[Intratracheal foreign body caused by a sheared endotracheal intubation stylet]. / Intratrachealer Fremdkörper durch eine abgescherte Einführhilfe.

After orotracheal intubation of a 30-year-old man with a flexible tube, a floating foreign body was noticed inside the tube. The subsequent bronchoscopy revealed a second foreign body near the bifurcation of the trachea. Both foreign bodies were removed successfully and identified as parts of the plastic-sheathed stylet. Fatigue of material is discussed as the reason for the broken reusable stylet during intubation.

The unanticipated difficult intubation: rigid or flexible endoscope?

BACKGROUND: Unanticipated difficult intubation occurs with a frequency between 1.5% and 8.5%. The aim of this study was to compare the use of flexible versus rigid endoscopy in such a patient population, with respect to the preparation time and feasibility of each device. METHODS: During a four-year observational period, 116 patients with unanticipated difficult intubation were managed either with the flexible fiberscope (FFI group, n= 57) or the rigid Bonfils endoscope (RBI group, n= 59) on a randomized basis. RESULTS: The time required for preparing and performing the intubation was significantly shorter in the RBI group: median (IQR) 160 s (118-209 s) as opposed to 229 s (162-326 s) in the FFI group (P=0.001). There were no significant differences with respect to endoscopic visibility or quality of the intubation manoeuvre (P>0.1 each). Causes of unanticipated difficult intubation were mainly as follows: restricted movement of the head and neck (39.7%), a Mallampati class > 2 (35.3%), a short neck (31%) or a thyromental distance < or = 5 cm (28.4%). Postoperative complications associated with the intubation maneuver included slight bleeding (FFI = 8.8% vs RBI = 8.5%; NS), technical problems (12.3 vs 10.2%, NS), hoarseness (15.8 vs 15.3%, P=0.946) and dysphagia (5.3 vs 16.9%, P=0.070). CONCLUSION: Both endoscopic techniques enable quick and safe intubation. The Bonfils method could be the method of choice in cases of already relaxed patients with unanticipated difficult conventional laryngoscopy, presuming that the anaesthetist is familiar with this technique. Because the clinical re-evaluation for possible predictors of difficult intubation revealed no unknown new factors, the preoperative examination for anatomical peculiarities and being aware are the best protection against unanticipated intubation problems.

[Anaesthesiological management in orthotopic liver transplantation -- results of a survey]. / Anästhesiologisches Vorgehen bei orthotopen Lebertransplantationen (LTX) -- Ergebnisse einer Umfrage.

OBJECTIVE: Since there is no therapeutical standard for the anaesthesiological approach during liver transplantation (LTX) in Germany at the moment, we have evaluated the current anaesthesiological procedures during LTX. METHODS: All departments of anaesthesiology (n = 24) cooperating with transplantation centers in Germany received a questionnaire via mail regarding following complexes: anaesthesiological methods, anaesthetics, blood components therapy, perioperative monitoring, supportive cardiovascular therapy and staff. RESULTS: The answers (n = 16) showed following results: Balanced anaesthesia with continuous application of opioids was the standard method (80 %). Different volatile anaesthetics as well as different opioids were used, isoflurane (66.7 %) and fentanyl (53.3 %) were the most common. Veno-venous bypass was never or occasionally used (86.7 %). The differentiated use of catecholamines, based on discussions in the last years, was also reflected in the results. Dobutamine/noradrenaline as combination seemed to be the first choice (46.7 %). Whereas there was an accordance with the employment of blood components, there was a large variation in the effectively applied blood products. Aprotinin was given in 60 % of all clinics occasionally, in 20 % every time and in 20 % aprotinine was never used. In most departments > or = 2 anaesthesiologists (80 %) and 1 nurse (53.3 %) were needed for intraoperative observation. Postoperative medical attendance was provided on anaesthesiological as well as surgical guided intensive care units (ICU). Generally accepted was an early extubation after arrival at the ICU (86.7 %). CONCLUSION: Even though there was a consensus in the anaesthesiological approach during LTX some departments still use different procedures. This is the first study that will give a basis for discussion of anaesthesiological approaches during LTX.

