Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2004
Comparative StudyInsulin decreases isoflurane minimum alveolar anesthetic concentration in rats independently of an effect on the spinal cord.
The observation that insulin supplies an element of analgesia suggests that insulin administration might decrease the concentration of inhaled anesthetic required to produce MAC (the minimum alveolar anesthetic concentration required to eliminate movement in response to noxious stimulation in 50% of subjects). We hypothesized that insulin decreases MAC by directly affecting the nervous system, by decreasing blood glucose, or both. To test these hypotheses, we infused increasing doses of insulin either intrathecally or IV in rats anesthetized with isoflurane and determined the resulting MAC change (assessing forelimb and hindlimb movement separately). Infusion of insulin produced a dose-related decrease in MAC that did not differ among groups. That is, the IV and intrathecal infusions caused similar decreases in MAC at a given infusion rate. Blood glucose concentrations were larger in the rats given insulin with 5% dextrose. However, the percentage change in MAC determined from forelimb versus hindlimb movement did not differ. For a given insulin infusion rate, MAC changes and glucose levels did not correlate with each other, except, possibly, for the most rapid infusion rate, for which smaller glucose concentrations were associated with a marginally larger decrease in MAC. Intrathecal infusions of insulin did not produce spinal cord injury. In summary, we found that insulin decreases isoflurane MAC in a dose-related manner independently of its effects on the blood concentration of glucose. The sites at which insulin acts to decrease MAC appear to be supraspinal rather than spinal. The effect may be due to a capacity of insulin to produce analgesia through an action on one or more neurotransmitter receptors. ⋯ Intrathecal and IV insulin administration equally decrease isoflurane MAC in rats, regardless of the concentration of blood sugar. These findings indicate that although insulin decreases MAC, the decrease is not mediated by actions on the spinal cord.
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Anesthesia and analgesia · Jun 2004
Case ReportsPerioperative pain management of a complex orthopedic surgical procedure with double continuous nerve blocks in a burned child.
The use of catheters for continuous nerve blocks has been established in children, although in most series only one catheter was used. We report a case of a 3-yr-old child who underwent a toe-to-finger transfer managed with 2 regional catheters: axillary and sciatic. A pain score of 0 was noted during the entire study period. The total dose of bupivacaine was limited to an acceptable range, and the child recovered completely. This report adds to growing evidence in favor of the safety and efficacy of continuous peripheral nerve blocks in pediatric patients. ⋯ Double continuous nerve blocks allow optimal analgesia in burned children after complex orthopedic surgery without major adverse events. Plasma concentrations of bupivacaine remained small during the study period.
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Anesthesia and analgesia · Jun 2004
Case ReportsChange in bispectral index during epileptiform electrical activity under sevoflurane anesthesia in a patient with epilepsy.
We observed abnormal fluctuation in Bispectral Index (BIS) caused by repeated alternations between two electroencephalographic (EEG) waveform patterns in a patient with a recent history of epileptic seizure under sevoflurane anesthesia. The repetitive development of the abnormal EEG changes (slow delta with or without spike) and the fluctuation in BIS disappeared almost immediately after administration of anticonvulsants. BIS may give useful information not only on the sedative-hypnotic state, but also on the development of and recovery from abnormal epileptiform EEG activity. ⋯ During epileptiform electroencephalographic activity (EEG), the Bispectral Index shows an abnormal fluctuation caused by repeated abrupt alterations between normal EEG and abnormal epileptiform EEG patterns.
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Anesthesia and analgesia · Jun 2004
Case ReportsA severe complication after laser-induced damage to a transtracheal catheter during endoscopic laryngeal microsurgery.
Subcutaneous emphysema and pneumothorax is a rare and severe complication of percutaneous transtracheal jet ventilation, usually caused by obstruction of the upper airway or displacement of the tracheal catheter. Nevertheless, it is our preferred technique for endoscopic laryngeal laser surgery. We report a patient with acute subcutaneous emphysema and pneumothorax during laser surgery, caused by unobserved laser damage and discuss the associated risk factors. ⋯ The percutaneous transtracheal jet ventilation for elective laryngeal laser surgery reduces the risk of airway fires and gives a free endoscopic operative field. This case report suggests that, even when using a teflon catheter, laser-induced damage with severe complications might occur.
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Anesthesia and analgesia · Jun 2004
Anterior approach to the sciatic nerve block: adaptation to the patient's height.
To improve the incidence of block of the posterior femoral cutaneous nerve (PFCN) when using an anterior approach as described recently, we hypothesized that the distance between the inguinal line and the puncture site depends on the patient's height. A preliminary radiological study performed in 13 patients established a formula describing the relationships between the patient's height and the puncture site "S." A line was drawn between the anterior iliac spine and the superior angle of the pubic tubercle (inguinal line) and another line from the midpoint of the inguinal line to the puncture site "S." "S" was calculated from the midpoint of the inguinal line as "S" = (height in cm--100)/10. A prospective study was conducted in 53 patients. Results are presented as median (range, 0.25-0.75). Two minutes were required to locate the sciatic nerve at a depth of 12 cm (10.5-13.0 cm). Complete sciatic and PFCN blocks were observed in 92% of the patients. We conclude that consideration should be given to the patient's height when the sciatic nerve is blocked using an anterior approach. This technique seems to improve the success of block of the PFCN, essential to tolerate a thigh tourniquet. ⋯ This prospective but noncomparative work was performed to evaluate a new anterior technique of sciatic block, an adaptation of the anatomic landmarks described by Chelly and Delaunay, to patient height.