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Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 253 records · Page 14Linked to original sources
PubMed1995

The effect of the anticoagulation regimen on endothelial-related coagulation in cardiac surgery patients.

Heparin is still the most commonly used anticoagulant in cardiac surgery necessitating cardiopulmonary bypass. In recent years, endothelial-related coagulation (e.g. thrombomodulin/protein C-system) has enlarged our knowledge of the regulation of haemostasis. In a controlled randomised study, the influence of different regimens of anticoagulation on the thrombomodulin/protein C-system was studied. Sixty patients undergoing elective coronary artery bypass grafting were randomly allocated into four groups (n = 15) to receive: 300 IU.kg-1 of heparin before bypass; 600 IU.kg-1 of heparin; 300 IU.kg-1 of heparin as bolus followed by a continuous infusion of 10 000 IU.h-1 until the end of bypass; or 600 IU.kg-1 of heparin plus 'high dose' aprotinin (2 million IU of aprotinin before bypass, 500 000 IU.h-1 until the end of the operation and 2 million IU added to the bypass pump prime). Grouping was blinded for the surgeon and the anaesthetist. Plasma concentrations of thrombomodulin, protein C and (free) protein S as well as thrombin/antithrombin III were measured by enzyme-linked-immunosorbent assays after induction of anaesthesia, during and after bypass, at the end of surgery, 5 h after bypass, and on the first postoperative day. Activated clotting time was significantly longer during bypass in group 2 (566 (60)s) and group 4 (655 (59)s), whereas standard coagulation parameters showed no differences between the four groups. Blood loss and use of homologous blood and blood products were highest in groups 2 and 3. Thrombomodulin plasma levels were similar (and normal) at baseline (< 40 ng.l-1), decreased during bypass and reached baseline values postoperatively without showing significant group differences. Protein C did not show any differences among the groups within the investigation period. 'Free' protein S plasma levels were most reduced in group 1 (from 68 (8)% to 48 (9)% after bypass). Thrombin/antithrombin III plasma concentrations increased most in groups 1 (to 69 (14) micrograms.l-1 after bypass) and 2 (to 48 (7) micrograms.l-1 after bypass), whereas they remained significantly lower in groups 3 and 4. The thrombomodulin/protein C-system was not significantly influenced by the regimen of anticoagulation. Administration of 'high-dose' heparin was associated with the highest blood loss, which could not be related to endothelial-associated coagulation.

Aged↗
PubMed1995

Cardiorespiratory effects of continuous i.v. administration of the ACE inhibitor enalaprilat in the critically ill.

1. Cardiorespiratory effects of long-term, continuous i.v. administration of the ACE inhibitor enalaprilat were studied. 2. Forty-five consecutive critically patients suffering from trauma or postoperative complications were randomly separated into three groups (15 patients in each group) receiving either 0.25 mg h-1 or 0.50 mg h-1 enalaprilat, respectively, or saline solution as placebo (= control group). The infusion was continued for 5 days. 3. Haemodynamic and respiratory parameters were intensively monitored on admission to the intensive care unit (= 'baseline' values) and daily during the next 5 days. 4. Mean arterial blood pressure (MAP) decreased significantly only in the enalaprilat-treated patients, whereas heart rate (HR) remained unchanged in these patients. 5. Pulmonary capillary wedge pressure (PCWP) and pulmonary artery pressure (PAP) were decreased by enalaprilat (0.50 mg h-1: PAP (mean +/- s.d.) decreased from 28.0 +/- 4.1 to 24.0 +/- 3.0 mm Hg) and remained significantly lower than in the control group. In the untreated control group, cardiac index (CI), oxygen consumption (VO2I) and oxygen delivery (DO2I) significantly decreased, which was blunted by enalaprilat infusion. Oxygen extraction (O2-extr) increased in both enalaprilat groups (0.25 mg h-1: from 26.1 +/- 5.5 to 30.4 +/- 4.0%; 0.50 mg h-1: 25.2 +/- 5.6 to 30.9 +/- 4.4%) and decreased in the control patients. 6. Right ventricular haemodynamics improved by enalaprilat infusion (0.50 mg h-1: RVEF increased from 40.0 +/- 3.5 to 45.5 +/- 4.0%). Lactate plasma concentrations decreased in the group with 0.50 mg h-1 enalaprilat (from 1.9 +/- 1.0 to 1.3 +/- 0.3 mg dl-1) and increased in the control patients. 7. Continuous infusion of the ACE inhibitor enalaprilat exerted beneficial cardiorespiratory effects in the critically ill. The widespread common risk of altered perfusion with decreased CI, DO2, VO2, O2-extr and increased lactate concentration was blunted by enalaprilat infusion. 8. Although 0.5 mg h-1 enalaprilat was most effective, a dose of 0.25 mg h-1 also showed beneficial haemodynamic effects in the critically ill.

