Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2002
Clinical TrialThe anatomic relationship of the sciatic nerve to the lesser trochanter: implications for anterior sciatic nerve block.
Classic descriptions of the anterior sciatic nerve block suggest needle placement at the level of the lesser trochanter of the femur. Recently, investigators have reported that the sciatic nerve is not accessible at this level. To define more accurately the anatomic relationship of the sciatic nerve to the lesser trochanter, we analyzed magnetic resonance scans performed on 20 patients in the supine position. After IRB approval, magnetic resonance scans of the hip and proximal femur were reviewed in 20 supine patients in the neutral position. Images from five axial levels were studied, specifically, at the level of the lesser trochanter and at 1-cm intervals inferior to the lesser trochanter for 4 cm. In each axial image, the medial or lateral distance was measured from the sciatic nerve to a sagittal plane at the medial border of the femur. If the sciatic nerve was lateral to this sagittal plane (inaccessible), the distance was assigned a negative value, and if the sciatic nerve was medial to the sagittal plane (accessible), the distance was assigned a positive value. The distance between the coronal plane at the anterior border of the femur and the coronal plane through the sciatic nerve was also recorded for each level. At the level of the lesser trochanter, the sciatic nerve was lateral to the femoral border (inaccessible) in 13 of 20 patients with a mean distance of -4.0 +/- 7.7 mm. At 4 cm below the lesser trochanter, the sciatic nerve was medial to the femoral border (accessible) in 19 of 20 patients with a mean distance 7.8 +/- 5.8 mm. The distance from the anterior border of the femur to the sciatic nerve was 42.9 +/- 5.8 mm at the level of the lesser trochanter and 45.7 +/- 9.5 mm at 4 cm below the lesser trochanter. The classic description of the anterior approach to the sciatic nerve suggests that the needle be walked off medially at the level of the lesser trochanter. Our data are consistent with recent reports suggesting that in the majority of subjects, the position of the sciatic nerve relative to lesser trochanter made it inaccessible from an anterior approach at this level. In contrast, at 4 cm below the lesser trochanter, the sciatic nerve was medial to the femur in 19 of 20 subjects. We conclude that needle insertion medial to the proximal femur, 4 cm below the lesser trochanter, is a more direct anatomical approach to the anterior sciatic nerve block. ⋯ Magnetic resonance images suggest that in the majority of supine subjects, the sciatic nerve is lateral to the lesser trochanter of the femur and therefore not accessible using the classic anterior approach. By contrast, 4 cm below the lesser trochanter, the sciatic nerve is consistently medial to the femoral shaft and therefore may be more accessible using an anterior approach.
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Anesthesia and analgesia · Oct 2002
Hypertonic-hyperoncotic solutions reduce the release of cardiac troponin I and s-100 after successful cardiopulmonary resuscitation in pigs.
In some patients, cardiopulmonary resuscitation (CPR) can revive spontaneous circulation (ROSC). However, neurological outcome often remains poor. Hypertonic-hyperoncotic solutions (HHS) have been shown to improve microvascular conductivity after regional and global ischemia. We investigated the effect of infusion of HHS in a porcine CPR model. Cardiac arrest was induced by ventricular fibrillation. Advanced cardiac life support was begun after 4 min of nonintervention and 1 min of basic life support. Upon ROSC, the animals randomly received 125 mL of either normal saline (placebo, n = 8) or 7.2% NaCl and 10% hydroxyethyl starch 200,000/0.5 (HHS, n = 7). Myocardial and cerebral damage were assessed by serum concentrations of cardiac troponin I and astroglial protein S-100, respectively, up to 240 min after ROSC. In all animals, the levels of cardiac troponin I and S-100 increased after ROSC (P < 0.01). This increase was significantly blunted in animals that received HHS instead of placebo. The use of HHS in the setting of CPR may provide a new option in reducing cell damage in postischemic myocardial and cerebral tissues. ⋯ Infusion of hypertonic-hyperoncotic solutions (HHS) after successful cardiopulmonary resuscitation in pigs significantly reduced the release of cardiac troponin I and cerebral protein S-100, which are sensitive and specific markers of cell damage. Treatment with HHS may provide a new option to improve the outcome of cardiopulmonary resuscitation.
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Anesthesia and analgesia · Oct 2002
A retrospective analysis of the costs and benefits related to alterations in cardiac surgery from routine intraoperative transesophageal echocardiography.
We sought to determine how frequently intraoperative transesophageal echocardiography (TEE) altered the planned surgical procedure and to assess the potential cost implications associated with these changes. A retrospective chart review was conducted at one university hospital. Cardiac surgical operative notes from July 1999 through June 2000 were reviewed. We interrogated all adult cardiac surgical records for patients scheduled for repair of coronary artery disease or valvular disease requiring the use of cardiopulmonary bypass. Cancellations based on TEE findings were included in the analysis. Of the 430 patient records reviewed, 24 procedures were ether canceled or changed on the basis of the intraoperative TEE examination (5.6%; 95% confidence interval, 3.6%-8.2%). Six of these cases involved valvular heart disease, and the remaining 18 involved the intraoperative diagnosis and repair of a patent foramen ovale. A cost-benefit analysis based on the 6 valvular diagnoses revealed a saving of $230 per patient. Assuming that unnecessary present or future operations may be avoided by altering the surgical plan on the basis of TEE findings, these preliminary data suggest that routine intraoperative TEE in cardiac surgery is beneficial and cost-effective. ⋯ A review of 430 adult cardiac surgical records indicates that routine transesophageal echocardiography during cardiac surgery, including coronary artery surgery, is beneficial and cost-effective.
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Anesthesia and analgesia · Oct 2002
Case ReportsLaryngeal trauma during awake fiberoptic intubation.
We describe three patients with difficult airways in which fiberoptic endotracheal intubation was used to insert breathing tubes into the patients' windpipes. Airway injury occurred during the use of this technique. Although largely a safe technique, care should be exercised when anesthesiologists choose equipment and when they perform this technique.
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Anesthesia and analgesia · Oct 2002
Case ReportsDissociative mental state in a patient with an intrathecal drug administration system.
We describe a patient with acute mental status changes, which resolved on removal of medication from the reservoir of a Synchromed intrathecal pump. This report highlights the potential adverse mental affects of chronic spinal infusions for pain therapy and discusses pitfalls in toxicology analysis using immunoassay.