Movement of the upper cervical spine during laryngoscopy: a comparison of the Bonfils intubation fibrescope and the Macintosh laryngoscope.

The movements of the upper cervical spine were measured by fluoroscopy in 20 patients during laryngoscopy with the Bonfils intubation fibrescope and the Macintosh laryngoscope. Laryngoscopy with both the Bonfils intubation fibrescope and the Macintosh laryngoscope resulted in significant extension of the cervical spine as compared to the neutral position but this extension was significantly less with the Bonfils intubation fibrescope than with the Macintosh (p = 0.001). However, the atlanto-occipital distance was significantly greater during laryngoscopy with the Bonfils intubation fibrescope (p = 0.002), and the angle between the occiput and C1 differed significantly between the two techniques (p = 0.001). With the Bonfils intubation fibrescope, significantly less extension was also found at the C1/C2 and C3/C4 levels (p = 0.001 and p = 0.049, respectively). There is therefore significantly less movement of the upper cervical spine during laryngoscopy with the Bonfils fibrescope compared with the Macintosh laryngoscope.

[Catecholamine levels in plasma and cerebrospinal fluid of neurosurgical patients with normal and elevated intracranial pressure]. / Plasma- und Liquor-Katecholamin-Konzentrationen neurochirurgischer Patienten mit normalem und erhöhtem Hirndruck.

OBJECTIVE: Catecholamine levels in the plasma and cerebrospinal fluid of 21 neurosurgical patients with hydrocephalus and with normal and elevated intracranial pressure were determined prospectively in a clinical study. METHODS: The study comprised 11 patients with normal intracranial pressure (8 female, 3 male, group 1) and 10 patients with elevated intracranial pressure (6 female, 4 male, group 2). The patients underwent a ventriculo-peritoneal shunt operation, external ventricular drainage or ventriculocisternostomy. The measuring times were set as follows: time 1: pre-operative; time 2: intra-operative; time 3: post-operative. The anaesthetic for the operations was administered as a total intravenous anaesthesia with propofol and alfentanil, muscle relaxation being achieved with rocuronium bromide or cis-atracurium. RESULTS: Measurements of the catecholamine levels (adrenaline, noradrenaline and dopamine) at the three set times revealed an intra-operative fall compared to the initial pre-operative value and a rise in the catecholamine level again after the operation. It is likely that this largely reflects the course of the anaesthetic. The fall in the plasma catecholamine level was much slighter in group with elevated intracranial pressure. But in the group of patients with elevated intracranial pressure the catecholamine levels found in the plasma were much higher than those of the patients without elevated pressure. In the case of adrenaline, it was possible to demonstrate a statistically significant difference at the three measuring times. This suggests that especially the analyzed adrenaline level in the plasma could take on the role of a marker in cases of elevated intracranial pressure. In group 2, with elevated intracranial pressure, the catecholamine levels in the cerebrospinal fluid (CSF) were considerably higher than those in group 1, but the difference did not reach the significance level. The lack of correlation between the catecholamine values in the plasma and CSF described in the literature (comparison of the corresponding values at time 2) was confirmed for noradrenaline and dopamine in patients with elevated intracranial pressure (group 2). In both groups of patients there was a CSF plasma gradient for dopamine at time 2, i. e. the dopamine level was higher in cerebrospinal fluid than in the plasma. CONCLUSION: The study shows that even a slight rise in intracranial pressure without clinically detectable ischaemia may result in elevated plasma and CSF catecholamine levels. Although catecholamine values are not routine parameters, they can be used in developing procedures to protect the brain in neurosurgical patients.

[Anaesthesia for combined pancreatic and renal transplantation in a patient with mitochondrial encepahalomyopathy--a case report]. / Anästhesieführung zur kombinierten Pankreas- und Nierentransplantation bei einer Patientin mit Mitochondriopathie--Ein Fallbericht.

