Christoph Konrad

learning Manual Skills in Anesthesiology: Is There a Recommended Number of Cases for Anesthetic Procedures?

The learning process is a multidimensional function with a wide intra-and interindividual scattering. To determine the learning process in anesthesia, we evaluated 11 first-year residents according to their rate of success or failure when applying manual anesthesiological skills, such as performance of spinal, epidural, or brachial plexus anesthesia and tracheal intubation or insertion of an arterial line. Epidural anesthesia was the most difficult procedure (P < 0.05). Significant differences were found between epidural anesthesia and tracheal intubation (P < 0.05), insertion of an arterial line (P < 0.05), and brachial plexus block (P < 0.05), as well as between spinal anesthesia and orotracheal intubation (P < 0.05). Learning curves are a valid tool for monitoring institutional and individual success. Implications: To investigate the learning process in anesthesia, typical anesthetic procedures were performed by inexperienced residents during their first year. Learning curves were generated for each procedure performed. Epidural anesthesia was the most difficult procedure to perform (P < 0.05). (Anesth Analg 1998;86:635-9)

Continuous brachial plexus blockade in combination with the NMDA receptor antagonist memantine prevents phantom pain in acute traumatic upper limb amputees

Background: Hyperexcitability of N‐methyl‐d‐aspartate acid (NMDA) receptors may play an important role in the development of phantom limb pain (PLP).

In Vitro Effects of Different Medium Molecular Hydroxyethyl Starch Solutions and Lactated Ringer's Solution on Coagulation Using SONOCLOT

Hydroxyethyl starch (HES) solutions are widely used to replace intravascular volume. HES solutions differ from each other with regard to molecular weight and mode of hydroxyl substitution (degree of hydroxylation, C2:C6 hydroxyethyl ratio, concentration), factors which may have varying effects on coagulation. We studied, in vitro, three different HES preparations (molecular weight/degree of hydroxylation/concentration/C2:C6 ratio of substitution 70.000/0.5/6%/3.2; Pharmacia & Upjohn Co., Erlangen, Germany; 130.000/0.4/6%/11.2 and 200.000/0.5/6%/4.6; Fresenius Co., Bad Homburg, Germany) and, for comparison, lactated Ringer’s solution (RL) at 33% and 66% dilution with whole blood. The influence of hemodilution was measured by using routine laboratory variables and SONOCLOT (Sonoclot II Coagulation and Platelet Function Analyzer, Sienco Co.) analysis, using a viscoelastic test, on the cellular as well as on the plasmatic hemostatic system. For statistical analysis of quantitative data, we used nonparametric analysis of variance and adequate post hoc tests. Qualitative data were analyzed by using the nonparametric Kruskal-Wallis test. A P value below 0.05 was considered significant. In contrast to the control group with RL, the liquid phase of coagulation (activated clotting time) was slightly affected by the 33% diluted HES solutions. HES 70.000, 130.000, and 200.000 interfered significantly with the early stage of coagulation as expressed by the clot rate (gel/fibrin formation). Clot maturation and speed of maturation (time to peak) were strongly affected by HES 70.000 at all grades of dilution. HES 130.000 showed a faster clot formation process compared with the other HES solutions. HES 130.000 diluted 33% showed a better clot retraction as compared with the other HES solutions. In conclusion, in vitro hemodilution comparing different medium molecular weight HES solutions reveals that HES 130.000 seems preferable regarding some aspects of clot formation and retraction. RL affected clot formation only minimally, except for the early activation of clotting, which was measured by a shortened activated clotting time. Implications We investigated the effect of different hydroxyethyl starch (HES) solutions (70.000, 130.000, 200.000) on coagulation. Regarding clot formation and retraction, HES 130.000 had some advantages over the other tested HES solutions. Lactated Ringer’s solution affected coagulation only minimally, except for the early stage of clot formation.

The prevalence of latex sensitivity among anesthesiology staff

Reports dealing with allergic reactions to latex among health care professionals are increasing steadily.This study is the first epidemiological investigation of latex allergy among anesthesia staff. We tested 101 persons of the staff of the Institute of Anesthesiology, Kantonsspital, Lucerne, Switzerland, using a standardized questionnaire, prick test (latex extract), scratch test (latex glove), and immunoglobin E (IgE) analysis. Sixteen of 101 persons (15.8%) had a positive skin test. Two of them had a positive radioallergosorbent test (RAST) Class II, and one person was Class I. Risk factors were a history of atopy (P < 0.001) and positive skin tests on atopy screening (P = 0.016). IgE levels were increased in the latex-sensitive group. Three of the 11 sensitized persons (total sensitized persons 16) who performed spirometry had significantly reduced expiratory peak flow values during working hours. It is concluded that anesthesiology staff is at high risk of allergic sensitization to latex. The most important risk indicator was an atopy. Skin tests are more sensitive than blood tests (i.e., specific antibodies, IgE). (Anesth Analg 1997;84:629-33)

Generating a learning curve for pediatric caudal epidural blocks: an empirical evaluation of technical skills in novice and experienced anesthetists.

