Laser-direct-drive fusion target design with a high-Z gradient-density pusher shell

Laser-direct-drive fusion target designs with solid deuterium-tritium (DT) fuel, a high-Z gradient-density pusher shell (GDPS), and a Au-coated foam layer have been investigated through both 1D and 2D radiation-hydrodynamic simulations. Compared with conventional low-Z ablators and DT-push-on-DT targets, these GDPS targets possess certain advantages of being instability-resistant implosions that can be high adiabat (α≥8) and low hot-spot and pusher-shell convergence (CR_{hs}≈22 and CR_{PS}≈17), and have a low implosion velocity (v_{imp}<3×10^{7}cm/s). Using symmetric drive with laser energies of 1.9 to 2.5MJ, 1D lilac simulations of these GDPS implosions can result in neutron yields corresponding to ≳50-MJ energy, even with reduced laser absorption due to the cross-beam energy transfer (CBET) effect. Two-dimensional draco simulations show that these GDPS targets can still ignite and deliver neutron yields from 4 to ∼10MJ even if CBET is present, while traditional DT-push-on-DT targets normally fail due to the CBET-induced reduction of ablation pressure. If CBET is mitigated, these GDPS targets are expected to produce neutron yields of >20MJ at a driven laser energy of ∼2MJ. The key factors behind the robust ignition and moderate energy gain of such GDPS implosions are as follows: (1) The high initial density of the high-Z pusher shell can be placed at a very high adiabat while the DT fuel is maintained at a relatively low-entropy state; therefore, such implosions can still provide enough compression ρR>1g/cm^{2} for sufficient confinement; (2) the high-Z layer significantly reduces heat-conduction loss from the hot spot since thermal conductivity scales as ∼1/Z; and (3) possible radiation trapping may offer an additional advantage for reducing energy loss from such high-Z targets.

A neuronal mechanism for motivational control of behavior

Acting to achieve goals depends on the ability to motivate specific behaviors based on their predicted consequences given an individual’s internal state. However, the underlying neuronal mechanisms that encode and maintain such specific motivational control of behavior are poorly understood. Here, we used Ca²⁺ imaging and optogenetic manipulations in the basolateral amygdala of freely moving mice performing noncued, self-paced instrumental goal-directed actions to receive and consume rewards. We found that distinct neuronal activity patterns sequentially represent the entire action-consumption behavioral sequence. Whereas action-associated patterns integrated the identity, value, and expectancy of pursued goals, consumption-associated patterns reflected the identity and value of experienced outcomes. Thus, the interplay between these patterns allows the maintenance of specific motivational states necessary to adaptively direct behavior toward prospective rewards.

[Acute pain therapy in German hospitals as competitive factor. Do competition, ownership and case severity influence the practice of acute pain therapy?]

BACKGROUND

Due to the implementation of the diagnosis-related groups (DRG) system, the competitive pressure on German hospitals increased. In this context it has been shown that acute pain management offers economic benefits for hospitals. The aim of this study was to analyze the impact of the competitive situation, the ownership and the economic resources required on structures and processes for acute pain management.

MATERIAL AND METHODS

A standardized questionnaire on structures and processes of acute pain management was mailed to the 885 directors of German departments of anesthesiology listed as members of the German Society of Anesthesiology and Intensive Care Medicine (DGAI, Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin).

RESULTS

For most hospitals a strong regional competition existed; however, this parameter affected neither the implementation of structures nor the recommended treatment processes for pain therapy. In contrast, a clear preference for hospitals in private ownership to use the benchmarking tool QUIPS (quality improvement in postoperative pain therapy) was found. These hospitals also presented information on coping with the management of pain in the corporate clinic mission statement more often and published information about the quality of acute pain management in the quality reports more frequently. No differences were found between hospitals with different forms of ownership in the implementation of acute pain services, quality circles, expert standard pain management and the implementation of recommended processes. Hospitals with a higher case mix index (CMI) had a certified acute pain management more often. The corporate mission statement of these hospitals also contained information on how to cope with pain, presentation of the quality of pain management in the quality report, implementation of quality circles and the implementation of the expert standard pain management more frequently. There were no differences in the frequency of using the benchmarking tool QUIPS or the implementation of recommended treatment processes with respect to the CMI.

CONCLUSION

In this survey no effect of the competitive situation of hospitals on acute pain management could be demonstrated. Private ownership and a higher CMI were more often associated with structures of acute pain management which were publicly accessible in terms of hospital marketing.

Abstract TP242: Optimization of In-hospital Workflow of Acute Stroke Patients

Introduction: Time from symptom onset to recanalization and especially from admission to recanalization are important factors in the treatment of acute stroke patients with large vessel occlusion.

Hypothesis: Frequent team meetings between neurologists, neuroradiologists and anesthesiologists as well as a new interdisciplinary standard operating procedure (SOP) would lead to a significant reduction of time from admission to recanalization in treating acute stroke patients. A shift to better clinical outcomes would be documented after implementation of the new SOP.

Methods: Data were extracted from a prospectively documented university hospital stroke database. 315 patients were divided into a) 242 patients treated with mechanical thrombectomy prior to the new SOP from 2007 until 2013 and b) 73 patients treated with mechanical thrombectomy after implementation of the new SOP from 2014 to now.

Results: Symptom onset to admission time was not statistically significant between the two groups. Time from admission to groin puncture was massively reduced from 120 to 65 minutes after implementation of the new SOP (P < 0,0001). Groin to recanalization time was also significantly reduced (P=0,0011). The use of a stent retriever was not a significant factor in reducing times from groin puncture to recanalization. Implementation of the new SOP led to a significant shift of clinical outcomes after mechanical thrombectomy.

Conclusions: Interdisciplinary team work and implementation of a new SOP led to a significant reduction of in-hospital examination, transportation, imaging and treatment times in our stroke center. Better clinical outcomes were reported with faster treatment times.

