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Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 73 records · Page 4Linked to original sources
PubMed2001

Hydroxyethyl starch (HES) does not directly affect renal function in patients with no prior renal impairment.

STUDY OBJECTIVES: To examine the effects of hydroxyethyl starch (HES) on renal function. DESIGN: Randomized, controlled trial. SETTING: Operating theatre of a university hospital. PATIENTS: 60 ASA physical status I and II male patients undergoing middle ear surgery. INTERVENTIONS: Patients received either lactated Ringer's solution (LRS) or one of three HES solutions. The HES solutions were administered in a dose of 15 mL/kg bodyweight (bw), the Ringer's solution in a dose of 60 mL/kg bw, after induction of anesthesia over a period of one hour. MEASUREMENTS: Blood and urine samples for hormone and enzyme tests were obtained at defined times before, during, and after surgery. Urine excretion, glomerular filtration rate (GFR), renal plasma flow, and routine hemodynamic parameters were measured simultaneously. MAIN RESULTS: There were no significant intergroup differences regarding GFR, renal plasma flow, or tubular and glomerular integrity as measured by specific proteins and enzymes (alpha-1-microglobulin, Tamm-Horsfall-protein, immunoglobulin G, and N-acetyl-beta-D-glucosaminidase). Arginine vasopressin decreased in all groups during and following anesthesia, aldosterone and plasma renin activity decreased only in the HES groups, and angiotensin II decreased only in the HES 200/0.5 group. Central venous pressure increased during fluid administration in the LRS group and returned to baseline sooner in the HES groups. CONCLUSIONS: Hydroxyethyl starch administration appears to be risk-free with regard to renal function in patients without preexisting renal dysfunction who undergo general anesthesia. The relevance of the decrease in aldosterone following HES therapy needs further investigation.

Adult↗
PubMed2001

Effects of diazepam on neutrophil (PMN) free amino acid profiles and immune functions in vitro. Metabolical and immunological consequences of L-alanyl-L-glutamine supplementation.

The objective of this study was to determine the effects of diazepam, L-alanyl-L-glutamine (ala-gln) or diazepam combined with ala-gln on polymorphonuclear leukocyte (PMN) free amino acid profiles. In a parallel study the effects on PMN immune functions were also documented for the first time. The incubation of whole blood with diazepam led to significant changes in PMN free glutamine, aspartate, glutamate, ornithine, arginine, citrulline, taurine and methionine as well as branched chain and neutral amino acid concentrations. Ala-gln caused significant increases in PMN glutamine and alanine and asparagine, aspartate, glutamate, ornithine, arginine, serine and glycine profiles. Regarding PMN immune functions, diazepam significantly decreased superoxide anion (O(2)(-)) and hydrogen peroxide production (H(2)O(2)) and myeloperoxidase activity (MPO) while ala-gln significantly increased PMN immune functions. Ala-gln supplemented to diazepam largely reversed the changes in PMN amino acid profiles and PMN immune functions brought about by diazepam. Overall, diazepam or ala-gln lead to significant changes in PMN free amino acids. Important PMN immune functions also seem to be affected. In regards to the results, there is significant relevance to the pharmacological regimens which enhance the supply of diazepam or ala-gln in whole blood suggesting that considerable changes in PMN "labile free amino acid pool" occur. These regimens often follow beneficial nutritional therapy or maleficent pharmacological stress and may be one of the determinants in cell nutrition which influence PMN function. It is partially through its effect on PMN labile free amino acid pool that ala-gln supplemented to diazepam may maintain PMN immune functions in vitro.

Journal Article↗
PubMed2001

Evaluation of the suitability of a patient data management system for ICUs on a general ward.

