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PubMedDate not supplied

[Pharmacokinetic monitoring of 24-hour infusion of methotrexate in an adult population with non-Hodgkin lymphoma].

OBJECTIVES: To describe the behavior and variability of methotrexate (MTX) pharmacokinetic parameters in patients with non-Hodgkin lymphoma (NHL) and to suggest a monitoring system to optimize sample collection using a bayesian method. METHOD: Two adult patient groups diagnosed with different NHL types were studied. Group I was made up of 9 patients aged 53 +/- 16 years who received MTX at a mean dose of 1.652 +/- 327 mg per course. Group II was made up of 7 patients aged 53 +/- 14 years who received MTX at a mean dose of 1.862 +/- 220 mg per course. No statistically significant differences between groups were seen. Serum MTX measurements were performed using polarized immunofluorescence (TDx system). The pharmacokinetic analysis was performed using Abbottbase Pharmacokinetics Systems (PKS) software, adjusting experimental data according to a bicompartmental linear model for intravenous delivery using non-linear regression in Group I and Bayesian estimates in Group II. By estimating mean square error and linear regression between predicted and experimental concentrations, the capability of the Bayesian method implemented in PKS to predict plasma MTX concentration at 48 hours post-infusion was evaluated. The safety of MTX therapy was assessed using patient medical histories and then scoring toxicity using the WHO scale. RESULTS: Pharmacokinetic parameters obtained for group I included: alpha (h(-1)) = 0.38 +/- 0.12; beta (h(-1)) = 0.07 +/- 0.03; K12 (h(-1)) = 0.02 +/- 0.02; K21 (h(-1)) = 0.09 +/- 0.09; K13 (h(-1)) = 0.34 +/- 0.12; Vc (l/kg) = 0.53 +/- 0.23; Vss (l/kg) = 0.62 +/- 0.26; Cl (l/kg.h) = 0.16 +/- 0.06. The error for the PKS population model in measuring plasma MTX concentration at 48 hours post-infusion in Group II was calculated in accordance with three sampling schemes -12 h, 24 h, and both. It was -14.58 x 10(-3), -15.70 x 10(-3) and -14.67 x 10(-3), respectively. Eqm was 9.58 x 10(-3), 2.39 x 10(-3), and 1.02 x 10(-3), respectively. CONCLUSION: An MTX monitoring scheme is suggested based on a Bayesian method implementing pharmacokinetic parameters obtained from an adult population with NHL, which allows therapy safety and the clearance profile of MTX to be predicted from a single sample collected at 24 hours post-infusion.

Antimetabolites, Antineoplastic↗
PubMed1990

Alcohol consumption as a risk factor for high blood pressure from the Cardiovascular Diseases and Alimentary Comparison Study. CARDIAC Cooperative Research Group).

The relationship between alcohol consumption and blood pressure (BP) was studied in 29 centers in 12 countries as part of the International Cooperative Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. From each population, 100 men and 100 women aged 50-54 were randomly selected for BP measurement by automated system and for a standardized interview to complete the questionnaire relating to alcohol consumption. In cross-center simple linear regression analysis, mean alcohol consumption calculated from a previous week's drinking did not show a linear association to BP. In within-center multiple linear regression analysis, relationships between high alcohol intake (much greater than 300 g/week) and BP were assessed among 26 centers with high alcohol drinkers after being adjusted for other confounding variables. Positive associations of high alcohol intake with systolic BP (SBP) and diastolic BP (DBP) were noted in 17 and 16 centers, respectively. Thus, high alcohol intake was positively and independently associated with BP in individual subjects.

Alcohol Drinking↗
PubMed2006

Predicting germination response to temperature. I. Cardinal-temperature models and subpopulation-specific regression.

