Anesthesia and analgesia
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Anesthesia and analgesia · May 2001
Randomized Controlled Trial Clinical TrialThe safety and efficacy of sevoflurane anesthesia in infants and children with congenital heart disease.
We tested the hypothesis that sevoflurane is a safer and more effective anesthetic than halothane during the induction and maintenance of anesthesia for infants and children with congenital heart disease undergoing cardiac surgery. With a background of fentanyl (5 microg/kg bolus, then 5 microg. kg(-1). h(-1)), the two inhaled anesthetics were directly compared in a randomized, double-blinded, open-label study involving 180 infants and children. Primary outcome variables included severe hypotension, bradycardia, and oxygen desaturation, defined as a 30% decrease in the resting mean arterial blood pressure or heart rate, or a 20% decrease in the resting arterial oxygen saturation, for at least 30 s. There were no differences in the incidence of these variables; however, patients receiving halothane experienced twice as many episodes of severe hypotension as those who received sevoflurane (P = 0.03). These recurrences of hypotension occurred despite an increased incidence of vasopressor use in the halothane-treated patients than in the sevoflurane-treated patients. Multivariate stepwise logistic regression demonstrated that patients less than 1 yr old were at increased risk for hypotension compared with older children (P = 0.0004), and patients with preoperative cyanosis were at increased risk for developing severe desaturation (P = 0.049). Sevoflurane may have hemodynamic advantages over halothane in infants and children with congenital heart disease. ⋯ In infants and children with congenital heart disease, anesthesia with sevoflurane may result in fewer episodes of severe hypotension and less emergent drug use than anesthesia with halothane.
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Anesthesia and analgesia · May 2001
Plasma tranexamic acid concentrations during cardiopulmonary bypass.
Although tranexamic acid is used to reduce bleeding after cardiac surgery, there is large variation in the recommended dose, and few studies of plasma concentrations of the drug during cardiopulmonary bypass (CPB) have been performed. The plasma tranexamic acid concentration reported to inhibit fibrinolysis in vitro is 10 microg/mL. Twenty-one patients received an initial dose of 10 mg/kg given over 20 min followed by an infusion of 1 mg. kg(-1). h(-1) via a central venous catheter. Two patients were removed from the study secondary to protocol violation. Perioperative plasma tranexamic acid concentrations were measured with high-performance liquid chromatography. Plasma tranexamic acid concentrations (microg/mL; mean +/- SD [95% confidence interval]) were 37.4 +/- 16.9 (45.5, 29.3) after bolus, 27.6 +/- 7.9 (31.4, 23.8) after 5 min on CPB, 31.4 +/- 12.1 (37.2, 25.6) after 30 min on CPB, 29.2 +/- 9.0 (34.6, 23.8) after 60 min on CPB, 25.6 +/- 18.6 (35.1, 16.1) at discontinuation of tranexamic acid infusion, and 17.7 +/- 13.1 (24.1, 11.1) 1 h after discontinuation of tranexamic acid infusion. Four patients with renal insufficiency had increased concentrations of tranexamic acid at discontinuation of the drug. Repeated-measures analysis revealed a significant main effect of abnormal creatinine concentration (P = 0.02) and time (P < 0.001) on plasma tranexamic acid concentration and a significant time x creatinine concentration interaction (P < 0.001). ⋯ A 10 mg/kg initial dose of tranexamic acid followed by an infusion of 1 mg.kg(-1).h(-1)produced plasma concentrations throughout the cardiopulmonary bypass period sufficient to inhibit fibrinolysis in vitro. The dosing of tranexamic acid may require adjustment for renal insufficiency.
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Anesthesia and analgesia · May 2001
Clinical TrialContinuous fascia iliaca compartment block in children: a prospective evaluation of plasma bupivacaine concentrations, pain scores, and side effects.
