No abstract available.
Carotid Arteries* ; Humans ; Stents*

BACKGROUND: Induction of general anesthesia in patients with cardiac disease must guarantee hemodynamic stability and should result in a satisfactory anesthetic level. The purpose of this study was to analyze the hemodynamic effects of midazolam/sufentanil in comparison with etomidate/sufentanil used for induction of anesthesia in patients with cardiac disease. METHODS: All the patients (n = 30) in the study were about to undergo cardiac surgery and were divided into the midazolam group (n = 15) and etomidate group (n = 15). The induction dose of midazolam was 0.18 mg/kg, etomidate 0.3 mg/kg, vecuronium 0.15 mg/kg, sufentanil 3 microgram/kg, hemodynamics and oxygenation were recorded in the awake state (pre-induction), and 10 minutes after intubation (post-intubation). RESULTS: The etomidate group had a shorter time of anesthetic induction, and some myoclonic movement (13%) was observed. After intubation, reductions of heart rate (13.8%), mean arterial pressure (18.4%), cardiac index (14.8%), left ventricular stroke work index (9.7 - 38.5%), oxygen delivery index (7.43%), oxygen consumption index (10.3%), and Qs/Qt (25.6%), and an increase in central venous pressure (0 - 50%) were observed in both groups. Decreases in right ventricular stroke work index and mean arterial pressure were observed in the midazolam group, but no change in right ventricular stroke work index and a decrease in mean arterial pressure was observed in the etomidate group. In the midazolam group the values of right ventricular stroke work index and mean arterial pressure were significantly lower than in the etomidate group. The heart rate of the midazolam group in patients with CABG were significantly lower than in the etomidate group. CONCLUSIONS: The results of this study shows that etomidate was found to be as reliable and effective an agent for induction as midazolam.
Anesthesia* ; Anesthesia, General ; Arterial Pressure ; Central Venous Pressure ; Etomidate ; Heart Diseases* ; Heart Rate ; Hemodynamics ; Humans ; Intubation ; Midazolam ; Oxygen ; Oxygen Consumption ; Stroke ; Sufentanil ; Thoracic Surgery ; Vecuronium Bromide

BACKGROUND: Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance. METHODS: Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 ml/cmH₂O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 ml/cmH₂O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments. RESULTS: The mean ± standard deviation ratio of volumes distributed to each lung (VL1/VL2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH₂O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, and 0.95 cmH₂O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, and 1.41 cmH₂O) in the C120 group, compared to ID 8 mm (P < 0.05). CONCLUSIONS: In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.
Airway Obstruction ; Compliance ; Lung Compliance* ; Lung* ; Positive-Pressure Respiration ; Positive-Pressure Respiration, Intrinsic ; Respiration, Artificial ; Tidal Volume ; Trachea ; Ventilation

Pharmacokinetics is the study of the rate and degree of drug transport to various tissues in the human body. Pharmacokinetic parameters summarize drug kinetics and ideally predict a clinical situation. A single kinetic profile may be summarized by peak concentration, peak time, half-life and area under the curve. Dosage regimens are designed to confer the maximum desired effects for the required time period with minimal toxicity. Target-controlled infusions use pharmacokinetic models to titrate intravenous anesthetic administration to achieve a desired drug concentration. Context-sensitive half time is used to predict the clinical time course, rather than terminal half-life. It is important that anesthesiologists understand the basic pharmacological principles and apply them in their daily clinical practice. This review discusses the ways in which anesthesiologists can design a patient-specific dosage regimen of intravenous anesthetics by utilizing basic concepts of pharmacokinetics and pharmacodynamics using pharmacokinetic simulations.
Anesthetics, Intravenous ; Half-Life ; Human Body ; Pharmacokinetics*