The development of the ICUData patient data management system (PDMS) for intensive care units (ICU), by IMESO GmbH, Hüttenberg, Germany, was based on the assumption that processes and therapies at ICU are the most complex with the highest data density compared with those in other wards. Based on experience with the system and on a survey conducted among users at our pain clinic, we evaluated whether the concept of the present software architecture, which sufficiently reproduces processes and data at an ICU, is suitable as a PDMS for general wards. The highly modular and client-centric approach of the PDMS is founded on a message-based communications architecture (HL7). In the beginning of the year 2000, the system was implemented at the pain management clinic (12 beds) of our hospital. To assess its user friendliness, we conducted a survey of medical staff (n=14). From April 1st 2000 to August 31st 2000, all clinical and administrative data of 658 patients at the pain management clinic were recorded with the PDMS. From the start, all users had access to data and information of other connected data management systems of the hospital (e.g. patient administrative data, patient clinical data). Staff members found the system mostly useful, clearly presented, practical, and easy to learn and use. Users were relatively satisfied with stability and performance of the program but mentioned having only limited knowledge of the program's features. The need for external support during a computer crash was rated negatively. Despite the need for further usage training and improved program performance, the software architecture described seems to be a promising starting point for the construction of a PDMS for general wards.

Attitude of Health Personnel↗
PubMed2001

Influence of colloid fluids on polymorphonuclear granulocyte function in vivo.

BACKGROUND: Granulocytes have a role in the immediate immune response. In a previous investigation we could demonstrate in vitro a moderate increase of the complement receptors CR1 (CD35) and CR3 (CD11b/CD18) on the surface of polymorphonuclear neutrophils (PMN) after incubation of whole blood with colloids. To elucidate the clinical significance, we investigated if these changes were also present in vivo. METHODS: The study was performed prior to anaesthesia for orthopaedic surgery. A total of 60 ASA-I patients was evaluated. Patients received in a randomised manner 7 mL/kg of the following solutions: human albumin 5% (HA), gelatine 4% (GEL), hydroxyethylstarch solution 6% with MW 200,000 Da, degree of substitution 0.5 (HES), or Ringer's solution. Prior to the infusion, at the end (30 min) and again 30 min later, blood samples were taken. Blood was incubated with fluorescein-conjugated monoclonal antibodies (CD11b, CD16, CD35, CD62L) and analysed with flow cytometry. RESULTS: HA, GEL, HES, and Ringer's solution failed to induce significant differences in the expression of complement receptors CR1 (CD35) and CR3 (CD11b/CD18), Fc gamma receptor IIIb (CD16), and of L-selectin (CD62L) receptor on the surface of PMN. CONCLUSIONS: Application of colloids like HA, GEL, or HES in moderate amounts shows no short-term effect on adhesion or activation molecules on granulocytes. However, in high doses, infused in situations such as multiple trauma and sepsis, the consequences on the function of PMN may be speculative and require further investigations.

Adult↗
PubMed2001

Inhibitory effects of S-(-) and R-(+) bupivacaine on neutrophil function.

BACKGROUND: Local anesthetics inhibit migration, enzyme release and superoxide anion generation of polymorphonuclear leukocytes (PMN). Due to their ability to phagocytose and kill bacteria PMN represent a major defense mechanism in the circulating blood. In this study we determined the influence of racemic bupivacaine and its enantiomers on neutrophil phagocytic activity, oxidative burst as well as surface expression of complement and Fcgamma receptors. METHODS: Venous blood was pre-incubated with different concentrations of either racemic bupivacaine, R-(+) or S-(-) bupivacaine. Fluoresceine isothiocyanate (FITC)-labeled antibodies against Fcgamma receptor III (CD16), complement receptor 1 (CD35) and complement receptor 3 (CD11b) were used to determine surface receptor expression. Phagocytic activity was measured by ingestion of FITC-labeled vital Staphylococcus aureus. Oxidative burst was determined by conversion of nonfluorescent dihydrorhodamine 123 into fluorescent rhodamine 123. Fluorescent intensity of each sample was determined by flow cytometry. RESULTS: Racemic bupivacaine inhibited surface receptor expression, phagocytosis, and oxidative burst in a time- and concentration-dependent manner. Although the S-(-) enantiomer exerted significantly less inhibitory action on neutrophil function compared to R-(+) and racemic bupivacaine, these effects were small compared to the overall changes. CONCLUSION: These findings suggest that bupivacaine impairs surface receptor expression and may thereby contribute to reduced phagocytic activity and oxidative burst. Enantiomer-specific effects of bupivacaine may play a minor role in the inhibition of these leukocyte functions.

Adult↗
PubMed2001

Controlled hypercapnia during one-lung ventilation in patients undergoing pulmonary resection.

