I. Tzanova

Perioperative anaesthetic management of mediastinal mass in adults

Mediastinal mass syndrome remains an anaesthetic challenge that cannot be underestimated. Depending on the localization and the size of the mediastinal tumour, the clinical presentation is variable ranging from a complete lack of symptoms to severe cardiorespiratory problems. The administration of general anaesthesia can be associated with acute intraoperative or postoperative cardiorespiratory decompensation that may result in death due to tumour-related compression syndromes. The role of the anaesthesiologist, as a part of the interdisciplinary treatment team, is to ensure a safe perioperative period. However, there is still no structured protocol available for perioperative anaesthesiological procedure. The aim of this article is to summarize the genesis of and the diagnostic options for mediastinal mass syndrome and to provide a solid detailed methodology for its safe perioperative management based on a review of the latest literature and our own clinical experiences. Proper anaesthetic management of patients with mediastinal mass syndrome begins with an assessment of the preoperative status, directed foremost at establishing the localization of the tumour and on the basis of the clinical and radiological findings, discerning whether any vital mediastinal structures are affected. We have found it helpful to assign ‘severity grade’ (using a three-grade clinical classification scale: ‘safe’, ‘uncertain’, ‘unsafe’), whereby each stage triggers appropriate action in terms of staffing and apparatus, such as the provision of alternatives for airway management, cardiopulmonary bypass and additional specialists. During the preoperative period, we are guided by a 12-point plan that also takes into account the special features of transportation into the operating theatre and patient monitoring. Tumour compression on the airways or the great vessels may create a critical respiratory and/or haemodynamic situation, and therefore the standard of intraoperative management includes induction of anaesthesia in the operating theatre on an adjustable surgical table, the use of short-acting anaesthetics, avoidance of muscle relaxants and maintenance of spontaneous respiration. In the case of severe clinical symptoms and large mediastinal tumours, we consider it absolutely essential to cannulate the femoral vessels preoperatively under local anaesthesia and to provide for the availability of cardiopulmonary bypass in the operating theatre, should extracorporeal circulation become necessary. The benefits of establishing vascular access under local anaesthesia clearly outweigh any associated degree of patient discomfort. In the case of patients classified as ‘safe’ or ‘uncertain’, a preoperative consensus with the surgeons should be reached as to the anaesthetic approach and the management of possible complications.

Adjustable tourniquet to manipulate pulmonary blood flow after Norwood operations

BACKGROUND Survival after first-stage palliative Norwood operations for single ventricle with systemic outflow obstruction is mainly dependent on a balanced ratio of pulmonary blood flow to systemic blood flow. Here we report the clinical results using a modified technique that allows a controlled systemic-to-pulmonary shunt flow to prevent pulmonary overcirculation. METHODS From 1995 to 1998, of 26 infants undergoing first-stage palliative Norwood operations, 7 had placement of an adjustable tourniquet around a modified right Blalock-Taussig shunt. RESULTS Hospital survival was 20 of 26 patients (77%). All 7 patients in whom snaring of the shunt was indicated survived. Two patients underwent repeated adjustment, in 5 patients the tourniquet could be removed during delayed sternal closure, and 2 patients were discharged with the shunt partially snared. CONCLUSIONS The snare-controlled systemic-to-pulmonary shunt allows improved hemodynamic stability after reconstructive surgery for hypoplastic left heart syndrome or other similar complex cardiac defects by reducing the risk of pulmonary overcirculation. It is simple and rapidly executed. The option of graded banding of the shunt depending on the hemodynamic situation increases flexibility and safety after cardiopulmonary bypass or at any time in the postoperative period.

