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E Kochs

Publications and source records attributed to E Kochs.

At least 73 records · Page 4Linked to original sources
PubMed1999

Desflurane and isoflurane improve neurological outcome after incomplete cerebral ischaemia in rats.

We have investigated the effects of isoflurane and desflurane on neurological outcome in a rat model of incomplete cerebral ischaemia. We studied 40 non-fasted male Sprague-Dawley rats, anaesthetized, intubated and ventilated mechanically with isoflurane and nitrous oxide in oxygen (FlO2 0.3). Arterial and venous catheters were inserted for measurement of arterial pressure, drug administration and blood sampling. A biparietal electroencephalogram (EEG) was recorded continuously using subdermal platinum electrodes. At completion of surgery, administration of isoflurane was discontinued (with the exception of those animals receiving isoflurane as treatment) and rats were allowed an equilibration period of 30 min according to the following procedure: group 1 (n = 10), 66% nitrous oxide in oxygen and fentanyl (bolus 10 micrograms kg-1 i.v. followed by infusion at a rate of 25 micrograms kg-1 h-1); group 2 (n = 10), 1.0 MAC of isoflurane in oxygen (FlO2 0.3) and air; groups 3 and 4 (n = 10 per group), 1.0 MAC or 1.5 MAC of desflurane in oxygen (FlO2 0.3) and air, respectively. Ischaemia was produced by combined unilateral common carotid artery ligation and haemorrhagic hypotension to 35 mm Hg for 30 min. Functional neurological deficit was evaluated for 3 days after cerebral ischaemia. At baseline, brain electrical activity was higher with fentanyl-nitrous oxide, 1.0 MAC of isoflurane and 1.0 MAC of desflurane (groups 1-3) compared with 1.5 MAC of desflurane (group 4). Neurological outcome was improved in isoflurane and desflurane anaesthetized animals (groups 2-4), regardless of the concentration used compared with fentanyl-nitrous oxide anaesthesia (group 1). The increase in plasma epinephrine and norepinephrine concentrations during ischaemia was significantly higher in fentanyl-nitrous oxide anaesthetized animals (group 1) compared with animals who received volatile anaesthetics (groups 2-4). These data suggest that cerebral protection produced by isoflurane and desflurane appears to be related to reduction in sympathetic activity rather than suppression of cerebral metabolic rate.

Anesthetics, Inhalation↗
PubMed1999

Anesthesia for cesarean section and acid aspiration prophylaxis: a German survey.

UNLABELLED: We surveyed routine anesthetic practice and measures to prevent acid aspiration syndrome (AAS) in patients undergoing cesarean section (CS) throughout Germany. Of 1061 questionnaires, 81.9% were returned. For scheduled CS, general anesthesia was used in 63% of cases, and for urgent CS, it was used in 82% of cases. Regional anesthesia was used less often for both scheduled and urgent CS in smaller (< or =500 deliveries/yr; 28% and 16%, respectively) than in medium-sized (500-1000 deliveries/yr; 42% and 19%, respectively) or major obstetric departments (>1000 deliveries/yr; 45% and 21%, respectively). Among the regional techniques, epidural anesthesia (59%) was preferred more than spinal anesthesia (40%) in scheduled CS. In urgent CS, spinal anesthesia predominated (56% vs 42%). Pharmacological AAS prophylaxis is routinely used in 69% (68%) of departments before elective (urgent) CS under general anesthesia and in 52% under regional anesthesia. H2-blocking drugs are preferred for AAS prophylaxis over H2-blocker plus sodium citrate and sodium citrate alone. Both the incidence of and the mortality from AAS at CS are very low in Germany (<1 fatality per year). Nevertheless, AAS prophylaxis deserves more widespread use in obstetric anesthesia and in other patients at risk (e.g., children, outpatients). IMPLICATIONS: According to a countrywide survey, the use of regional anesthesia for cesarean section and pharmacological prophylaxis of acid aspiration syndrome is considerably less common in Germany than in the United States, United Kingdom, or other European countries.

Anesthesia, Conduction↗
PubMed1999

Middle latency auditory evoked responses and electroencephalographic derived variables do not predict movement to noxious stimulation during 1 minimum alveolar anesthetic concentration isoflurane/nitrous oxide anesthesia.

