[Anesthesiology and intensive care medicine in geriatric gynecologic surgery].
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Aged↗
Biomedical subjects
K Peter
Publications and source records attributed to K Peter.
[Acoustic evoked potentials mid-latency following anesthesia with sufentanil].
PATIENTS AND METHODS: We have studied mid-latency auditory evoked potentials (MLAEP) during general anaesthesia with sufentanil in ten patients scheduled for elective major urological surgery. Anaesthesia was induced with sufentanil 2-3 micrograms/kg; for maintenance of anaesthesia a further bolus of sufentanil (1-2 micrograms/kg) 10 min before the start of surgery (skin incision) was given. MLAEP were recorded before and 10 min after the last sufentanil bolus on the vertex (positive) and mastoids on both sides (negative). Latencies of the peaks V, Na, Pa, Nb, and Pl (ms) and amplitudes Na/Pa, Pa/Nb, and Nb/Pl (microV) were measured. RESULTS: In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic wave form. During general anaesthesia with sufentanil the brainstem response V was stable. There was a marked increase in latency and a decrease in the amplitude of Nb and Pl. In contrast, for the early cortical potentials Na and Pa only small increases in latencies and decreases in amplitudes were observed. Na and Pa showed a similar pattern to that in awake patients. CONCLUSIONS: There is no substantial difference of sufentanil's effect on MLAEP compared with the opioids alfentanil, fentanyl, and morphine. Because Na, Pa, and Nb are generated in the primary auditory cortex of the temporal lobe, it must be concluded that during general anaesthesia with sufentanil primary cortical processing of auditory stimuli may be preserved.
Adult↗
[Continuous measurement of cardiac output with pulse contour analysis].
Pulse contour cardiac output (PCCO) is an easily applicable method for continuous measurement of cardiac output in critically ill patients. Calculation of stroke volume is possible by analysing the area under the systolic part of the arterial pulse pressure waveform together with an individual calibration factor (Zao) to account for the individually variable vascular impedance. Since vascular impedance is potentially affected by altered vascular tone, it was the aim of the present study to examine the validity of PCCO in ICU patients receiving various dosages of a variety of vasoactive drugs. PATIENTS AND METHODS. Continuous cardiac output was measured in 20 ICU patients for a total of 110 h using the pulse contour method. The precision of PCCO was determined in comparison with its calibration reference, the thermodilution method (TDCO): (1) during administration of vasoactive drugs at a constant rate and (2) during conditions with altered vascular tone and haemodynamics elicited by changes in vasoactive drug dosage. For this purpose, the patients received varying dosages of vasoactive drugs (dopamine, dobutamine, epinephrine, norepinephrine, nitroglycerin, prostacyclin and urapidil). RESULTS. A total of 165 data sets was obtained, each consisting of the average of four capnometrically triggered TDCO measurements and the corresponding PCCO values. The relative difference between methods (+/- 2 SD) was +/- 23.9% (SD 0.85 l.min-1; r = 0.93) if a single calibration at the beginning of measurement series was performed (Fig. 2). The bias of the mean cardiac output values of both methods was -0.09 l.min-1. The precision of PCCO improved to +/- 15.7% by additional calibrations (SD 0.56.min-1; r = 0.96; bias 0.003 l.min-1). Data of two patients showed that recalibration may be necessary after extreme haemodynamic changes due to septic shock or cooling. Alteration of vascular tone by clinically used dosage of vasoactive drugs, however, had no destabilizing effect on the pulse contour method. CONCLUSIONS. It could be demonstrated that PCCO provides a valuable method for continuous cardiac output measurement in the intensive care setting with a precision comparable to that of thermodilution.
Adult↗
[Awareness during general anesthesia. Definition, incidence, clinical relevance, causes, avoidance and medicolegal aspects].
