[Resuscitation measures in life-threatening incidents in dental practice. Anesthesiological viewpoint].
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Anesthesia, Dental↗
Biomedical subjects
M Zimpfer
Publications and source records attributed to M Zimpfer.
Blood brain barrier modification and chemotherapy. Interventional neuroradiology in the treatment of malignant gliomas.
Postoperative interventional neuroradiology was performed in patients with malignant gliomas to increase target efficacy of chemotherapy. In 8 glioma patients the blood brain or blood tumor barrier was reversibly opened by intraarterial injection of hyperosmolar fluid (Mannitol 25%). One additional patient had primary lymphoma of the central nervous system. During barrier modification chemotherapeutic agents were applied intraarterially and intravenously. A total of 22 blood brain barrier modification procedures have been carried out until now, ranging from one to five per patient. A presently continuing tumor regression or tumor progression free intervals have been noted in 5 patients. Therapeutic effects are being evaluated from repeated computed tomography and single photon emission computed tomography examinations.
Adult↗
[Method of determining glomerular filtration rate and extracellular fluid volume in the perioperative phase].
In the course of an investigation concerning the renal response in abdominal surgery, we paid special attention to the precision of determination of the glomerular filtration rate (GFR) and extracellular fluid volume (ECF). The influence of the applied mathematical model on calculation using slope techniques was examined. ECF and GFR were measured by single injection of the radioactive tracer 51Cr-EDTA; plasma samples were taken during the first 4 h postinjection. The results were computed according to the compartmental and noncompartmental model. The correlation between two-compartmental and noncompartmental GFR and ECF values was highly significant. However, values calculated from two-compartmental model were significant lower (p less than 0.01) and differences up to 20% were observed. Calculating ECF by the most widely used approximative method (assuming an early equilibrium between the extra- and intravascular part of ECF) yields incredible high values and correlation to other methods was poor. Based on our data, we conclude that GFR and ECF values obtained by compartmental analysis depend on flow rates between the theoretical compartments. Also the use of two or three exponential components for the plasma curve in the course of noncompartmental analysis (as done by most authors) is not any better than compared conventional compartmental analysis. Noncompartmental analysis should be preferred especially when small changes in ECF and GFR are observed, as it is the more accurate.
Body Fluid Compartments↗
[Behavior of renal filtration performance in the massive intraoperative administration of crystalloid solutions].
Renal function of 12 adult patients was studied pre- and postoperatively using tracer techniques in a black-box model. Chrom 51 EDTA was employed to determine extracellular fluid volume and glomerular filtration rate, Iodine 125-albumin to measure plasma volume. These patients who received during two 4-h periods pre- and postoperatively 3 ml/kg/h of a salt-sugar solution had a significantly increased extracellular fluid volume postoperatively. Glomerular filtration rate was also increased, plasma volume was significantly reduced and colloidosmotic pressure in spite of attempts to supplement albumin solution intraoperatively was found to be postoperatively reduced. Hemodynamic parameters were virtually unchanged postoperatively with the exception of a small but significant increase of cardiac index. It is concluded, that these patients who received 12 ml/kg/h of crystalloid solutions apart from colloid replacement of measured bloodloss intraoperatively through natural regulation were about to excrete this extra amount of fluid, which had been relocated in the extracellular space. This regime, however, might help to decrease the rate of oliguric perioperative renal function failure, which has a high mortality.
Adult↗
[Effect of enflurane on the function of the chronically ischemic myocardium].
The effects of enflurane on the function of the chronically ischemic myocardium were studied in nine dogs, 2-8 weeks after implantation of Doppler-ultrasound flow transducers around the circumflex branch of the left coronary artery, of pairs of ultrasonic crystals in normal and ischemic regions of the left ventricle, aortic catheters, and of solid-state left ventricular pressure gauges. Enflurane (2% and 4% inspired) caused an increase in heart rate and dose-dependent decreases in left ventricular pressure, dP/dt, mean arterial pressure and mean circumflex coronary resistance. However, in comparison to the normal myocardium neither exaggerated nor permanent dysfunction of the chronically ischemic but still contracting myocardium was noted. Thus, reduction of coronary perfusion pressure and coronary vasodilatation does not seem to be of major functional significance in determining ischemic left ventricular performance during anesthesia with enflurane.
Animals↗
Importance of myocardial loading conditions in determining the effects of enflurane on left ventricular function in the intact and isolated canine heart.
