Der Anaesthesist
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Randomized Controlled Trial Clinical Trial
[Variation in inspiratory gas flow in pressure support ventilation. The effect on respiratory mechanics and respiratory work].
During pressure support ventilation (PSV), the timing of the breathing cycle is mainly controlled by the patient. Therefore, the delivered flow pattern during PSV might be better synchronised with the patient's demands than during volume-assisted ventilation. In several modern ventilators, inspiration is terminated when the inspiratory flow decreases to 25% of the initial peak value. However, this timing algorithm might cause premature inspiration termination if the initial peak flow is high. This could result not only in an increased risk of dyssynchronization between the patient and the ventilator, but also in reduced ventilatory support. On the other hand, a decreased peak flow might inappropriately increase the patient's inspiratory effort. The aim of our study was to evaluate the influence of the variation of the initial peak-flow rate during PSV on respiratory pattern and mechanical work of breathing. ⋯ COPD patients had significantly higher pressure support than control patients. With decreasing inspiratory flow, Wpi increased significantly in COPD patients.(ABSTRACT TRUNCATED)
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Comparative Study Clinical Trial
[Cardiac output determination with transpulmonary thermodilution. An alternative to pulmonary catheterization?].
Cardiac output measurements are often helpful in the management of critically ill patients and high risk-patients. In this study an alternative technique for measurement of cardiac output by the transpulmonary indicator dilution technique (TPID) was evaluated in comparison to conventional thermodilution using a pulmonary artery catheter. With TPID, a thermistor-tipped catheter (the smallest available is 1.3 F) is placed in the aorta via a femoral artery introducer. Thus, TPID can also be used in very small children in whom placement of a pulmonary artery catheter may be difficult or even impossible. In principle, TPID is less invasive since the possible complications of the pulmonary catheters are avoided. We investigated the accuracy and reproducibility of transpulmonary thermodilution in patients over a broad range in age and body surface. ⋯ The amplitude of the typical arterial thermodilution curve shows a smaller and more delayed course than the pulmonary artery thermodilution curve. There was a very good correlation between the values found by pulmonary and TPID cardiac output measurements (R = 0.968). There was a slightly smaller cardiac output value measured by the TPID (Bias = -4.7 +/- 1.5% sem) The reproducibility of duplicate measurements with the two methods were nearly the same, the standard deviation of the difference was 10.9% for the pulmonary thermodilution method and 11.7% for TPID. DISCUSSION. TPID gives an alternative technique for measurement of cardiac output. We showed over a broad range in age and body surface a very good correlation with thermodilution measurements in the pulmonary artery. The slightly smaller values for TPID are explained by early recirculation, for clinical purposes the difference is negligible. However, the reproducibility of a method is clinically very important. Both methods showed in duplicate measurements basically the same reproducibility. The disadvantage of TPID in being more sensitive to baseline alteration is counterbalanced by less respiratory variability in comparison to the conventional thermodilution technique. However, by increasing the amount of injected indicator (i.e., 0.2 ml/kg approximately equal to 15 ml in an adult) it is possible to reduce the effect of baseline alteration. By using fiberoptic catheters it is even possible to use TPID as double-indicator dilution technique to measure intrathoracic blood volume (ITBV) and extravascular lung water (EVLW). We conclude that in many patients TPID might be an attractive, less invasive and reliable alternative to conventional cardiac output measurement by pulmonary artery catheter.
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Pain is a major, but largely neglected problem in AIDS patients. The aim of this article is to review the etiology of pain manifestations in AIDS patients in different organ systems and to discuss appropriate treatment strategies. The most common pain symptoms in AIDS patients are headache, oral cavity pain, dysphagia and adynophagia, chest pain, abdominal pain and pain related to peripheral neuropathy. ⋯ In view of the multiple organs involved in the presentation of AIDS requiring multiple drugs, careful attention to side effects, contraindications and drug interactions is warranted, when administering pain medications. Fear of the complexity of these issues should, however, not prevent effective pain management for these patients, who suffer from a fatal disease. A multidisciplinary approach to pain in AIDS patients, similar to the approach in patients with cancer, is desirable.
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Comparative Study Clinical Trial
[Infrared temperature measurement in the ear canal with the DIATEK 9000 Instatemp and the DIATEK 9000 Thermoguide. Comparison with methods of temperature measurement in other body parts].
Temperature of the tympanic membrane is recommended as a "gold standard" of core-temperature recording. However, use of temperature probes in the auditory canal may lead to damage of tympanic membrane. Temperature measurement in the auditory canal with infrared thermometry does not pose this risk. Furthermore it is easy to perform and not very time-consuming. For this reason infrared thermometry of the auditory canal is becoming increasingly popular in clinical practice. We evaluated two infrared thermometers-the Diatek 9000 Thermoguide and the Diatek 9000 Instatemp-regarding factors influencing agreement with conventional tympanic temperature measurement and other core-temperature recording sites. In addition, we systematically evaluated user dependent factors that influence the agreement with the tympanic temperature. ⋯ Although easy to use, infrared thermometry requires careful handling. To obtain optimal recordings, the time between two consecutive readings should not be less than two min. Recordings should be taken immediately after positioning the devices in the auditory canal. Best results are obtained in the 60 degrees position with the grip of the devices following the ramus mandibulae (telephone handle position). The lower readings of infrared thermometry compared with tympanic contact probes indicate that the readings obtained represent the temperature of the auditory canal rather than of the tympanic membrane itself. To compensate for underestimation of core temperature by infrared thermometry, the results obtained are corrected and transferred into core-equivalent temperatures. This data correction reduces mean differences between infrared recordings and traditional core-temperature monitoring, but leaves limits of agreement between the two methods uninfluenced.
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Total intravenous anaesthesia with ketamine-propofol offers distinct advantages over a TIVA with an opiate, including less cardiovascular and respiratory depression and an altered neuroendocrine and immunological stress response pattern. The effects of the more active stereoisomer S-(+)-ketamine in combination with propofol on the circulatory, endocrine and metabolic responses to abdominal surgery were compared with those of alfentanil-propofol. Twenty-four patients scheduled for elective hysterectomy participated in this study which had the approval of our institution's ethics committee. ⋯ The initial ketamine bolus and tracheal intubation caused a marked, transient increase of mean arterial blood pressure from the baseline value of 105 mmHg to 120 mmHg with a subsequent decrease to 88 mmHg prior to skin incision and a gradual return to baseline during surgery. TIVA with ketamine-propofol had little effect on the perioperative courses of the endocrine parameters, which behaved as they do under anesthesia with isoflurane-nitrous oxide. Plasma catecholamine concentrations were not elevated in the period between induction of anaesthesia and skin incision.