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Biomedical subjects

K Taeger

Publications and source records attributed to K Taeger.

At least 37 records · Page 2Linked to original sources
PubMed2000

Less adrenergic activation during cataract surgery with total intravenous than with local anesthesia.

BACKGROUND: Previous studies reported that, contrary to local anesthesia, cataract surgery under inhalational anesthesia is associated with substantial adrenergic activation. We tested the hypothesis that total intravenous anesthesia (TIVA) with propofol and alfentanil produces less or comparable adrenergic activation during cataract surgery than local anesthesia. METHODS: Patients were randomly assigned to peribulbar local block (n=10) or TIVA (n=10). The heart rate, blood pressure, plasma concentrations of catecholamines, cortisol, and glucose were assessed at seven pre-, intra-, and post-operative time points. RESULTS: In the patients given local anesthesia, plasma concentrations of epinephrine, norepinephrine and cortisol did not change significantly. In contrast, plasma epinephrine decreased by roughly 66% during TIVA: from 45+/-16 to 15+/-8 pg/ml. Plasma norepinephrine concentration decreased by roughly 50%, from 462+/-265 to a minimum value of 219+/-6 pg/ml and plasma cortisol concentrations decreased by roughly 61%, from 16.4 ng/ml to 6.4 ng/ml. Blood pressure and heart rates remained near baseline values during local anesthesia. In contrast, systolic blood pressure decreased by 30% and heart rate by 12 beats/min during TIVA. CONCLUSION: The presented study and available data clearly suggest that local anesthesia produces the best adrenergic and hemodynamic stability during cataract surgery. Contrary to previously reported results on inhalational anesthesia (thiopentone/enflurane), the TIVA regimen used effectively prevents the adrenergic and metabolic response during cataract surgery.

Adult↗
PubMed2000

Occupational exposure to inhaled anaesthetics: a follow-up study on anaesthetists of an eastern European university hospital.

BACKGROUND: Although no dose-response relationship for the health risks associated with the occupational exposure to inhaled anaesthetics exists, public health authorities recommend threshold values. The aim of the present study was to assess if and to what extent these threshold values are exceeded in an eastern European university hospital before and after measures had been taken to reduce occupational exposure. METHODS: At nine workplaces occupational exposure of anaesthetists to nitrous oxide and halothane or isoflurane was measured by means of photoacoustic infrared spectrometry. The measurements were carried out in 1996 and were repeated in 1997 after the installation of active scavenging devices at five workplaces and an air-conditioning system at one workplace. RESULTS: Occupational exposure to nitrous oxide and halothane or isoflurane was lower in 1997 compared to 1996. In 1997 most of the nitrous oxide values still exceeded the threshold value of 100 ppm, whereas most of the halothane and isoflurane values were already below the threshold values of 5 ppm and 10 ppm in 1996. CONCLUSION: The measures taken were effective in reducing waste gas exposure. Nevertheless, further efforts are necessary, especially for nitrous oxide, to reach western European standards. These efforts comprise structural measures such as active scavenging devices and air-conditioning systems at all workplaces, the use of total intravenous anaesthesia, low-flow anaesthesia and an appropriate working technique.

Anesthesiology↗
PubMed2000

A cytogenetic study on the teaching staff of a polluted school with a questionable increased incidence of malignancies.

Exposure to pollutants, in particular polychlorinated biphenyls (PCB), was established at a school built in 1966. Because of a statistically conspicuous increased frequency of breast cancer observed in the teachers of the school this study was performed to ascertain whether the teachers in the polluted school have an increased level of micronucleated cells (MN) or sister chromatid exchanges (SCE) as an expression of a raised cytogenetic risk. Teachers in a directly adjacent school served as one control group and those from a school about 30 km away as a second one. Each teacher had to answer a questionnaire and after venous blood samples had been taken, the number of MN and SCE in peripheral lymphocytes were determined. For the teachers in the polluted school, in addition, the length of stay in the building during the last month and year was recorded. Thereby no correlation with the number of MN and SCE was proven. In comparison with the two control groups, neither the number of MN nor SCE was increased in the teachers of the polluted school. Even if their predictive value for cancer risk assessment is disputed, MN and SCE have a high rating as standard procedures in the proof of an exposure to genotoxic agents. This study thus does not provide any evidence that, for the teachers in the polluted school, a relevant exposure to genotoxic agents exists.

