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Rolf Rossaint

Publications and source records attributed to Rolf Rossaint.

At least 37 records · Page 2Linked to original sources

Drotrecogin alfa (activated) for adults with severe sepsis and a low risk of death.

BACKGROUND: In November 2001, the Food and Drug Administration (FDA) approved drotrecogin alfa (activated) (DrotAA) for adults who had severe sepsis and a high risk of death. The FDA required a study to evaluate the efficacy of DrotAA for adults who had severe sepsis and a low risk of death. METHODS: We randomly assigned adult patients with severe sepsis and a low risk of death (defined by an Acute Physiology and Chronic Health Evaluation [APACHE II] score <25 or single-organ failure) to receive an intravenous infusion of placebo or DrotAA (24 microg per kilogram of body weight per hour) for 96 hours in a double-blind, placebo-controlled, multicenter trial. The prospectively defined primary end point was death from any cause and was assessed 28 days after the start of the infusion. In-hospital mortality within 90 days after the start of the infusion was measured, and safety information was collected. RESULTS: Enrollment in the trial was terminated early because of a low likelihood of meeting the prospectively defined objective of demonstrating a significant reduction in the 28-day mortality rate with the use of DrotAA. The study enrolled 2640 patients and collected data on 2613 (1297 in the placebo group and 1316 in the DrotAA group) at the 28-day follow-up. There were no statistically significant differences between the placebo group and the DrotAA group in 28-day mortality (17.0 percent in the placebo group vs. 18.5 percent in the DrotAA group; P=0.34; relative risk, 1.08; 95 percent confidence interval, 0.92 to 1.28) or in in-hospital mortality (20.5 percent vs. 20.6 percent; P=0.98; relative risk, 1.00; 95 percent confidence interval, 0.86 to 1.16). The rate of serious bleeding was greater in the DrotAA group than in the placebo group during both the infusion (2.4 percent vs. 1.2 percent, P=0.02) and the 28-day study period (3.9 percent vs. 2.2 percent, P=0.01). CONCLUSIONS: The absence of a beneficial treatment effect, coupled with an increased incidence of serious bleeding complications, indicates that DrotAA should not be used in patients with severe sepsis who are at low risk for death, such as those with single-organ failure or an APACHE II score less than 25.

APACHE↗

Respiratory compliance but not gas exchange correlates with changes in lung aeration after a recruitment maneuver: an experimental study in pigs with saline lavage lung injury.

INTRODUCTION: Atelectasis is a common finding in acute lung injury, leading to increased shunt and hypoxemia. Current treatment strategies aim to recruit alveoli for gas exchange. Improvement in oxygenation is commonly used to detect recruitment, although the assumption that gas exchange parameters adequately represent the mechanical process of alveolar opening has not been proven so far. The aim of this study was to investigate whether commonly used measures of lung mechanics better detect lung tissue collapse and changes in lung aeration after a recruitment maneuver as compared to measures of gas exchange METHODS: In eight anesthetized and mechanically ventilated pigs, acute lung injury was induced by saline lavage and a recruitment maneuver was performed by inflating the lungs three times with a pressure of 45 cmH2O for 40 s with a constant positive end-expiratory pressure of 10 cmH2O. The association of gas exchange and lung mechanics parameters with the amount and the changes in aerated and nonaerated lung volumes induced by this specific recruitment maneuver was investigated by multi slice CT scan analysis of the whole lung. RESULTS: Nonaerated lung correlated with shunt fraction (r = 0.68) and respiratory system compliance (r = 0.59). The arterial partial oxygen pressure (PaO2) and the respiratory system compliance correlated with poorly aerated lung volume (r = 0.57 and 0.72, respectively). The recruitment maneuver caused a decrease in nonaerated lung volume, an increase in normally and poorly aerated lung, but no change in the distribution of a tidal breath to differently aerated lung volumes. The fractional changes in PaO2, arterial partial carbon dioxide pressure (PaCO2) and venous admixture after the recruitment maneuver did not correlate with the changes in lung volumes. Alveolar recruitment correlated only with changes in the plateau pressure (r = 0.89), respiratory system compliance (r = 0.82) and parameters obtained from the pressure-volume curve. CONCLUSION: A recruitment maneuver by repeatedly hyperinflating the lungs led to an increase of poorly aerated and a decrease of nonaerated lung mainly. Changes in aerated and nonaerated lung volumes were adequately represented by respiratory compliance but not by changes in oxygenation or shunt.

