AIM: Previous studies using EEG for assessment of depth of anaesthesia correlate anaesthetic concentration with the anaesthetic stage. This procedure neglects the well known effect of individual different susceptibility to anaesthetics. Thus, patients receiving similar concentrations of anaesthetics may not necessarily be at the same level of "anaesthetic depth". The aim of this study was to define an interindividual comparable level of anaesthesia by recording the autonomic cardiovascular reaction to a standardised painful stimulus (tetanic stimulus, 80 mA, 100 Hz). METHODS: In 61 patients undergoing orthopaedic surgery general anaesthesia was performed with isoflurane in 66% N2O. Starting from 0.4% isoflurane, endtidal isoflurane concentration was increased in a stepwise manner (0.1% isoflurane) until the patient did not show any relevant cardiovascular reaction (increase of heart rate and/or blood pressure < 10%) after tetanic stimulation of the ulnar nerve. If patients demonstrated no haemodynamic changes at 0.4% isoflurane, the concentration was decreased until a relevant cardiovascular reaction was registered. During each steady state period multichannel EEG was recorded and mean values of power density (median: microV2/Hz) were computed. RESULTS: Comparing EEG-results between both groups exhibiting a cardiovascular reaction (CVR+ , median endtidal Iso: 0.5%) and without reaction (CVR- , median endtidal Iso: 0.6%) an increase in low frequency bands and a significant decrease in high frequencies was found (Wilcoxon-test, p < 0.05). In contrast, comparing EEG-data only in relation to endtidal isoflurane concentration neglecting individual haemodynamic responses, no differences of power density in high frequency bands were detected. CONCLUSION: This method to define individual depth of anaesthesia as described, results in more consistent EEG patterns and may be useful in relating EEG to depth of anaesthesia.

Adult↗

PubMed1995

[EEG changes during sedation with gamma-hydroxybutyric acid].

Gamma-hydroxybutyric acid (GHB) is a naturally occurring transmitter in the mammalian brain, related to sleep regulation and possibly to energy balance in diving or hibernating animals. It has been used for almost 35 years as an intravenous agent for induction of anaesthesia and for long-term sedation. Its convincing pharmacological properties, without serious adverse effects on circulation or respiration, are compromised by its unpredictable duration of action. This is not a major problem with long-term sedation during ICU treatment. GHB has been used with good results for sedation of patients with severe brain injury, where it compares favourably with barbiturates. In animal studies, it seems to possess a protective action against hypoxia on a cellular and whole organ level. However, in some experimental animals GHB has been shown to produce seizure-like activities, and the compound is being used to produce absence-like seizures. GHB has been used in our ICU for years to provide adequate sedation for patients under controlled ventilation or for patients fighting the respirator during spontaneous respiration. No serious side effects were observed in these patients, while in some patients under haemodialysis hypernatraemia and metabolic alkalosis developed; both were reversible after discontinuation of GHB and restriction of additional sodium input (Somsanit, the commercially available GHB preparation in Germany, contains 9.2 mmol sodium/g; the daily dose averages 20-40 g GHB, i.e. 180-370 mmol sodium). PATIENTS AND METHODS. In 31 patients after major abdominal surgery, sedation was established with GHB 50 mg/kg BW injected via perfusion pump over a 20-min period. No centrally acting medication had been given for at least 2 h. A computer-based multichannel EEG system (CATEEM, MediSyst, Linden) was used, allowing for fast Fourier transformation, spectral analysis and topographical brain mapping. EEG during induction of sedation was followed after a baseline EEG (10 min) had been recorded. Patients receiving long-term sedation were studied daily for an additional 15-min period. Corresponding well to the clinical findings, EEG pattern changed to a slow delta-theta or delta-only rhythm within 10 min of the start of injection. Alpha and beta power decreased, while delta activity exhibited an increase. All changes were most obvious in frontal and central areas of the brain. In about one out of three patients, a burst--suppression pattern developed. Since automatic processing of EEG may fail to detect special patterns like the looked-for 3/s spikes and waves, the raw EEG was analysed visually by an expert neurologist. Both processed and conventionally analysed EEG were free of any seizure-like electrical activity. CONCLUSION. We conclude that animal data may not apply to the use of GHB in humans, provided the dose is limited to the clinical needs. GHB is used in clinical practice in doses twice as high, or even higher, than the one we use for induction, without obvious side effects. However, the suppression of theta rhythm we observed in about half of the patients studied may indicate that even less than 50 mg/kg BW might be sufficient for adequate sedation.