BACKGROUND AND AIMS: The purpose of this study was to compare the relative accuracy of different thermal-germination models in predicting germination-time under constant-temperature conditions. Of specific interest was the assessment of shape assumptions associated with the cardinal-temperature germination model and probit distribution often used to distribute thermal coefficients among seed subpopulations. METHODS: The seeds of four rangeland grass species were germinated over the constant-temperature range of 3-38 degrees C and monitored for subpopulation variability in germination-rate response. Subpopulation-specific germination rate was estimated as a function of temperature and residual model error for three variations of the cardinal-temperature model, non-linear regression and piece-wise linear regression. The data were used to test relative model fit under alternative assumptions regarding model shape. KEY RESULTS: In general, optimal model fit was obtained by limiting model-shape assumptions. All models were relatively accurate in the sub-optimal temperature range except in the 3 degrees C treatment where predicted germination times were in error by as much as 70 d for the cardinal-temperature models. CONCLUSIONS: Germination model selection should be driven by research objectives. Cardinal-temperature models yield coefficients that can be directly compared for purposes of screening germplasm. Other model formulations, however, may be more accurate in predicting germination-time, especially at low temperatures where small errors in predicted rate can result in relatively large errors in germination time.

Germination↗
PubMed2006

Failure of a Web-based educational tool to improve residents' scores on the American Board of Surgery In-Training Examination.

HYPOTHESIS: Usage of a Web-based educational tool will improve residents' scores on the American Board of Surgery In-Training Examination (ABSITE). DESIGN: Before and after trial. SETTING: Academic surgical residency in a tertiary care university hospital. PARTICIPANTS: Nineteen postgraduate year 1 (PGY1) and PGY2 residents. INTERVENTION: All PGY1 and PGY2 residents were given unlimited access to a Web-based educational tool aimed at early-level residents in surgery. The educational tool covers the basic science of surgery and basic concepts of clinical surgery and uses a variety of educational techniques (readings, problem-based learning, case-based learning, and practice tests). Although residents were encouraged to complete the learning package, they were not required to do so. MAIN OUTCOME MEASURES: The ABSITE scores and changes in ABSITE scores were compared with the amount of time residents spent using the program and the number of tutorials completed. RESULTS: There was no significant difference in ABSITE scores before or after the use of the Web-based educational tool. There was no significant relationship between use of the tool (either in total time or total tutorials) and ABSITE score. For PGY2 residents, there was a negative relationship between total time spent on the program and ABSITE score (linear regression analysis best-fit slope, -0.20 +/- 0.1; r2 = 0.33) and total tutorials completed and ABSITE score (linear regression analysis best-fit slope, -0.34 +/- 0.22; r2 = 0.25). CONCLUSION: There was no demonstrable beneficial effect of a Web-based educational tool on cognitive knowledge of residents as measured by ABSITE scores.

Computer-Assisted Instruction↗
PubMed2003

Genetic and protein markers related to in situ growth and multiplicity in small sporadic colorectal adenomas.

BACKGROUND: Some early genetic events in the development of colorectal adenomas are known, but their relationship to in vivo growth characteristics is uncertain. This study compared in situ size changes and other clinicopathological variables with selected genetic and protein markers. METHODS: 56 adenomas (< or = 10 mm) from 39 patients were analysed for APC, CTNNB1 and K-ras mutations, allelic imbalance on 1p and 18q, microsatellite instability and immunohistochemical expression of HLA-DR, BAX, BCL-2 and Ki-67. For 42 of the adenomas, in situ growth was measured over 3 years. The total number of polyps in each patient was recorded. RESULTS: K-ras was mutated in 8/56 adenomas. None of the regressing adenomas revealed such mutations, compared to 20% in those that maintained or increased their size. Multivariate linear regression analysis showed that tumour growth was higher in females compared to males, and was even higher in the presence of a K-ras mutation. APC mutations were found in 37/56 adenomas. CTNNB1 mutations were found in 2/19 adenomas without APC mutation. Deletions of 1p were found in 12/56 adenomas and, seemingly, most frequent in patients with few tumours. The most frequently expressed protein was BAX (33/41), but neither this nor the other proteins showed associations with an in situ growth pattern. CONCLUSION: The multivariate linear regression model showed that patient gender and the presence of K-ras mutation had significant effects on tumour growth. The lack of the proliferative stimulus resulting from a K-ras mutation may contribute to the process of adenoma regression.

