The time required to perform different methods for endotracheal drug administration during CPR.

We compared the times necessary to perform different endotracheal drug application techniques during CPR. In a simulated CPR situation with a mannequin 28 paramedics and seven emergency physicians performed different drug instillation techniques in a randomized manner: direct injection into the upper end of the endotracheal tube (group tube), via a suction catheter placed into the bronchial system (group suction catheter), via a flexible venous catheter placed into the bronchial system (group venous catheter), using an EDGAR tube (an endotracheal tube with an injection channel within the wall of the tube (group EDGAR). We measured the time necessary to prepare the drug solution and compared the time necessary to prepare and perform each instillation method and the time the ventilation was interrupted. Comparison between groups was performed by the Kruskal-Wallis test. It took significantly longer to perform the more complicated techniques using suction catheters (26; 18 54 s) and venous catheters (30; 22-50 s) compared to the other two groups (median; min-max) (p < 0.05). No differences concerning the application time were found between the group tube (7; 5 14 s) and group EDGAR (8; 5-13 s). The time of interruption of chest compression's and ventilation: group suction tube (11; 5-19 s) and group catheter (12; 6-18 s) was significant longer than in group tube (5; 2-9 s) (p < 0.05). In group EDGAR the connection ventilator-tube remained intact due to its concept of drug application. The use of special devices such as suction catheters or venous catheters for endotracheal instillation during CPR results in significantly longer preparation and instillation times with a longer interruption of the oxygen supply and chest compression's.

Plasma epinephrine levels after epinephrine administration using different tracheal administration techniques in an adult CPR porcine model.

The aim of the study was to compare arterial plasma epinephrine levels after tracheal epinephrine application using three different tracheal instillation techniques at different tracheal levels in a porcine adult cardiopulmonary resuscitation model. In the prospective, randomized study, electrically-induced cardiopulmonary arrest was applied to 32 anaesthetized and paralyzed domestic pigs. After 3 min of cardiopulmonary arrest and 2 min of external chest compressions using a pneumatic compression device and mechanical ventilation, epinephrine was administered intravenously (20 microg/kg) or tracheally (50 microg/kg): using either direct injection into the upper end of the tracheal tube, via a catheter placed into the bronchial system and using a special tracheal application tube. In each group, there were eight pigs. Arterial blood samples were taken before and up to 10 min after epinephrine administration. Regression analysis was performed of the correlated data. The values of mean arterial blood pressure and end-tidal CO(2) during the time of observation did not differ between groups. Total plasma epinephrine concentrations showed a significant increase in all groups, but with no difference between the tracheal groups. However, peak epinephrine levels in the intravenous group were significantly higher than in tracheal groups. We conclude that administration using three different tracheal instillation levels result in similar onset and peak plasma epinephrine levels in this setting and therefore the preferred method of tracheal epinephrine application for cardiopulmonary resuscitation may be selected by other criteria.

Plasma catecholamine levels following tracheal and intravenous epinephrine administration in swine.

We compared plasma epinephrine levels after three different tracheal epinephrine application techniques and intravenous injection in male and female anesthetized and paralyzed domestic pigs. Epinephrine was administered intravenously (10 microg/kg) (group i.v.) or tracheally (100 microg/kg) either by direct injection into the upper end of the tracheal tube (group Tube), via a suction tube placed into the bronchial system (group Catheter) or using an EDGAR tube (group EDGAR), each group: n = 8. Arterial plasma samples were drawn before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7 and 10 min after epinephrine administration. Plasma concentrations of epinephrine were measured with high pressure liquid chromatography using electrochemical detection. Analysis was performed by regression analysis for correlated data. Total plasma epinephrine concentrations showed a significant increase within 0.5 min in all groups. However, peak plasma epinephrine levels in group i.v. were significantly higher than in tracheal groups, while no differences between tracheal groups over the time were found. We conclude that in swine with spontaneous circulation tracheal instillation techniques using special devices such as suction tubes or EDGAR tubes result in onset and peak plasma epinephrine levels equivalent to those after direct injection into the upper end of the tracheal tube.