Abdomen↗

PubMed1995

A lower solubility recommends the use of desflurane more than isoflurane, halothane, and enflurane under low-flow conditions.

STUDY OBJECTIVE: To determine whether the lower solubility of desflurane, over that of isoflurane, enflurane, and halothane, favors its use in low-flow anesthesia. DESIGN: Prospective clinical study. SETTING: Technical University of Munich. PATIENTS: 40 elderly (> or = 65 yrs), ASA physical status II and III surgical patients. INTERVENTIONS: All patients were anesthetized and received delivered concentrations (FD) of 4% desflurane, 1.5% isoflurane, 1.8% enflurane, or 0.9% halothane (n = 10 patients for each anesthetic) in a fresh gas inflow of 3 L/min (high-flow), until end-tidal target concentrations (FA) of 2% desflurane, 0.5% isoflurane, 0.6% enflurane, and 0.3% halothane were obtained. After 30 minutes, the inflow was decreased to 1 L/min (low-flow), and the FD and the inspired concentration (FI) were adjusted to maintain the target concentration. MEASUREMENTS AND MAIN RESULTS: The concentrations of the halogenated anesthetics, as well as nitrous oxide, oxygen (O2), and carbon dioxide, were measured in delivered gas at the common gas outlet and at the endotracheal tube connector. Transcutaneous O2 saturation, noninvasive blood pressure, and heart rate were also measured. During the first 30 minutes of high-flow administration, the target concentration was attained sooner with desflurane than with isoflurane, enflurane, or halothane (median levels: 4 min vs. 6 min, 8 min, or 10 min; p < 0.01). After the reduction of inflow to 1 L/min, FD had to be materially increased to maintain F1 and FA for the more soluble anesthetics, but not for desflurane. CONCLUSIONS: At low flows, FD provides a reasonable surrogate of F1 and FA for desflurane, but not for isoflurane, enflurane, or halothane. The rapid and predictable titrability of desflurane favors its safe use in low-flow technique.

Aged↗

PubMed1995

[Anesthesia with low fresh gas flow in clinical routine use].

Anaesthesia in low-flow techniques gains increasing interest. The possibility of cost reduction, widespread use of highly developed anaesthesia machines and monitors, and introduction of two new fluorinated inhalational anaesthetics with low solubility in human tissues encourage the use of low-flow anaesthesia techniques. Further advantages are improved climatisation of breathing gas and estimation or even measurement of the important parameter "oxygen consumption". The anaesthesia machines and inhalational anaesthetics currently available allow a safe use of low-flow techniques if safety requirements are complied with (tight circle system, monitoring of: inspired oxygen concentration, minute ventilation, airway pressure, transcutaneous oxygen saturation). Low-flow anaesthesia techniques using a fresh gas flow rate of 1 l/min can be performed with almost every anaesthesia machine. However, the use of multigas monitors, analyzing most parts of the breathing gas, facilitates the use of low-flow techniques. Multigas monitors and anaesthesia machines equipped with intermittent fresh gas delivery are recommended for the use of fresh gas flow rates close to the metabolic rate. Because of its physicochemical properties the new inhalational anaesthetic desflurane offers advantages for the use in low-flow anaesthesia techniques.

Anesthesia, Closed-Circuit↗

PubMed1995

[Comparison of the effectiveness of orally administered clorazepate dipotassium and nordiazepam on preoperative anxiety].