Adult↗
PubMed1995

The effects of midazolam, droperidol, fentanyl, and alfentanil on phagocytosis and killing of bacteria by polymorphonuclear leukocytes in vitro.

Polymorphonuclear leukocytes (PMNL) make an outstanding contribution to the defence against invading bacteria. We studied the effects of midazolam, droperidol, fentanyl, and alfentanil on phagocytosis and killing of Staphylococcus aureus and Escherichia coli by PMNL in vitro. Using a method described by Eggleton et al., PMNL were isolated from venous blood samples obtained from ten volunteers. The fluorescence microscopic method mentioned by Bellinati-Pires et al. was used to examine phagocytosis and killing. Whereas both midazolam and droperidol caused a significant inhibition of phagocytosis as well as bactericidal activity, fentanyl and alfentanil did not influence these PMNL functions. In order to find out whether midazolam and droperidol are able to intensify perioperative bacterial infections in vivo as well, additional clinical studies should be conducted.

Adult↗
PubMed1995

Increase of interleukin-6 plasma concentrations and HLA-DR positive T-lymphocytes after hypotensive anaesthesia with sodium nitroprusside.

Interleukin-6 (IL-6), a cytokine involved in the pathogenesis of sepsis and septic shock, and lymphocyte subpopulations were measured in blood circulation of patients receiving sodium nitroprusside (SNP) for induction of hypotension. The aim of this study was to evaluate whether this procedure influences distribution of lymphocyte subsets and IL-6 response. 30 patients of ASA physical status I and II scheduled for nose-septum correction were randomly assigned to the SNP- or control group (without SNP). Patients were anaesthetized with fentanyl, etomidate and isoflurane in 66% nitrous oxide. SNP was administered continuously during 60 min and mean arterial blood pressure was reduced to 50 mmHg. Before and after induction of anaesthesia, 60 min after the beginning of the operation (end of SNP-infusion) and on the first postoperative day, IL-6 plasma concentrations were determined by ELISA. The percentages of B-, T-lymphocytes, T-helper, T-suppressor cells and HLA-DR positive (activated) T-lymphocytes were examined by direct immunofluorescence using monoclonal antibodies. On the first day after surgery IL-6 plasma concentrations were significantly elevated in the SNP-group compared to preoperative values. In this group the values were higher than in control patients [30.5 (10.9-47.5) pg/ml vs. 17.4 (8.5-21.5) pg/ml]. The percentage of HLA-DR positive T-cells was 25.8 +/- 4.9% in the patients with SNP on the first postoperative day; it was significantly higher than in control patients [16.5 +/- 3.7%]. We conclude that SNP-administration increases percentage of activated T-cells and IL-6 secretion.

Adolescent↗
PubMed1995

Influence of different flow modi during extracorporeal circulation on endothelial-derived vasoactive substances.

