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Biomedical subjects

R Rossaint

Publications and source records attributed to R Rossaint.

At least 19 recordsLinked to original sources
PubMed2003

[Evidence-based medicine of the acute respiratory distress syndrome].

Different therapeutic approaches have recently been developed for treatment of acute respiratory distress syndrome (ARDS) with the aim of improving the outcome. The clinical significance and success of these therapies is variable with respect to evidence based medicine. Lung protective ventilation is accepted as a proven therapy and the use of positive end-expiratory pressure as well as spontaneous breathing during controlled ventilation are common therapies. High frequency ventilation, partial liquid ventilation and pulmonary surfactant application are still in the experimental stage. The prone position is recommended for severe cases of ARDS and the application of inhaled nitric oxide and of extracorporeal membrane oxygenation is established in specialized centers for patients with imminent hypoxia. But for the routine use of these three therapies a clear improvement in outcome could not demonstrated. Recommended drug therapy is limited to the administration of stress doses of corticosteroids and a special anti-inflammatory enteral diet.

Evidence-Based Medicine↗
PubMed2003

[Hyperpyrexia and rhabdomyolysis after ecstasy (MDMA) intoxication].

Abuse of 3,4-methylenedioxymethamphetamine (MDMA,Ecstasy) is still growing over the last years and reports of severe or even fatal complications, such as arrhythmias, hyperpyrexia, rhabdomyolysis, disseminated intravascular coagulopathy (DIC), acute renal or liver failure or brain oedema are also increasing. We report the case of a 21-year-old male who took a suicidal overdose of MDMA and subsequently developed severe hyperpyrexia (>43 degrees C/109.4 degrees F), rhabdomyolysis with an initial myoglobin level of 88,000 microg/l, disseminated intravascular coagulation (DIC) and beginning renal and liver failure. Infusing dantrolene 140 mg (2.5 mg/kg body weight) i.v. and using supportive cooling was effective in treating hyperpyrexia. To support renal function and diuresis we increased the intravenous fluid supply up to 5 l per day which led to a raised elimination of myoglobin, urea nitrogen and creatinine within 1 week. Hemodialysis was not necessary. DIC was treated according to laboratory parameters by supply of antithrombin (AT) III, fresh frozen plasma, prothrombin complex concentrates (PPSB) and continuous aprotinin 100,000 IE/h.

Acute Kidney Injury↗
PubMed2003

Breathing pattern and workload during automatic tube compensation, pressure support and T-piece trials in weaning patients.

BACKGROUND AND OBJECTIVE: Automatic tube compensation has been designed as a new ventilatory mode to compensate for the non-linear resistance of the endotracheal tube. The study investigated the effects of automatic tube compensation compared with breathing through a T-piece or pressure support during a trial of spontaneous breathing used for weaning patients from mechanical ventilation of the lungs. METHODS: Twelve patients were studied who were ready for weaning after prolonged mechanical ventilation (10.2 +/- 8.4 days) due to acute respiratory failure. Patients with chronic obstructive pulmonary disease were excluded. Thirty minutes of automatic tube compensation were compared with 30 min periods of 7 cmH2O pressure support and T-piece breathing. Breathing patterns and workload indices were measured at the end of each study period. RESULTS: During T-piece breathing, the peak inspiratory flow rate (0.65 +/- 0.20 L s(-1)) and minute ventilation (8.9 +/- 2.7L min(-1)) were lower than during either pressure support (peak inspiratory flow rate 0.81 +/- 0.25 L s(-1) minute ventilation 10.2 +/- 2.3 L min(-1), respectively) or automatic tube compensation (peak inspiratory flow rate 0.75 +/- 0.26L s(-1); minute ventilation 10.8 +/- 2.7 L min(-1)). The pressure-time product as well as patients' work of breathing were comparable during automatic tube compensation (pressure-time product 214.5 +/- 104.6 cmH2O s(-1) min(-1), patient work of breathing 1.1 +/- 0.4 J L(-1)) and T-piece breathing (pressure-time product 208.3 +/- 121.6 cmH2O s(-1) min(-1), patient work of breathing 1.1 +/- 0.4 J L(-1)), whereas pressure support resulted in a significant decrease in workload indices (pressure-time product 121.2 +/- 64.1 cmH2O s(-1) min(-1), patient work of breathing 0.7 +/- 0.4 J L(-1)). CONCLUSIONS: In weaning from mechanical lung ventilation, patients' work of breathing during spontaneous breathing trials is clearly reduced by the application of pressure support 7 cmH2O, whereas the workload during automatic tube compensation corresponded closely to the values during trials of breathing through a T-piece.

