Right ventricular stroke volume variation: a tool to assess right ventricular volume responsiveness.

BACKGROUND: So far, only left ventricular functional preload indices are used as a routine to assess volume responsiveness. Right ventricular (RV) functional preload indices have been described, but offer no continuous monitoring. METHODS: Following ethical approval, a pressure-induced right ventricular failure (RVF) was induced with continuous infusion of a thromboxane-A2-analogue (U46619) in 15 anesthetized and ventilated pigs. Before and after increasing mean pulmonary artery pressure (MPAP) by 50%, right ventricular stroke volume variation (RVSVV) was assessed with an ultrasonic pulmonary artery flow probe. Measurements were repeated following volume depletion (- 300 mL) and stepwise retransfusion (200 mL of whole blood and 200 mL of a colloid solution). RESULTS: A significant and systematic increase in RVSVV during induction of RVF was observed. Volume depletion led to an increase in RVSVV and re-transfusion led to a decrease in RVSVV. RVSVV was higher and a significant decrease in RVSVV was present in all animals experiencing an increase in CO by more than 5% during retransfusion. CONCLUSION: RVSVV seems to reflect volume requirement of the right ventricle and it might prove a reliable parameter to assess volume responsiveness in RVF.

Mechanotransduction in the lungs.

Mechanical ventilation may induce or aggravate lung injury, a phenomenon known as ventilator induced lung injury (VILI). On a macroscopic level, the effects of mechanical stress and strain on lung tissue are well described. Increased tidal volumes may lead to volutrauma, raised airway pressures may cause barotrauma and cyclic collapse and reopening of alveolar units contributes to atelectrauma. These three harmful mechanisms may lead to local and systemic pulmonary inflammatory response known as biotrauma. The purpose of this review was to elucidate fundamental mechanisms involved in the mechanotransduction of mechanical stimuli on a cellular level. Bronchial epithelial cells in the distal airways as well as alveolar epithelial cells are exposed to a variety of mechanical forces. These cells are involved in sensing and translation of mechanical stimuli into an inflammatory response. This review provides insight into current knowledge of cellular and molecular pathways during the process of pulmonary epithelial mechanosensation and mechanotransduction under different mechanical conditions. Since evidence for specific pathways is generally lacking in some fields of alveolar epithelial mechanotransduction, this article aims at providing reasonable hypothesis for further investigation.

[Pharmacogenetics. Clinical relevance in anesthsiology]. / Pharmakogenetik. Klinische Bedeutung in der Anästhesiologie.

BACKGROUND: Pharmacogenetics deals with hereditary factors which influence the pharmacodynamics and pharmacokinetics of drugs leading to individual diverse reactions. Also in anesthesiology differences in the pharmacogenetics of patients can lead to relevant alterations in the pharmacodynamics of drugs. AIM: This article provides a summary of polymorphisms relevant to commonly used anesthetic agents and the clinical relevance in patients treated with these compounds. It describes the possibilities, the problems and limits of pharmacogenetic diagnostics and therapy and explains how this follows the target of individualized medicine. MATERIAL AND METHODS: This article describes in detail the alterations in pharmacodynamics and pharmakokinetics relevant for anesthesia and their clinical significance. Based on the results of current studies, an overview of the most important drugs in anesthesiology with significant polymorphisms is given. These include opioids, muscle relaxants, volatile anesthetic agents, non-steroidal anti-inflammatory drugs (NSAIDs), benzodiazepines, antiemetics and cardiovascular drugs as well as platelet aggregation inhibitors, anticoagulants and the so-called new oral anticoagulants. RESULTS: Genetic alterations can lead to substantial modifications in the effectiveness of drugs. Genetic alterations of opioid receptors and the enzyme cytochrome P450 (CYP) 2D6 can result in a failure of analgesia after administration of opioids. Alterations in plasma cholinesterase activity are associated with a prolonged effectiveness of muscle relaxants. Polymorphisms in ryanodine receptors can contribute to the development of the feared MH in patients after administration of volatile anesthetics or succinylcholine. CONCLUSION: The study results presented here emphasize that these days knowledge on pharmacogenetics should not be missing in modern induction of anesthesia. In the future a blood sample could enable physicians to identify pharmacologically relevant markers. And these could guide the decision on the prescription of drugs and their appropriate dose, in order to achieve the lowest risk of side effects and the highest effectiveness of the active substance.