Adult↗
PubMed2000

Oral preanaesthetic medication for children: double-blind randomized study of a combination of midazolam and ketamine vs midazolam or ketamine alone.

Anxiolysis and sedation with oral midazolam are common practice in paediatric anaesthesia. However, good or excellent results are seen in only 50-80% of cases. For this reason, we investigated if addition of a low dose of oral ketamine (MIKE: ketamine 3 mg kg-1, midazolam 0.5 mg kg-1) resulted in better premedication compared with oral midazolam 0.5 mg kg-1 or ketamine 6 mg kg-1 alone, in a prospective, randomized, double-blind study. We studied 120 children (mean age 5.7 (range 2-10) yr) undergoing surgery of more than 30 min duration. After oral premedication in the ward and transfer, the child's condition in the induction room was evaluated by assigning 1-4 points to the quality of anxiolysis, sedation, behaviour at separation from parent and during venepuncture (transfer score). On days 1 and 7 after operation, parents were interviewed for changes in behaviour (eating, sleep, dreams, toilet training), recollection and satisfaction, using a standardized questionnaire. The groups were similar in age, sex, weight, intervention and duration of anaesthesia. The transfer score was significantly better in the MIKE group (12.5 (95% confidence interval (CI) 11.9-13.1)) than in the ketamine or midazolam groups (10.6 (9.8-11.4) and 11.5 (10.7-12.3), respectively). Success rates for anxiolysis and behaviour at separation were greater than 90% with the combination, approximately 70% with midazolam and only 51% with ketamine alone. The incidence of salivation, excitation and psychotic symptoms was low in all groups. Vertigo and emesis before induction were significantly more frequent after ketamine premedication. During recovery, there were no differences in sedation or time of possible discharge. After 1 week, parents reported nightmares (ketamine five, midazolam three, MIKE one), restless sleep (five/four/four) or negative memories (three/four/one). There were no major or continuing disturbances in behaviour or development. In summary, significantly better anxiolysis and separation were observed with a combination of ketamine and midazolam, even in awake children (sedation was not successful according to the preset criteria), than with midazolam or ketamine alone. Duration of action and side effects of the combination were similar to those of midazolam. The combination of both drugs in strawberry flavoured glucose syrup (pH 4.5 approximately) is chemically stable for 8 weeks.

Anesthesia Recovery Period↗
PubMed2000

Pharmacokinetics of human cerebral opioid extraction: a comparative study on sufentanil, fentanyl, and alfentanil in a patient after severe head injury.

BACKGROUND: The pharmacodynamic differences in time to onset and dissipation of effect of sufentanil, fentanyl, and alfentanil probably result from different rates of blood-brain equilibration. The authors investigated this hypothesis in humans. METHODS: After simultaneous central venous bolus application of sufentanil (10 microg), fentanyl (100 microg), and alfentanil (1,000 microg), arterial and jugular bulb blood samples were drawn simultaneously at 20, 30, 45, 60, 75, 90, 105, 120, 140, 160, 180, 210, 240, 300, 360, and 420 s from 19 patients during the postacute stage of head injury with normal intracranial pressure, cerebral perfusion pressure, and cerebral oxygen metabolism during normocapnia. RESULTS: Peak brain concentration, indicated by equilibrium between arterial and jugular bulb opioid concentrations, was achieved for alfentanil at 45 s, for sufentanil at 5 min, and for fentanyl at 6 min. The corresponding median time intervals (fifth and ninety-fifth percentiles) to reach 50% of peak brain concentration were 15 (14-18), 25 (18-38) and 35 (25-45) s, respectively. Uptake was highest 20 s after bolus and decreased continuously for fentanyl and sufentanil, whereas alfentanil uptake was biphasic. The ratio of the relative amounts of sufentanil, fentanyl, and alfentanil retained in the brain at peak brain concentration was 1x:x6x:x90. CONCLUSIONS: The differences in the time lag between changes in serum concentrations and drug effect after bolus application of nearly equipotent doses of sufentanil, fentanyl, and alfentanil originate from the different times required to reach blood-brain equilibration, mainly depending on different levels and different time profiles of arterial blood concentrations caused by the different tissue distribution volumes.