Midterm results after arterial switch operation for transposition of the great arteries: a single centre experience

Background

The arterial switch operation (ASO) has become the surgical approach of choice for d-transposition of the great arteries (d-TGA). There is, however an increased incidence of midterm and longterm adverse sequelae in some survivors. In order to evaluate operative risk and midterm outcome in this population, we reviewed patients who underwent ASO for TGA at our centre.

Methods

In this retrospective study 52 consecutive patients with TGA who underwent ASO between 04/1991 and 12/1999 were included. To analyze the predictors for mortality and adverse events (coronary stenoses, distortion of the pulmonary arteries, dilatation of the neoaortic root, and aortic regurgitation), a multivariate analysis was performed. The follow-up time was ranged from 1–10 years (mean 5 years, cumulative 260 patient-years).

Results

All over mortality rate was 15.4% and was only observed in the early postoperative period till 1994. The predictors for poor operative survival were low APGAR-score, older age at surgery, and necessity of associated surgical procedures. Late re-operations were necessary in 6 patients (13.6%) and included a pulmonary artery patch enlargement due to supravalvular stenosis (n = 3), coronary revascularisation due to coronary stenosis in a coronary anatomy type E, aortic valve replacement due to neoaortic valve regurgitation (n = 2), and patch-plasty of a pulmonary vein due to obstruction (n = 1). The dilatation of neoaortic root was not observed in the follow up.

Conclusions

ASO remains the procedure of choice for TGA with acceptable early and late outcome in terms of overall survival and freedom of reoperation. Although ASO is often complex and may be associated with morbidity, most patients survived without major complications even in a small centre.

Hemodynamic effects of peri-operative statin therapy in on-pump cardiac surgery patients

Background

Peri-operative statin therapy in cardiac surgery cases is reported to reduce the rate of mortality, stroke, postoperative atrial fibrillation, and systemic inflammation. Systemic inflammation could affect the hemodynamic parameters and stability. We set out to study the effect of statin therapy on perioperative hemodynamic parameters and its clinical outcome.

Methods

In a single center study from 2006 to 2007, peri-operative hemodynamic parameters of 478 patients, who underwent cardiac surgery with cardiopulmonary bypass, were measured. Patients were divided into those who received perioperative statin therapy (n = 276; statin group) and those who did not receive statin therapy (n = 202; no-statin group). The two groups were compared together using Kolmogorov-Smirnov-Test, Fisher’s-Exact-Test, and Student’s-T-test. A p value < 0.05 was considered as significant.

Results

There was no significant difference in the preoperative risk factors. Onset of postoperative atrial fibrillation was not affected by statin therapy. Extended hemodynamic measurements revealed no significant difference between the two groups, apart from Systemic Vascular Resistance Index (SVRI) . The no-statin group had a significantly higher SVRI (882 ± 206 vs. 1050 ± 501 dyn s/cm⁵/m², p = 0.022). Inotropic support was the same in both groups and no significant difference in the mortality rate was noticed. Also, hemodynamic parameters were not affected by different types and doses of statins.

Conclusions

Perioperative statin therapy for patients undergoing on-pump coronary bypass grafting or valvular surgery, does not affect the hemodynamic parameters and its clinical outcome.

Cost analysis of two anaesthetic machines: "Primus®" and "Zeus®"

Background

Two anaesthetic machines, the "Primus^®" and the "Zeus^®" (Draeger AG, Lübeck, Germany), were subjected to a cost analysis by evaluating the various expenses that go into using each machine.

Methods

These expenses included the acquisition, maintenance, training and device-specific accessory costs. In addition, oxygen, medical air and volatile anaesthetic consumption were determined for each machine.

Results

Anaesthesia duration was 278 ± 140 and 208 ± 112 minutes in the Primus^® and the Zeus^®, respectively. The purchase cost was €3.28 and €4.58 per hour of operation in the Primus^® and the Zeus^®, respectively. The maintenance cost was €0.90 and €1.20 per hour of operation in the Primus^® and the Zeus^®, respectively. We found that the O₂ cost was €0.015 ± 0.013 and €0.056 ± 0.121 per hour of operation in the Primus^® and the Zeus^®, respectively. The medical air cost was €0.005 ± 0.003 and €0.016 ± 0.027 per hour of operation in the Primus^® and the Zeus^®, respectively. The volatile anaesthetic cost was €2.40 ± 2.40 and €4.80 ± 4.80 per hour of operation in the Primus^® and the Zeus^®, respectively.

Conclusion

This study showed that the "Zeus^®" generates a higher cost per hour of operation compared to the "Primus®".

Treatment of gram-positive deep sternal wound infections in cardiac surgery--experiences with daptomycin

The reported incidence of deep sternal wound infection (DSWI) after cardiac surgery is 0.4-5% with Staphylococcus aureus being the most common pathogen isolated from infected wound sternotomies and bacteraemic blood cultures. This infection is associated with a higher morbidity and mortality than other known aetiologies. Little is reported about the optimal antibiotic management. The aim of the study is to quantify the application of daptomycin treatment of DSWI due to gram-positive organisms post cardiac surgery. We performed an observational analysis in 23 cases of post sternotomy DSWI with gram-positive organisms February 2009 and September 2010. When the wound appeared viable and the microbiological cultures were negative, the technique of chest closure was individualised to the patient. The incidence of DSWI was 1.46%. The mean dose of daptomycin application was 4.4 ± 0.9 mg/kg/d and the average duration of the daptomycin application was 14.47 ± 7.33 days. In 89% of the patients VAC therapy was used. The duration from daptomycin application to sternal closure was 18 ± 13.9 days. The parameters of infection including, fibrinogen (p = 0.03), white blood cell count (p = 0.001) and C-reactive protein (p = 0.0001) were significantly reduced after daptomycin application. We had no mortality and wound healing was successfully achieved in all patients. Treatment of DSWI due to gram-positive organisms with a daptomycin-containing antibiotic regimen is safe, effective and promotes immediate improvement of local wound conditions.Based on these observations, daptomycin may offer a new treatment option for expediting surgical management of DSWI after cardiac surgery.

