The effect of pulsatile cardiopulmonary bypass on lung function in elderly patients.

PURPOSE: Cardiopulmonary bypass is still a major cause of lung injury and delay in pulmonary recovery after cardiac surgery. Although it has been shown that pulsatile flow induced by intra-aortic balloon pumping is beneficial for preserving lung function, it is not clear if the same beneficial effect can be accomplished with pulsatile flow generated in the extracorporeal circuit. Therefore, we investigated the effect of pulsatile flow, produced by a centrifugal pump, on lung function in elderly patients. METHODS: Serial measurements of lung biomarkers Clara cell 16 kD protein, surfactant protein D, and elastase were performed on blood samples from 37 elderly patients (≥75 years) who underwent elective aortic valve replacement surgery with CPB, either with pulsatile perfusion or continuous perfusion. Pulmonary function was assessed by postoperative ventilation time, the arterial blood oxygenation (PaO2/FiO2), the alveolar-arterial oxygen gradient (Aa-O2 gradient) and the pulmonary vascular resistance indexed by body surface area (PVRi). RESULTS: There was no difference in lung function between both groups, as assessed by the postoperative ventilation time, the PaO2/FiO2 ratio, and the Aa-O2 gradient. The PVRi, however, was significantly lower in the pulsatile perfusion group 15 mins after the administration of protamine (p<0.05). The plasma concentrations of the lung biomarkers increased during surgery and peaked at 1 h ICU, there were however no differences between groups. CONCLUSIONS: Pulsatile flow does not seem beneficial to postoperative lung function in elderly patients. Moreover, pulsatile flow does not affect lung function on a subclinical level as assessed by lung biomarkers.

Advanced glycation end-products and skin autofluorescence in end-stage renal disease: a review.

Chronic kidney disease (CKD), especially in its end stage, is marked by extremely high cardiovascular rates of morbidity and mortality; hemodialysis patients have a five-fold shorter life expectancy than healthy subjects of the same age. In CKD the metabolic products that accumulate in the body are so-called uremic toxins. These include advanced glycation end-products (AGE). AGE levels are markedly increased in CKD patients not only because of impaired excretion but also because of increased production. AGE formation has initially been described as a non-enzymatic reaction between proteins and glucose in the so-called Maillard reaction, but they are also more rapidly formed during oxidative stress and subsequent formation of reactive carbonyl compounds like (methyl)glyoxal. AGE accumulate in tissue where they cross-link with proteins, e.g., collagen, inducing tissue stiffening of blood vessels and skin. They may also interact with receptor of AGE (RAGE) and other receptors, which lead to activation of intracellular transduction mechanisms resulting in cytokine release and further tissue damage in CKD. The accumulation of AGE in the skin can be measured non-invasively using autofluorescence. The skin autofluorescence is a strong marker of cardiovascular mortality in CKD. The focus of this review is on the role of tissue and plasma AGE, and of skin autofluorescence as a proxy of tissue AGE accumulation, in the increase in cardiovascular disease in end stage renal disease (ESRD). This review will also present the possibility of reducing the AGE accumulation in ESRD patients using the following five methods: 1) use of low AGE peritoneal dialysis solutions; 2) use of advanced hemodialysis techniques; 3) use of AGE reducing drugs; 4) optimizing the nutrition of hemodialysis patients; and 5) renal transplantation.

Skin and plasma autofluorescence during hemodialysis: a pilot study.

Skin autofluorescence (AF) is related to the accumulation of advanced glycation end products (AGEs) and is one of the strongest prognostic markers of mortality in hemodialysis (HD) patients. The aim of this pilot study was to investigate whether changes in skin AF appear after a single HD session and if they might be related to changes in plasma AF. Skin and plasma AF were measured before and after HD in 35 patients on maintenance HD therapy (nine women and 26 men, median age 68 years, range 33-83). Median dialysis time was 4 h (range 3-5.5). Skin AF was measured noninvasively with an AGE Reader, and plasma AF was measured before and after HD at 460 nm after excitation at 370 nm. The HD patients had on average a 65% higher skin AF value than age-matched healthy persons (P < 0.001). Plasma AF was reduced by 14% (P < 0.001), whereas skin AF was not changed after a single HD treatment. No significant influence of the reduced plasma AF on skin AF levels was found. This suggests that the measurement of skin AF can be performed during the whole dialysis period and is not directly influenced by the changes in plasma AF during HD.

