Reaction calculations for 17O+12C including fusion within the molecular particle-core model.
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Journal Article↗
Biomedical subjects
A Thiel
Publications and source records attributed to A Thiel.
[Preparation for colonoscopy using Golytely--a sure method? Comparative histological and clinical study between lavage and saline laxatives].
UNLABELLED: Looking at clinical side-effects, effectiveness and tolerability, we compared the salinic solution "Golytely" vs. a conventional preparatory procedure (Cascara-Salax) in a prospective study including 28 patients with macroscopic normal mucosa. Mucosal changes in colonic step biopsies were investigated according to prefixed criteria. RESULTS: There was no significant difference concerning weight, blood pressure, pulse rate, body temperature or essential laboratory findings. Whereas preparation using Cascara-Salax was less molesting stated by the patients, there was no difference in the way colonoscopy itself was tolerated in both groups. The performing doctor's evaluation of the colonic cleaning effect and examination conditions showed "Golytely" significantly ahead of Cascara-Salax. Histologically, colonic mucous layers depicted changes in the control groups in 63% vs. 40% in the "Golytely" group. "Golytely" seems to provide a safe and effective method of preparation for colonoscopy.
Colon↗
Transcranial Doppler sonography and somatosensory evoked potential monitoring in carotid surgery.
Ninety-seven patients undergoing 103 carotid operations were studied intraoperatively using somatosensory evoked potentials after median nerve stimulation (SEP) and transcranial Doppler sonography (TCD). SEP were recorded from the scalp (C3'-Fz or C4'-Fz) and from the second cervical vertebra. The amplitude of the primary cortical response (N20P25) was measured peak-to-peak. Central conduction time (CCT) resulted from the difference between the first negative cortical (N20) and cervical (N14) response. TCD was performed using a pulsed 2-MHz-Doppler device to record the mean blood flow velocity of the middle cerebral artery (Vm-MCA) transtemporally. TCD and SEP variables were registered prior to and after carotid clamping, at short intervals during the clamping period, and after declamping. Critical SEP alterations (N20P25 less than 50% and/or CCT greater than 20% compared to the preceding values) were regarded as significant indicators of cerebral ischaemia, and selective intraluminal shunting was generally based on SEP criteria. The incidence of critical SEP changes was compared to Vm-MCA reductions greater than 60% using the Chi2-test. With SEP always recordable, additional TCD monitoring was possible in only 78 patients in our series for technical or anatomical reasons. Vm-MCA reductions greater than 60% were associated with critical SEP alterations in six cases. In five patients, Vm-MCA was reduced greater than 60% without relevant SEP changes, whereas one patient with critical SEP findings had only a minor Vm-MCA reduction (33%). In the remaining 66 cases, carotid clamping was tolerated without critical SEP changes associated with Vm-MCA reductions not exceeding 60%.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Flow Velocity↗
[Achilles tendon rupture. Anamnestic and morphologic studies and considerations on the etiology].
From 1. October 1985 to 31. December 1987 93 patients (82 male, 11 female) with rupture of the achillestendon were investigated by means of a questionnaire, the specimens obtained at operation were examined histologically. In two cases the operation was for a rerupture of the tendon, 7 and 8 weeks respectively after the first operation. In 6 cases a rupture followed a so-called incomplete rupture on the same side. 9 patients had had a tendonrupture of the other side between 2.5 and 10 years previously. 85.4% of the ruptures took place during a sporting activity. Of the 93 patients 55 (59%) regularly took part in long term sporting activities. Symptoms in the area of one or both achilles tendons were experienced by 32% of the patients. 80 patients with an achilles tendon rupture who were operated within 10 days demonstrated structural degeneration of at least moderate proportions, mostly severe or very severe (there was no relationship between the degree of degeneration and the age of the rupture). The signs of repair were consistent with the age of the rupture. In 56% of the ruptures up to four days old the repair process was considerably more advanced than the age of the rupture would suggest. 6 of 10 patients with the so-called "Archillodynie" demonstrated minor changes although 3 had more severe degenerative changes. Our inquiry clearly demonstrates that structural changes in the tendon took place before the injury. In the cases of achilles tendon rupture the processes of repair are an-adequate to compensate for the degenerative changes. The etiology of the structural degenerations is dependent on many endogenous and exogenous factors particularly the inadequacy of the repair processes.