Recurrent strokes under anticoagulation therapy: Sticky platelet syndrome combined with a patent foramen ovale

The sticky platelet syndrome (SPS) is a congenital disorder characterized by platelet hyperaggregability to epinephrine and/or adenosine diphosphate; this predisposes affected individuals to acute myocardial infarction, ischemic optic neuropathy, recurrent venous thromboembolism, and transient ischemic cerebral attacks and strokes. Here, we describe an unusual case with recurrent cerebrovascular accidents due to SPS, in the presence of a patent foramen ovale (PFO). We report an unusual case of a 56-year-old female patient with a PFO, who suffered from recurrent strokes despite long-term medication with clopidogrel for SPS. The patient underwent successful transcatheter closure of the PFO, and, in addition, she has been placed on low-dose acetylsalicylic acid. After 18-month follow-up, she demonstrated an intact atrial septum without any vegetations on the percutaneous device until today. She has had no further thromboembolic events.

[Preoperative prewarming as a routine measure. First experiences]

BACKGROUND

Despite the broad application of intraoperative warming new studies still show a high incidence of perioperative hypothermia. Therefore a prewarming program in the preoperative holding area was started.

METHODS

The efficacy of the prewarming program was assessed with an accompanying quality assurance check sheet over a period of 3 months.

RESULTS

During the 3 month test period 127 patients were included. The median length from arrival in the holding area to beginning prewarming was 6 min and the average duration of prewarming was 46±38 min. During prewarming the core temperature rose by 0.3±0.4°C to 37.1±0.5°C and decreased to 36.3±0.5°C after induction of anesthesia. At the end of the operation the core temperature was 36.4±0.5°C and 14% of the patients were hypothermic.

CONCLUSION

These data allow 2 conclusions: 1. Prewarming in the holding area is possible with a sufficient duration. 2. Prewarming is highly efficient even when performed over a relatively short duration.

CABG surgery with long coronary endarterectomy of the LAD

Diffuse atherosclerosis of the anterior descending artery may require unconventional surgical treatment to increase graft flow. A 74-year-old man with severe, diffuse 3-vessel-coronary artery disease was presented to our institution with progredient angina pectoris symptoms. Intraoperatively, the revascularization of the left anterior descending coronary artery (LAD) was technically challenging because of the extremely calcified coronary artery disease; therefore we performed the longest endarterectomy of the LAD that has thus far been described.

Extracorporeal life support in pediatric cardiac dysfunction

BACKGROUND

Low cardiac output (LCO) after corrective surgery remains a serious complication in pediatric congenital heart diseases (CHD). In the case of refractory LCO, extra corporeal life support (ECLS) extra corporeal membrane oxygenation (ECMO) or ventricle assist devices (VAD) is the final therapeutic option. In the present study we have reviewed the outcomes of pediatric patients after corrective surgery necessitating ECLS and compared outcomes with pediatric patients necessitating ECLS because of dilatated cardiomyopathy (DCM).

METHODS

A retrospective single-centre cohort study was evaluated in pediatric patients, between 1991 and 2008, that required ECLS. A total of 48 patients received ECLS, of which 23 were male and 25 female. The indications for ECLS included CHD in 32 patients and DCM in 16 patients.

RESULTS

The mean age was 1.2 ± 3.9 years for CHD patients and 10.4 ± 5.8 years for DCM patients. Twenty-six patients received ECMO and 22 patients received VAD. A total of 15 patients out of 48 survived, 8 were discharged after myocardial recovery and 7 were discharged after successful heart transplantation. The overall mortality in patients with extracorporeal life support was 68%.

CONCLUSION

Although the use of ECLS shows a significantly high mortality rate it remains the ultimate chance for children. For better results, ECLS should be initiated in the operating room or shortly thereafter. Bridge to heart transplantation should be considered if there is no improvement in cardiac function to avoid irreversible multiorgan failure (MFO).

AMPK - Activated Protein Kinase and its Role in Energy Metabolism of the Heart

Adenosine monophosphate - activated kinase (AMPK) plays a key role in the coordination of the heart's anabolic and catabolic pathways. It induces a cellular cascade at the center of maintaining energy homeostasis in the cardiomyocytes.. The activated AMPK is a heterotrimeric protein, separated into a catalytic α - subunit (63kDa), a regulating β - subunit (38kDa) and a γ - subunit (38kDa), which is allosterically adjusted by adenosine triphosphate (ATP) and adenosine monophosphate (AMP). The actual binding of AMP to the γ - subunit is the step which activates AMPK. AMPK serves also as a protein kinase in several metabolic pathways of the heart, including cellular energy sensoring or cardiovascular protection. The AMPK cascade represents a sensitive system, activated by cellular stresses that deplete ATP and acts as an indicator of intracellular ATP/AMP. In the context of cellular stressors (i.e. hypoxia, pressure overload, hypertrophy or ATP deficiency) the increasing levels of AMP promote allosteric activation and phosphorylation of AMPK. As the concentration of AMP begins to increase, ATP competitively inhibits further phosphorylation of AMPK. The increase of AMP may also be induced either from an iatrogenic emboli, percutaneous coronary intervention, or from atherosclerotic plaque rupture leading to an ischemia in the microcirculation. To modulate energy metabolism by phosphorylation and dephosphorylation is vital in terms of ATP usage, maintaining transmembrane transporters and preserving membrane potential. In this article, we review AMPK and its role as an important regulatory enzyme during periods of myocardial stress, regulating energy metabolism, protein synthesis and cardiovascular protection.

