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Biomedical subjects

D De Backer

Publications and source records attributed to D De Backer.

At least 19 recordsLinked to original sources
PubMed2003

Lactic acidosis.

The detection of tissue hypoxia and its correction is one of the aim of the hemodynamic monitoring. Classical hemodynamic variable often fail to achieve this goal. Lactate measurements may be a good indicator of tissue hypoxia. Selected review of the articles on lactate in critically ill patients. Tissue hypoxia is associated with an increase in blood lactate levels. However lactate can also be produced in aerobic conditions, in inflammated tissues, and lactate clearance is often decreased in critically ill patients. Whatever its origin, blood lactate levels have a strong predictive value. The interpretation of blood lactate levels is difficult. Nevertheless, monitoring blood lactate levels can be useful to detect tissue hypoxia and to monitor the effects of therapy.

Acidosis, Lactic↗
PubMed2003

Stroke volume variations.

During the cyclic changes in intrathoracic pressure, changes in stroke volume characterize the state at which both ventricles are preload dependant. Determining stoke volume variations may thus help to predict fluid responsiveness in mechanically ventilated patients. Selected review of the articles having investigated the stroke volume variations in critically ill patients. Stroke volume variations can effectively predict preload dependency in mechanically ventilated patients. Stroke volume can either be measured directly or estimated using the analysis of the arterial pressure waveform. Alternatively, pulse pressure variations can be calculated. However, these index are sensitive to tidal volume. During mechanical ventilation with low tidal volumes, the ventilatory-induced changes in preload may be too small to generate changes in stroke volume, even in preload dependant patients. Stroke volume variations can be useful to detect fluid responsiveness in mechanically ventilated patients.

Heart↗
PubMed2003

OPS techniques.

Microcirculatory alterations have been widely described in experimental models of sepsis, however the microcirculation have long been neglected in septic patients as traditional techniques do not allow the visualisation of the microcirculation. The Orthogonal Polarization Spectral (OPS) imaging technique allows the direct visualisation of the microcirculation at the bedside. A selected review of the articles on the microcirculation in patients with sepsis using the OPS imaging technique, is made. Patients severe sepsis present a decrease in capillary density and a decrease in the proportion of the perfused capillaries. The severity of these alterations is more pronounced in non survivors than in survivors, and is related with the development of multiple organ failure. These alterations can be reversed by vasodilators, either topically applied or administered intravenously. Microvascular blood flow alterations are frequently observed in patients with sepsis and can have major pathophysiological implications.

Capillaries↗
PubMed2002

Undiagnosed rupture of right hemidiaphragm--hepatothorax: a case report.

A case of late diagnosis of right diaphragmatic rupture due to blunt trauma is presented. Traumatic diaphragmatic rupture is an uncommon but severe problem in a patient with multiple injuries. One third of left-sided ruptures and half of right-sided ruptures have been undetected for several days. Traumatic diaphragmatic rupture should be suspected on the basis of an abnormal chest X-ray in patients with multiple injuries. Imaging studies like computed tomography, scan and magnetic resonance imaging can be helpful for differential diagnosis. Right-sided injuries occur more commonly than previously thought and often require thoracotomy.

Adult↗
PubMed2002

[The intensive care department].

Intensive Care Departments are designed for the care of the critically ill, and are equipped with all the material necessary for monitoring and treatment, as well as specially trained medical, nursing, and paramedical staff. With a team of more than 170 highly qualified staff, the Department of Intensive Care at Erasme Hospital, has acquired a national and international reputation in the fields of clinical and experimental research and education, as well as for its standards of clinical practice. Clinical and experimental studies have been high in quantity and quality, and have covered all the key areas in the field of intensive care medicine: severe sepsis, multiple organ failure, transport and metabolism of oxygen, systemic and regional hemodynamic alterations (pulmonary, cerebral, hepato-splanchnic,...), metabolic disorders,... not forgetting issues associated with the complexities of medical ethics. The quality of care, clinical, scientific and personal, offered by the Department of Intensive Care at Erasme Hospital has earned it the high level reputation for which it is renowned in Belgium, and indeed worldwide.

Belgium↗
PubMed2001

The hepatosplanchnic area is not a common source of lactate in patients with severe sepsis.