Increase in skin autofluorescence and release of heart-type fatty acid binding protein in plasma predicts mortality of hemodialysis patients.

Advanced glycation end-products (AGEs) are uremic toxins that accumulate progressively in hemodialysis (HD) patients. The aim of this study was to assess the 1-year increase in skin autofluorescence (ΔAF), a measure of AGEs accumulation and plasma markers, as predictors of mortality in HD patients. One hundred sixty-nine HD patients were enrolled in this study. Skin autofluorescence was measured twice, 1 year apart using an AGE Reader (DiagnOptics Technologies BV, Groningen, The Netherlands). Besides routine blood chemistry, additional plasma markers including superoxide dismutase, myeloperoxydase, intercellular adhesion molecule 1 (ICAM-1), C-reactive protein (hs-CRP), heart-type fatty acid binding protein (H-FABP), and von Willebrand factor were measured at baseline. The mortality of HD patients was followed for 36 months. Skin autofluorescence values of the HD patients at the two time points were significantly higher (P < 0.001) than those of healthy subjects of the same age. Mean 1-year ΔAF of HD patients was 0.16 ± 0.06, which was around seven- to ninefold higher than 1-year ΔAF in healthy subjects. Multivariate Cox regression showed that age, hypertension, 1-year ΔAF, hs-CRP, ICAM-1, and H-FABP were independent predictors of overall mortality. Hypertension, 1-year ΔAF, hs-CRP, and H-FABP were also independent predictors of cardiovascular mortality. One-year ΔAF and plasma H-FABP, used separately and in combination, are strong predictors of overall and cardiovascular mortality in HD patients.

Flush at room temperature followed by storage on ice creates the best lung graft preservation in rats.

Current clinical lung preservation techniques have not eliminated ischaemia-reperfusion (I/R) injury, despite many improvements. The optimal combination of flush and storage temperatures remain unclear in lung preservation. This is the first study to investigate a range of temperatures with 24-h inflated storage using consistent state-of-the-art preservation techniques. A rat lung transplant model was used to investigate the optimal combination of flush and storage temperatures. In six groups, rat lungs were flushed at 4 °C, 10 °C or room temperature (F(4) /F(10) /F(Rt)) with Perfadex and stored inflated for 24 h in Perfadex on melting ice or at 10 °C (S(ice) /S(10)). Left donor lungs were transplanted for analysis. During 2-h reperfusion, the lung graft function was measured (blood gases, maximum ventilation pressure and static compliance) and lung graft injury was also assessed (W/D ratio, total lung protein, Tryptase, Myeloperoxidase). Right donor lungs were assessed for W/D ratio only after flush and storage. For baseline measurements, left lungs without intervention were used. The combination of F(Rt) -S(ice) showed a significantly higher pO(2), lower P(max), low W/D ratios and total protein levels of left lungs after reperfusion when compared with F(4) -S(ice) and baseline. Storage at 10 °C did not improve preservation. We conclude that F(Rt) -S(ice) creates the best lung graft preservation.

In situ lung perfusion is a valuable tool to assess lungs from donation after circulatory death donors category I-II.

Donations after circulatory death (DCD) lung grafts are an alternative to extend the donor pool in lung transplantation. This study investigates the use of an in situ lung perfusion system (ISLP) in the donor to evaluate category I-II lungs. Pigs were sacrificed by ventricular fibrillation. All animals underwent 20 min of cardiopulmonary resuscitation and 5 min hands-off period after which heparin was administered. In group [WI-1], this was followed by 1 h of warm ischemia (WI) and 2 h of topical cooling (TC). In group [WI-2], 2 h of WI was followed by 1 h of TC. In group [WI-0], there was a minimal period of WI and no TC. In all three groups, the lungs were then evaluated during 60 min with ISLP. [WI-0] lungs showed a significantly higher compliance and Δ PO2 /FiO2 compared with [WI-1] and [WI-2]. PaCO2 and lactate production were higher in [WI-2] versus [WI-0]. Wet/Dry weight ratio was significantly higher in [WI-2] compared with [WI-0] in two lung biopsy locations. A high W/D weight ratio was correlated with a lower compliance, higher lactate production, and a higher PaCO2 . ISLP is an effective way to assess the quality of lungs from category I-II DCD donors.

