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Biomedical subjects

A B Groeneveld

Publications and source records attributed to A B Groeneveld.

At least 19 recordsLinked to original sources
PubMed2001

[Adjuvant therapies for sepsis and shock: which are more effective?].

Adjuvant therapy for severe sepsis and shock can be divided into 4 groups. The first group comprises those compounds with proven efficacy in human studies (activated protein C and recombinant bacterial permeability-increasing protein). The second group includes compounds with potential efficacy (heparin), while the third group represents those with no demonstrated efficacy in randomised clinical trials (tumour necrosis factor and interleukin-1 antibodies and receptor antagonists). The fourth group includes those drugs which have been found to be potentially effective in animal studies, but which have not yet been evaluated in humans (i.e., tyrosine kinase inhibitors, selective inducible nitric oxide synthase inhibitors, polyadenosine-diphosphate-ribose-polymerase and caspase III (apoptosis) inhibitors). Formal clinical comparisons between the various treatment options are necessary to assist the clinician in selecting the appropriate form of therapy.

Animals↗
PubMed2001

Granulocyte-macrophage colony-stimulating factor (GM-CSF) decreases left ventricular function. An echocardiographic study in cancer patients.

To study the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the heart, echocardiographic assessments of left ventricular (LV) end-diastolic and end-systolic (ES) diameters (D), ejection fraction (EF) and cardiac output (CO) were done in six male patients (28-70 years of age) with advanced sarcoma (Group 1), prior to (day -1-0), during (day 7-9) and after (day 20-21) a first course of i.v. doxorubicin (day 0) without GM-CSF and a second course (3 weeks after the first one) with GM-CSF 250 microg/m(2)subcutaneously and daily from day 1-11. A similar study was done in ten female patients with advanced breast cancer (31-58 years of age, Group 2) for a first course of doxorubicin+cyclophosphamide with GM-CSF (same schedule as in Group 1). As compared to the mean of values prior to and after the course with GM-CSF in Group 1 and 2, the LVESD during GM-CSF administration transiently increased by median 6% (range -19 to 30%, P<0.05) vs -9% (-21 to 6%, not significant) in the first course without GM-CSF in Group 1 (P<0.05 between courses). The CO and EF tended to decrease during GM-CSF. GM-CSF thus causes a small and transient decrease of LV contractility.

Adult↗
PubMed2001

Assessing heterogeneous distribution of blood flow and metabolism in the heart.

The literature is reviewed on methods to assess heterogeneity of blood flow, substrate uptake and oxidative end energy metabolism in the normal heart, and their interrelations. Even though the factors controlling matching on the regional level remain largely obscure, the evidence that heterogeneous blood flow partially correlates to indicators of metabolism in the normal heart is accumulating, particularly in face of a correlation between acetate metabolism indicative of regional O2 consumption to microsphere blood flow. Moreover, the partial matching cannot be explained by vascular anatomical differences from one region to the other, since, although fractal theory can partially describe the branching patterns of the coronaries, vasodilation is similar among regions upon metabolic stimulation of the heart. It is dissimilar among regions, so that blood flow is redistributed, upon maximum vasodilation with adenosine or hypoxia, denoting regionally different maximum vessel diameter and flow reserve. However, regionally differing tissue composition could also contribute somewhat to regional differences in (the need for) blood flow. It is still unknown, because of technical limitations, how the foregoing measures relate to regional work load.

Animals↗
PubMed2001

Prediction of shock in febrile medical patients with a clinical infection.