OBJECTIVE: To investigate the role of the splanchnic region in the hyperlactatemia of septic patients. DESIGN: Prospective, observational study. SETTING: Thirty-one-bed mixed medicosurgical intensive care unit. PATIENTS: Ninety invasively monitored and mechanically ventilated patients with severe sepsis. MEASUREMENTS AND MAIN RESULTS: Splanchnic lactate balance was measured in all patients. Splanchnic blood flow was determined by using the primed continuous indocyanine green infusion technique in 69 patients. In 71 patients, gastric mucosal Pco2 and the Pco2 gap (the difference between gastric and arterial Pco2) also were determined by using gas tonometry with an automated gas analyzer. In each patient, arterial, mixed-venous, and hepatic venous blood samples were obtained to determine hemoglobin oxygen saturations and lactate concentrations. Arterial and hepatic venous lactate concentrations were determined in triplicate and were averaged, and the arterial hepatic venous difference in lactate and lactate consumption were calculated. The splanchnic region produced lactate in only six of the 90 patients. Mean arterial pressure, cardiac index, arterial lactate, hepatic venous oxygen saturation, and catecholamine use were similar in the six patients with splanchnic lactate production and in the 84 others. The arterial hepatic venous differences in lactate and splanchnic lactate consumption were related directly to arterial lactate concentrations (y = 0.073x + 0.209, r(2) =.06, p <.05, and y = 0.06x + 0.183, r(2) =.08, p <.05, respectively) but were not related to Pco2 gap, to the gradient between mixed-venous and hepatic venous oxygen saturations, or to bilirubin concentrations. CONCLUSIONS: Splanchnic lactate release is uncommon in septic patients, even when hyperlactatemia is severe.

APACHE↗
PubMed2001

Effects of alpha - and beta -adrenergic stimulation on hepatosplanchnic perfusion and oxygen extraction in endotoxic shock.

OBJECTIVE: To examine the effects of adrenergic stimulation on hepatosplanchnic perfusion, oxygen extraction, and tumor necrosis factor-alpha production during endotoxic shock. DESIGN: In vivo, prospective, randomized, controlled, repeated-measures, experimental study. SETTING: Experimental physiology laboratory in a university teaching hospital. SUBJECTS: Twenty-one anesthetized and mechanically ventilated dogs. INTERVENTIONS: An intrapericardial catheter was positioned. Catheters for blood sampling were inserted into the right femoral artery, hepatic vein, portal vein, and pulmonary artery. Ultrasonic flow probes were placed around the portal vein, the hepatic artery, the mesenteric artery, the left renal artery, and the left femoral artery. Animals received 2 mg/kg of Escherichia coli endotoxin, followed by fluid resuscitation. Seven dogs received intravenous isoproterenol (0.1 microg/kg x min(-1)), seven received phenylephrine (1 microg/kg x min(-1)), and seven served as controls. Thirty minutes later, cardiac tamponade was introduced to study organ perfusion and tissue oxygen extraction capabilities. MAIN RESULTS: The isoproterenol group had a higher cardiac index and stroke index and lower systemic vascular resistance than the other groups. The phenylephrine group had a higher arterial pressure but a lower cardiac index than the isoproterenol group. The isoproterenol group had a higher hepatic artery blood flow than the other groups and a higher portal and mesenteric flow than the control group. Liver and gut mucosal blood flow was greater in the isoproterenol than in the phenylephrine group. The isoproterenol group had a lower global critical oxygen delivery than the other groups (8.8 +/- 1.3 vs. 13.1 +/- 2.0 (control) and 11.8 +/- 3.3 mL/kg x min(-1) (phenylephrine); both p < .05) and a higher liver critical oxygen extraction ratio than the control group. Isoproterenol tended to attenuate, but phenylephrine significantly increased, blood tumor necrosis factor levels. CONCLUSIONS: During endotoxic shock, beta-stimulation can improve hepatosplanchnic perfusion and enhance tissue oxygen extraction capabilities, whereas alpha-stimulation does not. In addition, alpha-adrenergic stimulation can increase tumor necrosis factor levels.

Adrenergic alpha-Agonists↗
PubMed2001

Effects of dobutamine on hepato-splanchnic hemodynamics in an experimental model of hyperdynamic endotoxic shock.

