The short-term effects of RBC transfusions on intestinal injury in preterm infants.

BACKGROUND: Anemic preterm infants may require red blood cell (RBC) transfusions to maintain sufficient oxygen supply to vital organs. Transfusion treatment, however, may have adverse intestinal effects. We aimed to investigate the short-term effects of RBC transfusions, hypothesizing to find signs of oxidative stress and intestinal injury, possibly related to levels of splanchnic (re-)oxygenation. METHODS: We prospectively included preterm infants (gestational age < 32 weeks). We measured urinary biomarkers for oxidative stress (8-isoprostane) and intestinal cell injury (intestinal fatty acid-binding protein, I-FABP) shortly before and after RBC transfusion. Splanchnic oxygen saturation (rsSO2) and rsSO2 variability were assessed simultaneously. RESULTS: Twenty-nine preterm infants received 58 RBC transfusions at various postnatal ages. Six of them developed necrotizing enterocolitis (NEC) after transfusion. Urinary 8-isoprostane and I-FABP increased following RBC transfusion (median 282-606 pg/ml and 4732-6968 pg/ml, p < 0.01), more pronounced in infants who developed NEC. Change in I-FABP correlated with change in 8-isoprostane (rho = 0.623, p < 0.01). Lower rsSO2 variability, but not higher mean rsSO2 was associated with higher 8-isoprostane and I-FABP levels after transfusion. CONCLUSIONS: Preterm RBC transfusions are associated with concomitant signs of oxidative stress and intestinal injury, parallel with lower variability in splanchnic oxygenation. This may represent the early pathogenetic process of transfusion-associated NEC. IMPACT: Red blood cell (RBC) transfusions in preterm infants are associated with a near 2-fold increase in urinary biomarkers for oxidative stress (8-isoprostane) and intestinal cell injury (intestinal fatty acid-binding protein, I-FABP). Magnitude of change in I-FABP strongly correlated with the magnitude of 8-isoprostane change, suggesting a role for oxidative stress in the pathogenesis of intestinal injury. Lower splanchnic oxygen saturation variability following RBC transfusion was associated with higher 8-isoprostane and I-FABP levels. Loss of splanchnic variability after RBC transfusion may result from increased oxidative stress and its concomitant intestinal injury, possibly representing the early pathogenetic process of transfusion-associated necrotizing enterocolitis.

Neonatal anemia relates to intestinal injury in preterm infants.

BACKGROUND: Anemia is associated with decreased tissue oxygenation in preterm infants and may contribute to developing necrotizing enterocolitis (NEC). We aimed to investigate whether hemoglobin level is associated with intestinal injury, by comparing anemic infants 10 days prior to red blood cell (RBC) transfusion with non-anemic controls. METHODS: A nested case-control study in which we matched anemic preterms (gestational age (GA) < 32 weeks) with non-anemic controls (1:1), based on GA, birth weight (BW), and postnatal age. We measured urinary intestinal fatty acid-binding protein, I-FABP, marker for intestinal injury, twice weekly. Simultaneously, we assessed splanchnic oxygen saturation (rsSO2) and rsSO2 variability. RESULTS: Thirty-six cases and 36 controls were included (median GA 27.6 weeks, BW 1020 grams). Median I-FABP level was higher in cases from 6 days to 24-h before transfusion (median ranging: 4749-8064 pg/ml versus 2194-3751 pg/ml). RsSO2 and rsSO2 variability were lower in cases than controls shortly before transfusion. Hemoglobin levels correlated negatively with rsSO2 and rsSO2 variability in cases, and negatively with I-FABP in cases and controls together. CONCLUSIONS: Urinary I-FABP levels were higher in anemic infants before RBC transfusion than in non-anemic matched controls, suggesting intestinal injury associated with anemia. This may predispose to NEC in some anemic preterm infants. IMPACT: Anemia is a common comorbidity in preterm infants and may lead to impaired splanchnic oxygen saturation and intestinal tissue hypoxia, a proposed mechanism for NEC. Lower hemoglobin level is associated with higher urinary I-FABP levels, a marker for intestinal injury, both in anemic preterm infants and in cases and controls together. Lower splanchnic oxygen saturation and reduction of its variability are associated with higher urinary I-FABP levels in anemic preterm infants before their first RBC transfusion. These results support the hypothesis that anemia in very preterm infants results in intestinal cell injury, which may precede NEC development in some.

