Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Clinical TrialDigital skin blood flow as an indicator for intravascular injection of epinephrine-containing simulated epidural test dose in sevoflurane-anesthetized adults.
I designed this study to determine the efficacy of heart rate (HR), systolic blood pressure (SBP), and digital skin blood flow (DSBF) in detecting intravascular injection after a simulated epidural test dose containing 15 mug of epinephrine in sevoflurane-anesthetized adults. In addition, the testing threshold using DSBF was derived. Eighty patients were randomized to receive either 0.5 minimum alveolar anesthetic concentration (MAC) sevoflurane or 1.0 MAC sevoflurane and nitrous oxide in oxygen (n = 40 for each sevoflurane concentration). Each group of patients was further randomized to receive either 3 mL of 1.5% lidocaine containing 15 mug of epinephrine IV or 3 mL of saline IV (n = 20 each). HR, SBP, and DSBF were monitored for 5 min after injection. By using the HR (positive if >or=10 bpm increase) and SBP (positive if >or=15 mm Hg increase) criteria, a positive response rate to epinephrine was 95% for both variables during 0.5 MAC and 90% during 1.0 MAC sevoflurane anesthesia. Injection of the test dose resulted in peak DSBF decrease by 87% +/- 8% and 81% +/- 12% at 52 +/- 10 and 53 +/- 13 s in the sevoflurane 0.5 and 1.0 MAC groups, respectively. Positive DSBF criterion, as determined from peak increases during saline administration, was a decrease in DSBF >or=15%. Using this value, the sensitivity, specificity, positive predictive value, and negative predictive value were 100% in both sevoflurane groups. In conclusion, DSBF was superior to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose. ⋯ This study examined the efficacy of digital skin blood flow to detect an intravascular injection of an epinephrine-containing epidural test dose. This new variable when measured with a laser Doppler flowmeter was superior to conventional hemodynamic criteria during sevoflurane anesthesia.
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Anesthesia and analgesia · Aug 2005
ReviewIntraoperative fluid restriction improves outcome after major elective gastrointestinal surgery.
Fluid therapy is one of the most controversial topics in perioperative management. There is continuing debate with regard to the quantity and the type of fluid resuscitation during elective major surgery. However, there are increasing reports of perioperative excessive intravascular volume leading to increased postoperative morbidity and mortality. ⋯ Furthermore, predetermined algorithms that suggest replacement of third space losses and losses through diuresis are unnecessary. Significant reduction in crystalloid volume can be achieved without encountering intraoperative hemodynamic instability or reduced (i.e., < 0.5 mL x kg(-1) x h(-1)) urinary output just by avoiding replacement of third space losses and preloading. Finally, there is a need for well-controlled studies in a well-defined patient population using clear criteria or end-points for perioperative fluid therapy.
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Anesthesia and analgesia · Aug 2005
Comparative StudyUltrasound guidance for facet joint injections in the lumbar spine: a computed tomography-controlled feasibility study.
We conducted this study to develop an ultrasound-guided approach for facet joint injections of the lumbar spine. Five zygapophyseal joints (L1-S1) on each side of 5 embalmed cadavers were examined by ultrasound for a total of 50 examinations. The joint space was demonstrated under ultrasound guidance. The midpoint of the joint space, defined as the middle of its cranio-caudal extension on its dorsal surface, was taken as a reference point, and its position was computed from its depth and lateral distance from the spinous process. Forty-two of 50 approaches could be clearly visualized. Subsequently, these distances were compared to those obtained by computed tomography (CT). To assess the efficacy of ultrasound in the needle placement, all lumbar facet joints were approached in one embalmed cadaver. The exact placement of the needle tips was again evaluated by CT. Ultrasound and CT measurements showed the same mean depth and lateral distance to the reference point, 3.15 +/- 0.5 cm and 1.9 +/- 0.6 cm, respectively. Pearson's coefficient of correlation was 0.86 (P < 0.0001) between ultrasound and CT. All 10 needle tips were within the joint space during simulated facet joint injections. We conclude that ultrasound guidance might be a useful adjunct for facet joint injections in the lumbar spine. ⋯ This study was designed to develop an ultrasound-guided approach to the facet joints of the lumbar spine and to assess its feasibility and accuracy by means of a comparison to computed tomography images. The imaging study demonstrated a significant correlation between ultrasound and computed tomography measurements. During simulated facet injection, ultrasound guidance consistently resulted in accurate needle placement.
