PubMed Health⌕ Search

Biomedical subjects

W Buhre

Publications and source records attributed to W Buhre.

At least 19 recordsLinked to original sources
PubMed2006

[Pulmonary artery catheter in anaesthesiology and intensive care medicine].

The indication for the use of the pulmonary artery catheter (PAC) in high-risk patients is still a matter of discussion. Observational studies suggested that the use of the PAC did not result in decreased mortality but may even lead to increased mortality and morbidity. Therefore, a number of randomized controlled trials have been performed throughout recent years in patients suffering from sepsis/ARDS, congestive heart failure, multi-organ failure and those undergoing high-risk non-cardiac surgery. The majority of recent randomized studies failed to demonstrate any benefit of the PAC with respect to mortality and morbidity. However, the use of the PAC was also regularly not associated with an increase in morbidity and/or mortality. This review gives an overview of measurement parameters obtained by the current generation of PACs, alternatives to the PAC and recent studies on the use of the PAC in clinical practice.

Anesthesiology↗
PubMed2006

Intra- and extravascular volume status in patients undergoing mitral valve replacement: crystalloid vs. colloid priming of cardiopulmonary bypass.

BACKGROUND AND OBJECTIVE: Cardiopulmonary bypass is associated with changes of intra- and extravascular volume status often resulting in cardiopulmonary dysfunction. The purpose of this prospective double-blind study was to evaluate the influence of different priming solutions of the extracorporeal circuit on intra- and extravascular volume status and haemodynamics in patients undergoing elective mitral valve replacement. METHODS: Twenty-two patients with mitral valve insufficiency were randomly allocated into two equal groups. In Group 1 cardiopulmonary bypass was primed with a nearly isooncotic solution consisting of 4% albumin. The second group received a pure crystalloid priming solution. The thermo-dye indicator dilution technique was used for the assessment of cardiac output, central and pulmonary blood volume, right ventricular end-diastolic volume and total blood volume. RESULTS: Patients in the crystalloid group showed increased intraoperative fluid requirements. Significantly more fluid was accumulated in the extravascular space whereas total blood volume was decreased after surgery. Stroke volume index (SVI) was significantly decreased in the immediate postoperative period when compared to baseline. As indicated by the increase in extravascular fluid content after surgery, both colloid and crystalloid priming volumes were transferred to the extravascular space. CONCLUSION: The use of colloid priming solutions in patients with mitral valve insufficiency leads to less fluid requirements and significantly reduced fluid shift in the interstitium. However, these changes are not associated with changes in haemodynamic parameters or short term outcome.

Adrenergic beta-Agonists↗
PubMed2005

[Preoperative long-term therapy].

A large number of patients undergoing elective surgical procedures already take routine medication preoperatively. The majority of these patients use drugs for therapy of preexisting cardiovascular, pulmonary or endocrinological diseases which are independent of the planned surgical procedure. The number and type of preoperative drug therapy are correlated to age, gender and co-morbidity of the patients. Furthermore, patients with higher ASA-classes usually take more drugs, as they suffer from several medical diseases. Information about the perioperative handling of routine drug therapy is important for the planning of anaesthesia and surgery. A close cooperation of all medical specialities involved is necessary, in particular when patients take anticoagulants or other substances which should be withdrawn or replaced. This review focuses on the handling of routine preoperative medication by the anaesthesiologist in the light of available literature.

Anesthesia↗
PubMed2005

Influence of intra-aortic balloon pumping on cerebral blood flow pattern in patients after cardiac surgery.

BACKGROUND AND OBJECTIVE: The effects of intra-aortic balloon pumping (IABP) on cerebral perfusion are still a matter of debate. End-diastolic reversal of blood flow in cerebral arteries has been observed in a small number of patients. We prospectively investigated the incidence and the amount of transient cerebral artery blood flow reversal during balloon pumping in patients recovering from cardiac surgery. METHODS: In 23 patients receiving IABP support, blood flow velocities in the right middle cerebral artery were assessed by transcranial Doppler-sonography. Additionally, systemic haemodynamics were monitored. In each patient, measurements were performed at three different pump settings: without support, assist ratio 1 : 1 and assist ratio 1 : 2. RESULTS: In 8 of 23 patients, balloon pumping caused a transient diastolic reversal of blood flow in the middle cerebral artery during balloon deflation. Antegrade mean flow velocity in the middle cerebral artery significantly increased from 57 +/- 27 to 61 +/- 26 (assist ratio 1 : 1) and 61 +/- 29 cm s(-1) (assist ratio 1 : 2) (P < 0.05). Taking transient blood flow reversal into account, net mean flow velocity did not increase with balloon pump support. Systemic haemodynamic parameters remained unchanged. CONCLUSION: Left ventricular support with IABP significantly changed flow patterns in basal cerebral arteries of our patients. In 35% of patients, support resulted in a transient reversal of intracranial blood flow which counterbalanced a slight increase in mean antegrade flow.