Animals↗

Albumin and hydroxyethyl starch 130 kDa/0.4 improve filter clearance and haemocompatibility in haemo- and plasmafiltration--an in vitro study.

BACKGROUND: Apart from their standard applications, haemofiltration (HF) and plasmafiltration (PF) may provide helpful therapy for sepsis, multiple organ- and acute liver-failure. Some colloids cause either decreases or increases in blood cell agglomeration. We hypothesized that solutions which reduce cell aggregability may lead to both improved filter clearance and better haemocompatibility due to decreasing rates of clogged hollow fibres. METHODS: Heparinized porcine blood (5 IU/ml) was used in an in vitro circuit. The filter types tested were from GAMBRO: HF66D (effective membrane surface: 0.6 m2) and PF1000N (effective membrane surface: 0.15 m2). Albumin (ALB), hydroxyethyl starch (HES) 200/0.5, HES 130/0.4, gelatin (GEL) or normal saline (0.9%) were added to the blood (n = 6/group). Recirculation systems were run for 2 h. Spontaneous haemolysis and filter resistance >420 mmHg were selected as indications of maximal flow rates. Sieving coefficients were determined for 17 parameters at the lowest and highest blood flows and filtration rate. RESULTS: Based on the filter types used, supplementation of ALB and HES130/0.4 led to an improved filter clearance without increasing the number of clogged capillary membranes or causing impaired haemocompatibility. Sieving coefficients for most solutes were independent of volume substitute and flow rate. Haemocompatibility and filter clearance deteriorated after addition of HES200 or GEL to the blood. CONCLUSIONS: Under standardized in vitro conditions, we found that colloids which reduce cell aggregability cause improved HF- and PF-performance. This phenomenon may provide new options for higher clearances and may lead to new concepts in low dose anticoagulation.

Animals↗

Differential and additive effects of platelet-derived chemokines on monocyte arrest on inflamed endothelium under flow conditions.

Platelet-derived chemokines, such as regulated on activation, normal T expressed and secreted (RANTES; CC chemokine ligand 5), platelet factor 4 [PF4; CXC chemokine ligand 4 (CXCL4)], and epithelial neutrophil-activating protein 78 (ENA-78; CXCL5), or precursors, such as beta-thromboglobulin, which can be processed to neutrophil-activating protein-2 (NAP-2; CXCL7), may play an important role in monocyte recruitment during atherogenesis. Platelets can deposit chemokines on inflamed endothelium; however, little is known about differential or additive effects of platelet chemokines on monocyte arrest. Here, we demonstrate that preincubation of activated human microvascular endothelial cells (HMVECs) with RANTES, PF4, or NAP-2 but not ENA-78 dose-dependently increased surface immobilization and subsequent monocyte arrest in flow. RANTES was the most potent and efficient arrest chemokine. Pretreatment of HMVECs with beta-thromboglobulin enhanced monocyte arrest in the presence of cathepsin G generating NAP-2. Combined pretreatment of HMVECs with RANTES and PF4 at suboptimal concentrations synergistically increased arrest, and preincubation with chondroitinase ABC abrogated RANTES- and PF4-induced monocyte arrest. This was associated with reduced expression of chondroitin sulfate, RANTES, and PF4 on the HMVEC surface. Perfusion of HMVECs with platelets known to deposit RANTES and PF4 on the endothelial surface enhanced monocyte arrest, which was inhibited by Met-RANTES, chondroitinase, or a blocking antibody to PF4 but not to ENA-78. The relevance of platelet-derived chemokines was confirmed in adhesion assays with activated whole blood, where Met-RANTES and to a lesser extent, antibodies to PF4 and NAP-2 inhibited arrest of CD14-positive monocytes. Thus, multiple platelet-derived chemokines and processable precursors, which can be presented by specific endothelial proteoglycans, may contribute and cooperate differentially to induce monocyte recruitment.