The utility of lung epithelium specific biomarkers in cardiac surgery: a comparison of biomarker profiles in on- and off-pump coronary bypass surgery.

BACKGROUND: Despite continuous improvements in materials and perfusion techniques, cardiac surgery still causes lung injury and a delay of pulmonary recovery. Currently, there is no gold standard for quantifying cardiac surgery induced lung injury and dysfunction. Adding objective measures, such as plasma biomarkers, could be of great use here. In this study the utility of lung epithelium specific proteins as biomarkers for lung dysfunction was evaluated. METHODS: Serial measurements of plasma concentrations of Clara cell 16 kD (CC16) protein, Surfactant protein D (SP-D), Elastase and Myeloperoxidase were performed on blood samples from 40 patients who underwent coronary artery bypass grafting with cardiopulmonary bypass (CABG, n = 20) or without cardiopulmonary bypass (OPCAB, n = 20). RESULTS: The increase of SP-D and CC16 between pre-operative concentrations and concentrations at the end of cardiopulmonary bypass, correlated with the Aa-O2 gradient at 1 hour on the ICU (Rs = 0.409, p = .016 and Rs = 0.343, p = .043, respectively).Furthermore, SP-D and CC16 were higher in CABG than in OPCAB at the end of surgery [8.96 vs. 4.91 ng/mL, p = .042 and 92 vs. 113%, p = .007, respectively]. After 24 h both biomarkers returned to their baseline values. CONCLUSIONS: Our results show that increases in plasma of SP-D and CC16 correlate with clinical lung injury after coronary artery bypass surgery. Therefore, lung epithelium specific proteins seem to be a useful biomarker for measuring lung injury in the setting of cardiac surgery.

Use of hydroxyethyl starch for inducing red blood cell aggregation.

UNLABELLED: Aggregation of human red blood cells (RBC) remains of biological and clinical interest. Replacement of plasma proteins by polymers to induce RBC aggregation may help to unravel the fundamentals of the aggregation process. Two theories exist to explain RBC aggregation mechanisms: a depletion and a bridging theory. RBC aggregation induced by hydroxyethyl starch (HES) increases with polymer size, which suggests that aggregation is induced via the bridging theory. In this study, the electrophoretic mobility (EPM) was measured to investigate RBC aggregation induced by 200 kDa HES polymers. Also, we evaluated if these polymers were useful for demonstrating aggregation differences between RBCs from healthy and type-1 diabetes mellitus (T1DM) subjects. Our results demonstrate that EPM values of RBCs in 200 kDa HES solutions were less negative than could be predicted by the viscosity of the suspension, supporting the bridging theory. Furthermore, aggregation analysis using the LORCA demonstrated that 200 kDa HES solution enhanced RBC aggregation of healthy and diabetic subjects similarly as standard 500 kDa dextran solutions. IN CONCLUSION: our data supports the bridging mechanism underlying 200 kDa HES induced RBC aggregation. In addition, both polymers are useful for demonstrating cellular induced aggregation differences between RBCs from healthy and T1DM subjects.

PUCA pump and IABP comparison: analysis of hemodynamic and energetic effects using a digital computer model of the circulation.

The pulsatile catheter pump (PUCA pump) is a left ventricular assist device that provides additional flow to the left ventricle. It is usually run in order to ensure a counterpulsation effect, as in the case of the intra-aortic balloon pump (IABP). Because of this similarity, a comparison between the PUCA pump and the IABP was conducted from both the hemodynamic and energetic points of view. Numerical models of the two devices were created and connected to the CARDIOSIM cardiovascular simulator. The PUCA and IABP models were then verified using in vivo experimental data and literature data, respectively. Numerical experiments were conducted for different values of left ventricular end systolic elastance (Els) and systemic arterial compliance (Csa). The energetic comparison was conducted taking into account the diastolic pressure time index and the endocardial viability ratio. Hemodynamic results expressed as cardiac output (CO) and mean coronary blood flow (CBF) show that both the IABP and the PUCA pump efficacy decrease with higher values of Els and Csa. The IABP especially shows higher sensitivity to these parameters, to the extent that in some cases CO actually drops and CBF does not increase. On the other hand, for lower values of Csa, IABP performance improves so much that the PUCA pump flow needs to be increased in order to ensure a hemodynamic effect comparable to that of the IABP. Energetic results show a trend similar to the hemodynamic ones. The study will be continued by investigating other energetic variables and the autonomic response of the cardiovascular system.

