Limited effects of crop foliar Si fertilization on a marginal soil under a future climate scenario

Growing crops on marginal lands is a promising solution to alleviate the increasing pressure on agricultural land in Europe. Such crops will however be at the same time exposed to increased drought and pathogen prevalence, on already challenging soil conditions. Some sustainable practices, such as Silicon (Si) foliar fertilization, have been proposed to alleviate these two stress factors, but have not been tested under controlled, future climate conditions. We hypothesized that Si foliar fertilization would be beneficial for crops under future climate, and would have cascading beneficial effects on ecosystem processes, as many of them are directly dependent on plant health. We tested this hypothesis by exposing spring barley growing on marginal soil macrocosms (three with, three without Si treatment) to 2070 climate projections in an ecotron facility. Using the high-capacity monitoring of the ecotron, we estimated C, water, and N budgets of every macrocosm. Additionally, we measured crop yield, the biomass of each plant organ, and characterized bacterial communities using metabarcoding. Despite being exposed to water stress conditions, plants did not produce more biomass with the foliar Si fertilization, whatever the organ considered. Evapotranspiration (ET) was unaffected, as well as water quality and bacterial communities. However, in the 10-day period following two of the three Si applications, we measured a significant increase in C sequestration, when climate conditions where significantly drier, while ET remained the same. We interpreted these results as a less significant effect of Si treatment than expected as compared with literature, which could be explained by the high CO2 levels under future climate, that reduces need for stomata opening, and therefore sensitivity to drought. We conclude that making marginal soils climate proof using foliar Si treatments may not be a sufficient strategy, at least in this type of nutrient-poor, dry, sandy soil.

[Innovative 3D imaging]

Intraoperative 2D fluoroscopy is often performed for repositioning and implant control. However, this does not always provide the details needed to reliably detect joint steps or incorrect repositioning. Over the last few years, intraoperative 3D imaging has been established and further developed. Multiple studies demonstrate an advantage and better intraoperative control through 3D imaging. Examples are the upper ankle, the proximal tibia and the distal radius; the rates of intraoperative revisions with digital volume tomography (DVT) are between 20-30%. Technical advancements, such as metal artifact reductions, automated plane setting, automated screw detection, and robotic DVT devices, facilitate intraoperative operation, shorten surgical time, and provide improved image quality. By processing the data sets in the form of an immersive, computer-simulated image in terms of "augmented reality" (AR), increased precision can be achieved intraoperatively while reducing radiation exposure. The implementation of these systems is associated with costs, which are offset by cost savings from avoided revisions. Adequate counter-financing is still lacking at the present time. Intraoperative 3D imaging represents an important tool for intraoperative control. The current data situation makes it necessary to address the routine use of 3D procedures, especially in the joint area. The indications are becoming increasingly broader. Technical innovations such as robotics and AR have significantly improved 3D devices in recent years and offer high potential for integration into the OR.

[Unilateral phrenic nerve paralysis after vertical infraclavicular plexus block]

We present a case of a rapid onset reversible phrenic nerve block following vertical infraclavicular blockade of the brachial plexus. Five minutes after injection of local anaesthetics the SpO2 fell to 80%. Oxygen supplementation was required during the perioperative period to maintain normoxemia. The postoperative X-ray showed an elevated diaphragm of the ipsilateral side. After five hours oxygen supply could be terminated, an X-ray control the next day showed normal bilateral diaphragm position.

[Continuous peridural analgesia vs patient - controlled intravenous analgesia for pain therapy after thoracotomy]

OBJECTIVES

Continuous epidural analgesia (EA) and patient-controlled intravenous analgesia (PCA) are widely used for postoperative pain control. Studies indicate that both analgesic regimens provide good analgesia after major surgery. However, because of the following reasons it is still unclear whether one of the two modes of application is superior. First, there are conflicting data regarding the differences in pain relief and drug use between epidural and intravenous administration of opioids. Second, in many studies epidural analgesia is performed by a combination of local anaesthetics and opioids. Third, reduced morbidity was observed only in some of the studies, in which epidural analgesia provided better pain relief than systemic opioid supply. Despite these conflicting results, EA with local anaesthetics and fentanyl as well as PCA with piritramid, a highly potent mu-agonist, are routinely used in Germany. The purpose of this study was to compare these two treatments for analgesic efficacy, pulmonary function, incidence of side effects and complications in patients undergoing thoracotomy.

METHODS

In this prospective randomized trial 50 patients were included. For postoperative pain control 25 patients (EA group) received thoracic epidural infusion of local anaesthetics (bupivacaine 0.125% or ropivacaine 0,2%) and fentanyl 4,5 microg/ml with a flow rate of 4-10 ml/h. 25 patients received intravenous PCA with piritramid (bolus 2, 5 mg, lock out 15 minutes, maximum of 25 mg/4 h, no background infusion).

RESULTS

Analgesia at rest and while coughing, as evaluated by visual analogue scale, was significantly better in the EA group. EA also resulted in superior values of pulmonary function tests, general condition and a lower incidence of sedation and nausea. In contrast, patients with EA reported distinctly more pruritus than patients with PCA. Duration of hospital stay was shorter in the EA group, but this difference did not reach statistical significance. There was one atelectasis in the EA group. No major complications related to EA or PCA were observed.

CONCLUSION

In this study EA with local anaesthetics and fentanyl provided superior postoperative pain control and a lower incidence of sedation and nausea compared to intravenous PCA with piritramid, but there was no superiority as to pulmonary complications and duration of hospital stay.

Lung procurement by low-potassium dextran and the effect on preservation injury. Munich Lung Transplant Group

BACKGROUND

This clinical study was performed to evaluate the effect of low-potassium dextran (LPD) solution on organ function in human lung transplantation.

METHODS

A total of 80 patients were included in this study. Donor lungs were flushed with Euro-Collins (EC) solution in 48 cases or LPD (Perfadex) in 32 cases. Subsequently, single- (EC: n = 31; LPD: n = 15) or double-lung transplantations (EC: n = 17; LPD: n = 17) were performed. The evaluation parameters of transplant function were the reperfusion injury score (grade I to V); the alveolar/arterial oxygen ratio; the duration of respirator therapy; and the length of intensive care treatment and survival.

RESULTS

Incidence and severity of reperfusion injury score were more severe in the EC group (31 of 48: grade I: n = 13; II: n = 8; III: n = 5; IV: n = 2; V: n = 3; LPD group: 17 of 32 patients; grade I: n = 12; II: n = 1; III: n = 3; IV: n = 0 grade V: n = 0), leading to death in three patients. In the LPD group, despite of the use of cardiopulmonary bypass, alveolar/arterial oxygen ratio values were significantly (P = 0.009) better during the early postoperative phase. Thirty-day mortality was 12% in the EC group and 6% in the LPD group. The one-year survival rate was 79% after the use of LPD (vs. EC: 62%).

