Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2002
Randomized Controlled Trial Clinical TrialChloroprocaine is less painful than lidocaine for skin infiltration anesthesia.
Skin infiltration of local anesthetics causes pain. In a double-blinded protocol, 22 volunteers received random intradermal injections to the volar surface of the forearm with each of the following solutions: normal saline solution 0.9% (NSS), lidocaine 1% (L), lidocaine 1% and sodium bicarbonate 8.4% (L+BIC), 2-chloroprocaine 2% (CP), 2-chloroprocaine 2% and sodium bicarbonate 8.4% (CP+BIC), and NaCHO(3) 8.4% (BIC). Initially, each volunteer received an open-labeled injection of NSS. A 100-mm visual analog scale (VAS, 1-100) was used to assess pain with each injection. The pH of each solution was stable for the length of the study. Repeated measures of variance were used for analysis. The VAS scores (mean +/- SD) for open-label and blinded NSS injections were 15.5 +/- 15.9 and 14.0 +/- 18.1, respectively. The scores for the studied solutions were as follows: BIC, 47.2 +/- 25.5; L, 25.8 +/- 27.6; L+BIC, 16.0 +/- 14.2; CP, 8.6 +/- 7.4; and CP+BIC, 6.8 +/- 6.7. No significant difference was found between CP and alkalinized CP, but the injection of both solutions was significantly less painful than that of all other solutions (P < 0.05). The pH of the solutions was not related to the pain score. We found that chloroprocaine caused less pain at injection than the more commonly used lidocaine. ⋯ Using 2-chloroprocaine can diminish pain caused by the intradermal injection of lidocaine. pH variations of the solution did not relate to the pain profile of the local anesthetic.
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Anesthesia and analgesia · Feb 2002
Randomized Controlled Trial Clinical TrialThe effect of nitrous oxide on jugular bulb oxygen saturation during remifentanil plus target-controlled infusion propofol or sevoflurane in patients with brain tumors.
During propofol/fentanyl anesthesia, a large percentage of patients have jugular bulb oxygen saturation (SjO(2)) <50%. The incidence is less with isoflurane/N(2)O. We evaluated the effect of N(2)O on SjO(2) during remifentanil-based anesthesia with concurrent propofol or sevoflurane in 20 adults undergoing brain tumor surgery. Anesthesia was randomized: Group 1 (n = 10), target-controlled infusion propofol; and Group 2 (n = 10), thiopental 2-3 mg/kg followed by sevoflurane 0.9% end-tidal. Jugular bulb and arterial blood samples for gas analysis were withdrawn during the administration of oxygen 33% with nitrogen 67% and then with N(2)O 67%. All samples were drawn before surgery and 20 min after the addition of the study gas and with an ETCO(2) 26-28 mm Hg and mean arterial pressure >90 mm Hg. Both groups had similar demographic and physiologic data. In the Propofol group, SjO(2) was 50% +/- 10% with nitrogen and 52% +/- 9% with N(2)O (not significant); in the Sevoflurane group, however, N(2)O 67% increased SjO(2) from 56% +/- 13% to 66% +/- 12% (P < 0.01). This indicates that N(2)O does not reduce the incidence of low SjO(2) values during propofol anesthesia. ⋯ This study demonstrates that nitrous oxide can increase jugular bulb venous oxygen saturation when added to sevoflurane/remifentanil anesthesia, but not to propofol/remifentanil anesthesia, in patients with brain tumors.
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Anesthesia and analgesia · Feb 2002
Autoantibodies associated with volatile anesthetic hepatitis found in the sera of a large cohort of pediatric anesthesiologists.
Anesthetic-induced hepatitis is thought to have an immune-mediated basis, in part because many patients who develop hepatitis have serum autoantibodies that react with specific hepatic proteins. The present study shows that pediatric anesthesiologists also have these serum autoantibodies. Moreover, levels of these autoantibodies are higher than those of general anesthesiologists. We collected sera from 105 pediatric and 53 general anesthesiologists (including 3 nurse anesthetists), 20 halothane hepatitis patients, and 20 control individuals who were never exposed to inhaled anesthetics. Serum cytochrome P450 2E1 (P450 2E1) and 58-kd hepatic endoplasmic reticulum protein (ERp58) autoantibodies were measured by enzyme-linked immunosorbent assays. Positive values were 2 SD above median control values. Two multiple regression models were constructed. Pediatric anesthesiologists, like halothane hepatitis patients, had higher serum autoantibody levels of ERp58 and P450 2E1 than general anesthesiologists and controls, which was possibly because of their increased occupational exposures to anesthetics. Female anesthesiologists had higher levels of ERp58 autoantibodies than male anesthesiologists, whereas female pediatric anesthesiologists had higher levels of P450 2E1 autoantibodies than all other anesthesiologists. One female pediatric anesthesiologist had symptoms of hepatic injury. Because most anesthesiologists do not develop volatile anesthetic-induced hepatic injury, the findings suggest that pathogenic ERp58 and P450 2E1 autoantibodies may not directly cause volatile anesthetic hepatitis. Female anesthesiologists have high levels of these autoantibodies; however, the majority of these individuals do not develop hepatitis, suggesting that autoantibodies may not have a pathological role in volatile anesthetic-induced hepatitis. ⋯ Environmental exposure of anesthesiology personnel to certain inhaled anesthetics can induce the formation of autoantibodies that have been associated with anesthetic hepatitis. Female anesthesiologists have high levels of these autoantibodies; however, the majority of these individuals do not develop hepatitis, suggesting that autoantibodies may not have a pathological role in volatile anesthetic-induced hepatitis.
