Adaptation of non-linear mixed amount with zero amount response surface model for analysis of concentration-dependent synergism and safety with midazolam, alfentanil, and propofol sedation.

BACKGROUND: The non-linear mixed amount with zero amounts response surface model can be used to describe drug interactions and predict loss of response to noxious stimuli and respiratory depression. We aimed to determine whether this response surface model could be used to model sedation with the triple drug combination of midazolam, alfentanil and propofol. METHODS: Sedation was monitored in 56 patients undergoing gastrointestinal endoscopy (modelling group) using modified alertness/sedation scores. A total of 227 combinations of effect-site concentrations were derived from pharmacokinetic models. Accuracy and the area under the receiver operating characteristic curve were calculated. Accuracy was defined as an absolute difference <0.5 between the binary patient responses and the predicted probability of loss of responsiveness. Validation was performed with a separate group (validation group) of 47 patients. RESULTS: Effect-site concentration ranged from 0 to 108 ng ml-1 for midazolam, 0-156 ng ml-1 for alfentanil, and 0-2.6 µg ml-1 for propofol in both groups. Synergy was strongest with midazolam and alfentanil (24.3% decrease in U50, concentration for half maximal drug effect). Adding propofol, a third drug, offered little additional synergy (25.8% decrease in U50). Two patients (3%) experienced respiratory depression. Model accuracy was 83% and 76%, area under the curve was 0.87 and 0.80 for the modelling and validation group, respectively. CONCLUSION: The non-linear mixed amount with zero amounts triple interaction response surface model predicts patient sedation responses during endoscopy with combinations of midazolam, alfentanil, or propofol that fall within clinical use. Our model also suggests a safety margin of alfentanil fraction <0.12 that avoids respiratory depression after loss of responsiveness.

A randomised trial comparing real-time double-lumen endobronchial tube placement with the Disposcope® with conventional blind placement.

Double-lumen endobronchial tube placement is challenging. This study compared double-lumen tube placement with the Disposcope® , a wireless videostylet allowing real-time visualisation, with conventional blind placement. Patients undergoing elective thoracic surgery with normal airways requiring one-lung ventilation were randomly allocated into two groups (27 patients in each group). The Disposcope was used to assist left-sided double-lumen tube placement in one group, and conventional blind placement was performed in the control group. Placement in both groups was checked with fibreoptic bronchoscopy. The Disposcope-assisted group had a shorter total mean (SD) placement time (18.6 (2.5) s vs. 21.4 (2.9) s, p < 0.001), laryngoscopy to end of auscultation time (83.4 (3.0) s vs. 93.9 (5.7) s, p < 0.001) and total operation time (130.7 (6.1) s vs. 154.5 (6.3) s, p < 0.001). In the Disposcope-assisted group, the double-lumen tube was inserted in the correct side in all patients (100.0%), whereas in the conventional group, the double-lumen tube was placed in the correct side in 25 (92.6%) patients and in the wrong side in 2 (7.4%) patients; the difference was not significant (p = 0.150). In the Disposcope-assisted group, the double-lumen tube was inserted to the optimal depth in 24 (88.9%) patients, whereas in the conventional group it was inserted to the optimal depth in one (4.0%) patient. The Disposcope increased the success rate of double-lumen tube placement, and shortened the total operation time when compared with standard placement with confirmation using fibreoptic bronchoscopy, and may replace the conventional method.

Catheter-related right internal jugular vein thrombosis after chest surgery.

BACKGROUND: Central venous catheters (CVCs) are frequently used for monitoring haemodynamic status and rapidly delivering fluid therapy during the peri- and postoperative periods. Indwelling CVCs are typically used 7-14 days postoperatively for additional monitoring and treatment, but patients may develop asymptomatic catheter-related thrombosis, leading to life-threatening pulmonary embolism and death. Early detection helps to avoid such complications. METHODS: This prospective observational study investigated the risk factors associated with catheter-related right internal jugular vein thrombosis in patients undergoing chest surgery. The study enrolled 24 patients who were scheduled to receive chest surgeries during which catheters were needed. To detect thrombus formation, Doppler ultrasound examinations from the thyroid cartilage level to the supraclavicular region were used after CVC placement and on each of the following days until the catheter was removed. RESULTS: No thrombosis was found in patients before surgery, but it appeared in 75% (18/24) after surgery. The risks of thrombosis increased with a longer duration of anaesthesia, greater amounts of bleeding, and use of postoperative ventilator support. CONCLUSIONS: Earlier catheter removal may reduce the risk of catheter-related thrombosis and avoid possibly fatal complications after catheter-related thrombosis.

Discriminant analysis for anaesthetic decision-making: an intelligent recognition system for epidural needle insertion.