Adolescent↗
PubMed2000

Anaesthesia for magnetic resonance imaging/computed tomography.

The need for general anaesthesia for magnetic resonance imaging/computed tomography investigations can be reduced by the implementation of structured sedation programmes supervised by anaesthetists. Despite its side-effects, chloral hydrate is still the drug most widely used. Rectal thiopental or intravenous propofol are suggested anaesthetic agents for pre-school children and uncooperative or claustrophobic individuals. Spiral computed tomography scans and ultrafast magnetic resonance imaging shorten immobilization times further. However, functional magnetic resonance imaging and intervention techniques in neuroradiology depend on a motionless patient. A useful strategy for testing anaesthesia equipment has been outlined.

Journal Article↗
PubMed1999

Protein binding of piritramide: influence of various protein concentrations and the postoperative acute phase response.

OBJECTIVE: Piritramide is a lipophilic opioid, which is widely used for postoperative analgesia and analgosedation in Europe. In this study we investigated the influence of various protein concentrations (total protein, alpha1-acid glycoprotein, albumin) and the postoperative acute phase response on the protein binding of piritramide. METHODS: The influence of various protein concentrations on the protein binding of piritramide was investigated by either diluting the serum samples of five volunteers with isotonic saline or by adding different amounts of alpha1-acid glycoprotein. Albumin binding was measured in a 5% human albumin solution. The impact of the postoperative acute phase response was investigated by obtaining daily serum samples from 18 surgical patients until the third postoperative day, and measuring piritramide protein binding, alpha1-acid glycoprotein, total protein and albumin. RESULTS: There was a significant relationship between piritramide protein binding and the concentrations of total protein and alpha1-acid glycoprotein. The binding to albumin was 88%. During the postoperative acute phase response, the protein binding of piritramide did not change. Serum concentrations of alpha1-acid glycoprotein increased, whereas total protein and albumin decreased. CONCLUSION: Although there were significant changes in the piritramide-binding proteins, alpha1-acid glycoprotein and albumin, during the postoperative acute phase response, the protein binding of piritramide did not change. Therefore, a change in protein binding, which might be one factor to be considered in determining piritramide dosage in the postoperative period, does not have to be taken into account.

Acute-Phase Reaction↗
PubMed1999

Blood irradiation for intraoperative autotransfusion in cancer surgery: demonstration of efficient elimination of contaminating tumor cells.

BACKGROUND: Intraoperative blood salvage is contraindicated in cancer surgery because of contaminating tumor cells and the risk of systemic dissemination. On the basis of the radiosensitivity of cancer cells, irradiation of salvaged blood with 50 Gy is proposed as a way to allow return of salvaged blood. STUDY DESIGN AND METHODS: Elimination of tumor cells by blood irradiation was studied in vitro with cells from 10 cell lines and from 14 tumor preparations after their addition to red cells in high numbers, or with blood shed during cancer surgery. Before and after gamma radiation, tumor cells were isolated by density gradient centrifugation and tested for their proliferative capacity in a cell colony assay. DNA metabolism was analyzed by incorporation of 5' bromodesoxyuridine. RESULTS: Survival curves of cells from various tumors confirmed D0 (the dose required to reduce the fraction of surviving cells to 37 percent of the original value) values in the range of 1.2 to 2.2 Gy. After irradiation of tumor cell-contaminated blood with 50 Gy, no cell colony formation was observed, which indicates a reduction rate exceeding 10 log. Irradiated cancer cells showed viability, but no residual DNA metabolism. CONCLUSION: The level of inactivation by a 50-Gy dose far exceeds that needed to inactivate the number of proliferating tumor cells observed or expected in wound blood. These results provide the experimental basis for the clinical application of blood irradiation for intraoperative blood salvage in cancer surgery.

Blood↗
PubMed1999

Augmentation of the rocuronium-induced neuromuscular block by the acutely administered phenytoin.