Mitochondrial disorders encompass a group of syndromes produced by genetic defects that disrupt mitochondrial energy production. The impaired mitochondrial energy supply affects nearly all organs and tissues leading to a variable clinical presentation. The possible multisystem involvement complicates the management of anaesthesia and perioperative care. Exact knowledge of the path physiology of mitochondrial diseases may help to avoid perioperative anaesthesiological complications. This report describes the anaesthetic management of a patient with a mitochondrial disorder during combined pancreatic and renal transplantation, and discusses some of the anaesthetic implications of mitochondrial diseases. Due to the potential susceptibility of patients with mitochondrial diseases to malignant hyperthermia, anaesthesia was induced and maintained as total intravenous anaesthesia using propofol, alfentanil and cis-atracurium. In addition, the patient was treated intraoperatively with hydrocortisone (initial bolus of 50 mg followed by a continuous infusion of 4.8 mg/h) and insulin (continuous infusion of 2 IE/h) in order to manage the adrenocortical insufficiency as well as to treat the diabetes mellitus. Using this anaesthetic technique, satisfactory haemodynamic and metabolic conditions were achieved during surgery. The postoperative period, however, was marked by severe respiratory complications.

[The influence of normobaric hyperoxia on hepatic oxygenation--experience with an animal model]. / Der Einfluss von normobarer Hyperoxie auf die lebervenöse Oxygenierung--Erfahrungen mit einem Tiermodell.

We investigated the effect of a ventilation with an FiO2 of 1.0 on arterial and hepatic venous oxygenation in 23 Göttingen minipigs. Under balanced anaesthesia (isoflurane/fentanyl), a fibreoptic catheter was placed into a hepatic vein. The correct position of the tip of the catheter was controlled manually after laparotomy. After measurement of baseline values (arterial and hepatic blood gases, ShvO2), in 13 minipigs normoventilation with an FiO2 of 1.0 was performed for 15 minutes. Thereafter, ventilation was continued with an FiO2 of 0.4. In the control group (n = 10), the animals were oxygenated with an FiO2 of 0.4 permanently. The changes due to hyperoxia were measured in hepatic venous oxygen saturation (ShvbgaO2: from 81.2 +/- 1.43% to 87.5 +/- 1.77%, ShvoximO2: from 82.6 +/- 1.14% to 90.5 +/- 0.90%), arterial (from 217.5 +/- 5.0 mmHg to 467.2 +/- 22.0 mmHg) and hepatic venous (from 51.8 +/- 2.0 mmHg) oxygen partial pressure. We found a correlation between hepatic venous oxygen partial pressure und ShvbgaO2 in the blood (r = 0.84, p < 0.001) and between ShvO2 (ShvbgaO2/ShvoximO2), which was either measured directly in the blood or by a fibreoptic catheter (r = 0.6, p < 0.001). Whereas the increase in ShvO2 during hyperoxia may be a result of increased arterial supply, the decrease in ShvO2 after the end of hyperoxia below baseline values needs further investigations. The continuous fibreoptic measurement of ShvoximO2, also under hyperoxic conditions is a valuable parameter for the monitoring of hepatic venous oxygenation.

[Is fiber optic hepatovenous oximetry useful in patients undergoing elective partial liver resection?]. / Eignet sich die fiberoptische Lebervenenoxymetrie als zusätzliches Monitoring bei Patienten mit elektiven Leberteilresektionen?

The validity of continuous measurement of hepatic venous oxygen saturation using a fibreoptic technique was investigated and set in correlation with intermittent measurements of saturation in hepatic venous blood in patients undergoing elective partial liver resection (pLR). Eleven patients (4 m/7 f, average age: 62.6 +/- 11.6 years) were included in the study after approval by the Ethics Committee of the University of Leipzig. A fibre-optic heparinized flow-directed pulmonary catheter (5.5-F) was inserted through the right internal jugular vein into the hepatic vein after induction of balanced anaesthesia (isoflurane/alfentanil). The position of the tip of the catheter was verified by fluoroscopic guidance. The oxygen saturation in the hepatic vein measured by the fibre-optic method and by blood-gas analysis (ShvO2) was compared at nine defined measuring points after in-vivo calibration (baseline). The ShvO2 decreased nonsignificantly from 84.4 +/- 10.4% to 77.1 +/- 19.1% during occlusion of the vessels in the liver hilus (Pringle's manoeuvre). The ShvO2 measured by the fibre-optic method and by blood-gas analysis correlated well (r = 0.815, p < 0.001). The limitations of the method result from artefacts based on surgical manipulations in the portal region (compression of hepatic veins, luxation of the liver). These artefacts can be differentiated by analysis of the pressure curves in the hepatic vein. Nevertheless, fibreoptic hepatovenous oxymetry seems to be a feasible method for continuous monitoring of the ShvO2 under intraoperative conditions in patients undergoing partial liver resection. Ischaemic situations of the liver can be detected and treated early. Additional information can be obtained from analyses of parameters in the hepatovenous blood.