Clorazepate dipotassium (Tranxilium) is one of the benzodiazepines which is widely used for oral premedication. After oral administration it is decarboxylated to its active metabolite nordiazepam (desmethyldiazepam). Nordiazepam is also commercially available in the form of drops (Tranxilium N). The aim of the present study was to compare the effect of these drugs on preoperative anxiety. One hundred and eight patients scheduled for orthopaedic surgery (ASA I-II) were studied. Medication was administered at 10 p.m. the evening before surgery (E) and at 7 a.m. on the morning of surgery (M). There were four groups: 1) E no medication; M clorazepate dipotassium; 2) E no medication; M nordiazepam; 3) E clorazepate dipotassium; M clorazepate dipotassium, 4) E clorazepate dipotassium; M nordiazepam. Dosages were: clorazepate dipotassium: body weight < 55 kg: 10 mg; body weight > 55 kg: 20 mg; nordiazepam: 1 gtt/kg; 5 mg = 24 gtt). Anxiety was measured by using the self-evaluating Erlangen anxiety scales, which measure both background and situational anxiety. Background anxiety (EAS-H) was evaluated during the evening before surgery; situational anxiety (EAS-S) was evaluated at the same time and also on the day of surgery before premedication and immediately before surgery. Pulse rate was measured each time the test was administered. There were no differences between the groups in sex, age, weight or the intervals between premedication and anaesthesia induction (p > 0.05). There were no statistically significant differences between the groups with respect to background anxiety. Situational anxiety did not significantly increase or decrease at any of the testing times, nor were there any differences between the groups (p > 0.05). Heart rate did not vary between the groups or with time (p > 0.05). In this group of patients undergoing elective orthopaedic procedures, clorazepate prevented a rise in anxiety in the immediate preoperative period. Since clorazepate is rapidly metabolized to nordiazepam when administered orally it might be predicted that the two drugs have similar properties. This hypothesis is confirmed by the results of the present study. We conclude that orally administered clorazepate dipotassium and nordiazepam have a similar effect on preoperative anxiety.

Administration, Oral↗

PubMed1994

[Hypervolemic hemodilution as a means of preventing homologous blood transfusion. A simple alternative to acute normovolemic hemodilution].

PROBLEM: Acute normovolenic hemodilution (ANH) is timeconsuming and complicated, and has only a small effect in reducing the need for homologous blood. A simpler procedure is hypervolemic hemodilution (HHD). In the present prospective, randomized study, HHD is compared with ANH for its blood-saving effect. STUDY DESIGN: Forty-nine patients undergoing total hip replacement were admitted. Group I (ANH): Withdrawal of 15 ml/kg bodyweight autologous blood and isovolemic replacement by hydroxyethyl starch (200/0.5). Group II (HHD): Infusion of 15 ml/kg bodyweight hydroxyethyl starch (200/0.5). RESULTS: No significant differences were found between the groups in terms of Hb, hematocrit and coagulation. The blood loss (intra-operative+drainage losses) was comparable in the two groups at 1274 +/- 310 ml (HHD) and 130 +/- 335 ml (ANH). During the period under investigation, 66% of the patients in the HHD group and 57% in the ANH group required no homologous blood. CONCLUSION: HHD is just as effective as ANH for reducing homologous blood requirements, and is much simpler to apply.

Blood Loss, Surgical↗

PubMed1994

[Strategies for minimizing homologous blood transfusion in elective interventions].

The risks associated with homologous blood transfusion necessitates the development of strategies for reducing the need for it. The most effective method is certainly preoperative donation of autologous blood, which leads to an increase in the absolute numbers of erythr789789 by the time surgery is performed. Depending on the type of preparation and storage, erythrocytes may be viable for between 49 days (liquid storage) and many years (deep frozen). By employing preoperative plasmapheresis, high-quality autologous fresh frozen plasma can be made available for use during surgery. Donation of autologous blood and plasmapheresis are preoperative measures that need to be organized. Another possibility is the use of a cell separator to recycle blood lost during surgery, and may be applied intra-operatively (aspiration from the surgical wound) or postoperative (drainage). Hemodilution has but little effect in reducing homologous blood requirements. Instead of the technically complex and time-consuming acute normovolemic hemodilution (ANH), the simpler hypervolemic alternative version (HHD) should be employed. Applying all the measures described above, an appreciable reduction in the need for homologous blood can be achieved. A prerequisite, however, is close cooperation between the surgeon an anaesthesiologist.

Blood Transfusion, Autologous↗

PubMed1994

[Drug administration via the endobronchial route. Possibilities of drug administration in emergency medicine].