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.

[Drug administration via the endobronchial route. Possibilities of drug administration in emergency medicine]. / Medikamentengabe über den endobronchialen Zugang. Möglichkeiten der Applikation in der Notfallmedizin.

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.

[Anesthesia with low fresh gas flow in clinical routine use]. / Anästhesie mit niedrigem Frischgasfluss in der klinischen Routine.

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.

[Comparison of the effectiveness of orally administered clorazepate dipotassium and nordiazepam on preoperative anxiety]. / Vergleich der Wirkung von oral appliziertem Dikaliumclorazepat und Nordiazepam auf die präoperative Angst.

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.

[Electroencephalographic demonstration of central nervous system effects of different premedication regimens]. / Elektroenzephalographische Darstellung der zentralen Auswirkungen verschiedener Prämedikationsregimes.

INTRODUCTION: For many years, the main goal of premedication was prevention of the dangerous side effects sometimes encountered in anesthetics with anticholinergics, antiemetic antihistaminics, and opioids. Because the rules were always preoperative fasting, premedication was administered i.m. Thus, the onset of action was within 15-30 min from administration. In recent years, with the introduction of newer anesthetics with fewer side effects, anxiolysis became the main aim in premedication. Moreover, the oral route became popular since it obviously did not increase the acidity or volume of the gastric content. However, the uptake and thus onset of action of orally administered drugs may take longer and can differ considerably between individual patients. Therefore, the optimum interval between administration and induction of anesthesia remains controversial. The present study was carried out to examine the time course of drug action and the effects of different premedication regimens on the electroencephalogram (EEG). PATIENTS AND METHODS: After obtaining informed consent, in 38 unselected adult patients (ASA I and II, < 65 years) scheduled for elective surgery, the EEG was recorded continuously before and after premedication. The patients were randomly assigned to four groups: M: midazolam, 0.2 mg/kg BW orally; N: nordazepam, 0.2 mg/kg BW orally; AP: atropine, 0.5 mg, plus promethazine, 50 mg i.m.; APP: atropine, 0.5 mg, plus promethazine, 50 mg, plus pethidine, 0.7 mg/kg BW i.m. The EEG was recorded for a reference period of 10 min before and a study period of 30 min after premedication. Automated EEG processing was performed with CATEEM (computer-aided topographical electroencephalometry). Surface electrodes were placed according to the 10-20 system. Date were collected via an amplifier (resistance 10 M omega) and a digitalization unit (filter 0.2-35 Hz, sampling rate 512 Hz, 12 bit A/D convertor). The original EEG signals were used in an interpolation algorythm to produce an additional 82 virtual recording points, allowing for high topographical resolution. After spectral analysis (fast Fourier transformation), the different frequency ranges of the EEG power spectrum are displayed in different colors. The screen displays the on-line map with color-based topographical power distribution. In order to achieve a pharmacodynamic time profile, the study period was subdivided into three periods of 10 min each. For clinical evaluation of vigilance, a 6-grade scoring system was used 1 = awake, 6 = not arousable). RESULTS: All data are presented with respect to reference period. The power density of each frequency range for each electrode is integrated over the selected period and mean values are shown. Changes in power density with time are expressed as percentage change from reference period. Biometrical data showed no significant differences between groups. The median vigilance score 30 min after premedication (end of study period) was 4 in groups M, AP, and APP, and 3 in group N. In both benzodiazepine groups, a distinct increase in power density was found in the beta-bands, while in groups AP and APP the increase was most pronounced in the delta and theta bands. In group M, there was a linear increase in beta 1 power up to 310%, while in the beta 2 range there was a 170% maximum within the second period of 10 min. In group N, there was a similar course with a lower increase in beta 1 (220%) and beta 2 (130%). Increases in both beta-bands were most pronounced with frontal electrodes. While group M showed an increase in delta power (150%), together with moderate suppression in alpha (alpha 1 50%, alpha 2 40%), nordazepam caused only a slight increase in delta (124%) and a distinct increase in alpha 2 to 150%, predominantly in the frontal areas. Group APP showed a linear increase in both delta up to 210% and theta power to 190%. (ABSTRACT TRUNCATED)

[Attempt at a definition of the individual anesthesia level by repetitive pain stimulation: correlation with EEG findings]. / Versuch einer Definition des individuellen Anästhesieniveaus über repetitive Schmerzreizung: Korrelation mit EEG-Befunden.