The possibility that a patient during general anaesthesia is aware of the operation going on and aware of severe pain that might be remembered postoperatively must be very alarming to patients and anaesthetists alike. Furthermore, there is experimental evidence showing that conscious recall of intraoperative events is only the tip of an iceberg; it seems very probable that there is even a higher incidence of unconscious perception during general anaesthesia. Therefore, the following stages of intraoperative awareness must be distinguished: (1) conscious awareness with explicit recall and with severe pain; (2) conscious awareness with explicit recall but no complaints of pains; (3) conscious awareness without explicit recall and possible implicit recall; (4) subconscious awareness without explicit recall and possible implicit recall; (5) no awareness. The incidence of conscious awareness with explicit recall and severe pain has been estimated at less frequent than 1/3000 general anaesthetics. Conscious awareness with explicit recall but no complaints of pain has been reported in the literature with an incidence of 05-2%. With 7-72%, conscious awareness without explicit recall and possible implicit recall shows a very wide range of variation and its occurrence probably depends on the anaesthetic drugs used. Subconscious awareness with possible implicit recall has an incidence of up to 80%, but there are many methodological problems in demonstrating implicit memory of intraoperative events. Reports of intraoperative awareness do not come exclusively from cardiac surgery and obstetrics, but also from all other operative specialties. Postoperatively, patients who experience intraoperative awareness may develop a so-called post-traumatic stress syndrome. Symptoms involve re-experiencing the event awake or in dreams, sleep disturbances, depression, avoidance of stimuli associated with the event. The probability of the development of the post-traumatic stress syndrome seems to coincide with the experience of severe pain. When a patient complains of intraoperative awareness postoperatively the anaesthesiologist should discuss the event frankly with the patient. When the symptoms of the post-traumatic stress syndrome persist a psychotherapy should follow. Causes for intraoperative awareness may be: equipment failure, too-light anaesthesia, e.g. for a caesarean section or for emergency surgery in severely injured or polytraumatized patients, during cardiac surgery, bronchoscopy of difficult intubation. There is interindividual variability in anaesthetic effect; for example, chronic drug or alcohol abuse or overweight may make increased anaesthetic doses necessary. They are at risk for intraoperative awareness. Some general anaesthetics or anaesthetic procedures, e.g. the combination of a relaxant and N2O, opioid mono-anaesthetics, or opioids combined with benzodiazepines, seem to involve a higher risk of intraoperative awareness than do volatile anaesthetics. The bases of litigation are medical malpractice, breach of contract by the anaesthesiologist or lack of informed consent from the patient. Therefore, patients who are at risk of intraoperative awareness should be given detailed information on this special risk before the operation.
Anesthesia, General↗
[Mucosa-pH as a parameter of mucosa oxygenation in liver transplantation].
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Acid-Base Equilibrium↗
Does nitrous oxide affect coronary microcirculation? An intravital microscopic study in the canine heart.
The safe use of nitrous oxide, in particular in patients with coronary artery disease, has been questioned. This study was designed to determine whether nitrous oxide directly affects global coronary hemodynamic variables and coronary arteriolar microvessels in the absence of changes of myocardial oxygen consumption. In dogs the effects of nitrous oxide were evaluated during normotension (NT, intravenous [IV] piritramid, nitrogen/oxygen; and NT/N2O, IV piritramid, nitrous oxide/oxygen) and during hypotension (MAP 60 mm Hg) (HT, IV piritramid, halothane, nitrogen/oxygen; and HT/N2O, IV piritramid, halothane, nitrous oxide/oxygen). The diameter of coronary arteriolar microvessels (range, 20-450 microns) was assessed by intravital fluorescence microscopy. Myocardial blood flow was determined by radioactive microspheres. Systemic and coronary hemodynamics, as well as arteriolar microvessel diameters, were comparable between NT and NT/N2O. During HT, nitrous oxide (HT/N2O) affected neither systemic nor coronary hemodynamics. Moreover, there was no obvious difference in the diameters of coronary microvessels between HT and HT/N2O. In conclusion, nitrous oxide, whether at normotensive or hypotensive conditions, neither influences coronary arteriolar tone nor reduces or redistributes myocardial blood flow.
Animals↗
Anesthesia with increasing doses of sufentanil and midlatency auditory evoked potentials in humans.
