution. This however does not decrease the differential blockade between the two limbs. 7. The low dose Bupivacaine with Fentanyl Subarachnoid block is a more haemodynamically stable option in high risk patients. 8. The onset time and time for two space regression is not different among the three groups. 9. The biggest limitation to the production of unilateral subarachnoid block is the inability of the patients to lie in the lateral position for 10 minutes. 10.Time consideration for production of unilateral Subarachnoid block may be a restraining factor in emergency surgeries. The patient should be maintained strictly in lateral position with the limb to be operated kept dependant for at least 15 minutes to achieve unilateral block. CONCLUSION: From this study we can conclude that in high risk patients undergoing emergency unilateral lower limb surgeries. 1. Unilateral low dose Subarachnoid block offers better haemodynamic stability during the intra-operative period. 2. The onset, quality and duration of block matches those produced by classical subarachnoid block. 3. It is possible to produce unilateral subarachnoid block by maintaining patients in lateral position for 10 minutes.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Comparative evaluation ; classical subarachnoid block ; unilateral subarachnoid block ; low dose subarachnoid block ; high risk patients ; undergoing lower limb surgeries. |
| Subjects: | MEDICAL > Anaesthesiology |
| Depositing User: | Subramani R |
| Date Deposited: | 21 Apr 2018 06:33 |
| Last Modified: | 21 Apr 2018 06:33 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/7178 |
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