Ventilation with the esophageal-tracheal Combitube during general anaesthesia: assessing complications in 540 patients

Background

The esophageal-tracheal Combitube (ETC) was developed for the management of difficult airways but can also be used for general anaesthesia.

Methods

This clinical study collected data from patients undergoing anaesthesia with the ETC in order to assess the rate of complications.

Results

Five hundred forty patients were ventilated with the ETC. In 94.8% (512/540), insertion was performed for the first time by the respective physician. The following minor complications were observed: 38.7% sore throat, 30.9% blood on tube as sign of mucosal lesions and 17.0% cyanotic tongue. Experience decreased the risk of mucosal lesions (odds ratio [OR]: 2.3, 95% confidence interval [CI]: 1.5-3.5). A higher than recommended volume of the oropharyngeal cuff was associated with blood on the ETC (OR: 1.5, 95% CI: 1.0-2.3) and tongue cyanosis (OR: 2.3, 95% CI: 1.4-3.7). Ventilation for more than 2 h was associated with tongue cyanosis (OR: 2.2, 95% CI: 1.6-3.1) and tongue protrusion (OR: 1.4, 95% CI: 1.1-1.9).

Conclusion

We conclude that the Combitube may be used for short procedures requiring general anaesthesia, but the high rate of minor complications limits its value when other alternatives such as a laryngeal mask airway are available. The tested method appears safe regarding major complications, but minor complications are common. Adherence to recommended cuff volumes, experience with the ETC and limiting its use to surgeries lasting less than 2 h might reduce the rate of complications.

[Reconstruction of the examination of the laryngeal carcinoma of Emperor Frederick III by Rudolf Virchow]

Rudolf Virchow is one of the founders of modern pathology, and many of his ideas on inflammatory and neoplastic diseases are still valid today. Even for Virchow, determination of malignancy was not always easy. As an example, the laryngeal disease of Crown Prince Frederick William, the later Emperor Frederick III, is presented.The clinical findings at the beginning of the disease were suggestive of a carcinoma, though an inflammatory lesion was also discussed. Several attempts were made to remove the lesion bioptically, but local recurrences occurred and the first tissue samples were not examined histopathologically. Since laryngeal tumour operations had a high mortality at that time, histopathologic examinations were made in order to decide for or against an operation. The samples taken after pre-treatment did not meet Virchow's criteria for determining a carcinoma. Contrary to the present concept of a carcinoma in situ-carcinoma sequence, Virchow's concept was based on the assumption that carcinomas are not derived from the epithelium, but arise from a mesenchymal-epithelial transformation from the connective tissue. The clinical suspicion of a laryngeal carcinoma was confirmed only shortly before the patient's death and later by a post-mortem examination.The question repeatedly asked is whether Virchow should have diagnosed a carcinoma at the beginning of the disease. The answer has been the same for more than a hundred years: the clinician is dissatisfied with the histopathological diagnosis, so the pathologist is to blame.

Propofol, remifentanil and mivacurium: fast track surgery with poor intubating conditions

BACKGROUND

Mivacurium is widespread used because it is the non-depolarizing muscle relaxant with the shortest duration time. Therefore, it seems to be ideal for fast track or ambulatory surgery. However, especially in combination with propofol and remifentanil onset time remains unclear and incidence of poor intubating conditions seems to be higher than in other regimes of anesthesia.

METHODS

We included 35 ear, nose and throat (ENT) patients in this study. Muscle relaxation was measured by acceleromyograhpy at the adductor pollicis muscle (a.p.m.) and intubating conditions were evaluated. Anesthesia was induced with 2.5 mg kg-1 propofol and 1 µg kg-1 remifentanil and intubation was performed three minutes after the administration of 0.2 mg kg-1 mivacurium. Open vocal cords conjoined with full relaxation of the a.p.m., easy mouth opening and prevention of coughing and bucking represented the primary endpoint in this study.

RESULTS

Only 20% of patients (N.=7) had optimal intubating conditions and achieved the primary endpoint. In 21 patients (60%) a complete block of the a.p.m. could not be achieved and in six patients (17%) the vocal cords were closed. In seven patients (20%) we observed difficult mouth opening and in 11 patients (31%) coughing and bucking. In addition, we found a prolonged onset time of 228±95 seconds (mean±SD).

CONCLUSION

In combination with propofol and remifentanil the muscle relaxant agent mivacurium led to uncertain muscle relaxation and to poor intubating conditions. Therefore the study was aborted after 35 patients. Probably mivacurium is not a useful muscle relaxant agent if fast and deep muscle relaxation is needed. The advantage of a short duration time is foiled by intubation complications due to insufficient muscle relaxation.