Achilles Tendon↗
[Isoelectric focusing--a possibility for the demonstration of gingival sulcus fluid].
According to the necessity for examinations of humoral immune response in the oral cavity a new method for evaluating the gingival sulcular fluid proteins is described. In combination of isoelectric focussing on ultrathin-layer polyacrylamide gels, with silver staining a possibility for representing a small quantity of protein as to be expected in sulcular fluid, was found.
Adult↗
[Hyperosmolar volume replacement in heart surgery].
The ideal solution for use in volume therapy is still a matter of debate. Hypertonic sodium (HS) solutions have been advocated for resuscitation from hemorrhagic shock (small volume resuscitation). As hypertonic fluids may also be of interest in cardiac surgery, the effects of a new HS solution were studied. METHODS. In 90 patients undergoing aorto-coronary bypass grafting studies were performed at three different periods: I (n = 30) after induction of anesthesia (before onset of the operation); II (n = 30) during cardiopulmonary bypass (CPB); III (n = 30) after termination of bypass. During these periods the patients were randomly allocated to one of three groups with 10 patients in each group: group 1 received a new hypertonic solution prepared in hydroxyethyl starch (HES) solution (72 g/l NaCl, 60 g/l HES, 2400 mosmol/l; HS-HES patients), group 2 received a 6% HES solution (200/0.5; HES patients), and group 3 received no volume infusion and served as controls. RESULTS. After the induction of anesthesia, significantly less HS-HES solution (4.5 +/- 0.5 ml/kg) than 6% HES solution (10.1 +/- 1.4 ml/kg) was necessary to double the baseline PCWP. The fluid balance during CPB was negative in the patients who had received HS-HES preoperatively (-0.03 +/- 0.01 ml/kg.min CPB), whereas 6% HES (+0.06 +/- 0.02 ml/kg.min CPB) and control patients (+0.13 +/- 0.03 ml/kg.min CPB) had a positive fluid balance. Both after the induction of anesthesia and after termination of bypass, CI increased more in the HS-HES group than in the HES patients, and it even decreased in the control group. SVR decreased in the HS-HES patients, whereas it increased in the control group. Rapid infusion of HS-HES during CPB was followed by a significant, but short-lasting decrease in MAP (-40 mmHg) and an increase in the oxygenator volume. Pulmonary gas exchange (= paO2) was least compromised in the HS-HES patients; the sodium concentration increased only in the HS-HES patients, but never exceeded 150 mmol/l. DISCUSSION. Cardiac surgery procedures offer a special situation for volume therapy as there is a possibility of deterioration in the macro- and microcirculation before, after, and during the period of CPB. Hemodynamic effects of the new HS-HES solution included an increase in CI and a decrease in SVR, which were not merely transient as has been reported which hypertonic saline solution used alone. It was also observed that HS-HES patients required significantly smaller volumes of fluids, both during CPB and during the early postoperative period. This effect seems to be due to a redistribution of interstitial fluid to the intravascular space, possibly decreasing tissue edema. CONCLUSION. The hypertonic saline HES solution adds a new dimension to volume therapy for cardiac surgery patients. The improvement in hemodynamics was effective and not only transient. Fluid requirements were significantly reduced during as well as after CPB, and pulmonary gas exchange was least compromised in these patients.
Aged↗
[Detection of cerebral microembolisms during extracorporeal circulation with pulsatile flow using transcranial Doppler monitoring].
The incidence of focal neurological deficits and diffuse neuropsychiatric disorders in patients undergoing open-heart surgery still remains unacceptably high. The consensus is increasing that diffuse microembolism is the most important cause. Changes in blood flow velocity in the middle cerebral artery were investigated by transcranial Doppler sonography in 26 patients regarding the effect of continuous and pulsatile perfusion during extracorporeal circulation. The quotient of systolic and diastolic flow velocity was significantly increased in patients with pulsatile perfusion. Abnormal high-frequent Doppler-signals were registered in 8 patients using pulsatile perfusion without diastolic basic flow. All the other patients in whom continuous pump flow was applied (13) did not reveal any signs of hemodynamic disturbances. In the group treated with pulsatile perfusion the systolic pressures before and behind the oxygenator were significantly increased in patients with high-frequent Doppler-signals which are likely to be caused by gaseous microemboli. Investigating one type of four different oxygenators no cerebral hemodynamic alterations were recorded even during pulsatile perfusion. The use of membrane oxygenators and arterial filters during pulsatile perfusion cannot completely prevent the occurrence of gaseous microemboli; their principle causes are supposed to be the level of perfusion pressure, the flow velocity and the design of oxygenator.