Aortic valve surgery in congenital heart disease: a single-center experience

The optimal treatment of congenital aortic valve lesions is a controversial issue. This study was performed to evaluate the outcome after surgical treatment of aortic valve lesions in congenital aortic valve disease. Between the years of 2000 and 2008, 61 patients (mean age: 12.6 +/- 9.6 years, range: 1 day to 40 years) underwent aortic valve surgery for congenital aortic valve disease. Twenty-four patients had undergone previous cardiovascular operations. Indications for surgery were aortic regurgitation in 14.7% (n = 9), aortic stenoses in 26.2% (n = 16), and mixed disease in 59.1% (n = 36). The Ross procedure was performed in 37.7% (n = 23), aortic valve replacement with biological or mechanical prostheses in 29.5% (n = 18). Concomitant procedures were performed in 91.8% (n = 56) due to associated congenital cardiac defects. The overall mortality rate was 5%. Six patients needed reoperation. Implantation of permanent pacemakers occurred in six patients for permanent atrioventricular block. At the latest clinical evaluation, all survivors are in New York Heart Association class I-II and are living normal lives. Aortic valve surgeries in patients with congenital heart disease have had low mortality and morbidity rates in our series. Surgical technique as well as timing should be tailored for each patient. Aortic valve replacement should be delayed until the implantation of an adult-sized prosthesis is possible.

Extracorporeal life support in pediatric patients with congenital heart diseases: outcome of a single centre

AIM

In pediatric patients with congenital heart disease low cardiac output (LCO) is the principal complication after corrective heart surgery. In LCO refractory to all therapeutic options, mechanical circulatory support is the final method to keep these patients alive. In this present study the authors reviewed the outcome of pediatric patients who required mechanical circulatory support after corrective surgery with extracorporeal membrane oxygenation or ventricle assisted devices (VAD).

METHODS

A retrospective single centre consecutive cohort study was carried out in children who required different mechanical circulatory support indicated by postcardiotomy low output syndrome between 1991 and 2004. A total of 20 patients received extracorporeal life support. The indications for surgery were: 12 transposition of great arteries, 1 Bland-White-Garland syndrome, 3 tetralogy of Fallot, 1 hypoplasia of aortic arch, 1 total anomalous pulmonary vein connection, and 2 ventricle septum defect.

RESULTS

Mean age was 1.29 years. Mean duration of assist was 8.87 days. Seven patients out of 20 survived, six could be discharged after myocardial recovery from LCO and one could be discharged after successful heart transplantation. The overall mortality in patients with extracorporeal life support was 65%. The causes of death were multiorgan failure and bleeding in one case was a VAD related complication.

CONCLUSION

The use of extracorporeal life support (ECLS) shows a high mortality rate. However, ECLS can still help to keep some of those patients alive. Mechanical support devices are the ultimate chance to save time, to increase survival and to bridge the time until heart transplantation.

Clinical relevance of eNOS T-786C polymorphism for hospital mortality and morbidity in cardiac surgical patients

AIM

The endothelial nitric oxide (eNOS) gene T-786C polymorphism may influence as a genetic risk factor cardiovascular diseases and shows association with cardiovascular mortality. We hypothesized that this polymorphism may lead to increase mortality and morbidity after cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

In 500 patients who underwent cardiac surgery with CPB we investigated the eNOS T-786C polymorphism by DNA-sequencing. The patients were grouped according to their genotype in three groups (TT, TC, and CC).

RESULTS

The overall genotype distribution of T-786C polymorphism was TT=41.6%, TC=51.2%, and CC=7.2% respectively. The groups did not differ in age and gender. No significance was shown in preoperative risk factors, excluding peripheral disease (P=0.03). No difference was shown in Euroscore, APACHE II, and SAPS II. The usage of norepinephrine (P=0.03) and nitroglycerine (P=0.01) was significant higher in TC allele carrier. The mortality was quite uniform across elective and urgent subgroup. However, we found a significant difference concerning mortality and emergency cardiac procedures in homozygous C-allele carrier (P=0.014).

CONCLUSION

The present study demonstrates that this polymorphism contributes to a higher prevalence of postoperative mortality after emergency cardiac surgery. Thus, the eNOS T-786C polymorphism could serve as a possibility to differentiate high risk subgroups in heterogeneous population of individuals with cardiac diseases who need cardiac surgery with CPB.

Surgical treatment of left ventricular aneurysm

When a left ventricular aneurysm leads to pulmonary congestive symptoms, aneurysmectomy may provide relief. This retrospective study included 269 patients who underwent aneurysmectomy between 1993 and 2002, by the classic Cooley operation in 164 and by Dor ventriculoplasty in 105. There were no significant differences in early and late survival between groups, although the frequency of extended anteroseptal infarction was higher in patients undergoing the Dor procedure. Postoperative echocardiographic findings showed significant improvements in left ventricular function in both groups, in terms of end-diastolic and end-systolic dimensions and ejection fraction. Left ventricular aneurysmectomy significantly improved the clinical status and hemodynamic parameters of symptomatic patients. The choice of surgical technique depends on the extent of the scar segment, especially the presence of an anteroseptal scarred area. The Dor procedure is more suitable for restoring normal left ventricular geometry in patients with extensive septal infarction.

Experiences with surgical treatment of ventricle septal defect as a post infarction complication

BACKGROUND

Complications of acute myocardial infarction (AMI) with mechanical defects are associated with poor prognosis. Surgical intervention is indicated for a majority of these patients. The goal of surgical intervention is to improve the systolic cardiac function and to achieve a hemodynamic stability. In this present study we reviewed the outcome of patients with post infarction ventricular septal defect (PVSD) who underwent cardiac surgery.

METHODS

We analysed retrospectively the hospital records of 41 patients, whose ages range from 48 to 81, and underwent a surgical treatment between 1990 and 2005 because of PVSD.

RESULTS

In 22 patients concomitant coronary artery bypass grafting (CAGB) was performed. In 15 patients a residual shunt was found, this required re-op in seven of them. The time interval from infarct to rupture was 8.7 days and from rupture to surgery was 23.1 days. Hospital mortality in PVSD group was 32%. The mortality of urgent repair within 3 days of intractable cardiogenic shock was 100%. The mortality of patients with an anterior VSD and a posterior VSD was 29.6% vs 42.8%, respectively. All patients who underwent the surgical repair later than day 36 survived.