We sought to determine the plasma concentrations of bupivacaine and its main metabolite after continuous fascia iliaca compartment (FIC) block in children. Twenty children (9.9 +/- 4 yr, 38 +/- 19 kg) received a continuous FIC block for either postoperative analgesia (n = 16) or femoral shaft fracture (n = 4). A bolus dose of 0.25% bupivacaine (1.56 +/- 0.3 mg/kg) with epinephrine was followed by a continuous administration of 0.1% bupivacaine (0.135 +/- 0.03 mg. kg(-)(1). h(-)(1)) for 48 h. Plasma bupivacaine levels were determined at 24 h and 48 h by using gas liquid chromatography. Heart rate, arterial blood pressure, respiratory rate, side effects, and pain scores were recorded at 4-h intervals during 48 h. No significant differences were found between mean plasma bupivacaine levels at 24 h (0.71 +/- 0.4 microg/mL) and at 48 h (0.84 +/- 0.4 microg/mL) (P = 0.33). FIC block provided adequate analgesia in most cases. No severe adverse effects were noted. We conclude that the bupivacaine plasma concentrations during continuous FIC block in children are within the safety margins. FIC block is well tolerated, and provides satisfactory pain relief in most cases. ⋯ In this study, we have shown that, in children, continuous fascia iliaca compartment block, a technique providing neural blockade of the thigh and the anterior part of the knee, was associated with safe plasma bupivacaine concentrations, was well tolerated, and provided satisfactory pain scores in most cases.
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Anesthesia and analgesia · May 2001
Can initial distribution volume of glucose predict hypovolemic hypotension after radical surgery for esophageal cancer?
We recently reported that the initial distribution volume of glucose (IDVG) reliably measures the central extracellular fluid volume in the presence or absence of fluid gain or loss. We examined which variables, including IDVG, can predict subsequent hypovolemic hypotension produced by the continuous shift of the extracellular fluid from the central to the peripheral compartment early after radical surgery for esophageal cancer. IDVG and plasma volume were calculated after measuring cardiac index (CI), central venous pressure, and pulmonary artery wedge pressure immediately after admission to the intensive care unit. Intraoperative fluid balance and urine volume were also recorded. Postoperative hypovolemic hypotension was clinically defined as systolic blood pressure < 80 mm Hg responsive to IV fluid administration. Either IDVG < 105 mL/kg or CI < 3.4 L. min(-1). m(-2) was associated with subsequent hypovolemic hypotension (P = 0.002 for the former and P = 0.00 03 for the latter), while remaining variables were not. IDVG and CI were well correlated (r = 0.8 7, n = 25, P = 0.0001). Our results suggest that IDVG can help predict the subsequent hypovolemic hypotension early after radical surgery for esophageal cancer. ⋯ Routine cardiovascular variables immediately after major surgery cannot predict the subsequent hypovolemic hypotension produced by the shift of the extracellular fluid. Glucose dilution using glucose 5 g and a one-compartment model can predict it simply and rapidly.
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Anesthesia and analgesia · May 2001
The impact on revenue of increasing patient volume at surgical suites with relatively high operating room utilization.
We previously studied hospitals in the United States of America that are losing money despite limiting the hours that operating room (OR) staff are available to care for patients undergoing elective surgery. These hospitals routinely keep utilization relatively high to maximize revenue. We tested, using discrete-event computer simulation, whether increasing patient volume while being reimbursed less for each additional patient can reliably achieve an increase in revenue when initial adjusted OR utilization is 90%. We found that increasing the volume of referred patients by the amount expected to fill the surgical suite (100%/90%) would increase utilization by <1% for a hospital surgical suite (with longer duration cases) and 4% for an ambulatory surgery suite (with short cases). The increase in patient volume would result in longer patient waiting times for surgery and more patients leaving the surgical queue. With a 15% reduction in payment for the new patients, the increase in volume may not increase revenue and can even decrease the contribution margin for the hospital surgical suite. The implication is that for hospitals with a relatively high OR utilization, signing discounted contracts to increase patient volume by the amount expected to "fill" the OR can have the net effect of decreasing the contribution margin (i.e., profitability). ⋯ Hospitals may try to attract new surgical volume by offering discounted rates. For hospitals with a relatively high operating room utilization (e.g., 90%), computer simulations predict that increasing patient volume by the amount expected to "fill" the operating room can have the net effect of decreasing contribution margin (i.e., profitability).