BACKGROUND: Incorrect placement of epidural catheters causes medical complications. We used linear discriminant analysis (LDA) to develop an intelligent recognition system (i-RS) in order to guide epidural placement and reduce physician error. METHODS: We analysed real-time dual-wavelength fibreoptic data recorded from the end of an epidural needle in a live porcine model. Two categories of tissue layers were necessary for correct placement of catheter: epidural space and ligamentum flavum. The data were tested using linear, quadratic and logistic parametric analysis to identify which method could distinguish the two anatomical structures. RESULTS: LDA was the best fit for our model. There was ∼80% sensitivity and specificity for correct anatomical identification. Error rates based on cross-validation were 17.0% for the epidural space and 18.6% for ligamentum flavum. Error rates were greater with the 532 nm compared with 650 nm wavelength. CONCLUSIONS: The sensitivity and specificity of LDA for identifying the correct anatomical structure was similar to a physician who is an expert in epidural placement. Overall performance of an i-RS could be improved by expanding the database for decision-making and adding a category of uncertainty. This would reduce complications caused by incorrect epidural placement.

The quality of life among coronary heart disease patients at a teaching hospital.

BACKGROUND AND AIMS: Quality of life after acute coronary heart disease amongst patients is important outcome factor in deliberations of patient's care. The main aim of the study was to examine the quality of life amongst acute CHD patients. MATERIALS AND METHODS: A cross sectional descriptive study was conducted after an acute attack amongst coronary heart disease (CHD) patients in Universiti Kebangsaan Malaysia Medical Centre (UKMMC).The Medical Outcomes Short Form 36 (SF-36) comprised of 36 items used to measure quality of life which comprised of 4 domains of physical component summary were physical function, role physical, bodily pain, and general health and 4 domains of mental component summary were vitality, social function, emotional role, and mental health. A total of 108 respondents were recruited for this study. RESULTS: The findings showed that CHD. Respondents possessed good level of quality of life with total score of (59 ± 22). The total score of physical domain had mean and SD of 56 ± 24, while the total scores of the mental domain had mean and SD of 62 ± 27. There were significant differences between the general health components of quality of life with educational status of the CHD patients with (F= 5.433, p<0.05). There were significant differences in role physical components of quality of life with income (F= 3.144, p<0.05). CONCLUSION: The cardiac rehabilitation program would have deliberately improved their needs and conditions whilst hospitalization. These results have implications in which CHD patients should be evaluated with regard to their continuity of care.

Thermal symmetry of skin temperature: normative data of normal subjects in Taiwan.

BACKGROUND: The aims of this study were (a) to establish normative data of thermal symmetry (left vs. right) in normal subjects; (b) to compare the skin temperature in various regions between young and old people in Taiwan and between male and female. METHODS: The skin surface of 57 healthy volunteers (aged 24 to 80 yr) was divided into 25 areas and measured by an infrared thermography (Avionics TVS-2000, Japan). The average temperatures of these 25 regions were compared: (a) left vs. right side, (b) young (< or = 60 yr, n = 37) vs. old (> 60 yr, n = 20), and (c) male vs. female. Student's t-test was used to assess means between both groups. RESULTS: The neck carried the highest skin temperature (31.9 degrees C +/- 0.6; mean +/- SD) of the body in comparison with the toes that had the lowest one (27.5 degrees C +/- 2.0). The side-to-side temperature differences were subtle, which did not exceed 0.5 degrees C. The average skin temperature of elderly was slightly lower than that of young subjects in 11 out of 25 areas (p < 0.05), especially the distal parts of extremities. Elderly female had lower skin temperature in various truncal areas as compared with their counterpart. However, the skin temperature was higher in the distal extremity (p < 0.05). CONCLUSIONS: The thermoregulatory system is substantially symmetrical. The result of this study offered valuable normative database on skin thermal symmetry in normal population of Taiwan, and may be useful as a diagnostic aid in patients with various states of disorders associated with autonomic dysfunctions.

Repeated attacks of venous air embolism during craniotomy--a case report.

Venous air embolism (VAE) is not uncommon during craniotomy, but repeated attacks of VAE during a single surgical procedure is rarely seen. We report a successful intraoperative management of repeated attacks of air embolism in a patient who sustained craniotomy for intracranial hemorrhage (ICH) in prone position. A 70-year-old male suffering from hemorrhage in the right cerebellar hemisphere with impending brainstem herniation was scheduled for craniotomy. He had history of hypertension but it was not well controlled with medical treatment. Emergent craniotomy for removal of blood clot resulting from ICH was performed. During the operation, sudden decrease of end-tidal CO2 (EtCO2) level, fall of blood pressure and increase of central venous pressure (CVP) were noted. Since air bubbles were retrieved from CVP catheter venous air embolism was highly suspected. With prompt diagnosis and proper management, we successfully improved the patient's hemodynamic status and he was discharged without any sequelae. Early detection together with aggressive treatment is the only way in the management of intraoperative venous air embolism.