UNLABELLED: The electroencephalogram (EEG) and middle latency auditory evoked responses (MLAER) have been proposed for assessment of the depth of anesthesia. However, a reliable monitor of the adequacy of anesthesia has not yet been defined. In a multicenter study, we tested whether changes in the EEG and MLAER after a tetanic stimulus applied to the wrist could be used to predict subsequent movement in response to skin incision in patients anesthetized with 1 minimum alveolar anesthetic concentration (MAC) isoflurane in N2O. We also investigated whether the absolute values of any of these variables before skin incision was able to predict subsequent movement. After the induction of anesthesia with propofol and facilitation of tracheal intubation with succinylcholine, 82 patients received 1 MAC isoflurane (0.6%) in N2O 50% without an opioid or muscle relaxant. Spontaneous EEG and MLAER to auditory click-stimulation were recorded from a single frontoparietal electrode pair. MLAER were severely depressed at 1 MAC isoflurane. At least 20 min before skin incision, a 5-s tetanic stimulus was applied at the wrist, and the changes in EEG and MLAER were recorded. EEG and MLAER values were evaluated before and after skin incision for patients who did not move in response to tetanic stimulation. Twenty patients (24%) moved after tetanic stimulation. The changes in the EEG or MLAER variables were unable to predict which patients would move in response to skin incision. Preincision values were not different between patients who did and did not move in response to skin incision for any of the variables. MLAER amplitude increased after skin incision. We conclude that it is unlikely that linear EEG measures or MLAER variables can be of practical use in titrating isoflurane anesthesia to prevent movement in response to noxious stimulation. IMPLICATIONS: Reliable estimation of anesthetic adequacy remains a challenge. Changes in spontaneous or auditory evoked brain activity after a brief electrical stimulus at the wrist could not be used to predict whether anesthetized patients would subsequently move at the time of surgical incision.

Adolescent↗
PubMed1999

Pharmacokinetics and pharmacodynamics of vecuronium in rats with systemic inflammatory response syndrome: treatment with NG-monomethyl-L-arginine.

BACKGROUND: Insufficient detoxification caused by nitric oxide-related inhibition of cytochrome P450 may be important for metabolism of numerous drugs, including vecuronium. The present study investigated the pharmacodynamics and pharmacokinetics of vecuronium in rats with inflammatory liver dysfunction. METHODS: Male Sprague-Dawley rats (n = 56) were randomly allocated into two groups: In the sepsis group, liver inflammation was established by injection of 56 mg/kg heat-killed Corynebacterium parvum; control rats received the solvent. At day 4, groups were subdivided according to treatment with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (250 mg/kg) or placebo. The aminopyrine breath test was performed to assess cytochrome P450 activity. Rats were anesthetized with propofol and mechanically ventilated. Duration of action of vecuronium (1.2 mg/kg) was measured by evoked mechanomyography (stimulation of the sciatic nerve, contraction of the gastrocnemius muscle). In seven rats of each subgroup a 50% neuromuscular blockade was established by a continuous vecuronium infusion. Vecuronium plasma levels were measured and plasma clearance of vecuronium was calculated. Nitric oxide synthesis was assessed by measuring nitrite/nitrate serum levels. RESULTS: In sepsis/placebo rats, vecuronium-induced neuromuscular blockade was prolonged (144% of contro/placebo), vecuronium plasma levels at 50% neuromuscular blockade were increased (122% of control/placebo), and plasma clearance was decreased (68% of control/placebo). N(G)-monomethyl-L-arginine therapy in rats with sepsis improved cytochrome P450 activity and plasma clearance of vecuronium, shortened duration of action of vecuronium, but did not alter the elevated vecuronium plasma levels. CONCLUSIONS: A systemic inflammatory response syndrome with liver dysfunction results in decreased sensitivity to and a decreased elimination of vecuronium. Modulation of nitric oxide synthesis may be a strategy that can be used in the future to improve xenobiotic metabolism in sepsis.

Alanine Transaminase↗
PubMed1998

The NO synthase inhibitors L-Name and L-NMMA, but not L-arginine, block the mammalian nicotinic acetylcholine receptor channel.