Influences of shear stress on endothelin (ET) as well as prostacyclin (PGF) levels are common findings in different experimental settings. Thus, plasma levels of both substances seem to be a good tool to verify if different flow modi can be produced in blood vessels by generating pulsatile flow with a roller pump. In the present study, 20 patients scheduled for elective aortocoronary bypass operation were divided into two groups at random. One group was perfused with nonpulsatile (CON-group) and the other with pulsatile flow (PULS-group) during extracorporeal circulation. ET and PGF plasma levels were monitored perioperatively together with parameters of renal function and haemodynamic data. ET values were only slightly elevated at the end of extracorporeal circulation (mean baseline value; CON 3.1 pg/ml and PULS 3.2 pg/ml; mean maximal values at the end of cardiopulmonary bypass (CPB) 4.0 pg/ml and 3.9 pg/ml respectively). Prostacylin values (median baseline values: CON 56.7 pg/ml and PULS 57.1 pg/ml) peaked at the end of operation (median CON 117.8 pg/ml and PULS 137.5 pg/ml respectively) with a subsequent small decrease. No differences between the groups could be observed at any time point with respect to vasoactive substances, urine output (CON 6.5 ml/min and PULS 6.2 ml/min) or haemodynamics during CPB. This confirms studies emphasizing that no effective microvascular pulsatile flow is generated by conventional pulsatile flow-generating devices. In the present study, normothermia and a constant flow rate were maintained during CPB. Aortic cannulae (body-surface-related not maximal large diameters) were inserted. Altering these procedures may have led to more pronounced differences between the groups. All patients had an uneventful course after the operation. Similar to other reports, the present study was not able to demonstrate any benefit of pulsatile perfusion during extracorporeal circulation.

Aged↗
PubMed1995

RETRACTED: Do plasma levels of circulating soluble adhesion molecules differ between surviving and nonsurviving critically ill patients?

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the editor In 2018, CHEST published a notice1 that all articles authored by Joachim Boldt be read with caution due to expressions of concern about falsified data. In 2020, CHEST received additional evidence of research misconduct and breaches of scientific integrity that were discovered following an investigation by the author's former institution, the University of Giessen2. In light of this new evidence, this article has been retracted by CHEST. 1. Irwin, R.S., MD, Master FCCP. Notice From the Editor in Chief. CHEST 153(3), p. 767. 2. Mukherjee, J. Statement on the scientific credibility of articles published by Joachim Boldt, formerly professor at Justus Liebig University (JLU), Giessen, Germany. https://ars.els-cdn.com/content/image/1-s2.0-S000709122030163X-mmc3.pdf.

Adult↗
PubMed1995

The effects of thiopentone, etomidate, ketamine and midazolam on several bactericidal functions of polymorphonuclear leucocytes in vitro.

Polymorphonuclear leucocytes (PMNL) are an essential component of the defence system against invading bacteria. There is evidence that some anaesthetics are able to suppress PMNL functions, promoting, perhaps, perioperative infection. We studied the effects of thiopentone, etomidate, ketamine, and midazolam on the generation of bactericidal agents (superoxide anion, hydrogen peroxide, and myeloperoxidase) by PMNL in vitro. Thiopentone inhibited superoxide anion (P < or = 0.01) as well as hydrogen peroxide production (P < or = 0.001). However, there was no statistically significant effect on myeloperoxidase release. Neither etomidate nor ketamine influenced the PMNL functions tested to any extent. Midazolam suppressed superoxide anion generation (P < or = 0.01) but only if a concentration far beyond clinical relevance was used.

Adult↗
PubMed1995

[Cerebral oximetry by infrared spectroscopy in comparison with continuous measurement of oxygen saturation of the jugular vein bulb in interventions of the internal carotid artery].