OBJECTIVE: Shock in the course of fever is likely caused by septic shock. Because septic shock carries a high mortality rate, early recognition could benefit the patient. We tried to predict the development of shock in medical patients with fever and a clinical infection, on the basis of clinical and microbiological information, and to evaluate the role therein of systemic inflammatory response syndrome (SIRS) criteria: abnormal body temperature, tachycardia, tachypnea, and abnormal white blood cell counts. DESIGN: Prospective observational study. SETTING: Department of Internal Medicine at a university hospital. PATIENTS: Patients were 212 consecutive medical patients with newly onset fever (temperature, >38.0 degrees C axillary or >38.3 degrees C rectally) and a clinical source of infection. MEASUREMENTS AND MAIN RESULTS: Of the 212 patients enrolled, 14 developed shock (i.e., a decrease in systolic arterial blood pressure of >40 mm Hg) during a maximum follow-up period of 7 days after inclusion. In univariate analyses, advanced age, prior urogenital disease, an abdominal source, nosocomial infections, and bacteremia predisposed patients to shock (p < .05). For clinical variables, obtained daily for 2 days after inclusion, a low performance (p < .001), the peak respiratory rate (p < .05), the peak heart rate (p < .05), the nadir score on the Glasgow Coma Scale (p < .005), the peak and nadir white blood cell counts (p < .005), and the nadir albumin (p < .01) and peak creatinine concentrations in blood (p < .001) predicted shock development. In multivariate analysis, the presence of bacteremia, the peak respiratory rate, the nadir Glasgow Coma Scale score, and the peak white blood cell count positively and the peak erythrocyte sedimentation rate negatively contributed to prediction of shock development. In contrast, SIRS had less predictive value, mainly because of lack of predictive value of peak heart rate and temperature in multivariate models. CONCLUSION: In febrile medical patients with a clinical infection, the development of shock involves an interaction between circulating microbial products and the host response, which can be recognized clinically by variables easily obtained at the bedside and partly different from the set used to define SIRS.

Adolescent↗
PubMed2001

alpha-atrial natriuretic peptide, cyclic guanosine monophosphate, and endothelin in plasma as markers of myocardial depression in human septic shock.

OBJECTIVE: To assess the value of alpha-atrial natriuretic peptide (alpha-ANP), second messenger cyclic guanosine monophosphate (cGMP,) and endothelin as markers of myocardial depression in septic shock. DESIGN: Prospective observational study. SETTING: Medical intensive care unit (ICU) of a university hospital. PATIENTS: Fourteen consecutive patients with septic shock and arterial and pulmonary artery catheters in place. MEASUREMENTS AND MAIN RESULTS: Hemodynamic variables and plasma levels of alpha-ANP, cGMP, and endothelin were measured every 6 hrs for 3 days after admission. Eight patients died from shock in the ICU. The nadir left ventricular stroke work index (LVSWI) was below 35 g/m2 in all patients, and the median peak circulating alpha-ANP (n < 68 pg/mL) was 276 pg/mL (range, 79-1056), the median peak cGMP (n < 2.1 ng/mL) was 8.1 ng/mL (range, 3.2-29.7), and the median peak endothelin (n < 5.3 pg/mL) was 15.5 pg/mL (range, 8.5-33.9), supranormal in all patients. Outcome groups differed in the course of cardiac index and LVSWI, which were lower in nonsurvivors despite similar filling pressures and more intensive inotropic treatment (p < .01). The course of alpha-ANP, cGMP, and endothelin plasma levels also differed between groups, with higher levels in nonsurvivors (p < .05). As for pooled data, the mean daily or nadir LVSWI inversely related to mean daily or peak alpha-ANP, cGMP, and endothelin levels, respectively (p < .05). The area under the receiver operating characteristic curve for myocardial depression (LVSWI < 35 g/m2) was for alpha-ANP and endothelin 0.77, and for cGMP 0.85 (p < .01). The optimum cutoff values for alpha-ANP, cGMP, and endothelin were 172 pg/mL, 4.5 ng/mL, and 10.0 pg/mL, respectively. The sensitivity for myocardial depression of alpha-ANP, cGMP, and endothelin was 68%, 77%, and 72%, and the specificity was 82%, 93%, and 69%, respectively. CONCLUSIONS: Circulating alpha-ANP, endothelin, and, particularly, cGMP may be markers of the myocardial depression of human septic shock, which is associated with mortality.

Adult↗
PubMed2001

Gut luminal endotoxin reduces ischemia-reperfusion injury of the small gut in germ-free pigs.