Ethanol-induced malfunction of neutrophils respiratory burst on patients suffering from alcohol dependence

BACKGROUND

Polymorphonuclear, neutrophil granulocytes (PMN) play a major role in the control of infections, and people who abuse alcohol are susceptible to infections. Resistance against infections ensues intracellularly following initial phagocytosis of microorganisms with the oxygen-dependent respiratory burst, the key enzyme of which is the respiratory burst oxidase, whereby oxygen radicals are produced for microbial destruction. To date there is insufficient information available in connection with the process of impaired defence against infection in patients suffering from alcohol dependence. Therefore, our investigation was carried out to determine the influence of alcohol exposition on the formation of oxygen radicals and the respiratory burst.

METHODS

4.5 ml of whole blood was taken from 10 healthy adults and 10 patients suffering from alcohol dependence. An additional 3.5 ml of whole blood was taken from the alcoholic patients for determination of the blood alcohol concentration. The respiratory burst of PMN was tested using the Four-Colour-Continuous Flow Cytometer. Each experimental procedure consisted of 4 test samples [negative controls, Escherichia coli, FMLP-supplement (N-formyl-l-methionyl-l-leucyl-l-phenylalanin), PMA-supplement (phorbol-12-myristate-13-acetate)]. Differing concentrations of ethanol were also introduced to each of the tests performed (0.20 to 4.00 g/l).

RESULTS

Ethanol revealed a marked decrease of burst activity in those patients suffering from alcoholism with increased alcohol concentration. A dependence between the burst activity and the ethanol concentration was seen to be statistically significant. This effect was only evident after stimulation with E. coli and FMLP in those patients with alcohol dependence.

CONCLUSION

The results presented in this study show an impairment in the function of PMN in those patients addicted to alcohol due to the decrease in burst activity. In view of the results of the different stimuli, the second-messenger effects were not evident. A clarification of this phenomenon could well be assumed as an allosteric receptor effect on the burst oxidase, namely, a direct effect on the phagocytosis interaction between circulating granulocytes and causative organisms.

Effect of ethanol on cardiac single sodium channel gating

Alcohol in modest and higher doses has the potential to induce cardiac arrhythmias. The most famous alcohol-related arrhythmia is the "holiday heart syndrome". Furthermore, there is a clear association between excessive alcohol consumption and the risk of sudden cardiac death. However, the acute effects of ethanol on arrhythmia induction are not well understood. The effect of ethanol on single cardiac sodium channels has not been studied yet. To elucidate the effect of ethanol on human cardiac sodium channels we performed a patch clamp study in HEK-293 cells overexpressing the human cardiac sodium channel. We used HEK-293 cells overexpressing the human cardiac sodium channel (Na(1.5)). Single channel gating was investigated by the cell-attached patch clamp technique. Sodium channel currents were elicited by depolarizing pulses from -120 to -20mV for a duration of 150ms. Single channel availability, open probability and peak average current were assessed baseline and after addition of ethanol in increasing concentrations (0.50 per thousand (10.9mM), 1.00 per thousand (21.7mM), 2.00 per thousand (43.5mM) and 4.00 per thousand (87.0mM)). We found a concentration-dependent reduction of open probability which was statistically significant at 2.00 per thousand ethanol (66.5+/-14% of control). At higher concentrations (4.00 per thousand) also availability decreased to 66.5+/-11.0% of control. This resulted in a significant decrease of peak average current at 2.00 per thousand and at 4.00 per thousand ethanol (61.8+/-7.4 and 53.0+/-8.2% of control). For the first time the present study demonstrates acute inhibitory effects of ethanol on single cardiac sodium channel gating and provides one potential mechanism for the well known clinical observation that ethanol triggers supraventricular and ventricular arrhythmias.

Combination of repeated single-session percutaneous ethanol injection and transarterial chemoembolisation compared to repeated single-session percutaneous ethanol injection in patients with non-resectable hepatocellular carcinoma

AIM: To evaluate the treatment effect of percutaneous ethanol injection (PEI) for patients with advanced, non-resectable HCC compared with combination of transarterial chemoembolisation (TACE) and repeated single-session PEI, repeated single-session PEI alone, repeated TACE alone, or best supportive care.