Dobutamine infusion has been proposed to increase splanchnic blood flow in septic conditions, but its' effects on liver blood flow and metabolism have not been well defined. We investigated the effects of dobutamine on liver blood flow, metabolism, and pathology in a canine hyperdynamic endotoxic shock model. Twenty-one dogs were anesthetized and paralyzed. After the administration of 2 mg/kg endotoxin, normal saline was infused to restore the pulmonary artery-occluded pressure to 10 mmHg. The dogs were then randomized to receive fluids either alone (n = 7) or combined with a dobutamine infusion at a rate of 5 (n = 7) or 10 microg/kg per min (n = 7). After initial fluid resuscitation, cardiac index (CI) increased from 152+/-48 to 386+/-97 mL/kg per min (P < 0.01) and then slightly decreased with time in the control group, but further increased to 458+/-54 mL/kg per min (P< 0.05) and remained elevated in the group treated with 5 microg/kg per min of dobutamine. Portal vein and hepatic arterial blood flows followed a similar course and increased with fluid resuscitation. Both decreased with time in the control group, but further increased in the dobutamine-treated animals. Liver oxygen delivery (DO2liv) increased with fluids from 2.2+/-2.4 to 3.8+/-1.9 mL/kg per min (P < 0.01) and further increased in the dobutamine-treated animals to 4.1+/-1.2 mL/kg per min. This was associated with an increase in liver oxygen uptake from 1.6+/-1.6 to 2.9+/-1.1 mL/kg per min with fluid resuscitation and a further increase to 4.3+/-1.5 mL/kg per min with dobutamine administration. Lactate consumption and hepatic vein oxygen saturation increased with initial fluid resuscitation and then decreased with time in the control group, but not in the dobutamine-treated animals. Increasing the dose of dobutamine to 10 microg/kg per min did not alter this response. At the end of the experiment, liver tissue samples were obtained for microscopic studies. The histological lesions seen in the control group were unaffected by dobutamine. In conclusion, dobutamine increases liver blood flow and metabolism, but does not affect microscopic findings in this hyperdynamic endotoxic shock model.

Adrenergic beta-Agonists↗
PubMed2001

Assessment of the microcirculatory flow in patients in the intensive care unit.

Various techniques have been used at bedside to assess the microcirculation of critically ill patients, including nailfold videomicroscopy, laser doppler techniques, and orthogonal polarization spectral imaging. Nailfold videomicroscopy was introduced first, but its value may be limited by the extreme sensitivity of nailfold microcirculation to external temperature or vasoconstrictive agents. Laser Doppler techniques can measure gastric or jejunal mucosal blood flow as well as skin and muscle blood flow, but do not take into account blood flow heterogeneity, a major parameter of microcirculation. The recent introduction of orthogonal polarization spectral imaging techniques allows direct visualization of microcirculation in critically ill patients, opening a new area for the investigation of the pathophysiologic processes involved in the hemodynamic alterations of shock states.

Critical Care↗
PubMed2001

Normovolemic hemodilution improves oxygen extraction capabilities in endotoxic shock.

We studied the effects of normovolemic hemodilution on tissue oxygen extraction capabilities in a canine model of endotoxic shock. Eighteen anesthetized and mechanically ventilated dogs underwent normovolemic hemodilution with 6% hydroxyethyl starch solution to reach hematocrit (Hct) levels around 40, 30, or 20% before the administration of 2 mg/kg of Escherichia coli endotoxin. Cardiac tamponade was then induced by repeated injections of normal saline into the pericardial sac to reduce cardiac output and study whole body oxygen extraction capabilities. Whole body critical oxygen delivery was lower in the Hct 20% and 30% groups (8.4 +/- 0.4 and 10.4 +/- 0.7 ml. kg(-1). min(-1), respectively) than in the Hct 40% group (12.8 +/- 0.8 ml. kg(-1). min(-1)) (both P < 0.005). The whole body critical oxygen extraction ratio was higher in the Hct 30% and 20% groups (49.1 +/- 8.2 and 55.2 +/- 4.6%, respectively) than in the Hct 40% group (37.1 +/- 4.4 %) (both P < 0.05). Liver critical oxygen extraction ratio was also higher in the Hct 30% and 20% groups than in the Hct 40% group. The arterial lactate concentrations and the gradient between ileum mucosal PCO(2) and arterial PCO(2) were lower in the Hct 20% and 30% groups than in the Hct 40% group. We conclude that, during an acute reduction in blood flow during endotoxic shock in dogs, normovolemic hemodilution is associated with improved tissue perfusion and increased oxygen extraction capabilities.

Animals↗
PubMed2000

Hemodynamic responses to successful weaning from mechanical ventilation after cardiovascular surgery.