Translocation of luminal bacteria and their products through the intestinal mucosa during ischemia-reperfusion (I/R) may modify I/R injury. To test this hypothesis, 16 germ-free pigs were studied prior to and after clamping the superior mesenteric artery (SMA) and 12 pigs served as controls. Nine pigs in the I/R and 5 in the control group received endotoxin intragastrically, 60 min before baseline. Gut absorption of an inert indicator (polyethyleneglycol [PEG] 3350), gut intraluminal PCO2 (tonometry), and systemic and regional hemodynamic variables were measured up to 4 h after baseline. Gut blood flow was stopped during clamping, some reactive hyperemia occurred up to 30 min after declamping in the I/R groups, independently of prior endotoxin administration. Gut intraluminal-arterial PCO2 gradients were elevated in I/R versus control groups during I and for some time during R, prior endotoxin had no effect. However, in controls without and with luminal endotoxin, PEG urinary excretion, as percentage of the dose administered, was 0.12 +/- 0.12 and 0.17 +/- 0.07, respectively, while it measured 1.82 +/- 0.70 in the I/R group and 0.55 +/- 0.37% in the I/R and endotoxin groups, respectively (P< 0.001). The data suggest that gut luminal endotoxin ameliorates I/R injury of the gut wall in germ-free pigs, without altering changes in gut perfusion adequacy and systemic hemodynamics.

Animals↗
PubMed2001

Circulating inflammatory mediators in patients with fever: predicting bloodstream infection.

The systemic host response to microbial infection involves clinical signs and symptoms of infection, including fever and elevated white blood cell (WBC) counts. In addition, inflammatory mediators are released, including activated complement product C3a, interleukin 6 (IL-6), and the acute-phase reactant secretory phospholipase A(2) (sPLA(2)). To compare the value of the latter with the former in predicting (the degree of) microbial infection at the bedside, we determined clinical variables and took blood samples daily for 3 consecutive days in 300 patients with a new fever (>38.0 degrees C rectally or >38.3 degrees C axillary). Microbiological culture results for 7 days after inclusion were collected. Patients were divided into clinical and microbial categories: those without and with a clinical focus of infection and those with negative cultures, with positive local cultures or specific stains for fungal (n = 13) or tuberculous infections (n = 1), and with positive blood cultures, including one patient with malaria parasitemia. The area under the curve (AUC) of the receiver operating characteristic (ROC) for prediction of positive cultures was 0.60 (P < 0.005) for peak temperature and 0.59 (P < 0.01) for peak WBC count, 0.60 (P < 0.005) for peak C3a, 0.63 (P < 0.001) for peak IL-6, and 0.61 (P < 0.001) for peak sPLA(2). The AUC under the ROC curve for prediction of positive blood cultures was 0.68 (P < 0.001) for peak temperature and 0.56 for peak WBC count (P < 0.05). The AUC for peak C3a was 0.69, that for peak IL-6 was 0.70, and that for sPLA(2) was 0.67 (for all, P < 0.001). The degree of microbial invasion is thus a major determinant of the clinical and inflammatory host response in patients with fever. Moreover, circulating inflammatory mediators such as C3a and IL-6 may help to predict positive blood cultures, together with clinical signs and symptoms of the host response to microbial infection, even before culture results are available. This may help in the designing of entry criteria for therapeutic intervention studies.

Adolescent↗
PubMed2001

Exercise induces gastric ischemia in healthy volunteers: a tonometry study.

