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Biomedical subjects

W F List

Publications and source records attributed to W F List.

At least 37 records · Page 2Linked to original sources

Pain treatment in the ICU: intravenous, regional or both?

Adequate treatment of pain in ICU patients should be an integral part of ICU management, as inadequately treated pain leads to a series of complications that may counteract the success of ICU treatment. For continuous intravenous use we recommend sufentanil in a dose of 0.75-1.0 microgram kg-1 h-1 in mechanically ventilated patients and in a dose of 0.25-0.35 microgram kg-1 h-1 in intubated and spontaneously breathing patients. On-demand analgesia, administered via the intravenous or epidural route, may be an alternative to a relatively fixed continuous infusion of an analgesic drug, and in some ICU patients the transdermal use of opioids can be an alternative to continuous intravenous drug application or PCA. Increased sizes of the patch (25, 50, 75, 100 cm2) provide sustained transdermal rates of approximately 25, 50, 75 and 100 micrograms h-1 of fentanyl over a period up to about 72 hours. Patients with trauma to the thorax, pelvic fracture, or after major surgical interventions will be better managed by regional application of analgesic drugs alone or in combination with a systemic analgesic drug infusion. To achieve the best results it is necessary to be well informed and trained in the method, to know the advantages and disadvantages, the correct and modified dosages of the drugs used, and the indications and contraindications.

Administration, Cutaneous↗

Iatrogenic ruptures of the tracheobronchial tree.

We did a retrospective study in 12 patients with iatrogenic tracheal or tracheobronchial ruptures treated since 1975. Ten female subjects, one male subject, and one child (age range, 8 to 72 years), all of whom had undergone intratracheal intubation, were admitted to the hospital. Four patients had been intubated with a double-lumen catheter (two Carlens type with carinal spur, two Robertshaw without spur), and seven had had "high volume-low pressure" tubes, placed under emergency conditions in three of those seven cases. In one further case, an unsuccessful attempt of percutaneous tracheostomy had been made. The localization of the ruptures (all of them longitudinally in the membranaceous wall; length, 2 to 13 cm; mean, 7 cm) comprised both cervical and intrathoracic trachea in seven, the intrathoracic trachea in three instances, and the left main stem bronchus in two cases. Ten patients had mediastinal and subcutaneous emphysema, seven presented with a pneumothorax, and nine had intratracheal bleeding. The interval until the onset of symptoms and diagnoses differed widely: twice diagnoses were made intraoperatively, during thoracic surgery. The longest interval until diagnosis was 5 days; only then did the patient show subcutaneous emphysema and have retrosternal pain. All patients had surgical repair. Nine recovered without sequelae, and three died of septic multiorgan failure.

Adult↗

[Preclinical blood gas analysis. Technical description--initial experiences--indications].

OBJECTIVE: A new portable device for blood gas analyses (BGA) has been examined for prehospital application. METHODS: After a 1 h introduction to the procedure, two physicians used the blood gas analyzer in the emergency medical system in Graz, Austria, for 7 months. The indications for prehospital BGA were prolonged cardiopulmonary resuscitation, mechanical ventilation, hyperventilation for reducing increased intracranial pressure, respiratory failure and metabolic disorders. All patients tested were also checked with pulse oximetry and capnography. TECHNICAL SPECIFICATION: The device measures pO2, pCO2 and pH using the fluorescence method. The innovation of a single-use cassette system makes it unnecessary to do any calibrations or transport any test substances. The storage battery measures eight samples without recharge. The time spent on one measurement is 3-6 min. RESULTS: We took 49 samples from 24 patients and found 16 indications for therapeutical intervention, such as buffering metabolic acidosis and adjusting mechanical ventilation by means of BGA. In all cases the analyzer worked reliably. CONCLUSIONS: One advantage of BGA over the non-invasive methods pulse oximetry and capnography is that it does not interfere with factors like peripheral vasoconstriction or inequality of the pulmonary ventilation/ perfusion ratio. Moreover, it is the only method for controlled buffering of acid-base disturbances. This means more security in diagnostics and therapeutical interventions for the patient in danger of dying. The device has proved to be a useful addition to the monitoring methods for prehospital application.

