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.

Detection of fluid volume absorption by end-tidal alcohol monitoring in patients undergoing endoscopic renal pelvic surgery

STUDY OBJECTIVE

To determine the risk of relevant fluid absorption (calculated volume above 500 ml) during endoscopic procedures of the renal pelvis.

DESIGN

Prospective clinical investigation with implementation of statistical process control tools (SPC).

SETTING

Nonuniversity teaching hospital.

PATIENTS

62 consecutive ASA physical status I and II patients scheduled for endoscopic renal pelvic surgery with general anesthesia.

INTERVENTIONS

Intraoperative measurement of breath alcohol for detection of fluid absorption. Irrigation fluid (0.9% saline) with 1% alcohol for tracing the irrigation fluid.

MEASUREMENTS AND MAIN RESULTS

Calculation of the amount of fluid absorbed using breath alcohol values. Process variability (numbers of patients with relevant fluid absorption) defined by SPC. The prevalence of fluid absorption in endoscopic renal pelvic surgery was 6%. Peak fluid absorption during a vascular route was detected by the monitoring. Monitoring was easily introduced into routine clinical practice. No relevant side effects due to the monitoring were seen in patients with relevant fluid absorption. There was no mortality, but two patients with detected severe fluid overload were admitted to the intensive care unit for treatment.

CONCLUSION

Breath alcohol levels during general anesthesia for endoscopic renal pelvic surgery were technically simple to measure. Our results show the predictive value of alcohol monitoring, which has been previously demonstrated only for transurethral prostatectomy. The prevalence of relevant fluid absorption was 6% compared to 13% during transurethral resection of the prostate.

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

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 Ringer's 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 Ringer's solution.

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 patient's 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.

Comparing the enzyme allergosorbens and coated allergen particle tests for latex allergy: which in vitro test should be chosen by an anesthesiologist?

To determine sensitivity and specificity of the enzyme allergosorbens test (EAST) and the coated allergen particle Test (CAP) in detecting specific antibodies against latex, we compared these two methods in a previously investigated sample of an epidemiological study among our anesthesia staff. One hundred one blood samples were tested with EAST and CAP for specific antibodies against latex. Skin test results were used as references. CAP was more sensitive in detecting sensitized individuals than EAST (56% vs 18.8%). Two additional persons with previously negative skin tests were detected. These results suggest that the EAST system is not as sensitive as the CAP system. Therefore, the CAP system should be preferred for the in vitro diagnosis of latex allergy.

IMPLICATIONS

Testing for latex allergy requires time-consuming and technically difficult tests. Easy to perform in vitro tests for latex allergy are desirable. Our results indicate that the coated allergen particle test is more sensitive and easy to use than the enzyme allergosorbens test.

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.

[Insulin as an anabolic: hypoglycemia in the bodybuilding world]

Excessive body building may be dangerous. To promote athletic performance and to improve physical appearance many of the body builders abuse anabolic-androgenic steroids and other drugs. The abuse of insulin as an anabolic medication in this athletic community was followed by a case of severe hypoglycaemia in a body builder. A 30-year old male presented with cerebral symptoms of hypoglycaemia. Directly before an international competition he tried to stimulate muscle growth by using the hypoglycaemic stimulus to the growth hormone. To achieve this he injected 70 IE of a short-acting insulin subcutaneously, resulting in severe hypoglycaemia. After the initial administration of intravenous glucose by the paramedics, he lost consciousness and showed signs of convulsions. After orotracheal intubation by an emergency physician, despite of ongoing infusion of glucose the blood glucose concentration remained low as measured in the out-of-hospital setting. Finally administration of additional glucose and glucagon in the intensive care unit was able to stabilize the metabolic system. In any case of severe hypoglycaemia, repetitive measurements of blood glucose even in the prehospital setting should be performed to detect the hypoglycaemia especially if athletes are concerned.

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).

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).

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).

[Oxygen embolism after use of hydrogen peroxide in thoracic surgery]

Hydrogen peroxide is often used for irrigation of surgical wounds. In the presented two cases hydrogen peroxide was used to irrigate the thoracic cavity after thoracotomy for lung surgery. After irrigation with hydrogen peroxide only one patient showed clinical signs of pulmonary embolism. In both cases the postoperative recovery was uneventful. In one of the cases transesophageal echocardiography showed air bubbles, a sign of oxygen embolism, passing the right heart.

