Anesthesia and analgesia
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We accomplished endotracheal intubation by using fluoroscopic direction in a patient presenting a difficult airway both on the basis of a preanesthetic physical examination and on the basis of a potential for cervical cord injury associated with complicated laryngoscopy. Under topical anesthesia, a multipurpose angiographic (MPA) catheter over a Bentson wire was advanced into the trachea under intermittent C-arm fluoroscopic guidance while the occiput, cervical spine, and mandible remained in a neutral position. The endotracheal tube was then easily advanced over the MPA catheter into the trachea, where the location was documented by fluoroscopic view. Because of judicious use of topical anesthesia and the small diameter and flexibility of the MPA catheter, the unsedated patient remained comfortable throughout the procedure. The stored data were later transferred to a compact disk, and a copy was provided to the patient as an adjunct to Medic-Alert. Unlike fiberoscopy, with which the view can be totally obscured by secretions, blood, and abnormal anatomy, the direction and location of the MPA catheter within the airway were easily identifiable throughout the procedure. The small diameter of the MPA (1.5-mm outer diameter) should allow placement of endotracheal tubes as small as 3.0-mm inner diameter--an option not available even with pediatric instruments. Although time was not a consideration, the procedure was accomplished in <12 min with 22 s of fluoroscopy. We believe that with experience, atraumatic intubation of a difficult airway could be accomplished routinely in less than 2 min with radiological-assisted intubation. ⋯ Radiologic-assisted intubation facilitated endotracheal intubation without sedation, instrumentation, or significant movement of the occiput, cervical spine, or mandible. The procedure was accomplished in <12 min and with only 22 s of fluoroscopy. This approach provides the ultimate adjunct to the preoperative airway physical evaluation while providing for immediate (or delayed) atraumatic endotracheal intubation. The diagnostic information and procedure can be recorded on a compact disk.
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Anesthesia and analgesia · May 2004
A survey of orthopedic surgeons' attitudes and knowledge regarding regional anesthesia.
We conducted a survey to explore the surgical attitudes and preferences regarding regional anesthesia among Canadian orthopedic surgeons. Surveys were returned by 468 (61%) of 768 surgeons. Forty-eight percent of respondents directed their patients' choice of anesthetic. Forty percent of surgeons directed their patients to choose regional anesthesia. The principal reasons for favoring regional anesthesia were less postoperative pain (32%), decreased nausea and vomiting (12%), and safety (14%). Reasons for not favoring regional anesthesia were delays in the induction of anesthesia (43%) and an unpredictable success rate (12%). This survey suggests that orthopedic surgeons are supportive of regional anesthesia. Barriers to increased popularity include perceived delays and unreliability. ⋯ Orthopedic surgeons understand the benefits of and are supportive of the use of regional anesthesia in their practices. Barriers to increased popularity include perceived operating room delays and lack of reliability.
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Anesthesia and analgesia · May 2004
A model for evaluating droperidol's effect on the median QTc interval.
Controversy surrounds the use of the antiemetic droperidol, because of the Food and Drug Administration-imposed "black box" warning alleging that even small doses of the drug can lead to serious (even fatal) arrhythmias when it is used for antiemetic prophylaxis during the perioperative period. We used mathematical modeling of electrocardiographic QT interval data published in a peer-reviewed manuscript to evaluate the relationship between the dose of droperidol (0.1-0.25 mg/kg i.v.) and QT(c) prolongation. In comparing the calculated QT(c) values based on the logarithm model (27-63 ms), the linear model (27-67 ms) and the square-root model (36-57 ms) to the actual measured QT(c) values (37-59 ms), the square-root model provided the best simulation of the experimental findings. Other models that we evaluated included the polynomial model and various exponent models (e.g., quartic-root model, cubic-root model, square model, and cubic model). The estimated median prolongation of the median QT(c) interval produced by droperidol 0.625-1.25 mg i.v. would vary from 9 +/- 3 to 18 +/- 3 ms. Therefore, this regression analysis suggests that small "antiemetic" doses of droperidol (< or =1.25 mg) would be unlikely to produce proarrhythmogenic effects in the perioperative period. ⋯ Using a square-root curve fit model to evaluate the relationship between the dose of droperidol and QT(c) prolongation, small-dose droperidol (0.625-1.25 mg i.v.) would be expected to produce <30-ms prolongation of the QT(c) interval. Therefore, small "antiemetic" doses of droperidol would not be expected to produce proarrhythmogenic effects when used for prophylaxis in surgical patients.
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Anesthesia and analgesia · May 2004
Multiple measures of anesthesia workload during teaching and nonteaching cases.
In this study, we sought to examine several measures of anesthesia provider workload during different phases of anesthesia care and during teaching and nonteaching cases. Clinical work was assessed in real-time during 24 general anesthetics performed by consenting anesthesia providers. Workload was measured using physiological (provider heart rate), psychological (self-assessment and observer rating), and procedural (response latency to an alarm light and workload density) techniques. Clinicians' heart rates, observer and self-reported workload scores, and nonteaching workload density were consistently increased during anesthetic induction and emergence compared with maintenance. In nonteaching cases, workload density correlated with heart rate and with psychological workload. Workload density during teaching cases did not decrease during the induction and was significantly greater than during nonteaching cases. Alarm-light response latency (a measure of clinical vigilance) was significantly prolonged during the teaching compared with nonteaching cases. These results suggest that intraoperative teaching increases the workload of the clinician instructor and may reduce vigilance during anesthesia care. Additionally, multiple workload measures may provide a more comprehensive profile of the work demands of clinical cases. ⋯ Psychological, physiological, and procedural workload measures during routine general anesthesia cases documented the increased work demands of induction and emergence. Intraoperative teaching increased workload and decreased vigilance, suggesting the need for caution when educating during patient care.
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Tissue plasminogen activator (tPA) has a prominent role in physiological fibrinolysis in vivo. Thrombosis has been associated with clinical scenarios (e.g., atherosclerotic disease) known to involve local decreases in tPA activity with concomitant formation of reactive nitrogen species such as peroxynitrite (OONO(-)), a molecule formed from nitric oxide and superoxide. We hypothesized that exposure of tPA to OONO(-) would result in a decrease in tPA activity. OONO(-) was generated with 3-morpholinosydnonimine (SIN-1), a molecule that produces both nitric oxide and superoxide. Recombinant tPA was incubated at 37 degrees C for 60 min with 0 microM SIN-1; 100 microM SIN-1; 100 microM SIN-1 and 4000 U/mL recombinant human superoxide dismutase; or 4000 U/mL recombinant human superoxide dismutase (n = 8 separate reactions per condition). Changes in tPA activity were assessed by addition of tPA samples to tissue factor-exposed human plasma and measuring clot fibrinolysis with a thrombelastograph. Exposure to SIN-1 resulted in a decrease in tPA-mediated fibrinolysis (<1% activity of tPA not exposed to SIN-1) that was significantly (P < 0.001) different from the other three conditions. There were no significant differences between the other conditions. We conclude that tPA is inhibited by OONO(-), and that OONO(-) may have a role in clinical thrombotic scenarios. ⋯ Tissue plasminogen activator (tPA) has a prominent role in fibrinolysis in vivo. Thrombosis has been associated with clinical scenarios involving decreases in tPA activity with concomitant formation of the oxidant peroxynitrite. We determined that peroxynitrite decreased tPA activity via thrombelastography. Peroxynitrite-mediated tPA inactivation may have a role in thrombotic states.