Antibodies, Monoclonal↗

Evaluation of a new approach to implement structured, evidence-based emergency medical care in undergraduate medical education in Germany.

Since June 2002, revised regulations in Germany allow medical faculties to implement new curricular concepts. The medical faculty of the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen, Germany, decided to start a major reform experiment in winter 2003, focussing on an interdisciplinary integration of organs and organ systems such as the cardiovascular or respiratory system. Furthermore, students will have contact with patients at an early stage of their studies. Thus, re-organisation of course contents should lead to a chance to improve practical experience. With the public having the right to expect that physicians and all physicians in training possess a basic knowledge of emergency medical care and the necessary skills to manage acute problems, it was decided to start the first year of the Medical Reform Curriculum Aachen with 3 weeks interdisciplinary introduction into emergency medical care. The task consisted of defining interdisciplinary core objectives and the need to implement teaching and learning principles necessary for further education. Due to this, the content of this course should have practical relevance for the students concerning their practical experiences in the future. The result is an introductory course in emergency medical care in the first semester, coordinated with the lectures. Besides skill training on basics of emergency medical care (basic life support (BLS), early defibrillation), practical training in other lifesaving techniques (e.g., immobilisation skills) and basic principles of daily clinical care are included. In addition, personal safety and a standard algorithm for assessing the patient are covered by problem-based learning sessions. The course evaluation data clearly showed acceptance of the new approach and enhances possibilities of extending implementation of relevant topics concerning emergency medical care within the Medical Reform Curriculum Aachen.

Curriculum↗

Minimal instructions improve the performance of laypersons in the use of semiautomatic and automatic external defibrillators.

INTRODUCTION: There is evidence that use of automated external defibrillators (AEDs) by laypersons improves rates of survival from cardiac arrest, but there is no consensus on the optimal content and duration of training for this purpose. In this study we examined the use of semiautomatic or automatic AEDs by laypersons who had received no training (intuitive use) and the effects of minimal general theoretical instructions on their performance. METHODS: In a mock cardiac arrest scenario, 236 first year medical students who had not previously attended any preclinical courses were evaluated in their first study week, before and after receiving prespecified instructions (15 min) once. The primary end-point was the time to first shock for each time point; secondary end-points were correct electrode pad positioning, safety of the procedure and the subjective feelings of the students. RESULTS: The mean time to shock for both AED types was 81.2 +/- 19.2 s (range 45-178 s). Correct pad placement was observed in 85.6% and adequate safety in 94.1%. The time to shock after instruction decreased significantly to 56.8 +/- 9.9 s (range 35-95 s; P < or = 0.01), with correct electrode placement in 92.8% and adequate safety in 97%. The students were significantly quicker at both evaluations using the semiautomatic device than with the automatic AED (first evaluation: 77.5 +/- 20.5 s versus 85.2 +/- 17 s, P < or = 0.01; second evaluation: 55 +/- 10.3 s versus 59.6 +/- 9.6 s, P < or = 0.01). CONCLUSION: Untrained laypersons can use semiautomatic and automatic AEDs sufficiently quickly and without instruction. After one use and minimal instructions, improvements in practical performance were significant. All tested laypersons were able to deliver the first shock in under 1 min.

Adolescent↗

Xenon does not modify mivacurium induced neuromuscular block.

PURPOSE: The interaction between mivacurium and inhaled anesthetics is known, with the exception of xenon. We compared the pharmacodynamics of mivacurium during xenon anesthesia vs total iv anesthesia with propofol. METHODS: This randomized controlled trial was carried out in the Aachen University Hospital. Forty-two adult patients ASA I or II, aged 18 to 60 yr, were randomized to receive either xenon or propofol anesthesia. Anesthesia was induced with propofol and remifentanil in both groups (each n = 21). The xenon group received xenon via face mask until an end-expiratory concentration of 60% was reached for one minute. Meanwhile, the acceleromyograph was calibrated and a train-of-four stimulation of the adductor pollicis muscle was started. After stabilization of the signal for five minutes, a single bolus of 0.16 mg.kg-1 mivacurium was injected. Anesthesia was maintained with xenon and remifentanil or with propofol and remifentanil. RESULTS: There were no significant differences between groups with respect to onset time (xenon 180 +/- 64 vs propofol 195 +/- 77 sec; P = 0.39), duration (xenon 16.18 +/- 4.97 vs propofol 15.68 +/- 6.17 min; P = 0.73), recovery index (xenon 5.63 +/- 2.48 vs propofol 5.73 +/- 2.12 min; P = 0.42) and clinical recovery (xenon 8.75 +/- 2.57 vs propofol 9.28 +/- 2.28 min; P = 0.22). CONCLUSION: We conclude that the neuromuscular blocking effects of mivacurium are similar when given during propofol vs xenon anesthesia.