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.

[A new tube for the endobronchial application of drugs]. / Ein neuer Tubus zur endobronchialen Applikation von Medikamenten.

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.

[Hypervolemic hemodilution as a means of preventing homologous blood transfusion. A simple alternative to acute normovolemic hemodilution]. / Die hypervolämische Hämodilution als fremdblutsparende Massnahme. Eine einfache Alternative zur akuten normovolämischen Hämodilution.

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.

[Anesthesia with the closed PhysioFlex system in comparison with conventional anesthesia procedures]. / Anästhesie mit dem geschlossenen System PhysioFlex im Vergleich zu konventionellen Anästhesieverfahren.

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.

[Strategies for minimizing homologous blood transfusion in elective interventions]. / Strategien zur Minimierung der Fremdblutgabe bei elektiven Eingriffen.

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.

Intravenous clonidine decreases minimum end-tidal isoflurane for induction of electroencephalographic burst suppression.

The aim of this study was to determine the individual end-tidal isoflurane (ET ISO) threshold concentration for the induction of electroencephalographic (EEG) burst suppression with and without intravenous (I.V.) clonidine and to evaluate the EEG and cardiovascular response to skin incision during isoflurane/N2O anesthesia. Thirty-nine patients (ASA physical status I or II, 20-68 yr of age) undergoing orthopedic surgery were randomly assigned to receive I.V. saline (n = 20) or I.V. clonidine (3 microg/kg, n = 19). After detection of isoflurane-induced burst suppression, ET ISO was decreased in 0.1% ET steps until burst suppression diminished. Median minimum ET ISO for induction of burst suppression was 1.4% in the saline group and 0.9% in the clonidine group (P < 0.05). Before skin incision, EEG alpha 2 activity was significantly higher in the clonidine group compared with saline group. Fourteen patients (70%) in the saline group and 12 patients (63%) in the clonidine group showed a cardiovascular response to skin incision. After skin incision, EEG alpha 2 power was significantly decreased in both groups. A significant increase of delta activity was only found in the saline group. We conclude that the known minimum alveolar anesthetic concentration reduction of clonidine seems to be due to a direct cerebral action.

[The determination of end-expiratory CO2 during resuscitation. Experience and results with the Normocap 200 (Fa. Datex) in preclinical resuscitation conditions]. / Wertigkeit der endexspiratorischen CO2-Messung bei der Reanimation. Erfahrungen und Ergebnisse mit dem Normocap 200 (Fa. Datex) unter präklinischen Reanimationsbedingungen.

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.

[Comparison of the effect of desflurane and isoflurane on neuromuscular blockage with vecuronium on geriatric patients]. / Vergleich der Wirkung von Desfluran und Isofluran auf die neuromuskuläre Blockade mit Vecuronium bei geriatrischen Patienten.

Volatile anaesthetics have long been known to intensify the effect of muscle relaxants. In this study we investigated the effects of desflurane and isoflurane on the neuromuscular blockade of vecuronium in geriatric patients. Fifty-two patients requiring elective surgery, aged > or = 65 years, with ASA status II - III were randomly assigned to receive general anaesthesia using desflurane (Des, n = 26) or isoflurane (Iso, n = 26). The effects of both inhalation anaesthetics on the neuromuscular blockade of vecuronium were compared by means of the duration of the depression of the first twitch (T1) of a train-of-four stimulation pattern. Succinylcholine 1.5 mg/kg was used to facilitate intubation, vecuronium 0.05 mg/kg was given as the succinylcholine wore off; additional doses of 0.01 mg/kg were given when T1 exceeded 25% of baseline amplitude. There were no significant differences in the patients' biometric data or the duration of anaesthesia. The median duration of action of the first vecuronium dose (0.05 mg/kg) was: Des: 18.3 (9.4-42.9) min and Iso: 15.9 (3.1-46.0) min. The number of repetitive dosages (0.01 mg/kg) was: Des: 5; 0-13 and Iso: 5; 0-14 and their median duration was: Des: 10.2 (3.6-37.6) min and Iso: 8.9 (2.1-43.9) min. There were no differences between the two groups (p > 0.05). These results suggest that augmentation of neuromuscular blockade by older fluorinated anesthetics is also exhibited by desflurane. The magnitude of this effect in geriatric patients is similar to that of isoflurane.