The effect of enflurane (2% and 4% inspired) on left ventricular (LV) function were examined in chronically instrumented dogs, both intact and after isolation of their hearts and lungs from the systemic circulation. Enflurane in the intact dogs increased heart rate (32 +/- 5% with 2% and 41 +/- 4% with 4%) and elicited striking, dose-dependent decreases in LV stroke shortening (-30 +/- 3% and -41 +/- 4%), the maximum velocity of LV fiber shortening, dD/dt, (-23 +/- 2%) and -40 +/- 2%), LV systolic pressure (-25 +/- 3% and -33 +/- 2%), the maximum rise of LV-pressure, dP/dt (-33 +/- 5% and -55 +/- 3%), and mean aortic pressure (-27 +/- 2% and -37 +/- 1%). However, the LV diastolic performance was impaired little, i.e., even with the higher concentration the LV end-diastolic pressure rose only moderately (32 +/- 4%), while the LV end-diastolic dimensions failed to change significantly; both LV end-diastolic pressure and LV end-diastolic diameter were decreased with the low concentration. Enflurane, after beta-adrenergic blockade alone or after combined beta-adrenergic and cholinergic blockades, or with spontaneous ventilation instead of controlled ventilation, had similar effects. By contrast, in the hearts that were isolated from the systemic circulation and the complex neurohumoral environment, enflurane increased both LV end-diastolic pressure (116 +/- 32% and 492 +/- 58%) and LV end-diastolic diameter (13 +/- 3% and 28 +/- 7%). In intact dogs with aortic pressure artificially increased to conscious control levels, enflurane likewise caused a distinct depression of the LV diastolic performance. Thus, LV systolic unloading appears to be mandatory in order to prevent acute myocardial failure from higher doses of enflurane. The observed changes in LV function with enflurane are largely independent of cardiac rate, adrenergic and cholinergic influences, and the hemodynamic consequences of intermittent positive-pressure ventilation.
Animals↗
[Effects of morphine on the control of the cardiovascular system by the carotid-sinus-reflex and by the carotid chemoreflex].
The effects of morphine (2 mg/kg i.v.) on the carotid baroreceptor control and the carotid chemoreceptor control of the circulation were examined in 12 chronically instrumented dogs. Bilateral carotid occlusion in conscious dogs with spontaneous ventilation increased heart rate (decrease in cardiac cycle length by 19 +/- 2%; mean +/- S.E.M.), mean arterial pressure (38 +/- 3%) and mean iliac resistance (33 +/- 11%). Morphine, however, failed to change these reactions significantly. Chemoreceptor stimulation, accomplished by intracarotid injections of nicotine (4-8 micrograms), in conscious dogs with spontaneous ventilation elicited complex effects on heart rate and mean iliac resistance--due to secondary stimulation of pulmonary inflation reflexes. Chemoreceptor stimulation in conscious dogs with ventilation controlled increased cardiac cycle length (246 +/- 17%) and elicited intense iliac vasoconstriction, i.e. mean iliac resistance rose by 288 +/- 25%. Morphine significantly (p less than 0.01) attenuated the increase in cardiac cycle length and in iliac resistance with chemoreceptor stimulation (42 +/- 10% and 64 +/- 9%, respectively). Thus, morphine interferes with the carotid chemoreceptor control of the circulation while the efficacy of the carotid-sinus-reflex seems to be well maintained.
Animals↗
[Arterial baroreflex in intravenous anesthesia and assisted spontaneous respiration].
Effects of a combined intravenous anaesthesia on the baroreceptor control of the circulation were determined in 8 healthy, unpremedicated patients, 18-50 years of age, scheduled for minor surgical procedures. The baroreflex was studied in response to brief hypotension with nitroglycerin (1-10 micrograms/kg i.v.) and quantified using the method described by Smyth, Sleight and Pickering (1969). The latter linearly correlates measurements of systolic blood pressure and the succeeding pulse interval, as obtained from recordings of the electrocardiogram. Responses in the conscious state were compared with those after administering diazepam (0.2 mg/kg i.v.), etomidate (8-20 mg i.v.) and fentanyl (0.015-0.025 mg/kg i.v.) while the patients were breathing a mixture of oxygen and nitrous oxide (1:2) during mechanically assisted ventilation. Anaesthesia led to a decrease in heart rate (17 +/- 3%) together with a slight but significant reduction in mean arterial pressure (15 +/- 4%). The mean slopes and correlation coefficients in the conscious and anaesthetized states were y = 426 + 2.33 X; r = 0.56; p less than 0.05 and y = 663 + 2.16 X; r = 0.49; p less than 0.05, respectively. Thus, no significant difference of the function of the baroreflex was observed in the conscious and anaesthetized patients. It is concluded that in contrast to inhalational anaesthesia the employed combined intravenous anaesthesia with mechanically assisted ventilation does not change this important control mechanism of the circulation in man.
Adolescent↗
[Effect of morphine on circulatory control in acute progressive hemorrhage].