Comparison of an automated respiratory systolic variation test with dynamic preload indicators to predict fluid responsiveness after major surgery.

BACKGROUND: Predicting the response of cardiac output to volume administration remains an ongoing clinical challenge. The objective of our study was to compare the ability to predict volume responsiveness of various functional measures of cardiac preload. These included pulse pressure variation (PPV), stroke volume variation (SVV), and the recently launched automated respiratory systolic variation test (RSVT) in patients after major surgery. METHODS: In this prospective study, 24 mechanically ventilated patients after major surgery were enrolled. Three consecutive volume loading steps consisting of 300 ml 6% hydroxyethylstarch 130/0.4 were performed and cardiac index (CI) was assessed by transpulmonary thermodilution. Volume responsiveness was considered as positive if CI increased by >10%. RESULTS: In total 72 volume loading steps were analysed, of which 41 showed a positive volume response. Receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.70 for PPV, 0.72 for SVV and 0.77 for RSVT. Areas under the curves of all variables did not differ significantly from each other (P>0.05). Suggested cut-off values were 9.9% for SVV, 10.1% for PPV, and 19.7° for RSVT as calculated by the Youden Index. CONCLUSION: In predicting fluid responsiveness the new automated RSVT appears to be as accurate as established dynamic indicators of preload PPV and SVV in patients after major surgery. The automated RSVT is clinically easy to use and may be useful in guiding fluid therapy in ventilated patients.

Changes in sevoflurane plasma concentration with delivery through the oxygenator during on-pump cardiac surgery.

BACKGROUND: It is unclear what factors affect the uptake of sevoflurane administered through the membrane oxygenator during cardiopulmonary bypass (CPB) and whether this can be monitored via the oxygenator exhaust gas. METHODS: Stable delivery of sevoflurane was administered to 30 elective cardiac surgery patients at 1.8 vol% (inspiratory) via the anaesthetic circuit and ventilator. During CPB, sevoflurane was administered in the oxygenator fresh gas supply (Compactflo Evolution™; Sorin Group, Milano, Italy). Sevoflurane plasma concentration (SPC) was measured using gas chromatography. Changes were correlated with bispectral index (BIS), patient temperature, haematocrit, plasma albumin concentration, oxygenator fresh gas flow, and the sevoflurane concentration in the oxygenator exhaust at predefined time points. RESULTS: The mean SPC pre-bypass was 54.9 µg ml(-1) [95% confidence interval (CI): 50.6-59.1]. SPC decreased to 43.2 µg ml(-1) (95% CI: 40.3-46.1; P<0.001) after initiation of CPB, and was lower still during rewarming and weaning from bypass, 39.4 µg ml(-1) (95% CI: 36.6-42.3; P<0.001). BIS did not exceed a value of 55. SPCs were higher during hypothermia (P<0.001) and with an increase in oxygenator fresh gas flow (P=0.015), and lower with haemodilution (P=0.027). No correlation was found between SPC and the concentration of sevoflurane in the oxygenator exhaust gas (r=-0.04; 95% CI: -0.18 to 0.09; P=0.53). CONCLUSIONS: The uptake of sevoflurane delivered via the membrane oxygenator during CPB seems to be affected by hypothermia, haemodilution, and changes in the oxygenator fresh gas supply flow. Measuring the concentration of sevoflurane in the exhaust from the oxygenator is not useful for monitoring sevoflurane administration during bypass.

[When the resting membrane potential becomes restless. Acute hyperkalemia in the perioperative phase]. / Wenn das Ruhemembranpotenzial aus der Ruhe kommt. Akute Hyperkaliämie in der perioperativen Phase.