Reversal of mivacurium chloride: edrophonium of spontaneous recovery in microscopic laryngeal surgery.

BACKGROUND: A double-blind, randomized study was designed to compare the recovery manner of mivacurium infusion with or without edrophonium reversal in microscopic laryngeal surgery. Neuromuscular blockade was quantified using the train-of-four stimuli to the ulnar nerve and quantification of the ratio of the fourth twitch to the first twitch. METHODS: With the approval of the Human Studies Committee of the Taipei Veterans General Hospital and patient informed consent, 40 healthy (ASA I or II) patients with age from 24 to 54 years, undergoing microscopic laryngeal surgery were randomly selected for study. Mivacurium chloride 0.2 mg/kg was given intravenously, and then it was given in continuous infusion to maintain muscle relaxation at 90% twitch block during the procedure. At the end of operation, mivacurium infusion was terminated. In a double-blind manner, group I patients (n = 20) received intravenous edrophonium 1 mg/kg and atropine 0.01 mg/kg for reversal when T1 was at 10% recovery whereas patients in Group II (n = 20) received placebo in the same manner. Mean infusion rate, recovery index (RI50, time from T1 25% to T1 50%; RI75, time from T1 25% to T1 75%), extubation time, and discharge time between groups were compared. Nausea, vomiting, and dysrhythmias were also documented until the patient was discharged from hospital. RESULTS: The demographic data between two groups were similar. The recovery index (RI75) for group I was shorter than that of placebo group (5.3 +/- 2.19 min vs. 7.3 +/- 0.9 min) and the difference was statistically significant (P = 0.017). There were no statistically significant differences in mean infusion rate, incidence of nausea and vomiting, and discharge time from the POR. The incidence of tachycardia or arrhythmia in group I was significantly greater than that in group placebo. CONCLUSIONS: Mivacurium, a short-acting nondepolarizing agent, is a suitable muscle relaxant for patients receiving microscopic laryngeal surgery. Recovery time with the use of edrophonium as reversal agent was shorter than with placebo, but extubation and discharge time did not differ in two groups. The time which could be saved by the use of edrophonium for reversal of mivacurium to hasten the maximal recovery appears to be less than a few minutes. Therefore, clinically, the value of routine use of edrophonium to obtain a faster recovery does not outweigh its demerits of cost and risk and is not worthy of recommendation.

Effect of milrinone on postbypass pulmonary hypertension in children after tetralogy of Fallot repair.

BACKGROUND: Postbypass pulmonary hypertension in surgical correction of tetralogy of Fallot (TOF) is a risk for right ventricular failure. Effective management remains a major challenge. Milrinone is a new drug with a unique mechanism of "inodilation", which offers both inotropic and vasodilatory effects. We attempted to determine if application of milrinone could improve cardiopulmonary dysfunction in children after TOF repair. METHODS: We studied 10 children with postbypass pulmonary hypertension after TOF repair within six months. Heart rate, systolic pulmonary arterial pressure (PAP), systolic arterial blood pressure (SBP), pulmonary capillary wedge pressure and PAP/SBP ratio were recorded. Standard cardiopulmonary bypass (CPB) was performed. After CPB, if PAP/SBP was more than 0.5, pulmonary hypertension was suspected and milrinone was administered with a loading dose of 20 micrograms/kg followed by continuous infusion of 0.2 microgram/kg/minute. Hemodynamics were compared before and after administration of milrinone to evaluate its effect. RESULTS: significant reduction in PAP/SBP ratio within 15 minutes was found after administration of milrinone. The effect persisted for 24 hours during continuous infusion of milrinone. No remarkable adverse effect was noted in the study. CONCLUSIONS: We conclude that milrinone is effective in the management of pulmonary hypertension following CPB in children who underwent TOF repair.

Anesthetic managements of the patients with giant mediastinal tumors--a report of two cases.

Anesthesia for patients with a huge anterior mediastinal tumor is a well-known challenge and trial to all the anesthesiologists. The tumor mass which directly compresses the trachea and bronchus induces hypoxia and asphyxia, eventuating in cardiac arrest or even fatality in the process of general anesthesia. In selection of anesthetic technique, general anesthesia is deliberately avoided if not mandatory or spontaneous respiration should be strictly preserved by all means if obligatory. Our surgical colleagues are usually not so familiar with this potentially life-threatening situation as are the anesthesiologists, and bad communications and interactions between the two may court disaster. Here we reported 2 cases: the former was an immediate mortality in a youth with a giant anterior mediastinal tumor undergoing excisional biopsy of a neck mass under general anesthesia, and the latter was a successful anesthetic management in a woman with a giant mediastinal tumor receiving abdominal total hysterectomy for cervical cancer in situ under spinal anesthesia. The hazards of general anesthesia in these patients and the importance of comprehending preanesthetic preparations were reviewed and discussed. Moreover, we address that whenever one has shot his bolt still futile to improve the respiratory crisis in a case with mediastinal tumor, try to ventilate the patient in a prone position as it has clinical importance in ventilation and oxygenation.