Heavy physical exercise may cause gastrointestinal signs and symptoms, and, although splanchnic blood flow may decrease through redistribution by more than 50%, it is unclear whether these signs and symptoms relate to gastrointestinal ischemia. In 10 healthy volunteers, we studied the effect of exercise on gastric mucosal perfusion adequacy using air tonometry. Two relatively short (10 min) exercise stages were conducted on a cycle ergometer, aiming for 80 and 100% of maximum heart rate, respectively. The intragastric-arterial PCO(2) gradient (Delta PCO(2)) was elevated by 1.1 +/- 1.0 kPa over baseline values (-0.1 +/- 0.3 kPa) only after maximal exercise (P < 0.001). Delta PCO(2) positively correlated with the arterial lactate level taken as an index of exercise intensity (Spearman's rank test: r = 0.76, P < 0.0001). By bilinear regression analysis, a lactate level of 12 mmol/l, above which a sharp rise in the Delta PCO(2) occurred, was calculated. We conclude that, in healthy volunteers with normal splanchnic vasculature, gastric ischemia may develop during maximal exercise as judged from intragastric PCO(2) tonometry.

Adult↗
PubMed2000

[PCO2 tonometry of the stomach].

Gastrointestinal luminal tonometry is a minimally invasive technique for measuring gastrointestinal ischaemia. Mucosal ischaemia leads to excessive production of tissue CO2 and thus to an increase of luminal PCO2. For this measurement, a nasogastric catheter is introduced with at its end a balloon permeable for CO2, this balloon is filled with air or liquid. After CO2 has diffused from the tissue into the lumen of the balloon, the PCO2 in the liquid or air is determined. Due to uncertainties about physiological background, methodology and clinical usefulness tonometry is not yet widely applied. The recent introduction of automated airtonometry, replacing the laborious and error-prone manual saline technique, makes tonometry more reliable and easier applicable in the clinical situation. Reliable measurements require inhibition of gastric acid production and measurement in a fasting condition. The lumen-blood PCO2 gradient is the most reliable parameter of gastrointestinal mucosal ischaemia. In the past intraluminal pH--calculated from the intraluminal PCO2 measured by tonometry and the bicarbonate concentration in the blood--has been the parameter most often used. Tonometric parameters are reliable indicators of morbidity and mortality in critically ill patients. The effect of 'tonometry-guided' treatment on the morbidity and mortality is still a matter of debate. Other than using tonometry as a global ('hemodynamic') monitoring device, selective monitoring of the regional perfusion of the digestive tract--such as for diagnostic purpose in suspected chronic ischaemia due to splanchnic arterial disease--is a promising new application area.

Carbon Dioxide↗
PubMed2000

Albumin and artificial colloids in fluid management: where does the clinical evidence of their utility stand?

Key questions remain unresolved regarding the advantages and limitations of colloids for fluid resuscitation despite extensive investigation. Elucidation of these questions has been slowed, in part, by uncertainty as to the optimal endpoints that should be monitored in assessing patient response to administered fluid. Colloids and crystalloids do not appear to differ notably in their effects on preload recruitable stroke volume or oxygen delivery. Limited evidence nevertheless suggests that colloids might promote greater oxygen consumption than crystalloids. It remains unclear, in any case, to what extent such physiological parameters might be related to clinically relevant outcomes such as morbidity and mortality. Recent randomized controlled trial results indicate that, at least in certain forms of fluid imbalance, albumin is effective in significantly reducing morbidity and mortality. Much further investigation is needed, however, to determine the effects of colloid administration on clinically relevant outcomes in a broad range of critically ill patients. The ability of administered colloids to increase colloid osmotic pressure (COP) constitutes one mechanism by which colloids might reduce interstitial oedema and promote favourable patient outcomes. However, the applicability of this mechanism may be limited, due to the operation of compensatory mechanisms such as increased lymphatic drainage. Attempts to increase COP might also be less useful in states of increased vascular permeability such as acute respiratory distress syndrome, although this issue has by no means been settled by empirical data. Colloids are clearly more efficient than crystalloids in attaining resuscitation endpoints as judged by the need for administration of far smaller fluid volumes. Among the colloids, albumin offers several advantages compared with artificial colloids, including less restrictive dose limitations, lower risk of impaired haemostasis, absence of tissue deposition leading to severe prolonged pruritus, reduced incidence of anaphylactoid reactions, and ease of monitoring to prevent fluid overload. The cost of albumin, nevertheless, limits its usage. Crystalloids currently serve as the first-line fluids in hypovolaemic patients. Colloids can be considered in patients with severe or acute shock or hypovolaemia resulting from sudden plasma loss. Colloids may be combined with crystalloids to obviate administration of large crystalloid volumes. Further clinical trials are needed to define the optimal role for colloids in critically ill patients.