[Is the combination of remifentanil and propopfol suitable for transsphenoid resection of the hypophysis?]. / Eignet sich die Kombination von Remifentanil und Propofol für transsphenoidale Resektionen an der Hypophyse?

In a multi-center trial, the feasibility of combining remifentanil (RF) and target-controlled infusion of propofol (P) for patients undergoing transsphenoidal resection of the pituitary gland was tested. After IRB approval, 74 patients (29 male/45 female) were included in the study. The concentration of RF and the target concentration of P were recorded as were heart rate (HR) and mean arterial blood pressure (MAP). For intubation the RF dosage was 0.26 +/- 0.06 microgram.kg-1.min-1 and the target concentration of P was 3.16 +/- 0.63 micrograms.ml-1. After induction, HR and MAP decreased significantly. The painful events of the operation were preparation of the nasal mucous membrane and penetration of the sella turcica. By adjusting the RF dose to 0.31 +/- 0.09 microgram.kg-1. min-1 and the target concentration of P to 3.48 +/- 1.49 micrograms.ml-1, an increase of HR and MAP above initial values was avoided at this time. Hypotension and bardycardia were treated in eight patients (10.8%) with a vasopressor, in four patients (5.4%) with atropine and in four more patients (5.4%) with a combination of these drugs. Two patients (2.7%) needed antihypertensive therapy. The average time interval between the end of P-TCI and spontaneous breathing was 6 +/- 3 min (median 6 min) and till patients opened their eyes 9 +/- 4 min (median 9 min). After 13 +/- 4 min (median 13 min) the patients became orientated. The average doses of analgetics were 19.5 +/- 19.9 mg piritramide and 1.8 +/- 1.0 g metamizol during the first 12 hours postoperatively. Eight patients (10.8%) did not need any analgetics. We suggest that the combination of RF and P as a "fast track concept" can supplement the repertoire of anaesthetic managements used for transsphenoidal resection of the pituitary gland.

[Comparative studies of patient positioning for lumbar intervertebral disk operation]. / Vergleichende Untersuchungen zur Lagerung bei lumbalen Bandscheibenoperationen.

For surgery on lumbar disks by the posterior route, patients are placed either on a Wilson frame or in genupectoral position. The aim of the prospective study was to record and describe the haemodynamic changes resulting from the patients' position. After written informed consent had been received, 80 neurosurgical patients undergoing lumbar disk surgery were randomly divided into two groups; group I--Wilson frame, group II--genupectoral position. In each group, 20 patients received total intravenous anaesthesia (Alfentanil or Remifentanil, Propofol) and 20 balanced anaesthesia with Isoflurane and Alfentanil or Remifentanil. Haemodynamic parameters (mean arterial pressure--MAP and heart rate--HR) were recorded automatically at three measuring times (MT): firstly, after induction of anaesthesia; secondly, before re-direction; thirdly, after re-direction on the Wilson frame or in the genupectoral position. Induction of anaesthesia did not lead to a significant decrease in MAP (MT 1: 92.5 +/- 15.2 mmHg, MT 2: 89 +/- 13.4 mmHg, n = 80). In group I (n = 40), no significant changes were observed in MAP and HR at MT 3 (p = 0.882, p = 0.051). In comparison to group I, the genupectoral position was associated with significant drops in MAP and HR. The genupectoral position caused a significant decrease in MAP (p < 0.001) and HR (p = 0.016) at MT 3. Our data suggest that body weight or body mass index do not necessarily lead to a preference for one of the two possible positions of the patient. Complications resulting from haemodynamic changes were not seen in either group. We recommend the Wilson frame for neurosurgical lumbar disk surgery in cases of cardiovascular or cerebrovascular disorders. The adaptive capacities in the genupectoral position as a result of the modifying distribution of blood volume are limited in these patients. Furthermore, the dose-dependent effects of different anaesthetics on haemodynamic parameters in these prone positions should be explored.