A long-term immunological study of childhood onset systemic lupus erythematosus.

Immunological dysregulation is an important cause of the development of systemic lupus erythematosus (SLE). Serological evaluation has been useful in the clinical management of patients and as a prognostic indicator. Sixteen patients who developed SLE as children were followed up for more than three years and immunological data collected. The results showed that (a) complement C3 concentration was lower in the active stage of SLE, especially during a major clinical exacerbation, but rarely preceded a major flare up. The concentration was often normal during the mildly to moderately active stage. In contrast, a low complement C4 concentration often preceded a major clinical exacerbation and could be of longer duration, sometimes persisting regardless of disease activity. (b) A T cell subset distribution study showed persistently low CD4 positive T cells in the peripheral blood of patients with SLE during the long term follow up, strongly suggesting that the intrinsic defect is mainly localised in T helper/inducer cells. These abnormal cellular defects did not tend to return to normal even in long term remission. (c) The persistently higher serum interleukin 2 and interleukin 2 receptor concentrations in SLE strongly suggested that the T cells were preactivated in vivo and that these phenomena might persist even in remission. (d) The best single parameter for predicting active SLE was anti-dsDNA. It was highly correlated with disease activity in most patients, and the asymptomatic increase of anti-dsDNA (greater than or equal to 60 U/ml, radioimmunoassay) was often followed by a major clinical exacerbation, especially in patients with a simultaneously low complement C4 concentration, suggesting that it might be an important warning sign of a major flare up. High dose steroids are indicated in this group of patients.

[A comparative study of epinephrine injection and beta 2-agonist inhalation in the treatment of childhood asthma].

A total of 29 cases were enrolled in this study and divided randomly into Group I (traditional epinephrine injection) and Group II (terbutaline nebulizer inhalation). If patients did not respond well to the initial therapy. a crossover therapeutic regimen was assigned and their pulmonary function, peak expiratory flow rate (PEFR) was measured every 10 minutes for half an hour. Both groups of patients revealed significant improvement post initial treatment P less than 0.0001). Within group difference was analysis by Wilcoxon signed rank test. All subgroups at 10 minutes, 20 minutes, and 30 minutes were compared in terms of their baseline pulmonary function, epinephrine group P value showed 0.0059, 0.0038, 0.0025; and terbutaline nebulizer inhalation group P value showed as 0.0007. 0.0003, 0.0003 respectively. An analysis of the group with an initial PEFR below 40% of the normal predicted or the more severely ill childhood acute asthmatic patients, the ten minutes post-treatment PEFR value of the epinephrine group showed P = 0.059; a significant P value of 0.0038 was noted for the terbutaline inhalation group, but both group P value was less than 0.05 at 20.30 minutes post-treatment, respectively. Between-group difference was analysed by Mann Whitney U test. Although all time interval mean data showed higher for the terbutaline inhalation group, statistically it showed P greater than 0.05. The above data suggest terbutaline inhalation therapy at the dosage noted will have early onset of action and better early clinical improvement than the traditional epinephrine injection regimen. There seemed to be no difference in degree of improvement between the two regimens. Observation of crossover treatment found a 50% re-response rate in both group of of patients who did not respond well to their initial regimen, and post crossover treatment PEFR all showed statistically significant improvement. However, still there was no significant difference between the two groups. This suggests that the terbutaline nebulizer inhalation method can not totally replace the more traditional method of acute asthma management, and emphasizes that a crossover therapeutic regimen should be kept in mind because the re-response rate is still encouraging. According to the variance analysis, the most important factor influencing the final outcome was the degree of severity of the initial asthmatic attack. The lower in initial PEFR value. The worse the clinical response. Other factors like age, sex, duration of asthma (year) and time interval between onset to arrival at the emergency room, showed as neither significant nor important.(ABSTRACT TRUNCATED AT 400 WORDS)

Selective IgG subclass deficiencies in patients with recurrent sinopulmonary infections: report of two cases.

Two patients with recurrent sinopulmonary infections and normal total serum immunoglobulin levels were found to have selective deficiencies in IgG subclasses. The serum of one patient contained abnormally low IgG2 and IgG4; and the other was deficient in IgG4. Both patients responded to the treatment with high dose intravenous immunoglobulin. The experiences on these two cases strongly suggest that IgG subclasses should be checked in patients with recurrent sinopulmonary infections in face of normal total immunoglobulins.