(1) Nitric oxide (NO) synthase inhibitors (NOS-I) such as L-Name (N(G)-nitro L-arginine methyl ester) and L-NMMA (N(G)-monomethyl L-arginine) may enhance anesthesia indirectly by inhibiting the NO pathway. Moreover, NOS-I interact directly with receptor proteins. In an animal study, L-NMMA potentiated muscle relaxants. (2) The present experiments investigate the effects of L-NMMA, L-Name, and L-arginine on the nicotinic acetylcholine receptor channel (nAChR) using patch clamp techniques and a piezo-driven application system. Both NOS-I appear to directly interact with the nAChR in the open as well as in the closed conformation. L-Arginine has no effect.

Animals↗
PubMed1998

[Sevoflurane in elderly patients].

An ideal anaesthetic should allow rapid, pleasant, and predictable induction, maintenance and emergence from anaesthesia. Little information is available about sevoflurane use in elderly patients. The pharmacological profile of sevoflurane may be advantageous in geriatric patients because low solubility in the blood is a prerequisite for rapid changes in anaesthetic depth. In addition, the pharmacological profile of sevoflurane may help to reduce the total amount of drug required. Using volatile anaesthetics with low blood solubility and rapid clearance may help in an early postoperative assessment of the neurological status. Because geriatric patients show a higher intraoperative variability of haemodynamic parameters when compared to younger patients a drug such as sevoflurane with rapid uptake and elimination may be advantageous for treatment of hyper- and hypotensive states. As a consequence, the need for vasoactive drugs may be reduced. Recovery from sevoflurane anaesthesia is faster when compared with isoflurane. However, there is still controversy if the occurrence of postoperative cognitive and mental impairment is reduced in elderly patients if drugs with fast elimination characteristics are use. Few data are available on the use of sevoflurane in geriatric patients with renal impairment. Further studies are needed to clarify if the administration of sevoflurane is safe in this population of patients.

Aged↗
PubMed1998

[Anesthesia in cesarean section in the FRG in 1997. Results of a nationwide survey].

A survey of all German hospitals providing obstetric anaesthesia in 1997 (n = 1061, recovery rate 82% comprising 115,000 Caesarean sections revealed that most Caesarean sections (CS) are performed under general anaesthesia (GA). For elective CS, the average was 63%, and 82% for urgent (non-emergency) section. Succinylcholine is the standard neuromuscular blocker for intubation. Of the regional techniques, epidural continuous anaesthesia (ED) is preferred for elective CS (59%) over subarachnoid (SA, 10%) and combined epidural and subarachnoid anaesthesia (CSE). In urgent CS, SA is used more often (56%) than ED (42%) and CSE. With increasing number of births per year, the use of regional techniques is more common.

Anesthesia, General↗
PubMed1998

[Tooth injury during intubation--diagnostic and therapeutic aspects].

This study analysis 16 cases of dental injuries occurring during endotracheal intubation. The overall rate was 1 out of 6000 cases of intubation. As expected, the upper jaw teeth are most often involved. Partial dislocations were the most common lesion, together with dental fractures. A well-documented dental evaluation before delivery of anesthetics and appropriate precautions and protective devices during intubation will prevent most dental trauma related to endotracheal intubation. Also, early use of dental and risk management services often will ensure timely resolution of such problems.

Humans↗
PubMed1998

The effects of sevoflurane on cerebral blood flow autoregulation in rats.

UNLABELLED: In this study, we investigated the effect of sevoflurane on cerebral blood flow (CBF) autoregulation in rats. Twenty-four male Sprague-Dawley rats were randomly assigned to receive one of the following anesthetic treatments. In Group 1 (n = 8, control) anesthesia was maintained using fentanyl (25 microg x kg(-1) x h(-1)) and N2O/O2 (fraction of inspired oxygen 0.33). In Group 2 (n = 8) and Group 3 (n = 8), anesthesia was maintained using 2% sevoflurane (1 minimum alveolar anesthetic concentration [MAC]) and 2 MAC sevoflurane (4 vol%) in O2/air (fraction of inspired oxygen 0.33), respectively. Cortical CBF autoregulation was measured during graded hemorrhage within the mean arterial pressure (MAP) range of 100-30 mm Hg using laser Doppler flowmetry. CBF was constant with fentanyl/ N2O (Group 1) and 1 MAC sevoflurane (Group 2) within the MAP range of 100-40 mm Hg. In Group 3 (2 MAC sevoflurane), CBF decreased as a linear function of hemorrhagic hypotension. These results indicate that CBF autoregulation was intact during 1 MAC sevoflurane. In contrast, CBF autoregulation was impaired with 2 MAC sevoflurane. This is probably related to a reduction of baseline cerebrovascular tone with higher concentrations of sevoflurane, which results in a decreased capacity of autoregulatory cerebrovascular dilation during hemorrhage. IMPLICATIONS: The purpose of the present study was to investigate the effect of sevoflurane on cerebral blood flow autoregulation in rats. Cerebral blood flow autoregulation was intact with 1 minimum alveolar anesthetic concentration sevoflurane but was impaired with 2 minimum alveolar anesthetic concentration sevoflurane.