[Hyperoxia-induced liberation of big-endothelin into jugular venous blood of electric neurosurgical patients]. / Hyperoxie-induzierte Freisetzung von BIG-Endothelin in das jugularvenöse Blut elektiver neurochirurgischer Patienten.

The use of hyperoxia in emergency situations is generally accepted, but the routine and uncritical application of higher oxygen concentrations is criticized. The influence of short-term application of hyperoxia on cerebral oxygenation, cerebral lactate and BIG-endothelin (BIG-ET) was studied. After approval by the Ethics Committee of the University of Leipzig, 22 patients (hyperoxia group n = 16, normoxia, control group n = 6) undergoing an elective craniotomy were included in the study. After induction of a total intravenous anaesthesia (sufentanil and propofol), a fibre-optic catheter was inserted into the bulb of the jugular vein. The inspiratory concentration of oxygen was raised from 0.4 to 1.0 for 15 minutes. Before, during and after hyperoxia, a blood gas analysis and analysis of lactate and BIG-ET were performed from arterial and jugularvenous blood. Hyperoxia caused a significant increase in jugularvenous oxygen saturation (sjO2) from 60.4 +/- 8.8% to 68.6 +/- 10.4% and jugularvenous oxygen content (cjvO2) from 10.27 +/- 2.06 vol% to 11.76 +/- 2.16 vol%. These changes were reversible after the end of hyperoxia. The jugularvenous lactate decreased significantly (9%) from 1.20 +/- 0.48 mmol/l to 1.10 +/- 0.45 mmol/l after the end of hyperoxia. Hyperoxia led to a significant increase in jugularvenous BIG-ET from 3.35 +/- 0.61 pg/ml to a maximum of 3.82 +/- 0.95 pg/ml and a decrease in the arterio-jugularvenous difference of BIG-ET from 0.19 +/- 0.53 pg/ml to a minimum -0.11 +/- 0.32 pg/ml. The changes in lactate and BIG-ET were also seen after the end of the hyperoxia. In the control group (normoxia, FiO2 0.4), no significant changes in sjO2, oxygen content, lactate and BIG-ET were observed. The increase in jugularvenous BIG-ET and the decrease in the arterio-jugularvenous difference of BIG-ET following hyperoxia indicate a higher cerebral release of BIG-ET.

Gross-total surgery of supratentorial low-grade gliomas under intraoperative MR guidance.

BACKGROUND AND PURPOSE: Length of survival of patients with low-grade glioma correlates with the extent of tumor resection. These tumors, however, are difficult to distinguish intraoperatively from normal brain tissue, often leading to incomplete resection. Our goal was to evaluate the effectiveness of intraoperative MR guidance in achieving gross-total resection. METHODS: We studied 12 patients with low-grade glioma who underwent surgery within a vertically open 0.5-T MR system. During surgery, localization of residual tumor tissue was guided by interactive, near real-time imaging. The amount of residual tumor tissue on MR images was evaluated at the point of the operation at which the neurosurgeon would have terminated the procedure under conventional conditions (first control) and again before closing the craniotomy. RESULTS: Significant residual tumor (more than 10% of original tumor volume) was shown in eight patients at the first control condition. The percentage of resection varied from 26% to 100% (mean, 68%) at this time. Twelve tissue samples from seven patients were obtained in areas identified as residual tumor on MR images. In 10 cases, the neuropathologic investigation confirmed the presence of residual low-grade glioma; in two cases, the borderzone of tumor was identified. In evaluating the final sets of images, we found total resection in six cases, over 90% resection in five cases, and 85% resection in one case (mean, 96%). CONCLUSION: Surgical treatment of low-grade gliomas under intraoperative MR guidance provides improved resection results with maximal patient safety.