BACKGROUND: In a pilot study, the haemodynamic and gas exchange effects of acute hypercapoia during one-lung ventilation in thoracotomy patients were investigated. The effects of normocapnic one-lung ventilation (OLV-N) on haemodynamics and pulmonary gas exchange were compared with those of hypercapnic one-lung ventilation (OLV-H) in 14 patients undergoing pulmonary lobectomy. METHODS: Hypercapnia was induced by decreasing tidal volume until PaCO2 increased to 8-9 kPa. During OLV, minute ventilation was reduced from 8.8+/-1.7 to 4.2+/-0.7 l min(-1). RESULTS: Cardiac index (from 3.3+/-0.6 to 3.9+/-0.6 l min(-1), P<0.01) and pulmonary vascular resistance index (from 245+/-96 to 347+/-125 dyn s cm(-5) m(-2), P<0.05) increased during OLV-H, whereas systemic vascular resistance index decreased from 1952+/-403 to 1636+/-361 dyn s cm(-5) m(-2) (P<0.01). Pulmonary oxygenation remained unchanged. CONCLUSIONS: All patients had an uneventful course during OLV-H. The determinants of pulmonary oxygenation during hypercapnic one-lung ventilation remain to be further elucidated.

Blood Gas Analysis↗
PubMed2001

The influence of intravenous anaesthetics on the activity of enzymes released from polymorphonuclear leucocytes in vitro.

BACKGROUND AND OBJECTIVE: Polymorphonuclear leucocytes make a decisive contribution to defence against bacterial infections. In particular, the effects of anaesthetics on non-oxidative bactericidal mechanisms have previously only been superficially examined. Although the influence of anaesthetic agents on oxidative bactericidal activity has been thoroughly examined, our study concentrated on the effect on non-oxidative processes, which appears to have been a neglected field of research. METHODS: The effects of methohexital, etomidate, ketamine, fentanyl and morphine on the activity of lysozyme and beta-glucuronidase released from polymorphonuclear leucocytes have been studied in vitro. The activity of lysozyme was determined by recording the changes in the turbidity of a suspension of micrococcus lysodeicticus caused by the enzymatic action of lysozyme. beta-glucuronidase activity was photometrically measured by the enzymatic cleavage of phenolphthalein glucuronic acid. RESULTS: High concentrations of methohexital inhibited lysozyme activity; however, etomidate and morphine caused an increase of beta-glucuronidase activity in therapeutic plasma concentrations. While there was no effect of etomidate on lysozyme activity, all concentrations tested significantly stimulated beta-glucuronidase activity. This result was unexpected because intravenous anaesthetics have previously shown a tendency to suppress polymorphonuclear leucocyte functions. Whereas the inhibition of lysozyme activity by the high concentration of methohexital was no surprise, the increase of beta-glucuronidase activity caused by etomidate, ketamine, fentanyl and morphine was quite unexpected. CONCLUSIONS: At present, the underlying mechanism for the increase of beta-glucuronidase activity caused by etomidate, ketamine, fentanyl and morphine is unknown. The fact that there was no influence of these agents on lysozyme activity possibly suggests that the anaesthetic agents have different effects on azurophilic and specific granules. Since in vitro investigations have their limitations, it is too early to draw practical consequences from our study. Moreover, at present it is unclear whether an increase of beta-glucuronidase activity in vivo is an advantage or not. In any case, we think it advisable to perform further investigations on the influence of anaesthetic agents on oxygen-independent bactericidal mechanisms.

Anesthetics, Intravenous↗
PubMed2001

Factors determining length of stay of surgical day-case patients.

BACKGROUND AND OBJECTIVE: Factors which lead to prolonged stay in the day-care unit and unplanned admission after day-case surgery are poorly understood. METHODS: Data sets of 3152 day-case patients were collected with a computerized online record keeping system (NarkoData). Predictors of prolonged postoperative stay including unanticipated admission were identified using univariate analysis. Charts of patients, who needed admission, were reviewed. RESULTS: 13.2% of day-case patients had a postoperative stay < or = 3 h, 55.3% 3-6 h and 26.2% > or = 6 h. The rate of unanticipated admission was 5.4%. Intraoperative haemoglobin concentration and blood loss were the best predictors of a prolonged postoperative stay. Other significant predictors were female gender, advanced age, longer duration of surgery, larger volume of infusions, intubation, spinal anaesthesia, intraoperative use of opioids and non-depolarizing muscle relaxants, high pain score, nausea and vomiting and prolonged preoperative waiting time. Chart review of patients admitted to hospital confirmed the validity of the statistically significant predictors. CONCLUSIONS: In day-case surgery, the predictors of prolonged stay in the day-care unit and unplanned Hospital admission are mainly related to the surgical procedure.