CONCLUSIONS

Graft preservation using LPD leads to better immediate and intermediate graft function after pulmonary transplantation and also results in better long-term survival.

Leukocyte sequestration in pulmonary microvessels and lung injury following systemic complement activation in rabbits

Inflammatory reactions are associated with sequestration of leukocytes in the lung. Complement activation leads to accumulation of leukocytes in alveolar septa and alveoli, to lung edema and hemorrhage. Although in organs other than the lung leukocytes interact with the vascular endothelium only in postcapillary venules, alveolar capillaries are considered to be the site of leukocyte sequestration in the lung. However, pulmonary venules and arterioles have not been investigated systematically after complement activation so far. A closed thoracic window was implanted in anesthetized rabbits; leukocytes and red blood cells were stained, and the movement of these cells was measured in superficial pulmonary arterioles, venules and alveolar capillaries using fluorescence video microscopy before and 30 and 60 min after infusion of cobra venom factor (CVF). Erythrocyte velocity and macrohemodynamic conditions did not change after CVF infusion and were not different from the sham-treated controls. The number of sticking leukocytes increased significantly compared to baseline and control: by 150% in arterioles and in venules and by 740% in alveolar capillaries within 60 min after CVF infusion. The width of alveolar septa in vivo was significantly enlarged after CVF infusion, indicating interstitial pulmonary edema. At the end of the experiments, myeloperoxidase activity was higher in the CVF group, showing leukocyte sequestration in the whole organ. It is concluded that complement activation by CVF induces leukocyte sequestration in lung arterioles, venules and alveolar capillaries and leads to mild lung injury.

Cardiopulmonary exercise testing before and after lung and heart-lung transplantation

Heart-lung (HLT) and lung transplantation (LT) have been shown to be effective procedures for patients with end-stage cardiopulmonary disorders. As yet, few data exist on the exercise performance of patients before and after thoracic transplantation except with regard to 6-min walk tests. In this article we report cardiopulmonary exercise test results of lung and heart-lung transplant recipients in comparison with their pretransplant values. We studied 103 consecutive recipients of single-lung (n = 46), bilateral lung (n = 32), and heart-lung (n = 25) transplants. Cardiopulmonary exercise testing with a cycle ergometer was performed before and shortly after surgery. Before transplantation, all patients showed severe exercise intolerance and markedly impaired parameters reflecting cardiopulmonary function (e.g., work capacity: 20 +/- 11% predicted; oxygen uptake: 34 +/- 12% predicted; oxygen pulse: 50 +/- 18% predicted; functional dead space ventilation: 57 +/- 10% of minute ventilation; alveolar-arterial oxygen difference during exercise: 79 +/- 15 mm Hg). At 55 +/- 9 d after transplantation, transplant recipients reached maximum oxygen uptakes in the range of 22 to 71% of predicted values; the peak oxygen uptake was increased after transplantation (13.1 +/- 3.4 ml/min/kg versus 10.4 +/- 3.8 ml/min/kg; p < 0.001). Work capacity, oxygen pulse, tidal volume, and peak minute ventilation did not differ in patients following single- or double-lung tranplantation or HLT. Ventilatory factors did not appear to limit exercise capacity in any group. Despite the persistent limitations in aerobic capacity and work rate seen in many of the recipients, cardiopulmonary performance is reasonably well restored shortly after LT and HLT.

Expression of adhesion molecules on circulating polymorphonuclear leukocytes during orthotopic liver transplantation

After ischemia-reperfusion, polymorphonuclear leukocytes (PMNLs) become activated by inflammatory mediators, adhere to the vascular endothelium via the interaction of specific adhesion molecules, and cause tissue injury by the release of cytotoxic oxygen radicals and enzymes. Results obtained in animal experiments suggest a key role for PMNLs in ischemia-reperfusion injury of transplanted livers; therefore, we studied the expression of adhesion molecules on circulating PMNLs (beta2-integrins [CD18] and L-selectin [CD62L]) in 20 patients undergoing orthotopic liver transplantation (study group). To determine the effects of surgical trauma to the liver in the absence of ischemia and reperfusion, the expression of PMNL adhesion molecules was measured in 10 patients scheduled for elective partial liver resection without hepatic vascular exclusion (control group). Patients were classified as responders or nonresponders based on changes in the expression of adhesion molecules elicited by reperfusion. In the control group, all patients remained nonresponders, showing that surgical trauma of the liver alone does not cause activation of circulating PMNLs. In contrast, 8 of 20 patients in the study group were classified as responders. In responders, postoperative serum liver enzyme activities were significantly higher than in nonresponders, indicating that activation of PMNL was associated with damage to hepatocellular integrity. Because expression of adhesion molecules was already changed during surgery, monitoring of the expression of beta2-integrins and L-selectin on circulating PMNLs during orthotopic liver transplantation might be useful in prediction of early graft dysfunction.

Microhemodynamics and leukocyte sequestration after pulmonary ischemia and reperfusion in rabbits

OBJECTIVE

Investigation of leukocyte sequestration in alveolar capillaries and of microhemodynamic changes after pulmonary ischemia/reperfusion injury.

METHODS

The kinetics of leukocyte passage and the hemodynamics in pulmonary microcirculation were investigated in 16 rabbits by intravital microscopy. Mean red blood cell velocity and the number of sticking leukocytes were measured in pulmonary arterioles, venules, and capillaries after 1 hour of tourniquet ischemia and 10 minutes and 1 hour after reperfusion.

RESULTS

The decrease of red blood cell velocity after reperfusion was associated with a largely increased heterogeneity of blood flow. Immediately after the onset of blood flow, sequestered leukocytes were found in all microvascular segments. An increased number of leukocytes was present in arterioles, venules, and alveolar capillaries 10 minutes and 1 hour after reperfusion. Concomitantly, width of alveolar septa was increased while arterial oxygen tension was reduced, indicating the development of interstitial pulmonary edema.

CONCLUSION

Leukocytes are sequestered after pulmonary ischemia and reperfusion not only in alveolar capillaries but also in arterioles and venules, and they may contribute to the development of reperfusion edema.

Perioperative management of patients undergoing lung transplantation

This review focuses on recent developments in the perioperative management of patients undergoing lung transplantation. Relevant current literature and the experience of the Munich Lung Transplant Group were taken into consideration. Recent advances include the use of inhalational nitric oxide for the treatment of early graft dysfunction and the use of aerosolized cyclosporine for the treatment of recurrent and steroid-resistant acute rejection. Opportunistic infections remain a major source of morbidity and mortality in lung transplant recipients.