METHODS: All patients who received PEI treatment during the study period were included and stratified to one of the following treatment modalities according to physical status and tumor extent: combination of TACE and repeated single-session PEI, repeated single-session PEI alone, repeated TACE alone, or best supportive care. Prognostic value of clinical parameters including Okuda-classification, presence of portal vein thrombosis, presence of ascites, number of tumors, maximum tumor diameter, and serum cholinesterase (CHE), as well as Child-Pugh stage, α-fetoprotein (AFP), fever, incidence of complications were assessed and compared between the groups. Survival was determined using Kaplan-Meier and multivariate regression analyses.

RESULTS: The 1- and 3-year survival of all patients was 73% and 47%. In the subgroup analyses, the combination of TACE and PEI (1) was associated with a longer survival (1-, 3-, 5-year survival: 90%, 52%, and 43%) compared to PEI treatment alone (2) (1-, 3-, 5-year survival: 65%, 50%, and 37%). Secondary PEI after initial stratification to TACE (3) yielded comparable results (1-, 3-, 5-year survival: 91%, 40%, and 30%) while PEI after stratification to best supportive care (4) was associated with decreased survival (1-, 3-, 5-year survival: 50%, 23%, 12%). Apart from the chosen treatment modalities, predictors for better survival were tumor number (n < 5), tumor size (< 5 cm), no ascites before PEI, and stable serum cholinesterase after PEI (P < 0.05). The mortality within 2 wk after PEI was 2.8% (n = 3). There were 24 (8.9%) major complications after PEI including segmental liver infarction, focal liver necrosis, and liver abscess. All complications could be managed non-surgically.

CONCLUSION: Repeated single-session PEI is effective in patients with advanced HCC at an acceptable and manageable complication rate. Patients stratified to a combination of TACE and PEI can expect longer survival than those stratified to repeated PEI alone. Furthermore, patients with large or multiple tumors in good clinical status may also profit from a combination of TACE and reconsideration for secondary PEI.

The carina as a landmark for central venous catheter placement in small children

Central venous devices are frequently used in children to monitor haemodynamic status, to administer fluids, medication, parenteral nutrition and for blood sampling. Life-threatening complications that may occur on insertion if the central venous catheter (CVC) is misplaced, are cardiac tamponade or a hydro-/haemopericardium. There is still controversy over the optimum catheter tip position in paediatric patients, whether to place the CVC tip in the superior vena cava, outside the pericardial boundaries or in the right atrium. However, the exact location of the pericardium cannot be seen on a normal chest x-ray. The carina is a radiographic marker for CVC placement, suggested on the basis of studies with conserved and fresh adult cadavers. In order to confirm this landmark for children, the present study was performed with 31 fresh cadavers of small children (mean age 12.5+/-3.4 months) that had been selected for autopsy in the Institute of Legal Medicine. Results clearly demonstrate that the carina was 0.5+/-0.04 cm above the pericardial duplication as it transversed the SVC. In no infant cadaver was the carina inferior to the pericardium. Thus, the results are analogous to those in adults and confirm that the carina is a simple anatomical-radiological landmark, superior to the pericardial reflection, that can be used to identify the placement of CVC even in newborn and small children.

The lingual tonsillar hyperplasia in relation to unanticipated difficult intubation: is there any relationship between lingual tonsillar hyperplasia and tonsillectomy?

The lingual tonsillar hyperplasia (LTH) is a rare and dangerous condition of the upper airway because it is one of several risks during intubation which can cause serious complications like cardiac arrest, cerebral anoxia, and death. The LTH is rarely detectable during a routine oropharyngeal examination. The lingual tonsil is of particular interest to forensic medicine to assess cases with malpractice in connection with intubation difficulties. Our study looked at how often autopsy specimens had enlarged lingual tonsils and whether any relationship existed between LTH and tonsillectomies. In total, 497 corpses were examined. Only in 16 cases (3.2%), an enlarged lingual tonsil was detected. Of the 16 cases, 10 (62.5%) had normal palatine tonsils; the other 6 cases (37.5%) had no palatine tonsils or were scarred, atrophied, or only remnants remained. Statistically, it was not possible to prove any relationship between enlarged lingual tonsils and tonsillectomies. From the forensic point of view, a description of the lingual tonsil should appear in special cases in autopsy reports. When reviewing malpractice cases, special anatomic features should be described.

Repeatability of measurements of the initial distribution volume of glucose in haemodynamically stable patients

AIMS

The initial distribution volume of glucose (IDVG) has been proposed to provide a useful tool to estimate the central extracellular fluid volume. The purpose of this study was to determine the repetition interval of two consecutive measurements in haemodynamically stable patients without presence of recent changes in fluid status.

