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Biomedical subjects

Michael Sander

Publications and source records attributed to Michael Sander.

At least 19 recordsLinked to original sources
PubMed2006

Intervention at the level of the neuroendocrine-immune axis and postoperative pneumonia rate in long-term alcoholics.

RATIONALE: Postoperative pneumonia is three to four times more frequent in patients with alcohol use disorders followed by prolonged intensive care unit (ICU) stay. Long-term alcohol use leads to an altered perioperative hypothalamus-pituitary-adrenal (HPA) axis and immunity. OBJECTIVES: The aim of this study was to evaluate HPA intervention with low-dose ethanol, morphine, or ketoconazole on the neuroendocrine-immune axis and development of postoperative pneumonia in long-term alcoholic patients. METHODS: In this randomized, double-blind controlled study, 122 consecutive patients undergoing elective surgery for aerodigestive tract cancer were included. Long-term alcohol use was defined as consuming at least 60 g of ethanol daily and fulfilling the Diagnostic and Statistical Manual of Mental Disorders IV criteria for either alcohol abuse or dependence. Nonalcoholic patients were included but only as a descriptive control. Perioperative intervention with low-dose ethanol (0.5 g/kg body weight per day), morphine (15 mug/kg body weight per hour), ketoconazole (200 mg four times daily), and placebo was started on the morning before surgery and continued for 3 d after surgery. Blood samples to analyze the neuroendocrine-immune axis were obtained on the morning before intervention and on Days 1, 3, and 7 after surgery. MEASUREMENTS AND MAIN RESULTS: In long-term alcoholic patients, all interventions decreased postoperative hypercortisolism and prevented impairment of the cytotoxic T-lymphocyte type 1:type 2 ratio. All interventions decreased the pneumonia rate from 39% to a median of 5.7% and shortened intensive care unit stay by 9 d (median) compared with the placebo-treated long-term alcoholic patients. CONCLUSIONS: Intervention at the level of the HPA axis altered the immune response to surgical stress. This resulted in decreased postoperative pneumonia rates and shortened intensive care unit stay in long-term alcoholic patients.

APACHE↗
PubMed2006

Conditioning-annealing studies of natural organic matter solids linking irreversible sorption to irreversible structural expansion.

The assumption of reversibility underpins the sorption term in current models dealing with the fate and impact of organic compounds in the environment, yet experimentally sorption of organic compounds in soils and sediments often shows "irreversible" behaviors such as hysteresis and the conditioning effect (enhanced repeat sorption). The objective of this study was to test whether a glassy polymer irreversibility model applies to natural organic matter (NOM) solids. Irreversible sorption in polymers is believed to be caused by irreversible expansion and creation of internal micropores by penetrating molecules, leading to enhanced affinity during desorption or subsequent resorption. Using chlorobenzene as a conditioning agent and polychlorinated benzenes as test compounds in a second sorption step, we observed conditioning effects for a peat soil, a soil humic acid, and a model glassy polymer, poly- (vinyl chloride), but not for a model rubbery polymer, poly- (ethylene). The conditioning effect for the two natural solids, probed bythe enhancement in the sorption distribution coefficient of 1,2,4-trichlorobenzene, relaxed upon sample annealing between 45 and 91 degrees C in a manner similar to the relaxation of free volume and enthalpy of glassy polymers. Relaxation of the conditioning effect in the NOM solids depended on annealing temperature and, at a given temperature, followed a double additive exponential rate law with a nonzero constant term descriptive of the final state that depends inversely on temperature. At environmentally relevant temperatures, the conditioning effect may "never" completely relax. The results provide compelling evidence for the glassy, nonequilibrium nature of natural organic matter solids and for irreversible structural expansion as a cause of irreversible sorption.

Adsorption↗
PubMed2006

[Implementation of standard operating procedures for the initial empirical antimicrobial therapy for adults--a new computer program at the University Hospital Charité].

Nowadays 40-50 % of the patients receive inappropriate antibiotic treatment. Evidence based recommendations are not considered and there is an increasing burden of resistant pathogens. Therefore, standard operating procedures (SOPs) should be implemented considering guidelines and resistant species in the specific ICU. The authors developed algorithms and generated a user friendly computer program available for all ICU physicians all the time.