Blood Flow Velocity↗
[Transcranial Doppler sonography during pulsatile and non-pulsatile extracorporeal circulation].
Transcranial Doppler sonography (TCD) was used to determine the mean blood flow velocity of the middle cerebral artery (Vm-MCA) and pulsatility (systolic/diastolic flow velocity = S/D) in 25 patients undergoing aortocoronary bypass grafting before, during, and after extracorporeal circulation (ECC). Preoperatively, none of the patients had signs or symptoms of cerebrovascular disease. ECC was performed with 2.4 l/min per m2 under mild hypothermia (34 degrees C) using membrane oxygenators. After 20 min of nonpulsatile perfusion, ECC was switched to the pulsatile mode for 20 min. Nonpulsatile perfusion was applied for the remaining ECC period. Vm-MCA, S/D, mean arterial blood pressure (MABP), and nasopharyngeal temperature (T.np) were recorded continuously throughout the operation. Hematocrit and paCO2 were determined before, during, and after ECC. Following hemodilution after the introduction of ECC, Vm-MCA was significantly increased compared with the baseline values before ECC. With hematocrit and paCO2 varying insignificantly during ECC, the onset of pulsatile ECC decreased Vm-MCA and MABP simultaneously. After the re-establishment of nonpulsatile ECC, both Vm-MCA and MABP increased again. However, a linear relationship between the two variables could not be documented statistically. During pulsatile ECC, pulsatility (S/D) of the obtained TCD wave forms did not reach baseline values. In 4 cases, TCD showed cessation of diastolic blood flow velocity after induction of ECC or onset of pulsatile ECC. An increase in MABP or changes in ECC regimen promptly restored diastolic TCD signals in these cases. Our results support the concept of increased cerebral blood flow under mild hypothermic ECC. Compared with the nonpulsatile perfusion mode, we found Vm-MCA reduced during pulsatile ECC.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Early detection of cerebral ischemia during carotid endarterectomy using transcranial Doppler sonography and somatosensory evoked potentials.
Cerebral function during carotid endarterectomy can reliably be monitored using somatosensory evoked potentials (SEP). Transcranial Doppler sonography (TCD) is a noninvasive method providing on-line data about cerebral hemodynamics. The combination of both techniques during carotid surgery is helpful in evaluating the hemodynamic ("input") and the functional ("output") consequences of carotid clamping within a short time. In the present report, combined TCD and SEP monitoring early detected left hemispheric ischemia in a 68-year-old woman subjected to left carotid endarterectomy. The impairment of cerebral perfusion occurred before carotid clamping due to an intraoperative thrombosis of the left internal carotid artery as could be revealed after declamping. A temporary shunt was not inserted. Postoperatively, the patient had a new transient neurological deficit. In this case, TCD correctly indicated cerebral ischemia as confirmed by SEP recording. For carotid artery surgery, combined TCD and SEP may be helpful in detecting those patients who will profit from temporary shunting if this is not done routinely.
Aged↗
Revascularization of the right coronary artery: influence on thermodilution right ventricular ejection fraction.
This study was designed in order to evaluate the influence of right coronary artery (RCA) disease and its revascularization on right heart performance monitored by measuring thermodilution right ventricular ejection fraction (RVEF). Forty patients undergoing elective aortocoronary bypass surgery were divided into two groups: group 1, with RCA revascularization, n=20; and group 2, without RCA disease or revascularization, n=20. RVEF was measured using a pulmonary arterial catheter mounted with a fast-response thermistor and a bedside microprocessor ejection fraction computer. The major finding of the study was that myocardial revascularization with extracorporeal circulation was followed by a decrease in RVEF which was significantly more pronounced in group 1 (-13.1%) in comparison to group 2 (-5.0%). RVEF gradually increased after bypass, but did not reach baseline values. By the first postoperative day, RVEF had reached baseline values again in group 1 and had increased beyond baseline values in group 2. Traditionally measured hemodynamic parameters could not be correlated with the course of RVEF, except for cardiac index. The present study further suggests that right-sided events may have clinical effects on left-sided function. Inadequate protection of the right heart, especially in patients with RCA stenosis, may result in depression of right ventricular myocardial performance, which can be monitored serially by measuring RVEF.