METHODS

Twenty-nine patients admitted to the general intensive care unit of the University of Hirosaki Hospital were entered into this study. After achieving a haemodynamically stable state in each patient regardless of an infusion of vasoactive drugs, two glucose challenges at an interval of either 30 or 60 min, were carried out to calculate the IDVG. The IDVG was calculated using a one-compartment model after intravenous administration of glucose (5 g) followed by serial arterial blood sampling.

RESULTS

Although plasma glucose levels immediately before the second glucose challenge in either group were increased compared with those of the first challenge (P < 0.001, respectively), the bias of the IDVG measurements was 0.08 +/- 0.32 L (SD) for the 30-min group and -0.19 +/- 0.28 L for the 60-min group.

CONCLUSIONS

Our results indicate that IDVG determinations can be reliably repeated within a minimum interval of 30 min.

Das EasyScope - Eine Alternative zum bewährten Macintosh-Laryngoskop?

OBJECTIVE

This study was conducted to compare two different techniques used for tracheal intubation (TI). We evaluated airway management conditions for a conventional Macintosh laryngoscope and the Brummert EasyScope, a new device.

METHODS

A prospective trial was conducted with 20 medical students who had no prior airway management experience. Intubation was performed on an Ambu manikin. Following didactic instruction, each participant took turns performing TI using the Macintosh and EasyScope devices under direct supervision. Time required for TI, the number of attempts, and the number of times teeth were contacted were documented for each device. All participants also completed a questionnaire to determine self-assessed comfort and skill level for both the Macintosh and EasyScope devices.

RESULTS

Time required for TI was comparable for both devices, although a trend toward slightly lower times for the EasyScope was observed. There was a lower rate of tooth contact during laryngoscopy and a lower rate of unsuccessful intubation attempts while using the EasyScope. Furthermore, the students felt the EasyScope was subjectively easier to use and required less effort during TI when compared with the Macintosh laryngoscope.

CONCLUSION

Personnel not accustomed to a particular airway management technique achieved comparable outcomes when using either the Macintosh laryngoscope or the EasyScope device for TI. Possible reduction of effort required for tracheal intubation or better dental protection have to be evaluated for the EasyScope in further clinical studies.

Koniotomieübungen an der Leiche - Erfahrungen in der Ausbildung mit Medizinstudenten, Anästhesisten und Notärzten

OBJECTIVE

Should the technique of surgical cricothyroidotomy be practiced on cadavers and should it be a compulsory part of the teaching curriculum? Is it wise to use a speculum for the insertion of the endotracheal tube? What is the optimum size of the tube?

METHODS

A surgical cricothyroidotomy with a speculum was carried out on 30 cadavers from the Institute of Legal Medicine, Medical School Hannover. This took place as part of a official and voluntary course for students of advanced semesters, anaesthetists and emergency doctors with the subjects "cricothyroidotomy, chest drainage and venous cut-down". The surgical cricothyroidotomy without the use of a speculum was carried out on 5 cadavers by two clinicians well practiced in this technique. The elapsed time between skin incision and the insertion of the endotracheal tube was measured on all five subjects. After the course the participants were asked if they were able to carry out a cricothyroidotomy in an emergency. They were also asked whether this course should be a compulsory part of their curriculum and whether practical sessions should take place. During autopsies at the Institute of Legal Medicine the length of the ligamentum conicum was measured on 40 corpses with reclined and non-reclined heads.

RESULTS

The average time of storage of the cadavers was 4.2 days +/- 1.9 days. The cricothyroidotomy was possible on all 35 cadavers. In one case (3,3 %) the result was a complete rupture of the cricoid cartilage. In 5 cases (16.7 %) the horizontal incision was torn due to prising with the speculum. Difficult situations always occured when the skin incision was not exactly in the midline. The average time to place the endotracheal tube into the trachea by the surgical procedure of cricothyroidotomy was 22.4 seconds +/- 3.1 seconds (minimum 18 seconds, maximum 26 seconds). 10 % of the medical students and 50 % of the anaesthetists and emergency doctors felt they would be prepared to carry out a cricothyroidotomy in an emergency. 90 % of the students and respectively 80 % of the anaesthetists and emergency doctors stated that they would like to practice the technique on a cadaver again. Almost all participants were of the opinion that the course should be integrated as a compulsory course in a future educational curriculum. The average distance between the thyroid cartilage and the cricoid cartilage was 9.5 mm +/- 1.9 mm with non-reclined head (minimum 6 mm, maximum 14 mm) and 11.9 mm +/- 2.5 mm with reclined head (minimum 7 mm, maximum 18 mm). The average difference of distances was 2.4 mm +/- 1.2 mm (minimum 1 mm, maximum 6 mm) in reclined and non-reclined heads.