CONCLUSION

Surgical intervention is indicated for a majority of patients with mechanical complications. Cardiogenic shock remains the most important factor that affects the early results. The surgical repair of PVSD should be performed 4-5 weeks after AMI. To improve surgical outcome and hemodynamics the choice of surgical technique and surgical timing as well as preoperative management should be tailored for each patient individually.

Acute aortic dissection type A discloses Corpus alienum

We report an unusual case of an aortic type A dissection with a corpus alienum which compresses the right ventricle. The patient successfully underwent an aortic root replacement in deep hypothermia with re-implantation of the coronary arteries using a modified Bentall procedure and the resection of the corpus alienum. Intraoperative finding reveals 3 greatly adhered gauze compresses, which were most likely forgotten in the operation 34 years ago.

Accelerated intimal hyperplasia in aortocoronary internal mammary vein grafts in minipigs

Background

More than 50% of aortocoronary saphenous vein grafts are occluded 10 years after surgery. Intimal hyperplasia is the initial critical step in the progression toward occlusion. Internal mammary veins, which are physiologically prone to less hydrostatic pressure, may undergo an accelerated progression to intimal hyperplasia and thus be suitable for investigation of the mechanisms of aortocoronary vein graft disease.

Methods

Six minipigs underwent aortocoronary bypass grafting using standard cardiopulmonary bypass and cardioplegic arrest. Mammary vein were grafted in a reversed manner from ascending aorta to left anterior descending coronary artery (LAD). The proximal LAD was ligated, rendering the anterior left ventricle vein graft-dependent. Minipigs were killed after 4 weeks, and vein grafts were harvested. Histological and immunohistological investigation were performed with respect to morphometric analysis, endothelial damage/dysfunction (v-Willebrand-factor (vWF)), smooth muscle cells (α-smooth actin) and proliferation rate (proliferation marker Ki 67).

Results

Mean intimal area of vein grafts was increased compared to ungrafted mammary veins. Intimal hyperplasia in vein grafts was characterized by massive accumulation of smooth muscle cells with a high proliferation rate and endothelial perturbation. Significant (p = 0.001) intimal hyperplasia of the grafted mammary vein compared to the ungrafted mammary vein was found. These changes were absent in ungrafted mammary veins.

Conclusion

The present study demonstrates a pig model of aortocoronary vein graft intimal hyperplasia which is characterized by an accelerated progression within internal mammary veins. The model is suitable to investigate the pathophysiology of aortocoronary vein graft intimal hyperplasia as well as therapeutic approaches.

Influence of angiotensin-I-converting-enzyme insertion/deletion gene polymorphism on perioperative hemodynamics after coronary bypass graft surgery

AIM

The angiotensin I-converting enzyme insertion/ deletion polymorphism (ACE-I/D), including three genotypes (II, ID, DD), with a known impact on midterm mortality and morbidity in patients after coronary artery bypass graft surgery (CABG), was studied. Since this polymorphism has been linked with increased vascular response to phenylephrine during cardiopulmonary bypass (CPB), we investigated its possible effect on perioperative hemodynamics in patients undergoing CABG.

METHODS

Genotyping for the ACE-I/D was performed by polymerase chain reaction (PRC) amplification in 110 patients who underwent elective CABG with CPB. Patients were assigned to two groups according to their genotype (group II [II genotype] and group ID/DD [ID and DD genotypes]). Systemic hemodynamics were measured directly before and at 4 h, 9 h, and 19 h after CPB.

RESULTS

Genotype distribution of ACE-I/D was 18%, 57%, and 25% in genotypes II, ID, and DD, respectively. The two groups were similar in age (group II: 66+/-6 years, group ID/DD: 66+/-8 years), body-mass-index (BMI) (group II: 28+/-2, group ID/DD: 29+/-5 kg/m2), male: female ratio (group II: 16: 4, group ID/DD: 63: 27) and Euroscore (group II: 3.1+/-1.9, group ID/DD: 3.5+/-2.1). There were no differences in mortality rate or perioperative systemic hemodynamics. The pulmonary vascular resistance before cardiopulmonary bypass was higher in the ID/DD genotypes than in the II genotypes (227+/-121 vs 297+/-169 dyn.s(-1).m2.cm(-5)). Four hours after CPB no difference remained; at 9 h after cardiopulmonary bypass there was a slight difference in pulmonary vascular resistance between the two groups (247+/-134 vs 290+/-117 dyn.s(-1).m2.cm(-5)) and a significant difference in pulmonary arterial pressure (19+/-6 vs 23+/-8); at 19 h after CPB the differences were no longer detectable.

CONCLUSION

ACE-I/D had no influence on perioperative systemic hemodynamics. However, transitory differences in pulmonary hemodynamic were observed after CPB. These differences may have been due to changes in serum ACE activity during CPB.

[Electrical impedance tomography: ready for routine clinical use for mechanically ventilated patients?]

Electrical impedance tomography (EIT) is a non-invasive, radiation-free functional imaging technique, which offers the possibility of continuous bedside measurement of regional lung ventilation. The principle of EIT is based on the input of alternating current and voltage measurement via surface electrodes placed around the thorax, which measure changes of electrical impedance parallel to changes in aeration within the lungs. This enables the measurement of regional ventilation. Because of the rapid time resolution of this technique, it can be used for the measurement of fast physiological effects. For more than 20 years EIT has been intensively used for research purposes, but has not yet been used for the monitoring of regional lung function in the routine clinical setting. This review describes the status of EIT in the clinical routine, its possibilities and limitations.

Regional filling characteristics of the lungs in mechanically ventilated patients with acute lung injury

OBJECTIVES

The objective of the study was to determine regional pulmonary filling characteristics in 20 mechanically ventilated patients with acute lung injury.