Adenomatous Polyposis Coli Protein↗
PubMed1998

Clinical evaluation of the Abbott Qvue-OptiQ continuous cardiac output system in critically ill medical patients.

PURPOSE: The aim of this study was to evaluate the reliability of a new continuous cardiac output (CCO) monitoring device (Qvue/OptiQ system; Abbott Critical Care Systems, Mountain View, CA) based on the pulsed warm thermodilution technique in critically ill medical patients. METHODS: Nineteen patients with cardiogenic or septic shock were included in the study. Pairs of CCO and intermittent bolus cardiac output (ICO) were noted at least every 6 hours for determination of bias, precision, and limits of agreement. Simultaneously, blood samples were collected, and arterial-venous oxygen content difference (C[a-v]O2) was determined. A multiple stepwise logistic regression was used to identify situations associated with a CCO-ICO difference exceeded 20%. A multiple linear regression was performed to analyze the respective accuracy of CCO and ICO to predict the variations of C[a-v]O2. RESULTS: A total of 203 pairs of cardiac output measurements was obtained. The bias was 0.12 L/min (1.2% of pairs mean) and the precision 1.0 L/min (13%). The 95% limits of agreement were between -1.7 L/min (-25%) and 1.9 L/min (+26%). Low blood temperatures and heart rates above 120 beats/min were significantly associated with a ICO-CCO difference higher than 20%. In a multiple linear regression, CCO was significantly correlated with C[a-v]O2, an independent reflection of the patient's cardiac output; by contrast, ICO did not. CONCLUSION: These results suggest that ICO and CCO measurement by the Qvue/OptiQ system are interchangeable, except for temperature or heart rate extreme values.

Cardiac Output↗
PubMed2003

Cardiovascular hemodynamics: relationships with insulin resistance in obese children.

We investigated blood pressure (BP), cardiac output (CO), and systemic vascular resistance (SVR) and their relationships with insulin and glucose blood levels in a group of 24 obese children (mean age, 11.9 +/- 2.1 years; 19 males). The data were compared to those obtained from a group of 19 healthy controls of the same age (12.4 +/- 2.1 years; p = NS; 13 males). BP at rest was measured and all subjects underwent an exercise testing on the treadmill (Bruce Prot.), time of exercise, maximal heart rate, maximum systolic blood pressure, CO, and SVR at rest and at peak exercise were considered. Only in the OC group were an oral glucose tolerance test were performed to calculate insulin sensitivity index (ISI) and echocardiography performed to determine the left ventricular mass (LVM). The relationships between cardiovascular and metabolic parameters were investigated. Student's t-test and linear regression analysis were used when appropriate. OC had a significant reduction in TE and higher BP, and linear regression analysis showed significant correlations between BP, ISI, and LVM. We speculate that OC need a regular cardiovascular and metabolic screening to prevent the development of early cardiovascular damage.

Cardiac Output↗
PubMed2005

Varying effects of corneal thickness on intraocular pressure measurements with different tonometers.