CONCLUSION

The application of hydrogen peroxide in preformed cavities, such as the thoracic, should be avoided.

Is an alkalinized lignocaine solution a better topical anaesthetic for intratracheal application?

Topical anaesthesia of the trachea is used to avoid coughing during emergence from anaesthesia. This study was designed to compare the effects of an alkalinized lignocaine and plain lignocaine solution given intratracheally. After institutional approval and written informed consent, 30 patients were randomized into three groups and received in a double-blind fashion: lignocaine, alkalinized lignocaine and normal saline for control. After application of normal or alkalinized lignocaine the tolerance to the tube was significantly better during extubation (P = 0.001). Noradrenaline levels were significantly diminished in the lignocaine groups (P < 0.05). Plain and alkalinized lignocaine solutions for topical anaesthesia significantly improved tolerance to the tracheal tube during emergence from anaesthesia. Plain and alkalinized lignocaine given directly before intubation reduced the sympathomimetic stress response resulting in a lower noradrenaline concentration and a reduced heart rate.

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).

[Risperidone after clozapine in therapy refractory schizoaffective psychosis--a case report]

Recently, American authors pronounced the hypothesis that Clozapine-response may be considered as a predictor of response to atypical neuroleptic. We report the history of a schizoaffektive patient unresponsive to butyrophenone and phenothiazine neuroleptic who was first treated with Clozapine and then with Risperidone and who reacted very differently to these atypical neuroleptic.

[Electronic expert system in medicine. For example ILIAD]

Expert systems are knowledge data bases founded on patient data, literature searches and opinions of experts. With these systems it is for instance possible to test or to take clinical decisions. ILIAD, USA version 4.2, an adaptable software using probabilistic strategies, was investigated. This system is, among other uses, employed for quality assurance and documentation, as a teaching instrument as well as a knowledge base. It comprises the ICD-9 index of diagnoses and a selected and commented up-to-date review of the literature from 'Mosby's Year Book of Medicine'. The features of ILIAD are presented, and the possibilities and limitations of its use as well as that of expert systems in general are discussed.

[Latex allergy--not only a threatening danger to patients. A case report from an anesthesiological department]

A 31-old male nurse of anesthesiology was exposed to rubber gloves over a period of ten years. An atopic diathesis was known. From time to time he had episodes of pollinosis. Since nine months he had suffered from conjunctivitis, rhinitis and shortness of breath while wearing latex gloves. During a night shift ten minutes after consumption of tropical fruit (bananas, kiwi) he had to care for a patient in the emergency room. He wore rubber gloves and had to clean the emergency room. Initially, his palms and feet itched. Then he experienced angor and increased perspiration 90 seconds later he suffered severe dyspnea and dysesthesia in the lower extremities. Treatment with theophylline and beta sympathomimetics, steroids and antihistaminics was successful. This male nurse had a positive history for contact urticaria after exposition to rubber. He suffered a dramatic exacerbation when wearing latex gloves and inhaling latex-contaminated air after eating tropical fruits. Fruit could have been a potent booster. Hospital employees with a history of atopic disease should be screened for potential latex allergy before occupational exposure.

Anti-CD3-enhanced interleukin-2 immunotherapy of pulmonary metastases

A newly developed monoclonal rat IgG 2b antibody which in vitro can activate both helper and cytolytic T-lymphocytes by binding to the CD3 epsilon subunit of the T-cell receptor complex was tested alone and in combination with Interleukin-2, a growth factor for activated T-cells, for ability to reduce established pulmonary metastases in a murine model. C57BL/6 mice injected iv with a tumor cell suspension of a weakly immunogenic fibrosarcoma, MCA106, were randomly assigned to 1 of 15 treatment groups for intraperitoneal injections with YCD3 (0, 0.1, 1, 10, or 100 micrograms) on Days 3, 5, 7, 10, 12, 17, and 19 or with IL-2 (0, 1000, or 50,000 units bid) on Days 3 through 7, 10 through 12, and 17 through 19. On Day 21 all mice were sacrificed for enumeration of metastases. Pooled splenocytes of three randomly selected mice from each group were assayed for surface expressions of T-cell markers Thy-1, Ly2, and L3T4.