METHODS

Regional filling characteristics were calculated from tracings of regional tidal volumes vs. global tidal volumes measured by electrical impedance tomography (EIT). These plots were fitted to a polynomial function of the second degree. Regional polynomial coefficients of the second degree characterized the curve linearity of the plots. Near-zero values of the polynomial coefficient indicated a homogeneous increase in regional tidal volumes during the whole inspiration. Positive values hinted at initial low regional tidal volume change suggesting lung volume recruitment. Negative values indicated late low regional tidal volume change implying hyperinflation of this lung region.

RESULTS

We found a broad heterogeneity of regional lung filling characteristics. The minimal regional polynomial coefficients varied from -2.80 to -0.56 (median -1.16), while the maximal regional polynomial coefficients varied from 0.58 to 3.65 (median 1.41).

CONCLUSIONS

Measurements of regional filling characteristics by EIT may be a helpful tool to adjust the respiratory settings during mechanical ventilation to optimize lung recruitment and to avoid overdistension. It applies a non-pressure-related assessment to the mechanics of lung inflation and gives a view of the real problems underlying ventilatory strategies dependent on global characteristics.

CMV monitoring using blood cells and plasma: a comparison of apples with oranges?

Quantitative cytomegalovirus (CMV) monitoring is still far from being standardized between transplant centers. In the present study, we compared assays for quantitative CMV monitoring using blood cells and plasma. Four hundred and thirty-five consecutive samples from 29 patients with active CMV infection after allogeneic T-cell-depleted hemopoietic stem cell transplantation were tested in parallel using pp65 antigenemia and quantitative CMV polymerase chain reaction (PCR) in blood cells and plasma (COBAS AMPLICOR CMV MONITOR). Although only 142 (53.1%) of 253 positive samples were concordantly identified by all three assays, the number of positive samples detected by each assay was not different and the quantitative values were correlated, provided that nucleic acid (NA) in plasma was isolated by COBAS AmpliPrep and not by the manual protocol. Six (18%) of 34 episodes with active CMV infection were not detected using CMV PCR in plasma; whereas in times of white blood cell aplasia or blast crisis of leukemia, samples with active CMV infection in plasma could not be detected using blood cells. We conclude that CMV monitoring in whole blood could be favorable compared with assays using plasma or blood cells alone. Automated NA isolation could become an attractive tool for a more sensitive and better standardized molecular diagnostics.

Imaging pathologic pulmonary air and fluid accumulation by functional and absolute EIT

The increasing use of EIT in clinical research on severely ill lung patients requires a clarification of the influence of pathologic impedance distributions on the validity of the resulting tomograms. Significant accumulation of low-conducting air (e.g. pneumothorax or emphysema) or well-conducting liquid (e.g. haematothorax or atelectases) may conflict with treating the imaging problem as purely linear. First, we investigated the influence of stepwise inflation and deflation by up to 300 ml of air and 300 ml of Ringer solution into the pleural space of five pigs on the resulting tomograms during ventilation at constant tidal volume. Series of EIT images representing relative impedance changes were generated on the basis of a modified Sheffield back projection algorithm and ventilation distribution was displayed as functional (f-EIT) tomograms. In addition, a modified simultaneous iterative reconstruction technique (SIRT) was applied to quantify the resistivity distribution on an absolute level scaled in Omega m (a-EIT). Second, we applied these two EIT techniques on four intensive care patients with inhomogeneous air and fluid distribution and compared the EIT results to computed tomography (CT) and to a reference set of intrathoracic resistivity data of 20 healthy volunteers calculated by SIRT. The results of the animal model show that f-EIT based on back projection is not disturbed by the artificial pneumo- or haematothorax. Application of SIRT allows reliable discrimination and detection of the location and amplitude of pneumo- or haematothorax. These results were supported by the good agreement between the electrical impedance tomograms and CT scans on patients and by the significant differences of regional resistivity data between patients and healthy volunteers.

Outcome of cardiopulmonary resuscitation in the intensive care units of a university hospital

The purpose of this study is to evaluate the demographic characteristics of patients who suffered cardiac arrest in our ICUs and to identify those factors influencing outcome after resuscitation following cardiac arrest. We reviewed the records of all patients who underwent CPR in the two ICUs at the Georg-August University Hospital Goettingen, Germany from 1 January, 1999 to 31 December, 2003. During the study period 169 patients underwent CPR and 80 of the 169 patients survived to hospital discharge, giving a survival to hospital discharge rate of 47.3%. The initial monitored rhythm recorded at the time of arrest was asystole in 99 (58.6%) patients, ventricular tachycardia/fibrillation in 59 (34.9%) and pulseless electrical activity in 7 (4.1%) patients. The respective survival rates were 46 (54.8%), 31 (36.9%) and 5 (6.0%) to hospital discharge. Of the 80 patients that survived to hospital discharge 75 (93.8%) achieved good cerebral recovery (CPC 1 or 2) and were alert and fully oriented on discharge; 4 patients (5.0%) were severely disabled (CPC 3), while 1 (1.2%) remained unconscious and was reported dead five days after discharged to another local hospital. Illness severity as assessed by SAPS II score on admission was 38.8 +/- 16.0. None of our patients with > 40 SAPS II score 24 hours after CPR survived to be discharged from the ICU. Our study showed that nearly half the patients that had cardiac arrest in our hospital ICUs had a favourable outcome despite initial rhythms that are traditionally associated with a poor outcome. This confirms that good results are achievable in these groups of patients.

Regional pulmonary pressure volume curves in mechanically ventilated patients with acute respiratory failure measured by electrical impedance tomography

BACKGROUND

We hypothesized, that in mechanically ventilated patients with acute respiratory failure, regional pressure volume curves differ markedly from conventional global pressure volume curves of the whole lung.

METHODS

In nine mechanically ventilated patients with acute respiratory failure during an inspiratory low-flow manoeuvre, conventional global pressure volume curves were registered by spirometry and regional pressure volume curves in up to 912 regions were assessed simultaneously using electrical impedance tomography. We compared the lower (LIP) and upper (UIP) inflection points obtained from the conventional global pressure volume curve and regional pressure volume curves.