Adolescent↗

S-100 protein and neurohistopathologic changes in a porcine model of acute lung injury.

BACKGROUND: Survivors of acute respiratory distress syndrome exhibit neuropsychological sequelae that might be attributable to hippocampal damage. The authors sought to determine the effects of hypoxemia in a pig model of acute lung injury on the hippocampal region and the release of S-100 protein in comparison to a control group in which hypoxemia was induced by reducing the inspired oxygen fraction. METHODS: Hypoxemia was induced in 14 female pigs by repeated lung lavages (lung injury group; n = 7) or by reducing the inspired oxygen fraction (hypoxia-only group; n = 7). Hemodynamic variables, gas exchange, and serum concentrations of S-100 protein were measured at baseline, after induction of acute lung injury, and subsequently for 12 h. Animals were euthanized, and the brains were removed for histopathologic examination. RESULTS: Comparable blood gases were seen in both groups. Serum S-100 protein concentrations were comparable for both groups at baseline. At all other time points, S-100 concentrations were significantly higher in the lung injury group. Neuropathologic examination showed basophilic and shrunken neurons of the pyramidal cell layer in the hippocampal CA1 subregion of all pigs in the lung injury group. Few abnormalities were seen in the hypoxia-only group. CONCLUSIONS: The same degree of hypoxemia induced in a lavage model of acute lung injury results in greater brain damage assessed by S-100 protein and histopathologic findings when compared to a group in which hypoxemia at the same degree was induced by reducing the inspired oxygen fraction. This suggests that acute lung injury leads to neuropathologic changes independent of hypoxemia.

Animals↗

Neurological emergencies as causes of accidents.

OBJECTIVES: A large number of people throughout Europe are involved in accidents every year. Neurological emergencies as the underlying cause of accidents are poorly investigated. This retrospective chart review study was performed to evaluate the incidence of such events. METHODS: We retrospectively screened the records of the database of our physician-staffed emergency medical service for a 2-year period of time for patients involved in accidents suspicious of having had a neurological incident leading to the accident. The admission diagnoses of these records were compared with the final diagnosis as taken from the hospital records. Additional demographical (gender, age, time of accident) and medical (Glasgow Coma Scale, Injury Severity Score, National Advisory Committee on Aeronautics-Score) data were evaluated and analyzed. RESULTS: A total of 1545 records associated with accidents were screened, identifying 110 (7.1%) cases eligible for analysis. Fifty-four patients had seizure (49.1%), 7 stroke (6.3%) and 2 suffered from intracerebral hemorrhage (1.8%). The admission diagnosis made by the physician was confirmed in 91.8% of the cases. Accidents with concomitant neurological event happened significantly more frequent between 9 and 12 am. No differences were observed in demographic or medical data for patients with acute neurological event prior to the accident. CONCLUSION: Neurological emergencies, particularly epilepsy, stroke and intracerebral hemorrhage are causes of accidents which have to be considered more often than expected and happen most frequently in the morning. Other demographical and medical data provide no additional information for emergency medical personnel to specifically identify such patients. Nevertheless, emergency physicians seem to be highly skilled in finding the correct diagnosis.

Accidents↗

Recombinant factor VIIa as adjunctive therapy for bleeding control in severely injured trauma patients: two parallel randomized, placebo-controlled, double-blind clinical trials.