Background and Objectives Learning curves for anesthesia procedures in adult patients have been determined, but no data are available on procedures in pediatric anesthesia. The aim of this study was to assess the number of caudal blocks needed to guarantee a high success rate in performing caudal epidural analgesia in children. Methods At a teaching hospital, the technical skills of 7 residents in anesthesiology who performed caudal blocks were evaluated during 4 months using a standardized self-evaluation questionnaire. At the start of the study period, the residents had no prior experience in pediatric anesthesia or in performing caudal epidural blocks. All residents entered the pediatric rotation after a minimum of 1 year of training in adult general and regional anesthesia. The blocks were rated using a binary score. For comparison, the success rates of 8 experienced staff anesthesiologists were collected during the same period using the same self-evaluation questionnaire. Statistical analyses were performed by generating individual and institutional learning curves using the pooled data. The learning curves were calculated with the aid of a least-square fit model and 95% confidence intervals were estimated by a Monte Carlo procedure with a bootstrap technique. Results The success rate of residents was 80% after 32 procedures (95% confidence interval of 0.59 to 1.00). The pooled success rate of the staff anesthesiologists was 0.73 (mean) with a standard deviation of 0.45, which was not statistically different from the success rate of the residents. Conclusion High success rates in performing caudal anesthesia in pediatric patients can be acquired after a limited number of cases. Success rates of residents learning this procedure are comparable to the results of staff anesthesiologists.

The effects of in vitro hemodilution with gelatin, hydroxyethyl starch, and lactated Ringer's solution on markers of coagulation : An analysis using SONOCLOT

UNLABELLED Blood-saving strategies have recently been established to avoid allogeneic transfusion during surgery or after trauma. This includes an expanding use of crystalloids and colloids. These solutions interfere with coagulation systems, but quantitative measurements are still lacking. The SONOCLOT (Sienco Company, Morrison, CO) analysis (SCT), a viscoelastic test, measures clot formation and includes information on the cellular, as well as the plasmatic coagulation, system. To quantify hemodilutional effects on in vitro coagulation, we studied gelatin (G), hydroxyethyl starch 6% (HES; molecular weight 450,000), and lactated Ringers solution (RL) in 33% and 66% dilutions measuring routines laboratory and SCT variables. Hemodilution with RL tended to increase in vitro coagulability. Among the tested colloids, G had the least impact on markers of coagulation. G33% did not differ significantly from the undiluted control group. HES had the largest impact on markers of coagulation compared with G and RL. In conclusion, SCT provides a fast and easy to perform bedside test to quantify in vitro hemodilution. IMPLICATIONS The effects of progressive hemodilution on coagulation are difficult to measure. SONOCLOT analyses provide an easy to perform test with fast information on cellular and plasmatic coagulation properties. Among colloids, hydroxyethyl starch has the largest impact on markers of coagulation compared with gelatin or lactated Ringers solution.

Predominant CB2 receptor expression in endothelial cells of glioblastoma in humans.

BACKGROUND AND OBJECTIVES The most abundant malignant brain tumor in human is glioblastoma and patients with this type of tumor have a poor prognosis with high mortality. Glioblastoma are characterized particularly by fast growth and a dependence on blood vessel formation for survival. Cannabinoids (CBs) inhibit tumor growth by inducing apoptosis of tumor cells and impairing tumor angiogenesis. The distribution of CB1 and CB2 receptors in glioblastoma and associated endothelial vessels is still unknown. METHODS Tissue samples were collected consecutively after neurosurgery of 19 patients suspected glioblastoma and examined immunohistochemically for CB1 and CB2 receptor expression. Vessel endothelial cells of the sections were immunocytochemically identified by using a primary antibody against PECAM-1. Double labelling was performed for CB receptors and endothelial cells of the vessels by DAPI staining. RESULTS In endothelia of control tissue, about 24% and 45% of the cells were positive for CB1 and CB2 receptors. In glioblastoma endothelial cells, CB1 and CB2 receptors were present in about 38% and 54% of the cells respectively. In comparison to CB1, an elevated CB2 receptor expression was identified in glioblastoma. CONCLUSIONS The abundant expression and distribution of CB2 receptors in glioblastoma and particularly endothelial cells of glioblastoma indicate that impaired tumor growth in presence of CB may be associated with CB2 activation. Selective CB2 agonists might become important targets attenuating vascular endothelial growth factor (VEGF) signalling and thereby diminishing neoangiogenesis and glioblastoma growth.