Our interest focused on the question whether sufentanil differs from alfentanil, fentanyl, and morphine with regard on its effects on midlatency auditory evoked potentials (MLAEP). Therefore, we studied MLAEP during general anesthesia with increasing doses of sufentanil in 16 patients scheduled for elective major urologic surgery. Anesthesia was induced with sufentanil (1 microgram/kg every 7 min to a total dose of 3 micrograms/kg). In 8 of 16 patients, further incremental doses of sufentanil were given to a total dose of 5 micrograms/kg. Auditory evoked potentials were recorded before and 5 min after every sufentanil dose on vertex (positive) and mastoids on both sides (negative). Latencies of the peaks V, Na, Pa, Nb, and P1 (ms), and amplitudes Na/Pa, Pa/Nb, and Nb/P1 (microV) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anesthesia the brainstem response V was stable to increasing doses of sufentanil. There was a marked statistically significant increase in latency and decrease in amplitude of Nb and P1 after 1-2 micrograms/kg sufentanil, which remained stable under further sufentanil application. In contrast, the early cortical potentials Na and Pa increased only slightly in latencies. This increase was statistically significant at 4 micrograms/kg for Na and at 3 and 4 micrograms/kg for Pa. For the amplitudes Na/Pa and Pa/Nb there was only a slight and statistically insignificant reduction. After the largest dose of sufentanil (3-5 micrograms/kg) Na and Pa showed a similar pattern as in awake patients. We conclude that sufentanil does not differ essentially from alfentanil, fentanyl, and morphine with regard on its effects on MLAEP.
Anesthesia, General↗
Influence of isoflurane, fentanyl, thiopental, and alpha-chloralose on formation of brain edema resulting from a focal cryogenic lesion.
The objective of this study was to analyze the effects of various anesthetics on the formation of brain edema resulting from a focal cryogenic lesion. Thirty rabbits (six per group) were anesthetized with isoflurane (1 minimum alveolar anesthetic concentration [MAC] 2.1 vol%), fentanyl (bolus 5 micrograms/kg; infusion rate 1.0-0.5 micrograms.kg-1.min-1), thiopental (32.5 mg.kg-1.h-1), or alpha-chloralose (50 mg/kg). Control animals (sham operation, no lesion) received alpha-chloralose (50 mg/kg). Regional cerebral blood flow (rCBF) in perifocal brain tissue was measured by H2-clearance. Animals anesthetized with isoflurane required support of arterial pressure by angiotensin II (0.15 micrograms.kg-1.min-1). Six hours after trauma the animals were killed. Formation of brain edema was studied by specific gravity of cortical gray matter, white matter, hippocampus, caudate nucleus, putamen, and thalamus. Brain tissue samples were collected at multiple sites close to and distant from the lesion. Mean arterial pressure, arterial PCO2 and PO2, hematocrit, body temperature, and blood glucose were not different between groups during the posttraumatic course (except for an increased arterial pressure with alpha-chloralose compared to thiopental 4-6 h after trauma). The specific gravity of cortical gray matter was significantly reduced up to a distance of 6 mm from the center of the lesion in animals anesthetized with isoflurane, thiopental, or alpha-chloralose and up to 9 mm in animals given fentanyl.(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthetics↗
Renal function and serum fluoride concentrations in patients with stable renal insufficiency after anesthesia with sevoflurane or enflurane.
Sevoflurane is metabolized to hexa-fluoro-isopropanol and inorganic fluoride by the human liver. Its use as an anesthetic may lead to peak plasma fluoride concentrations exceeding those seen after enflurane. Although there is no nephrotoxicity after sevoflurane anesthesia in humans with normal kidneys, those with chronically impaired renal function might be at increased risk because of increased fluoride load due to prolonged elimination half-life. In this study, measures of renal function after sevoflurane anesthesia were compared to those after enflurane in patients with chronically impaired renal function. Forty-one elective surgical patients with a stable preoperative serum creatinine concentration > or = 1.5 mg/dL were randomly allocated to receive sevoflurane (n = 21) or enflurane (n = 20) at a fresh gas inflow rate of 4 L/min for maintenance of anesthesia. Serum fluoride concentrations were measured by ion-selective electrode. Renal function (creatinine, urea, sodium, osmolality) was assessed in serum and urine preoperatively and for up to 7 days postoperatively. Peak serum inorganic fluoride concentrations were significantly higher after sevoflurane than after enflurane anesthesia (25.0 +/- 2.2 vs 13.3 +/- 1.1 microM; mean +/- SEM). Laboratory measures of renal function Laboratory measures of renal function remained stable throughout the postoperative period in both groups. No patient suffered a permanent deterioration of preexisting renal insufficiency and none required dialysis. Thus, neither sevoflurane nor enflurane deteriorated postoperative renal function in these patients with preexisting renal insufficiency. There is no evidence that fluoride released by metabolism of sevoflurane metabolism worsened renal function in these patients with stable, permanent serum creatinine concentrations more than 1.5 mg/dL.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
The effects of anesthesia with increasing end-expiratory concentrations of sevoflurane on midlatency auditory evoked potentials.