[Effect of normobaric hyperoxia on parameters of brain metabolism]. / Der Einfluss von normobarer Hyperoxie auf Parameter des Hirnstoffwechsels.

In the literature there is only little information about the influence of hyperoxia on cerebral metabolic parameters. The aim of our study was to examine the effect of increased inspiratory oxygen concentrations on parameters of brain metabolism in elective neurosurgical patients. Ten patients undergoing an elective craniotomy for brain tumour resection were included in the study. The inspiratory oxygen concentration was raised at intervals of 15 minutes from 0.4 to 0.6 to 1.0 before opening the skull under "relative steady state conditions". At five defined measuring points, a blood gas analysis and an analysis of lactate and glucose levels were performed from arterial and jugularvenous blood. The lactate oxygen index (LOI), the arterio-jugularvenous lactate difference (AJDL) and the oxygen content of the arterial (caO2) and jugularvenous (cjO2) blood were calculated. Under increasing levels of FiO2, one can see an increase in sjO2, of jugularvenous oxygen tension (pjO2) and in oxygen content (cjO2). The most important result is the significant decrease (10% from baseline) in jugularvenous lactate at FiO2 1.0, while arterial lactate did not change significantly nor did the following parameters: paCO2, pjCO2, LOI, modified LOI, arterial and jugularvenous glucose. Hyperoxia causes a possible shift to aerobic metabolic situation in the brain reflected by decreased jugularvenous lactate.

[Use of the sitting position in neurosurgery. Results of a 1998 survey in Germany]. / Anwendung der sitzenden Position in der Neurochirurgie. Ergebnisse einer Umfrage aus 1998 in Deutschland.

OBJECTIVES: This 1998 survey was carried out on the use of the sitting position for neurosurgical procedures in the posterior fossa and operations of the craniospinal and cervical spine region by the dorsal approach. In addition, anesthetic management of the sitting position and the compliance with recommendations of the Neuroanesthesia Study Group of the German Society of Anesthesiology and Intensive Care Medicine (DGAI) published in 1995 were investigated and compared to results of a 1995 survey. METHODS: A questionnaire was sent to 152 departments of anesthesiology in Germany providing anesthesia for neurosurgical procedures. 85 institutions (56%) responded to the survey, data from 78 hospitals were enrolled into the study. The sitting position was preferred for posterior fossa surgery by 45% of the neurosurgeons, for craniospinal operations by 35% and for cervical spine surgery by the dorsal approach by 39%. To 97% of the institutions the recommendations of the Neuroanesthesia Study Group of the DGAI were well known, 19% modified their anesthetic approach due to these recommendations. Recommendations of the Study Group on neuro-monitoring, in particular on the use of ultrasound (precordially or transoesophageally) for the detection of venous air embolism were followed by all institutions. 45% of the participants of the study preoperatively undertook diagnostic measures to preclude a probe-patent foramen ovale which predisposes the patient to paradoxical air embolism. CONCLUSIONS: The survey demonstrates that the use of the sitting position in German neurosurgery is still high when compared to other Western countries, but a tendency for decline over last 3 years can be observed from our data. In addition, our data appears to indicate a positive effect of the Study Group's recommendations on anesthetic management of the sitting position in neurosurgery.

[Is the combination of nitrous oxide and hyperventilation in elective neurosurgical operations useful?]. / Ist die Kombination von Lachgas und Hyperventilation bei elektiven neurochirurgischen Operationen sinnvoll?