Rectal pH in children

In an attempt to establish normal values for rectal pH in children, we have measured pH in 100 paediatric patients. Measurement of rectal pH was performed in 25 infants and 75 children (27 girls and 73 boys) using a monocrystalline antimony electrode. Rectal pH was 9.6 ± 0.9 (mean ± SD, range 7.2 to 12.1) and was independent of sex, age and nutrition. This wide range of rectal pH values offers a possible explanation for the widely scattered bioavailability of drugs administered by the rectal route. Mean rectal pH was considerably higher than that reported for adults; this unexpected alkalinity should be taken into account, when drug formulations are considered for rectal administration in children.RésuméDans une tentative d’établir les valeurs normales du pH rectal chez les enfants, on a mesuré le pH chez 100 patients pédiatriques. La mesure du pH rectal fut faite chez 25 nouveau-nés et 75 enfants (27 filles et 73 garçons) utilisant des électrodes d’antimoine monocrystalline. Le pH rectal était de 9.6 ± 0.9 (movenne ± SD, écart 7.2 à 12.1 ) el fut indépendant du sexe, âge et nutrition. Cet grand écart du pH rectal nous offre possiblement une explication quant à la raison du grand écart de bio-disponibilité des médicaments administrés par voie rectale. Le pH moyen rectal est considerablement supérieur à celui rapporté chez l’adulte; cette alcalinité inexpliquée doit être prise en considération quand on formule des médicaments pour administration rectale chez les enfants

Multicentre evaluation of in vitro contracture testing with bolus administration of 4-chloro-m-cresol for diagnosis of malignant hyperthermia susceptibility.

Background and objective: The in vitro contracture test with halothane and caffeine is the gold standard for the diagnosis of susceptibility to malignant hyperthermia (MH). However, the sensitivity of the in vitro contracture test is between 97 and 99% and its specificity is 78-94% with the consequence that false-negative as well as false-positive test results are possible. 4-Chloro-m-cresol is potentially a more specific test drug for the in vitro contracture test than halothane or caffeine. This multicentre study was designed to investigate whether an in vitro contracture test with bolus administration of 4-chloro-m-cresol can improve the accuracy of the diagnosis of susceptibility to MH. Methods: Three hundred and fifty-two patients from 11 European MH laboratories participated in the study. The patients were first classified as MH susceptible, MH normal or MH equivocal by the in vitro contracture test according to the European MH protocol. Muscle specimens surplus to diagnostic requirements were used in this study (MH susceptible = 103 viable samples; MH equivocal = 51; MH normal = 204). 4-Chloro-m-cresol was added to achieve a concentration of 75 μmol L−1 in the tissue bath. The in vitro effects on contracture development and muscle twitch were observed for 60 min. Results: After bolus administration of 4-chloro-m-cresol, 75 μmol L−1, 99 of 103 MH-susceptible specimens developed marked muscle contractures. In contrast, only two of 204 MH-normal specimens showed an insignificant contracture development following 4-chloro-m-cresol. From these results, a sensitivity rate of 96.1% and a specificity rate of 99.0% can be calculated for the in vitro contracture test with bolus administration of 4-chloro-m-cresol 75 μmol L−1. Forty-three patients were diagnosed as MH equivocal, but only specimens from 16 patients developed contractures in response to 4-chloro-m-cresol, indicating susceptibility to MH. Conclusions: The in vitro contracture test with halothane and caffeine is well standardized in the European and North American test protocols. However, this conventional test method is associated with the risk of false test results. Therefore, an improvement in the diagnosis of MH is needed. Regarding the results from this multicentre study, the use of 4-chloro-m-cresol could increase the reliability of in vitro contracture testing.

Neuromonitoring and neuroprotection in cardiac anaesthesia. Nationwide survey conducted by the Cardiac Anaesthesia Working Group of the German Society of Anaesthesiology and Intensive Care Medicine