Aged↗
PubMed2005

Influence of venous drainage and hemofiltration on hypercirculatory instability after high volume crystalloid cardioplegia during coronary artery bypass surgery.

AIM: The etiology of hypercirculatory instability following cardiac surgery with cardiopulmonary bypass has not yet been completely investigated and its clinical impact remains unclear. This prospective study was undertaken in order to investigate the impact of the systemic infusion of high volume crystalloid cardioplegia on the incidence of hypercirculatory instability and inflammatory mediator release in patients undergoing coronary artery bypass grafting. METHODS: Forty patients with single-atrial cannulation (group A), 40 patients with single-atrial cannulation and intraoperative hemofiltration (group B), and 40 patients with bicaval cannulation and complete removal of the cardioplegic solution from the right atrium (group C) were analyzed for hemodynamic changes and inflammatory mediator release until the postoperative day 2. Myocardial protection was performed using 2,000 mL cold crystalloid cardioplegia. RESULTS: A higher incidence of hypercirculatory instability in group A (39.2%) and B (42.8 %) was noted when compared to group C (18%, P = 0.032). Cardiac index was lower in group C when compared with group A (P = 0.001; 95% CI: 4.1, 15.57) and group B (P = 0.02; 95% CI: 1.13, 15.25). Systemic vascular resistance was higher in group C when compared with group A (P = 0.0001; 95% CI: 7108.7, 3131) and group B (P < 0.005; 95% CI 7598.9; 2830.6). High levels of tumor necrosis factor alpha, interleukin-6, interleukin-8, interleukin-10, and intercellular adhesion molecule-1 with no significant differences between the groups were measured early postoperative. CONCLUSIONS: High volume crystalloid cardioplegia under use of single-atrial venous cannulation is associated with a higher incidence of hypercirculatory failure. Hemofiltration during cardiopulmonary bypass offers no benefit on the incidence of hypercirculatory instability and to the release of inflammatory mediators.

Aged↗
PubMed2004

Prediction of fluid responsiveness in patients during cardiac surgery.

BACKGROUND: Left ventricular stroke volume variation (SVV) has been shown to be a predictor of fluid responsiveness in various subsets of patients. However, the accuracy and reliability of SVV are unproven in patients ventilated with low tidal volumes. METHODS: Fourteen patients were studied immediately after coronary artery bypass grafting (CABG). All patients were mechanically ventilated in pressure-controlled mode [tidal volume 7.5 (1.2) ml kg(-1)]. In addition to standard haemodynamic monitoring, SVV was assessed by arterial pulse contour analysis. Left ventricular end-diastolic area index (LVEDAI) was determined by transoesophageal echocardiography. A transpulmonary thermodilution technique was used for measurement of cardiac index (CI), stroke volume index (SVI) and intrathoracic blood volume index (ITBI). All variables were assessed before and after a volume shift induced by tilting the patients from the anti-Trendelenburg (30 degrees head up) to the Trendelenburg position (30 degrees head down). RESULTS: After the change in the Trendelenburg position, SVV decreased significantly, while CI, SVI, ITBI, LVEDAI, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) increased significantly. Changes in SVI were significantly correlated to changes in SVV (r=0.70; P<0.0001) and to changes in LVEDAI, ITBI, CVP and PAOP. Only prechallenge values of SVV were predictive of changes in SVI after change from the anti-Trendelenburg to the Trendelenburg position. CONCLUSIONS: In patients after CABG surgery who were ventilated with low tidal volumes, SVV enabled prediction of fluid responsiveness and assessment of the haemodynamic effects of volume loading.

Aged↗
PubMed2004

Xenon modulates neutrophil adhesion molecule expression in vitro.

