Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2003
Clinical TrialSevoflurane in exhaled air of operating room personnel.
Evidence on potential health hazards arising from exposure to volatile anesthetics remains controversial. Exposure may, in principle, be supervised by monitoring of ambient air or, alternatively, in vivo. We used the Proton Transfer Reaction-Mass Spectrometry to screen the breath of 40 operating room staff members before operating room duty, 0, 1, 2, and 3 h after duty, and before commencing duty on the consecutive day, and control persons. Staff members exhibited significantly increased sevoflurane levels in exhaled air after duty, with a mean of 0.80 parts per billion as compared with baseline values of 0.26 parts per billion (P < 0.05). Analysis of variance with adjustment for within correlation (repeated measurements) showed a statistically significant time-effect (P < 0.001). We conclude that (a) Proton Transfer Reaction-Mass Spectrometry biomonitoring of exhaled sevoflurane can serve as a simple and rapid method to determine volatile anesthetic excretion after occupational exposure, and (b) significant concentrations of sevoflurane may be continuously present in persons exposed to sevoflurane on a daily basis. ⋯ The present study depicts the profile of volatile anesthetics, isoflurane and sevoflurane, in exhaled air of ambulatory patients. Biomonitoring of expired anesthetic concentrations is a noninvasive and rapid method to determine volatile anesthetic excretion.
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Anesthesia and analgesia · Oct 2003
Comparative StudyA laboratory evaluation of the level 1 rapid infuser (H1025) and the Belmont instrument fluid management system (FMS 2000) for rapid transfusion.
In this investigation I compared the heating capabilities, infusion rates, and air management system of the new FMS 2000 and the Level 1 infusion systems. A rollerhead pump was placed at the position of the IV bag spikes on the Level 1 disposable set and used to match the flow of the rollerhead pump of the FMS 2000. Infusate temperature was measured at 250 and 500 mL/min by using packed red blood cells (PRBC) at the infusate supply and distal end of the disposable tubing. Tubing lengths were equal for both systems. Devices were set at maximum flow while temperatures were measured as described previously. Flow was measured with a graduated cylinder and stopwatch. Air management was evaluated with a 10-mL air bolus injected proximal to the heat exchanger at maximum flow. Air passing through the system was collected and measured. At 250 mL/min, both devices provided infusate at >or=37 degrees C. At 500 mL/min, only the FMS 2000 provided PRBC at >or=37 degrees C. PRBC infusate temperature decreased over time with the Level 1 device. The FMS 2000 delivered PRBC at its maximum flow rate of 500 mL/min. The Level 1 attained a maximum flow of 575 mL/min of PRBC with a temperature of 32 degrees C. Air (10 mL) was recovered from the distal tubing of the Level 1. No air was recovered from the tubing of the FMS 2000. In this laboratory investigation, the FMS 2000 performance was superior with respect to providing PRBC at physiologic temperatures (at 500 mL/min) and with respect to air detection and elimination compared with current widely used pressure-infuser technology. ⋯ The FMS 2000 and Level 1 H1025 warming capabilities were similar at metered flows of 500 mL/min. At more rapid flow rates, which are achieved by the H1025, fluid warming decreases dramatically. The air-detection and -elimination system of the FMS 2000 is superior to that of the H1025.
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Anesthesia and analgesia · Oct 2003
Case ReportsSciatic nerve palsy after total hip arthroplasty in a patient receiving continuous lumbar plexus block.
We report a case of late-onset postoperative sciatic palsy after total hip arthroplasty in a 30-yr-old man with congenital hip dysplasia. The patient was receiving continuous lumbar plexus blockade and had received low-molecular-weight heparin 3 h before the onset of symptoms. Anatomic distinction between the nerve block and the sciatic palsy facilitated rapid diagnosis and treatment of a periarticular hematoma, with resulting neurologic recovery. This case illustrates that, with the expanded role of regional anesthetic techniques in acute pain management, the finding of a new postoperative deficit must be jointly investigated by both anesthesiologists and surgeons. Timely and open communication between services is critical because rapid intervention may be essential to achieving full recovery of an affected nerve. ⋯ A case is presented of sciatic palsy developing after total hip arthroplasty in a patient receiving a continuous lumbar plexus block. The case highlights various issues in the use of continuous peripheral nerve blocks for postoperative analgesia.
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Anesthesia and analgesia · Oct 2003
Behavioral monitoring and urine toxicology testing in patients receiving long-term opioid therapy.
No study has examined the role of urine toxicology in addition to behavioral monitoring in patients receiving opioid therapy for chronic pain. All patients maintained on chronic opioid therapy by the two senior authors at two university pain management centers were monitored for 3 yr with urine toxicology testing and for behaviors suggestive of inappropriate medication use. We retrospectively extracted demographic information, aberrant drug-taking behaviors, and urine toxicology information from the medical record. For 122 patients maintained on chronic opioid therapy, 43% (n = 53) had a "problem" (either positive urine toxicology or one or more aberrant drug-taking behaviors). Of patients with no behavioral issues, 21% (n = 26) had a positive urine screen for either an illicit drug or a nonprescribed controlled medication. Of patients with a negative urine screen, 14% (n = 17) had one or more behavioral issues. Monitoring both urine toxicology and behavioral issues captured more patients with inappropriate drug-taking behavior than either alone. Requiring a report of behavioral issues and urine toxicology screens for patients receiving chronic opioids creates a more comprehensive monitoring system than either alone. ⋯ Monitoring both urine toxicology and aberrant behavior in chronic-pain patients treated with opioids identified more problem patients than by monitoring either alone. The authors recommend routine urine testing on all patients prescribed opioids for noncancer pain and as a required element in all opioid analgesic studies.
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Anesthesia and analgesia · Oct 2003
The hemodynamic and metabolic effects of shivering during acute normovolemic hemodilution.
To assess the hemodynamic and metabolic effects of shivering during extreme normovolemic hemodilution, we anesthetized 16 pigs with fentanyl-midazolam-pancuronium. Mild hypothermia (36.5 degrees +/- 0.1 degrees C) was induced by surface cooling, and the animals were randomized to either a control group (hemoglobin 118 +/- 3 g/L) or a hemodilution group (hemoglobin 52 +/- 2 g/L). In the latter group, blood was replaced with an isotonic Ringer's acetate/dextran 70 solution. Shivering was allowed to occur by a controlled decrease in the infusion rate of pancuronium. Shivering increased oxygen consumption (VO(2)) in both groups (P < 0.001). Initially, this was predominantly compensated for by an increased oxygen extraction ratio (ER), but when VO(2) was 2.3 +/- 0.2 times baseline, critical levels of mixed venous oxygenation (SVO(2) = 18% +/- 2%; PVO(2) = 22.5 +/- 1.5 mm Hg) and ER (82% +/- 3%) were recorded in anemic animals. Control animals did not reach critical levels until VO(2) was maximal (3.7 +/- 0.3 times baseline). Maximal attained VO(2) was less (2.9 +/- 0.1 times baseline) in the anemic animals (P = 0.01), and at this stage two of these pigs had myocardial lactate production, one of which died in ventricular fibrillation. Coronary perfusion pressure was significantly less (P < 0.001) in the anemic animals. We conclude that in this experimental model, maximal shivering as measured by VO(2) was limited in hemodiluted animals, and left ventricular oxygen balance was marginal, as evidenced by a decreased lactate uptake and extraction. ⋯ The effect of acute increases in oxygen consumption (shivering) on severely anemic individuals has not been evaluated. In this experimental model, left ventricular oxygen balance was marginal, as evidenced by decreased lactate extraction.