Adult↗
PubMed2003

Effect of isoflurane on monocyte adhesion molecule expression in human whole blood.

BACKGROUND: Recruitment of monocytes to inflamed tissue is a crucial step in the acute inflammatory reaction. Adherence of monocytes to endothelial cells followed by transmigration depends on monocyte surface adhesion molecules, inflammatory cytokines and chemoattractant chemokines. In the present study, we determined the effect of isoflurane on monocyte adhesion receptor expression in vitro. METHODS: Citrated whole blood was incubated for 60 min with either 0.5 or 1 MAC isoflurane. In unstimulated blood samples and after stimulation with N-formyl-methionyl-leucyl-phenylalanine (FMLP) monocyte cell-surface expression of the selectins PSGL-1 and L-selectin, and the beta2-integrins CD11a and CD11b were evaluated by flow cytometry. RESULTS: Isoflurane reduced significantly the expression of PSGL-1 on unstimulated monocytes, whereas the remaining selectins and beta2-integrins were not affected. At both concentrations, the FMLP-induced removal of PSGL-1 from the monocyte surface was increased. Furthermore, at 1 MAC isoflurane the FMLP-induced increase in CD11a expression was significantly inhibited. The surface expression of L-selectin and CD11b was not affected following exposure to isoflurane. CONCLUSION: Isoflurane increases the removal of the selectin PSGL-1 from the monocyte surface. Since PSGL-1 is important during the initial step of monocyte adhesion to endothelial P-selectin, the decrease in monocyte surface PSGL-1 may have profound effects on monocyte-endothelial interactions. Furthermore, the effects of isoflurane on monocyte adhesion molecule expression are different from those reported for neutrophils.

Anesthetics, Inhalation↗
PubMed2003

The effects of sevoflurane and desflurane in vitro on platelet-leukocyte adhesion in whole blood.

The interaction between platelets and leukocytes plays an important role in inflammatory and thrombotic processes. We investigated whether the volatile anaesthetics sevoflurane and desflurane alter the formation of platelet-leukocyte aggregates and the expression of P-selectin on platelets. Whole blood was incubated with 1 and 2 minimum alveolar concentration (MAC) sevoflurane or desflurane. Unstimulated and adenosine diphosphate, or thrombin receptor agonist peptide-6-stimulated samples were stained with fluorochrome-conjugated antibodies. The formation of platelet-leukocyte conjugates and the expression of P-selectin on platelets were measured using flow cytometry. Sevoflurane was found to enhance the binding of platelets to lymphocytes, neutrophils and monocytes, it also increased the expression of P-selectin on platelets especially in the stimulated samples. Desflurane decreased the percentage of lymphocyte-platelet, neutrophil-platelet and monocyte-platelet conjugates principally in unstimulated samples. The results show that these two volatile anaesthetics have differing effects on the formation of platelet-leukocyte conjugates in vitro. Sevoflurane also enhanced the expression of P-selectin on platelets.

Anesthetics, Inhalation↗
PubMed2003

Replacement of physiologically autoinhaled nitric oxide in intubated patients.

Autoinhaled nitric oxide (NO) is produced mainly in the upper airways. Orotracheal intubation disrupts the natural autoinhalation of NO from the naso- and oropharynx. The effect of disrupting and then replacing autoinhaled NO on arterial oxygenation was investigated in intubated patients. Two groups of nine patients without lung disease were examined during anaesthesia using an inspired oxygen fraction of 0.50. In both groups, the individually produced NO of the whole respiratory tract and the upper airways was determined. The amount of NO normally autoinhaled from the upper airways was replaced for 5 min after orotracheal intubation in one group. The amount of NO from the upper respiratory tract was 47+/-19 parts per billion (ppb) in the test group and the replaced NO concentration was 48+/-20 ppb. No significant increase in arterial oxygen tension could be detected during the replacement of the autoinhaled NO. Haemodynamic parameters remained unchanged. In the control group, the NO from the upper airways was 34+/-16 ppb. In contrast to the test group, it was not replaced after intubation. These findings suggest that in healthy subjects the autoinhalation of nitric oxide does not play an important role in arterial oxygenation during anaesthesia.