Acute hyperkalemia is a life-threatening event and often occurs abruptly and without warning in the perioperative field. Risk factors are found on multiple levels as they can derive from a patients pre-existing condition or result from the surgical intervention or management of anesthesia. The therapy of hyperkalemia depends on the dimensions of electrolyte disturbance and a distinction can be made between therapeutic measures with a rapid and those with a long-term effect.

[Intraoperative electrophysiological monitoring with evoked potentials]. / Intraoperatives elektrophysiologisches Monitoring mit evozierten Potenzialen.

During the last 30 years intraoperative electrophysiological monitoring (IOEM) has gained increasing importance in monitoring the function of neuronal structures and the intraoperative detection of impending new neurological deficits. The use of IOEM could reduce the incidence of postoperative neurological deficits after various surgical procedures. Motor evoked potentials (MEP) seem to be superior to other methods for many indications regarding monitoring of the central nervous system. During the application of IOEM general anesthesia should be provided by total intravenous anesthesia with propofol with an emphasis on a continuous high opioid dosage. When intraoperative MEP or electromyography guidance is planned, muscle relaxation must be either completely omitted or maintained in a titrated dose range in a steady state. The IOEM can be performed by surgeons, neurologists and neurophysiologists or increasingly more by anesthesiologists. However, to guarantee a safe application and interpretation, sufficient knowledge of the effects of the surgical procedure and pharmacological and physiological influences on the neurophysiological findings are indispensable.

[Undergraduate teaching of anaesthesiology : a nationwide survey in Germany]. / Universitäre Lehre der Anästhesiologie : Bestandsaufnahme in Deutschland.

BACKGROUND: In 2003 anaesthesiology was implemented as a compulsory speciality of undergraduate teaching in Germany due to the revised regulations of medical education. Besides the preexisting subject of emergency medicine an obligatory course in anaesthesiology was introduced. Thus anaesthesiology has gained considerable importance in all medical faculties. To gain insight into the current status of undergraduate medical education in the university departments of anaesthesiology a nationwide survey at all university departments in Germany was initiated. METHODS: In cooperation with the German Society of Anaesthesiology and Intensive Care Medicine (DGAI) a standardized questionnaire was developed and sent to 36 departments of anaesthesiology of all German medical faculties. Questions concerned the structure of the respective curriculum, learning goals, teaching, assessment and evaluation methods as well as facultative courses. RESULTS: Of the 36 university departments of anaesthesiology, 35 returned the questionnaire. In 66% undergraduate education in anaesthesiology is part of the fourth or fifth year of medical training. In 91% of the faculties lectures were accompanied by teaching in small student groups. A simulator-based training is integrated either in anaesthesiology and/or in emergency medicine in 91% of the departments of anaesthesiology. In 69% of the departments contents of anaesthesia, critical care medicine, emergency medicine and pain management are an integral part of undergraduate teaching in anaesthesiology. The primary learning goals are directed towards general anaesthesia and there is less focus on topics of preoperative or postoperative care, such as preoperative risk evaluation, postoperative pain management and regional anaesthesia. Besides a multiple choice test (91%) oral (63%) and/or practical examinations (71%) are used as assessment tools. In 71% of the medical faculties the respective departments of anaesthesiology are leading and organising skills laboratories. In student evaluations anaesthesiology achieved best ranking in 66% of the medical faculties compared to other specialties. The possibility to take an elective course in anaesthesiology exists in 74% of the faculties. Half of these faculties organize this elective as a longitudinal course for one complete semester, the other half as a full time course over mostly 1 or 2 weeks. At present E-learning plays a minor role. CONCLUSIONS: This survey provides detailed information about the current status of undergraduate teaching of the university departments of anaesthesiology in Germany. The study shows a remarkable consistency of structure, contents and methods of education in anaesthesiology throughout all university departments of anaesthesiology. This information is the basis for triggering synergistic effects, for improving educational standards in anaesthesiology and for introducing a platform for developing modern learning media, e.g. through the scientific society DGAI.