BACKGROUND: Uncontrolled bleeding is a leading cause of death in trauma. Two randomized, placebo-controlled, double-blind trials (one in blunt trauma and one in penetrating trauma) were conducted simultaneously to evaluate the efficacy and safety of recombinant factor VIIa (rFVIIa) as adjunctive therapy for control of bleeding in patients with severe blunt or penetrating trauma. METHODS: Severely bleeding trauma patients were randomized to rFVIIa (200, 100, and 100 microg/kg) or placebo in addition to standard treatment. The first dose followed transfusion of the eighth red blood cell (RBC) unit, with additional doses 1 and 3 hours later. The primary endpoint for bleeding control in patients alive at 48 hours was units of RBCs transfused within 48 hours of the first dose. RESULTS: Among 301 patients randomized, 143 blunt trauma patients and 134 penetrating trauma patients were eligible for analysis. In blunt trauma, RBC transfusion was significantly reduced with rFVIIa relative to placebo (estimated reduction of 2.6 RBC units, p = 0.02), and the need for massive transfusion (>20 units of RBCs) was reduced (14% vs. 33% of patients; p = 0.03). In penetrating trauma, similar analyses showed trends toward rFVIIa reducing RBC transfusion (estimated reduction of 1.0 RBC units, p = 0.10) and massive transfusion (7% vs. 19%; p = 0.08). Trends toward a reduction in mortality and critical complications were observed. Adverse events including thromboembolic events were evenly distributed between treatment groups. CONCLUSION: Recombinant FVIIa resulted in a significant reduction in RBC transfusion in severe blunt trauma. Similar trends were observed in penetrating trauma. The safety of rFVIIa was established in these trauma populations within the investigated dose range.

Adult↗

Impact of inverse plasma filtration on complement activation in porcine blood.

During extracorporeal circulation, activation of the complement system as a bioincompatibility reaction upon contact with artificial surfaces is well known. This may induce adverse effects for the patient as well as for the bioreactor when using a hybrid liver support system. At present, the achievable clearance rates in hybrid liver support systems are restricted by the limitations of blood flow through the capillaries of the plasma filter. In order to enhance clearance rates it is desirable to develop a high-flow plasma separation unit in which the activation of the complement system is as low as possible. Conventional plasma filters operating in normal and in inverse (blood flow around the capillaries and the capillary lumen serving as plasma compartment) modes were investigated applying an in vitro circuit (n = 4 in each group). For this purpose heparinized porcine blood was used. Complement activation was measured as generation of the soluble membrane attack complex, SC5b-9. With a normal flow mode the maximum achievable filtration rates varied from 25 to 40 mL/min, whereas the maximal filtration rates with an inverse flow mode varied from 40 to 100 mL/min. While these values were significantly higher than those with regularly operating plasma filters, there was no significant difference between normal and inverse mode in the production of SC5b-9. We conclude that the outer surface of the investigated conventional plasma filtration membranes is suitable for an inverse mode and does not lead to an excessive activation of the complement system upon dynamic blood contact. Thus, the inversion of the blood and the plasma compartments may be a possible way forward in the development of a high-flow plasma separation filter.

Animals↗

Epinephrine enhances platelet-neutrophil adhesion in whole blood in vitro.

Previous studies showed that alpha- or beta-adrenoceptor stimulation by catecholamines influenced neutrophil function, cytokine liberation, and platelet aggregability. We investigated whether adrenergic stimulation with epinephrine also alters platelet-neutrophil adhesion. This might be of specific interest in the critically ill, because the increased association of platelets and neutrophils has been shown to be of key importance in inflammation and thrombosis. For this purpose, whole blood was incubated with increasing concentrations of epinephrine (10 nM, 100 nM, and 1 microM). To distinguish receptor-specific effects, a subset of samples was incubated with propranolol (10 microM) or phentolamine (10 microM) before exposure to epinephrine. After incubation, another subset of samples was also stimulated with 100 nM of N-formyl-methionyl-leucyl-phenylalanine. All samples were stained, and platelet-neutrophil adhesion and CD45, L-selectin, CD11b, P-selectin glycoprotein ligand-1, glycoprotein IIb/IIIa, and P-selectin expression were measured by two-color flow cytometry. Epinephrine significantly enhanced platelet-neutrophil adhesion and P-selectin and glycoprotein IIb/IIIa expression on platelets. CD11b and L-selectin expression on unstimulated neutrophils remained unchanged, whereas N-formyl-methionyl-leucyl-phenylalanine-induced upregulation of CD11b and downregulation of L-selectin were suppressed by epinephrine. beta-Adrenergic blockade before incubation with epinephrine increased platelet-neutrophil aggregates and adhesion molecule expression (CD11b, P-selectin, and glycoprotein IIb/IIIa) even further. These results demonstrate that epinephrine enhances platelet-neutrophil adhesion. The alpha-adrenergic receptor-mediated increase in P-selectin and glycoprotein IIb/IIIa expression on platelets may contribute substantially to this effect. Our study shows that inotropic support enhances the platelet-neutrophil interaction, which might be crucial for critically ill patients.