Clinical effectiveness of centrifugal pump to produce pulsatile flow during cardiopulmonary bypass in patients undergoing cardiac surgery.

Although the centrifugal pump has been widely used as a nonpulsatile pump for cardiopulmonary bypass (CPB), little is known about its performance as a pulsatile pump for CPB, especially on its efficacy in producing hemodynamic energy and its clinical effectiveness. We performed a study to evaluate whether the Rotaflow centrifugal pump produces effective pulsatile flow during CPB and whether the pulsatile flow in this setting is clinically effective in adult patients undergoing cardiac surgery. Thirty-two patients undergoing CPB for elective coronary artery bypass grafting were randomly allocated to a pulsatile perfusion group (n = 16) or a nonpulsatile perfusion group (n = 16). All patients were perfused with the Rotaflow centrifugal pump. In the pulsatile group, the centrifugal pump was adjusted to the pulsatile mode (60 cycles/min) during aortic cross-clamping, whereas in the nonpulsatile group, the pump was kept in its nonpulsatile mode during the same period of time. Compared with the nonpulsatile group, the pulsatile group had a higher pulse pressure (P < 0.01) and a fraction higher energy equivalent pressure (EEP, P = 0.058). The net gain of pulsatile flow, represented by the surplus hemodynamic energy (SHE), was found much higher in the CPB circuit than in patients (P < 0.01). Clinically, there was no difference between the pulsatile and nonpulsatile groups with regard to postoperative acute kidney injury, endothelial activation, or inflammatory response. Postoperative organ function and the duration of hospital stay were similar in the two patient groups. In conclusion, pulsatile CPB with the Rotaflow centrifugal pump is associated with a small gain of EEP and SHE, which does not seem to be clinically effective in adult cardiac surgical patients.

Skin autofluorescence as marker of tissue advanced glycation end-products accumulation in formerly preeclamptic women.

CONDENSATION: In women with a history of preeclampsia skin autofluorescence as marker of tissue AGEs accumulation is increased, supporting a common causal metabolic or vascular link between preeclampsia and cardiovascular diseases. OBJECTIVE: To investigate whether skin autofluorescence (AF), as marker of tissue accumulation of advanced glycation end-products (AGEs), is elevated in women with a 4-year history of severe preeclampsia. METHODS: About 17 formerly preeclamptic women and 16 controls were included. Skin AF and several traditional cardiovascular risk factors were recorded. RESULTS: In comparison to controls, formerly preeclamptic women had higher skin AF of the legs, body mass index (BMI), blood pressure, and high-sensitivity C-reactive protein (hsCRP), HbA1C, and triglycerides in serum. CONCLUSION: Skin AF as well as cardiovascular risk factors is elevated in formerly preeclamptic women. These results suggest a common causal vascular link between preeclampsia and cardiovascular diseases.

The value of machine perfusion perfusate biomarkers for predicting kidney transplant outcome.

BACKGROUND: Retrospective evidence suggests that lactate dehydrogenase, aspartate aminotransferase, total glutathione-S-transferase (GST), alanine-aminopeptidase, N-acetyl-ß-D-glucosaminidase (NAG), and heart-type fatty acid binding protein (H-FABP) measured during kidney machine perfusion (MP) could have predictive value for posttransplant outcome. However, these data may be biased due to organ discard based on biomarker measurements, and previous analyses were not adjusted for likely confounding factors. No reliable prospective evidence has been available so far. Nevertheless, some centers already use these biomarkers to aid decisions on accepting or discarding a donor kidney. METHODS: From 306 deceased-donor kidneys donated after brain death or controlled cardiac death and included in an international randomized controlled trial, these six biomarkers were measured in the MP perfusate. In this unselected prospective data set, we tested whether concentrations were associated with delayed graft function, primary nonfunction, and graft survival. Multivariate regression models investigated whether the biomarkers remained independent predictors when adjusted for relevant confounding factors. RESULTS: GST, NAG, and H-FABP were independent predictors of delayed graft function but not of primary nonfunction and graft survival. Lactate dehydrogenase, aspartate aminotransferase, and alanine-aminopeptidase had no independent prognostic potential for any of the endpoints. Perfusate biomarker concentrations had no relevant correlation with cold ischemic time or renal vascular resistance on the pump. CONCLUSIONS: Increased GST, NAG, or H-FABP concentrations during MP are an indication to adjust posttransplant recipient management. However, this study shows for the first time that perfusate biomarker measurements should not lead to kidney discard.