[Discharge following ambulatory anesthesia]

Beyond strict selection of suitable patients the adequate choice of the best moment for discharge home is essential for safety and efficacy of outpatient surgery. Restitution of cardiovascular stability and psychomotoric function is completed at the end of observation in the recovery unit. Further prerequisites of home discharge are absence of postoperative nausea and vomitus as well as sufficient pain control by non-opioids and physical measures. The definition of fixed observation periods is unreasonable, technical examinations and psychomotoric tests are of minor importance. Home readiness has to be evaluated by a physician before discharge. Standardized scores or checklists may be of some help. The modalities of patient care after discharge are checked prior to surgery. During late postoperative recovery, continuous care of a responsible adult is required for at least 24 hours. During this time period certain restrictions must be respected, e.g. from driving and business contracts. Even after this time some residual effects of anesthesia may still be present.

[The anesthetist in perioperative care]

Due to the recent development in operative medicine medical and organizational demands on perioperative patient care have changed significantly. Corresponding to the responsibility of the operative colleagues for therapy of the primary disease, anesthesiologists have to account for monitoring and treatment of vital functions throughout the perioperative period, starting from preoperative evaluation until postoperative care. The postanesthesia recovery unit has a key role in perioperative management. Beyond post-operative monitoring and stabilization of vital parameters it is increasingly used as a buffer and switch operating station, where patients are prepared and allocated to a normal ward, an observation or intensive care unit for subsequent postoperative care. The recovery unit has developed to a "multitasking" care center, which should be operational 24 h a day with an anesthesiologist present during working hours. The terminology should be changed in the future in order to better characterize the new task spectrum, e.g. in perioperative anaesthetic care unit (PACU) for medical and medicolegal reasons patient security must have absolute priority above economic aspects. Effective postoperative pain control using epidural or patient-controlled intravenous analgesia may increase patient comfort and reduce postoperative complications caused by sympathoadrenergic activation. Both method can be safely used on normal wards provided that close cooperation and training of ward personnel is guaranteed as well as continuous supervision by a specialized acute pain service.

Contribution of selectins to leucocyte sequestration in pulmonary microvessels by intravital microscopy in rabbits

1. Sequestration of leucocytes in the lung is the net result of leucocyte rolling and sticking in pulmonary arterioles and venules and their retention in alveolar capillaries. 2. In order to investigate whether adhesion molecules of the selectin family contribute to these phenomena the effects of fucoidin (an inhibitor of L- and P-selectin) on microhaemodynamics and leucocyte kinetic were studied in pulmonary arterioles, capillaries and venules by means of intravital fluorescence microscopy in a rabbit model. 3. Fucoidin reduced leucocyte rolling in pulmonary arterioles and venules by 75 and 83%, respectively, without affecting leucocyte sticking. In alveolar capillaries, fucoidin reduced leucocyte retention and accelerated leucocyte passage, thus reducing the alveolar transit time of leucocytes by 62%. 4. It is concluded that rolling of leucocytes in pulmonary microvessels is mediated by selectins, whereas sticking relies on selectin-independent mechanisms. 5. Leucocyte retention in alveolar capillaries is not due solely to mechanical hindrance of leucocyte passage through narrow vessel segments, as previously hypothesized, but also depends on interaction of leucocytes with the capillary endothelium.

[The effects of aprotinin. Blood loss and coagulation parameters in orthotopic liver transplantation: A clinical-experimental, prospective and randomized double-blind study]

The effect of aprotinin (2,000,000 IU as a bolus +500,000 JU/h until the end of the operation) on transfusion requirements and coagulation parameters in orthotopic liver transplantation (study group: n = 9; placebo group: n = 9) was investigated in a randomised, double-blind study. Coagulation parameters were monitored intraoperatively using a mobile laboratory. In contrast to the published results, no effect on transfusion requirements could be demonstrated. However, aprotinin showed a positive effect on some coagulation parameters in the reperfusion phase. The mechanism appeared to be inhibition of the contact activation of the intrinsic system with less thrombin generation in the study group.

Prediction of the transfusion effect of platelet concentrates as measured by a model of primary hemostasis ex vivo

A method to determine primary hemostasis ex vivo (Thrombostat) was modified to monitor the transfusion effect of platelet concentrates (PC) in 12 patients with thrombocytopenia following bone marrow transplantation. It was possible to measure platelet function in patients with a platelet count lower than 2 x 10(10)/l. In addition, the platelet aggregometer (Born) was adapted to determine cell function in PC anticoagulated with acid citrate dextrose of citrate phosphate dextrose. It was possible to make a prediction (r = 0.89) of the effect of a given PC on a patient's ex vivo primary hemostasis parameters. Platelet aggregation following addition of 20 muM ADP to PC, obtained from 12 single donors, resulted in an average maximal light transmission (light transmission/age of concentrate in days) of 61%/1 day and 37%/5 days, respectively. The same experiment gave only 39%/1 day and 13%/4 days for pooled platelets. To avoid possible immunization and bleeding complications, a reliable monitoring of platelet transfusion seems highly desirable.

[Neurologic complications following total endoprothesis implantation of the hip under peridural catheter anesthesia]

This case report describes paralysis of the plantar flexors and extensors after a total hip replacement in a 33-year-old woman performed under epidural anaesthesia (PDA). Six years previously, the patient had undergone a bone marrow transplantation for chronic myeloid leukaemia. She had developed a deep vein thrombosis, a pulmonary embolus, and a severe graft-versus-host reaction of the skin, leading to markedly reduced mouth opening. The hip operation was performed using PDA following antithrombotic prophylaxis with low-molecular-weight heparin. Blood could initially be aspirated after advancing the PDA catheter, and a second puncture of the epidural space 1 segment higher enabled correct placement of the catheter. The patient received 500 ml Dextran 60 perioperatively and the operation was completed without any further problems. The PDA catheter was removed 2 h after the operation following the return of movement of both thighs. Fourteen hours after the completion of surgery it was noticed that the dressing over the epidural puncture site was bloodstained, the patient was incontinent, and complete loss of movement of the operated leg was present. An epidural haematoma was the suspected cause, but could not be definitely confirmed by a CT scan. Nevertheless, a laminectomy was undertaken to evacuate the suspected haematoma. As expected, tracheal intubation was only possible bronchoscopically. Intraoperatively, some low-grade epidural oozing at the level of the initial puncture site was observed, and a hemilaminectomy of 5 was performed. For the first time postoperatively, the bleeding time was measured and was markedly prolonged to 20 min (as described by Mielke, normal value up to 8 min). A coagulopathy was suggested, with the differential diagnosis of impaired platelet function. The paralysis of the plantar flexors and extensors and some sensory loss were still present 6 months after the operation. It remains uncertain whether the PDA in a patient receiving low-molecular-weight heparin resulting in a the suspected epidural haematoma was the cause of the neurological sequelae and in agreement with the consultant neurologist, we believe that a direct traumatic lesion of the L5/S1 segment or damage to the sciatic nerve are also likely causes of the symptoms. Undoubtedly, the lack of adequate postoperative neurological monitoring and the intraoperative administration of dextran despite the known epidural vascular lesion deserve criticism. This case report demonstrates the often complex development of neurological complications after nerve blocks, where a definite cause can frequently not be determined.