Adrenergic Agonists↗

Repeated generation of the pulmonary pressure-volume curve may lead to derecruitment in experimental lung injury.

OBJECTIVE: Measurements from the pulmonary pressure-volume (PV) curve have been proposed to adjust ventilator settings. We investigated the effects of repeated construction of an inflation PV curve implemented in a standard ventilator on recruitment or derecruitment in acutely injured lungs. DESIGN AND SETTING: Prospective experimental animal study in eight anesthetized and mechanically ventilated pigs. INTERVENTIONS: Acute lung injury was induced by lung lavage and animals were ventilated in volume controlled mode with PEEP 10 cmH(2)O. The PV curve was constructed five times repeatedly by constant pressure rise, after which ventilation with the preset PEEP was resumed immediately. Studies of hemodynamics, lung mechanics, blood gases and computed tomography were carried out before and after maneuvers. MEASUREMENTS AND RESULTS: Derecruitment was assessed as an increase in nonaerated lung volume (V(NON)), and V(PEEP) was the end-expiratory volume difference between PEEP and ZEEP. There was a significant decrease in PaO(2) from 90.4+/-33.3 to 70.9+/-36.3 mmHg and a rise in venous admixture from 47.8+/-12.7 to 59.1+/-16.6%. V(PEEP) was reduced from 244 to 202 ml. A corresponding decrease in normally aerated lung volume was observed, while regression analysis revealed increase in V(NON) depending on the amount of preexisting atelectasis. CONCLUSIONS: Repeated generation of the PV curve with a readily available tool resulted in worsened oxygenation. Derecruitment of the lungs occurred with loss of PEEP at the start of the maneuver, which could not be recovered by a maximum inflation pressure of 40 cmH(2)O. Repeated use of the investigated tool should be cautioned, and users should consider measures to preserve aerated lung volumes.

Animals↗

Reduced colonization and infection with miconazole-rifampicin modified central venous catheters: a randomized controlled clinical trial.

OBJECTIVE: Central venous catheters (CVC) are a major cause of nosocomial bloodstream infections. Catheters modified with miconazole and rifampicin that constantly and slowly release antimicrobial substances are assumed to be beneficial in reducing rates of colonization and catheter-related infections. DESIGN AND SETTING: Prospective controlled non-blinded randomized clinical trial in two German university hospitals. PATIENTS: 223 adult inpatients with CVC between October 2000 and February 2002. Baseline characteristics, APACHE II score and therapeutic interventions were comparable. INTERVENTION: Randomization to receive either a miconazole and rifampicin modified catheter (n=118) or a standard triple-lumen CVC (n=105). MEASUREMENTS, DEFINITIONS: Microbiological evaluation was done after CVC removal. A catheter was considered colonized if growth of > or =15 cfu was found by semi-quantitative roll-plate technique from a proximal or distal catheter segment. A catheter-related infection (CRI) was defined as a colonized catheter with local signs of inflammation. A catheter-related bloodstream infection (CR-BSI) was defined as a colonized catheter with isolation of the same organism from the patient's blood with accompanying clinical signs of infection. RESULTS: A colonization of CVC was observed in six patients (5.1%) with a modified catheter and 38 patients (36.2%) with a standard catheter (P < 0.001). Five patients in the modified group (4.2%) and 18 in the standard group (17.1%) developed CRI (P=0.002). One assumed CR-BSI was detected in the standard group, with none in the modified group. No adverse effects related to the modified catheters and no antimicrobial resistance were observed. CONCLUSION: CVC supersaturated with miconazole and rifampicin were associated with a significantly lower risk for catheter colonization and catheter-related infections compared to standard catheters.