Aged↗
PubMed2002

Maximal flow rates and sieving coefficients in different plasmafilters: effects of increased membrane surfaces and effective length under standardized in vitro conditions.

In Europe, capillary membrane filters are the favored method for plasmapheresis and detoxification systems including a plasma separation unit. Using capillary membrane filters clearance depends on the filtration rate and the sieving coefficient (Qs) for the plasma substrates. We investigated whether the increase of the effective membrane surface of plasmafilters enables higher clearance rates than a small plasmafilter. Heparinized porcine blood (5 I.U./l) of healthy pigs was used for an in vitro circuit. Filter types used were from GAMBRO: n = 5 PF1000N (effective membrane surface: 0.15 m(2)), n = 4 PF2000N (0.35) and from ASAHI: n = 4 PLASMAFLO OP-05W (L) (0.5). Spontaneous hemolysis was chosen to indicate the individual threshold limit for maximal flow rates. Sieving coefficient was determined for ten parameters at lowest and highest blood flow (Qb) and filtration rates (Qf). PF1000N enabled maximal flow rates as high as PF2000N and PLASMAFLO (Qb/Qf in ml/min: 200/40). Qs for most substrates were similar between the filter types and the flow rates. Compared to PLASMAFLO, the filter type with the largest membrane surface, the PF1000N provided significantly better Qs for triglycerides and albumin and a trend for a better elimination of cholesterol, GGT, and LDH. The sieving properties of the PF2000N ranged between PF1000N and PLASMAFLO. Under standardized in vitro conditions, the larger plasmafilters tested did not improve the overall performance of the plasmapheresis procedure. Thus, enlargement of the membrane surface such as provided by two commercially available and clinically well-established plasmafilters could not be proven to enable higher clearance rates.

Animals↗
PubMed2002

[Analysis of the anesthesiologist's vigilance with an eye-tracking device. A pilot study for evaluation of the method under the conditions of a modern operating theatre].

INTRODUCTION: With the inclusion of new monitoring devices over the last two decades, the distribution of the anesthesiologists vigilance has changed which might influence the ergonomic profile of an optimal anesthesia workstation. The aim of this pilot study was the evaluation of an eyetracking device to analyze the vigilance distribution of an anesthesiologist during routine cases in an operating theatre of the 21st century. MATERIAL AND METHODS: Five anesthesiologist with different levels of training were followed during different types of surgery using a video camera-based eye-tracking system. The films were analyzed by an independent observer and rated according to defined regions of interest (ROI). Then typical scan-paths were identified and quantitatively analyzed. RESULTS: The eye-tracking studies proved to be technically of high quality but were time-consuming. Only few disturbances to the operating room (OR) personnel were recorded according to their subjective impressions but bias of behaviour due to the measurement procedure itself cannot be completely excluded. The vigilance of the anesthesiologist towards different factors was dependent on the level of professional training, the type of anesthesia and the type of surgery. Certain factors such as documentation (10-15%) or external disturbances (approximately 20%) proved to be relatively constant. Typical scan-paths could also be identified. CONCLUSION: Eye-tracking studies proved to be a suitable way to analyze the distribution of vigilance of anesthesiologists in a modern operating theatre. For further studies examining the influence of detailed modifications of the OR environment, a standardized study design with the same level of education, the same anesthesia technique and the same surgical procedure needs to be chosen.

Adult↗
PubMed2002

Comparison between nasal and intravenous desmopressin for the treatment of aminosalicylic acid-induced platelet dysfunction.