AIMS: To compare the intraocular pressure (IOP) measurements using the Goldmann applanation tonometer (GAT), noncontact tonometer (NCT), and ocular blood flow tonometer (OBFT), and to evaluate the effects of varying central corneal thickness (CCT) on the readings. METHODS: Ultrasound pachymetry and tonometry were performed on 170 eyes. Using the corrected GAT values that took CCT into account as the standard, we calculated the NCT and OBFT measurement errors related to the CCT variable by a linear regression model. Group comparisons were performed with the chi2 test and one-way ANOVA test. The correlation between the various tonometer measurements was analysed by Pearson's correlation method. RESULTS: Both the NCT (r=0.872, P<0.001) and OBFT measurements (r=0.861, P<0.001) were highly correlated with the GAT measurements. IOP measurements using the three tonometers were all correlated with CCT (all P<0.001), with the NCT measurements showing the greatest regression coefficient (beta=0.063, r=0.650) and the GAT measurements the least (beta=0.037, r=0.496). A linear regression model indicated that a 10 microm change in CCT resulted in a NCT measurement deviation of 0.47-0.98 mmHg and an OBFT measurement deviation of 0.29-0.81 mmHg. CONCLUSION: Pressure readings with the GAT, NCT, and OBFT are all affected by CCT, with the NCT being the one most affected and the GAT the least. Our findings suggest CCT an essential variable to consider in interpreting IOP readings, especially for the NCT measurements.

Adult↗
PubMed1999

Evaluation of laparoscopic skills: a 2-year follow-up during residency training.

OBJECTIVE: To evaluate laparoscopic technical skill in surgical residents over a 2-year period. DESIGN: The laparoscopic technical skills of general surgical residents were evaluated using the MISTELS program. This provides an objective evaluation of laparoscopic skill, taking into account precision and speed. SETTING: Inanimate laparoscopic skills centre. PARTICIPANTS: Ten general surgical residents (5 PGY1, 3 PGY2 and 2 PGY3 residents) who were required to complete 3 structured laparoscopic tasks. OUTCOME MEASURES: A composite score incorporating precision and timing was assigned to each task. The paired t-test was used to compare performance of each resident at the 2 levels of their residency training for each task. Linear regression analysis was used to correlated level of training and total score (sum of all tasks). RESULTS: Linear regression analysis demonstrated a highly significant correlation between level of training and total score (r = 0.82, p < 0.01). There was a significant increase in scores in the cutting and suturing task over the 2-year period (p < 0.01). Transferring skills did not improve significantly (p = 0.11). CONCLUSIONS: Performance in the simulator improved over residency training and was correlated highly with postgraduate year. This simulator model is a valuable teaching tool for training and evaluation of basic laparoscopic tasks in laparoscopic surgery.

Canada↗
PubMed2004

Increased brain apparent diffusion coefficient in tuberous sclerosis.

PURPOSE: To evaluate the water diffusivity of normal-appearing white matter (NAWM) in patients with tuberous sclerosis complex compared with that in control subjects. MATERIALS AND METHODS: Diffusion and conventional magnetic resonance (MR) imaging examinations were performed in 18 patients with clinically established tuberous sclerosis complex (10 male and eight female patients; mean age, 20.1 years; range, 12-30 years), as well as in 18 age-matched control subjects (nine male and nine female; mean age, 20.2 years; range, 11-28 years). Apparent diffusion coefficients (ADCs) were generated, and small elliptic regions of interest were manually placed both in perilesional NAWM and in six anatomic locations of NAWM remote from hamartomatous lesions. Perilesional ADCs were compared with those at the same anatomic site on the contralateral side of the brain (generalized linear regression analysis). ADCs from the predetermined sites in patients were compared with those in control subjects (generalized linear regression analysis). RESULTS: Supratentorial ADCs were higher in patients with tuberous sclerosis complex than in control subjects, and statistically significant differences were observed in the occipital white matter, frontal white matter, centrum semiovale, parietal white matter, and corona radiata (for each location, P <.001). Significant increases were also seen in the perilesional NAWM compared with NAWM at the same anatomic locations on the contralateral side (P <.001). Infratentorial ADCs were normal. CONCLUSION: Significant ADC increases were measured in the supratentorial NAWM.

Adolescent↗
PubMed2005

The use of correlation and regression methods in optometry.