Ambulatory Surgical Procedures↗
PubMed2001

Methohexital affects neutrophil (PMN) dynamic free amino acid pool and immune functions in vitro.

BACKGROUND AND OBJECTIVE: The objective of this study was to determine the dose as well as the duration of exposure-dependent effects of methohexital on neutrophil [polymorphonuclear leucocyte (PMN)] free amino acid profiles and, in a parallel study, on PMN immune functions. METHODS: Whole blood samples were taken from 20 volunteers and incubated with methohexital [0 (control), 3.6, 26, 130 and 260 microg mL-1] for 10, 30, 60 or 120 min. PMN amino acid profiles were documented using advanced PMN separation and high-performance liquid chromatography procedures. Superoxide anion (O2-) and hydrogen peroxide production (H2O2), and activity of released myeloperoxidase (MPO), were determined photometrically. RESULTS: After methohexital, significant dose (> or = 26 microg mL-1) as well as duration of exposure-dependent (> or = 30 min) increases in histidine, isoleucine, leucine, valine, methionine, serine, glycine, threonine, and decreases in glutamine, glutamate, aspartate, asparagine, arginine, ornithine, citrulline, alanine and taurine were observed (P < or = 0.05). Concerning PMN immune functions, methohexital significantly decreased O2-, H2O2 formation and MPO (> or = 26 microg mL-1, > or = 30 min, P < or = 0.05). CONCLUSIONS: Altogether, there is significant relevance to the pharmacological regimens which enhance the supply of methohexital in whole blood. In regards to our results, we suggest that considerable changes in PMN 'dynamic free amino acid pool', for example induced by methohexital, may be one of the determinants in cell nutrition adversely affecting PMN metabolism. It is partially through its effect on the PMN free amino acid pool that maleficent pharmacological stress may have an unintentional influence on PMN immune functions.

Adult↗
PubMed2001

Ethanol reduces excitability in a subgroup of primary sensory neurons by activation of BK(Ca) channels.

Ethanol effects on the central nervous system have been well investigated and described in recent years; modulations, by ethanol, of several ligand-gated and voltage-gated ion channels have been found. In this paper, we describe a shortening of action potential duration (APD) by ethanol in approximately equal to 40% of small diameter neurons in rat dorsal root ganglia (DRG). In these neurons, designated as group A neurons, we observed an ethanol-induced increase in whole-cell outward-current. As iberiotoxin, a specific blocker of large-conductance calcium-activated K+ channels (BK(Ca) channels), blocks the effects of ethanol, we investigated the interaction between these channels and ethanol in outside-out patches. Open probability of BK(Ca) channels was increased 2-6 x depending on the concentration (40-80 mM approximately equal to 2-4 per thousand v/v) of ethanol. Functional consequences were a prolongation of the refractory period, which was reversible after addition of iberiotoxin, and reduced firing frequency during ethanol application. In contrast, another type of neuron (group B) showed a prolonged APD during application of ethanol which was irreversible in most cases. In 90% of cases, neurons of group A showed a positive staining for isolectin B4 (I-B4), a marker for nociceptive neurons. We suggest that the activation of BK(Ca) channels induced by clinically relevant concentrations of ethanol, the resulting modulations of APD and refractory period of DRG neurons, might contribute to clinically well-known ethanol-induced analgesia and paresthesia.

Action Potentials↗
PubMed2001

[Transmissible spongiform encephalopathies--anesthesiologic and intensive care management].

