Klaus Gerlach

Accuracy of point-of-care-testing (POCT) for determining hemoglobin concentrations.

Background: While point‐of‐care testing (POCT) is being used increasingly as a basis for deciding on perioperative erythrocyte transfusion, no valid standards currently exist concerning the accuracy of Hb concentration measurements. For clinical employment, however, the confidence limits (±2 SD) of these measurements should lie close to 5 g/l. The aim of the present study was to evaluate the accuracy and precision of point‐of‐care testing for blood hemoglobin concentration (cHb in g/l) measurements in critically ill patients.

Comparison of different airway management strategies to ventilate apneic, nonpreoxygenated patients.

ObjectiveEndotracheal intubation is the gold standard for providing emergency ventilation, but acquiring and maintaining intubation skills may be difficult. Recent reports indicate that even in urban emergency medical services with a high call volume, esophageal intubations were observed, requiring either perfect intubation skills or development of alternatives for emergency ventilation. DesignSimulated emergency ventilation in apneic patients employing four different airway devices that used small tidal volumes. SettingUniversity hospital operating room. SubjectsForty-eight ASA I/II patients who signed written informed consent before being enrolled into the study. InterventionsIn healthy adult patients without underlying respiratory or cardiac disease who were breathing room air before undergoing routine induction of surgery, 12 experienced professional paramedics inserted either a laryngeal mask airway (n = 12), Combitube (n = 12), or cuffed oropharyngeal airway (n = 12) or placed a face mask (n = 12) before providing ventilation with a pediatric (maximum volume, 700 mL) self-inflating bag with 100% oxygen for 3 mins. Measurements and Main ResultsIn three of 12 cuffed oropharyngeal airway patients, two of 12 laryngeal mask airway patients, and one of 12 Combitube patients, oxygen saturation fell below 90% during airway device insertion, and the experiment was terminated; no oxygenation failures occurred with the bag-valve-mask. Oxygen saturation decreased significantly (p < .05) during insertion of the Combitube and laryngeal mask but not with the bag-valve-mask and cuffed oropharyngeal airway; however, oxygen saturation increased after 1 min of ventilation with 100% oxygen. No differences in tidal lung volumes were observed between airway devices. ConclusionsParamedics were able to employ the laryngeal mask airway, Combitube, and cuffed oropharyngeal airway in apneic patients with normal lung compliance and airways. In this population, bag-valve-mask ventilation was the most simple and successful strategy. Small tidal volumes applied with a pediatric self-inflating bag and 100% oxygen resulted in adequate oxygenation and ventilation.

The Laryngeal Tube S: a modified simple airway device.

T he recently introduced single-lumen Laryngeal Tube can be inserted without additional equipment, and was proven in bench models (1,2) and preliminary clinical trials, to effectively ventilate and oxygenate patients with respiratory arrest (3,4) undergoing routine induction of anesthesia. Thus, the Laryngeal Tube may be used as an alternative airway device during either routine or emergency airway management. Handling of the Laryngeal Tube was later simplified by blocking two cuffs with one catheter instead of two. This procedure secures inflation of the oropharyngeal cuff first, and then of the esophageal cuff because of the different resistance characteristics of the connected tubing. Unfortunately, because of the design of the Laryngeal Tube, it may not be the best airway device for spontaneously breathing patients (5). As discussed earlier, a second disadvantage of the Laryngeal Tube may be the blind ending in the esophageal inlet, which may provoke esophageal rupture in the case of vomiting (3). Accordingly, the Laryngeal Tube was fitted with a second lumen serving for suctioning and free gastric drainage (Laryngeal Tube S [LTS]), but not for ventilation, as with the Combitube. In the present study, our purpose was to assess whether the LTS could provide sufficient ventilation and adequate oxygenation in patients undergoing routine induction of anesthesia for minor surgery. Methods

Discontinuous monitoring of propofol concentrations in expired alveolar gas and in arterial and venous plasma during artificial ventilation

Background: Analyzing propofol concentration in expired alveolar gas (cPA) may be considered as a convenient, noninvasive method to follow the propofol concentration in plasma (cPPL). In the current study, the authors established procedures to measure cPA and cPPL for the assessment of their relation in two animal models during anesthesia. Methods: Expired alveolar gas and mixed venous and arterial blood were simultaneously sampled during continuous application of propofol for general anesthesia to three goats and three pigs. Propofol infusion rates were varied to modify plasma concentrations. cPA, sampled cumulatively over several respiratory cycles, was quantified by thermal desorption gas chromatography–mass spectrometry. cPPL was determined using reversed phase high-performance liquid chromatography with fluorescence detection. Results: cPA ranged from 0 to 1.4 and from 0 to 22 parts per billion in goats and pigs, respectively, at cPPL of 0–8 &mgr;g/ml. The relation between cPA and cPPL was linear; however, the slopes of the regression lines varied between animals. Conclusion: Propofol can be quantified in expired alveolar gas. The results stress the role of marked species-specific variability.