For cardiopulmonary resuscitation, the endobronchial route represents a good means of administering drugs with a systemic effect, such as adrenaline and atropine, even without a venous line. Via this route, however, higher doses are needed (2.5 times as much as those normally given intravenously). In order to produce a larger surface area within the bronchio-alveolar space and thus speed up absorption, the drugs are diluted in 5-10 ml solvent (isotonic saline solution or distilled water). For endobronchial administration of a drug, various techniques are employed, for example, simply injecting it into the upper end of the (endotracheal) tube, puncture of the tube the use of an application probe introduced into the endobronchial tube, aspiration or venacaval catheter, or the EDGAR tube with an injection needle incorporated within the tube wall. After injection, the diluted medication is distributed into the tiny branches of the bronchial tree by repeated hyperventilation. Despite the need for an adequate alternative to the venous route in the field of cardiopulmonary resuscitation, we still have very few reliable facts about the endobronchial application technique.

Administration, Inhalation↗

PubMed1994

[Anesthesia with the closed PhysioFlex system in comparison with conventional anesthesia procedures].

So far the anaesthetic technique of the closed circuit system in clinical routine could not be used adequately, because suitable mixtures of respiration gas components were not available and the maintenance of a sufficient gas volume in the anaesthetic circle system was not possible with the standard anaesthesia machines. The anaesthesia machine PhysioFlex was especially constructed to deliver anaesthetics in a closed circuit system. In this anaesthesia machine the concentrations of the respiratory gases and the gas volume in the circle system are automatically controlled by a feedback mechanism. We compared the closed circuit system (CC group), with a high-flow system (HF group) and a low-flow system (LF group)--each system on 10 patients. It was noted that the respiratory gas concentrations were adjustable and held constant to a greater degree precise in the circuit system. After the induction the desired inspiratory oxygen-concentration was reached within 5 minutes, the expiratory isoflurane-concentration within 10 minutes in the CC group and was maintained reliable. The consumption of liquid isoflurane was 12.9 ml/h in the HF group, 7.5 ml/h in the LF group and 5.3 ml/h in the CC group. The anaesthetic management was possible without any problems in all three groups.

Adult↗

PubMed1992

[The determination of end-expiratory CO2 during resuscitation. Experience and results with the Normocap 200 (Fa. Datex) in preclinical resuscitation conditions].

Capnometers measure carbon dioxide (CO2) in inspired and expired air. Under physiological conditions end-tidal CO2 (peCO2) measurements closely reflect arterial pCO2 (paCO2). End-tidal CO2 concentration has been found to correlate with cardiac output in animal models and in clinical studies with cardiac arrest during cardiopulmonary resuscitation (CPR). In the present study in 23 cases of CPR end-tidal CO2 concentrations were registered during precordial compression with a transportable, battery-carried capnometer. In 7 cases of successful CPR mean concentrations of end-tidal CO2 were higher than in unsuccessful CPR (13 +/- 7 mmHg versus 8 +/- 6 mmHg). No statistical significance was found. In case of successful CPR there was a sudden rise in end-tidal CO2 up to 54 +/- 6 mmHg, indicating satisfactory spontaneous circulation. With capnometry it is possible to assess the efficacy of precordial compression during resuscitation and the return of spontaneous circulation in cardiopulmonary arrest.

Carbon Dioxide↗

PubMed1990

[A new tube for the endobronchial application of drugs].

During cardiopulmonary resuscitation, endobronchial administration of epinephrine, atropine and lidocaine is required as the initial step. This procedure provides a decisive time advantage, since it can be effected before venous access is established. The presently available techniques (direct application, catheter insertion, etc.), however, have disadvantages (interruption of ventilation, difficult catheter placement, time loss). For this reason we have developed a tube for endobronchial drug and gas application during resuscitation (EDGAR tube). It enables direct injection into the bronchial system via a separate injection canal within the wall of the tube that terminates at the tip of the tube. In this way, simple and safe application of the drugs to the appropriate absorption surface is ensured, without any loss of time. In view of these significant advantages, the use of the EDGAR tube is recommended for intubation for resuscitation purposes.

Atropine↗

PubMed1970

An irresponsible implantation.

Explore the source record for details and available documents.

Dental Implantation↗

PubMed1969

[Unjustifiable implantation].

Explore the source record for details and available documents.

Dental Implantation↗