The transmissible spongiform encephalopathies (TSE) are known to affect humans and various animals. The bovine spongiform encephalopathy (BSE) and the human Creutzfeldt-Jacob disease (CJD) are among the most notable degenerative disorders caused by prions. Considering the BSE epidemic and the description of a new variant of Creutzfeldt-Jacob disease (nvCJD), which is probably related to bovine spongiform encephalopathy, TSE have recently gained a lot of public attention. Although the causative factors (prions, viruses) are still under discussion, none of the present concepts are explanatory for all aspects of the human CJD. CJD may present as a sporadic, genetic, or infectious illness and there is now considerable concern that bovine prions may have been passed to humans. To exclude transmission of CJD via medical products and instruments, the effectiveness of cleaning, disinfection and sterilization procedures must be firmly established. This manuscript presents an overview to anaesthesiology and intensive care medicine of recommended inactivation procedures and assessed these procedures in the light of the inactivation of prions.

Anesthesia↗
PubMed2001

Impairment of renal function after cardiopulmonary bypass is not influenced by dopexamine.

INTRODUCTION: The objective of this study was to evaluate the effects of dopexamine on renal function in 4 groups of patients either with or without renal dysfunction. Transient renal dysfunction is often not clinically relevant in patients with normal renal function, but it is an important clinical factor in patients with pre-existing renal failure. Dopexamine (DX) is a commonly used catecholamine which probably exerts a selective effect at the splanchnic bed. MATERIAL AND METHODS: 24 patients with normal renal function and 24 patients with impaired renal function (creatinine in serum > or = 1.5 mg/dL) were each randomly allocated to 2 groups. Group 1 (control) without renal dysfunction and group 3 (control/dysfunction) with renal dysfunction were considered as control groups, while the patients in DX and DX/dysfunction groups received 1 microg/kg/min dopexamine until the end of surgery. Kidney function was investigated using standard parameters and by investigating specific proteins and enzymes. RESULTS: All patients showed pathologic excretions of the investigated parameters during cardiopulmonary bypass (CPB) with no differences between the study groups. The distal tubule, the lysosomal regions, Henle's loop and the glomerular tuft were all damaged. Heart rate and cardiac index increased significantly in the DX-groups, first until the end of surgery, second until the start of ECC. CONCLUSION: Dopexamine at a dose of 1 microg/kg/min had no influence on renal function and protein excretion and cannot be regarded as a kidney function protecting substance.

Adrenergic beta-Agonists↗
PubMed2001

Combination of external chest wall oscillation with continuous positive airway pressure.

We studied the effects of continuous positive airway pressure (CPAP) on pulmonary gas exchange during external chest wall oscillation (ECWO), and the relationship with obesity, in nine patients with normal body weight (group 'N') and 10 obese patients (group 'O'). During ECWO with CPAP 5, PaCO2 decreased in group 'O' (6.0 (SD 0.8) to 5.6 (0.5) kPa, P<0.05), whereas it increased in group 'N' at all levels (P<0.01). Arterial PO(2) (P<0.001) was greater and PaCO2 (P<0.01) less in group 'N' during CPPV and ECWO plus CPAP. We also compared the haemodynamic effects of ECWO plus CPAP with those of continuous positive pressure ventilation (CPPV). ECWO plus CPAP and CPPV were applied for 30 min to 6 ASA III patients. Cardiac output (CI 2.7 (0.5) vs 2.1 (0.2) litre x min(-1) x m(-2), P<0.05) and stroke volume (SVI 49 (9) vs 32 (6) ml x m(-2), P<0.05) were greater during ECWO plus CPAP than with CPPV. ECWO is less effective in obese individuals than in those with normal body weight, and the effect of CPAP in overweight individuals is small.

Adult↗
PubMed2001

Regional hemostatic status and blood requirements after total knee arthroplasty with and without tranexamic acid or aprotinin.

UNLABELLED: Antifibrinolytics seem to reduce postoperative blood loss after total knee arthroplasty. Few studies have shown the impact of these drugs on the mechanisms of coagulation. The purpose of this study was to examine coagulation/fibrinolysis variables as well as blood loss after total knee arthroplasty with and without antifibrinolytics in the operated limb on a regional level. Thirty-six patients were randomized into one of three groups to receive aprotinin, tranexamic acid, or no medication. We took blood samples of the femoral vein before deflating the tourniquet and after 5, 10, 30, 60, 120 min and on the first postoperative day. The implantation of a knee prosthesis in artificial ischemia caused a significant activation of coagulation and fibrinolysis in the regional circulation. Tranexamic acid and aprotinin did not cause a significant modulation of fibrinolysis variables or a significant reduction of postoperative bleeding and transfusion requirements. One of the differences in comparison to other studies was the decreased total blood loss. The use of bone cement as well as surgical hemostasis before wound closure may be regarded as reasons for this. Therefore, primarily these methods should be used because there is no increased risk of adverse drug effects. IMPLICATIONS: After total knee arthroplasty total blood loss may be kept in a low range if methods such as cemented knee prosthesis and surgical hemostasis are used. In this case aprotinin and tranexamic acid did not cause a significant modulation of fibrinolysis variables or a significant reduction of postoperative bleeding.

