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Biomedical subjects

E Kochs

Publications and source records attributed to E Kochs.

At least 19 recordsLinked to original sources
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↗
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

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↗
PubMed1997

[Ketamine racemate and S-(+)-ketamine. Cerebrovascular effects and neuroprotection following focal ischemia].

The phencyclidine derivative ketamine is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist with the thalamo-neocortical projection system as the primary site of action. Racemic ketamine consists of the enantiomers S(+)-ketamine and R(-)-ketamine. Racemic ketamine has never been considered an adequate anaesthetic agent in neurosurgical patients since it produces regionally specific stimulation of cerebral metabolism (CMRO2) and increases cerebral blood flow (CBF) and intracranial pressure (ICP). However, recent experiments suggest that both tracemic ketamine and S(+)-ketamine may reduce infarct size in animal models of incomplete cerebral ischaemia and brain injury. This experimental protective effect appears to be related to decreases in Ca++ influx and maintenance of brain tissue magnesium levels due to NMDA and quisqualate receptor blockade by ketamine. Studies in dogs have shown that racemic ketamine (2.0 mg/kg) increases CBF in the presence of the cerebral vasodilator N2O. In contrast, studies in rats without background anaesthesia showed increases in CBF after racemic ketamine (100 mg/kg i.p.). This suggests that the cerebrovascular effects of racemic ketamine are related to the pre-existing cerebrovascular tone induced by background anaesthetics. Cerebrovascular CO2 reactivity was maintained regardless of the baseline cerebrovascular resistance. There are several mechanisms by which racemic ketamine may increase CBF. It induces dose-dependent respiratory depression with consequent mild hypercapnia in spontaneously ventilating subjects. This produces vasodilation due to the intact cerebrovascular CO2 reactivity. Racemic ketamine also induces regional neuroexcitation, which leads to stimulation of cerebral glucose consumption in the limbic, extrapyramidal, auditory, and sensory-motor systems. This regional neuroexcitation with increased CMRO2 produces increases in CBF that can be blocked by infusion of barbiturates or benzodiazepines. However, increases in CBF with racemic ketamine (1 mg/kg) may also occur during normocapnia and without changes in CMRO2. This effect is related to some additional direct cerebral vasodilating potency of racemic ketamine based on a mechanism involving blockade of Ca++ channels. The effects of racemic ketamine on CBF autoregulation have not been investigated systematically. However, studies in rats have shown that CBF autoregulation was maintained with low- and high-dose S(+)-ketamine. Infusion of racemic ketamine alters intracranial volume and ICP. Studies in spontaneously ventilating pigs with and without intracranial hypertension have shown that racemic ketamine (0.5-5.0 mg/kg) produces increases in PaCO2 and ICP. In contrast, identical experiments with mechanical ventilation and controlled PaCO2 showed no changes in ICP following racemic ketamine infusion. This implies that increases in ICP are related to inadequate ventilation with consecutive hypercapnia and increases in intracranial blood volume. However, mechanical ventilation may not be sufficient to control ICP following racemic ketamine. Experiments in mechanically ventilated dogs indicate that racemic ketamine (2 mg/kg) increases cerebral blood volume and ICP even in the presence of normoventilation, a response that is reversible by hyperventilation or the administration of diazepam. Studies in patients have shown that racemic ketamine (2.0 mg/kg) reduces CBF in the presence of cerebral vasodilators like halothane or N2O. In contrast, studies in unanaesthetised humans showed increases in CBF after racemic ketamine (2-3 mg/kg). This observation is consistent with animal studies and suggests that the cerebrovascular effects of racemic ketamine are related to the pre-existing cerebrovascular tone induced by background anaesthetics. Studies in humans with and without intracranial pathology confirm the data from animal experiments. (ABSTRACT TRUNCATED)

Animals↗
PubMed1997

Haemodynamic changes and skeletal muscle oxygen tension during complete blood exchange with ultrapurified polymerized bovine haemoglobin.