No abstract available.
Bilirubin* ; Humans ; Infant, Newborn*

BACKGROUND: The doses of muscle relaxants used to facilitate tracheal intubation are 2 x ED(96). However, the potency needs to be measured on a molar basis rather than by the mass of the drug. The aim of this study was to compare the pharmacodynamics and intubation conditions of the muscle relaxants using a continuous infusion during induction. METHODS: The time courses of the drug response and tracheal intubating conditions of the muscle relaxants by a continuous infusion were examined in 44 patients undergoing elective surgery. The neuromuscular effects of the relaxants were quantified by recording the twitch response of the adductor pollicis muscle after stimulating the ulnar nerve (0.1 Hz, 0.2 ms, supramaximal stimuli). The onset time and duration of each group were measured and the dose-response curves were determined by logistic regression analysis. RESULTS: The doses (micromol/kg) for intubation were 1.08 +/- 0.31 of rocuronium, 0.58 +/- 0.10 of atracurium, 0.28 +/- 0.06 of vecuronium and 1.36 +/- 0.65 of succinylcholine. The relative potency of rocuronium, atracurium, vecuronium and succinylcholine was 1.00 : 1.86 : 3.86 : 0.79. There were no significant differences between any of the groups with regard to the onset time of the relaxants. The duration of the relaxants was succinylcholine (4 min 12 s), rocuronium (25 min 36 s), atracurium (34 min 28 s), and vecuronium (42 min 24 s). The intubation conditions of the succinylcholine group were inferior to those of the vecuronium group. CONCLUSIONS: This method can be used to determine the potency and pharmacodynamics between the neuromuscular blockers. Further study will be needed to confirm these results and to evaluate the effect of the infusion rate on this model.
Atracurium ; Humans ; Intubation* ; Logistic Models ; Molar ; Neuromuscular Agents ; Neuromuscular Blockade ; Neuromuscular Blocking Agents ; Succinylcholine ; Ulnar Nerve ; Vecuronium Bromide

PURPOSE: The reliability of test is determined by each items' characteristics. Item analysis is achieved by classical test theory and item response theory. The purpose of the study was to compare the discrimination indices with item response theory using the Rasch model. METHODS: Thirty-one 4th-year medical school students participated in the clinical course written examination, which included 22 A-type items and 3 R-type items. Point biserial correlation coefficient (C(pbs)) was compared to method of extreme group (D), biserial correlation coefficient (C(bs)), item-total correlation coefficient (C(it)), and corrected item-total correlation coeffcient (C(cit)). Rasch model was applied to estimate item difficulty and examinee's ability and to calculate item fit statistics using joint maximum likelihood. RESULTS: Explanatory power (r2) of Cpbs is decreased in the following order: C(cit) (1.00), C(it) (0.99), C(bs) (0.94), and D (0.45). The ranges of difficulty logit and standard error and ability logit and standard error were -0.82 to 0.80 and 0.37 to 0.76, -3.69 to 3.19 and 0.45 to 1.03, respectively. Item 9 and 23 have outfit > or =1.3. Student 1, 5, 7, 18, 26, 30, and 32 have fit > or =1.3. CONCLUSION: C(pbs), C(cit), and C(it) are good discrimination parameters. Rasch model can estimate item difficulty parameter and examinee's ability parameter with standard error. The fit statistics can identify bad items and unpredictable examinee's responses.
Discrimination (Psychology) ; Humans ; Joints ; Schools, Medical

Major surgeries such as total hip arthroplasty are likely to be associated with high incidences of perioperative morbidity and mortality, which may be compounded by the increased risk of heavy bleeding. It has been reported that these complications may occur more commonly when general, rather than spinal anesthesia is used. This study was undertaken to investigate whether spinal anesthesia is clinically safer than general anesthesia undergoing total hip arthroplasty. Forty-one patients were classified randomly into 2 groups to compare the effects of spinal versus general anesthesia on blood pressure, pulse rate, amounts of blood loss and transfusion, and complications in total hip arthroplasty. In general anesthesia groups, systolic blood pressure significantly increased from the baseline of 125.6+/-14.4 mmHg to 137.2+/-12.7 mmHg at 10 minutes post-induction (p<0.05). Pulse rate also increased from the baseline of 75.2+/-1.6 beats/min to 90.3+/-8.0 beats/min at 10 minutes post- induction. In spinal anesthesia group, systolic blood pressure significantly decreased from the baseline of 121.5+/-11.5 mmHg to 113.4+/-15.8 mmHg at 10 minutes post-induction (p<0.05). Pulse rate also decreased from the baseline 78.6+/-11.9 beats/min to 74.2+/-5.2 beats/min at 10 minutes post-induction. After 10 minutes post-induction, systolic blood pressure and pulse rate became stable in both groups. The amount of intraoperative blood loss was less in spinal anesthesia group (510+/-140 ml) than in the g anesthesia group (720+/-150 ml). However, difference in the amount of blood transfused was not significant in the two groups. Postoperative hemoglobin values showed a marked decreases in both group. The complication rates were similar in both groups. It appears that blood loss during total bip arthroplasty is less in the spinal than general anesthesia group. However, other clinical variables investigated are not significantly different in the two groups.
Anesthesia ; Anesthesia, General* ; Anesthesia, Spinal* ; Arthroplasty ; Arthroplasty, Replacement, Hip* ; Blood Pressure ; Heart Rate ; Hemorrhage ; Humans ; Incidence ; Mortality