CONCLUSIONS

In our opinion it is highly recommended that the technique of cricothyroidotomy should be practiced on cadavers and that the course should become a compulsory part in a future educational curriculum. In addition the incision of the ligamentum conicum using dilators or a speculum is not to be recommended from the point of view of this study. The tracheal tube used in this study (reinforced wire tube, ID 6.0) was best suited for surgical cricothyroidotomy.

Applied anatomy of the superior vena cava—the carina as a landmark to guide central venous catheter placement

BACKGROUND

Cardiac tamponade is a serious complication of central venous catheter (CVC) insertion. Current guidelines strongly advise that the CVC tip should be located in the superior vena cava (SVC) and outside the pericardial sac. This may be difficult to verify as the exact location of the pericardium cannot be seen on a normal chest x-ray. The carina is an alternative radiographic marker for correct CVC placement, suggested on the basis of studies of embalmed cadavers.

METHODS

We set out to confirm this radiographic landmark in 39 fresh cadavers (age 58.4 (3.4) (mean and SE) yr) and to compare the results with those from ethanol-formalin-fixed cadavers.

RESULTS

We found that the carina was 0.8 (0.05) cm above the pericardial sac as it transverses the SVC. In no case was the carina inferior to the pericardial reflection and our study confirmed the previous findings. All the measured distances were significantly greater in fresh cadavers.

CONCLUSIONS

We confirm that the carina is a reliable, simple anatomical landmark that can be identified in vivo for the correct placement of CVCs outside the boundaries of the pericardial sac.

Evaluation of endoscopic retrograde cholangiopancreatography under conscious sedation and general anesthesia

BACKGROUND AND STUDY AIMS

In adults, general anesthesia is usually only provided during endoscopic retrograde cholangiopancreatography (ERCP) when prior attempts using conscious sedation have failed. It was hypothesized that in our hospital, other factors might be associated with general anesthesia for ERCP. The aim of this study was therefore to assess the indications for ERCP under general anesthesia, and to evaluate the underlying diseases, type, and efficacy of ERCP under general anesthesia in comparison with conscious sedation.

PATIENTS AND METHODS

We retrospectively analyzed 1,056 ERCPs that had been carried out with the patients under general anesthesia or conscious sedation. The indications for general anesthesia were recorded, and the underlying diseases, the type and success of the interventions, and the causes of premature ERCP termination in both groups were assessed.

RESULTS

Eighteen percent of the ERCPs were performed under general anesthesia and 82% under conscious sedation. The indications for general anesthesia were related to the type of procedure planned (46%), premature termination of ERCP under conscious sedation (28%), and other reasons. Patients with primary sclerosing cholangitis and liver transplant recipients received general anesthesia more frequently (general anesthesia vs. conscious sedation, 36% vs. 16%, P < 0.0001 and 22% vs. 13%, P = 0.003). Conscious sedation was provided more frequently in patients with neoplasms and cholelithiasis (21% vs. 12%, P = 0.004 and 13% vs. 3%, P < 0.001). Painful dilations were performed more frequently with the patients under general anesthesia (60% vs. 19%, P < 0.001), whereas major papillotomies were preferably performed with conscious sedation (34% vs. 21%, P = 0.006). More interventions per ERCP were performed with the patient under general anesthesia compared to conscious sedation (P < 0.001), during the same time (51 +/- 28 min vs. 52 +/- 26 min, P = 0.39). With conscious sedation, the ERCP failure rate was double that with general anesthesia (7% vs. 14%, P = 0.012), mainly due to inadequate conscious sedation (61%).

CONCLUSIONS

The frequent use of general anesthesia for ERCP at our institution is related to the underlying diseases, which are frequently treated with complex and painful ERCP procedures. The efficacy of ERCP with general anesthesia supports a continued preference for general anesthesia rather than conscious sedation when complex and painful interventional ERCP procedures are planned.