The effects of acute, progressive haemorrhage, 1 ml/s were examined in the same mongrel dogs on separate days, unanaesthetized and anaesthetized with morphine (2 mg/kg i.v.) and with administration of nasal oxygen to maintain arterial blood gases at physiological levels. In normal, unanaesthetized dogs mean arterial pressure was well maintained through 30 ml/kg of blood loss. Cardiac output fell with haemorrhage (70 +/- 2%; mean +/- S.E.M.) but heart rate and total peripheral resistance rose by 72 +/- 11% and by 124 +/- 11%, respectively. Morphine induced slight but significant changes in heart rate and mean arterial pressure but did not affect the ability to withstand hemorrhage. Thus, in contrast to barbiturates and volatile anaesthetics, morphine does not seem to comprise the efficacy of the rapidly acting pressure control system in response to progressive hemorrhage. The results of the present investigation are not consistent with the hypothesis that opioids are hypotensive factors in hypovolaemic shock.
Acute Disease↗
[Hemoconcentration caused by excessive intraoperative ascites production in ulcer bleeding].
The estimation of the intraoperative fluid requirements can be particularly difficult in patients with compartmental disturbances, e.g. hepatic cirrhosis. The case history of a 41 year old female with a known history of liver cirrhosis is reported who underwent emergency surgery due to upper gastro-intestinal bleeding. In order to maintain hemodynamic stability preoperative blood loss was replaced with fresh blood. During the operation 4 liters of bank and fresh blood with 5 liters of erythrocyte-free fluids were administered. After operation reliable clinical signs of hypovolemia and a marked increase in hematocrit were noted. The severe hemoconcentration was explained by excessive fluid shifts away from the intravascular compartment since a total amount of 10 liters of ascites was collected for the next 24 hours. This overproduction can be related to portal hypertension, hypoalbuminemia and activation of the renin-angiotensin-aldosterone system.
Adult↗
[Cardiac and peripheral vascular effects of the volatile inhalational anaesthetic enflurane in chronically instrumented dogs (author's transl)].
While enflurane is generally held to induce arterial hypotension, its overall effects on left ventricular (LV) performance are less clear. Accordingly, mongrel dogs were chronically instrumented with miniature LV pressure transducers, with aortic and left atrial catheters and with electromagnetic flow probes and hydraulic cuff occluders on a common iliac artery. A pair of ultrasonic transducers was implanted on opposing endocardial surfaces to measure LV internal minor axis diameter. Experiments were performed 2 to 9 weeks after surgery when the animals were resting quietly without premedication. Enflurane (2 and 4 vol.-%) decreased mean arterial pressure by 27% and 36% and led to a progressive, dose-dependent decrease in myocardial contractility and induced striking peripheral vasodilatation, i.e. LV-dP/dtmax was reduced by 32% and 54% and iliac conductance rose by 101% and 163%. However, the decrease in contractility was not associated with an increase in LV preload, i.e. LV-end-diastolic diameter was decreased by 2 vol.-%, while it was not significantly different from control values with 4 vol.-%. Thus, in intact chronically instrumented dogs the direct negative inotropic effect of enflurane is modified by a synchronous decrease in myocardial loading conditions.
Aerosols↗
Inhibition of the carotid chemoreceptor reflex by enflurane in chronically instrumented dogs.
The effect of the volatile inhalational anaesthetic enflurane (2 vol% and 4 vol%) on the cardiovascular response to carotid chemoreceptor stimulation (CCRS) was studied in 8 chronically instrumented dogs. Intracarotid injections of nicotine were used to evoke CCRS. Ventilation was held constant during the unanaesthetized state as well as the anaesthetized state. In the unanaesthetized state CCRS evoked an increase in iliac vascular resistance, and an increase in cardiac cycle length. Enflurane 2 vol% significantly attenuated the increases both in iliac vascular resistance as well as in cardiac cycle length. Enflurane 4 vol% abolished the response to CCRS.
Animals↗
Effect of dobutamine on cardiac function in man: reciprocal roles of heart rate and ventricular stroke volume.
The cardiovascular effects of dobutamine ( 7 micrograms/kg . min iv) and of additional N-allyl-clonidine (St 567, alinidine; 0.3 mg/kg iv), a compound which selectively inhibits the chronotropic effects of various stimulants, were studied in 9 patients scheduled for major abdominal surgery. Dobutamine increased cardiac index (CI), mean arterial pressure (MAP), mean pulmonary artery pressure (MPAP), and heart rate, but failed to change the left ventricular stroke volume (LVSV) significantly. Alinidine decreased cardiac rate and increased LVSV index and left ventricular stroke work index (LVSWI), whereas CI, MAP, and MPAP remained virtually unaffected. Similar results were obtained when the combination of dobutamine and alinidine was given to 4 patients in neuroleptanesthesia. Thus, the decrease in preload which is associated wit tachycardia seems to modify the increase in LVSV in response to inotropic stimulation with dobutamine.