Acid-Base Equilibrium↗

The inhibition of serotonin evoked bovine coronary artery contraction by halothane, isoflurane and sevoflurane is endothelium-independent.

The present study was designed to determine the direct effects of halothane, isoflurane and sevoflurane on the bovine epicardial coronary artery as well as their mode of action. We chose serotonin as the vasoconstrictor because it also causes endothelium-dependent relaxation of coronary arteries. Isolated spiral strips of bovine epicardial coronary artery with and without endothelium were suspended for isotonic contraction recordings in Tyrode's solution. KCl (80.4 mM) solution induced maximal contraction, regarded as the reference value (100%). The muscle strips were then exposed to increasing concentrations of serotonin from 10(-8) to 10(-4) M in the presence and absence of 1.5 MAC halothane, isoflurane or sevoflurane. All three drugs attenuated serotonin-evoked contraction in the coronary artery strips both those strips with and without endothelium (P < 0.05-0.001). However, there were no significant differences in the attenuation of serotonin-induced contraction of the strips, both with and without endothelium, in each drug group. The attenuation potency of halothane was more than that of isoflurane and sevoflurane. The results demonstrate that halothane, isoflurane and sevoflurane attenuate contractile responses evoked by serotonin in bovine epicardial coronary artery both with and without endothelium.

Anesthetics, Inhalation↗

A comparison of mivacurium infusion requirements between young and elderly adult patients.

Forty-one patients of ASA classes I or II, undergoing elective surgery, were divided into two groups: young, 18-41 years (mean 31), and elderly, 64-79 years (mean 71). The integrated evoked compound electromyogram of the adductor pollicis muscle elicited by stimulation of the ulnar nerve was used to monitor the neuromuscular block of the non-depolarizing muscle relaxant mivacurium. An initial dose of mivacurium 0.15 mg kg-1 allowed six excellent, nine good, three adequate and three poor intubations in the young group, and nine excellent, eight good, three adequate and no poor intubations in the elderly group. Patients recovered until 1-2 stimuli of the train-of-four were visible, and an infusion of mivacurium was started (0.5 mg kg-1 h-1). At 3 min intervals the rate was adjusted by +/- 0.05 mg kg-1 h-1 (+/- 10% initial rate), as indicated during anaesthesia which was provided by nitrous oxide in oxygen, infusion of propofol, and fentanyl supplements. In the first 30 min, the young group had their mivacurium requirement increased to 111.4% (0.56 mg kg-1 h-1), which was reached in the first 15 min, after which it gradually decreased to 92.9% (0.46 mg kg-1 h-1). The elderly group's requirements decreased from the start, to 78.5% (0.39 mg kg-1 h-1). The difference between the two groups was significant (P < 0.05). After the first 30 min, both groups requirements decreased, with time, but with no statistically significant differences.

Adolescent↗

Effects of halothane, isoflurane and sevoflurane on calcium-related contraction in porcine coronary arteries.

BACKGROUND: Volatile anaesthetics have a direct inhibitory effect upon epicardial coronary arterial smooth muscles (1-4). The site and mode of their action at the cellular level need to be clarified, which was the purpose of our study. The present investigation attempted to answer the question in what way volatile anaesthetics influence Ca(2+)-related contraction in isolated porcine epicardial coronary to understand their intracellular mechanism. METHODS: Isolated helical strips of porcine epicardial coronary artery without endothelium were suspended for isotonic contraction recordings in Krebs-Ringer's solution. 9.4 x 10(-2) MK+, 2.5 x 10(-3) M Ca(2+)-induced shortening of the strips was regarded as the reference value (100%). After incubation in Ca(2+)-free solution with 10(-3) M ethlene glycol bis (beta-aminoethyl ether)-N, N-tetraacetic acid (EGTA) for 60 minutes, the muscle strips were exposed to increasing Ca2+ concentrations (10(-4)-10(-2)) either in the presence or absence of 1.5 or 2.5 minimum alveolar concentration (MAC) halothane, isoflurane or sevoflurane, with 9.4 x 10(-2) M K+ bath solution. RESULTS: All three drug groups produced apparent biphasic effects with a cumulative increase of Ca2+ concentration compared with control groups. An initial increase at low Ca2+ concentration was followed by a decrease of Ca(2+)-activated contractions. Isoflurane affected Ca(2+)-induced contraction significantly more than halothane and sevoflurane. CONCLUSIONS: The results imply that volatile anaesthetics influence Ca(2+)-dependent activity of coronary smooth muscle by complex mechanisms, which involve promotion of intracellular Ca2+ release and other mechanisms that alter sensitivity to calcium.

