Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2002
Flumazenil recovers diaphragm muscle dysfunction caused by midazolam in dogs.
We studied the effects of flumazenil on diaphragm muscle dysfunction caused by midazolam in dogs. Animals were divided into three groups of eight each. In each group, anesthetic doses (0.1 mg/kg initial dose plus 0.5 mg. kg(-1). h(-1) maintenance dose) of midazolam were administered for 60 min. Immediately after the end of midazolam administration, Group 1 received no study drug; Group 2 was infused small-dose (0.004 mg. kg(-1). h(-1)) flumazenil; Group 3 was infused with large-dose (0.02 mg. kg(-1). h(-1)) flumazenil. We assessed diaphragm muscle function (contractility and electrical activity) by transdiaphragmatic pressure (Pdi) and integrated electrical activity of the diaphragm (Edi). After midazolam was administered in each group, Pdi at low-frequency (20-Hz) and high-frequency (100-Hz) stimulation decreased from baseline values (P < 0.05), and values of Edi at 100-Hz stimulation were less than those obtained during baseline (P < 0.05). In Group 1, Pdi and Edi to each stimulus did not change from midazolam-induced values. In Groups 2 and 3, with an infusion of flumazenil, Pdi at both stimuli and Edi at 100-Hz stimulation increased from midazolam-induced values (P < 0.05). The increase in Pdi and Edi was more in Group 3 than in Group 2 (P < 0.05). We conclude that flumazenil recovers the diaphragm muscle dysfunction (reduced contractility and inhibited electrical activity) caused by anesthetic doses of midazolam in dogs. ⋯ In dogs, flumazenil recovers diaphragm muscle dysfunction (reduced contractility and inhibited electrical activity) caused by midazolam in a dose-related manner.
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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
Difficult endotracheal intubation in patients with sleep apnea syndrome.
Although sleep apnea syndrome (SAS) is common, studies assessing the anesthetic management of these patients are rare and consist mainly of case studies. We performed a retrospective case-control study to determine the incidence of difficult intubation in SAS patients and to determine the relationship between the severity of SAS and the occurrence of difficult intubation. Among 113 patients included (36 and 77 in the SAS and control groups, respectively), difficult intubation occurred more often in SAS patients than in controls (21.9% versus 2.6%, respectively; P < 0.05). No relationship was found between the severity of SAS and the occurrence of difficult intubation. Disappointingly, no single factor was associated with the occurrence of difficult intubation in SAS patients. We conclude that SAS is a risk factor for difficult intubation. ⋯ Because patients with sleep apnea syndrome have an increased risk of difficult endotracheal intubation and may present with cardiovascular disease, preoperative preventive measures should be undertaken to avoid untoward events.
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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
Substance abuse among physicians: a survey of academic anesthesiology programs.
Efforts to reduce controlled-substance abuse by anesthesiologists have focused on education and tighter regulation of controlled substances. However, the efficacy of these approaches remains to be determined. Our hypotheses were that the reported incidence of controlled-substance abuse is unchanged from previous reports and that the control and accounting process involved in distribution of operating room drugs has tightened. We focused our survey on anesthesiology programs at American academic medical centers. Surveys were sent to the department chairs of the 133 US anesthesiology training programs accredited at the end of 1997. There was a response rate of 93%. The incidence of known drug abuse was 1.0% among faculty members and 1.6% among residents. Fentanyl was the controlled substance most often abused. The number of hours of formal education regarding drug abuse had increased in 47% of programs. Sixty-three percent of programs surveyed had tightened their methods for dispensing, disposing of, or accounting for controlled substances. The majority of programs (80%) compared the amount of controlled substances dispensed against individual provider usage, whereas only 8% used random urine testing. Sixty-one percent of departmental chairs indicated that they would approve of random urine screens of anesthesia providers. ⋯ This survey indicates that the frequency of controlled substance abuse among anesthesiologists has changed little in the past few years, despite an increase in the control and accounting procedures for controlled substances as well as increased mandatory education.