Adolescent↗

Ventilation with biphasic positive airway pressure in experimental lung injury. Influence of transpulmonary pressure on gas exchange and haemodynamics.

OBJECTIVE: We investigated whether improvement in ventilation perfusion (.V(A)/.Q) distribution during mechanical ventilation using biphasic positive airway pressure (BIPAP) with spontaneous breathing may be attributed to an effectively increased transpulmonary pressure (P(TP)) and can also be achieved by increasing P(TP) during controlled ventilation. DESIGN: In 12 pigs with saline lavage-induced lung injury we compared the effects of BIPAP to pressure-controlled ventilation with equal airway pressure (PCV(AW)) or equal transpulmonary pressure (PCV(TP)) on V(A)/.Q distribution assessed by the multiple inert gas elimination technique (MIGET). SETTING: Animal laboratory study. MEASUREMENTS AND RESULTS: Intrapulmonary shunt was 33+/-11% during BIPAP, 36+/-10% during PCV(AW) and 33+/-15% during PCV(TP) ( p= n.s.). BIPAP resulted in higher PaO(2) than PCV(AW) (188+/-83 versus 147+/-82 mmHg, p < 0.05), but not than PCV(TP) (187+/-139 mmHg). Oxygen delivery was significantly higher during BIPAP (530+/-109 ml/min) versus 374+/-113 ml/min during PCV(AW) and 353+/-93 ml/min during PCV(TP) ( p < 0.005). Tidal volume with PCV(TP) increased to 11.9+/-2.3 ml/kg, compared to 8.5+/-0.8 with BIPAP and 7.6+/-1.4 with PCV(AW) ( p <0.001) and cardiac output decreased to 3.5+/-0.6 l/min (BIPAP 4.9+/-0.8 and PCV(AW) 3.9+/-0.8, p<0.006). CONCLUSIONS: In experimental lung injury, BIPAP with preserved spontaneous breathing was effective in increasing regional P(TP), since pressure-controlled ventilation with the same P(TP) resulted in similar gas exchange effects. However, PCV(TP) caused increased airway pressures and tidal volumes, whereby, with BIPAP, less depression of oxygen delivery and cardiac output were observed. BIPAP could be useful in maintaining pulmonary gas exchange and slightly improving oxygenation without interfering with circulation as strongly as PCV does.

Animals↗

Temperature-independent Inhibition of L-type calcium currents by halothane and sevoflurane in human atrial cardiomyocytes.

BACKGROUND: Cardiac L-type calcium currents (ICa,L) are affected by volatile anesthetics, possibly contributing to their side effects. Actions of anesthetics on ion channels are usually studied in vitro at room temperature. However, the solubility of anesthetic gases as well as ICa,L are markedly sensitive to the study temperature. Therefore, temperature-dependent effects of halothane and sevoflurane on cardiac ICa,L were analyzed. METHODS: ICa,L were studied at 21 degrees C and 36 degrees C with the patch clamp technique in isolated human atrial cardiomyocytes. Concentrations of anesthetics brought into solution by gassing at both temperatures were determined with gas chromatography. RESULTS: The aqueous concentrations of halothane and sevoflurane were linearly related to their concentration in the gas phase (1 to 3 minimum alveolar concentration [MAC]). At 21 degrees C, the slope of this relation was 0.52 and 0.12 mm/vol % for halothane and sevoflurane, respectively, and decreased at 36 degrees C to 0.29 and 0.09 mm/vol %, respectively. ICa,L displayed significantly higher current amplitudes at 36 degrees C than at 21 degrees C and significantly accelerated time-dependent inactivation. Halothane (1-2 MAC) and sevoflurane (1-3 MAC) evoked stronger inhibitions of ICa,L at 21 degrees C than at 36 degrees C. In spite of different temperature-dependent current amplitudes, the fractional (percent) inhibition of ICa,L showed the same linear relationship to the concentrations of halothane and sevoflurane in the bath medium at both temperatures, as revealed from present and previous experiments. CONCLUSIONS: Inhibition of ICa,L by halothane and sevoflurane is determined by the aqueous concentration of the anesthetics, independently of the temperature. Increased solubility may explain the stronger effects of the anesthetics at lower temperatures.