Effects of one-lung ventilation on thermodilution-derived assessment of cardiac output.

BACKGROUND: Cardiac output (CO) monitoring can be useful in high-risk patients during one-lung ventilation (OLV), but it is unclear whether thermodilution-derived CO monitoring is valid during OLV. Therefore, we compared pulmonary artery (CO(PATD)) and transcardiopulmonary thermodilution (CO(TPTD)) with an experimental reference in a porcine model. METHODS: CO(PATD) and CO(TPTD) were measured in 23 pigs during double-lung ventilation (DLV) and 15 min after the onset of OLV, during conditions of normovolaemia and after haemorrhage. An ultrasonic flow probe placed around the pulmonary artery (CO(PAFP)) was used for reference. RESULTS: The range of CO in these experiments was 1.5-3 litre min(-1). Normovolaemia: during DLV and conditions of normovolaemia, the mean (95% limits of agreement) bias for CO(PATD) compared with CO(PAFP) was -0.05 (-0.92 and 0.83) litre min(-1), and 0.58 (-0.40 and 1.55) litre min(-1) for CO(TPTD). During OLV, the bias for CO(PATD) remained unchanged at 0.08 (-0.51 and 0.66) litre min(-1), P=0.15, and the bias for CO(TPTD) increased significantly to 0.85 (0.05 and 1.64) litre min(-1), P=0.047. Hypovolaemia: during DLV, the bias for CO(PATD) compared with CO(PAFP) was 0.22 (-0.20 and 0.66) litre min(-1) and for CO(TPTD) was 0.60 (0.12 and 1.10) litre min(-1). There was no significant change of bias during OLV for CO(PATD) [0.30 (-0.10 and 0.70) (litre min(-1)), P=0.25] or bias CO(TPTD) [0.72 (0.21 and 1.22) (litre min(-1)), P=0.14]. Trending ability during OLV, quantified by the mean of angles θ, showed good values for both CO(PATD) (θ=11.2°) and CO(TPTD) (θ=1.3°). CONCLUSIONS: CO(TPTD) is, to some extent, affected by OLV, whereas CO(PATD) is unchanged. Nonetheless, both methods provide an acceptable estimation of CO and particularly of relative changes of CO during OLV.

[Severe muscular dystrophy and pregnancy: interdisciplinary challenge]. / Schwere Muskeldystrophie und Schwangerschaft: Interdisziplinäre Herausforderung.

The muscular dystrophies are degenerative muscle diseases characterized by progressive muscle weakness. The vast majority of women suffering from muscle diseases develop a deterioration of symptoms during pregnancy. Cardiac and respiratory complications are observed in pregnant women with muscular dystrophy especially in the second and third trimester. The successful perioperative therapy of a 32-year-old pregnant tetraplegic woman with a severe limb-girdle type muscular dystrophy who underwent elective Caesarean section is reported. According to the literature epidural and spinal anesthesia are both possible for perioperative anesthetic management in women with limb-girdle dystrophies. Due to the excellent controllability of intrathecal hyperbaric bupivacaine it was decided to use spinal anesthesia and non-invasive positive pressure ventilation was planned in case of impairment of respiratory function. In summary limb-girdle muscular dysthrophies should be managed on an individual basis and spinal anesthesia can be safely used to avoid intubation.

Successful weaning from extracorporal circulation using a pumpless extracorporal lung assist device in a patient with intraoperative hypercapnic lung failure during aortic valve replacement.

We present a case of a 59-year-old female suffering from massive pulmonary edema with consecutive hypercapnic lung failure immediately following elective aortic valve replacement. Due to severe restrictive ventilation disorder, mechanical ventilation was inadequate. A pumpless lung assist (PECLA, iLA, Novalung®, Talheim, Germany)--a device for extracorporeal carbon dioxide elimination--was used for successful weaning from extracorporeal circulation (ECC). Within 24 hours respiratory function had normalized and the patient could be extubated. The further clinical course and follow-up at 3 months remained uneventful. This report describes the first intraoperative use of the PECLA device in a cardiac surgery patient to promote weaning from ECC.