We studied midlatency auditory evoked potentials (MLAEP) during general anesthesia with increasing end-expiratory concentrations of sevoflurane in 12 patients scheduled for elective gynecologic surgery. After oral premedication with 20 mg clorazepate dipotassium, anesthesia was induced with etomidate (0.2 mg/kg intravenously [IV]). Vecuronium (0.1 mg/kg) was given for neuromuscular block, and controlled ventilation with sevoflurane in 100% O2 was instituted. Auditory evoked potentials were recorded in the awake state and during anesthesia with end-expiratory steady-state concentrations of 0.5, 1.0, 1.5, and 2.0 vol% of sevoflurane on vertex (positive) and mastoids on both sides (negative). Latencies of peaks V, Na, Pa, Nb, and P1 (ms) and amplitudes of Na/Pa, Pa/Nb, and Nb/P1 (microV) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anesthesia with increasing end-expiratory concentrations of sevoflurane, the latency of the brainstem response V increased slightly. In contrast, MLAEP showed marked dose-dependent, statistically significant increases in the latencies of Na, Pa, Nb, and P1 and decreases in the amplitudes of Na/Pa, Pa/Nb, and Nb/P1. Under 2 vol% of sevoflurane, MLAEPs were severely attenuated or abolished. Based on these observations, > or = 1.5 vol% sevoflurane should suppress phenomena such as auditory perceptions, intraoperative wakefulness, and awareness.
Adult↗
Selective pulmonary vasodilation by inhaled prostacyclin in a newborn with congenital heart disease and cardiopulmonary bypass.
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Administration, Inhalation↗
Inhalation anaesthesia at the extremes of age: geriatric anaesthesia.
No single anaesthetic technique is superior for all elderly patients, although the prognosis is improved if minor surgical procedures are performed with local anaesthesia rather than with general or major regional anaesthesia. If general anaesthesia is required, which specific inhalation anaesthetic can improve the prognosis of the geriatric patient? The low solubility of desflurane and its resistance to biodegradation would seem to recommend its use in the geriatric patient. However, these theoretical advantages remain to be adequately documented.
Aged↗
Thermodilution cardiac output may be incorrect in patients on venovenous extracorporeal lung assist.
Cardiac output measurement is part of routine monitoring in critically ill patients. In patients on extracorporeal lung assist, thermodilution cardiac output measurement may lead to erroneous results caused by indicator loss into the extracorporeal circuit. Seven patients on venovenous extracorporeal lung assist were studied using different extracorporeal blood flows. We compared conventional thermodilution cardiac output determinations with dye dilution cardiac output measurement, with dye injection into the pulmonary artery. The latter method is not affected by the extracorporeal circuit. The conventional thermodilution method overestimated cardiac output up to a maximum of 300%, providing results up to 10 L/min higher than true cardiac output. The mean difference between thermodilution and true cardiac output as determined by dye dilution with pulmonary artery indicator injection was 3.0 +/- 2.41 L/min. There was no correlation between thermodilution cardiac output values and true cardiac output (r = 0.06). We conclude that conventional thermodilution is not a suitable method for cardiac output measurement in patients on extracorporeal lung assist, especially if high extracorporeal blood flows are applied.
Adult↗
[Preoperative patient education in plastic surgery].
Federal guidelines requires written informed consent for each operation. The patient has to be informed about important facts concerning the treatment. The specific risks always have to be mentioned in detail. If the patient is not able to agree expressly because of his serious injury, he can be treated without express consent. The extent of the preoperative information depends on the indication: the more urgent the treatment, the less detailed the amount of information and vice versa.
Germany↗
Mid-latency auditory evoked potentials and wakefulness during caesarean section.