[The use of propofol during diskectomy in neurosurgery]. / Zur Anwendung von Propofol bei Diskektomien in der Neurochirurgie.

The intravenous anaesthetic agent propofol has become more and more popular not only for induction but also for the maintenance of anaesthesia in all fields of surgery. For this purpose, different infusion rates and also combinations of propofol with opioids, nitrous oxide and volatile anaesthetic agents have been described. The present study was designed to find the best dosage regimen for short operations and rapid changes. The necessity for the frequently recommended standardized combination of propofol with opioids should be checked with respect to the cardiovascular effects. METHODS. A series of 60 patients (ASA I and II, age range 22-79 years) selected for discectomy were prospectively randomized to three groups. Half an hour before operation all patient received 0.5 mg atropine, 50 mg promethazine and 50 mg pethidine as i.m. premedication. In all groups anaesthesia was induced with propofol in a bolus dose of 2.5 mg/kg body weight over a period of approximately 45 s. After 5 mg atracurium the patients were intubated under 100 mg succinylcholine and normoventilated with 70% nitrous oxide and 30% oxygen. For relaxation 25 mg of atracurium were given. In group I propofol was administered in a dosage of 15 mg/kg body weight per hour for 10 min after induction. After this time the propofol infusion was reduced to 6 mg/kg body weight per hour. Group II received 0.1 mg fentanyl before induction. The dosage of propofol was similar to group I. In group III 0.1 mg of fentanyl was administered before induction and propofol was given with an infusion rate of 6 mg/kg body weight from the beginning. The following parameters were controlled and documented: systolic and diastolic blood pressure (SAP and DAP), heart rate (HF), end-expiratory carbon dioxide (eeCO2), inspiratory oxygen concentration (FiO2) and peripheral oxygen saturation (sO2). Recovery time was determined as the time from the end of the propofol infusion until eye-opening on command. RESULTS. In all groups anaesthesia could be induced and maintained without complications. There was a slight increase in SAP in group I after intubation, while in the groups with fentanyl a pronounced decrease of SAP was found simultaneously with induction of anaesthesia (Fig. 1). In group I HF showed significantly higher values after intubation and for the next 15 min than in group II and group III. A rapid and pronounced increase of end-tidal carbon dioxide occurred in the fentanyl groups with the beginning of spontaneous ventilation at the end of anaesthesia. There was a significantly longer recovery time in group II with fentanyl and initial higher propofol infusion rate. A correlation between dosage of propofol and recovery time could not be found. DISCUSSION. The results of this study demonstrate that a routine combination of propofol with opioids is not necessary even for painful surgical procedures if the propofol dosage is initially increased. There are differences in cardiovascular reactions between group I without and groups II and III with fentanyl, but in our patients these changes were of no clinical importance. An additional administration of fentanyl can prevent hypertensive reactions or tachycardia with intubation, but on the other hand fentanyl can also increase the cardial depression of propofol with a dangerous decrease in blood pressure and heart rate. Therefore in combination with opioids lower doses of propofol should be used for induction and maintenance of anaesthesia. If opioids are administered, signs of a residual postoperative respiratory depression have to be taken seriously.

Coagulation effects of a recently developed hydroxyethyl starch (HES 130/0.4) compared to hydroxyethyl starches with higher molecular weight.