Multicenter experiences with a single lead electrode for dual chamber ICD systems

Monitoring of atrial signals improves the accuracy in identifying supraventricular tachyarrhythmias to prevent inappropriate therapies in patients with implantable ICDs. Since difficulties due to the additional atrial lead were found in dual chamber ICD systems with two leads, the authors designed a single pass VDD lead for use with dual chamber ICDs. After a successful animal study, the prototype VDD lead (single coil defibrillation lead with two additional fractally coated rings for bipolar sensing in the atrium) was temporarily used in 30 patients during a German multicenter study. Atrial and ventricular signals were recorded during sinus rhythm (SR), atrial flutter, AF, and VT or VF. The implantation of the lead was successful in 27 of 30 patients. Mean atrial pacing threshold was 2.5 +/- 0.9 V/0.5 ms, mean atrial impedance was 213 +/- 31 ohms. Atrial amplitudes were greater during SR (2.7 +/- 1.6 mV) than during atrial flutter (1.46 +/- 0.3 mV, P < 0.05) or AF (0.93 +/- 0.37 mV, P < 0.01). During VF atrial "sinus" signals had significantly (P < 0.01) lower amplitudes (1.4 +/- 0.52 mV) than during SR. The mean ventricular sensing was 13.3 +/- 7.9 mV and mean ventricular impedance was 577 +/- 64 ohms. Defibrillation was successful with a 20-J shock in all patients. In addition, 99.6% of P waves could be detected in SR and 84.4% of flutter waves during atrial flutter. During AF, 56.6% of atrial signals could be detected without modification of the signal amplifier. In conclusion, a new designed VDD dual chamber lead provides stable detection of atrial and ventricular signals during SR and atrial flutter. Reliable detection of atrial signals is possible without modification of the ICD amplifier.

Identification of an autoimmune serum containing antibodies against the Barr body

Transcriptional inactivation of one X chromosome in mammalian female somatic cells leads to condensation of the inactive X chromosome into the heterochromatic sex chromatin, or Barr body. Little is known about the molecular composition and structure of the Barr body or the mechanisms leading to its formation in female nuclei. Because human sera from patients with autoimmune diseases often contain antibodies against a variety of cellular components, we reasoned that some autoimmune sera may contain antibodies against proteins associated with the Barr body. Therefore, we screened autoimmune sera by immunofluorescence of human fibroblasts and identified one serum that immunostained a distinct nuclear structure with a size and nuclear localization consistent with the Barr body. The number of these structures was consistent with the number of Barr bodies expected in diploid female fibroblasts containing two to five X chromosomes. Immunostaining with the serum followed by fluorescence in situ hybridization with a probe against XIST RNA demonstrated that the major fluorescent signal from the autoantibody colocalized with XIST RNA. Further analysis of the serum showed that it stains human metaphase chromosomes and a nuclear structure consistent with the inactive X in female mouse fibroblasts. However, it does not exhibit localization to a Barr body-like structure in female mouse embryonic stem cells or in cells from female mouse E7.5 embryos. The lack of staining of the inactive X in cells from female E7.5 embryos suggests the antigen(s) may be involved in X inactivation at a stage subsequent to initiation of X inactivation. This demonstration of an autoantibody recognizing an antigen(s) associated with the Barr body presents a strategy for identifying molecular components of the Barr body and examining the molecular basis of X inactivation.

X inactivation: Tsix and Xist as yin and yang

A new study shows that expression of Tsix, an antisense Xist gene, can be controlled by imprinting, and that high Tsix activity during X inactivation can protect the future active X chromosome from silencing by Xist. Tsix and Xist seem to have a yin and yang relationship, with opposite effects on X inactivation.

The carina as a landmark in central venous catheter placement

Location of the tip of a central venous catheter (CVC) within the pericardium has been associated with potentially lethal cardiac tamponade. Because the pericardium cannot be seen on chest x-ray (CXR), an alternative radiographic marker is needed for correct placement of CVCs. The anatomy of the region was studied in 34 cadavers. The carina was a mean (SEM) distance of 0.4 (0.1) cm above the pericardial sac as it transverses the superior vena cava (SVC). In no case was the carina located below the pericardial sac. The carina is a reliable, simple anatomical landmark for the correct placement of CVCs. In almost all cases, the carina is radiologically visible even in poor quality, portable CXRs. CVC tips should be located in the SVC above the level of the carina in order to avoid cardiac tamponade.

Absorption and hemodynamic effects of airway administration of adrenaline in patients with severe cardiac disease

BACKGROUND

If intravenous access cannot be attained during resuscitation of adult patients, endotracheal application of at least 2 mg of adrenaline is recommended. However, the effects of this intervention have not yet been demonstrated in adults.

OBJECTIVE

To demonstrate the effects of adrenaline administered through the airways.

DESIGN

Prospective clinical trial.

SETTING

Operating theater at university hospital.

PATIENTS

34 patients receiving implantable cardioverter defibrillators under general anesthesia.