OBJECTIVE The primary objective of this nationwide survey carried out in department of cardiac anesthesia in Germany was to identify current practice with regard to neuromonitoring und neuroprotection. METHODOLOGY The data are based on a questionnaire sent out to all departments of cardiac anesthesia in Germany between October 2007 und January 2008. The anonymized questionnaire contained 26 questions about the practice of preoperative evaluation of cerebral vessels, intra-operative use of neuromonitoring, the nature und application of cerebral protective measures, perfusion management during cardiopulmonary bypass, postoperative evaluation of neurological status, and training in the field of cerebral monitoring. RESULTS Of the 80 mailed questionnaires 55% were returned and 90% of department evaluated cerebral vessels preoperatively with duplex ultrasound. The methods used for intra-operative neuromonitoring are electroencephalography (EEG, 60%) for type A dissections (38.1%), for elective surgery on the thoracic and thoraco-abdominal aorta (34.1% and 31.6%, respectively) and in carotid surgery (43.2%) near infrared spectroscopy (40%), evoked potentials (30%) and transcranial Doppler sonography (17.5%), with some centers using combined methods. In most departments the central nervous system is not subjected to monitoring during bypass surgery, heart valve surgery, or minimally invasive surgery. Cerebral protective measures used comprise patient cooling on cardio-pulmonary bypass (CPB 100%), extracorporeal cooling of the head (65%) and the administration of corticosteroids (58%), barbiturates (50%) and antiepileptic drugs (10%). Neuroprotective anesthesia consists of administering inhalation anesthetics (32.5%; sevoflurane 76.5%) and intravenous anesthesia (20%; propofol and barbiturates each accounting for 46.2%). Of the departments 72.5% cool patients as a standard procedure for surgery involving cardiovascular arrest and 37.5% during all surgery using CPB. In 84.6% of department CPB flow equals calculated cardiac output (CO) under normothermia, while the desired mean arterial pressure (MAP) varies between 60 and 70 mmHg (43.9%) and between 50 and 60 mmHg (41.5%), respectively. At body temperatures less than 18 degrees C CPB flow is reduced below the calculated CO (70%) while 27% of departments use normothermic flow rates. The preferred MAP under hypothermia is between 50 and 60 mmHg (59%). The results of intra-operative neuromonitoring are documented on the anesthesia record (77%). In 42.5% of the departments postoperative neurological function is estimated by the anesthesiologist. Continuing education sessions pertaining to neuromonitoring are organized on a regular basis in 32.5% of the departments and in 37.5% individual physicians are responsible for their own neuromonitoring education. CONCLUSION The present survey data indicate that neuromonitoring and neuroprotective therapy during CPB is not standardized in cardiac anesthesiology departments in Germany. The systemic use of available methods to implement multimodal neuromonitoring would be desirable.

A case of intrapulmonary transmission of air while transitioning a patient from a sitting to a supine position after venous air embolism during a craniotomy

PurposeSince certain surgical procedures still require a sitting or reverse Trendelenburg position, it remains important to evaluate the risk for paradoxical embolization. Intracardiac shunting, the most common cause being a patent foramen ovale, can be excluded by contrast-enhanced transesophageal echocardiography. There are, however, less described cases which result from patency of intrapulmonary functional arteriovenous anastomoses and lead to extra-cardiac paradoxical air embolism during anesthesia. We report a unique case to increase awareness of this real and potentially dangerous complication.Clinical featuresA 52-yr-old male was scheduled for resection of a tumour at the cerebellopontine angle. Preoperative evaluation excluded intracardiac shunts. During a craniotomy in the sitting position, recurrent venous air emboli entered the patient’s right heart, leading to a sudden decline in end-tidal CO2, an increase in PaCO2, and a reduction of PaO2. The exact source of surgical entrance could not be identified; therefore, the surgical wound was closed provisionally and the patient was repositioned supine to prevent further venous air emboli. During transition to the supine position, we observed clinically significant crossover of air into the left heart originating from the left pulmonary vein, as detected by transesophageal echocardiography. In all likelihood, the etiology was an opening of intrapulmonary right-to-left anastomoses. The patient recovered without neurological or pulmonary sequelae.ConclusionIn the presence of massive venous air emboli, intrapulmonary right-to-left paradoxical air emboli can occur while intraoperatively transitioning a patient from the sitting to the supine position.RésuméObjectifDans la mesure où certaines interventions chirurgicales requièrent la position assise ou en Trendelenburg inversé, il est important d’évaluer le risque d’embolie paradoxale. Une communication intracardiaque (la cause la plus fréquente étant un foramen ovale perméable) peut être exclue par échocardiographie transœsophagienne avec produit de contraste. Il y a, toutefois, des cas moins souvent décrits qui peuvent être dus à la perméabilité d’anastomoses artério-veineuses fonctionnelles et aboutir à une embolie gazeuse paradoxale extracardiaque au cours de l’anesthésie. Nous décrivons un cas unique pour sensibiliser à l’existence de cette complication réelle et potentiellement dangereuse.Caractéristiques cliniquesUn homme âgé de 52 ans devait subir la résection d’une tumeur de l’angle pontocérébelleux. Le bilan préopératoire avait exclu l’existence de communications intracardiaques. Au cours de la craniotomie en position assise, des embolies d’air veineux récidivants ont pénétré dans le cœur droit du patient, aboutissant à une chute soudaine du CO2 télé-expiratoire, à une augmentation de la PaCO2 et à une baisse de la PaO2. La source exacte de la brèche chirurgicale n’a pu être identifiée; en conséquence, la plaie chirurgicale a été fermée provisoirement et le patient a été repositionné en décubitus dorsal pour prévenir d’autres embolies gazeuses veineuses. Au cours du changement de position vers le décubitus dorsal, nous avons observé un passage d’air cliniquement significatif dans le cœur gauche en provenance de la veine pulmonaire gauche, détecté par l’échocardiographie transœsophagienne. En toute probabilité, la cause en était l’ouverture d’anastomoses droites-gauches intrapulmonaires. Le patient s’est rétabli sans séquelles neurologiques ou pulmonaires.ConclusionEn présence d’embolies gazeuses veineuses massives, une embolie gazeuse paradoxale droite-gauche intrapulmonaire peut survenir en cours d’intervention lors du changement de position du patient, de la position assise au décubitus dorsal.