BACKGROUND AND OBJECTIVE: Xenon reduces the infarct size after regional ischaemia in the rabbit heart in vivo, but the underlying mechanisms are unknown. Since adhesion molecules on neutrophils are closely involved in the pathophysiology of ischaemia/reperfusion injury and modulation of neutrophil function, we investigated the effect of xenon on neutrophil adhesion molecule expression in vitro. METHODS: Freshly isolated neutrophils were incubated with 30% or 60% xenon for 60 min. In unstimulated and after stimulation with either N-formyl-methionyl-leucyl-phenylalanine or phorbol-12-myristate-13-acetate neutrophil surface expression of PSGL-1, L-selectin, CD11a and CD11b were measured by flow cytometry. RESULTS: At both concentrations, xenon reduced the surface expression of PSGL-1 by 10% (P < 0.05), and of L-selectin by 15% (P < 0.05) in the 60% xenon group. Furthermore, N-formyl-methionyl-leucyl-phenylalanine activated neutrophils showed an increased removal of L-selectin from the neutrophil surface following incubation with xenon (30% compared to controls, P < 0.05). Neutrophil beta2-integrin expression was not altered by xenon. CONCLUSIONS: Xenon increases the removal of the selectins PSGL-1 and L-selectin from the neutrophil surface in vitro. Since both selectins are involved in the initial contact between neutrophils and endothelial cells, xenon may affect neutrophil adhesion to endothelium during ischaemia/reperfusion injury. However, because the beta2-integrin expression was unaffected by xenon, further investigations are required to clarify whether xenon may modulate neutrophil transmigration through endothelial cells in vivo.

Anesthetics, Inhalation↗
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

Extrapolation to zero-flow pressure in cerebral arteries to estimate intracranial pressure.

BACKGROUND: Cerebral perfusion pressure (CPP) is commonly calculated from the difference between arterial blood pressure (AP) and intracranial pressure (ICP). ICP can be considered the effective downstream pressure of the cerebral circulation. Consequently, cerebral circulatory arrest would occur when AP equals ICP. Estimation of AP for zero-flow pressure (ZFP) may thus allow estimation of ICP. We estimated ZFP from cerebral pressure-flow velocity relationships so that ICP could be measured by transcranial Doppler sonography. METHODS: We studied 20 mechanically ventilated patients with severe head injury, in whom ICP was monitored by epidural pressure transducers. AP was measured with a radial artery cannula. Blood flow velocity in the middle cerebral artery (V(MCA)) ipsilateral to the site of ICP measurement was measured with a 2 MHz transcranial Doppler probe. All data were recorded by a microcomputer from analogue-digital converters. ZFP was extrapolated by regression analysis of AP-V(MCA) plots and compared with simultaneous measurements of ICP. RESULTS: ZFP estimated from AP-V(MCA) plots was linearly related to ICP over a wide range of values (r=0.93). There was no systematic difference between ZFP and ICP. Limit of agreement (2 SD) was 15.2 mm Hg. Short-term variations in ICP were closely followed by changes in ZFP. CONCLUSION: Extrapolation of cerebral ZFP from instantaneous AP-V(MCA) relationships enables detection of severely elevated ICP and may be a useful and less invasive method for CPP monitoring than other methods.

Blood Pressure↗
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↗
PubMed2001

[The cardiac risk patient in anesthesia].

Perioperative cardiac morbidity is one of the main challenges to the anaesthesiologist. Because of demographic changes and the increased prevalence of coronary artery disease (CAD) in elderly patients, the number of those at risk is increasing. Special attention has to be paid to patients bearing an increased risk where CAD has not been proven preoperatively because they represent the majority. The use of the "Revised Cardiac Risk Index", which includes patient-related as well as surgery-related risk, is recommended as its predictive value is validated to be very high. Additional preoperative testing is indicated only in those patients at intermediate risk where functional status is poor or unclear. In those with clearly high risk, possibility and urgency of an intervention related to their cardiac disease must be weighed against urgency and invasiveness of planned non-cardiac surgery. Regarding prophylactic perioperative therapy, only beta-blockers can be recommended on a sufficient basis of clinical data. This treatment is of special value in patients with poor functional status and those undergoing vascular surgery. Postoperative continuation of beta blockade for five to seven days is essential to its success. The usefulness of alpha-2-blockers is not equally well-proven so far. Prevention of perioperative hypothermia can reduce cardiac risk. In addition, there is increasing evidence that thoracic epidural anaesthesia decreases cardiovascular morbidity and mortality.