BACKGROUND: The effects of an acute administration of phenytoin on the magnitude of the rocuronium-induced neuromuscular block were evaluated. METHODS: Twenty patients (classified as American Society of Anesthesiologists physical status I or II) scheduled for craniotomy were studied: 15 received phenytoin during operation (10 mg/kg), and the others served as controls. Anesthesia was induced with thiopental and fentanyl and maintained with nitrous oxide (65%) in oxygen and end-tidal isoflurane (1%). The ulnar nerve was stimulated supramaximally and the evoked electromyography was recorded using a neuromuscular transmission monitor. Continuous infusion of rocuronium maintained the neuromuscular block with first twitch (T1) between 10 and 15% for 45 min before the start of an infusion of either phenytoin or NaCl 0.9%. Twitch recordings continued for 60 min thereafter. Arterial blood samples were collected at the predefined time points (four measurements before and four after the start of the infusion) to determine the concentrations of phenytoin and rocuronium and the percentage of rocuronium bound to plasma proteins. RESULTS: The first twitch produced by an infusion of rocuronium remained constant during the 15 min before and the 60 min after the start of the saline infusion. After the phenytoin infusion, the twitch decreased progressively, but the plasma concentrations and the protein-bound fraction of rocuronium did not change. CONCLUSION: Phenytoin acutely augments the neuromuscular block produced by rocuronium without altering its plasma concentration or its binding to plasma proteins.

Adult↗
PubMed1999

Elimination of methohexitone after long-term, high-dose infusion in patients with critically elevated intracranial pressure.

OBJECTIVE: To determine the plasma elimination of methohexitone in patients with critically elevated intracranial pressure (ICP) who received the drug in high doses for several days. DESIGN: Drug-monitoring study. SETTING: Intensive care unit at a university hospital. PATIENTS: Twelve intensive care unit patients with brain injuries who received methohexitone as a final therapeutic approach after routine therapy had proved to be insufficient in controlling critically elevated ICP. MEASUREMENTS AND MAIN RESULTS: Plasma samples were taken during methohexitone infusion, before cessation, and in distinct, short increments after discontinuation of the infusion. Methohexitone was determined in plasma by reverse-phase high-pressure liquid chromatography and photometric detection. The median duration of infusion of methohexitone was 137 hrs (minimum, 27 hrs; maximum, 445 hrs), with a median infusion rate of 62.5 microg/kg/min (minimum, 22.5 microg/kg/min; maximum, 116.2 microg/kg/min). Plasma concentrations of methohexitone at burst suppression under concomitant analgesic sedation ranged from 1.6 to 17.3 microg/mL (median, 4.7 microg/mL). After cessation of methohexitone infusion, the decline of plasma concentrations followed a biexponential function. Clearance rates, volume of distribution at steady state, context-sensitive half-time, and initial and terminal elimination half-times were calculated. Pharmacokinetic data showed remarkable interindividual variability that could not be correlated to the infusion rate, to the duration of the infusion, or to obvious differences in physiology or the disease states of these patients. Even in patients with high plasma concentrations who received the drug for a considerable length of time, the initial decline in plasma concentration was exponential, indicating redistribution. CONCLUSIONS: We conclude that the elimination kinetics of methohexitone after long-term, high-dose infusion in critically ill patients with brain injuries may favor the use of methohexitone over thiopentone for controlling critically elevated ICP by allowing for a more timely neurologic examination after cessation.

Adolescent↗
PubMed1999

[Evaluation of postoperative pain therapy with patient-controlled analgesia from the viewpoint of the patient and nursing staff].

Patient-controlled analgesia has been proven to be an effective technique in postoperative pain management. The aim of our study was to evaluate PCA on general surgery wards. 311 patients and their nurses were questioned about their experiences in using PCA for postoperative pain management. Satisfaction with pain relief judged by both patients and nursing staff, incidence of negative side effects and technical problems were studied. The great majority of patients and nursing staff rated the quality of pain relief as being satisfactory. Incidence of negative side effects was extraordinarily low. There was no respiratory depression observed, technical problems hardly arose. Most of the patients coped very well with operating their PCA-pumps. We conclude that PCA is a safe and effective method in postoperative pain management on surgical wards. Under the condition of regular monitoring of pain intensity, of analgesic consumption, level of sedation and of side effects by trained medical and nursing staff, monitoring of respiration and vigilance is not necessary for the PCA regimen we used.

Adolescent↗
PubMed1998

Nitrous oxide impairs the signaling of neutrophils downstream of receptors.