Clinical Trials as Topic↗
PubMed2000

The renal and neurohumoral effects of the addition of low-dose dopamine in septic critically ill patients.

OBJECTIVES: Dopamine exerts a complicated action on the cardiovascular-renal and neurohumoral systems. We evaluated the effects of the addition of different doses of dopamine on top of treatment with norepinephrine on the haemodynamics, renal function and neurohormones of septic shock patients. DESIGN: Open, uncontrolled, dose-finding study. SUBJECTS: Dopamine was administered, after fluid resuscitation, to septic shock patients who were more than 2 h haemodynamically and pulmonary stable with the use of a constant dose norepinephrine. Patients with a serum creatinine above 180 micromol x l were excluded. METHODS: Dopamine doses of 0, 2, 4, 6 and 0 microg x kg(-1) x min(-1) were given consecutively for 1 h each. Neurohormones were measured hourly after baseline levels had been taken. Systemic haemodynamics were measured using a pulmonary artery (PA) catheter every 30 min, whereas urine collections were examined every hour during the study period. RESULTS AND STATISTICAL ANALYSES: Eight patients (mean age 46 +/- 13 years, M/F 3/5) were included. The median norepinephrine dose at the start of the study was 0.29 microg x kg(-1) x min(-1) (range 0.07-0.48 microg x kg(-1) x min(-1)). Cardiac output (CO) rose during the dopamine infusion for all doses from 7.9 +/- 1.74 l/min to a maximum of 10.1 +/- 1.71 l/min, achieved at the 4 microg x kg(-1) x min(-1) dopamine dose, whereas systemic vascular rate (SVR) decreased slightly for all doses. Heart rate remained unchanged during the 2 microg x kg(-1) x min(-1) dose of dopamine but increased for the 4 and 6 microg x kg(-1) x min(-1) doses from 108 +/- 17 to a maximum of 124 +/- 24 beats/min. Filling pressures remained unchanged whereas the mean arterial blood pressure increased (from 83 +/- 7 to 93 +/- 11 mmHg). Plasma renin activity (PRA) was relatively high (but remained unchanged) as were aldosterone levels. Sodium excretion and diuresis increased for all doses, accompanied by an increase of fractional sodium excretion at the 4 and 6 microg x kg(-1) x min(-1) doses of dopamine. Creatinine clearances remained unchanged. All changed values returned to baseline values after cessation of the dopamine administration. CONCLUSION: During norepinephrine infusion, increasing doses of dopamine from 2 to 6 microg x kg(-1) x min(-1) augments CO, diuresis and sodium excretion in patients treated for septic shock, without changes in creatinine clearance. Higher doses of dopamine (4 and 6 microg x kg(-1) x min(-1)) also induce an increase in heart rate. PRA, aldosterone and norepinephrine levels remain unchanged during dopamine infusion.

Cardiotonic Agents↗
PubMed2000

Role of bacterial virulence factors and host factors in the outcome of Escherichia coli bacteraemia.

In a study of the role of virulence factors in the outcome of Escherichia coli bacteraemia, blood isolates from 30 hospitalised patients were characterised with regard to O and K antigens, P and type 1 fimbriae, haemolysin production, cytonecrotising factor 1 production, serum resistance, ability to activate neutrophils and resistance to killing. Patients were analysed to identify host factors contributing to morbidity and mortality. In univariate analyses the presence of a K antigen, type 1 fimbriae, absence of haemolysin production, serum resistance and resistance to killing were associated with morbidity and mortality. In multivariate analyses only the absence of haemolysin production was associated with morbidity and mortality, after taking host factors into account. These preliminary findings suggest that host factors override bacterial virulence factors in determining the course of Escherichia coli bacteraemia. The negative association between haemolysin production and clinical deterioration during Escherichia coli bacteraemia might indicate predominance of less virulent strains in patients with other risk factors for morbidity and mortality or inactivation of neutrophil products needed for host defence.