[Further education in anesthesiology. Implementation at the University Hospital Hamburg-Eppendorf]. / Weiterbildung in der Anästhesiologie. Umsetzung am Universitätsklinikum Hamburg-Eppendorf.

Due to the lack of physicians and the changing demands of junior staff more attractive curricula are needed in anesthesiology in Germany. In the German Society of Anesthesiology and Intensive Care Medicine as well as the Association of German Anesthesiologists discussions on the optimization of training have a long tradition. The following article gives a description of the concept and the practical approach to the training curricular at the University Hospital Hamburg-Eppendorf and is designed to stimulate discussion on possible concepts for training in anesthesiology.

Respiratory systolic variation test in acutely impaired cardiac function for predicting volume responsiveness in pigs.

BACKGROUND: Predicting the response of cardiac output (CO) to volume administration remains difficult, in particular in patients with acutely compromised cardiac function, where, even small amounts of i.v. fluids can lead to volume overload. We compared the ability to predict volume responsiveness of different functional haemodynamic parameters, such as pulse pressure variation (PPV), stroke volume variation (SVV), the static preload parameter right atrial pressure (RAP), and global end-diastolic volume (GEDV) with the recently proposed respiratory systolic variation test (RSVT) in acutely impaired cardiac function. METHODS: In 13 mechanically ventilated pigs, cardiac function was acutely reduced by continuous application of verapamil to reach a decrease in peak change of left ventricular pressure over time (dP/dt) of 50%. After withdrawal of 20 ml kg(-1) BW blood to establish hypovolaemia, four volume loading steps of 7 ml kg(-1) BW using the shed blood and 6% hydroxyethylstarch 130/0.4 were performed. Volume responsiveness was considered as positive, if CO increased more than 10%. RESULTS: Receiver operating characteristic curve analysis revealed an area under the curve (AUC) of 0.88 for the RSVT, 0.84 for PPV, 0.82 for SVV, 0.78 for RAP, and 0.77 for GEDV. CONCLUSIONS: Functional parameters of cardiac preload, including the RSVT, allow prediction of fluid responsiveness in an experimental model of acutely impaired cardiac function.

[Improved survival by guideline compliant cardiopulmonary resuscitation: analysis of primary survival rates in the Hamburg emergency medical service]. / Verbessertes Überleben durch leitliniengerechte kardiopulmonale Reanimation : Analyse der primären Überlebensrate im Hamburger Rettungsdienst.

BACKGROUND: In 2005 revised guidelines for cardiopulmonary resuscitation (CPR) were published by the European Resuscitation Council replacing the guidelines implemented in the year 2000. The aim of this study was to test the compliance with valid guidelines and to establish the quality of pre-hospital CPR provided by paramedics over a period of 38 months. PATIENTS AND METHODS: A total of 299 CPRs performed by paramedics of the emergency medical services of Hamburg, Germany between 1(st) November 2004 and 31(st) December 2007 were analyzed. Digital recordings of automated external defibrillators and emergency protocol data were analyzed in detail. CPR was judged as incorrect if the defibrillation energy level did not correspond to the valid guidelines or if the interval between defibrillations exceeded a tolerance range of more than 30% compared to the valid guidelines. RESULTS: All CPRs (299) were included in the analysis of which 197 (65.9%) were intended to follow the 2000 guidelines and 102 (34.1%) the 2005 guidelines. Return of spontaneous circulation (ROSC) was achieved in 164 cases (54.8%) and survival to hospital admission in 125 cases (41.8%). CPR was performed accurately according to guidelines in only 26 cases (8.7%). In 273 cases (91.3%) the guidelines were not followed completely. Concerning the translation of guidelines into practice most faults occurred due to wrong intervals (89.3%), wrong defibrillation energy (33.4%) and medical errors, such as defibrillating an asystolic patient (7.0%). Primary survival rates were not significantly different when CPR accurately followed the 2000 or 2005 guidelines (40.1% versus 45.1%). Comparing primary survival rates of cases in which the guidelines were followed completely, there was no significant difference between the 2000 guidelines (15 out of 21 cases 71.4%) and 2005 guidelines (4 out of 5 cases 80.0%). However, compliance with valid guidelines significantly increased primary survival rates compared to non-compliance with valid guidelines (19 out of 26 cases 73.1% versus 106 out of 273 cases 38.8%; p=0.007). This effect was independent of the duration of CPR. Comparing CPR with monophasic defibrillation (189 cases) or biphasic defibrillation (58 cases), there was a significantly higher rate of ROSC (56.1% versus 72.4%) and a significantly higher rate of primary survival (41.3% versus 56.9%) in favour of biphasic defibrillation. CONCLUSION: The results of our study show that compliance with valid guidelines is low and furthermore suggest that compliance with guidelines significantly reduces mortality. Future research may be warranted into the question of how to increase compliance with current CPR guidelines in pre-hospital emergency care.