Algorithms↗
PubMed2006

The impact of an hematocrit of 20% during normothermic cardiopulmonary bypass for elective low risk coronary artery bypass graft surgery on oxygen delivery and clinical outcome--a randomized controlled study [ISRCTN35655335].

INTRODUCTION: Cardiopulmonary bypass (CPB) induces hemodilutional anemia, which frequently requires the transfusion of blood products. The objective of this study was to evaluate oxygen delivery and consumption and clinical outcome in low risk patients who were allocated to an hematocrit (Hct) of 20% versus 25% during normothermic CPB for elective coronary artery bypass graft (CABG) surgery. METHODS: This study was a prospective, randomized and controlled trial. Patients were subjected to normothermic CPB (35 to 36 degrees C) and were observed until discharge from the intensive care unit (ICU). Outcome measures were calculated whole body oxygen delivery, oxygen consumption and clinical outcome. A nonparametric multivariate analysis of variance for repeated measurements and small sample sizes was performed. RESULTS: In a total of 54 patients (25% Hct, n = 28; 20% Hct, n = 26), calculated oxygen delivery (p = 0.11), oxygen consumption (p = 0.06) and blood lactate (p = 0.60) were not significantly different between groups. Clinical outcomes were not different between groups. CONCLUSION: These data indicate that an Hct of 20% during normothermic CPB maintained calculated whole body oxygen delivery above a critical level after elective CABG surgery in low risk patients. The question of whether a transfusion trigger in excess of 20% Hct during normothermic CPB is still supported requires a larger prospective and randomized trial.

Adult↗
PubMed2006

Comparison of uncalibrated arterial waveform analysis in cardiac surgery patients with thermodilution cardiac output measurements.

INTRODUCTION: Cardiac output (CO) monitoring is indicated only in selected patients. In cardiac surgical patients, perioperative haemodynamic management is often guided by CO measurement by pulmonary artery catheterisation (COPAC). Alternative strategies of CO determination have become increasingly accepted in clinical practice because the benefit of guiding therapy by data derived from the PAC remains to be proven and less invasive alternatives are available. Recently, a device offering uncalibrated CO measurement by arterial waveform analysis (COWave) was introduced. As far as this approach is concerned, however, the validity of the CO measurements obtained is utterly unclear. Therefore, the aim of this study was to compare the bias and the limits of agreement (LOAs) (two standard deviations) of COWave at four specified time points prior, during, and after coronary artery bypass graft (CABG) surgery with a simultaneous measurement of the gold standard COPAC and aortic transpulmonary thermodilution CO (COTranspulm). METHODS: Data from 30 patients were analysed during this prospective study. COPAC, COTranspulm, and COWave were determined in all patients at four different time points prior, during, and after CABG surgery. The COPAC and the COTranspulm were measured by triple injection of 10 ml of iced isotone sodium chloride solution into the central venous line of the PAC. Measurements of COWave were simultaneously taken at these time points. RESULTS: The overall correlation showed a Spearman correlation coefficient between COPAC and COWave of 0.53 (p < 0.01) and 0.84 (p < 0.01) for COPAC and COTranspulm. Bland-Altman analysis showed a mean bias and LOAs of 0.6 litres per minute and -2.2 to +3.4 litres per minute for COPAC versus COWave and -0.1 litres per minute and -1.8 to +1.6 litres per minute for COPAC versus COTranspulm. CONCLUSION: Arterial waveform analysis with an uncalibrated algorithm COWave underestimated COPAC to a clinically relevant extent. The wide range of LOAs requires further evaluation. Better results might be achieved with an improved new algorithm. In contrast to this, we observed a better correlation of thermodilution COTranspulm and thermodilution COPAC measurements prior, during, and after CABG surgery.

Aged↗
PubMed2006

Increased interleukin-6 after cardiac surgery predicts infection.