BACKGROUND AND OBJECTIVE: The study was conducted to compare the standard intravenous route with the intranasal route of desmopressin application and to establish the best time for initiating treatment with desmopressin with the use of the Born test and the PFA 100-Analyzer for monitoring the therapeutic effect. METHODS: Thirty healthy volunteers (ASA I) with no known bleeding disorder were randomly assigned to an intravenous or an intranasal group in a cross-over design fashion. After obtaining baseline values, the volunteers were given 500 mg aminosalicylic acid for 3 days. On day 4, platelet function tests were performed and desmopressin (0.3 microg kg(-1) body weight) was administered either intravenously or intranasally. Born tests (aggregation after stimulation with epinephrine and collagen) were conducted at 30 and 240 min, and PFA 100 bleeding time measurements were conducted at 30, 120 and 240 min after desmopressin administration. Wilcoxon signed rank sum tests or non-parametric ANOVA for repeated measures were used for statistical evaluation. RESULTS: All volunteers showed a marked decreased platelet function in the Born test (especially if stimulation with epinephrine was used) and an increased PFA 100 bleeding time after treatment with aminosalicylic acid. Platelet function was improved by intravenous as well as intranasal application of desmopressin (P < 0.001) after 30 min. The effect diminished after 4 h in both groups. CONCLUSIONS: Intravenous as well as intranasal desmopressin improved platelet function in healthy volunteers with aminosalicylic acid-induced platelet dysfunction at least 30 min after application. The effect lasts up to 4 h.

Administration, Intranasal↗
PubMed2002

Central anticholinergic syndrome in a child undergoing circumcision.

We describe one of the few pediatric cases of central anticholinergic syndrome (CAS) in an 8-year-old boy undergoing elective surgery. Deep sedation, inadequate response to stimuli and reduced muscular tone of the upper airway resulting in airway obstruction were the clinical manifestations of CAS. The symptoms resolved immediately after administration of physostigmine. This case illustrates the importance of considering central anticholinergic syndrome as a differential diagnosis in children if prolonged sedation after general anesthesia occurs.

Anesthesia↗
PubMed2002

Increased airway resistance during xenon anaesthesia in pigs is attributed to physical properties of the gas.

BACKGROUND: In this study we investigated the effects of the physical properties of xenon on respiratory mechanisms in pigs. METHODS: With institutional approval, 10 female pigs (mean 25.2 (SD 2.5) kg) were anaesthetized with thiopental, remifentanil, and pancuronium. Gas flow and pressure were recorded continuously at the proximal end of the tracheal tube during constant flow ventilation for control, with 100% oxygen (control), followed by 1.5% isoflurane in 70/30% nitrogen/oxygen, 1.0% isoflurane in 70/30% nitrous oxide/oxygen, and 70/30% xenon/oxygen in random order. Compliance (C) and resistance (R) were calculated using a single compartment model. Resistance was corrected for gas viscosities eta and also for densities pho and viscosities eta as (pho*eta)(1/2) to compare assumptions of laminar and mixed flow in the airways. RESULTS: With constant flow ventilation, xenon increases inspiratory pressure compared with other gas mixtures. There were no significant differences in resistance, corrected for laminar or mixed flow, between the gas mixtures. Xenon anaesthesia did not affect compliance. CONCLUSIONS: The increase in airway pressure observed with xenon anaesthesia is attributed completely to its higher density and viscosity. Therefore, determination of airway resistance must take into account the physical properties of the gas. Xenon does not exert any major effect on airway diameter.

Airway Resistance↗
PubMed2002

The influence of HES on the filtration properties of capillary membrane plasmaseparation.

Plasmaseparation is a treatment under discussion for critically ill patients, especially in sepsis and multiorgan failure. These patients receive a variety of different fluid substitutes, including hydroxyethylstarch (HES). HES is known to influence rheological properties, but nothing is known about the possible interactions between HES and the plamaseparation procedure. We used an in vitro plasmaseparation circuit with heparinized porcine blood. Before priming the system, 2 liters of blood were supplemented by adding 100 ml of either NaCl 0.9% or HES (n=6 in each group). We monitored the transmembrane (TMP) and the filtration pressure (PF) and measured free plasma hemoglobin (free Hb) and platelet counts before and after the two hours plasmaseparation procedure. The final transmembrane pressure was significantly higher with HES substitution. In the HES group we found negative filtration pressures from the very beginning with a significant further decrease toward the end of the experiments. A significant increase in free Hb and decrease in platelet counts were noted only in the HES group. Volume substitution with HES leads to impaired filtration properties and deteriorated hemocompatibility in in vitro plasmaseparation. Further studies have yet to evaluate whether or not the effects described also occur under clinical conditions.