Correlation and regression are two of the statistical procedures most widely used by optometrists. However, these tests are often misused or interpreted incorrectly, leading to erroneous conclusions from clinical experiments. This review examines the major statistical tests concerned with correlation and regression that are most likely to arise in clinical investigations in optometry. First, the use, interpretation and limitations of Pearson's product moment correlation coefficient are described. Second, the least squares method of fitting a linear regression to data and for testing how well a regression line fits the data are described. Third, the problems of using linear regression methods in observational studies, if there are errors associated in measuring the independent variable and for predicting a new value of Y for a given X, are discussed. Finally, methods for testing whether a non-linear relationship provides a better fit to the data and for comparing two or more regression lines are considered.

Humans↗
PubMed2000

[11C]flumazenil metabolite measurement in plasma is not necessary for accurate brain benzodiazepine receptor quantification.

In this work, a mathematical correction for metabolites has been validated which estimates the relative amount of [11C]flumazenil ([11C]FMZ) in the total plasma curve from the tissue kinetic data without the need for direct metabolite measurement in blood plasma samples. Kinetic data were obtained using a 90-min three-injection protocol on five normal volunteers. First, the relative amount of [11C]FMZ in plasma was modelled by a two-parameter exponential function. The parameters were estimated either directly by fitting this model to the blood plasma metabolite measurements, or indirectly from the simultaneous fitting of tissue time activity curves from several brain regions with a non-linear FMZ kinetic model. Second, the direct and indirect metabolite corrections were fixed and the FMZ compartmental parameters were determined on a regional basis in the brain. The validation was performed by comparing the regional values of benzodiazepine receptor density Bmax and equilibrium dissociation constant Kd obtained with the direct metabolite correction with those values obtained with the indirect correction. For Bmax, the correlation coefficient r2 was above 0.97 for all subjects and the slope values of the linear regression were within the interval [0.97, 1.2]. For Kd, r2 was above 0.96, and the slope values of the linear regression were within the interval [0.99, 1.1]. Simulation studies were performed in order to evaluate whether this metabolite correction method could be used in a clinical protocol where only a single [11C]FMZ injection and a linear compartmental model are used. The resulting [11C]FMZ distribution volume estimates were found to be linearly correlated with the true values, with r2=1.0 and a slope value of 1.1. The mathematical metabolite correction proved to be a feasible and reliable method to estimate the relative amount of [11C]FMZ in plasma and the compartmental model parameters for three-injection protocols. Although validation with real data is necessary, simulation results suggest that our analysis method may also be applied to single-injection protocols.

Adult↗
PubMed1990

Individual variation in line bisection: a study of normal subjects with application to the interpretation of visual neglect.

Investigations of left visuo-spatial neglect are reviewed with special reference to line bisection performance. Attention is then drawn to inconsistencies in the direction and magnitude of transection displacements in group studies of normal controls. We argue that the lack of reliable information about normal mechanisms for line bisection makes it impossible to interpret pathological performance in neglect. Accordingly, we report a case-series of 22 normal young adults, each of whom bisects 10 lines of differing lengths 10 times each. There is very substantial between-subject variation in both the magnitude and direction of the linear regression of transection displacement on line length; there are likewise considerable differences in the magnitude of the linear regression of standard deviation on line length. These two sources of individual variation are uncorrelated. We propose a psychophysical theory of line bisection, and suggest that the basic mechanisms responsible for task-performance are qualitatively intact in visuo-spatial neglect, albeit quantitatively impaired.

Adult↗
PubMed2006

Effects of breath-hold diving on bone mineral density of women divers.