Blood Pressure↗
[Non-invasive versus invasive cardiovascular monitoring. Determination of stroke volume and pulmonary hydration using a new bioimpedance monitor].
Measurement of hemodynamic parameters by noninvasive techniques is gaining more and more popularity in the face of severe complications associated with invasive methods. Thoracic electrical bioimpedance is a noninvasive means of estimating cardiac output (CO) and pulmonary edema formation. The validity of this method, however, has been controversial. In the present study a new bioimpedance monitoring system (NCCOM 3) was used in 10 intensive care patients undergoing mechanical hemofiltration (group I) and in 20 cardiac surgery patients undergoing either aortic valve replacement (AVR, group IIa, n = 10) or aorto-coronary bypass grafting (CABG, group IIb, n = 10). In cardiac surgery patients the measurements were performed before as well as after extracorporeal circulation (ECC). CO measured by the impedance monitor was compared to the standard thermodilution method; pulmonary fluids were estimated by a thermo-dye technique and by measurement of total electrical impedance (base impedance), expressed as the thoracic fluid index (TFI). The principal finding of the study was that CO as measured by the two techniques differed significantly in all groups with regard to absolute values. The relative changes in CO, however, were comparable in both intensive care patients and CABG patients. In patients with special thoracic blood flow conditions (regurgitation in aortic insufficiency patients), no corresponding course of CO could be found.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Kidney Injury↗
[Transcranial Doppler sonography as an intraoperative monitoring procedure. Initial experiences in aortocoronary bypass operations].
Changes in blood velocity in the middle cerebral artery (MFV) were investigated by transcranial Doppler sonography (TCD) in 24 patients undergoing aortocoronary bypass grafting before, during, and after extracorporeal circulation (ECC). Simultaneously, mean arterial blood pressure (MABP), PaCO2, PaO2, and hematocrit were recorded. During ECC, an increase in MFV could be observed that was most pronounced during the early bypass stages. After ECC, MFV decreased slightly but was significantly higher than before ECC. No linear relationship between MFV and MABP could be registered except for the early bypass stage. Neither duration of ECC nor aortic clamping time showed any correlation with MFV augmentation. Mean PaCO2 was held constant (36 mmHg) with PaO2 being at least 120 mmHg. After removal of the aortic clamp, high-frequency Doppler signals probably caused by air or fragment embolization were detected in some patients. Our data support previous observations of increased cerebral blood flow during nonpulsatile ECC. During short episodes of low-pressure perfusion after initiation of ECC, cerebral autoregulation seemed impaired. However, our results do not support the concept of complete loss of autoregulation during ECC. Compared to the xenon technique of measuring cerebral blood flow, TCD allows noninvasive and continuous evaluation of cerebral hemodynamics, thus offering new possibilities of monitoring cerebral blood supply intraoperatively.
Adult↗
[Neurophysiologic monitoring: EEG and evoked potentials].
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Anesthesia, General↗
[Evoked potentials and inhalation anesthetics].
Intraoperative monitoring of evoked potentials can be affected by various factors including volatile anaesthetics. These effects have to be considered in order to give correct interpretations of the obtained data. Visual evoked potentials (VEP) and auditory evoked potentials (AEP) will show strong alterations under general anaesthesia whereas brainstem auditory evoked potentials (BAEP) are slightly affected. The effects of nitrous oxide, halothane, enflurane, and isoflurane on somatosensory evoked potentials (SEP) after median nerve stimulation were studied in 35 healthy adult patients. pCO2 and tympanic membrane temperature were held constant. Simultaneous cervical and cortical SEP recording was performed using surface electrodes. After induction of anaesthesia SEP were recorded during normoventilation with 100% oxygen and after inhalation of 66.6% nitrous oxide. 10 patients received halothane at inspired concentrations of 0.5, 1.0, 1.5, and 2.0%. After nitrous oxide had been replaced by oxygen, halothane was reduced in steps of 0.5%. SEP were recorded at the end of each period (15 min). Equipotent doses of enflurane or isoflurane were administered to 15 and 10 patients, respectively. Nitrous oxide depressed early cortical SEP amplitude. Halothane, enflurane, and isoflurane caused dose dependent increases of latencies. Reduction of amplitude was most pronounced with isoflurane. Using high doses of enflurane in oxygen cortical SEP showed unusual high amplitudes associated with marked increases of latencies. Even under high concentrations of volatile anaesthetics cervical SEP were minimally affected. The effects of anaesthetic gases have to be considered when SEP are recorded intraoperatively.