Anesthetics, Inhalation↗
PubMed1998

Effects of intraabdominally insufflated carbon dioxide and elevated intraabdominal pressure on splanchnic circulation: an experimental study in pigs.

BACKGROUND: Intraabdominally insufflated carbon dioxide (CO2) during laparoscopy may have a specific effect on splanchnic circulation that may be unrelated to the effects of increased intraabdominal pressure alone. Therefore, the influences of insufflation with CO2 versus air on splanchnic circulation were compared. METHODS: Pigs were chronically instrumented for continuous recording of mesenteric artery, portal venous, inferior vena cava, and pulmonary arterial blood flow and portal venous pressure. After induction of anesthesia, CO2 or air was insufflated in 14 and 10 pigs, respectively. With the pigs in the supine position, intraabdominal pressure was increased in steps of 4 mmHg up to 24 mmHg by graded gas insufflation. RESULTS: During air insufflation, mesenteric artery vascular resistance was unchanged, whereas mesenteric arterial blood flow decreased with increasing intraabdominal pressure. Shortly after CO2 insufflation to an intraabdominal pressure of 4 mmHg, mean arterial pressure, mesenteric arterial blood flow, and mesenteric arterial vascular resistance were increased by 21%, 12% and 9%, respectively. Subsequently, with the onset of CO2 resorption in the third minute, mean arterial pressure declined to baseline values and mesenteric arterial vascular resistance declined to 85% of baseline values, whereas mesenteric arterial blood flow continued to increase to a maximum of 24% higher than baseline values. At steady-state conditions during CO2 insufflation, mesenteric arterial blood flow was increased up to an intraabdominal pressure 16 mmHg but decreased at higher intraabdominal pressures. CONCLUSIONS: In contrast to air insufflation, intraabdominal insufflation of CO2 resulted in a moderate splanchnic hyperemia at an intraabdominal pressure < or = 12 mmHg. At higher intraabdominal pressure values, pressure-induced changes became more important than the type of gas used.

Abdomen↗
PubMed1998

Monitoring of the central nervous system.

Clinical studies have shown a close relationship between variables such as hypoxia, increased intracranial pressure, arterial hypotension, or seizures and neurological outcome. This indicates the need for monitoring techniques of the central nervous system including measurements of cerebral blood flow, cerebral oxygenation and neuronal function. Semiquantitative changes in cerebral blood flow can be measured continuously using transcranial Doppler sonography. Measurements of jugular venous oxygen saturation or tissue oxygenation reflect the balance between cerebral oxygen delivery and cerebral oxygen demand. Near-infrared spectroscopy appears to be a technology with potential for non-invasive measurements of cerebral oxygen saturation and mitochondrial oxygen availability. The current technology is, however, of limited clinical utility. Brain electrical monitoring techniques such as electroencephalogram and evoked potentials are sensitive and specific to detect changes in neuronal function caused by cerebral ischaemia. Electroencephalogram and evoked potential measurements of depth of anaesthesia and specific electroencephalogram patterns for pharmacodynamic quantification of drug effects may gear the dosage of anaesthetics according to the anaesthetic effect.

Journal Article↗
PubMed1998

Correlation of transcranial Doppler sonography mean flow velocity with cerebral blood flow in patients with intracranial pathology.