Neuromonitoring und Neuroprotektion in der Kardioanästhesie

OBJECTIVE The primary objective of this nationwide survey carried out in department of cardiac anesthesia in Germany was to identify current practice with regard to neuromonitoring und neuroprotection. METHODOLOGY The data are based on a questionnaire sent out to all departments of cardiac anesthesia in Germany between October 2007 und January 2008. The anonymized questionnaire contained 26 questions about the practice of preoperative evaluation of cerebral vessels, intra-operative use of neuromonitoring, the nature und application of cerebral protective measures, perfusion management during cardiopulmonary bypass, postoperative evaluation of neurological status, and training in the field of cerebral monitoring. RESULTS Of the 80 mailed questionnaires 55% were returned and 90% of department evaluated cerebral vessels preoperatively with duplex ultrasound. The methods used for intra-operative neuromonitoring are electroencephalography (EEG, 60%) for type A dissections (38.1%), for elective surgery on the thoracic and thoraco-abdominal aorta (34.1% and 31.6%, respectively) and in carotid surgery (43.2%) near infrared spectroscopy (40%), evoked potentials (30%) and transcranial Doppler sonography (17.5%), with some centers using combined methods. In most departments the central nervous system is not subjected to monitoring during bypass surgery, heart valve surgery, or minimally invasive surgery. Cerebral protective measures used comprise patient cooling on cardio-pulmonary bypass (CPB 100%), extracorporeal cooling of the head (65%) and the administration of corticosteroids (58%), barbiturates (50%) and antiepileptic drugs (10%). Neuroprotective anesthesia consists of administering inhalation anesthetics (32.5%; sevoflurane 76.5%) and intravenous anesthesia (20%; propofol and barbiturates each accounting for 46.2%). Of the departments 72.5% cool patients as a standard procedure for surgery involving cardiovascular arrest and 37.5% during all surgery using CPB. In 84.6% of department CPB flow equals calculated cardiac output (CO) under normothermia, while the desired mean arterial pressure (MAP) varies between 60 and 70 mmHg (43.9%) and between 50 and 60 mmHg (41.5%), respectively. At body temperatures less than 18 degrees C CPB flow is reduced below the calculated CO (70%) while 27% of departments use normothermic flow rates. The preferred MAP under hypothermia is between 50 and 60 mmHg (59%). The results of intra-operative neuromonitoring are documented on the anesthesia record (77%). In 42.5% of the departments postoperative neurological function is estimated by the anesthesiologist. Continuing education sessions pertaining to neuromonitoring are organized on a regular basis in 32.5% of the departments and in 37.5% individual physicians are responsible for their own neuromonitoring education. CONCLUSION The present survey data indicate that neuromonitoring and neuroprotective therapy during CPB is not standardized in cardiac anesthesiology departments in Germany. The systemic use of available methods to implement multimodal neuromonitoring would be desirable.