Early diagnosis and treatment of infection after cardiac surgery with cardiopulmonary bypass (CPB) improves outcome. Conventional laboratory tests, such as C-reactive protein and white blood cell count can not distinguish patients with early infection from those with systemic inflammatory response syndrome but without infection. After CPB, there is a systemic release of proinflammatory and antiinflammatory cytokines, including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-10. We investigated the predictive ability of these variables for infection after cardiac surgery. Forty-six patients with impaired left ventricular ejection fraction (<60%), scheduled for cardiac surgery, were included. Plasma samples were drawn 1 day before and immediately before surgery, on admission to the intensive care unit, and on days 1, 3, and 7 after surgery. Infection was identified according to the criteria of the Centers for Disease Control and Prevention. After surgery 13 patients developed an infection. In patients with infection, confirmed a median of 4 days after surgery, all measurements of IL-6, and IL-10 on postoperative day 3 were significantly increased. Tumor necrosis factor-alpha, leukocytes, and C-reactive protein were not increased in these patients. Immediately after surgery blood glucose was significantly increased in patients with infection. Increased IL-6 after CPB is predictive of infection after cardiac surgery in patients with impaired left ventricular function.

Aged↗
PubMed2006

Clonidine attenuated early proinflammatory response in T-cell subsets after cardiac surgery.

T-cells play a central role in the immune response to injury. Cardiac surgery is associated with significant risk of systemic inflammatory response syndrome and subsequent unbalanced induction of proinflammatory cytokines. As clonidine has immunomodulating properties via reducing sympathetic activity, this study involved the analysis of T-cell function in the early postoperative period in patients undergoing coronary artery bypass graft surgery. Forty patients undergoing cardiac surgery were randomly allocated to one of the following groups: clonidine group (n = 20) [clonidine 1 microg kg(-1) h(-1)] and placebo group (n = 20). Study medication was started after induction of anesthesia and maintained until 6 h after surgery. Blood samples to determine Th1 and Th2 cells and cytotoxic lymphocytes (Tc1 and Tc2 cells) were drawn preoperatively, on admission to the intensive care unit, 6 and 12 h postoperatively as well as on the morning of days 1 and 2 after surgery. In the clonidine group significantly lower levels of Th1/Th2 ratios as well as Tc1/Tc2 ratios were found 6 h postoperatively compared to the placebo group (P < 0.05). Clonidine changed the ratio of T-lymphocyte subpopulations in peripheral blood in favor of a proinflammatory response, which might be favorable for maintaining immune balance after surgery.

Adrenergic alpha-Agonists↗
PubMed2006

Thawing procedures and the time course of clotting factor activity in fresh-frozen plasma: a controlled laboratory investigation.

BACKGROUND: In this study, we evaluated the effects of the thawing process of 2 commercially available devices on the activity of clotting factors, inhibitors and activation markers of the hemostatic system in fresh-frozen plasma (FFP). In an experimental procedure, FFP was thawed under running warm water at 42 degrees C. METHODS: Plasma of 20 healthy donors was sampled, separated, and distributed in 3 plasma bags. Within 2 h after sampling plasma bags was frozen at a temperature of -30 degrees C to -40 degrees C and stored for at least 8 wk. After sampling (baseline) as well as immediately and 1, 2, 4, and 6 h after thawing, the activity of FV, FVII, FVIII, fibrinogen, fibrin monomers (FM), d-dimers (DD), alpha2-antiplasmin (alpha2-AP), and protein S (PS) was determined from each plasma bag. RESULTS: From 1 h to 6 h after thawing, no significant differences in the activity of the investigated coagulation markers dependent on the thawing procedure were found. However, immediately after thawing and independent of the thawing procedure, the activity of FVII was significantly decreased (P < 0.01), whereas FM were significantly increased (P = 0.001). CONCLUSION: The thawing procedures studied exhibited no significant influence on activity and stability of the investigated markers of coagulation over the study period. The decreased activity of FVII and the clinical significance of the increase in FM require further research.

Adult↗
PubMed2005

Pulse contour analysis after normothermic cardiopulmonary bypass in cardiac surgery patients.