Several studies suggest that relative changes in cerebral blood flow (CBF) may be assessed via transcranial Doppler sonography (TCD). The present study investigates the correlation between changes in TCD-mean flow velocity (Vm) and changes in CBF in patients with a variety of types of intracranial pathology undergoing cerebrovascular reactivity tests. After informed consent was obtained, 32 patients presenting with stenoses of brain-supplying arteries (n = 13), cerebral vascular malformations (n = 6), surgical decompression for subarachnoid hemorrhage (n = 2), brain edema after closed head injury (n = 8), or hepatic encephalopathy (n = 3) were studied. The patients were divided into two groups for different reactivity tests. Patients in group 1 (awake or sedated, n = 18) received a 1-g dose of acetazolamide intravenously. In group 2 (n = 14), mechanical ventilation was adjusted to produce a 20% decrease in arterial CO2 tension compared with baseline. Regional CBF was measured using xenon-enhanced computed tomography (Xe-CT). Xe-CT scans at the levels of the basal ganglia and the lateral ventricles were performed during a 4.5-min xenon wash-in period. Bilateral flow velocity was measured in the middle cerebral artery using a 2-MHz pulsed TCD system. Mean arterial blood pressure, heart rate, and end-tidal CO2 were continuously recorded during the procedure. After baseline measurements and either alteration of CO2 or application of acetazolamide, the cerebrovascular reactivity was assessed at 20 min by a second measurement of CBF, TCD, and all other physiologic variables. The correlation coefficient for relative changes of MCA territory CBF versus Vm and for the overall population was r = 0.82. In groups 1 and 2, the r values were 0.39 and 0.5, respectively. Correlation coefficients did not exceed r = 0.4 in any subgroup-classification based on diagnosis. The close correlation between changes in CBF and Vm (r = 0.82) in patients with heterogeneous intracranial pathology seems to show that TCD is a measure of CBF. However, in groups 1 and 2 and in subgroups formed of patients classified according to diagnoses, data dispersion suggests that the actual correlation is weaker. Relation of changes in Vm to those in CBF may depend on the underlying diagnosis. These data indicate that the correlation between Vm and CBF may vary with intracranial pathology.

Acetazolamide↗
PubMed1998

Subarachnoid and intravenous PCA versus bolus administration for postoperative pain relief in orthopaedic patients.

BACKGROUND: Patient-controlled analgesia (PCA) with intravenous piritramide and subarachnoid bupivacaine was studied during postoperative pain management in comparison with nurse-administered bolus injections. METHODS: Following general anaesthesia (n = 60) patients randomly received either 3.75-7.5 mg i.v. piritramide on demand (group P-Bolus) or via PCA (group P-PCA; initial bolus: 3.75 mg i.v. piritramide, baseline rate: 1 mg/h, demand-dose 1.5 mg, lockout time: 20 min). Following continuous spinal anaesthesia (n = 60; CSA; 28-G spinal catheter) patients randomly received a subarachnoid injection of 1.5 ml bupivacaine 0.25% every 2-4 h (group B-Bolus) or a baseline infusion of 0.5 ml/h bupivacaine 0.125% plus 0.5 ml bupivacaine 0.125% on demand via PCA (group B-PCA; lockout time: 30 min). Pain ratings were assessed hourly by patients using a visual analogue scale (0 = no pain, 100 mm = unbearable pain). STATISTICS: multivariate analysis of variance. RESULTS: While pain scores did not differ between group P-Bolus and P-PCA, group B-PCA showed the lowest pain ratings (18 +/- 22 mm) differing significantly from group B-Bolus (41 +/- 32 mm; P < 0.001). Group P-PCA required more piritramide than group P-Bolus (46 +/- 15 mg vs. 31 +/- 13 mg, P = 0.001). In contrast group B-PCA required less bupivacaine than group B-Bolus (18 +/- 4 vs. 23 +/- 7 mg, P = 0.002). CONCLUSION: PCA with CSA was more effective than nurse-administered bolus-administration of bupivacaine, while the present study failed to show superiority of i.v. PCA over i.v. bolus-administration of piritramide. PCA using the subarachnoid route is a promising concept for treatment of postoperative pain in orthopaedic patients, while the PCA piritramide regime of this study warrants improvement.

Aged↗
PubMed1997

[Does anesthesia always involve analgesia?].