BACKGROUND: Hydroxyethyl starches (HES) are known to interfere with blood coagulation according to molecular weight, the degree of substitution and the C2/C6 ratio. A recently developed low molecular hydroxyethyl starch (HES 130/0.4) was designed to reduce the blood compromising potency. METHODS: In this study, effects of a 30% in vitro haemodilution with the new HES preparation (HES 130/0.4) in comparison to HES 200/0.5, HES 450/0.7 and sodium chloride solution were investigated using intrinsic and extrinsic activated thrombelastography (TEG) and plasmatic coagulation tests. RESULTS: Whereas plasmatic tests revealed no prolongation of coagulation by HES in comparison to sodium chloride, the TEG variables clotting time, clot formation time and maximal clot firmness showed a significant (P<0.05) inhibition by all the HES preparations. The inhibition was most pronounced in HES 450 (P<0.05 vs HES 130) while HES 130 did not show a statistically significant difference in extrinsic activated maximal clot firmness when compared to sodium chloride. CONCLUSION: These in vitro results demonstrate that hydroxythyl starches especially compromise clot polymerisation. The new preparation HES 130/0.4 seems to inhibit platelet function to a lesser extent than hydroxyethyl starch preparations with a higher molecular weight and degree of substitution.

Experiences with the new inhalational agents in low-flow anesthesia and closed-circuit technique. Monitoring and technical equipment.

During recent years interest has focused on two completely fluorinated ethers, desflurane and sevoflurane, which promise a shorter induction of and emergence from anesthesia. Their physicochemical properties differ from isoflurane, enflurane and halothane, thus requiring new technical equipment and leading to a change in anesthesiological procedures. Low-flow anesthesia with desflurane can be performed, the technical equipment is available, especially vaporizers and gas analyzers. In contrast to anesthesia with isoflurane, enflurane and halothane, the initial high-flow wash-in period with desflurane can be shorter and the vaporizer setting can remain unchanged after fresh gas flow reduction. In order to administer desflurane and sevoflurane in closed circuit technique, new technical equipment is needed. Therefore, a computer controlled anesthesia machine was modified and the feedback mechanism to maintain the end-tidal anesthetic concentration was simulated. Isoflurane, desflurane or sevoflurane needed the same time for wash-in. Wash-out was slower with isoflurane; however, the technical equipment should be adapted to increase the elimination of the new agents. The consumption of desflurane and sevoflurane is effectively reduced by low-flow and closed circuit anesthesia.

Preoperative acute hypervolemic hemodilution with hydroxyethylstarch: an alternative to acute normovolemic hemodilution?

Acute normovolemic hemodilution (ANH) may help to reduce demand for homologous blood but requires extra time and apparatus. A more simple procedure is acute hypervolemic hemodilution (HHD), where hydroxyethylstarch is administered preoperatively without removal of blood. In a prospectively randomized study we compared ANH (preoperatively 15 mL/kg autologous blood removal and replacement with 15 mL/kg of hydroxyethylstarch with HHD (15 mL/kg of hydroxyethylstarch administered preoperatively) in 49 patients undergoing hip arthroplasty. To avoid excessive intravascular volume, we used the vasodilating effect of isoflurane. No significant differences were found between groups (ANH, n = 23; HHD, n = 26) for intraoperative blood loss (ANH versus HHD, median [minimum-maximum]); 545 [295-785] mL versus 520 [315-825] mL) and postoperative blood loss (730 [525-945] mL versus 780 [495-895] mL), postoperative hemoglobin, hemotocrit, platelet count or coagulation variables, and transfusion requirements (ANH 43% versus HHD 35% of patients received homologous blood) (P > 0.05). Heart rate did not change significantly in either group. In the ANH group mean arterial blood pressure (MAP) decreased after hemodilution (P < 0.05) while in the HHD group MAP did not change over time. Mean time required to perform ANH was 58 (46-62) min versus HHD 16 (12-19) min (P < 0.05). Costs for ANH were $63.60 USD and for HHD $32.75 USD (labor costs not included). In orthopedic patients undergoing hip replacement with a predicted blood loss of about 1000 mL, HHD seems to be a simple as well as time- and cost-saving alternative for ANH.