Weaning from mechanical ventilation is usually associated with an increase in oxygen consumption (VO2), which may stress the cardiovascular system. We studied relative changes in the cardiac index and oxygen extraction ratio (EO2) during successful weaning in patients after cardiac surgery (n = 52), cardiac transplantation (n = 17), or abdominal aortic surgery (n = 11). Cardiac index was determined by the thermodilution technique and arterial and mixed venous blood gases were obtained before and 30 min after the start of weaning through a T-piece. The cardiovascular changes were evaluated in 42 patients in whom VO2 (calculated by Fick's equation) increased by more than 10%. Cardiac index increased more after abdominal aortic surgery (from 3.27 +/- 0.77 to 4.44 +/- 0.581 min(-1) m(-2), p < 0.01) than after cardiac surgery (from 2.53 +/- 0.59 to 2.87 +/- 0.46 1 min(-1) m(-2), p < 0.01) or cardiac transplantation (from 2.99 +/- 0.64 to 3.33 +/- 0.741 min(-1) m(-2), p < 0.05). EO2 remained stable in patients after aortic surgery (from 25.9 +/- 7.1 to 25.2 +/- 5.6 %, NS) but increased slightly after cardiac surgery (from 33.3 +/- 6.1 to 37.3 +/- 6.4%, NS) and significantly after cardiac transplantation (from 25.8 +/- 4.1 to 28.2 +/- 4.0%, p < 0.05). Hence the cardiovascular response to weaning from mechanical ventilation may vary according to the type of surgery.

Analysis of Variance↗
PubMed2000

Diaspirin cross-linked hemoglobin improves oxygen extraction capabilities in endotoxic shock.

We studied the effects of diaspirin cross-linked hemoglobin (DCLHb), a cell-free hemoglobin derived from human erythrocytes, on blood flow distribution and tissue oxygen extraction capabilities in endotoxic shock. Eighteen pentobarbital sodium-anesthetized, mechanically ventilated dogs received 2 mg/kg of E. coli endotoxin, followed by saline resuscitation to restore cardiac filling pressures to baseline levels. The animals were randomly divided into three groups: six served as control, six received DCLHb at a dose of 500 mg/kg (group 1) and six DCLHb at a dose of 1,000 mg/kg (group 2). Cardiac tamponade was then induced by saline injection in the pericardial sac to progressively reduce cardiac index and thereby allow study of tissue oxygen extraction capabilities. DCLHb had a dose-dependent vasopressor effect but did not significantly alter cardiac index or regional blood flow. During cardiac tamponade, critical oxygen delivery was 12.8 +/- 0.7 ml. kg(-1). min(-1) in the control group, but 8.6 +/- 0.9 and 8.2 +/- 0.7 ml. kg(-1). min(-1) in groups 1 and 2, respectively (both P < 0.05 vs. control group). The critical oxygen extraction ratio was 39.1 +/- 3.1% in the control group but 58.7 +/- 12.8% and 60.2 +/- 9.0% in groups 1 and 2, respectively. We conclude that DCLHb can improve whole body oxygen extraction capabilities during endotoxic shock in dogs.

Animals↗
PubMed2000

Effects of a hydroxyethylstarch solution on plasma colloid osmotic pressure in acutely ill patients.

Hydroxyethyl starch (HES) solutions can represent an alternative to human albumin solutions in intensive care unit (ICU) patients, but their effects on the plasma colloid osmotic pressure (COP) have not been well defined. We studied the changes in COP in 61 critically ill patients; 39 patients received 500 ml HES 6% (Elo-Haes Fresenius solution) and 22 received 400 ml of a human albumin solution (4% albumin Belgian Red Cross) over 60 to 90 min. COP was determined with an oncometer, using a semi-permeable membrane at 30 Kd, before the infusion, at the end of the infusion, and one hour and four hours after the end of the infusion. COP increased in the HES group from 20.7 +/- 3.1 to 22.5 +/- 3.1 mmHg (p < 0.05), and this increase in COP was sustained throughout the 4 hours of the study. COP did not increase in the human albumin group (from 19.5 +/- 2.4 to 19.9 +/- 2.0 mmHg, NS). Hence, this standard HES solution has greater effects on COP than natural colloids. In view of their lower costs, HES solutions can represent a valuable alternative to human albumin. However, it is necessary to consider the secondary effects of HES and the physiologic functions of albumin.

Adult↗