Skin color independent assessment of aging using skin autofluorescence.

Skin autofluorescence (AF) for the non-invasive assessment of the amount of accumulated tissue Advanced Glycation Endproducts (AGEs) increases with aging. In subjects with darker skin colors, measurements typically result in lower AF values than in subjects with fair skin colors, e.g. due to selective absorption by skin compounds. Our aim was to provide a new method for calculating skin AF, yielding values that are independent of skin color. The deviation of skin AF of healthy subjects with various darker skin types (N = 99) compared to reference values from Caucasians showed to be a function of various parameters that were derived from reflectance and emission spectra in the UV and visible range (adjusted R(2) = 80%). Validation of the new algorithm, based on these findings, in a separate dataset (N = 141) showed that results of skin AF can now be obtained to assess skin AGEs independently of skin color.

The effects of cryopreservation on red blood cell rheologic properties.

BACKGROUND: In transfusion medicine, frozen red blood cells (RBCs) are an alternative for liquid-stored RBCs. Little is known about the rheologic properties (i.e., aggregability and deformability) of thawed RBCs. In this study the rheologic properties of high-glycerol frozen RBCs and postthaw stored in saline-adenine-glucose-mannitol medium were compared to those of conventionally liquid-stored and fresh RBCs. STUDY DESIGN AND METHODS: Fresh RBCs were obtained from healthy volunteers. Leukoreduced liquid-stored and thawed deglycerolized RBC units were obtained from the Sanquin Blood Bank. RBCs were tested for aggregability (aggregation index [AI]), deformability (elongation index [EI]), and various hematologic variables. RESULTS: The AI of thawed RBCs was reduced, compared to fresh and liquid-stored RBCs (p<0.05). The EI of stored RBCs was significantly enhanced over a shear stress range of 2.0 to 50Pa compared to fresh RBCs (p<0.05). No significant differences in EI between thawed and 21- or 35-day liquid-stored RBCs were observed. The osmotic fragility, hemolysis, mean cell volume, and mean cell hemoglobin concentration of thawed RBCs were markedly altered, compared to fresh and liquid-stored RBCs (p< 0.05). The adenosine triphosphate (ATP) content of thawed RBCs was similar to 3- or 21-day liquid-stored and fresh RBCs. CONCLUSIONS: Thawed RBCs are more fragile than conventionally liquid-stored and fresh RBC. The freeze-thaw-wash process, however, did not adversely affect the aggregability and deformability or the ATP content of thawed RBCs. Based on the rheologic properties, cryopreserved RBCs are a valuable alternative to liquid-stored RBCs.

Is red blood cell rheology preserved during routine blood bank storage?

BACKGROUND: Red blood cell (RBC) units stored for more than 2 weeks at 4 degrees C are currently considered of impaired quality. This opinion has primarily been based on altered RBC rheologic properties (i.e., enhanced aggregability, reduced deformability, and elevated endothelial cell interaction), during prolonged storage of nonleukoreduced RBC units. In this study, the rheologic properties and cell variables of leukoreduced RBC units, during routine blood bank storage in saline-adenine-glucose-mannitol, were investigated. STUDY DESIGN AND METHODS: Ten leukoreduced RBC units were stored at the blood bank for 7 weeks at 4 degrees C. RBCs were tested weekly for aggregability, deformability, and other relevant variables. RESULTS: RBC aggregability was significantly reduced after the first week of storage but recovered during the following weeks. After 7 weeks aggregability was slightly, but significantly, reduced (46.9 + or - 2.4-44.3 + or - 2.2 aggregation index). During storage the osmotic fragility was not significantly enhanced (0.47 + or - 0.01% phosphate-buffered saline) and the deformability at shear stress of 3.9 Pa was not significantly reduced (0.36 + or - 0.01 elongation index [EI]). The deformability at 50 Pa was reduced (0.58 + or - 0.01-0.54 + or - 0.01 EI) but remained within reference values (0.53 + or - 0.04). During 5 weeks of storage, adenosine triphosphate was reduced by 54% whereas mean cell volume, pH, and mean cell hemoglobin concentration were minimally affected. CONCLUSIONS: RBC biochemical and physical alterations during storage minimally affected the RBC ability to aggregate and deform, even after prolonged storage. The rheologic properties of leukoreduced RBC units were well preserved during 7 weeks of routine blood bank storage.