Intubating laryngeal mask airway, laryngeal tube, 1100 ml self-inflating bag-alternatives for basic life support?

Insufficient oxygenation, ventilation and gastric inflation with subsequent regurgitation of stomach contents is a major hazard of bag-valve-face mask ventilation during the basic life support phase of cardiopulmonary resuscitation (CPR). The European Resuscitation Council has recommended smaller tidal volumes of approximately 500 ml as an effort to reduce gastric inflation; furthermore, the intubating laryngeal mask airway and the laryngeal tube have been recently developed in order to provide rapid ventilation and to secure the airway. The purpose of our study was to examine whether usage of a newly developed medium-size self-inflating bag (maximum volume, 1100 ml) in association with the intubating laryngeal mask airway, and laryngeal tube may provide adequate lung ventilation, while reducing the risk of gastric inflation in a bench model simulating the initial phase of CPR. Twenty house officers volunteered for our study. When using the laryngeal tube, and the intubating laryngeal mask airway, respectively, the medium-size (maximum volume, 1100 ml) versus adult (maximum volume, 1500 ml) self-inflating bag resulted in significantly (P<0.05) lower mean+/-S.E.M. lung tidal volumes (605+/-22 vs. 832+/-4 ml, and 666+/-27 vs. 887+/-37 ml, respectively), but comparable peak airway pressures. No gastric inflation occurred when using both devices with either ventilation bag. In conclusion, both the intubating laryngeal mask airway and laryngeal tube in combination with both an 1100 and 1500 ml maximum volume self inflating bag proved to be valid alternatives for emergency airway management in a bench model of a simulated unintubated cardiac arrest victim.

A new universal laryngoscope blade: a preliminary comparison with Macintosh laryngoscope blades

The Dörges universal laryngoscope blade has several features designed to facilitate tracheal intubation. The number of laryngoscope blades may be reduced from four to two, or even one, which indicate less space requirement and costs. This new universal laryngoscope blade, has a lower profile (height 15 vs. 22 mm) than a Macintosh laryngoscope blade size 3 and 4, which may facilitate manoeuvring of the laryngoscope in the mouth. In random order, 40 non-anaesthesia senior house officers used a Macintosh laryngoscope blade size 3 or 4 in an adult airway management trainer, a Macintosh laryngoscope blade size 2 in a paediatric airway management trainer, and the Dörges universal laryngoscope blade for both airway management trainers to perform orotracheal intubation. The number of intubation attempts and failures was counted. Participants reported the laryngoscopic view according to Cormack and Lehane. The time from touching the laryngoscope to the first adequate lung insufflation was measured, and subjective assessment regarding handling of both blades was recorded. Number of intubation failures, the laryngoscopic view according to Cormack and Lehane, and subjective assessment was comparable between groups. Orotracheal intubation of the adult airway management trainer with the Dörges universal laryngoscope blade took significantly less time compared to the Macintosh laryngoscope blades (14 (7-57) vs. 20 (8-43) s; P<0.001); all other intubating times were comparable. In conclusion, in this model, the Dörges universal laryngoscope blade was comparable to the Macintosh laryngoscope blades size 2-4, and may save time, cost and space.

The effect of midazolam on stress levels during simulated emergency medical service transport: a placebo-controlled, dose-response study.

Patients in the emergency medical service (EMS) may have increased endogenous catecholamines because of pain or fear and may benefit from sedation similar to premedication in the hospital. During a simulated EMS scene call, 72 healthy male volunteers were either transported by paramedics from a third-floor apartment through a staircase with subsequent EMS transport with sirens (three stress groups of n = 12; total, n = 36) or asked to sit on a chair for 5 min and lie down on a stretcher for 15 min (three control groups of n = 12; total, n = 36). Catecholamine plasma samples were measured in the respective stress and control groups at baseline and after placebo IV (n = 12) or 25 (n = 12) or 50 (n = 12) &mgr;g/kg of midazolam IV throughout the experiment, respectively. Statistical analysis was performed with analysis of variance;P < 0.05 was considered significant. The Placebo Stress versus Control group, but not the 50 &mgr;g/kg Stress Midazolam group, had both significantly increased epinephrine (73 ± 5 pg/mL versus 45 ± 5 pg/mL;P < 0.001) and norepinephrine (398 ± 34 pg/mL versus 278 ± 23 pg/mL;P < 0.01) plasma levels after staircase transport. After EMS transport, the Placebo Stress versus Control group had significantly increased epinephrine (51 ± 4 pg/mL versus 37 ± 4 pg/mL;P < 0.05) but not norepinephrine (216 ± 24 pg/mL versus 237 ± 18 pg/mL) plasma levels, whereas no significant differences in catecholamine plasma levels occurred between groups after either 25 or 50 &mgr;g/kg of midazolam. In conclusion, simulated EMS patients may be subject to more stress during staircase transport than during transport in an EMS vehicle. Titrating sedation with 25 &mgr;g/kg of midazolam significantly reduced endogenous catecholamines but not heart rate.