[Thromboembolism prevention with low dose heparin and spinal anesthesia--a risky combination?]

Spinal or intracranial haematoma is a rare but severe complication of spinal/epidural anaesthesia with an incidence of less than 1:100,000. Coagulation defects, traumatic puncture, and anticoagulant drugs are assumed to be risk factors for the development of this kind of haematoma. Whether the risk of bleeding after spinal/epidural anaesthesia is increased by the administration of low-dose heparin (unfractionated or fractionated) for thromboprophylaxis is currently under discussion.

METHODS AND RESULTS

A randomised, prospective trial answering this question is not feasible because of the rarity of the complication. As an alternative, we identified all case reports described in the literature to date and analysed them for possible risk factors. In conjunction with spinal/epidural anaesthesia, we found 4 cases of spinal and 2 cases of intracranial haematoma following treatment with unfractionated heparin and 6 cases of spinal haematoma following treatment with different low-molecular-weight (LMW) heparins. In none of these cases could thromboprophylaxis with heparin be identified as the only risk factor for bleeding: in 11 of the 12 cases a difficult or traumatic puncture was described. Eleven patients showed three or more possible risk factors, e.g., coagulation defects, concomitant therapy with other anticoagulant drugs, or anatomic abnormalities.

CONCLUSION

We suggest that the development of spinal or intracranial haematoma after spinal/epidural anaesthesia is a multifactorial event. An influence of low-dose heparin prophylaxis as a cofactor cannot wholly be excluded because of the difficulty of studying the problem in a prospective way. The few case reports have to be seen in the context of millions of patients who have received either unfractionated or LMW heparin and lumbar or thoracic regional anaesthesia without any complication. We conclude that low-dose heparin prophylaxis (fractionated or unfractionated) is not a definite contraindication to spinal/epidural anaesthesia. High-risk (ASA III/IV) patients in particular benefit from effective postoperative analgesia achieved by local anaesthetics in combination with effective heparin thromboprophylaxis. Nevertheless, the absolute contraindications for regional anaesthesia must be respected and an individual risk/benefit analysis should be performed for every patient. An adequate time interval between application of heparin and regional anaesthesia or removal of a spinal/epidural catheter, atraumatic puncture technique, and careful neurologic monitoring during the post-operative period can minimise the risk of complications.

Results of liver transplantation for gastroenteropancreatic tumor metastases

During the early 1980s liver transplantation (LTx) was expected to be a promising therapeutic option for patients with primary or secondary tumors confined to the liver. Because of disappointing results owing to death from early recurrence, LTx is currently restricted to well selected patients with small primary tumors and, in the case of liver metastases, to those with metastases of gastroenteropancreatic (GEP) tumor origin only. In our series of 300 liver transplantations four patients with GEP tumor metastases underwent LTx. The primary tumors were one neuroendocrine kidney tumor, one glucagonoma of the pancreas, and two cases of carcinoids of the pancreas. Because of local metastatic lymph node involvement upper gastrointestinal exenteration followed by LTx was performed in two patients. No patient survived beyond 33 months after LTx. Three patients died from tumor recurrence. In one patient who died from fungal sepsis autopsy revealed spine metastases that had been missed before LTx. Our dismal results do not compare well with promising data published previously by others for this particular patient group. Under the pressure of an increasing donor organ shortage, patients with GEP tumor metastases should be selected carefully for LTx.

Perioperative mucosal pH and splanchnic endotoxin concentration in orthotopic liver transplantation

Although impairment of splanchnic perfusion may induce mucosal hypoxia and endotoxaemia during orthotopic liver transplantation (OLT), little is known about the changes in mucosal oxygenation during and after the procedure. To study the effects of liver surgery itself on mucosal pH (pHi) and the response of pHi to acute changes in portal flow, we measured gastric pHi during six liver resections using tonometry: in two patients, after clamping of the hepatoduodenal ligament, pHi decreased within 30 min and recovered promptly after reperfusion. We then investigated gastric and sigmoid pHi (pHig, pHis) during the perioperative phase in 18 OLT. Median pHi values were low before surgery (pHig 7.28 (first/third quartiles 7.22/7.34); pHis 7.27 (7.12/7.36)). Although global oxygen delivery and haemodynamic variables remained constant and veno-venous bypass (VVB) was used to maintain portal flow, pHi declined during the anhepatic phase (pHig 7.19 (7.13/7.23), P < 0.01; pHis 7.13 (7.06/7.24), P < 0.05). After reperfusion of the graft, pHi recovered and did not differ from baseline values by the end of OLT. After operation pHig increased further, reaching the highest values 30 h after ICU admission (7.34 (7.26/7.38)). In the intraoperative period, no significant endotoxaemia was observed either in portal or systemic blood. The maximum reduction in pHi was related neither to the duration of VVB and OLT nor to the number of red cell units transfused. pHi after reperfusion did not correlate with graft viability or dysfunction of the lung or kidney. We conclude that pHi indicates mucosal ischaemia during OLT which is not necessarily associated with endotoxaemia, and intraoperative pHi monitoring does not appear to be a valuable predictor of postoperative graft failure and organ dysfunction.

Effect of blood flow on the leukocyte-endothelium interaction in pulmonary microvessels

Circulating leukocytes are retained in the microcirculation of the lung. The site of leukocyte retention, however, is still a subject of controversy, and the effects of microvascular blood flow on the leukocyte-endothelium interaction in pulmonary microvessels are unknown. We used in vivo fluorescence microscopy to analyze microhemodynamics and the flow behavior of in vivo-labeled leukocytes in pulmonary arterioles, venules, and alveolar capillaries. Microvascular blood flow was altered by variation of cardiac output. Leukocytes were found to roll and to stick on arteriolar and more pronouncedly on venular endothelium. During their passage through alveolar capillaries, a fraction of passing leukocytes became static for 0.1 to > 5 s. Under control conditions, leukocytes were concentrated approximately 8-fold more in arterioles and 24-fold more in venules than in the blood passing through these vessels. The concentration in capillaries was 1.5 times greater than in venules. The velocity of rolling leukocytes in arterioles and venules correlated significantly with the shear rate in these vessels, whereas the density of sticking cells was negatively correlated with the shear rate. The differences between leukocyte rolling and sticking in arterioles and in venules cannot be explained by respective hemodynamic conditions. In alveolar capillaries, the percentage of temporarily static leukocytes and the time of their stasis were inversely correlated with red-blood-cell (RBC) velocity. We conclude that leukocytes are retained in pulmonary arterioles, venules, and alveolar capillaries according to microvascular blood flow and endothelial factors.