Anästhesiologisches Management bei mediastinaler Raumforderung

ZusammenfassungDas perioperative Management von Patienten mit mediastinaler Raumforderung ist eine besondere klinische Herausforderung für unser Fachgebiet. Zwar stellt die Regionalanästhesie, als Verfahren der ersten Wahl, eine sichere und einfache Technik dar, doch häufig ist sie operationsbedingt nicht realisierbar. Für diese Fälle verbleibt die Allgemeinanästhesie, deren Durchführung wegen tumorbedingter Kompressionssyndrome eine akute respiratorische und hämodynamische Dekompensation (Mediastinal-Mass-Syndrom) auslösen kann. Die adäquate Versorgung der Patienten beginnt mit der präoperativen Risikoklassifizierung anhand klinisch-radiologischer Befunde. Neben Anamnese, Röntgen und computertomographischer Untersuchung des Thorax, werden dynamische Verfahren, wie Pneumotachographie und Echokardiographie zur Verifizierung möglicher intraoperativer Verdrängungserscheinungen herangezogen. Die Narkoseleitung erfolgt wach-fiberoptisch, wobei der Patient unter Erhaltung der Spontanatmung intubiert wird. Die Anästhesie wird inhalativ oder intravenös mit kurzwirksamen Präparaten fortgeführt; Muskelrelaxantien werden, falls operationstechnisch möglich, nicht verwendet. Wurde die Anästhesie als „ungewiss“ oder „gefährlich“ charakterisiert, werden je nach Ort der tumorbedingten Kompression (tracheobronchial, pulmonalarteriell, caval) alternative Techniken der Atemwegssicherung (unterschiedliche Tuben, rigides Bronchoskop) bereitgestellt und extrakorporale Oxygenierungsverfahren (Herz-Lungen-Maschine, HLM) im Operationssaal vorbereitet. Bei schwerer klinischer Symptomatik und ausgedehntem Mediastinaltumor erfolgt zusätzlich die präoperative Kanülierung der Femoralisgefäße in Lokalanästhesie. Neben der Sicherstellung der technischen und personellen Voraussetzungen ist die interdisziplinäre Zusammenarbeit der beteiligten Fachabteilungen eine Grundvoraussetzung für die sichere Patientenversorgung.AbstractThe perioperative management of patients with mediastinal masses is a special clinical challenge in our field. Even though regional anaesthesia is normally the first choice, in some cases it is not feasible due to the method of operation. In these cases general anaesthesia is the second option but can lead to respiratory and haemodynamic decompensation due to tumor-associated compression syndrome (mediastinal mass syndrome). The appropriate treatment begins with the preoperative risk classification on the basis of clinical and radiological findings. In addition to anamnesis, chest radiograph, and CT, dynamical methodes (e.g. pneumotachography and echocardiography) should be applied to verify possible intraoperative compession syndromes. The induction of general anaesthesia is to be realized in awake-fiberoptic intubation with introduction of the tube via nasal route while maintaining the spontanious breathing of the patient. The anaesthesia continues with short effective agents applied inhalative or iv. If possible from the point of operation, agents of muscle ralaxation are not to be applied. If the anaesthesia risk is classified as uncertain or unsafe, depending on the location of tumor compression (tracheobronchial tree, pulmonary artery, superior vena cava), alternative techniques of securing the respiratory tract (different tubes, rigid bronchoscope) and cardiopulmonary bypass with extracorporal oxygen supply are prepared. For patients with severe clinical symptoms and extensive mediastinal mass, the preoperative cannulation of femoral vessels is also recommended. In addition to fulfilling technical and personnel requirements, an interdisciplinary cooperation of participating fields is the most important prerequisite for the optimal treatment of patients.