Algorithms↗

Ventilation-perfusion distribution related to different inspiratory flow patterns in experimental lung injury.

UNLABELLED: In acute lung injury (ALI), controlled mechanical ventilation with decelerating inspiratory flow (.V(dec)) has been suggested to improve oxygenation when compared with constant flow (.V(con)) by improving the distribution of ventilation and perfusion (.V(A)/.Q). We performed the present study to test this hypothesis in an animal model of ALI. Furthermore, the effects of combined decelerating and constant flow (Vdot;(deco)) were evaluated. Thus, 18 pigs with experimental ALI were randomized to receive mechanical ventilation with either .V(con), .V(dec) or a fixed combination of both flow wave forms (.V(deco)) at the same tidal volume and positive end-expiratory pressure level for 6 h. Hemodynamics, gas exchange, and .V(A)/.Q distribution were determined. The results revealed an improvement of oxygenation resulting from a decrease of pulmonary shunt within each group (P < 0.05). However, blood flow to lung areas with a normal .V(A)/.Q distribution increased only during ventilation with .V(con) (P < 0.05). Accordingly, PaO(2) was higher with .V(con) than with .V(dec) and .V(deco) (P < 0.05). We conclude that contrary to the hypothesis, .V(con)provides a more favorable .V(A)/.Q distribution, and hence better oxygenation, when compared with .V(dec) and .V(deco) in this model of ALI. IMPLICATIONS: In acute lung injury, mechanical ventilation with decelerating flow has been suggested to improve ventilation-perfusion distribution when compared with constant flow. We tested this hypothesis in an animal model. Contrary to the hypothesis, we found a more favorable ventilation-perfusion distribution during constant flow when compared with decelerating flow.

Airway Resistance↗

Xenon and isoflurane differentially modulate lipopolysaccharide-induced activation of the nuclear transcription factor KB and production of tumor necrosis factor-alpha and interleukin-6 in monocytes.

UNLABELLED: Anesthetics are known to interfere with the production of inflammatory cytokines. In this study, we investigated the effect of xenon and isoflurane on the lipopolysaccharide (LPS)-induced activation of the nuclear transcription factor (NF)-kappaB and production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 in vitro. Whole blood was incubated with LPS in the absence or presence of the either xenon (30 and 60 Vol%) and isoflurane (1 and 2 minimum alveolar anesthetic concentration [MAC]). After 4 h, TNF-alpha and IL-6 were assayed in the supernatant. Involvement of NF-kappaB was investigated using isolated monocytes from the blood samples. Whole-cell lysates were prepared, and binding of the NF-kappaB p50 and p65 subunit to its target DNA were measured with an enzyme-linked immunosorbent assay-based NF-kappaB kit. LPS-induced production of TNF-alpha and IL-6 as well as activation of NF-kappaB were significantly increased in the presence of xenon compared with controls. In contrast, isoflurane inhibited the activation of NF-kappaB, which was associated with a decreased production of TNF-alpha and IL-6. Our results demonstrate that xenon and isoflurane have opposite effects on the LPS-induced production of TNF-alpha and IL-6. Furthermore, xenon increases, whereas isoflurane inhibits the activation of NF-kappaB, providing a possible molecular mechanism for the different effects on monocyte TNF-alpha and IL-6 production. IMPLICATIONS: This study has shown that monocytes respond to lipopolysaccharide (LPS) in the presence of xenon with an increased activation of nuclear transcription factor (NF)-kappaB, whereas isoflurane inhibits LPS-induced activation of NF-kappaB. These findings suggest a possible molecular mechanism for the different effects of both anesthetics on monocyte tumor necrosis factor-alpha and interleukin-6 production.

Anesthetics, Inhalation↗