OBJECTIVE: Monitoring the central nervous system during carotid endarterectomy plays an important role in detection of cerebral ischemia. With optical spectroscopy in the near-infrared light range it is now possible to measure regional cerebral oxygen saturation (rSO2) noninvasively. Numerous studies emphasize the importance of cerebral oxygen balance rather than absolute values of cerebral blood flow or metabolic rate. In this study data from oxygen saturation measured in the jugular bulb (SJO2) were compared to rSO2. METHODS: 10 patients undergoing elective carotid end-arterectomy were enrolled after written informed consent and approval by the local ethics committee. rSO2 data were measured by cerebral spectroscopy (INVOS 3100, Somanetics, Michigan/USA). To avoid lesions of the internal carotid artery, a 4-F oxymetry catheter (OPTICATH, Abbot GmbH, Wiesbaden) was placed in the jugular bulb by retrograde approach after preparation by the surgeon. Anaesthesia and mechanical ventilation were standardised. RESULTS: After cross-clamping of the internal carotid artery rSO2 significantly decreased (60.5 +/- 3.5%) compared to baseline (66.0 +/- 1.4%). After declamping rSO2 increased significantly (63.0 +/- 4.2%) and was close to baseline at the end of operation (65.0 +/- 2.8%). The SJO2 time course showed good correlation compared to rSO2 data (r = 0.85). After cross-clamping SJO2 decreased significantly (51.5 +/- 6.3%) in comparison to baseline (59.5 +/- 4.9%). Declamping increased SJO2 to 59.5 +/- 6.3%. No changes in latencies or amplitudes of SEP were observed throughout the operation. CONCLUSIONS: Noninvasive cerebral optical spectroscopy is a useful tool to determine the brain tissue oxygenation. The positive correlation to jugular bulb oxygen saturation is somewhat unexpected as rSO2 evaluates regional while SJO2 measures global oxygen content. However our results suggests that both methods are able to detect episodes of cerebral ischemia during carotid endarterectomy. The interpretation of the changes of cerebral oxygen saturation with respect to neurological outcome warrants further studies.

Aged↗
PubMed1995

[Optimization of ventricular function during anesthesia induction by administering crystalloids and colloids to heart surgery patients].

OBJECTIVE: To describe the changes in cardiac function after administration of three different solutions infused after anesthetic induction. PATIENTS AND METHODS: Thirty-six patients scheduled for elective aortocoronary bypass surgery were randomly distributed into three groups. Over a period of 25 min after anesthetic induction, 12 received 10 ml/kg of Ringer solution (low dose crystalloid group), 12 received 20 ml/kg of Ringer solution (high dose crystalloid group), and 12 received 10 ml/kg of Ringer solution with 10 ml/kg of hydroxi-ethyl-almidon solution 450,000 D, 0.7 substitution grade (group C-HEA). Minute volume, systemic and pulmonary pressures, osmolality of blood and urine, and plasma and urine sodium concentrations were measured before and after infusion of the assigned liquid. RESULTS: In spite of the volume infused, low dose crystalloid group showed a high incidence of oliguria, increased urinary osmolality and decreased sodium in urine. Cardiac and systolic indices and left ventricular work load remained stable after infusion of the assigned liquid in low and high dose crystalloid groups, whereas they increased significantly ion group C-HEA (+23%, +16% and +20%). CONCLUSION: Administration of restricted doses of crystalloids after anesthetic induction favors the retention of water and sodium. Higher doses of crystalloids weaken this effect. However, neither of these two regimens leads to a more effective cardiac work load. A combination of crystalloids and colloids administered immediately after anesthetic induction temporarily improves cardiac performance during surgery.

Aged↗
PubMed1995

[Effect of controlled hypotension using sodium nitroprusside on platelet aggregation].