RESULTS

We identified from the conventional global pressure volume curves LIP [3-11 (8) cmH2O] in eight patients and UIP [31-39 (33) cmH2O] in three patients. Using electrical impedance tomography (EIT), LIP [3-18 (8) cmH2O] in 54-264 (180) regions and UIP [23-42 (36) cmH2O] in 149-324 (193) regions (range and median) were identified. Lung mechanics measured by conventional global pressure volume curves are similar to the median of regional pressure volume curves obtained by EIT within the tomographic plane. However, single regional pressure volume curves differ markedly with a broad heterogeneity of lower and upper inflection points.

CONCLUSION

Lower and upper inflection points obtained from conventional global pressure volume curves are not representative of all regions of the lungs.

Assessment of diaphragmatic function with cervical magnetic stimulation in critically ill patients

The objective of this study was to evaluate a non-volitional measurement to assess diaphragmatic function in intubated and mechanically ventilated patients in a prospective pilot interventional clinical trial. The study was conducted in an 18-bed postoperative intensive care unit based at a university hospital. Patients were prospectively assigned to two groups. Group 1 consisted of eight patients with ventilator weaning failure. Group 2 consisted of eight intubated and ventilated patients who were studied shortly after major surgery and were successfully extubated there-after The twitch pressure response after cervical magnetic stimulation of the phrenic nerves was measured at the endotracheal tube at different PEEP levels. In group 2 the twitch transdiaphragmatic pressure, defined as the difference between twitch gastric and twitch oesophageal pressure was also evaluated. In group 1 the mean twitch pressure at the endotracheal tube on PEEP 0, 5 and 10 cmH2O was 5.2, 4.5 and 2.6 cmH2O: In group 2 this was significantly higher (15.1 cmH2O on PEEP 0 and 12.2 cmH2O on PEEP 5). A good correlation was found between twitch diaphragmatic pressure and twitch pressure at the endotracheal tube (r2 = 0.96) and between twitch oesophageal pressure and twitch pressure at the endotracheal tube (r2 = 0.98). Patients with weaning failure have significantly lower twitch pressure at the endotracheal tube suggesting diaphragmatic dysfunction. Twitch pressure at the endotracheal tube may be a useful parameter to screen for diaphragmatic dysfunction in intubated critically ill patients. Further studies are needed to confirm these preliminary findings.

Hemodynamic effects of spontaneous breathing in the post-operative period

BACKGROUND

During mechanical ventilatory support, spontaneous breathing has been linked to improved hemodynamics. These findings may be explained by a decrease in intrathoracic pressure which may improve venous return to the heart. Such a mechanism should result in a dose-response relation between the amount of spontaneous breathing and an increase in the global end-diastolic volume (GEDV) and cardiac output (Q(t)).

METHODS

To test this hypothesis, 15 patients were studied after major elective surgery during weaning from mechanical ventilation using bilevel positive airway pressure (BIPAP). BIPAP allows unrestricted spontaneous breathing during every phase of the respiratory cycle. Thus, ventilatory support was modified by changing the mechanical respiratory rate only, whereas inspiratory airway pressure and PEEP were kept constant. GEDV and Q(t) were measured by transpulmonary thermodilution.

RESULTS

GEDV (P = 0.055), stroke volume (P = 0.027) and subsequently also Q(t) (P < 0.001) increased when spontaneous breathing increased. In contrast, no difference was observed for central venous pressure (P = 0.19).

CONCLUSION

The beneficial hemodynamic effects of spontaneous breathing during mechanical ventilatory support can partially be explained by improved venous return to the heart which increases stroke volume and Q(t).

Effect of positive end-expiratory-pressure on regional ventilation in patients with acute lung injury evaluated by electrical impedance tomography

BACKGROUND AND OBJECTIVE

For the treatment of patients with adult respiratory distress syndrome and acute lung injury bedside measurements of regional lung ventilation should be considered for optimizing ventilatory settings. The aim was to investigate the effect of positive end-expiratory pressure (PEEP) on regional ventilation in mechanically ventilated patients at the bedside by electrical impedance tomography.

METHODS

Eight mechanically ventilated patients were included in the study. PEEP levels were increased from 0 to 5, 10, 15 mbar and back to 0 mbar. Regional ventilation in 912 regions of the thorax was investigated at each PEEP by electrical impedance tomography. The obtained regions were divided in four groups: none (none and poorly ventilated regions including chest wall and mediastinum), bad, moderate and well-ventilated regions.

RESULTS

Increasing the PEEP stepwise from 0 to 15 mbar decreased the non-ventilated regions (none: 540 regions at PEEP 0 and 406 regions at PEEP 15). In contrast, the other regions increased (bad: 316 regions at PEEP 0 and 380 regions at PEEP 15; moderate: 40 regions at PEEP 0 and 100 regions at PEEP 15; well: 0 region at PEEP 0 and 34 regions at PEEP 15 (median values)) indicating an improvement of regional ventilation.

CONCLUSIONS

Increasing PEEP in mechanically ventilated patients reduces none ventilated regions (atelectasis). Furthermore, it leads to a shift from none and bad ventilated regions to moderately and well-ventilated regions. Electrical impedance tomography is a bedside technique and might be an alternative to computed tomography scan to assess aerated lung regions.

Rekrutierungsmanöver bei Patienten mit Lungenversagen

Recruitment maneuvers have been proposed as an adjunct to mechanical ventilation to re-expand collapsed lung regions. Although, in most patients recruitment maneuvers improve gas exchange a controversial discussion on recruitment maneuvers remains. This article reviews the physiological and patho-physiological backgrounds of recruitment maneuvers. The different recruitment maneuvers and possible monitoring are discussed as well as the influence of recruitment on other organs. Furthermore, we discuss whether recruitment maneuvers are useful if patients with acute lung injury or acute respiratory distress syndrome are ventilated with a lung-protective strategy.