Anaesthesiological management of mediastinal tumors

ZusammenfassungDas perioperative Management von Patienten mit mediastinaler Raumforderung ist eine besondere klinische Herausforderung für unser Fachgebiet. Zwar stellt die Regionalanästhesie, als Verfahren der ersten Wahl, eine sichere und einfache Technik dar, doch häufig ist sie operationsbedingt nicht realisierbar. Für diese Fälle verbleibt die Allgemeinanästhesie, deren Durchführung wegen tumorbedingter Kompressionssyndrome eine akute respiratorische und hämodynamische Dekompensation (Mediastinal-Mass-Syndrom) auslösen kann. Die adäquate Versorgung der Patienten beginnt mit der präoperativen Risikoklassifizierung anhand klinisch-radiologischer Befunde. Neben Anamnese, Röntgen und computertomographischer Untersuchung des Thorax, werden dynamische Verfahren, wie Pneumotachographie und Echokardiographie zur Verifizierung möglicher intraoperativer Verdrängungserscheinungen herangezogen. Die Narkoseleitung erfolgt wach-fiberoptisch, wobei der Patient unter Erhaltung der Spontanatmung intubiert wird. Die Anästhesie wird inhalativ oder intravenös mit kurzwirksamen Präparaten fortgeführt; Muskelrelaxantien werden, falls operationstechnisch möglich, nicht verwendet. Wurde die Anästhesie als „ungewiss“ oder „gefährlich“ charakterisiert, werden je nach Ort der tumorbedingten Kompression (tracheobronchial, pulmonalarteriell, caval) alternative Techniken der Atemwegssicherung (unterschiedliche Tuben, rigides Bronchoskop) bereitgestellt und extrakorporale Oxygenierungsverfahren (Herz-Lungen-Maschine, HLM) im Operationssaal vorbereitet. Bei schwerer klinischer Symptomatik und ausgedehntem Mediastinaltumor erfolgt zusätzlich die präoperative Kanülierung der Femoralisgefäße in Lokalanästhesie. Neben der Sicherstellung der technischen und personellen Voraussetzungen ist die interdisziplinäre Zusammenarbeit der beteiligten Fachabteilungen eine Grundvoraussetzung für die sichere Patientenversorgung.AbstractThe perioperative management of patients with mediastinal masses is a special clinical challenge in our field. Even though regional anaesthesia is normally the first choice, in some cases it is not feasible due to the method of operation. In these cases general anaesthesia is the second option but can lead to respiratory and haemodynamic decompensation due to tumor-associated compression syndrome (mediastinal mass syndrome). The appropriate treatment begins with the preoperative risk classification on the basis of clinical and radiological findings. In addition to anamnesis, chest radiograph, and CT, dynamical methodes (e.g. pneumotachography and echocardiography) should be applied to verify possible intraoperative compession syndromes. The induction of general anaesthesia is to be realized in awake-fiberoptic intubation with introduction of the tube via nasal route while maintaining the spontanious breathing of the patient. The anaesthesia continues with short effective agents applied inhalative or iv. If possible from the point of operation, agents of muscle ralaxation are not to be applied. If the anaesthesia risk is classified as uncertain or unsafe, depending on the location of tumor compression (tracheobronchial tree, pulmonary artery, superior vena cava), alternative techniques of securing the respiratory tract (different tubes, rigid bronchoscope) and cardiopulmonary bypass with extracorporal oxygen supply are prepared. For patients with severe clinical symptoms and extensive mediastinal mass, the preoperative cannulation of femoral vessels is also recommended. In addition to fulfilling technical and personnel requirements, an interdisciplinary cooperation of participating fields is the most important prerequisite for the optimal treatment of patients.

Homozygote und „compound“-heterozygote RYR1 -Mutationen

BACKGROUND Malignant hyperthermia (MH) is a life-threatening, acute pharmacogenetic disorder mostly due to heterozygous mutations in the ryanodin receptor 1 (RYR1) gene. Diagnosis is generally confirmed by the in vitro contracture test (IVCT). In this study the genotype-phenotype correlation was analyzed and the presumed prevalence of MH is discussed. PATIENTS AND METHODS After the diagnosis of MH susceptibility by the IVCT DNA samples of 44 patients were analyzed for mutations in the RYR1 gene using the polymerase chain reaction and sequencing. For genotype-phenotype correlation, the mutation analysis data were compared with the IVCT data. RESULTS Out of the 44 patients tested 13 were identified with a heterozygous mutation, 1 patient with a homozygous mutation (c.1840C>T) and 1 patient with compound heterozygous mutations (c.1840C>T and c.6487C>T). The two patients with two mutated alleles showed a stronger response in the IVCT compared to those with only one mutated allele. Patients with one RYR1 mutation displayed significantly higher contractures in the IVCT than patients without RYR1 mutations. CONCLUSION In the two patients described the presence of two mutated RYR1 alleles seemed to have an additive effect on the functional restriction of the (RYR1 receptor and to lead to a stronger response both in the IVCT and with regard to clinical signs. The patients with no detected RYR1 mutations possibly have a RYR1 mutation with smaller effects outside the hot spot regions tested and/or false positive IVCT results. The data from a small patient group indicate a substantially higher prevalence of MH with a correspondingly lower penetrance in the German population than previously assumed.