Hemodynamic effects of anesthetic induction with eltanolone-fentanyl versus thiopental-fentanyl in coronary artery bypass patients

We evaluated the hemodynamic profile of eltanolone and fentanyl versus thiopental and fentanyl anesthetic induction in patients with documented coronary artery disease. Fifty patients scheduled for coronary artery bypass grafting were randomly assigned to two treatment groups (25 patients each). Anesthesia was induced by eltanolone (0.5 mg/kg) or by thiopental (3 mg/kg). Each patient also received 3 micrograms/kg fentanyl and 0.1 mg/kg vecuronium. Heart rate, arterial, pulmonary arterial, central venous, and pulmonary capillary wedge pressures, and cardiac output were determined in the awake state, 2 min after induction of anesthesia, and at 1 and 5 min after intubation, which was performed 3 min after induction. Between-group statistics showed significantly (P < 0.05) lower mean arterial pressure and systemic vascular resistance for eltanolone-treated patients at all measuring points. Pulmonary capillary wedge pressure was lower at 1 min after intubation; left ventricular stroke work index was lower at 1 and 5 min after intubation in the eltanolone group. We conclude that the lower mean arterial pressure with eltanolone as compared to thiopental is a result of greater peripheral vasodilation.

[The effect of mechanical ventilation, thoracotomy, and one-lung respiration on intrapulmonary perfusion distribution. An animal experimental study]

The physiological pattern of regional pulmonary blood flow is mainly determined by the relationship of pulmonary arterial, venous, and alveolar pressures. Changes in alveolar pressure and pulmonary geometry may therefore be expected to influence regional perfusion, which is a key determinant of pulmonary gas exchange. Unilateral thoracotomy is usually performed with the patient in the lateral decubitus position. The present study examined the influence of mechanical factors on regional pulmonary blood flow distribution in rabbits in the lateral decubitus position during normoxia and unilateral hypoxia. METHODS. Anaesthetised white New Zealand rabbits (n = 8) weighing 2200-3900 g (mean = 2860 g) received central venous injections of radioactive microspheres while in the left lateral decubitus position during spontaneous breathing (SB) and during mechanical ventilation (two-lung ventilation, 2LV), under closed (2LVC) and open chest (2LVT) conditions, as well as during unilateral hypoxia of the nondependent lung induced by nitrogen inflation (1LVN) or atelectasis (1LVA). The method used for one-lung ventilation (1LV) has been previously described in detail. Arterial, central venous, and pulmonary arterial pressures were recorded continuously. Lungs were excised, dried in the inflated state, and cut into 16 sagittal slices, which were further divided into lobar components, the lower lobes into center and periphery. The radioactivity of each specimen was measured in a gamma-counter; perfusion of the individual tissue specimens was quantified using the software program MIC III. The Friedman test followed by paired comparisons according to Conover was used for statistical analysis of differences between the experimental phases. Perfusion of central and peripheral parts of isogravitational slices was compared by use of the Wilcoxon matched pairs test. Values are given as means +/- SE; the level of significance was P < 0.05 unless otherwise indicated. RESULTS AND DISCUSSION. Haemodynamic parameters did not differ significantly between the experimental phases (Table 1). Compared to 2LV, a significant increase in venous admixture (P < 0.05) and a corresponding decrease in PaO2 (P < 0.01) were observed during 1LV. This effect was significantly more pronounced during 1LVA as compared to 1LVN (P < 0.01). Since inspiratory pressure was kept constant throughout the experiments, moderate respiratory acidosis developed during both phases of 1LV. Regional perfusion (Qr) of the nondependent lung was slightly reduced during 2LVC compared to SB and 2LVT. One-lung ventilation induced a significant decrease in perfusion of the hypoxic lung (P < 0.001 1LVN, 1LVA vs. SB,2LVC,2LVT). In accordance with the data obtained from blood gas analysis and oximetry, this effect was more pronounced during N2 insufflation than during atelectasis (P < 0.01 1LVN vs. 1LVA). Among the factors that may account for this effect, PaCO2 did not differ significantly between both phases of 1LV. During N2 insufflation PO2 at the hypoxia-sensitive site is lower than during atelectasis, where it equals mixed-versus PO2 (PvO2). The difference in local PO2 is unlikely, however, to have caused the changes in regional perfusion between 1LVN and 1LVA, since PvO2 was as low as 40 mmHg during 1LVA and the pulmonary vascular response to hypoxia has been found to reach its maximum in this PO2 range [2, 11]. Enhanced redistribution of regional perfusion during 1LVN as compared to 1LVA is therefore most likely attributed to differences in alveolar pressure and pulmonary geometry. Apart from a radial perfusion gradient in the right lower lobe during 2LVC and 2LVT, no isogravitational Qr gradients were observed. CONCLUSION. We conclude that controlled mechanical ventilation in the lateral decubitus position causes only minor changes in vertical blood flow distribution.

[Noninvasive ventilation after lung transplantation]

BACKGROUND

Non-invasive mechanical ventilation (NIPPV) is an accepted choice of treatment in patients with chronic pulmonary disease and/or acute respiratory failure. Recently NIPPV was also proposed in the postoperative weaning period.

PATIENTS AND METHODS

Six of 30 patients after lung transplantation were were extubated despite a weaning failure was predicted using well accepted weaning criteria. Therefore, the 6 patients were treated with intermittent-noninvasive ventilation using assisted modes of mechanical ventilation (PSV/CPAP).

RESULTS

Both, oxygenation (increase in paO2: 18 mm Hg during PSV, 11 mm Hg during CPAP) and pulmonary mechanics (decrease in respiratory rate: 14/min during PSV, 10/min during CPAP; increase in tidal volume: 5 ml/kg during PSV, 3 ml/kg KG during CPAP) improved and the energy expenditure decreased (19% during PSV, 12% during CPAP).

CONCLUSION

Non-invasive ventilation after lung transplantation enables earlier extubation and prevents weaning failure.

Long-term evaluation of a continuous intra-arterial blood gas monitoring system in patients with severe respiratory failure

OBJECTIVE

The purpose of this study was to evaluate the reliability and accuracy of a new continuous intra-arterial blood gas monitoring system (IABG; PB3300, Puritan Bennett) over a prolonged period of time (> 7 days).

DESIGN

Prospective criterion standard study.

SETTING

Anesthesiological intensive care unit in a university hospital.