BACKGROUND: Baricity of the local anesthetics is a major determinant of the distribution of local anesthetics in CSF. The purpose of this study was to assess the value of refractometry in measuring the specific gravity of CSF, local anesthetics and adding solutions, and then comparing these to the density of CSF and local anesthetics. METHODS: CSF samples were obtained from 30 patients during spinal anesthesia. 0.5% hyperbaric tetracaines were diluted with CSF to create a 1:1 to 1:10 density and specific gravity measurements were made at room temperature, using a refractometer. 2% lidocaine was diluted with distilled water, normal saline, 5% and 10% dextrose water to create 2%, 1%, 0.67%, 0.5% and 0% mixtures measured respectively. RESULTS: Specific gravity of CSF was 1.0066 +/- 0.0006 and SG of 0.5% tetracaine was 1.0285 +/- 0.0028. The effect of specific gravity on the concentrations of tetracaine was determined by linear regression with r = 0.9803, y = 1.0060 + 0.0440 X x. Dilutions of 2% lidocaine with adding solutions were distilled water, y = 1.0008 + 0.0078 X x ; normal saline, y = 1.0056 + 0.0053 X x ; 5% dextrose, y = 1.0208 - 0.0022 X x ; and 10% dextrose, y = 1.0436 - 0.0135 X x. CONCLUSIONS: The relationship between concentration and specific gravity of local anesthetics is linear. We conclude that refractometry is a reliable method to predict density of local anesthetics.
Anesthesia, Spinal ; Anesthetics, Local* ; Glucose ; Humans ; Lidocaine ; Linear Models ; Refractometry* ; Specific Gravity ; Tetracaine ; Water

BACKGROUND: Impedance Cardiography is a noninvasive and simple method of cardiac output determination. The purpose of this study was to compare an impedance device with the thermodilution method during the intraoperative period in patients undergoing open heart surgery. METHODS: The study was undertaken in 12 patients undergoing elective open heart surgery without a shunt. When abnormal impedance signals were obtained, the patients were not included in the analysis. Stroke volume was calculated according to the formula of Bernstein. Cardiac output was measured simultaneously by the impedance cardiograph and thermodilution method. We obtained 41-paired measurements during the surgical procedure. The method described by Bland and Altman and linear regression analysis were used for comparison. RESULTS: The correlation coefficient between the two methods was r = 0.36 (P<0.05). Bias and precision analysis between the two techniques showed a mean difference between techniques of 0.80 L/min and a SD of the differences of 1.71 L/min (95% level of agreement 4.21 L/min to -2.62 L/min). Trending analysis showed the impedance cardiogram to inaccurately track the direction of thermodilution CO changes and to underestimate their magnitude (r = 0.57, intercept -3.29, slope 1.27). CONCLUSIONS: This study reveals clinically significant errors in impedance CO measurements. These inaccuracies may be related to the intraoperative environment and abnormal cardiovascular function. Further investigation of such techniques to improve the performance of the impedance cardiogram in the intraoperative setting is warranted.
Bias (Epidemiology) ; Cardiac Output* ; Cardiography, Impedance* ; Electric Impedance* ; Heart* ; Humans ; Intraoperative Period ; Linear Models ; Stroke Volume ; Thermodilution* ; Thoracic Surgery*