Anesthesia↗
PubMed2001

Blood flow velocities in the basal vein after subarachnoid haemorrhage. A prospective study using transcranial duplex sonography.

BACKGROUND: Early recognition of emerging delayed neurological deficits (DND) in patients after subarachnoid haemorrhage (SAH) is not always possible by transcranial Doppler sonography. Aim of this study was to investigate a) whether determination of blood flow velocities in deep cerebral basal veins can predict DND in these patients b) the correlation of venous flow velocity to cerebral blood flow (CBF). METHODS: a) We prospectively investigated the mean flow velocity in the basal vein (VBVR), in the middle cerebral artery (VMCA) and in the extracranial internal carotid artery (VICA) in 66 patients after spontaneous SAH. Examinations were performed daily during the first 10 days, using transcranial duplex sonography. Thirty-seven patients had VMCA exceeding 120 cm/s. They were categorised in three groups: 1: no delayed neurological deficit; II: transient DND; III: permanent DND or death associated with vasospasm. b) In another group of 14 patients, interdiane variations in global cerebral blood flow (CBF) measured by the Kety-Schmidt-method were correlated with variations in VBVR, VMCA, and VICA. FINDINGS: a) In patients without deficit, VBVR was significantly elevated above normal values the first day (p < 0.05), and days 5 and 6 (p < 0.1) after VMCA exceeding 120 cm/s. In group III (permanent deficit), flow velocities in the BVR were significantly below normal on day 5 (p < 0.05) and 9 (p < 0.1). b) The correlation between changes in VBVR to changes in CBF (r = 0.78, p < 0.001) was closer than between changes in VMCA to the changes in CBF (r = 0.54, p < 0.05). INTERPRETATION: In case of elevated VMCA, patients with higher VBVR seem to have a better outcome. Changes in CBF correlate better with VBVR than with arterial flow velocities.

Adult↗
PubMed2001

Pathogenetic mechanisms of venous congestion after the Fontan procedure.

BACKGROUND: The hemodynamic status after a Fontan type procedure for definitive palliation of functionally univentricular hearts is dominated by a high central venous pressure, which seems to be one of several factors responsible for venous congestion appearing as a frequent complication in the early and late postoperative course. The purpose of our study was to find other hemodynamic parameters correlating with the presence of venous congestion and effusions in these patients. METHODS: We compared the hemodynamic data of 18 patients who had an uneventful long-term course after a Fontan type procedure with the respective data of 10 patients who developed symptoms of venous congestion in the immediate postoperative period. Based on a theoretical model, we developed an algorithm to calculate mean hydrostatic capillary pressure from mean arterial pressure, systemic vascular resistance index and central venous pressure. RESULTS: Pulmonary vascular resistance index (2.1 +/- 1.0 mmHg L-1 min m2), mean left atrial pressure (9.7+/-4.0 mmHg) and cardiac index (3.6+/-0.6 l/min/m2) are mainly normal in patients with venous congestion in the immediate postoperative period, but mean hydrostatic capillary pressure is significantly higher compared to patients without venous congestion (24.3+/-3.1 vs 18.3+/-4.0 mmHg). Lower mean hydrostatic capillary pressures in these patients are due to a highly significant increase of systemic vascular resistance index (18.6+/-4.2 versus 33.6+/-6.6 mmHg L-1 min m2) and a concomitant decrease of cardiac index to 2.4+/-0.3 l/min/m2. CONCLUSIONS: The increase of mean hydrostatic capillary pressure, caused by high central venous pressures but also by relatively low systemic vascular resistance indexes, seems to be the hemodynamic key parameter responsible for venous congestion and effusions in patients after a Fontan type procedure in the immediate postoperative period.

Adolescent↗
PubMed2001

Changes in cardiac output and intrathoracic blood volume: a mathematical coupling of data?