INTERVENTION

When mean arterial pressure decreased below 80 mm Hg, 100 times the effective central intravenous dose of adrenaline (mean +/- SD, 1.3+/-0.6 mg [range, 0.7 to 3 mg]) was administered over 5 seconds into the endotracheal tube or through a bronchial catheter. Ten forced ventilations followed.

MEASUREMENTS

Hemodynamic variables were recorded with a polygraph recorder. Adrenaline levels were measured in 13 patients.

RESULTS

Plasma levels and arterial pressure increased in all patients (P < 0.002). Higher plasma levels (P < 0.039) and greater arterial pressure (P < 0.001) were achieved with this method than with intravenous injection. The effects of adrenaline did not differ between the two airway routes. Sustained ventricular arrhythmia did not occur.

CONCLUSION

These substantial effects support the standard recommendation to consider the airways as an alternate route for at least 2 mg of adrenaline during resuscitation.

Messenger RNAs encoding mouse histone macroH2A1 isoforms are expressed at similar levels in male and female cells and result from alternative splicing

Two protein isoforms of histone macroH2A1 (mH2A1) are found in mammalian cells. One isoform, mH2A1.2 is highly concentrated on the heterochromatinized inactive X chromosome (Xi) of female cells. mH2A1.2 protein is also present in male cells, but fails to form dense concentrations. Another protein isoform, mH2A1.1, differs from mH2A1.2 by a single short segment of amino acids. In this study, we cloned and characterized the genomic locus of the mouse mH2A1 gene and mapped it to chromosome 13. Two alternatively spliced transcripts derived from the mH2A1 locus are responsible for the generation of the two mH2A1 protein isoforms with mH2A1.2 mRNA being the most abundant spliced form in all tissues examined. The absolute amount of mH2A1 mRNA is similar in male and female cells for most tissues with the exception of testes where it is par-ticularly abundant. Both spliced forms are present in all adult tissues analyzed as well as in female embryonic stem cells. In contrast, male embryonic stem cells expressed mH2A1.1 at low levels if at all. The relatively abundant expression of mH2A1 in both sexes suggests that mH2A1 has functions in addition to a possible involvement in X chromosome inactivation.

Victor Ivánchich (1812-1892) and Josef Weiger (1810-1863): early cooperation of a urologist and an anesthesiologist

Today the cooperation of the highly developed specialities anesthesiology and urology is daily practice in every hospital and does not need further explanation in medical reports. The history of medicine tells us that the situation was different during the pioneer days of surgery in the last century. Although the statement that the patient underwent surgery while under general anesthesia was mostly included in the reports of operations at that time, the need for a specially trained doctor to perform anesthesia was hardly recognized. Most surgeons delegated this task to young colleagues or even to persons who had not been medically trained. The urologic surgeon Victor Ivánchich may have been an exception in including his special anesthesiologist Josef Weiger in several of his publications on lithotrity.

Mammalian X chromosome inactivation

X chromosome inactivation in mammals requires expression of the gene Xist, which maps to the X chromosome inactivation centre (Xic) and encodes an untranslated RNA. Truncation of Xist RNA by gene targeting is lethal for female embryos and prevents the inactivation of the X chromosome carrying the deletion. This indicates that Xist RNA is necessary for initiation and propagation of the inactivation process. Xist is transcribed from the inactive X and its expression is silenced by DNA methylation, suggesting that methylation is crucial for shielding the active X chromosome against the inactivation process. Gene transfer experiments using transgenes the size of yeast artificial chromosomes have determined that a 450 kb fragment of DNA carrying Xist acts as an inactivation centre and is sufficient for initiation, propagation and maintenance of the inactive state. The elements for counting and choosing X chromosomes are part of the transgene. We have shown that X inactivation is mediated by a post-translational mechanism, i.e. the stabilization of Xist RNA, rather than by the regulation of the Xist promoter.

[Cerebral hemodynamics during implantation of cardioverter-defibrillator systems]

OBJECTIVE

During ICD-implantation it is necessary to prove the function and to determine the optimal threshold by means of induced ventricular fibrillation (VF). Provoked cardiac arrests cause a circulator stop of the cerebral perfusion. Our aim was to examine the changes of cerebral blood flow velocity (CBFV(MCA)) after induced VF depending on the duration of fibrillation and prior values of CBFV(MCA).

PATIENTS AND METHODS

Sixty induced episodes of VF in 9 patients (mean age +/- SD 53.5 +/- 8 years) were examined during ICD-implantation. Beside the standardized anaesthesiological monitoring, transcranial Doppler sonography was used to record the cerebral blood flow velocity in the middle cerebri artery CBFV(MCA). The duration of the fibrillation-period and the range and duration of the CBFV increase during the post defibrillation-period were correlated. Additionally, we examined whether systematic differences existed between the episodes of each patient (time-trend) by means of 5 following episodes of a patient.