Aged↗
PubMed2000

Lipopolysaccharide impairs endothelial nitric oxide synthesis in rat renal arteries.

BACKGROUND: Impaired endothelium-dependent vasodilation may contribute to hypoperfusion and failure of abdominal organs, including the kidneys during endotoxin or septic shock. In this study, the short-term (2 h) effects of bacterial lipopolysaccharide (LPS) on endothelium-dependent vasodilation in rat renal and superior mesenteric arteries were documented. METHODS: Rat renal and mesenteric arteries were dissected and exposed in vitro to LPS for two hours. The effects of LPS on vascular reactivity were determined and compared with time-matched controls. Endothelial nitric oxide (NO) release was determined using an NO microsensor in adjacent vessel segments. RESULTS: LPS impaired maximal acetylcholine (ACh)-induced endothelium-dependent vasodilation in renal arteries (62.5 +/- 8.8% vs. 34.4 +/- 7.5% in controls and LPS-exposed arteries), but not in mesenteric arteries. LPS did not alter the sensitivity of renal arteries to exogenous NO. ACh-dependent vasodilation was abolished after blocking NO synthesis with 10-4 mol/L L-NA in control and LPS-incubated renal arteries. When compared with controls, NO release induced by ACh and the receptor-independent calcium ionophore A23187 was significantly decreased (P < 0.05) in LPS-exposed renal segments and was fully abolished in endothelium-denuded segments, indicating that LPS attenuated receptor-dependent as well as receptor-independent endothelial NO release. In contrast, ACh- and A23187-induced NO release was normal in LPS-exposed mesenteric arteries. CONCLUSIONS: These results indicate that LPS-induced selective impairment of ACh-induced endothelium-dependent relaxation in rat renal arteries is caused by decreased endothelial NO release. This may contribute to the propensity for acute renal failure during septic shock.

Animals↗
PubMed2000

Effect of the mechanical ventilatory cycle on thermodilution right ventricular volumes and cardiac output.

The purpose of this study was to evaluate right ventricular (RV) loading and cardiac output changes, by using the thermodilution technique, during the mechanical ventilatory cycle. Fifteen critically ill patients on mechanical ventilation, with 5 cmH(2)O of positive end-expiratory pressure, mean respiratory frequency of 18 breaths/min, and mean tidal volume of 708 ml, were studied with help of a rapid-response thermistor RV ejection fraction pulmonary artery catheter, allowing 5-ml room-temperature 5% isotonic dextrose thermodilution measurements of cardiac index (CI), stroke volume (SV) index, RV ejection fraction (RVEF), RV end-diastolic volume (RVEDV), and RV end-systolic volume (RVESV) indexes at 10% intervals of the mechanical ventilatory cycle. The ventilatory modulation of CI and RV volumes varied from patient to patient, and the interindividual variability was greater for the latter variables. Within patients also, RV volumes were modulated more by the ventilatory cycle than CI and SV index. Around a mean value of 3.95 +/- 1.18 l. min(-1). m(-2) (= 100%), CI varied from 87.3 +/- 5.2 (minimum) to 114.3 +/- 5.1% (maximum), and RVESV index varied between 61.5 +/- 17.8 and 149.3 +/- 34.1% of mean 55.1 +/- 17.9 ml/m(2) during the ventilatory cycle. The variations in the cycle exceeded the measurement error even though the latter was greater for RVEF and volumes than for CI and SV index. For mean values, there was an inspiratory decrease in RVEF and increase in RVESV, whereas a rise in RVEDV largely prevented a fall in SV index. We conclude that cyclic RV afterloading necessitates multiple thermodilution measurements equally spaced in the ventilatory cycle for reliable assessment of RV performance during mechanical ventilation of patients.

Aged↗