PATIENTS

11 sensors were tested in 10 mechanically ventilated patients with severe respiratory failure.

INTERVENTIONS

PO2, PCO2, and pH measured using IABG were compared to values obtained from 2 conventional blood gas analyzers. The quality of blood pressure tracings was assessed using a scoring system consisting of 5 grades.

RESULTS

The median study period was 205h/sensor (range: 169-506h). 320 blood samples were obtained. The ranges of measured parameters were: PO2 = 46-433 mmHg, PCO2 = 25-79 mmHg, pH = 7.25-7.55. The mean (SD) differences for the whole study period were: -4.3 (11.9) mmHg for PO2, for the clinically important range (PO2 < 150 mmHg) -1.9 (5.4) mmHg, -2.8 (4.5) mmHg for PCO2, and -0.03 (0.04) for the pH value. The MD (SD) in relation to the sensor lifetime were for days 1-3: -1.1 (5.1) mmHg for PO2, -0.4 (3.9) mmHg for PCO2, and -0.01 (0.03) for the pH value; for days 4-6: -1.5 (6.0) mmHg for PO2, -3.3 (4.0) mmHg for PCO2, and -0.03 (0.03) for the pH value; for days 7-9: -2.5 (4.7) mmHg for PO2, -5.1 (4.6) mmHg for PCO2, and -0.04 (0.04) for the pH value; for days > 9: -4.9 (4.4) mmHg for PO2, -5.3 (4.1) mmHg for PCO2, and -0.05 (0.03) for the pH value.

CONCLUSIONS

The IABG reliably measured blood gases and pH values with acceptable clinical performance based on the overall results. There was, however, a decline in the agreement of the sensors and conventional values with increasing sensor lifetime. The mean differences (bias) and the standard deviation of differences (precision) of PO2, PCO2 and the pH values were acceptable for clinical purposes up to day 6. The arterial blood pressure tracings and blood withdrawal were not adversely affected. No side effects due to the sensors occurred. In summary, a prolonged sensor use for a period of up to 6 days appears to be reasonable. This system offers on-line information on oxygenation, ventilation, and acid-base status and allows immediate detection of acute and potentially life-threatening events.

Quality control of platelet concentrates by the Thrombostat 4000

Quality control of platelet concentrates (PC) is an important prerequisite for good transfusion praxis. However, direct measurement of platelet function is complex, since available methods (e.g. aggregometry, serotonin release) are time consuming and require special equipment. Therefore a test system is needed, which is easy to handle, fast, and achieves reliable results. The present paper compares the results of conventional platelet function tests with those of a modified in-vitro bleeding test (IVBT) (Thrombostat 4000) in liquid-stored and cryopreserved PCs. A high correlation between aggregometry, serotonin release, GMP 140 expression upon stimulation, and IVBT was demonstrated. Therefore IVBT seems to be a good alternative to the conventional platelet function tests for quality control of PCs. In addition, a good correlation between the results of IVBT of patients' blood after PC transfusion and IVBT of patients blood before transfusion supplemented with platelets of the respective PC could be found. Therefore IVBT seems to be able to predict PC transfusion success. However, since these data were obtained in a small sample undergoing bone marrow transplantation, further studies are needed to verify this hypothesis.

Effects of isoflurane on regional pulmonary blood flow during one-lung ventilation

Isoflurane has been reported to inhibit hypoxic pulmonary vasoconstriction. However, the effects of one-lung ventilation and isoflurane on regional pulmonary blood flow (Qr) have not been investigated in detail. Therefore, using radionuclide labelled microspheres we measured Qr in rabbits (n = 8) in the left lateral decubitus position during two- and one-lung ventilation under i.v. baseline anaesthesia and during additional administration of 1.5% isoflurane. Macrohaemodynamic variables were recorded continuously. Isoflurane increased non-dependent lung blood flow during two-lung ventilation. One-lung ventilation caused a homogeneous decrease in Qr throughout the hypoxic lung, irrespective of isoflurane administration (P < 0.001). However, isoflurane significantly augmented Qr of the hypoxic lung during one-lung ventilation (P < 0.05). During all phases, Qr of the upper lobe was higher compared with that in the lower lobe in isogravitational slices of both lungs; a ventrodorsal perfusion gradient was found in the left upper lobe. We conclude that 1.5% isoflurane increased perfusion of the non-dependent lung, inhibited hypoxic pulmonary vasoconstriction-induced redistribution of pulmonary blood flow and did not influence isogravitational perfusion gradients.

Isoflurane inhibits hypoxic pulmonary vasoconstriction. An in vivo fluorescence microscopic study in rabbits

BACKGROUND

Contradictory results have been reported in previous studies investigating the effect of isoflurane on hypoxic pulmonary vasoconstriction by indirect approaches. The current study measured the effects of one-lung ventilation (1LV) and isoflurane 1.5% by direct visual observation of the pulmonary microcirculation.

METHODS

Ten New Zealand White rabbits were anesthetized with intravenous thiopental, alpha-chloralose, and piritramid. Arterial, central venous, pulmonary arterial, left atrial, and airway pressures and cardiac output were recorded continuously. 1LV was facilitated by a bronchial blocker in the right main bronchus. A transparent window was implanted into the right thoracic wall for videofluorescence microscopy of the subpleural pulmonary microcirculation. After intravenous injection of fluorescein isothiocyanate-labeled red blood cells, vessel diameters, red blood cell flux, red blood cell velocity, and dynamic microhematocrit were measured in pulmonary arterioles and venules during two-lung ventilation and 1LV during baseline anesthesia and with supplementary isoflurane 1.5%.

RESULTS

During intravenous anesthesia, 1LV caused significant reduction of vessel diameters and red cell flux and velocity and an increase in microvascular hematocrit in pulmonary arterioles and venules. The decreases in arteriolar diameters and red blood cell flux and velocity induced by 1LV were significantly attenuated by isoflurane as compared with those measured during baseline anesthesia (P = 0.010, P = 0.029 and P = 0.047). Accordingly, 1LV-induced reduction of venular red cell flux (P = 0.023) and velocity (P = 0.036) were less pronounced during isoflurane. Isoflurane caused a significant decrease in arterial pressure. Venous admixture increased and arterial oxygen tension decreased significantly during 1LV; the changes were more pronounced during 1LV with isoflurane 1.5% than during 1LV with baseline anesthesia.

CONCLUSIONS

1LV leads to a marked reduction of microvascular diameters and blood flow in the hypoxic lung. Isoflurane 1.5% inhibits hypoxic pulmonary vasoconstriction in pulmonary arterioles and increases regional blood flow in the hypoxic lung.