OBJECTIVE: To determine the influence of sodium nitroprusside (SNP) on platelet aggregation when this agent is used to induce hypotension during surgery. PATIENTS AND METHODS: Spontaneous platelet aggregation (SPA) determined by impedance measurement and induced platelet aggregation (IPA) determined by turbidimetry were studied in 30 subjects scheduled for elective ear, nose or throat surgery. Fifteen patients in the SNP group (SNPG) received SNP in doses adjusted to maintain a mean arterial pressure of 50 mmHg. Another 15 patients who did not receive SNP served as controls. RESULTS: SPA increased progressively in both groups. The greatest increase occurred after anesthetic induction (control group +172%, SNPG +48%); the highest level recorded was reached on the morning of the first day after surgery (control group +215%, SNPG +46%). IPA decreased after anesthetic induction (control group -21%, SNPG -40%) and stayed down throughout surgery. IPA was higher on the first morning after surgery than before the operation (control group +35%, SNPG +2%). SPA was significantly higher 60 minutes after start of surgery than before surgery in the control group; IPA and SPA were likewise higher in these patients the morning after surgery. CONCLUSIONS: Platelet aggregation increases during surgery and in the immediate postoperative period. This increase is attenuated when SPA is given to induce hypotension. SPA should be determined by measurement of impedance in whole blood when the nature of platelet aggregation during surgery is being studied, given that early increases in IPA can be masked as a result of the low sensitivity of turbidimetry.

Blood Coagulation Disorders↗
PubMed1994

Propofol inhibits phagocytosis and killing of Staphylococcus aureus and Escherichia coli by polymorphonuclear leukocytes in vitro.

Polymorphonuclear leukocytes (PMNL) are important components of the immunological defence system which protects the human organism from invading bacteria. Using a fluorescence microscopic method, we examined the influence of propofol and its solvent intralipid on phagocytosis and killing of Staphylococcus aureus and Escherichia coli by PMNL in vitro. Propofol inhibited (P < or = 0.001) phagocytosis of Staphylococcus aureus as well as Escherichia coli. Killing of Staphylococcus aureus (P < or = 0.001) and of Escherichia coli (P < or = 0.01) was suppressed. Intralipid, by itself, impaired phagocytosis of Escherichia coli (P < or = 0.05). Apart from that, intralipid produced no relevant effects. Additional clinical studies regarding the influence of propofol on PMNL function are recommended.

Adult↗
PubMed1994

Thrombomodulin in pediatric cardiac surgery.

In 30 consecutive children with congenital heart disease scheduled for pediatric cardiac operations, thrombomodulin, protein C, free protein S, and thrombin-antithrombin complex were measured by enzyme-linked immunosorbent assay after the induction of anesthesia (baseline value), and then before, during, and after cardiopulmonary bypass until the first postoperative day. The patients were divided prospectively into two groups: children weighing less than 10 kg (group 1; n = 15) and those weighing more than 10 kg (group 2; n = 15). At baseline, the plasma concentration of thrombomodulin was significantly higher in the children in group 1 than in those in group 2 (83.1 +/- 11.0 ng/mL versus 29.2 +/- 12.1 ng/mL). During cardiopulmonary bypass, the thrombomodulin level was reduced in both groups without showing any significant group differences. Five hours after cardiopulmonary bypass and on the first postoperative day, the thrombomodulin level exceeded normal values only in the children weighing less than 10 kg. In both groups, the protein C levels were already below normal at the beginning of the study. The baseline protein S concentration was higher in the smaller children (80% +/- 18%) than in the larger children (66% +/- 11%). It was reduced by cardiopulmonary bypass in both groups; however, postoperatively it did not return to normal in group 1 (45.1% +/- 10%). Plasma levels of the thrombin-antithrombin complex were similar in both groups, with a marked increase at the end of cardiopulmonary bypass, and returned to near-normal levels by 5 hours after bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1994

RETRACTED: Does aprotinin influence endothelial-associated coagulation in cardiac surgery?