Anesthetics, Inhalation↗

[Education of the medical student in first aid, emergency and disaster medicine--the Graz model].

In Austria emergency and disaster medicine is a young interdisciplinary subject. It is only a borderline discipline encompassing different medical subjects and was subdivided into emergency medicine for medical doctors only and first-aid for lay people and emergency technicians. In fact, since emergency medicine without first-aid can't be successful, the Department of Anaesthesiology at the University of Graz let all students of the medical faculty have a comprehensive education in the treatment of injured of acutely ill patients. According to the three steps of the study lectures and practices, all parts of first-aid, emergency and disaster medicine were offered. In spite of the short time since this has been running, we found a good acceptance and we hope to increase the interest evinced by medical students in our training programme.

Austria↗

[The effect of 6% HES 200/0.6-0.66 on plasma volume and blood coagulation].

The main goal of the recent study was to evaluate changes in plasma volume due to the application of 6% HES 200/0.6-0.66. 12 patients according to the ASA physical status classification (I, II) undergoing minor surgical interventions received 500 ml of this artificial plasma substitute within 30 min. In a control group (n = 12), 500 ml of lactated Ringer's solution was given within the same period. A further question of the present investigation was the possible influence of 6% HES on coagulation during the following period (1st-3rd postoperative days). 6% HES 200/0.6-0.66 led to an additional augmentation of plasma volume measured via the mechanical oscillator technique of 200 ml (40% of the volume given) immediately at the end of infusion. A second increase in plasma volume of 100 ml (20% of the volume infused) could be observed 1 h later. With exception of the activity of factor VIII, the coagulation parameters had not been altered by infusion of 6% HES. The activity of factor VIII decreased to about 50% of the control level but showed a tendency to normalization within the following observation period. 6% HES 200/0.6-0.66 has a marked volume-expanding effect and exerts no influence on coagulation except a temporary decrease of factor VIII activity.

Adult↗

[Acoustic evoked brainstem potentials--patterns of stimulus artefacts in irreversible coma].

Brainstem auditory evoked potentials (BAEP) were performed in a total of 20 subjects (mean age 33.2 +/- 15.1 years; severe head injury in most cases) with the diagnosis of coma dépassé. The control group consisted of 33 healthy volunteers (mean age 26.9 +/- 5.3 years). The presence, latency and amplitude of the single BAEP-components and the variations of the stimulus artifact were evaluated. The mean amplitudes of the stimulus artifact of the brain dead subjects were calculated (means +/- SD) to be 0.26 +/- 0.12 microV (control group: 0.11 +/- 0.03 microV). Pathological alterations of the mechanics of the inner ear as well as extracerebral changes in conductivity or stimulus related depolarization processes in extracerebral parts of the auditory system were taken into consideration to be possible reasons for this significant (p less than 0.001; t-test) difference.

Adolescent↗

[Is sufentanil suitable for long-term sedation of a critically ill patient?].