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Anesthesia and analgesia · Aug 2005
Clinical TrialPredictive factors of early postoperative urinary retention in the postanesthesia care unit.
Urinary retention is a common postoperative complication associated with bladder overdistension and the risk of permanent detrusor damage. The goal of this study was to determine predictive factors of early postoperative urinary retention in the postanesthesia care unit (PACU). We prospectively collected, in 313 adult patients, variables including age, gender, previous history of urinary tract symptoms, type of surgery and anesthesia, intraoperative administration of anticholinergics, amount of intraoperative fluids, IV morphine titration, and bladder volume on entry to the PACU. For each patient, bladder volume was measured by ultrasound on entry and before discharge from the PACU. Urinary retention was defined as a bladder volume larger than 600 mL with an inability to void within 30 min. Predictive factors were identified by multivariate analysis. The incidence of urinary retention in the PACU was 16%. In the multivariate analysis only the amount of intraoperative fluids (>or=750 mL; P = 0.02; odds ratio = 2.3), age (>or=50 yr; P = 0.008; odds ratio = 2.4), and bladder volume on entry to PACU (>or=270 mL; P = 0.0001; odds ratio = 4.8) were found to independently increase the risk of urinary retention. Considering the clinical impact of undiagnosed postoperative urinary retention, these results suggest systematic evaluation of bladder volume with a portable ultrasound device in the PACU, especially in patients with risk factors. ⋯ In this observational study, the ultrasound monitoring of bladder volume in the postanesthesia care unit (PACU) revealed that postoperative urinary retention occurred with an incidence of 16%. Age (>or=50 yr), amount of intraoperative fluid volume (>or=750 mL), and bladder volume on entry to PACU (>or=270 mL) were independent predictive factors for this complication.
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Anesthesia and analgesia · Aug 2005
Changes in concentrations of free propofol by modification of the solution.
Because free propofol is thought to be responsible for pain on injection, we investigated the changes in concentrations of free propofol by modifying two kinds of propofol products in a medium- and long-chain triglyceride (MCT/LCT) emulsion and in an LCT emulsion. The techniques used in this study were 1) mixing 2% lidocaine (10:1), 2) mixing 5% dextrose in acetated Ringer's solution to reduce pH (10:1), and 3) changing the temperature to 4 degrees , 20 degrees , and 36 degrees C. The propofol preparations were dialyzed for 24 h, and the receptor medium was analyzed using high-performance liquid chromatography. The concentration of free propofol in propofol MCT/LCT was significantly smaller by 30% than that in propofol LCT. Neither mixing lidocaine nor cooling reduced the concentrations of free propofol in both products, but the concentrations were reduced by a decrease in pH and by an increase in temperature. Because mixing lidocaine can induce instability in an emulsion of propofol and warming can rapidly induce microbial growth, injection of lidocaine before propofol administration is recommended to reduce the pain on injection. The concentrations of free propofol in propofol MCT/LCT were significantly smaller (by approximately 30%-45%) than those in propofol LCT during any situation in this study. ⋯ Neither mixing lidocaine nor cooling reduced the concentrations of free propofol in both products but the concentrations were reduced by a decrease in pH and by an increase in temperature. Propofol medium- and long-chain triglycerides had significantly smaller concentrations by approximately 30%-45% than those in propofol long-chain triglycerides during any situation in this study.