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Anesthesia and analgesia · Feb 2002
Venous air emboli occur during release of positive end-expiratory pressure and repositioning after sitting position surgery.
We studied the effect of positive end-expiratory pressure (PEEP) release and positioning on the occurrence of venous air embolism (VAE). Eighteen consecutive patients (8 women, 10 men; ASA grade I-III) undergoing neurosurgery in the sitting position were studied. After induction of anesthesia ventilation was controlled with a PEEP of 5 cm H(2)O in an oxygen-air gas mixture. A transesophageal echocardiographic (TEE) probe was inserted. Preoperatively, a patent foramen ovale was excluded in all patients. TEE monitoring was performed during surgery, during PEEP release at the end of surgery with the patient still in the sitting position, and during change of the patient position into the supine position. The severity of VAE was differentiated as follows: grade 1 = only microbubbles; grade 2 = microbubbles and decrease of end-tidal carbon dioxide partial pressure (PETCO(2)) by more than 1.5 mm Hg; grade 3 = microbubbles combined with a decrease of PETCO(2) by more than 1.5 mm Hg, and a decrease of mean arterial blood pressure by at least 20 mm Hg. During surgery, VAE with a grade of 1, 2 or 3 occurred in 7, 4, and 2 patients, respectively. After PEEP release, VAE of grades 1, 2, and 3 were observed in 7, 2, and 1 patients, respectively. During repositioning from sitting to supine position, VAE of grades 1, 2, and 3 was observed in 6, 1, and 1 patients, respectively. The patient with VAE grade 3 needed inotropic support until 2 h after surgery to maintain sufficient blood pressure. No patient showed any sign of paradoxical arterial embolism or cardiac dysfunction. We conclude that VAE occurs not only during surgery in the sitting position, but also with release of PEEP and during repositioning to the supine position. ⋯ This study shows that venous air embolism (VAE) occurs not only during surgery in the sitting position but also during positive end-expiratory pressure release and repositioning of the patient into the supine position. Continuous monitoring for VAE should be performed until the patient is returned to the supine position.
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Anesthesia and analgesia · Feb 2002
An evaluation of the cutaneous distribution after obturator nerve block.
In 1973, Winnie et al. introduced the inguinal paravascular three-in-one block, which allegedly provides anesthesia of three nerves--the femoral, lateral cutaneous femoral, and obturator nerves--with a single injection. This concept was undisputed until the success of the obturator nerve block was reassessed by using evidence of adductor weakness rather than cutaneous sensory blockade, the latter being variable in its distribution and often absent. We performed this study, therefore, to evaluate the area of sensory loss produced by direct injection of local anesthetic around the obturator nerve. A selective obturator nerve block with 7 mL of 0.75% ropivacaine was performed in 30 patients scheduled for knee surgery. Sensory deficit and adductor strength were evaluated for 30 min by using sensory tests (cold and light-touch perception) and the pressure generated by the patient's squeezing a blood pressure cuff placed between the knees. Subsequently, a three-in-one block was performed, and the sensory deficit was reassessed. The obturator nerve block was successful in 100% of cases. The strength of adductors decreased by 77% +/- 17% (mean +/- SD). In 17 patients (57%), there was no cutaneous contribution of the obturator nerve. The remaining 7 patients (23%) had an area of hypoesthesia (cold sensation was blunt but still present) on the superior part of the popliteal fossa, and the other 6 (20%) had sensory deficit located at the medial aspect of the thigh. The three-in-one block resulted in blockade of the lateral aspect of the thigh in 87% of cases, whereas the anteromedial aspect was always anesthetized. By use of magnetic resonance imaging in eight volunteers, we demonstrated that the obturator nerve has already divided into its two branches at the site of local anesthetic injection. However, the injection of blue dye after having simulated the technique in five cadavers showed that the fluid regularly spread to both branches. We conclude that after three-in-one block, a femoral nerve block may have been assessed as an obturator nerve block in 100% of cases when testing the cutaneous distribution of the obturator nerve on the medial aspect of the thigh. ⋯ Previous studies reporting an incidence of obturator nerve block after three-in-one block may have mistaken a femoral nerve block for an obturator nerve block in 100% of cases when the cutaneous distribution of the obturator nerve was assessed on the medial aspect of the thigh. The only way to effectively evaluate obturator nerve function is to assess adductor strength.