Sedation and analgesia are commonly practised in critically ill patients. The drugs and techniques used vary widely, however. Many reports have emphasized that analgesia has to be the primary goal in every therapeutic intervention in critically ill patients. The new narcotic sufentanil has been in use since 1987 in our intensive care unit. PATIENTS AND METHODS. Forty-nine patients in our ICU received sufentanil during controlled mechanical ventilation. The dose given was 0.75-1.0 micrograms.kg bw-1.h-1. In a second part of this study sufentanil was also administered to patients during the weaning period. The dose administered was 0.25-0.35 micrograms.kg bw-1.h-1. RESULTS. With sufentanil analgesia and sedation, most of our patients could be managed well; for only five patients the amount of sufentanil given was too small (Fig. 1). Sufentanil did not show any negative influence on haemodynamic variables, such as heart rate and mean arterial pressure; in addition, serum cortisol levels were not decreased (all values within normal range; Fig. 2); during the weaning phase sufentanil 0.25-0.35 micrograms/kg also proved to be excellent; paCO2 levels did not show any tendency to increase to abnormal levels (Fig. 3). CONCLUSIONS. Analgesia and sedation with sufentanil proved to be satisfactory in critically ill patients. In a dose range of 0.75-1.0 micrograms.kg bw-1.h-1 this drug can safely be given to patients undergoing controlled mechanical ventilation. Caution is necessary in hypovolaemic patients, in whom hypotension can occur if sufentanil is administered in the recommended dose. Sufentanil in a dose range between 0.25-0.35 micrograms.kg bw-1.h-1 is safe when given to patients during the weaning period.

Adolescent↗

The importance of early detection and therapy of reexpansion pulmonary edema.

Three cases are reported of unilateral pulmonary edema, two following rapid reexpansion after prolonged tension pneumothorax, with total collapse of the right lung and one after reexpanded atelectasis following left intrabronchial obstruction. In all cases decrease of blood pressure and tachycardia not responding to intravenous fluid substitution were already present within the first 15 min after chest drainage or after removal of the intrabronchial obstruction. The preexistent dyspnea failed to improve. A cloudy opacity of the reexpanded lung was found immediately after drainage in 2 cases. After immediate application of a continuous positive airway pressure mask no more extensive therapy was necessary in one patient. The two others in whom treatment was begun with more than 1 hour delay required artificial ventilation and adrenergics for 2 and 4 days, respectively.

Adult↗

Postoperative myocardial ischaemia in patients with recent myocardial infarction.

Fifteen patients (10 men and five women; mean age 67.3 yr) with a history of a recent (less than 1 yr) myocardial infarction underwent ambulatory ECG monitoring for 5 days after non-cardiac surgery. The duration, number and severity of ischaemic episodes were maximal within the first 12 h after surgery and again on the 3rd day after operation. The difference in the duration of ischaemic episodes between the 2nd and 3rd days after operation was statistically significant (P less than 0.05). There were no perioperative myocardial infarctions and all patients were discharged from hospital.

Aged↗

[Emergency systems in Styria].

Since 1980 the emergency systems of Graz consisting of two emergency ambulances, two large space emergency ambulances and an emergency helicopter with a range of more than 50 km has been sufficient. The two helicopters cover nearly 100% of the Federal State of Styria but regarding the ground emergency systems there are still insufficiently covered areas in many parts of our state. The ground emergency systems can only be supported but they cannot be replaced by the helicopter. We hope to have an emergency ambulance at every peripheral hospital in the future. Now an efficient emergency system exists in Graz since the first public lecture on first aid and reanimation has been held 175 years ago. The missing link of a well functioning rescue chain is a well trained lay assistant whose level of training regarding "Life Saving Emergency Measures" constantly has to be refreshed. Only with a sufficient number of trained lay assistants it is possible to save all those who have a real chance of successful reanimation.

Aircraft↗

[The importance of pulse oximetry for anesthesia].

With the combination of a noninvasive saturation measurement and plethysmography, pulse oximetry has become an important monitoring method for peripheral perfusion and oxygen supply. Indications for pulse oximetry is practically every anaesthesia especially in geriatric patients and patients with one-lung-anaesthesia, obesity, asthma and emphysema. Pulse oximetry has proved its worth in the transport of emergency patients. Sources of error are a bad perfusion at the site of measurement (hypotension, hypothermia), dyshaemoglobinaemia (Met-carboxy-haemoglobin) and interference of colours (dark skin, intravenous colours, high light intensity). Accuracy of response of most currently available pulse oximeters lies between 2-3% (SD) with oxygen saturations between 80-100%. Deviations increase at lower oxygen saturations. Pulse oximetry will soon be regarded as minimal monitoring standard worldwide together with the ECG, blood pressure, pulse and respiratory monitoring.

Anesthesia↗