Anesthesia, Inhalation↗
[Somatosensory evoked potentials in obliterating interventions of the carotid bifurcation].
A prospective study was undertaken to determine the prognostic value of somatosensory evoked potentials during carotid artery surgery in patients where an intraluminal shunt was not used. During a three-year period 167 patients underwent 193 consecutive carotid endarterectomies under general anaesthesia. The somatosensory evoked potential after median nerve stimulation including calculation of central conduction time was used to assess cerebral function intraoperatively. Early postoperative neurologic morbidity was 3.6%, mortality 0.6%. Evoked potential changes in these patients were uniform and consisted of an increase in central conduction time of more than 20% from control (anaesthetic baseline), a decrease of the amplitude of the primary cortical response exceeding 50% and a loss of middle latency components. In subsequent recordings complete loss of the entire cortical evoked potential was observed in 5 of 7 patients. Sensitivity of CCT prolongation was 100%, specificity 89% (18 false positives). For amplitude reduction sensitivity was 86% (1 false negative), specificity 96% (7 false positives). For loss of the entire cortical response sensitivity was 71% (2 false negatives), specificity 99% (2 false positives). The above mentioned parameters correlated with postoperative neurologic state (Chi-square, p = 0.0001). Since the effects of potentially confounding variables (anaesthetics, temperature) are well known, the somatosensory evoked response, especially central conduction time, can be used as a reliable guide for brain supporting procedures.
Brain Ischemia↗
Inelastic excitation and neutron transfer in the 13C-13C scattering with the molecular particle-core model.
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Journal Article↗
[Effect of isoflurane and enflurane on somatosensory evoked potentials following stimulation of the median nerve].
The effects of enflurane and isoflurane on somatosensory evoked potentials (SEP) after median nerve stimulation were studied in 25 healthy adult patients. Cervical and cortical SEP were recorded simultaneously. pCO2 and tympanic membrane temperature were kept constant. Following induction of anaesthesia with thiopentone, fentanyl and succinylcholine SEP were recorded during normoventilation with 100% oxygen and after inhalation of 66.6% nitrous oxide. Isoflurane at inspired concentrations of 0.8, 1.65, 2.5, 3.3% was given to 10 patients at 15 minutes intervals and was reduced after nitrous oxide had been replaced by oxygen. 15 patients received equipotent doses of enflurane (1.1, 2.2, 3.25, 4.3%.) SEP were recorded at the end of each interval. Isoflurane and enflurane caused dose dependent increases in latency of the cortical SEP. This effect was more pronounced with enflurane. Isoflurane reduced amplitude of the primary cortical response more than enflurane, when ventilation was performed with 66.6% nitrous oxide in oxygen. High doses of enflurane in oxygen augmented cortical SEP amplitudes associated with a marked increase in latency. Isoflurance and enflurance anaesthesia slightly altered cervical SEP. Middle latency components of the cortical SEP were progressively diminished with increasing isoflurane or enflurane concentrations. The effect of both agents in terms of delayed latencies and reduced amplitudes should be considered when recordings are performed intraoperatively.
Adolescent↗
[Somatosensory evoked potentials under thiopental and etomidate].
The somatosensory evoked potential in response to median nerve stimulation was recorded in 42 patients during infusion of either 15 mg/kgbw thiopentone (TH) or 1 mg/kgbw etomidate (E) within 15 min and before and after injection of 0.3 mg/kgbw etomidate bolus. Cortical and cervical responses were analysed simultaneously and central conduction time (CCT) was calculated. Marked alterations of waveforms and an increase in latency of the primary cortical SEP and of CCT were observed in all patients. Infusion of TH or E was followed by a diminution of middle and long latency components. Amplitude of the cortical N20 was found to be unchanged during and after TH and to be increased after infusion or injection of E, indicating the synchronizing properties of this drug. The cervical SEP (N14) remained entirely unchanged in response to both agents. During hypnotic drug administration a pronounced increase in latencies and CCT as well as a decrease in the number of identifiable peaks has to be considered when SEP monitoring is performed intraoperatively or in intensive care treatment.
Anesthesia↗