BACKGROUND: Measurements of intrathoracic blood volume (ITBV) provide volumetric information about cardiac preload and are used to investigate the cause of alterations in cardiac output (CO). On the other hand, CO is required to calculate ITBV. Thus, concerns have been raised with respect to a mathematical coupling of data. The aim of this prospective, clinical study was to investigate whether a variation in CO induced by high-dose beta-blockade influences thermodilution measurements of ITBV in the absence of changes in intravascular volume in patients undergoing minimally invasive coronary artery bypass grafting. METHODS: Sixteen patients undergoing elective minimally invasive direct coronay artery bypass (MIDCAB) surgery were studied. Transpulmonary thermodilution measurements of ITBV and CO were simultaneously performed before bypass grafting, during beta-blockade induced by high-dose esmolol and at the end of surgery. RESULTS: During esmolol administration, CO significantly decreased by 33%, whereas ITBV remained unchanged compared to control values (876+/-46 ml m-2 during control versus 860+/-61 ml m-2 during esmolol administration). After the end of esmolol administration, CO significantly increased by 79%. Again, ITBV remained virtually unchanged (860+/-61 ml m-2 during esmolol administration versus 911+/-38 ml m-2 after esmolol administration). CONCLUSIONS: The results of the present study demonstrate that substantial alterations in CO as a consequence of high-dose esmolol infusion are not associated with changes in ITBV. Because haemodynamic changes were induced by factors other than variation of preload, these findings suggest that changes in cardiac output do not influence thermodilution measurements of ITBV in this setting.

Adrenergic beta-Antagonists↗
PubMed2001

Assessment of cardiac preload by indicator dilution and transoesophageal echocardiography.

BACKGROUND AND OBJECTIVE: Assessment of cardiac preload is of major importance in the management of critically ill patients. Echocardiographic determined left ventricular end-diastolic area and indicator dilution derived intrathoracic blood volume are used as surrogates for cardiac preload. However, no controlled comparison studies on the relationship between induced changes in end-diastolic area and intrathoracic blood volume and concomitant changes in stroke volume index are available. METHODS: The effects of a change in body position on these variables were investigated in 10 anaesthetized patients. RESULTS: Intrathoracic blood volume and end-diastolic area decreased by 18 +/- 11% and 27 +/- 13% respectively. Stroke volume index concomitantly decreased by 19 +/- 11%. Correlation analysis revealed a close relation between stroke volume index and intrathoracic blood volume (r=0.75) and end-diastolic area (r=0.76). CONCLUSIONS: Within the observed range of data, intrathoracic blood volume and end-diastolic area are equivalent indices of cardiac preload.

Adult↗
PubMed2001

Reliability of cerebral blood flow measurements by transcerebral double-indicator dilution technique.

BACKGROUND AND OBJECTIVE: The recently developed transcerebral double-indicator dilution technique has proven to be a feasible monitoring alternative to measure global cerebral blood flow at the bedside. However, the short-term repeatability of transcerebral double-indicator dilution measurements has not yet been investigated. The present study was designed to investigate the accuracy in terms of reliability for repeated transcerebral double-indicator dilution measurements to assess global cerebral blood flow during a definite carbon dioxide challenge in a clinical trial. METHODS: The investigation was performed in 10 patients scheduled for elective coronary artery bypass grafting. After induction of anaesthesia, repeated cerebral blood flow measurements using transcerebral double-indicator dilution were performed during target normocapnia, hypocapnia and hypercapnia. For transcerebral double-indicator dilution measurements, a bolus injection of ice-cold indocyanine green was administered into a central vein. The resulting thermal dye dilution curves were recorded simultaneously in the aorta and the jugular bulb using combined fibreoptic thermistor catheters. Cerebral blood flow was calculated from the mean transit times of the indicators through the brain. Additionally, transcranial Doppler sonography was simultaneously performed to measure transient changes in the cerebral blood flow velocity. RESULTS: Transcerebral double-indicator dilution measurements revealed a reasonable coefficient of repeatability with 9.1, 9.7 and 20.2 mL min-1 100 g-1 during normo-, hypo- and hypercapnic conditions, respectively. However, a total of 20% of the administered measurements had to be rejected for methodological reasons. CONCLUSIONS: Repeated measurements with the transcerebral double-indicator dilution method show a reasonable repeatability. With consideration to the limitations of the transcerebral double-indicator dilution technique, this new method proves to be a reliable monitoring tool to measure global cerebral blood flow at the bedside.

Aged↗