Does Intraoperative Cell Salvage Reduce Postoperative Infection Rates in Cardiac Surgery?

OBJECTIVE: Primary outcome was the risk for infections after cell salvage in cardiac surgery. DESIGN: Data of a randomized controlled trial on cell salvage and filter use (ISRCTN58333401). SETTING: Six cardiac surgery centers in the Netherlands. PARTICIPANTS: All 716 patients undergoing elective coronary artery bypass grafting, valve surgery, or combined procedures over a 4-year period who completed the trial. INTERVENTIONS: Postoperative infection data were assessed according to Centre of Disease Control and Prevention/National Healthcare Safety Network surveillance definitions. MEASUREMENTS AND MAIN RESULTS: Fifty-eight (15.9%) patients with cell salvage had infections, compared with 46 (13.1%) control patients. Mediation analysis was performed to estimate the direct effect of cell salvage on infections (OR 2.291 [1.177;4.460], p = 0.015) and the indirect effects of allogeneic transfusion and processed cell salvage blood on infections. Correction for confounders, including age, seks and body mass index was performed. Allogeneic transfusion had a direct effect on infections (OR = 2.082 [1.133;3.828], p = 0.018), but processed cell salvage blood did not (OR = 0.999 [0.999; 1.001], p = 0.089). There was a positive direct effect of cell salvage on allogeneic transfusion (OR = 0.275 [0.176;0.432], p < 0.001), but a negative direct effect of processed cell salvage blood (1.001 [1.001;1.002], p < 0.001) on allogeneic transfusion. Finally, there was a positive direct effect of cell salvage on the amount of processed blood. CONCLUSIONS: Cell salvage was directly associated with higher infection rates, but this direct effect was almost completely eliminated by its indirect protective effect through reduced allogeneic blood transfusion.

Additional filtering of blood from a cell salvage device is not likely to show important additional benefits in outcome in cardiac surgery.

BACKGROUND: Several authors and manufacturers of cell salvage devices recommend additional filtering of processed blood before transfusion. There is no evidence to support this practice. Therefore, we compared the clinical outcome and biochemical effects of cell salvage with or without additional filtering. STUDY DESIGN AND METHODS: The patients, scheduled for coronary artery bypass grafting, valve replacement, or combined procedures were part of our randomized multicenter factorial study of cell salvage and filter use on transfusion requirements (ISRCTN 58333401). They were randomized to intraoperative cell salvage or cell salvage plus additional WBC depletion filter. We compared the occurrence of major adverse events (combined death/stroke/myocardial infarction) as primary outcome and minor adverse events (renal function disturbances, infections, delirium), ventilation time, and length of stay in the intensive care unit and hospital. We also measured biochemical markers of organ injury and inflammation. RESULTS: One hundred eighty-nine patients had cell salvage, and 175 patients had cell salvage plus filter and completed the study. Demographic data, surgical procedures, and amount of salvaged blood were not different between the groups. There was no difference in the primary outcome with a risk of 6.3% (95% confidence interval [CI], 3.34-11.25) in the cell salvage plus filter group versus 5.8% (95% CI, 3.09-10.45) in the cell salvage group, a relative risk of 1.08 (95% CI, 0.48- 2.43]. There were no differences in minor adverse events and biochemical markers between the groups. CONCLUSION: The routine use of an additional filter for transfusion of salvaged blood is unlikely to show important additional benefits.

Short-term Effects of Tolvaptan in Individuals With Autosomal Dominant Polycystic Kidney Disease at Various Levels of Kidney Function.