Adult↗
PubMed2001

Effect of drugs used for neuropathic pain management on tetrodotoxin-resistant Na(+) currents in rat sensory neurons.

BACKGROUND: Tetrodotoxin-resistant Na(+) channels play an important role in generation and conduction of nociceptive discharges in peripheral endings of small-diameter axons of the peripheral nervous system. Pathophysiologically, these channels may produce ectopic discharges in damaged nociceptive fibers, leading to neuropathic pain syndromes. Systemically applied Na(+) channel--blocking drugs can alleviate pain, the mechanism of which is rather unresolved. The authors investigated the effects of some commonly used drugs, i.e., lidocaine, mexiletine, carbamazepine, amitriptyline, memantine, and gabapentin, on tetrodotoxin-resistant Na+ channels in rat dorsal root ganglia. METHODS: Tetrodotoxin-resistant Na(+) currents were recorded in the whole-cell configuration of the patch-clamp method in enzymatically dissociated dorsal root ganglion neurons of adult rats. Half-maximal blocking concentrations were derived from concentration-inhibition curves at different holding potentials (-90, -70, and -60 mV). RESULTS: Lidocaine, mexiletine, and amitriptyline reversibly blocked tetrodotoxin-resistant Na(+) currents in a concentration- and use-dependent manner. Block by carbamazepine and memantine was not use-dependent at 2 Hz. Gabapentin had no effect at concentrations of up to 3 mm. Depolarizing the membrane potential from -90 mV to -60 mV reduced the available Na(+) current only by 23% but increased the sensitivity of the channels to the use-dependent blockers approximately fivefold. The availability curve of the current was shifted by 5.3 mV to the left in 300 microm lidocaine. CONCLUSIONS: Less negative membrane potential and repetitive firing have little effect on tetrodotoxin-resistant Na(+) current amplitude but increase their sensitivity to lidocaine, mexiletine, and amitriptyline so that concentrations after intravenous administration of these drugs can impair channel function. This may explain alleviation from pain by reducing firing frequency in ectopic sites without depressing central nervous or cardiac excitability.

Amitriptyline↗
PubMed2001

Suppression of potassium conductance by droperidol has influence on excitability of spinal sensory neurons.

BACKGROUND: During spinal and epidural anesthesia with opioids, droperidol is added to prevent nausea and vomiting. The mechanisms of its action on spinal sensory neurons are not well understood. It was previously shown that droperidol selectively blocks a fast component of the Na+ current. The authors studied the action of droperidol on voltage-gated K+ channels and its effect on membrane excitability in spinal dorsal horn neurons of the rat. METHODS: Using a combination of the patch-clamp technique and the "entire soma isolation" method, the action of droperidol on fast-inactivating A-type and delayed-rectifier K+ channels was investigated. Current-clamp recordings from intact sensory neurons in spinal cord slices were performed to study the functional meaning of K+ channel block for neuronal excitability. RESULTS: Droperidol blocked delayed-rectifier K+ currents in isolated somata of dorsal horn neurons with a half-maximum inhibiting concentration of 20.6 microm. The A-type K+ current was insensitive to up to 100 microm droperidol. At droperidol concentrations insufficient for suppression of an action potential, the block of delayed-rectifier K+ channels led to an increase in action potential duration and, as a consequence, to lowering of the discharge frequency in the neuron. CONCLUSIONS: Droperidol blocks delayed-rectifier K+ channels in a concentration range close to that for suppression of Na+ channels. The block of delayed-rectifier K+ channels by droperidol enhances the suppression of activity in spinal sensory neurons at drug concentrations insufficient for complete conduction block.

Animals↗