(1) Nitrous oxide has been shown to impair the oxidative function of neutrophils. (2) To characterize the type and the site of the drug interaction, receptor expression, cytosolic-free calcium, and H2O2 production of neutrophils were assessed using flow cytometry. (3) Nitrous oxide depresses receptor-dependent generation of H2O2 in a concentration-dependent manner. The response upon direct activation of protein kinase C (PKC) was unaffected. (4) No interference was found at the receptor sites, the linked G proteins, and the subsequent release of Ca2+, indicating a localization of the nitrous oxide interaction downstream of receptors and G proteins at or near to PKC.

Anesthetics, Inhalation↗
PubMed1998

Jugular bulb monitoring of cerebral oxygen metabolism in severe head injury: accuracy of unilateral measurements.

To investigate the accuracy of unilateral jugularvenous monitoring, we performed bilateral jugularvenous monitoring in 22 comatose head injured patients. Fiberoptic catheters were placed upstream in both internal jugular veins and advanced into the jugular bulbs. Arterial and bilateral jugularvenous blood samples were obtained simultaneously for in vitro determination of jugularvenous oxygen saturation (SJO2), arterial minus jugularvenous lactate content difference (AJDL) and modified lactate-oxygen-index (mLOI). Ischemia was assumed, if one of the following pathologies occurred at least unilaterally: SJO2 < 55%, AJDL < -0.37 mmol/L, mLOI > 0.08. The mean and maximum bilateral SJO2 differences varied between 1.4% to 21.0%, and 8.1% to 44.3% respectively. The bias and limits of agreement (mean differences +/- 2SD) between paired samples were -0.4% +/- 12.8%. Regarding AJDL bias and limits of agreement were -0.01 mmol/L +/- 0.18 mmol/L. At best 87% of defined ischemic events could be evaluated by monitoring at the side of predominant lesion or, in diffuse injuries, at the side of the larger jugular foramen in CT scan (CT approach). We conclude, due to the wide limits of agreement in bilateral SJO2 and AJDL the reliability of unilateral jugularvenous monitoring in patients with intracranial pathology is questionable. For diagnosing ischemia the CT approach has the highest sensitivity and is therefore recommended.

Brain↗
PubMed1998

[Occupational exposure and environmental pollution: the role of inhalation anesthetics with special consideration of sevoflurane].

There are a number of assays available to study genetic toxicity of inhalation anaesthetics. Those discussed in this review are the Ames Salmonella mutagenesis test and assays for structural chromosome aberrations, micronuclei (MN) and sister chromatid exchanges (SCEs). None of these assays showed abnormalities induced by volatile inhalation anaesthetics. Only Compound A induced a slight increase in the number of SCEs. However, the implications of this in vitro study are unclear. Results of studies focussing on the effects of long-term occupational exposure to inhalation anaesthetics are controversial. Neither harmfulness nor safety of chronic exposure to low concentrations of inhalation anaesthetics have been proven. Although there is no clear evidence of harmfulness, there is general agreement that occupational exposure should be minimized for precautionary reasons. This particularly applies to N2O. Therefore, occupational exposure standards have been established in many countries, though not yet for sevoflurane and desflurane. In Germany, occupational exposure can be kept below the threshold values, when working in operation theatres with a standard air conditioning system, a high-flow scavenging system, low leakage anaesthesia machines and preventative maintenance of equipment. Under these conditions occupational exposure is low even when using laryngeal mask airways and uncuffed tracheal tubes. Sevoflurane is a halocarbon, but is only partially halogenated and the only halogen it contains is fluorine. Sevoflurane, therefore, appears to have an insignificant effect on ozone depletion and its contribution to the greenhouse effect is negligible.

Anesthesiology↗
PubMed1998

[Patient-controlled analgesia. PCA in a three year old child after traumatic amputation].