[Continuous intravascular blood gas analysis. Clinical evaluation of a new fiber optic monitor]

Continuous monitoring of blood gases and pH could add substantially to patient safety. During the last decade, efforts have been made to develop continuous optochemical blood gas sensors. The initial evaluation of such fibreoptic-based systems showed major patient-interface problems [11]. We evaluated a new intra-arterial blood gas monitoring system (PB3300, Puritan-Bennett, Carlsbad CA) under routine clinical conditions. METHODS. After institutional review board approval and with written informed consent, 38 sensors were tested in 25 patients with acute respiratory failure (e.g., the acute respiratory distress syndrome, complications after lung transplantation). Two conventional bench-top blood gas analysers (ABL 520 and ABL 300, Radiometer, Copenhagen) served as criterion standards. The mean differences (bias) and standard deviations (SD) of the differences (precision) were calculated according to the method of Bland and Altman [2]. In addition, linear regression analysis and correlation coefficients were calculated. The quality of blood pressure tracings was assessed using a grading system. RESULTS. The median sensor lifetime was 81.3 h; 869 blood samples (median 14 per sensor) were analysed for the comparison of continuous and conventional blood gas analysis. The ranges for measured parameters were: pH: 6.92 to 7.55; PCO2: 20 to 83 torr; PO2: 31 to 518 torr. The mean differences (SD) were: pH: -0.03 (0.03) or -0.4 (0.4)%; PCO2: -2.6 (4.1) torr or -6.9 (10.9)%; PO2: -3.4 (10.5) torr or -2.9 (7.0)%. The results of linear regression analysis and the correlation coefficients are depicted in Table 2. The mean grade of blood pressure tracings was satisfactory for the clinical setting. CONCLUSIONS. The continuous blood gas monitor is sufficiently accurate and precise for clinical use. Bias and precision are better than those known from former studies evaluating fibreoptic blood gas monitors under experimental conditions [7]. Cost-effectiveness was not an issue of this study.

The effects of comprehensive home physiotherapy and supervision on patients with ankylosing spondylitis--an 8-month followup

OBJECTIVE

Our previous randomized clinical trial showed a 4-month home physiotherapy program was effective for patients with ankylosing spondylitis. This followup study reports on 22 control patients who received the previously withheld treatment and 24 experimental patients who received followup treatment as needed.

METHODS

The primary outcome measure was spinal mobility measured by fingertip-to-floor distance using a portable measuring device specially designed and validated for this study.

RESULTS

Following treatment, fingertip-to-floor distance did not change in control patients (P2 = 0.145). Between 4 and 8 months, fingertip-to-floor distance did not change in experimental patients (P2 = 0.143); however, initial improvement achieved was maintained. The experimental group at 4 months was better than the control group at 8 months (P2 = 0.038).

CONCLUSION

The home physiotherapy treatment program must be delivered as rigorously as it was in the initial trial to be effective. The benefit from this treatment program can be maintained with very little intervention.

Leukocyte kinetics in pulmonary microcirculation: intravital fluorescence microscopic study

To determine the site of sequestration of leukocytes in the lung, we investigated the kinetics of fluorescently labeled erythrocytes and leukocytes in pulmonary arterioles, venules, and alveolar capillaries in vivo by using fluorescence videomicroscopy. The subpleural pulmonary microcirculation of the ventilated rabbit lung was visualized via a transparent window implanted into the right thoracic wall. Fluorescein isothiocyanate-labeled erythrocytes were administered intravenously, whereas leukocytes were labeled in vivo by intravenous injection of rhodamine 6G. Rolling and adherence of leukocytes on the surface of the vessel walls were observed in arterioles as well as in venules. The median velocity of nonadherent leukocytes was significantly higher in arterioles than in venules (84 +/- 12 vs. 15 +/- 3% of erythrocyte velocity, respectively). In alveolar capillaries the majority of leukocytes were retained at distinct sites for periods of 0.1 to > 5 s (median 0.61 s). The relative velocity of leukocytes moving in capillaries was comparable to that determined in arterioles (80 +/- 9% of erythrocyte velocity). These measurements indicate that leukocyte sequestration in the lung is governed by the retention of leukocytes in capillaries and by the interaction of leukocytes with microvascular endothelium of arterioles and venules. We propose that the kinetics of these phenomena determine the equilibrium between circulating and sequestered leukocytes.

[Quality control of platelet concentrates. Functional assessment of stored platelets in vitro]

Platelet concentrates transfused for correction of thrombocytopenia or reduced platelet function do not consistently improve primary haemostasis in the recipient. Insufficient therapeutic effects may be caused by impaired donor platelet function and by unfavourable donation and storage conditions, as well as by immunological interactions with the recipient blood. The present study was designed to investigate whether the effect of platelet transfusion on recipient platelet function can be predicted by in vitro methods. METHODS. Blood samples were taken from 12 thrombocytopenic patients before (20 ml, P0) and after (10 ml, P(vivo)) transfusion of one unit of platelets previously stored for 24-120 h in acid citrate dextrose. An additional sample was taken from the platelet concentrate (TK) immediately before transfusion. P0 was divided into two specimens and TK platelets were added to one of them (P(vitro) in order to obtain a platelet count similar to that in P(vivo). Bleeding time (BT) and bleeding volume (BV) of the samples P0, P(vivo) and P(vitro) were measured using the method of Kratzer and Born (Fig. 2); mean values were calculated for each sample from six measurements. Aggregability of TK platelets was determined in addition by aggregometry. In contrast to previous studies, physiological Ca2+ concentrations were restored and secondary haemostasis was inhibited by low-molecular-weight heparin (Fragmin P, Pfrimmer Kabi GmbH und Co. KG, Erlangen) in the platelet-rich plasma used for aggregometry. RESULTS. Platelet counts increased in all patients after transfusion (P(vivo) vs P0, Table 1) and were nearly identical in P(vitro) and P(vivo) (r = 0.94, P < 0.001; Fig. 3). Parameters of primary haemostasis were significantly improved by addition of platelets to P0 in vitro (BT P < 0.05, BV P < 0.01) as well as by platelet transfusion (BT P < 0.05, BV P < 0.01). Direct comparison of P(vitro) and P(vivo) yielded a very close correlation of BT (r = 0.88, P < 0.001) and BV (r = 0.89, P < 0.01) in both samples. Although aggregometry revealed decreasing platelet function with increased storage time, aggregability was considerably higher compared to previous studies of platelet concentrates stored for 2-5 days. CONCLUSION. A new technique has been developed which allows reliable prediction of the effect of platelet concentrates on primary haemostasis of the recipient by in vitro measurement of bleeding time and bleeding volume prior to transfusion using the method of Kratzer and Born.