INTRODUCTION: Monitoring of the cardiac output by continuous arterial pulse contour (COPiCCOpulse) analysis is a clinically validated procedure proved to be an alternative to the pulmonary artery catheter thermodilution cardiac output (COPACtherm) in cardiac surgical patients. There is ongoing debate, however, of whether the COPiCCOpulse is accurate after profound hemodynamic changes. The aim of this study was therefore to compare the COPiCCOpulse after cardiopulmonary bypass (CPB) with a simultaneous measurement of the COPACtherm. METHODS: After ethical approval and written informed consent, data of 45 patients were analyzed during this prospective study. During coronary artery bypass graft surgery, the aortic transpulmonary thermodilution cardiac output (COPiCCOtherm) and the COPACtherm were determined in all patients. Prior to surgery, the COPiCCOpulse was calibrated by triple transpulmonary thermodilution measurement of the COPiCCOtherm. After termination of CPB, the COPiCCOpulse was documented. Both COPACtherm and COPiCCOtherm were also simultaneously determined and documented. RESULTS: Regression analysis between COPACtherm and COPiCCOtherm prior to CPB showed a correlation coefficient of 0.95 (P < 0.001), and after CPB showed a correlation coefficient of 0.82 (P < 0.001). Bland-Altman analysis showed a mean bias and limits of agreement of 0.0 l/minute and -1.4 to +1.4 l/minute prior to CPB and of 0.3 l/minute and -1.9 to +2.5 l/minute after CPB, respectively. Regression analysis of COPiCCOpulse versus COPiCCOtherm and of COPiCCOpulse versus COPACtherm after CPB showed a correlation coefficient of 0.67 (P < 0.001) and 0.63 (P < 0.001), respectively. Bland-Altman analysis showed a mean bias and limits of agreement of -1.1 l/minute and -1.9 to +4.1 l/minute versus -1.4 l/minute and -4.8 to +2.0 l/minute, respectively. CONCLUSION: We observed an excellent correlation of COPiCCOtherm and COPACtherm measurement prior to CPB. Pulse contour analysis did not yield reliable results with acceptable accuracy and limits of agreement under difficult conditions after weaning from CPB in cardiac surgical patients. The pulse contour analysis thus should be re-calibrated as soon as possible, to prevent false therapeutic consequences.

Cardiac Output↗
PubMed2005

An isotope exchange technique to assess mechanisms of sorption hysteresis applied to naphthalene in kerogenous organic matter.

The sorption of organic compounds to natural sorbents is often found to show hysteresis. The objective of this study was to develop an experimental technique based on the use of 14C isotopes to distinguish hysteresis due to experimental artifacts from true hysteresis due to thermodynamically irreversible processes. The study was also designed to investigate causation of true hysteresis (irreversible sorption). The technique determines the rates and the degree of isotope exchange (IE) on equilibrated sorption and desorption points at different constant bulk chemical concentrations. The technique was applied to the sorption of naphthalene (NAPH) on Beulah-Zap lignite, a low rank reference coal composed mainly of kerogen. Sorption of bulk was found to be reversible below 10(-5) g L(-1), but irreversible above 10(-4) g L(-1). Complete isotope exchange on sorption and desorption points that defined an irreversible cycle demonstrated that hysteresis was true. A comparison of normalized uptake and release kinetics of labeled and bulk NAPH at different concentrations revealed slow structural deformation processes of the sorbent during bulk sorption and desorption. This is taken as corroborating evidence for the pore deformation hypothesis of hysteresis in which incoming sorbate molecules induce quasi-reversible changes in the organic matter that lead to different pathways for sorption and desorption. Although unable to rule it out completely, the data demonstrate that physical entrapment of sorbate molecules plays a minor, if any, role to the observed hysteresis in this system.

Adsorption↗
PubMed2005

A thermodynamically based method to quantify true sorption hysteresis.