RESULTS

During all episodes of VF and hyperperfusion was present, that means a time interval showing increased values of CBFV(MCA), compared to the values present before VF. The duration of hyperperfusion depended significantly on the fibrillation time (r = 0.57; p < 0.001). The equation of regression is: hyperperfusion time = 11.1 + 1.22 x fibrillation time. The amount of hyperperfusion, that means the maximal CBFV after defibrillation, increase significantly with CBFV(MCA) before VF (correlation = 0.88; p < 0.001). The equations of regression is hyperperfusion height = 6.11 + 1.22 x CBFV(MCA) before VF. The duration of hyperperfusion is not influenced by the maximal CBFV(MCA) after defibrillation (r = 0.08; p = 0.52). In the examined patients no significant differences in the hyperperfusion time maximal CBFV(MCA) after defibrillation between the episodes were found.

CONCLUSION

After induced VF you always have to expect a reactive cerebral hyperperfusion. The amount of increase of CBFV after defibrillation depends on the prior values of CBFV before fibrillation and shows a nearly proportional relation to these. The duration of hyperperfusion shows a linear dependency on VF-times. This may show that we had VF-times, in which the cerebral autoregulation and other cerebral physiological reactions compensate the drop of the CBFV(MCA) during VF in the postfibrillation time. In further studies will be examined if there are similar changes in the cerebral metabolism as in CBFV(MCA).

Acute apnea caused by an epiglottic cyst

A life threatening complication in the course of routine sedation in a 5 year old child is reported in a case study. A retention cyst of the epiglottis was found to be responsible for obstruction of the larynx leading to acute apnea. The patient history revealed recurrent episodes of stridor previously diagnosed and treated as acute laryngotracheobronchitis as well as border line psychomotoric retardation. Cerebral magnetic resonance imaging was performed for neuroradiological evaluation. After administration of sedation the child presented with stridor and acute apnea. Emergency orotracheal intubation could prevent tracheotomy but was complicated by the unexpected presence of a tumor at the base of the tongue. Further evaluation revealed a large epiglottic cyst. After endoscopic removal of the cyst no further episodes of apnea or stridor were noted.

[Pulse oximetry and capnography in intensive care transportation: combined use reduces transportation risks]

OBJECTIVE

Due to the growing number of diagnostic and therapeutical procedures intensive-care patients must be transported intra- and interhospitally more often. These transports are among the most critical events during intensive-care therapy, with a high incidence of potentially life-threatening mishaps [23]. The aim of this study was to evaluate the possible benefit of the combined application of pulse oximetry and capnometry for patient safety during transport.

METHODS

In a prospective clinical study 48 mechanically ventilated patients were allocated at random in 2 main study groups, 24 patients were investigated during interhospital transportation with an ambulance car, the other 24 patients during intrahospital transports. They were classified according to APACHE II and TISS. Blood pressure, heart rate and arterial blood gases were measured at eleven selected times. Twelve randomly chosen patients out of each main study group were monitored additionally with pulse oximetry and capnometry. The results were compared using the Mann-Whitney-U test. P < or = 0.05 was considered significant.

RESULTS

Thirty-four patients had a TISS more than 40. The mean APACHE II-Score was 14 +/- 5. The overall incidence of potentially life-threatening mishaps was 9. Six out of these 9 occurred in the 24 patients with additional monitoring and were immediately detected by pulse oximetry or capnometry.

CONCLUSIONS

The combination of pulse oximetry and capnometry offers the possibility to detect potentially life-threatening problems in ventilated patients during transport. This allows for early therapeutical consequences and may help to reduce the risk of transports.

X chromosome inactivation is mediated by Xist RNA stabilization

Low level Xist expression can be detected from both active X chromosomes (Xa) in female embryonic stem cells prior to X inactivation. After differentiation, Xist is expressed at high levels only from the inactive X chromosome (Xi). Differentiating female cells increase Xist expression from the Xi prior to silencing low level Xist expression from the Xa. The transition from low level to high level expression is regulated by the stabilization of Xist transcripts at the Xi. We suggest that these developmentally modulated changes in Xist expression are regulated by several different mechanisms: factors that stabilize Xist transcripts at the Xi, an activity that blocks this stabilization at the Xa, and a mechanism that silences low level Xist expression from the Xa.