RESULTS

High-dose IL-2 (50,000 units bid) in combination with low-dose YCD3 (1 microgram) reduced metastases 60% (P less than 0.005). YCD3 or IL-2 alone was ineffective. Combined high-dose IL-2 (50,000 units) and high-dose YCD3 (100 micrograms) resulted in 100% mortality. Phenotypically, YCD3 induced a dose-dependent depletion of T-cells from 25 to 2.4% (0.1 to 100 micrograms, respectively). These results suggest potential clinical applicability of low-dose anti-CD3 monoclonal antibody to enhance antitumor efficacy of high-dose IL-2. However, the toxicity of high-dose anti-CD3 and high-dose IL-2 cautions for care in selection of dose.

Tamoxifen potentiates in vivo antitumor activity of interleukin-2

Tamoxifen, an antiestrogen with efficacy in treatment of both estrogen receptor-positive and negative breast tumors, may be immunomodulatory. We tested tamoxifen's ability to augment the antitumor activity of interleukin-2 (IL-2), a lymphokine capable of expanding and activating lymphocytes, in the treatment of established pulmonary metastases of the weakly immunogenic murine fibrosarcoma MCA-106. Age-matched C57BL/6 female mice bearing pulmonary metastases induced by a tail vein injection of MCA-106 tumor suspension (5 x 10(5) cells/mouse) were treated from days 3 through 12 with intraperitoneal saline solution or IL-2 (50,000 units twice a day). Half of the mice in each group received plain and the remainder received tamoxifen-treated (2 units/ml) drinking water ad libitum for the duration of the experiment. All mice were killed on day 18 for enumeration of pulmonary metastases. Compared with saline-treated control mice, IL-2 and tamoxifen reduced metastases by 66% (p less than 0.0002) and 30% (p less than 0.005), respectively. IL-2 and tamoxifen combined reduced metastases 95% (p less than 0.0002), significantly better than did IL-2 (p less than 0.02) or tamoxifen (p less than 0.0003) alone. In vitro, tamoxifen inhibited proliferation of the weakly estrogen receptor-positive MCA-106 tumor by approximately 30%. Tamoxifen had no effect on the generation of 3-day IL-2-activated lymphocyte cytotoxicity against both natural killer-sensitive (YAC) and natural killer-resistant (MCA-106) target cells. Both YAC and MCA-106 tumor became more resistant to lysis with increased concentration of tamoxifen. This is the first demonstration of in vivo potentiation of IL-2 antitumor activity by tamoxifen and suggests its possible use clinically.

Solubilization of a mammalian beta-adrenergic receptor

Binding sites for iodohydroxybenzylpindolol with characteristics of a beta2-adrenergic receptor have been identified in a crude membrane fraction from guinea-pig lung. The binding sites could be solubilized by treatment of the membrane fraction with digitonin. Upon solubilization receptors retain their beta2-adrenergic type as indicated by the rank order of potencies of agonists in binding-inhibition experiments. The solubilized receptors demonstrate a marked increase in affinity for agonists compared with particulate receptors whereas antagonist affinity remains unchanged. Solubilized receptors are insensitive to divalent cations (Mg2+, Mn2+, Ca 2+) which increase the potency of agonists for particulate receptors. The effects of Mg2+ can be reversed by Gpp(NH)p in particulate preparations; Gpp(NH)p is ineffective for the solubilized preparation. These experiments establish that beta-adrenergic receptors can be solubilized even from crude mammalian membrane preparations. They also show that the mammalian beta-adrenergic receptor in situ is under constraints with respect to agonist affinity and is modulated by divalent cations and guanyl nucleotides in the intact membrane.

Beta-adrenergic receptors in guinea-pig myocardial tissue

Stereospecific binding sites for (-) [3H]-alprenolol, a beta-adrenergic antagonist, have been identified in guinea-pig myocardial broken cell preparations. The concentration of the sites was 0.3 pmoles per mg of protein and the dissociation constant (at 37 degrees C) 10(-8) M. A close correlation between the ability of various beta-adrenergic antagonists to compete with tracer alprenolol binding and to block the response of isoprenaline-stimulated myocardial adenylate cyclase has been found. Low affinity sites for the labelled beta-adrenergic antagonist in contrast to stereospecific sites are heat stable and do not discriminate between the (-) and the (+) forms of the beta-adrenergic antagonists. Adenylate cyclase in guinea-pig myocardial tissue is poorly stimulated by isoprenaline or 5'-guanylylimidodiphosphate. This is attributed to a high basal activity which could be lowered by a preincubation at 37 degrees C.