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This paper proposes an experimental modal analysis technique to measure the dynamic characteristics of microwave-casted metal matrix composite (MMC). To fabricate MMC, silicon carbide (SiC) is reinforced into the SS202 matrix. The damping capacities of MMC at different reinforcements of SiC powder such as 0.05%, 0.1% and 0.2% are measured through experimental modal analysis. The main objective is to study the effect of reinforcement on the damping capacity of SS202. The domestic microwave oven with the specification of 2.45 GHz and 900 W power is used to cast the MMC material. The graphite split mold is used for in-situ microwave casting. The mechanical characterization in terms of micro-hardness and scanning electron microscopy (SEM) of MMC is also examined. From SEM imagining, complete diffusion of the SiC in SS matrix is observed for 0.05% of SiC reinforcement; however, incomplete diffusion is observed for 0.1% and 0.2% of SiC reinforcement. It is observed that the hardness of the SS202 is increasing with the decrease in the percentage of SiC powder. The experimental modal analysis is carried out by using SO Analyzer. The response model in terms of the frequency response function (FRF) curve is measured when the specimen is excited at impact excitations. The half power bandwidth method is used to calculate the damping factor of the material from the measured FRFs. It is observed that the damping capacity increases with the increase in percentage of SiC in SS202. SS202 with 0.05%, 0.1% and 0.2% SiC have the hardness value of 155.33 HV, 107.33 HV and 58.33 HV, respectively.

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Background & Objective: Hyperbaric bupivacaine is the most commonly used local anesthetic for spinal anesthesia, alone or in combination with various adjuvants. Opioids are frequently used for their rapid onset and intense block characteristics. Fentanyl is the preferred intrathecal opioids with rapid onset of action but has a shorter duration of action. Buprenorphine is a mixed agonist-antagonist with high affinity at both mu and kappa opioid receptors. We compared administration of buprenorphine with fentanyl as adjuvants with intrathecal hyperbaric bupivacaine in gynecological surgeries. Methodology: After Institutional Ethical Committee approval and written informed consent, 60 patients aged 18–65 y, scheduled for lower abdominal gynecological surgery, were divided into two equal groups; Group F to receive 0.5% hyperbaric bupivacaine 2.5 ml with fentanyl 25 µg intrathecal and Group B to receive 0.5% hyperbaric bupivacaine 2.5 ml with buprenorphine 75 µg intrathecal. Block characteristics and associated side effects were compared between two groups. The data was analyzed using Chi square test and Fisher’s exact test. For comparing two group of mean, independent student’s t test was used. P-value < 0.05 was considered as statistically significant. Results: The mean onset of sensory and motor block was significantly earlier in Group F than Group B (p < 0.001). Mean duration of sensory block was significantly prolonged in Group B compared to Group F (p < 0.05). Whereas, the duration of motor was comparable in both of the groups (p > 0.05). Duration of analgesia was significantly prolonged in Group B than Group F (p < 0.001). Conclusion: We conclude that when a longer duration of postoperative pain relief is needed, buprenorphine can be a suitable drug to be used with intrathecal hyperbaric bupivacaine for gynecological surgeries because of prolonged duration of action. Key words: Spinal anesthesia; Fentanyl; Buprenorphine; Bupivacaine Citation: Singh Y, Yadav AK, Vijeta Bajpai, Diwedi P, Verma S, Verma RK. Comparison of intrathecal fentanyl and buprenorphine as adjuvants to bupivacaine in gynecological surgery. Anaesth. pain intensive care 2021;26(1):39-43. DOI: 10.35975/apic.v26i1.1764