Delta-9-THC based monotherapy in fibromyalgia patients on experimentally induced pain, axon reflex flare, and pain relief.

ABSTRACT Objective: Fibromyalgia (FM) is a chronic pain syndrome characterized by a distinct mechanical hyperalgesia and chronic pain. Recently, cannabinoids have been demonstrated as providing anti-nociceptive and anti-hyperalgesic effects in animal and human studies. Here, we explored in nine FM patients the efficacy of orally administered delta-9-tetrahydrocannabinol (THC) on electrically induced pain, axon reflex flare, and psychometric variables. Research design and methods: Patients received a daily dose of 2.5–15 mg of delta‐9-THC, with a weekly increase of 2.5 mg, as long as no side effects were reported. Psychometric variables were assessed each week by means of the West Haven-Yale Multidimensional Pain Inventory (MPI), Pittsburgh Sleep Quality Index (PSQI), Medical outcome survey-short form (MOS SF‐36), the Pain Disability Index (PDI), and the Fibromyalgia Impact Questionnaire (FIQ). In addition, patients recorded daily, in a diary, their overall pain intensity on a numeric scale. Each week, pain and axon reflex flare was evoked experimentally by administration of high intensity constant current pulses (1 Hz, pulse width 0.2 ms, current increase stepwise from 2.5–12.5 mA every 3 minutes) delivered via small surface electrodes, attached to the volar forearm skin. Main outcome measures: Daily pain recordings by the patient, experimentally induced pain, and axon reflex flare recorded by a laser Doppler scanner. Results: Five of nine FM patients withdrew during the study due to adverse side effects. Delta‐9-THC had no effect on the axon reflex flare, whereas electrically induced pain was significantly attenuated after doses of 10–15 mg delta‐9-THC ( p < 0.05). Daily-recorded pain of the FM patients was significantly reduced ( p < 0.01). Conclusions: This pilot study demonstrated that a generalized statement that delta‐9-THC is an analgetic drug cannot be made. However, a sub-population of FM patients reported significant benefit from the delta‐9-THC monotherapy. The unaffected electrically induced axon reflex flare, but decreased pain perception, suggests a central mode of action of the cannabinoid.

Blockade of the sciatic nerve in the popliteal fossa: a system for standardization in children.

The sciatic nerve can be blocked at different levels, providing excellent surgical and postoperative anesthesia and analgesia.We report a series of 50 blocks performed via the popliteal fossa in children. Localization of either the tibial or peroneal nerve was facilitated by a nerve stimulator. The local anesthetic solution was injected at the point where nerve stimulation was achieved with 0.4 mA at an impulse width of 1.0 ms. The depth of insertion of the stimulation cannula correlated with the age, weight, and height of the patients. The best predictor for depth of insertion was the patients weight. The minimal depth of insertion was 13 mm. No failure of blockade was seen in this case series. Blockade of the sciatic nerve can easily be performed in the popliteal fossa even in small children. Implications: Blockade of the sciatic nerve can easily be performed in the popliteal fossa even in small children. The depth of insertion of the stimulation cannula can best be estimated according to the weight of the patient. The minimal depth required was 13 mm. (Anesth Analg 1998;87:1256-8)

Transurethral resection syndrome: effect of the introduction into clinical practice of a new method for monitoring fluid absorption

STUDY OBJECTIVE To determine the effects of introduction of a new monitoring system for fluid absorption during transurethral resection of the prostate (TURP) using an irrigating solution containing 0.5% alcohol. STUDY DESIGN Prospective clinical investigation, with implementation of statistical process control. SETTING Inpatients for TURP at a major non-university teaching hospital. PATIENTS 312 male ASA physical status I, II, III, and IV patients scheduled for TURP. INTERVENTIONS Intraoperative breath alcohol levels were measured for detection of fluid absorption. MEASUREMENTS AND MAIN RESULTS Calculation of the amount of fluid absorbed using measured breath alcohol values. Process variability (i.e., numbers of patients with significant fluid absorption) was defined by statistical process control tools. No trend change of prevalence of fluid absorption was noted until 150 procedures had been completed. Reduction of prevalence of significant fluid absorption was noted and no patients were treated postoperatively in the intensive care unit. No relevant side effects were seen in patients with significant fluid absorption. No mortality and no severe clinical morbidity was seen after the introduction of the new monitoring. CONCLUSION Using an irrigating fluid marked with 0.5% ethanol resulted in a decreased prevalence of fluid absorption over time.