Spatiotemporal progression of localized bacterial peritonitis before and after open abdomen lavage monitored by in vivo bioluminescent imaging.

BACKGROUND: Bacterial peritonitis is a life-threatening abdominal infection associated with high morbidity and mortality. The rat is a popular animal model for studying peritonitis and its treatment, but longitudinal monitoring of the progression of peritonitis in live animals has been impossible until now and thus required a large number of animals. Our objective was to develop a noninvasive in vivo imaging technique to monitor the spatiotemporal spread of bacterial peritonitis. METHODS: Peritonitis was induced in 8 immunocompetent male Wistar rats by placing fibrin clots containing 5x10(8) cells of both Bacteroides fragilis (American Type Tissue Culture [ATCC)] 25,285 and bioluminescent Escherichia coli Xen14. After 1 or 2 days, infected clots were removed and open abdomen lavage was performed. In vivo bioluminescent imaging was used to monitor the spread of peritonitis. RESULTS: Bioluminescent in vivo imaging showed an increase in the area of spread, and the number of E. coli tripled into the rat's abdominal cavity on day 1 after clot insertion; however, on day 2, encapsulation of the clot confined bacterial spread. Bioluminescent E. coli respread over the peritoneal cavity after lavage; within 10 days, however, in vivo imaging showed a decrease of 3-4 orders of magnitude in bacterial load. CONCLUSION: Bioluminescent in vivo imaging can be effectively used to monitor the spatiotemporal behavior of the peritonitis during 3 different stages of the disease process: initiation, treatment, and follow-up. Imaging allows researchers to repeatedly image the same animal, thereby reducing variability and providing greater confidence in determining treatment efficacies for therapeutic interventions using a small number of animals.

Does hepatitis C increase the accumulation of advanced glycation end products in haemodialysis patients?

BACKGROUND: Hepatitis C may cause increased levels of oxidative stress that contribute to accumulation of advanced glycation end products (AGEs), which increase the risk of cardiovascular disease (CVD). The aim of this study was to determine the influence of hepatitis C on AGE accumulation in haemodialysis patients. METHODS: AGE accumulation was measured by means of skin autofluorescence (AF) in 92 haemodialysis (HD) patients and 93 age-matched healthy controls. In the HD patients, CVD-related biochemical variables were also measured. The HD patients were tested for hepatitis C virus (HCV) antibodies and allocated to a HCV+ or HCV- group. RESULTS: Skin AF of the healthy subjects was lower than skin AF in the HD patients (3.13 +/- 0.95 vs 2.2 +/- 0.47; P < 0.001). We calculated the average increase of skin AF in the healthy subjects to be 0.017 arbitrary units per year, being 14 times lower than in HD patients with CVD only and 20 times lower than in HD patients suffering from combined CVD and diabetes mellitus (DM). Multivariate regression analysis showed that AGE accumulation in HD patients can be described by the independent effects of age, DM, CVD and HD vintage. Although inter-cellular adhesion molecule 1 and liver enzymes were elevated in HCV+ HD patients, levels of oxidative stress markers and skin AF were not significantly different between HCV+ and HCV- HD patients. CONCLUSIONS: AGE accumulation was higher in the HD patients than in the healthy controls. AGE accumulation did not differ in HCV+ and HCV- HD patients. This might be due to the fact that hepatitis C did not cause oxidative stress in our HD population. Independent markers of AGE accumulation were age, HD vintage, DM and CVD, but not hepatitis C.