Animals↗
PubMed2001

Lack of association between the -260 C-->T promoter polymorphism of the endotoxin receptor CD14 gene and the CD14 density of unstimulated human monocytes and soluble CD14 plasma levels.

OBJECTIVE: CD14 is a receptor for endotoxin and binds components of Gram-positive and Gram-negative bacteria. CD14-bearing monocytes respond to stimulation with the increased synthesis and release of cytokines. The recently described -260 C-->T promoter polymorphism of the CD14 gene has been found to be related to a risk of myocardial infarction. This study evaluated the role of this polymorphism in the expression of monocyte and soluble CD14. Moreover, the effect of the CD14 -260 genotypes for the ex vivo TNF-alpha response to endotoxin was analyzed in whole blood. PATIENTS AND PARTICIPANTS: Ninety-five healthy blood donors were studied. MEASUREMENTS AND RESULTS: CD14 -260 genotyping was performed by means of a real-time PCR with fluorescence labeled hybridization probes. CD14 expression on human monocytes (mCD14) was assessed by fluorescence-activated cell sorting analysis with anti-CD14 monoclonal antibodies. Plasma levels of soluble CD14 (sCD14) were measured by ELISA. The TNF-alpha synthesis was determined by chemiluminescence in whole blood after endotoxin stimulation. There were no differences in mCD14 density, sCD14 levels, or the tumor necrosis factor-alpha concentrations between individuals with the three different CD14 -260 genotypes CC, CT, and TT. CONCLUSIONS: The CD14 -260 polymorphism does not affect the CD14 expression of unstimulated circulating monocytes or soluble CD14 plasma levels.

Adult↗
PubMed2001

Effects of combined high-dose partial liquid ventilation and almitrine on pulmonary gas exchange and hemodynamics in an animal model of acute lung injury.

OBJECTIVES: To determine possible additive effects of combined high-dose partial liquid ventilation (PLV) and almitrine bismesylate (ALM) on pulmonary gas exchange and hemodynamics in an animal model of acute lung injury (ALI). DESIGN AND SETTING: Prospective, controlled animal study in an animal research facility of a university hospital. INTERVENTIONS: ALI was induced in 12 anesthetized and mechanically ventilated pigs by repeated wash-out of surfactant. After initiation of PLV with 30 ml/kg perfluorocarbon the animals were randomly assigned to receive either accumulating doses of ALM (0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 micrograms/kg per minute) for 30 min each (n = 6) or the solvent malic acid (n = 6). MEASUREMENT AND RESULTS: Pulmonary gas exchange and hemodynamics were measured at the end of each infusion period. Compared to ALI, PLV alone significantly increased arterial oxygen partial pressure (PaO2) and decreased venous admixture (QVA/QT) and mean pulmonary artery pressure (MPAP). Administration of ALM did not result in a further improvement in PaO2, QVA/QT or MPAP compared to PLV alone but decreased PaO2 and increased QVA/QT and MPAP when 16 micrograms/kg per min ALM was compared to PLV alone. CONCLUSIONS: In an animal model of surfactant depletion induced ALI the combined treatment of PLV and ALM induced no significant improvement in pulmonary gas exchange or hemodynamics when compared to PLV alone. Moreover, high-dose ALM significantly impaired gas exchange and pulmonary hemodynamics.

Almitrine↗
PubMed2001

Adsorption of xenobiotics to plastic tubing incorporated into dynamic in vitro systems used in pharmacological research--limits and progress.