We investigated intra-operative wakefulness and mid-latency auditory evoked potentials (MLAEP) in 20 patients undergoing elective Caesarean section under general anaesthesia. Anaesthesia was induced with thiopentone 5 mg kg-1 i.v. and succinylcholine 1-1.5 mg kg-1 i.v. After delivery, a balanced anaesthetic technique was maintained using fentanyl 0.2-0.3 mg i.v., enflurane 0.4-1.0 vol% end-expired concentration and 50% N2O in oxygen. Purposeful movements were interpreted as signs of inadequate anaesthesia and intra-operative wakefulness. They were recorded as either spontaneous movements or in response to one of two audio tapes (tape A: sound of a crying baby; tape B: classical music). Post-operatively, intra-operative dreams, hallucinations and detailed reports about intra-operative events were evaluated. Auditory evoked potentials were recorded online before and during general anaesthesia. Twenty spontaneous purposeful movements were observed in 12 patients, seven before or during delivery and 13 after delivery. Four purposeful movements were observed after presentation of the sound of a crying baby but only one after classical music. Dreams and hallucinations were reported by nine patients. Two patients reported experiencing surgical manipulations. In the awake state MLAEPs had great peak-to-peak amplitudes and a periodic waveform. Under adequate levels of general anaesthesia MLAEPs showed a marked increase in latency and decrease in amplitude or were even suppressed completely. This increase in latencies and decrease in amplitude of MLAEP was absent in patients who reported intraoperative events and during spontaneous or provoked motor reactions.
Anesthesia, General↗
[Study of psychopathologic-biorhythm aspects of alcoholic patients in the withdrawal phase--initial results of a pilot study].
There are some works on the psychopathological-biorhythmical situation of alcoholics in their stages of abstinence. Especially the subjectively experience sleeping behaviour was only seldom assessed. The aim of the present examination was to differentiate different types of the course of the postacute abstinence phase. 30 hospitalized alcoholics whose acute withdrawal symptoms were eased took part in prospective study. By means of a test battery the state of mental abilities and sleeping behaviour were registered. The first results point out to a typing of the postacute abstinence phase whose clinical relevance still need further investigations.
Adult↗
Low-dose hydrocortisone infusion attenuates the systemic inflammatory response syndrome. The Phospholipase A2 Study Group.
There is increasing evidence that the hypercortisolemia in inflammatory diseases suppresses the elaboration of proinflammatory cytokines, thus protecting the host from its own defence reactions. In severe sepsis and septic shock cortisol levels are usually elevated, but some patients may have relative adrenal insufficiency. This may contribute to the overwhelming systemic inflammatory response syndrome. We evaluated the impact of low-dose hydrocortisone infusion (10 mg/h) on the course of the systemic inflammatory response syndrome. This dose corresponds to a maximum secretory rate of cortisol achieved in corticotropin-stimulated healthy humans. In a prospective observational study 57 surgical patients with severe sepsis or septic shock were studied, of which in addition to the conventional treatment 12 patients were infused with low-dose hydrocortisone, and 45 were treated without any corticosteroid. In the longitudinal analysis the systemic inflammatory response--as judged by body temperature, cardiovascular response, and kinetics of inflammatory mediators such as phospholipase A2, C-reactive protein, and neutrophil elastase--started to differ in favor of the hydrocortisone-treated patients after 2 days of treatment (P < 0.05, Mann-Whitney U test). The difference disappeared after withdrawal of exogenous cortisol. Shock reversal was achieved in all patients treated with low-dose hydrocortisone. The data provide evidence that low-dose hydrocortisone infusion attenuates the systemic inflammatory response in human septic shock. From an immunological point of view a relative cortisol deficiency may contribute to the amplified immune response in systemic inflammatory diseases. A randomized clinical trial must clarify the impact of low-dose hydrocortisone infusion on the clinical course and outcome of septic shock patients.
Adrenal Insufficiency↗
A novel, remote-controlled suspension device for brain tissue PO2 measurements with multiwire surface electrodes.
A new device was developed for rapid assessment of PO2 values in viable tissue, such as the brain, using a multiwire surface electrode. The instrument utilizes a phonograph-like construction with weightless suspension of the electrode which thus minimizes surface pressure and allows for compensation of brain movements. The new and original component of the present device is the motor-driven, servo-controlled rotation of the PO2 electrode around its vertical axis. This enables PO2 measurements from precisely defined locations. From values measured on rabbit brain surface a PO2 histogram was constructed. The mean PO2 and distribution histogram were similar to those obtained with a needle electrode. The novel device, therefore, enables accurate and fast tissue PO2 measurements with minimal risk of brain damage.
Animals↗