Sorption of organic chemicals to soils and sediments often shows true hysteresis (i.e., nonsingularity of the sorption-desorption isotherm not attributable to known experimental artifacts). Since true sorption hysteresis is fundamentally important to contaminant fate, a way to quantify it is desirable. Previously proposed indices of hysteresis are empirical and usually depend on the isotherm model. True sorption hysteresis to synthetic and natural organic solids has been attributed to irreversible alteration of the solid during the sorption-desorption cycle. Given this mechanism, we propose the Thermodynamic Index of Irreversibility (TII) for quantifying hysteresis in soils where natural organic matter dominates the sorption process. The TII is based on the difference in free energy between the real desorption state and the hypothetical fully reversible state. The index is 0 for completely reversible systems and approaches 1 as the process tends toward complete irreversibility. It does not require any assumptions about the physical properties or molecular composition of the solid, and it does not depend on a specific equilibrium model. A sensitivity analysis of measurement errors provides general recommendations for the setup of sorption-desorption experiments. The TII was applied to sorption of 1,4-dichlorobenzene (DCB) to two high-organic soils, Pahokee peat (PP) and Amherst soil (AS), and a low-rank coal reference material, Beulah-Zap lignite (BZL). Common artificial causes of hysteresis were eliminated. Hysteresis was significant in the peat and the coal. The TII was clearly concentration dependent for both solids; it decreased with concentration for the peat, but increased with concentration for the coal. The TII allows quantification of hysteresis as a function of sorbate-sorbent combination, concentration, time, and other variables.

Adsorption↗
PubMed2005

Characterization of charcoal adsorption sites for aromatic compounds: insights drawn from single-solute and bi-solute competitive experiments.

Charcoal, the residue of incomplete biomass burning that is found in many soils and sediments, is considered a high affinity sorbent for organic pollutants. However, little is known about the microscopic processes controlling sorption. The purpose of this study was to gain molecular-scale insight into the sorption on a charcoal of three weakly soluble aromatic compounds [benzene (BEN), toluene (TOL), and nitrobenzene (NBZ)] by conducting both single-solute and bi-solute experiments. The charcoal (420 m2 g(-1)) was produced from maple wood shavings by oxygen-limited pyrolysis at 673 K. Solute affinity for charcoal followed the order NBZ > TOL > BEN. Commonly employed sorption models did not adequately describe the single-solute isotherms. Competition in both TOL-BEN and the TOL-NBZ bi-solute systems was strong. Normalization of the isotherms for the hydrophobic driving force by using an existing free energy correlation between sorption and partitioning to an inert solvent (benzene or n-hexadecane) with a nonpolar aromatic compound calibration set resulted in a finding of enhanced sorption of NBZ relative to the coalesced BEN and TOL isotherms, indicating some specificity in the interaction of NBZ. The competitive data indicated 1:1 molar competition between BEN and TOL and between NBZ and TOL, showing conclusively that this specificity was not due to a subpopulation of sorption sites unique to NBZ. H-bonding was ruled out, as the relative affinity for the sorbent among the solutes did not change at all when increasing the solution pH from 6.5 to 11. 1H NMR experiments showed molecular complexation in chloroform between NBZ and model graphene polycyclic aromatic units (naphthalene, phenanthrene, and pyrene) which was absentfor BEN and TOL. This result, in combination with the results of a companion study (Zhu and Pignatello, Environ. Sci. Technol. (in press)), is used to support the existence of pi-pi electron donor-acceptor interactions between NBZ (electron acceptor) and the polycyclic aromatic charcoal surface (electron donor) as the cause of enhanced NBZ sorption.

Adsorption↗
PubMed2005

Increased interleukin-10 and cortisol in long-term alcoholics after cardiopulmonary bypass: a hint to the increased postoperative infection rate?