[Co-editors and editors with Jewish origins of the first German journals for anaesthesia. Their fate under National Socialism and an attempt at a biographical appreciation]. / Mitarbeiter und Herausgeber mit jüdischer Herkunft der ersten deutschen Anästhesiezeitschriften. Ihr Schicksal im Nationalsozialismus und der Versuch einer biografischen Würdigung.

The decision to publish the journals Der Schmerz and Narkose und Anaesthesie in 1928 was an important step towards the professionalization of anaesthesiology in Germany. The appearance of both journals, which for economic reasons merged into Schmerz - Narkose - Anaesthesie 1 year later, was initiated and vehemently supported by Jewish physicians. As editors and co-editors they were deeply involved with the editorial tasks of the journals for years from the early beginnings. When the National Socialistic Party took over the government in Germany many of the Jewish colleagues were forced to quit their editorial tasks, were eliminated and replaced by "Arians", they were persecuted and often arrested, forced to emigrate or decided to commit suicide due to inhumane personal circumstances. It is our intention to recall the biography and the terrible fate of the nearly unknown Jewish members of the editorial board of the first German anaesthesia journals. Moreover the biographic sketches promote a continuous discussion about the victims of an inhumane and barbarous ideology.

[General anesthesia in a patient with idiopathic orthostatic hypotension]. / Allgemeinanästhesie bei einem Patienten mit idiopathischer orthostatischer Hypotonie.

Idiopathic orthostatic hypotension (formerly known as Shy-Drager syndrome) is a multiple system atrophy, which is characterized by autonomic dysregulation. Providing perioperative hemodynamic stability during narcosis is therefore a particular challenge. The effects of general anesthesia on systemic vascular resistance and cardiac output in a patient with idiopathic orthostatic hypotension undergoing retropubic prostatectomy will be reported. In the case presented perioperative hemodynamic stability was achieved by aggressive volume therapy guided by global end-diastolic volume measurement and low-dose catecholamine therapy.

[Hemodynamic monitoring in one-lung ventilation]. / Hämodynamisches Monitoring bei Einlungenventilation.

One-lung ventilation causes adverse effects in pulmonary gas exchange and cardiocirculatory function. These adverse effects become particularly important for patients with underlying cardiopulmonary comorbidities. Alterations in pulmonary gas exchange have been investigated in several experimental and clinical trials. However, the hemodynamic consequences of one-lung ventilation are to a great extent unknown. Furthermore, no conclusive recommendations exist as to which kind of hemodynamic monitoring should be preferred in the situation of one-lung ventilation. Many issues regarding hemodynamic monitoring in one-lung ventilation remain unacknowledged. This article will review the current literature on hemodynamic monitoring in one-lung ventilation in order to derive recommendations for the application of hemodynamic monitoring in this specific peri-operative situation.