Aprotinin has been reported to reduce bleeding in cardiac surgery patients. Its mechanisms of action on coagulation have not been fully elucidated. In a prospectively randomized study of 40 patients undergoing elective aortocoronary bypass grafting, the influence of high-dose aprotinin (2 million IU of aprotinin before CPB, 500,000 IU/h until the end of operation, 2 million IU added to the prime) (N = 20) on endothelial-related coagulation was compared to a nontreated control group (N = 20). Thrombomodulin (TM), protein C and (free) protein S as well as thrombin/antithrombin-III (TAT) plasma concentrations were measured by enzyme-linked immunosorbent assays (ELISA) before the aprotinin infusion, before cardiopulmonary bypass (CPB), during CPB and after CPB, at the end of surgery, 5 hours after CPB, and on the first postoperative day. All standard coagulation parameters (AT-III and fibrinogen plasma levels, platelet count, partial thromboplastin time) did not differ between the two groups. At baseline, TM plasma levels were within the normal range (< 40 ng/mL) and similar in both groups. During CPB, TM plasma concentrations decreased similarly in both groups (aprotinin: 18 +/- 6 ng/mL, control: 17 +/- 7 ng/mL) followed by a comparable increase in the postbypass period until the first postoperative day (aprotinin: 60 +/- 10 ng/mL, control: 53 +/- 11 ng/mL). Protein C and (free) protein S plasma levels also showed no differences between the two groups. On the first postoperative day, baseline values for protein C and protein S had not yet been reached.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1994

RETRACTED: Volume loading with hypertonic saline solution: endocrinologic and circulatory responses.

Hypertonic saline solution appears to be an attractive method of volume expansion. In 45 patients undergoing elective aorto-coronary bypass grafting, endocrinologic and circulatory responses to volume loading with hypertonic saline solution prepared in low molecular weight (MW) hydroxyethyl starch (HES) solution (72 g/L NaCl, HES concentration: 6%; MW: 200,000 D; degree of substitution [DS]: 0.5) (HS-HES) was compared randomly to patients who had received low molecular weight HES solution (LMW-HES). A group of patients without volume loading served as a control. Volume was infused to double the low pulmonary capillary wedge pressure (PCWP < 5 mmHg) after induction of anesthesia. Plasma levels of atrial natriuretic peptide (ANP), endothelin, vasopressin, and catecholamines were measured before, during, and after cardiopulmonary bypass (CPB) until the first postoperative day. In addition to systemic circulatory changes, capillary skin blood flow was measured by laser Doppler flowmetry. ANP plasma concentration increased in both volume groups (HS-HES: +79%; HES: +32%), whereas it decreased in the control (-20%). Infusion of HS-HES resulted in an increase in plasma endothelin concentration before and after CPB (from 3 to 6 pg/mL). Five hours after CPB, both treatment groups had higher endothelin plasma concentrations than the control patients (P < 0.05). Epinephrine and norepinephrine plasma levels increased most markedly in the control patients and were highest in the postbypass period in these patients. CI increased most after infusion of HS-HES (+65%) (P < 0.05). In the postbypass period, CI remained significantly higher in both volume groups than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Natriuretic Factor↗
PubMed1994

[Topographic changes in cerebral electric activity after premedication with flunitrazepam].

AIM: The effects on cerebral function of premedication with the benzodiazepine flunitrazepam and with morphine were studied on the evening of the preoperative day (2 mg flunitrazepam p.o.) and 90 minutes before induction of anaesthesia (2 mg flunitrazepam plus 15 mg morphine i.m.). DESIGN: The EEG was analysed topographically (17 electrodes) and quantitatively. RESULTS: As a typical effect of benzodiazepines, increases in electrical activity in the frequency band beta-1 of the power spectrum were observed, and could be demonstrated 10 minutes after oral application, mainly in the frontal and central parts of the cortex. Increases in the powerbands delta and theta indicated induction of sleep approximately 15-20 minutes after application and were not looked upon as an effect of the benzodiazepine exclusively. These increases were noticed first in the central, occipital and temporal areas and after 30 minutes in the frontal parts of the cortex. Flunitrazepam plus morphine showed qualitatively similar but quantitatively less pronounced results. Topographical differences were similar to the results of an application of flunitrazepam alone. DISCUSSION: The results demonstrate the importance of a topographical as well as quantitative evaluation in studies on complex interactions of sedative or narcotic drugs and their clinical effects on cerebral function.

Administration, Oral↗