Emergency medical service transport-induced stress? An experimental approach with healthy volunteers

This randomized controlled trial was designed to evaluate the effects of simulated emergency medical service (EMS) transport related stress on hemodynamic variables, and catecholamine plasma levels. A total of 32 healthy male volunteers were randomized to being carried by paramedics from a third-floor apartment through a staircase with subsequent high-speed EMS transport with lights and sirens (stress; n = 16); or sitting on a chair for 5 min, and lying on a stretcher for 15 min (control; n = 16). Blood samples and hemodynamic variables were taken in the apartment before transfer, at the ground floor, and at the end of EMS transport in the stress group, and at corresponding time points in the control group. The stress versus control group had both significantly (P < 0.05) higher mean +/- SEM epinephrine (71 +/- 7 versus 37 +/- 3 pg/ml), and norepinephrine (397 +/- 29 versus 299 +/- 28 pg/ml) plasma levels after transport through the staircase. After EMS transport, the stress versus control group had significantly higher epinephrine (48 +/-6 versus 32 +/- 2 pg/ml), but not norepinephrine (214 +/- 20 versus 264 +/- 31 pg/ml) plasma levels. Heart rate increased significantly from 72 +/- 2 to 84 +/- 3 bpm after staircase transport, but not during and after EMS transport. In conclusion, volunteers being carried by paramedics through a staircase had a significant discharge of both epinephrine and norepinephrine resulting in increased heart rate, but only elevated epinephrine plasma levels during EMS transport. Transport through a staircase may reflect more stress than emergency EMS transport.

Effects of Opipramol as an Evening Anaesthesiologic Premedication

To date, opipramol has not been examined within the context of evening premedication in anaesthesiology. A suitable drug for such an application should induce anxiolytic and sleep-favouring effects. Due to its pharmacological properties, one would expect opipramol to lead to these effects. In order to test this possibility, 72 female patients were randomly assigned to 50 mg opipramol, 100 mg opipramol, or placebo (n = 24 patients per group) in the evening prior to surgery in a double-blind trial. Effects were recorded in the morning prior to the operation by means of self-rating questionnaires, regarding the patients’ current subjective state and their judgement of the quality of sleep during the night before. The self-rating was done by the Multidimensional Mood Inventory BSKE (EWL), by use of the Multidimensional Somatic Symptom List (MSKL), and by use of the Würzburg Sleep Questionnaire. Further dependent variables were heart rate and blood pressure. Opipramol significantly improved sleep quality. Especially the frequency of awakening at night was reduced. These effects could be observed predominantly after 100 mg opipramol. At this dosage, inner excitement was reduced as well. The autonomic variables remained uninfluenced. There were no adverse events and no hints for interactions with anaesthesiology.

Opipramol improves subjective quality of sleep the night prior to surgery: confirmatory testing of a double-blind, randomized clinical trial.

Objective: Due to its pharmacological properties, opipramol may be useful in the context of evening premedication in anaesthesiology. This trial examines whether quality of sleep the night prior to surgery can be improved by opipramol and whether this effect is dose dependent. A second objective of this study is to examine whether the emotional state (in particular anxiety) is affected by opipramol. Method: 72 female patients were randomly assigned to 100 mg opipramol, 150 mg opipramol or placebo (24 patients per group) in a double-blind trial. Drug application was in the evening prior to an elective surgery. Effects were recorded the next morning by means of self-rating questionnaires regarding subjective sleep quality of the last night and patients’ current subjective state. The self-rating was done by use of the Wuerzburg Sleep Questionnaire, by use of mood inventories [BSKE (EWL) and STAI-X1] and by use of the Multidimensional Somatic Symptom List. Further dependent variables were heart rate and blood pressure. Confirmatory data analysis was conducted for subjective quality of sleep. Results: 100 mg opipramol as well as 150 mg opipramol significantly improved subjective quality of sleep (p < 0.001). The drug conditions did not differ in this effect. Opipramol marginally reduced anxiety (STAI-X1). The autonomic variables remained uninfluenced. There were no adverse events and no hints for interaction with anaesthesia. Conclusion: Opipramol may be used as a premedication in the evening prior to surgery if the primary target is an impact on the experienced quality of sleep. For this a single dosage of 100 mg opipramol is sufficient and can be recommended.