We report the case of a 3-year-old boy, who received long-term parent-controlled analgesia after traumatic amputation of one leg. He underwent surgery 17 times for a period of 25 days. Parent-controlled analgesia was started four days after admission because analgesia with non-opioid analgetics (acetaminophen) proved to be insufficient. The pump was set to a bolus-dose of 23 micrograms kg-1 piritramide (dipidolor) and a lockout interval of 10 minutes. Permitted maximum cumulative dose in four hours was 5 mg piritramide. There was no continuous infusion of opioid. PCA and possible adverse effects were explained to the mother. A monitoring regimen was used to assess efficacy (pain intensity estimated by the mother), adverse effects (sedation score, occurrence of nausea and vomiting) and piritramide consumption. For fear of side effects opioid administration was insufficient in the beginning. After three days the mother used the PCA effectively and no additional analgesic medication was required. Nausea or other side effects were not observed. After seven days opioid consumption nearly doubled. Apart from tolerance, this might have resulted from the mother's caution in the first days. After 17 days the PCA was discontinued. Oral analgetics (tramadol) controlled the pain adequately. Management of postoperative pain in children is difficult and too often insufficient. PCA is a safe and effective method of providing postoperative pain relief. Feasibility was shown in adolescents and, more recently, in children aged five years and over. Only few reports are available describing long term use of PCA in children younger than five years. Our case suggests that PCA may also be used effectively and safely in children younger than five years, if experienced staff, a monitoring regimen and cooperative and well instructed parents are available.

Amputation, Traumatic↗
PubMed1998

Nitrous oxide impairs the neutrophil oxidative response.

BACKGROUND: Nitrous oxide has been shown inconsistently to impair the oxidative function of neutrophils. The choice of the stimulus, receptor agonists, or stimuli acting independent of receptors seems to determine whether nitrous oxide impairs the oxidative functions, suggesting an interference with the cytosolic signaling of neutrophils. METHODS: Production of hydrogen peroxide by neutrophils was assessed using flow cytometric analysis. N-formyl-methionyl-leucyl-phenylalanine (FMLP), C5a, dioctanylglycerol, and phorbol-12-myristate-13-acetate were used as stimuli. In addition, the expression of receptors for FMLP and the cytosolic-free calcium response of cells were measured. RESULTS: Nitrous oxide depresses C5a- or FMLP-induced generation of reactive oxygen derivatives in a concentration-dependent manner. However, the response with direct activation of protein kinase C was unaffected. Further, the number of FMLP receptors and the cytosolic calcium response were unaffected. Inhibition of the oxidative response was not reversible within the observation period of 4 h. CONCLUSIONS: Nitrous oxide inhibited the intracellular signaling of the investigated G-protein-coupled receptors for chemotactic peptides. No interference of nitrous oxide with reduced nicotinamide adenine dinucleotide phosphate oxidase, the oxidative enzyme system of neutrophils, nor with its activation through protein kinase C was detected.

Adult↗
PubMed1998

Monitoring of cerebral oxygen metabolism in the jugular bulb: reliability of unilateral measurements in severe head injury.

To investigate the reliability of unilateral jugular venous monitoring and to determine the appropriate side, we performed bilateral jugular venous monitoring in 22 head-injured patients. Fiberoptic catheters were placed in both jugular bulbs. Arterial and bilateral jugular venous blood samples were obtained simultaneously for in vitro determination of jugular venous oxygen saturation (SJO2), arterial minus jugular venous lactate content difference (AJDL), and modified lactate-oxygen index (mLOI). Ischemia was assumed if one of the following pathologic values occurred at least unilaterally: SJO2 <54%, AJDL <-0.37 mmol/L, mLOI >0.08. The sensitivity of calculated unilateral monitoring in detecting ischemia was evaluated by comparing the incidence detected unilaterally with that disclosed bilaterally. The mean and maximum bilateral SJO2 differences varied between 1.4% and 21.0%, and 8.1% and 44.3%, respectively. The bias and limits of agreement (mean differences +/- 2 SD) between paired samples were 0.4% +/- 12.8%. There was no significant variation in bilateral SJO2 differences with time. Decreasing cerebral perfusion pressure (r = -0.559, P < 0.001) and arterial PCO2 (r = -0.342, P < 0.001) were associated with increasing bilateral SJO2 differences. Regarding AJDL, the maximum bilateral differences varied between 0.04 mmol/L and 1.52 mmol/L. The bias and limits of agreement were -0.01 +/- 0.18 mmol/L. At best, 87% of ischemic events were disclosed by monitoring on the side of predominant lesion or, in diffuse injuries, on the side of the larger jugular foramen (computed tomographic [CT] approach). We conclude that in severe head injury, even calculated unilateral jugular venous monitoring has an unpredictable risk for misleading or missing data. Therefore, the reliability of unilateral jugular venous monitoring appears suspicious. For diagnosing ischemia the CT approach is recommended.

Adult↗