OBJECTIVE: The study investigates the effect of continuous blood exchange with ultrapurified, polymerized bovine haemoglobin (UPBH) in comparison to hetastarch on haemodynamics, oxygen transport and skeletal muscle oxygen tension in a canine model. DESIGN: Sixteen anaesthetized beagle dogs underwent haemodilution with lactated Ringer's to a starting haematocrit of 20% followed by progressive blood exchange with 6% hetastarch 200,000/0.5 (HES, group 1) or UPBH (haemoglobin 13 +/- 1 g.dl-1, molecular weight (MW) 32-500,000, group 2) to haematocrit target levels of 15%, 10% and 5% or less. MEASUREMENTS AND RESULTS: Besides haemodynamics, skeletal muscle tissue oxygen tension (tPO2) was measured using a polarographic needle probe. In HES-treated animals, heart rate, cardiac output and blood flow were higher while systemic vascular resistance, systemic and regional arterio-venous oxygen difference (avDO2) and oxygen extraction ratios were lower when compared to the UPBH group. In spite of a higher final haematocrit of 5% in group 1, in comparison to group 2 with 2%, final muscular oxygen uptake (4.7 +/- 4 vs 10.1 +/- 2 ml.min-1) and mean tPO2 (11.8 +/- 2.3 vs 51.1 +/- 2.9 mm Hg) were lower in group 1 than in group 2. While tPO2 histograms were continuously shifted to lower oxygen tensions during progressive haemodilution with HES, UPBH-exchanged animals showed tPO2 histograms shifted to higher values than baseline. CONCLUSION: In spite of vasoconstriction, UPBH provided more haemodynamic stability and enhanced skeletal muscle tPO2 during progressive blood exchange when compared to HES.

Analysis of Variance↗
PubMed1997

[Intraoperative pain stimuli change somatosensory evoked potentials, but not auditory evoked potentials during isoflurane/nitrous oxide anesthesia].

PURPOSE: Evoked potentials are used for intraoperative monitoring to assess changes of cerebral function. This prospective randomised study assesses the influence of surgical stimulation on midlatency components of somatosensory (SEPs) and auditory evoked potentials (AEPs) in anaesthetised patients. METHODS: After approval of the Ethics Committee and written informed consent 36 orthopaedic patients (34 +/- 15 y, 73 +/- 14 kg. 1.71 +/- 0.07 m, ASA I-II) were randomly included in the study. Anaesthesia was induced with 1.5 micrograms/kg fentanyl, 0.3 mg/kg etomidate and 0.1 mg/kg vecuronium. The lungs were intubated and patients normoventilated in steady state anaesthesia with isoflurane (end-tidal 0.6%) and 66% nitrous oxide. 18 patients (group 1) were assigned to the SEP group: median nerve stimulation, recording at Erb, C 6 and the contralateral somatosensory cortex (N20, P25, N35) vs Fz. AEPs were recorded in group 2 (n = 18): binaural stimulation, recording at Cz versus linked mastoid (V, Na, Pa, Nb). Recordings were performed during 30 min before the start of surgery (baseline: BL), at skin incision (SURG1) and at the preparation of the periost (SURG2). Heart rate, mean arterial blood pressure, oxygen saturation, endtidal pCO2 and isoflurane (PetISO) concentrations were registered simultaneously. Data were analysed by one-way analysis of variance. Post hoc comparison were made by Mann-Whitney U-Wilcoxon Rank Sum Test with p < 0.05 significant. RESULTS AND DISCUSSION: During steady state isoflurane anaesthesia surgical stimulation (SURG2) resulted in significant increases of N20 P25 amplitudes compared with BL (BL: 1.4 +/- 0.7 microV; SURG2: 2.0 +/- 0.8 microV; p < 0.05). Latencies of SEPs and midlatency components of AEPs did not change over time. There were no differences in autonomic parameters between SEP and AEP groups. MAP increased from 76 +/- 6 mmHg at BL to 93 +/- 16 mmHg at SURG1 and 96 +/- 17 mmHg at SURG2 (n = 36; p < 0.05). HR increased from BL (60 +/- 8 beats/min) to SURG2 (76 +/- 12 beats/min). Increases of amplitudes of midlatency SEP amplitudes indicate increased nociceptive signal transmission which is not blunted by isoflurane-nitrous oxide anaesthesia. In contrast, unchanged AEPs indicate adequate levels of the hypnotic components of anaesthesia.

Adult↗