Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2002
Ultrasound guidance for the psoas compartment block: an imaging study.
We conducted this study to develop an ultrasound-guided approach to the psoas compartment and to assess its feasibility and accuracy by means of computed tomography (CT). Two examiners performed ultrasound-guided approaches at three levels (L2-3, L3-4, and L4-5) on 10 embalmed cadavers, which were seated prone. After each needle had been advanced into the psoas compartment under ultrasound guidance, the positions of their tips were computed by using two coordinates (A and B). Subsequently, axial transverse CT scans were made to verify the ultrasound measurements by using the same coordinates. In total, 48 approaches were performed (Examiner 1, n = 20; Examiner 2, n = 28). CT revealed that 47 of 48 ultrasound-guided approaches were performed exactly. In 1 of 48 approaches (L3-4), the tip of the needle was located posterior to the psoas muscle. The median differences between ultrasound and CT coordinates were 0.3 plus minus 0.3 cm for A and 0.2 plus minus 0.3 for B. Kendall's coefficient of concordance was 0.9 (P < 0.001) between ultrasound and CT measurements for both coordinates. These results indicate that ultrasound enables exact needle placement, as proved by CT. We conclude that ultrasound guidance might be a useful adjunct to increase the safety and efficacy of the psoas compartment block at these levels. ⋯ We developed an ultrasound-guided approach to the psoas compartment at the levels L2-3, L3-4, and L4-5. Feasibility and accuracy were tested on embalmed cadavers and verified by means of computed tomography. Ultrasound guidance proved to be feasible and accurate for the performance of psoas compartment blocks.
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Drugs affecting bacterial growth may influence the occurrence of postoperative infections. Ropivacaine 10 mg/mL killed Staphylococcus aureus and Escherichia coli; ropivacaine 2 mg/mL supported the growth of E. coli.
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Anesthesia and analgesia · Mar 2002
The antinociceptive and histologic effect of sciatic nerve blocks with 5% butamben suspension in rats.
Butamben, a lipophilic local anesthetic of the ester class, produces a differential nerve block of long duration. Epidural and peripheral nerve blocks with butamben, formulated as a 5%--10% suspension, result in prolonged analgesia without significant motor blockade. We evaluated the effect of butamben sciatic nerve block on antinociception using the rat paw formalin test, as well as withdrawal latencies to thermal stimulation, and assessed histologic changes in the nerve. After right sciatic nerve block with butamben 5% or saline, responses to intradermal injection of 5% formalin were recorded in randomly selected groups of 6 animals each on days 1, 2, 5, 10, 21, and 28. In an additional group of 8 thermal challenges to both hind paws were recorded at 1, 2, 5, 7, 10, 14, 17, 21, and 28 days after right sciatic butamben 5% blocks. Butamben injection decreased the formalin-induced flinches on days 2, 5, 10, 21 and 28 and decreased thermal challenges on days 1 through 17. Histologic changes were minimal. This study demonstrates a prolonged antinociceptive effect from butamben nerve block to both formalin-induced nociception and heat hyperalgesia, without an effect on gross motor function or histologic morphology. ⋯ Butamben 5% nerve blocks produced a prolonged antinociceptive effect to formalin-induced nociception and heat hyperalgesia, without significant motor effect or evidence of substantial histologic changes.
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Anesthesia and analgesia · Mar 2002
The effect of universal leukodepletion of packed red blood cells on postoperative infections in high-risk patients undergoing abdominal aortic surgery.
We evaluated, by using a before-and-after study, the influence of leukoreduction by filtration on postoperative infections and adverse outcomes in patients undergoing elective major aortic surgery. From January 1995 to October 2000, all patients who underwent elective abdominal aortic surgery were included in the analysis. Before the introduction of systematic leukodepletion of packed red blood cells (RBCs), on April 1, 1998, 192 patients received standard or buffy-coat-depleted packed RBCs. Then, 195 patients were transfused with exclusively filtered leukodepleted packed RBCs. No major significant difference was observed between the groups of patients with regard to preoperative cardiac and pulmonary status, anesthetic and surgical techniques, or transfusion policy. No significant difference in mortality was observed between the two groups. The incidence of postoperative infections was 31% (95% confidence interval, 25%--38%) in the Control group versus 27% (95% confidence interval, 21%--33%) in the Leukodepleted group; severe infectious complications and pneumonia were not significantly different between the two groups of patients. Cardiovascular and respiratory outcomes were not significantly different between the groups. Data from this study suggest that the effect of using leukodepleted RBC on postoperative infections is not of obvious importance. ⋯ We evaluated the influence of leukocyte reduction by filtration of packed red blood cells (RBC) on postoperative infections and adverse outcomes in patients undergoing elective major aortic surgery by comparing two epochs with and without filtration. Data from this study suggest that the effect of using filtered RBC on postoperative infections is not of obvious importance.
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Anesthesia and analgesia · Mar 2002
The effects of low-pressure carbon dioxide pneumoperitoneum on cerebral oxygenation and cerebral blood volume in children.
We examined the effects of low-pressure carbon dioxide pneumoperitoneum on regional cerebral oxygen saturation (ScO(2)) and cerebral blood volume (CBV) in children. Fifteen children, ASA I--III, scheduled for laparoscopic fundoplication, were investigated in the head-up position (10) and ventilated to a baseline end-tidal CO(2) (PETCO(2)) between 25 and 33 mm Hg. Ventilatory settings remained unchanged during the operation. ScO(2) and CBV were assessed with near-infrared spectroscopy and recorded together with end-tidal and arterial carbon dioxide (PaCO(2)) at 5 time points: before insufflation, 30, 60, and 90 min after the start of CO(2) insufflation, and 10 min after desufflation. The intraabdominal pressure was kept between 5 and 8 mm Hg. During insufflation, PETCO(2) increased from 30.0 plus minus 2.8 to 38.3 plus minus 5.1 mm Hg (P < 0.001) and PaCO(2) increased from 32.0 plus minus 4.7 to 40.4 plus minus 5.9 mm Hg (P < 0.001). ScO(2) increased by 15.7% plus minus 8.8% (from 61 plus minus 9 to 70 plus minus 9 arbitrary units ) (P < 0.001). CBV increased by 4.6% plus minus 8.8% (from 123 plus minus 66 to 128 plus minus 66 arbitrary units [P = 0.048]). After desufflation, PETCO(2) and PaCO(2) decreased, but did not return to preinsufflation values. ScO(2) and CBV also decreased after desufflation. In conclusion, hyperventilation and the head-up position before CO(2) insufflation are not sufficient to prevent the CO(2)-mediated cerebral hemodynamic effects of low-pressure pneumoperitoneum (5--8 mm Hg) in children. ⋯ Peritoneal CO(2) absorption during laparoscopic surgery causes hypercapnia and CO(2)-mediated cerebral hemodynamic effects. Hyperventilation and the head-up position before CO(2) insufflation is not sufficient to counteract these effects of low-pressure pneumoperitoneum (5--8 mm Hg) in children.