Adult↗
Relative roles of heart rate and ventricular stroke volume for the regulation of cardiac output during controlled hypotension with sodium nitroprusside in man.
The effects of N-allyl clonidine (St 567, alinidine), (0.5 mg/kg i.v.) a substance with specific bradycardic action at the sinus node, were studied on a total of thirteen patients in neuroleptanaesthesia and during controlled hypotension with sodium nitroprusside (SNP). Invariably, the fall in blood pressure was associated with an increase in heart rate (20.0 +/- 4.3+; P less than 0.01), presumably due to an activation of the arterial baroreceptor reflex. Alinidine decreased heart rate to the original level but no fall in cardiac output occurred a ventricular stroke volume and the calculated left ventricular stroke work were increased compensatorily (35.9 +/- 7.2% and 35.9 +/- 6.7%, P less than 0.01, respectively). In patients who received alinidine before the onset of controlled hypotension (n = 5) SNP failed to elicit an increase in heart rate. It is concluded that in patients under neuroleptanaesthesia tachycardiac does not play an important role for the maintenance of an adequate cardiac output during controlled hypotension with SNP.
Adult↗
Pentobarbital alters compensatory neural and humoral mechanisms in response to hemorrhage.
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Animals↗
Phylogenesis of the Bainbridge reflex.
The effects of volume loading were examined on measurements of left ventricular (LV) pressure and heart rate in patients undergoing cardiac catheterization. These data were compared to those collected in conscious dogs and subhuman primates (baboons). In man acute volume loading increased LV end-diastolic pressure by 14 mmHg, but did not increase LV systolic pressure significantly. Similar increases in LV end-diastolic pressure were observed in conscious dogs and baboons. LV systolic pressure also did not rise in baboons, but did increase (+32 mmHg) with volume loading in dogs. In man volume loading increased heart rate by 15 beats/min, significantly less (P less than 0.01) than observed in baboons (+37 beats/min), and which in turn was significantly less than that observed in dogs (+88 beats/min). Thus, the Bainbridge reflex, i.e., the tachycardia that occurs with volume loading, appears to exist in primates including man. However, the extent of utilization of this reflex decreases significantly from nonprimate mammals (dogs) to subhuman primates (baboons) to man.
Adolescent↗
Cardiovascular effects of N-allyl clonidine (ST 567, alinidine): a substance with specific bradycardiac action during neuroleptanesthesia in humans.
The cardiocirculatory effects of N-allyl clonidine (ST 567, alinidine), a substance with specific bradycardiac action at the sinus node [Kobinger et al. 1979], were studied in 30 patients undergoing noncardiac surgery in neuroleptanesthesia. Alinidine (0.5 mg/kg i.v.) alleviated both spontaneous and reactive tachycardia, i.e., in response to deliberate hypotension with sodium nitroprusside (3.0 +/- 1.8 micrograms/kg i.v.), (decrease in heart rate from control: 20.7 +/- 5.7% and 25.4 +/- 3.2%, respectively), without affecting mean arterial blood pressure substantially. The slight but significant reduction in cardiac output can be explained, at least in part, by the decrease in heart rate, since the left ventricular stroke volume showed a tendency to increase and the mean pulmonary artery pressure failed to change significantly. Thus, alinidine may be useful for reducing heart rate and myocardial oxygen consumption in patients under neuroleptanesthesia.
Adult↗
Plasma catecholamines, plasma renin activity and haemodynamics during sodium nitroprusside-induced hypotension and additional beta-blockage with bunitrolol.
The effects of beta-blockade on certain physiological and haemodynamic responses to sodium nitroprusside-induced hypotension have been studied in 5 patients, aged 18--54 years, undergoing inner ear surgery. Samples of blood were collected under premedication, following induction of anaesthesia, during neuroleptanalgesia, during a sodium nitroprusside infusion adjusted to produce a 40% fall in blood pressure, during superimposed beta-blockage with bunitrolol and under stable haemodynamic conditions after discontinuation of sodium nitroprusside. The sodium nitroprusside-induced reduction in blood pressure led to a massive increase in plasma noradrenaline and adrenaline and in plasma renin activity. beta-blockade with bunitrolol did not affect the increased catecholamine concentrations, the increase in plasma renin activity was significantly reduced, the increase in heart rate was reversed, and total peripheral resistance and diastolic blood pressure were further reduced. These changes can be attributed to the intrinsic beta-synmpathomimetic activity of bunitrolol in addition to its beta-blocking effect. Since no adverse effect was observed in this study, combined therapy with sodium nitroprusside and beta-receptor blockade should be employed if the effects of increased sympathetic tone are considered to be undesirable.
Adolescent↗