BACKGROUND: Previous studies have shown that 20% of all patients admitted to the hospital abuse alcohol and have increased morbidity after surgery. Long-term alcoholic patients are shown to suffer from immune alterations, which might be critical for adequate postoperative performance. Cardiac surgery with cardiopulmonary bypass (CPB) also leads to pronounced immune alteration, which might be linked with patients' ability to combat infections. Therefore, the aim of our study was to investigate the perioperative levels of TNF-alpha, interleukin-6, interleukin-10, and cortisol in long-term alcoholic and nonalcoholic patients undergoing cardiac surgery to elucidate a possible association with postoperative infections. METHODS: Forty-four patients undergoing elective cardiac surgery were included in this prospective study. Long-term alcoholic patients (n=10) were defined as having a daily ethanol consumption of at least 60 g and fulfilling the Diagnostic and Statistical Manual of Mental Disorders for alcohol abuse. The nonalcoholic patients (n=34) were defined as drinking less than 20 g ethanol per day. Blood samples were obtained to analyze the immune status upon admission to hospital, the morning before surgery and on admission to the ICU, the morning of days one and three after surgery. RESULTS: Basic characteristics of patients did not differ between groups. Long-term alcoholics had a fourfold increase in postsurgery infection rate and prolonged need for ICU treatment and mechanical ventilation. Postoperative levels of interleukin-10 and cortisol were significantly increased in long-term alcoholic patients compared with nonalcoholic patients. These observations were in line with postoperative interleukin-10 being predictive for postoperative infectious complications. CONCLUSIONS: The increased infection rate in long-term alcoholics strengthens the urgent need for interventional approaches providing modulation of the perioperative immune and HPA response in these high-risk patients to counteract their postoperative immune suppression.

Aged↗
PubMed2005

Recombinant activated factor VII for refractory bleeding after cardiac surgery--a retrospective analysis of safety and efficacy.

OBJECTIVE: Analysis of safety and efficacy of recombinant activated factor VII (rFVIIa) used as the last resort for refractory bleeding after cardiac surgery. DESIGN: Retrospective cohort analysis and matched pairs analysis with historic controls were performed. In the rFVIIa group, which also received conventional hemostatic therapy, data were collected for a median of 14 hrs from admission to the intensive care unit (ICU) to the administration of rFVIIa and for the following 24 hrs. In the control group, which received only conventional hemostatic therapy, data were collected for 14 and then for 24 hrs after admission to the ICU. SETTING: University hospital. PATIENTS: Twenty-four patients matched with historic controls. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: No thromboembolic complications were observed in the rFVIIa group. Blood loss and transfusion requirements were significantly reduced in the period after the administration of rFVIIa. However, in the 24-hr period after rFVIIa administration, blood loss (p = .140) and transfusion of packed red blood cells (p = .442) and fresh frozen plasma (p = .063) were not different between the rFVIIa and control groups. Platelet concentrates (p = .004) were transfused less in the control group. Mortality and 6-month survival rates were not different between the groups. CONCLUSIONS: When used as a last resort, rFVIIa was safe but not incrementally efficacious over conventional hemostatic therapy.

Aged↗
PubMed2004

Bispectral index versus COMFORT score to determine the level of sedation in paediatric intensive care unit patients: a prospective study.

INTRODUCTION: Most clinicians give sedatives and analgesics according to their professional experience and the patient's estimated need for sedation. However, this approach is prone to error. Inadequate monitoring of sedation and analgesia may contribute to adverse outcomes and complications. With this in mind, data obtained continuously using nonstimulating methods such as bispectral index (BIS) may have benefits in comparison with clinical monitoring of sedation. The aim of this prospective observational trial was to evaluate the use of electroencephalographic (EEG) BIS for monitoring sedation in paediatric intensive care unit (PICU) patients. METHODS: Forty paediatric patients (<18 years) were sedated for mechanical ventilation in a cardiac surgical and general PICU. In each paediatric patient BIS and COMFORT score were obtained. The study protocol did not influence ongoing PICU therapy. BIS and corresponding COMFORT score were collected three times for each patient. Measurements with the best starting EEG impedances were analyzed further. Deep sedation was defined as a COMFORT score between 8 and 16, and light sedation as a score between 17 and 26. Biometric and physiological data, and Pediatric Risk of Mortality III scores were also recorded. RESULTS: There was a good correlation (Spearman's rho 0.651; P = 0.001) between BIS and COMFORT score in the presence of deep sedation and low starting impedance. Receiver operating characteristic (ROC) analysis revealed best discrimination between deep and light sedation at a BIS level of 83. CONCLUSION: In the presence of deep sedation, BIS correlated satisfactorily with COMFORT score results if low EEG impedances were guaranteed.

Adolescent↗