Commonly used materials incorporated into dynamic culture systems typically show the feature of adsorption of lipophilic xenobiotics. Yet, this phenomenon is strongly limiting the use of dynamic culture models and ex vivo organ perfusions in pharmacological and toxicological research. The aim of the study was to characterize different materials with respect to their capacity for drug adsorption and to find methods or materials to reduce the loss of substrate by adsorption in order to improve the use of dynamic in vitro systems. The adsorption of different xenobiotics (lidocaine, midazolam, lormetazepam, phenobarbital, testosterone, ethoxyresoroufine) to tubes used in dynamic in vitro systems (polyvinyl-chloride, silicone) were investigated and compared to a new material (silicone-caoutchouc-mixture). In addition, the role of protein deposition onto the tubing was studied and it was investigated whether it was possible to reach saturation of the inner tube surface by pre-loading it with the test compound. We found that silicone tubes provided the highest comfort with respect to handling and reusability, but they also demonstrated the highest capacity for substrate adsorption. Polyvinyl-chloride was the second best in handling but also demonstrated a high complexity in its adsorption behavior. The silicone-caoutchouc-mixture reached acceptable experimental results with respect to its handling and demonstrated a very low capacity for substrate adsorption.

Adsorption↗
PubMed2001

Coagulation assessment in healthy pigs undergoing single xenon anaesthesia and combinations with isoflurane and sevoflurane.

BACKGROUND: With the introduction of new anaesthetics into clinical practice possible side effects of these novel anaesthetics have to be evaluated. This study was performed to clarify whether xenon or combinations of xenon with isoflurane or sevoflurane modify blood coagulation. METHODS: The study was performed in 20 healthy pigs which first underwent xenon anaesthesia (65 Vol%) and were then randomly assigned to combinations of xenon and isoflurane or sevoflurane at varying concentrations. During anaesthesia the following parameters were controlled: aPTT, PT, fibrinogen concentrations and thrombelastographic measurements. RESULTS: Xenon monoanaesthesia did not alter significantly any coagulation parameter. When isoflurane was introduced the aPTT showed a significant increase while fibrinogen concentration decreased. The introduction of sevoflurane led also to a decrease in fibrinogen concentration, while the aPTT was unchanged. These decreases in fibrinogen concentration were not accompanied by reduced maximal clot strength or elevated fibrinolysis evaluated by thrombelastography. Although the above-described changes were statistically significant, none of the parameters throughout the experiment exceeded the limits of normal values. CONCLUSION: In our study, xenon monoanaesthesia and combinations of xenon with isoflurane and sevoflurane did not lead to pathologic alterations in the measured coagulation parameters.

Anesthesia, Inhalation↗
PubMed2001

Magnesium as part of balanced general anaesthesia with propofol, remifentanil and mivacurium: a double-blind, randomized prospective study in 50 patients.

BACKGROUND AND OBJECTIVE: To test the hypothesis that magnesium sulphate reduces the amount of remifentanil needed for general anaesthesia in combination with propofol and mivacurium, we studied 50 patients undergoing elective pars plana vitrectomy in a double-blind, randomized prospective fashion. METHODS: Magnesium sulphate (50 mg kg(-1) body weight) or placebo (equal volume of NaCl) was given slowly intravenously after induction of anaesthesia with propofol 1-2 mg kg(-1). Anaesthesia was maintained with propofol (using electroencephalographic control), mivacurium (according to train-of-four monitoring of neuromuscular blockade) and remifentanil (according to heart rate and arterial pressure). RESULTS: We observed a significant reduction in remifentanil consumption from 0.14 to 0.09 microg kg(-1) min(-1) (P < 0.01). Mivacurium consumption was also markedly reduced from 0.01 to 0.008 mg kg(-1) min(-1) (P < 0.01), whereas propofol consumption remained unchanged. There was a trend towards lower postoperative pain scores, less pain medication requirements in 24 h after surgery and less postoperative nausea and vomiting in the magnesium group but not statistically significant. No side-effects were observed. CONCLUSION: We can recommend the use of magnesium sulphate as a safe and cost-effective supplement to a general anaesthetic regimen with propofol, remifentanil and mivacurium, although we cannot clearly distinguish between a mechanism as a (co)analgesic agent at the NMDA-receptor site or its properties as a sympatholytic. The effect of a single bolus dose of 50 mg kg(-1) on induction lasts for about 2 h. For longer cases, either a continuous infusion or repeated bolus doses might be necessary.

Adult↗