The use of nitrous oxide (N2O) and hyperventilation (HV) in elective neurosurgery is controversially discussed. The emphasis of the study was to show the effects of N2O and/or moderate hyperventilation (paCO2 31.0 +/- 1.2 mmHg) on parameters of cerebral metabolism: jugularvenous oxygen saturation (SjVO2), cerebral extraction of oxygen (CEO2), arterial jugularvenous difference of oxygen contents (AJDO2), arterial jugularvenous difference of lactate (AJDL) and glucose (AJDGL) and lactate-oxygen index (LOI). The study was approved by the Ethics Committee of the University of Leipzig. Forty patients undergoing an elective craniotomy for brain tumour resection were divided into four groups: group 1: n = 10, N2O + normoventilation (NV), group 2: n = 10, N2O + hyperventilation (HV), group 3: n = 10, O2/air + NV, group 4: n = 10, O2/air + HV. N2O + HV led to a significant decrease in SjVO2 from 68.1 +/- 10.7% to 49.7 +/- 5.6%. O2/Air + HV produced a drop from 67.1 +/- 11.1% to 49.8 +/- 7.7%. CEO2 increased significantly in the group N2O + HV from 30.6 +/- 10.6% to 49.6 +/- 5.5% and in the group O2/Air + HV from 31.7 +/- 11.1% to 50.0 +/- 7.8%. AJDO2 increased significantly in the group N2O + HV from 5.79 +/- 1.54 ml% to maximal 8.49 +/- 1.10 ml% and in the group O2/Air + HV from 5.29 +/- 1.76 ml% to maximal 8.03 +/- 1.76 ml%. In the normoventilation-groups 1 and 3, no significant changes in SjVO2, CEO2 and AJDO2 were observed between MP2 and 4. The parameters AJDL, AJDGL and LOI did not show any significant changes in any of the four groups. The described data represent a reduction of cerebral oxygenation, but deleterious effects caused by cerebral ischaemia could not be observed. Based on our data, hyperventilation and its combination with N2O should not be used routinely in neuroanaesthesia.

[Effect of local anesthetics on hemodynamic effects during Mayfield skull clamp fixation in neurosurgery using total intravenous anesthesia]. / Der Einfluss von Lokalanästhetika auf hämodynamische Effekte beim Anlegen der Mayfield-Klammer in der Neurochirurgie unter totaler intravenöser Anästhesie.

For neurosurgical procedures, the association between insertion of the Mayfield skull clamp and haemodynamic changes is generally recognized. We investigated the protective effect of two local anaesthetic substances (lidocaine and bupivacaine) under the conditions of total intravenous anaesthesia (TIVA) with propofol and alfentanil. Forty-two patients undergoing an elective craniotomy (tumor resection) were included in the study and randomly divided into three groups. All patients were given a total intravenous anaesthesia with propofol and aflfentanil. After induction, the skin areas for the pin were infiltrated with 0.9% sodium chloride (n = 14, control group 1), 1% lidocain (n = 14, group 2) or 0.5% bupivacaine (n = 14, group 3). After an interval of 1 to 2 minutes the pins were inserted. The intra-arterial line was inserted before induction. The haemodynamic parameters heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) were monitored continuously. The haemodynamic parameters were recorded at four set times: (1) after induction of anaesthesia, (2) at the onset of the local anaesthesia, (3) at the insertion of the pin-holder, (4) five minutes after insertion. Insertion of the pins led to a significant increase in HR, SAP, MAP and DAP in the control group. These haemodynamic changes can be reduced by local infiltration with lidocaine or bupivacaine. The effect of both substances was the same in our study. Our results suggest that a significant reduction of the haemodynamic effects caused by insertion of the Mayfield skull clamp can be achieved by the use of local anaesthesia. Total intravenous anaesthesia alone with propofol and alfentanil cannot protect against these haemodynamic stimuli.

N2O-induced hypoxia as a model of hypoxic stress of rat myocardium. An ultrastructural-morphometric study.

A model system consisting of a hypoxia chamber combined with a commercial narcosis apparatus adapted to small animals was used to perform a controlled acute isobaric hypoxia on rats with N2O/O2. Ultrathin sections from the left ventricular wall were analysed qualitatively and quantitatively using a computer-aided morphometric program. Compared with the control the cardiomyocytes exhibited a significant increase of volume densities of cytoplasmic vacuoles, lipid drops, sarcoplasmic reticulum, mitochondria, and degenerated intramitochondrial areas. Hypoxic alterations of microvessels consisted mainly in localized endothelial swelling and perivascular edema, protrusions of the luminal surface and moderate mitochondrial alterations similar to those of cardiomyocytes. Further, the number of plasmalemmal vesicles decreased, and the number of vacuoles increased significantly. The results were confirmed by quantitative histochemistry performed by our group in a parallel study. The model can be recommended for studies concerning protective interventions in hypoxia experiments.