The primary aim of anesthesia is the prevention of pain perception (analgesia), intraoperative awareness (hypnosis), and postoperative recall (amnesia) (anesthetic trade). Analgesia would be a component of the anesthetic state. Pain is the conscious perception of a noxious stimulus and analgesia is the abolished perception of pain in an otherwise conscious patient. During general anesthesia pain can not be experienced, since the patient is unconscious. However, there is no certainty that during anesthesia a blockade of the nociceptive system is reliably provided in all circumstances. The impact of insufficient blockade of nociceptive pathways during anesthesia on mental status and implicit memory are largely unknown. Therefore, the anesthetic trade should consist of hypnosis, amnesia and antinociception.

Analgesia↗
PubMed1997

Changes in tumor oxygenation during a combined treatment with fractionated irradiation and hyperthermia: an experimental study.

PURPOSE: To determine the influence of adjuvant hyperthermia on the oxygenation status of fractionated irradiated tumors. METHODS AND MATERIALS: Oxygen partial pressure (pO2) in rat rhabdomyosarcomas (R1H) was measured sequentially at weekly intervals during a fractionated irradiation with 60Co-gamma-rays (60 Gy/20f/4 weeks) in combination with local hyperthermia (8 f(HT) at 43 degrees C, 1 h/4 weeks). Tumors were heated twice weekly with a 2450 MHz microwave device at 43 degrees C, 1 h starting 10 min after irradiation. The pO2 measurements (pO2-histograph, Eppendorf, Germany) were performed in anesthetized animals during mechanical ventilation and in hemodynamic steady state. All tumor pO2 measurements were correlated to measurements of the arterial oxygen partial pressure (paO2) determined by a blood gas analyzer. RESULTS: The oxygenation status of R1H tumors decreased continuously from the start of the combined treatment, with increasing radiation dose and number of heat fractions. In untreated controls a median tumor pO2 of 23 +/- 2 mmHg (mean +/- SEM) was measured. Tumor pO2 decreased to 11 +/- 2 mmHg after 30 Gy + 4 HT (2 weeks), and to 6 +/- 2 mmHg after 60 Gy + 8HT (4 weeks). The increase in the frequency of pO2-values below 5 mmHg and the decrease in the range of the pO2 histograms [delta p(10/90)] further indicated that tumor hypoxia increased relatively rapidly from the start of combined treatment. After 60 Gy + 8HT 48 +/- 5% (mean +/- SEM) of the pO2-values recorded were below 5 mmHg. CONCLUSIONS: These findings suggest that adjuvant hyperthermia to radiotherapy induces greater changes in tumor oxygenation than radiation alone [cf. (39)]. This might be of importance for the temporary application of hyperthermia in the course of a conventional radiation treatment.

Animals↗
PubMed1997

[Effects of ketamine on CNS-function].

The present review summarises the main actions of racemic ketamine and ketamine enantiomers on central nervous system receptors. The primary CNS action of ketamine appears to be a non-competitive block of N-methyl-D-aspartate receptors. Although numerous other receptors (e.g., GABA, nicotinic acetylcholine, opiate, voltage-operated channels) have been reported to interact with ketamine, their role in inducing dissociative anaesthesia is still under discussion. In humans, characteristic electroencephalographic (EEG) changes after administration of ketamine are dose-dependent increases in delta, theta, and beta power. In equipotent doses S-(+)-ketamine induces similar EEG changes. However, in comparison to racemic ketamine and S-(+)-ketamine, R-(-)-ketamine does not suppress the EEG to the same extent. Former studies suggested that ketamine is a proconvulsive agent; however, recent studies have demonstrated anticonvulsive and even neuroprotective properties. In humans, low-dose ketamine has no influence on early cortical peaks of somatosensory evoked potentials (SEP). Larger doses induce increases in SEP amplitude while latencies are unchanged. Recent data indicate that analgesia induced by low-dose ketamine may be quantitated by specific pain-related SEP. Significant reductions of pain-induced cortical potentials may be correlated with subjective pain ratings. Brain-stem auditory evoked potentials (AEP) are not influenced by ketamine. Interestingly, in contrast to many other anaesthetics, middle-latency AEP were not altered by racemic and S-(+)-ketamine. This observation may indicate insufficient suppression of auditory stimulus processing during ketamine anaesthesia. Motor evoked responses to transcranial electrical or magnetic stimulation in humans are not markedly suppressed by ketamine.

Anesthetics, General↗