OBJECTIVES: The relationship between bone mineral density (BMD) and swimming has been thoroughly researched. The aim of this study was to determine the effects of breath-hold diving on the BMD in the proximal femurs of women divers. METHODS: A case-control observational study was carried out using health-checks of divers and control subjects at a hospital in Jeju City, South Korea. Women divers (N=61) were matched individually with non-diver controls (N=61) by age, weight, and postmenopausal year. The bone mineral densities of their proximal femurs (total hip, femoral neck) were assessed by dual-energy X-ray absorptiometry. RESULTS: The average diving year of women divers was 34+/-13 years. The BMD of divers was higher than that of controls in the total hip and femur neck area (P<0.05). On multiple linear regression analysis, age and body weight were predictors of proximal femur bone mineral densities in divers. On linear regression analysis of the proximal femur BMD according to age in divers and controls, the bone mineral densities of divers tend to decrease more rapidly than those of controls in all two areas of the proximal femurs. CONCLUSIONS: Our study results may suggest that diving in a high-pressure environment is an osteogenic stimulus. However, the weight-supported environment in diving exerts an effect that reduces BMD proportionately to the time spent in the water.

Absorptiometry, Photon↗
PubMed2003

Central properties of the essential oil and the crude ethanol extract from aerial parts of Artemisia annua L.

The present study evaluated the central activity of the essential oil and the ethanolic extract from Artemisia annua L. in animals as a part of a psychopharmacological screening of this plant. The extract was prepared with fresh leaves in ethanol (AEE) and the essential oil (AEO) was obtained by hidrodestilation. The ED(50) and the LD(50) obtained for the essential oil were 470mg/kg (correlation coefficient r=0.97333 and linear regression y=-26.52x+0.158) and 790mg/kg, and for the extract, 450mg/kg (correlation coefficient r=0.99266 and linear regression y=-27.34+0.156) and more than 2g/kg, respectively. The doses increased the latency time to convulsions induced by picrotoxin and pilocarpine but prevented the onset of pentylenotetrazol and strychnine induced seizures. In addition to, the products have caused marked inhibition in the Rota-rod assay. According to the results, the AEO has a high acute toxicity and a possible cholinergic action, and the AEE showed a possible central activity as dopaminergic and cholinergic agents, and did not present a significant acute toxicity. These differences should be due to chemical substances present in each product. These products had no significant effect as an anticonvulsant, while exhibited a strong depressant activity on the CNS.

Animals↗
PubMed2006

Association between serum uric acid level and components of the metabolic syndrome.

BACKGROUND: Serum uric acid (UA) level has been suggested to be associated with factors that contribute to the metabolic syndrome. However, the association between metabolic syndrome and UA has not been elucidated. We sought to determine the association between serum UA level and the number of components that contribute to the metabolic syndrome, and which component was associated most with higher serum UA level. METHODS: A consecutive sample was taken of the health examinations of all hospital staff who were assessed between January 2004 and December 2004 in a medical center. A total of 3,065 subjects aged 18 to 81 years (635 males, 2,430 females) participated. Blood tests and all physical variables were examined using standard methods. Subjects were divided into 5 groups according to their possession of 0, 1, 2, 3 or > or = 4 components of the metabolic syndrome. The differences in all variables between groups were analyzed by ANOVA. The relationship between serum UA level and the number of metabolic components was determined by linear regression analysis. The contribution to elevated UA of possessing different risk factors was determined by a multivariate linear regression model. RESULTS: Mean serum UA level increased as the number of metabolic factors increased. Serum UA level was higher in subjects with abnormal triglyceride (TG), waist circumference, high-density lipoprotein cholesterol (HDL-C) level and blood pressure (BP),with mean increases in UA level of 22.8, 21.4, 14.4 and 9.4 micromol/L, respectively (p < or = 0.001), compared to subjects with normal levels. After controlling for body mass index, abnormal TG, HDL-C and BP continued to account, in order of influence, for elevated UA. CONCLUSION: Serum UA level was elevated significantly as the number of metabolic components increased. Abnormal TG had the most influence on serum UA. A prospective study is warranted to determine if the prevention or treatment of hyperuricemia affects the development of metabolic syndrome.

Adult↗
PubMed1991

Reassessment of the single intravenous injection method with inulin for measurement of the glomerular filtration rate in man.