The effect of different ventilation regimes on jugular venous oxygen saturation in elective neurosurgical patients.

Since the concept of hyperventilation on neurosurgical and neurotraumatological patients has been contested, our analysis was aimed at its scrutiny on the basis of easily accessible parameters of perisurgical monitoring. Furthermore, the influence of an improved oxygen supply was tested on hyperventilationally induced cerebral changes and to what extent recommendations could be derived for clinical application. In 50 patients (normoventilation FiO2 = 0.4, 0.6; moderate hyperventilation up to a value of paCO2 = 31 mmHg and FiO2 = 0.4, 0.6 and 0.8), who underwent an elective neurosurgical operation at the central nervous system, a fiberoptical catheter was inserted into the bulb of the jugular vein for the continuous monitoring of the jugular venous oxygen saturation (sjvO2), additionally to the regular measures of perioperative monitoring. Approval for this study was given by the Ethics Committee of the University of Leipzig. At five defined times an analysis of arterial and jugular venous blood gas samples was made and their lactate and glucose concentration determined: 1. Immediately after inducing anesthesia; 2. After dura opening; 3. Sixty minutes after dura opening; 4. At dura closing; 5. Sixty minutes after the end of the operation. The lactate oxygen index (LOI) as well as the cerebral oxygen extraction (CEO2) were calculated from primary data. Hyperventilation with a value of FiO2 = 0.4 leads to a significant decrease of the jugular venous oxygen saturation below 55%. It can be positively influenced by increasing the inspiratory oxygen concentration from 40% to 60%. The CEO2 increases, above values of 42% under a hyperventilation of FiO2 = 0.4. This effect can be reversed by increasing the FiO2 value up to 0.6. Under hyperventilation the LOI reaches 'pre-ischemic' values (LOI > 0.03) prior to dura opening. Further decrease of FiO2 to 0.8 has no positive additional effect. Normoventilation with FiO2 = 0.6 induces a decrease of sjvO2 but also a decrease of LOI. Hyperventilation as a routine procedure during elective neurosurgery shall be applied critically and be combined with an increased inspiratory oxygen concentration if necessary. A longterm normoventilation with increased FiO2 should be avoided.

[The sitting position in neurosurgical operations. Results of a survey]. / Die sitzende Position bei Operationen in der Neurochirurgie. Ergebnisse einer Umfrage.

METHODS: In February 1995 a questionnaire was sent out on perioperative management during neurosurgical operations performed in the sitting position to 136 centres and hospitals within the Federal Republic of Germany that perform neuroanaesthesia. The response rate was 61.02%. Besides the question of perioperative monitoring during neurosurgical operations in the sitting position, we asked about currently used positions for patients during the following neurosurgical operations:posterior fossa, craniospinal and posterior cervical surgery. RESULTS: Of all centres, 32.9% use the sitting position only for posterior fossa and craniospinal surgery. For posterior cervical surgery the sitting and prone positions are favoured by 25.6% of all clinics. Nonspecific basic monitoring (electrocardiogram, pulse oximetry, central venous pressure, invasive or noninvasive arterial pressure) is an accepted standard in all clinics. Capnometry, as a specific monitor for venous air embolism, is used in all centres (100%). Precordial Doppler ultrasound (US) monitoring is used in 69.2% of all clinics; 3.8% use transoesophageal Doppler US as a diagnostic method for venous air embolism. DISCUSSION: The sitting position is the preferred position for posterior fossa and craniospinal surgery in neurosurgical patients in Germany. For posterior cervical surgery the German centres use both the sitting and prone positions. Alternative positions like the lateral or the "park-bench" positions are hardly ever used. The essential monitoring devices for neurosurgical operations in the sitting position, as recommended after the survey by the German Society for Anaesthesiology and Intensive Care Medicine (DGAI) in 1995, are predominantly used. However, the use of Doppler US (precordial or transoesophageal) for the detection of venous air embolism and the preoperative diagnosis of a persistent foramen ovale is not yet widespread. CONCLUSIONS: To determine the effect of the recommendations by the DGAI on clinical practice, the survey will be repeated in 1997.