[Monitoring blood coagulation in larger liver operations]

Bleeding is causally related to about 50% of postoperative deaths following liver resection. Main factors contributing to increased perioperative bleeding in liver surgery include surgical trauma, reduced activity of clotting factors and inhibitors due to impaired hepatic synthesis, low platelet count and poor platelet function as well as impaired clearance of activated clotting factors by the reticuloendothelial system of the liver (Kupffer cells). Hemostasis may be further impaired by transfusion of blood components, since citrate added for conservation is not adequately metabolized by the failing liver. Surgical bleeding leads to a loss of pro- and anticoagulatory factors as well as to activation of coagulation. Finally, hyperfibrinolysis induced by release of tissue plasminogen activator (t-PA, primary hyperfibrinolysis) and disseminated coagulation (secondary hyperfibrinolysis) contribute to increased bleeding. Therefore early diagnosis and treatment of coagulation disorders is of paramount importance during liver surgery. Screening parameters of hemostasis and fibrinolysis should be available on a 24-hour basis in centers performing liver surgery. Screening for disorders of secondary hemostasis includes evaluation of prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration and the activity of the most important inhibitor, antithrombin III (AT III). Thrombelastography is the leading method for diagnosis of hyperfibrinolysis, which can also be assessed by determination of D-dimer, fibrinogen and fibrin degradation products. Evaluation of primary hemostasis is frequently restricted to platelet count, which is only a rough parameter. In contrast, measurement of in vitro bleeding time and volume enables repeated quantification of platelet function in patients with impaired hemostasis.

Quantitative analysis of network architecture, and microhemodynamics in arteriolar vessel trees of the ventilated rabbit lung

An experimental model has been developed for morphometric and microhemodynamic analysis of discrete arteriolar networks in the ventilated lung. We implanted a transparent window into the right thoracic wall of anesthetized rabbits. Autologous red blood cells were labeled with FITC in vitro. Using a fluorescence video microscopic technique the vessels of superficial arteriolar networks were mapped and classified hierarchically. Networks were investigated under zone 2 conditions (alveolar > left atrial pressure) during continuous monitoring of macrohemodynamics. We comprehensively measured segment length, diameter (D) and branching pattern in the whole network. Microhemodynamic parameters (red blood cell flux (Frbc), red blood cell velocity (Vrbc) and microhematocrit (H mu) were determined in terminal branches. As a result of network analysis the branching rules were found to be similar to those found by cast techniques in human and cat lungs. In terminal arterioles D (21 +/- 4 microns), Frbc (1472 +/- 662 cells/s), Vrbc (863 +/- 250 microns/s) and H mu (0.28 +/- 0.067) were heterogeneously distributed. Geometric, as well as microhemodynamic parameters fitted best to a lognormal distribution. This study represents an example of in vivo analysis of discrete microvascular networks. The measurements in hierarchically equivalent segments of pulmonary arteriolar vessel trees have been shown to be appropriate for estimation of topological, geometrical and microhemodynamic heterogeneity in pulmonary arteriolar networks.

Minimum important difference between patients with rheumatoid arthritis: the patient's perspective

OBJECTIVE

To determine the point at which differences in clinical assessment scores on physical ability, pain and overall condition are sufficiently large to correspond to a subjective perception of a meaningful difference from the perspective of the patient.

METHODS

Forty patients with a diagnosis of rheumatoid arthritis participated in an evening of clinical assessment and one-on-one conversations with each other regarding their arthritic condition. The assessments included tender and swollen joint counts, clinician and patient global assessments, participant assessment of pain and the Health Assessment Questionnaire (HAQ) on physical ability. After each conversation, participants rated themselves relative to their conversational partner on physical ability, pain and overall condition. These subjective comparative ratings were compared to the differences of the individual clinical assessments.

RESULTS

In total there were 120 conversations. Generally participants judged themselves as less disabled than others. They rated themselves as "somewhat better" than their conversation partner when they had a (mean) 7% better score on the HAQ, 6% less pain, and 9% better global assessment. In contrast, they rated themselves as "somewhat worse" when they had a (mean) 16% worse score on the HAQ, 16% more pain, and 29% worse global assessment.

CONCLUSIONS

Patients view clinically important differences in an asymmetric manner. These results can provide guidance in interpreting results and planning clinical trials.

Monitoring der Blutgerinnung bei großen Leberoperationen

Nahezu die Hälfte der frühen Todesfälle nach Leberresektionen werden durch Blutungen verursacht. Neben dem chirurgischen Trauma sind vor allem Gerinnungsstörungen auf dem Boden präoperativ bestehender Einschränkungen der Leberfunktion für perioperative Blutungen verantwortlich. Typische hämostaseologische Auswirkungen von Leberfunktionsstörungen sind eine gestörte Synthese hepatogener Gerinnungsfaktoren und -inhibitoren, eine verminderte Thrombozytenzahl und -funktion sowie eine reduzierte Clearance-Funktion des hepatischen retikuloendothelialen Systems (RES, von Kupffersche Sternzellen) für aktivierte Gerinnungsfaktoren. Transfusion von Blutkomponenten kann die Koagulopathie verstärken, da das als Stabilisator enthaltene Zitrat nur unzureichend hepatisch metabolisiert wird. Chirurgische Blutungen führen zum Verlust pro- und antikoagulatorischer Faktoren sowie zur Gerinnungsaktivierung. Die Blutungsneigung wird noch verstärkt durch eine Hyperfibrinolyse, die durch Freisetzung von Tissue Plasminogen Activator (primäre Hyperfibrinolyse) sowie durch überschießende Aktivierung der plasmatischen Gerinnung (sekundäre Hyperfibrinolyse) induziert werden kann. Der frühzeitigen Diagnose und Therapie von Gerinnungsstörungen kommt daher bei chirurgischen Eingriffen an der Leber besondere Bedeutung zu. In operativen Zentren, an denen regelmäßig große Leberoperationen durchgeführt werden, sollte die Messung der wichtigsten Parameter zu jeder Zeit möglich sein. Hierzu gehören für die Erfassung der <i>sekundären Hämostase</i> die Prothrombinzeit (Quick-Test), die partielle Thromboplastinzeit (PTT), die Fibrinogenkonzentration sowie Antithrombin III als wichtigster Inhibitor. Indikatoren einer <i>Hyperfibrinolyse </i>sind D-Dimer, Fibrin- und Fibrinogen-Spaltprodukte; am sichersten wird sie jedoch mit Hilfe der Thrombelastographie diagnostiziert. Störungen der <i>primären Hämostase</i> können häufig nur sehr grob anhand der Thrombozytenzahl abgeschätzt werden. Die Messung der Blutungszeit und des Blutungsvolumens ex vivo ermöglicht hingegen eine exakte Quantifizierung der Thrombozytenfunktion und stellt eine wertvolle Ergänzung dar.