Effects of mivacurium on the diaphragm evaluated by cervical magnetic stimulation of the phrenic nerves

BACKGROUND AND OBJECTIVE

Non-depolarizing neuromuscular blocking agents have differential effects on the diaphragm and skeletal muscles. We employed a new method to study the effects of mivacurium on the diaphragm and compared the results obtained with this method with published data.

METHODS

Anaesthesia was induced and maintained with propofol and alfentanil and the trachea was intubated after topical anaesthesia. Contractions of the diaphragm were induced by cervical magnetic stimulation of the phrenic nerves and quantified by measuring airway pressure responses. The neuromuscular effects on skeletal muscles were measured by acceleromyography of the adductor pollicis muscle. Mivacurium (0.15 mg kg(-1)) was injected and neuromuscular responses were recorded until the effects had waned.

RESULTS

Eleven male and 10 female patients (ASA I-II; 57 +/- 16 yr; 78 +/- 13 kg; mean +/- standard deviation) participated. Median maximal reduction of twitch response was less (P < 0.05) for the diaphragm (89%) than for the adductor pollicis (100%). Time to 25% recovery was shorter for the diaphragm than for the adductor pollicis (8.8 +/- 2.2 min vs. 22.6 +/- 5.0 min, P < 0.05). The difference between the recovery index of the diaphragm (7.3 min (3.6-18.4)) and the adductor pollicis (8.2 min (4.4-20.9) (median (range)) just missed our chosen level of statistical significance (P = 0.06). The recovery time to train-of-four 0.8 was shorter for the diaphragm (median and 95% confidence interval 25.1 +/- 10.2 min) than for the adductor pollicis (median and 95% confidence interval 37.5 +/- 9.4 min, P < 0.05).

CONCLUSIONS

The duration of the clinical effect of mivacurium on the diaphragm is markedly shorter than on the adductor pollicis muscles but there was only a small difference in the recovery index of the two muscles. These effects and the time courses determined with the new method closely resemble the results obtained with different methods in other studies.

Spontaneous breathing affects the spatial ventilation and perfusion distribution during mechanical ventilatory support

OBJECTIVE

In acute respiratory failure, gas exchange improves with spontaneous breathing during airway pressure release ventilation (APRV). The mechanisms for this improvement are not fully clear. We have shown that APRV with spontaneous breathing reopens nonaerated lung tissue in dorsal juxtadiaphragmatic regions. We hypothesized that spontaneous breathing during APRV may redistribute ventilation and perfusion toward these reopened regions.

DESIGN

Prospective, randomized, controlled study.

SETTING

Animal research laboratory

SUBJECTS

Twenty controlled mechanically ventilated pigs.

INTERVENTIONS

Lung injury was induced by injection of oleic acid into the central circulation; thereafter, pigs were randomized to APRV with or without spontaneous breathing. To induce spontaneous breathing during APRV with spontaneous breathing, the mechanical respiratory rate was decreased by 50% in this group.

MEASUREMENTS AND MAIN RESULTS

We measured respiratory mechanics, hemodynamics, gas exchange including the multiple inert gas elimination technique, and the spatial ventilation and perfusion distribution using single photon emission tomography. At similar minute ventilation and airway pressures, shunt remained stable during APRV with spontaneous breathing, whereas it increased during APRV without spontaneous breathing during the 2-hr study period (p = .006). Single photon emission tomography showed more ventilation (p < .001) and pulmonary blood (p < .025) flow in dorsal, juxtadiaphragmatic lung regions when spontaneous breathing was present.

CONCLUSIONS

The beneficial effects of spontaneous breathing on intrapulmonary shunt and oxygenation are explained both by increased ventilation of aerated dependent lung tissue and by opening up nonaerated tissue so that ventilation is distributed to a larger share of the lung. Redistribution of perfusion is possibly secondary to the altered ventilation. The overall effect is a more efficient use of available lung tissue for gas exchange.

Neuromuskuläre Wirkzeiten von Rocuronium am Diaphragma, Musculus adductor pollicis und orbicularis oculi in zwei Altersgruppen

OBJECTIVE

Onset time and recovery from non depolarising neuromuscular blockade depends on the tested muscle and is influenced by the age of the patient. This study compares the neuromuscular blocking effect of rocuronium on the diaphragm, adductor pollicis and orbicularis oculi muscle in young and elderly patients.

METHODS

After institutional ethics committee approval and written informed consent, 20 adult patients (ASA I - II), age 18 - 59 and > 65, have been included. Neuromuscular response was measured by accelerography for the adductor pollicis and orbicularis oculi muscle. Monitoring of the diaphragm consisted of measurement of the airway pressure against an occluded tracheal tube during magnetic phrenic nerve stimulation. Onset time and recovery were measured after injection of 0.6 mg/kg Rocuronium.

RESULTS

The adductor pollicis had the fastest onset time ( young 2.3 min, old 2.2 min), followed by diaphragm ( young 3.6 min, old 3.4 min) and orbicularis oculi muscle ( young 3.7 min, old 4.8 min). There was a complete blockade of the diaphragm in 50 % of all patients (Adductor pollicis 100 %, orbicularis oculi 40 %). Neuromuscular recovery, recovery index and TOF 0.8 differed significantly between young and elderly patients. Onset of recovery was earlier at the diaphragm ( young 15.9 min, old 22.0 min) compared to the peripheral muscles (adductor pollicis young 25.6 min, old 37.9 min, orbicularis oculi young 23.8 min, old 27.5 min).

CONCLUSION

2 fould ED95 of rocuronium often results in an incomplete neuromuscular blockade of the diaphragm. Therefore monitoring of the peripheral muscles in patients given a single dose of rocuronium often overestimates the degree of diaphragmatic relaxation, but is a save predictor of recovery. Especially in elderly patients were prolonged neuromuscular blockade should be expected, a neuromuscular monitoring is recommended.