1. Factors influencing the total body and renal clearances of inulin were investigated in a total of 37 healthy adult volunteers and 10 patients with stable chronic renal failure after the single intravenous injection of a dose of 70 mg/kg given over 5 min. 2. The elimination of inulin was highly concentration-dependent, and in healthy volunteers the renal clearance fell from 103.7 +/- 14.4 ml min-1 1.73 m-2 during the first hour after administration to 49.1 +/- 20.9 ml min-1 1.73 m-2 over the period 6-8 h. In the patients with renal failure the renal clearance fell correspondingly from 39.7 +/- 16.5 to 26.6 +/- 8.6 ml min-1 1.73 m-2. There were no changes in the simultaneously measured clearances of creatinine. 3. The values obtained for the total body clearance of inulin after a single injection depend critically on dose, the number and timing of blood samples, the choice of pharmacokinetic model, the number of data points chosen for estimation of the slope of the terminal elimination phase for analysis by the methods of residuals, and the weighting used for curve fitting by non-linear regression analysis. 4. With standardized conditions of sampling from 0 to 2 h and weighted non-linear regression analysis of the plasma concentration-time data, the total body and renal clearances of inulin were almost identical in subjects with normal renal function at 105.2 +/- 10.2 and 102.9 +/- 13.0 ml min-1 1.73 m-2. In the patients with chronic renal failure sampling was continued for 3 h and the corresponding clearances were 40.4 +/- 15.3 and 38.9 +/- 15.7 ml min-1 1.73 m-2. 5. The 0-2 h total body and renal clearances of inulin were measured by the single injection method and the renal clearance was measured by the standard constant infusion method on different occasions in 10 healthy volunteers. The respective clearances were similar at 101.4 +/- 6.6, 94.9 +/- 11.9 and 88.4 +/- 12.1 ml min-1 1.73 m-2. 6. The reproducibility of the single injection and constant infusion methods was compared by measuring the inulin clearance with both techniques on three occasions in separate groups of eight and nine healthy volunteers. The mean coefficient of variation for the total body clearance with the single injection method was only 3.9% compared with 9.5% for the renal clearance determined the same way and 12.0% for the renal clearance during constant infusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1996

Hemodynamic responses to intravascular injection of epinephrine-containing epidural test doses in adults during general anesthesia.

BACKGROUND: Epidural anesthesia is sometimes initiated during general anesthesia, yet few data exist concerning efficacy of epinephrine-containing test doses. METHODS: Thirty-six patients were randomized to receive either 0.5 MAC isoflurane, 1 MAC isoflurane, or 0.5 MAC each (1 MAC total) of isoflurane and nitrous oxide. Each subject received intravenous saline followed by three test doses containing 45 mg lidocaine with 7.5, 15, and 30 micrograms epinephrine in a randomized, double-blind fashion. Heart rate and systolic, diastolic, and mean blood pressures were measured for 5 min after injection. Positive hemodynamic criteria identifying intravascular injection were determined from peak increases in hemodynamics during administration of saline. Dose-effect relationships between epinephrine and peak increases in hemodynamics were assessed with linear regression. Minimum required doses of epinephrine to produce peak positive hemodynamic increases on average were determined from linear regression. RESULTS: Positive hemodynamic criteria were identified as increases in heart rate > or = 8 beats/min, systolic blood pressure > or = 13 mmHg, diastolic blood pressure > or = 7 mmHg, and mean blood pressure > or = 9 mmHg. Significant dose-effect relationships were observed for epinephrine and peak increases in hemodynamics (correlation coefficients ranged from 0.61-0.91). Minimum required doses of epinephrine ranged from 6 to 19 micrograms depending on hemodynamic measurement and anesthetic group. CONCLUSIONS: Hemodynamic responses to intravascular injection of test doses vary with dose of epinephrine and depth and type of general anesthetic used. Thus, the 15 micrograms epinephrine contained in the standard test dose may not be sufficient during all anesthetic conditions.

Adult↗