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.

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.

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 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.

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.

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.

[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.

[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.

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.

[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.

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.

[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.