A cadaveric study about the localization of sciatic nerve separation point in Thais: Implications for nerve block.

Objectives: The aim of this study was to evaluate the distance of the separation point of sciatic nerve in popliteal fossa and its relation to the length of femur in Thai cadavers. Method: One hundred and six Thai cadavers which composed of 105 right legs and 106 left legs were examined in this study. After dissection of the popliteal fossa, the distance of the separation point of the sciatic nerve above the level of both femoral epicondyles was measured in 84 right legs and 89 left legs of 66 male and 40 female cadavers. In addition the length of femur, which was the distance from posterior edge of the greater trochanter to the most prominent point of lateral epicondyles, was recorded. Results: In the specimen of this study, the sciatic nerves separated at a mean distance of 8.72 + 4.35 cm and 7.32 + 3.03 cm above the level of both femoral epicondyles in male and female cadavers with the highly variation range from 2.1 to 30.7 cm. The mean distances of the right and left legs in male cadavers were 8.49 + 4.39 and 8.90 + 4.32 cm respectively, being longer than in female cadavers (7.32 + 3.67 and 7.28 + 2.30 cm respectively) There were no significant differences in both the distance of the separation point and the length of femur by sex or side. Conclusion: The distances of the separation point of the sciatic nerve above the level of both epicondyles in Thai cadavers were highly variable and not related with the length of the femur.

Factors affecting delayed extubation after intracranial surgery in Siriraj Hospital.

Background: The time to extubation in neurosurgical patients depends on a number of various factors, including patient, surgical and anesthetic factors. Objective: To determine the factors influencing the time to extubation in neurosurgical patients. Methods: This study is a prospective study including all patients who underwent intracranial surgery from October 2008 to April 2009 at Siriraj Hospital. We excluded patients who were under the age of 18 years, intubated or had undergone tracheostomy prior to the surgery and had a history of difficult intubation. Demographic data and various factors expected to involve the extubation were collected and analyzed. Results: There were 171 (89.1%) patients suitable for the early extubation and 21 (10.9%) patients remained in the intubated condition. A univariate analysis revealed 10 factors influencing failure of the extubation, including age >65 years, ASA physical status > class II, Glasgow coma score (GCS) <13, emergency surgical condition, anesthetic time >300 minutes, estimated blood loss >700 ml, use of cerebral protective technique, total propofol dosage >1,000 mg, total fentanyl dosage >50 mcg/hour, and a completed operation time after 4 pm. In a multivariate analysis, the delayed extubation was associated with 3 factors, including GCS <13, emergency surgical condition and estimated blood loss >700 ml. Conclusion: The incidence of the early extubation in neurosurgical patients who underwent intracranial surgery was 89.1%. Factors associated with an increased risk of delayed extubation included low Glasgow coma score, emergency surgical status and a large amount of intra-operative blood loss.

Lower interscalene approach, the novel landmark for more success rate of supraclavicular block: a comparison with the classical approach in fresh cadavers.

Objective: To create a novel landmark for supraclavicular block, the lower interscalene approach, to increase its success rate. Methods: A prospective study was performed and carried out at the Department of Forensic Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University. Both the lower interscalene approach and the classical approach were tested by simulating the supraclavicular block in forty fresh cadavers. Each approach was randomly done on each side of the same body. To determine the accuracy of the needle tip encroachment on the epineurium, staining of methylene blue on the nerves was defined as the success of the nerve localization. The localization of methylene blue was observed and the correlation between the success rates of the dye stained on the nerve trunk and the length of the patient’s neck was analyzed. Results: The success rate of three - nerve - trunk localization was 62.5 % by the lower interscalene approach, compared with 40 % by the classical approach (p value = 0.037). The success rates of superior, medial and inferior nerve trunk localization in the lower interscalene group were 70.0 %, 92.5 % and 97.5 %, compared with 67.5 %, 87.5 % and 65.0 % in the classical group, respectively. Their p values were 0.5, 0.355 and 0.001 respectively. There was neither correlation between the succsess rate of nerve localization and the clavicle length nor the neck length, but there was significant correlation between the success rate of three - nerve - trunk localization and the needle insertion depth in the classical group (p value = 0.031). Conclusion: Compared with the classical approach, the lower interscalene approach obtained more spreading of methylene blue on the brachial plexus as well as on the inferior nerve trunk. The authors therefore recommend the lower interscalene approach as the novel landmark for more success of supraclavicular block.