BACKGROUND: A recent study showed that tolvaptan, a vasopressin V2 receptor antagonist, decreased total kidney volume (TKV) growth and estimated glomerular filtration rate (GFR) loss in autosomal dominant polycystic kidney disease (ADPKD) with creatinine clearance≥60mL/min. The aim of our study was to determine whether the renal hemodynamic effects and pharmacodynamic efficacy of tolvaptan in ADPKD are dependent on GFR. STUDY DESIGN: Clinical trial with comparisons before and after treatment. SETTING & PARTICIPANTS: Patients with ADPKD with a wide range of measured GFRs (mGFRs; 18-148 mL/min) in a hospital setting. INTERVENTION: Participants were studied at baseline and after 3 weeks of treatment with tolvaptan given in increasing dosages, if tolerated (doses of 60, 90, and 120mg/d in weeks 1, 2, and 3, respectively). OUTCOMES: Change in markers for aquaresis (free-water clearance, urine and plasma osmolality, 24-hour urine volume, and plasma copeptin) and kidney injury (TKV and kidney injury biomarkers). MEASUREMENTS: GFR was measured by (125)I-iothalamate clearance; TKV, by magnetic resonance imaging; biomarker excretion, by enzyme-linked immunosorbent assay; and osmolality, by freezing point depression. RESULTS: In 27 participants (52% men; aged 46±10 years; mGFR, 69±39mL/min; TKV, 2.15 [IQR, 1.10-2.77] L), treatment with tolvaptan led to an increase in urine volume and free-water clearance and a decrease in urine osmolality, TKV, and kidney injury marker excretion. Changes in urine volume and osmolality with treatment were less in participants with lower baseline mGFRs (both P<0.01). However, change in fractional free-water clearance was greater at lower baseline mGFRs (P=0.001), suggesting that participants with decreased GFRs responded more to tolvaptan per functioning nephron. LIMITATIONS: Limited sample size, no control group. CONCLUSIONS: In patients with ADPKD with decreased kidney function, response to tolvaptan is lower for TKV, urinary volume, and osmolality, but larger for fractional free-water clearance. This latter finding suggests that patients with ADPKD with lower GFRs might benefit from long-term treatment with tolvaptan, as has been observed for patients with preserved GFRs.

Effect of minimized perfusion circuit on brain injury markers carnosinase and brain-type fatty binding protein in coronary artery bypass grafting patients.

A minimized perfusion circuit (MPC) has proven to be superior to the conventional circulatory perfusion bypass (CCPB) as it reduces the blood-material interaction and hemodilution. Until now not much is known about impact these different perfusion systems have on the brain. The objective of this study is to determine carnosinase and brain-type fatty binding protein (BFABP) activity as novel specific biomarkers for ischemic brain tissue damage and how their activity differs during and after MPC and CCPB as well as to compare the inflammatory response of both perfusion systems. In a prospective pilot study, 28 patients undergoing coronary artery bypass grafting were randomly divided into an MPC group (n = 14) and a CCPB group (n = 14). Blood samples were taken before, during, and after operation until the fifth postoperative day. The brain biomarker carnosinase was determined by measuring the rate of histidine production from the substrate homocarnosine, whereas BFABP and interleukin-6 were determined by enzyme-linked immunosorbent assay (ELISA). C-reactive protein (CRP) and endothelin-1 were determined by enzyme immunoassay. The mean serum carnosinase activity was significantly higher in MPC (0.57 ± 0.34 nM histidine/mL/min) as compared with the CCPB group (0.36 ± 0.13 nM histidine/mL/min) at the end of operation (P = 0.02). The BFABP did not show any difference between the two groups in the immediate postoperative period until the second postoperative day. From that time point onward, it showed a steep increase in the CCPB group (581.3 ± 157.11 pg/mL) as compared with the concentrations in the MPC group (384.6 ± 39 pg/mL) (P = 0.04). The inflammation markers interleukin-6 and CRP showed a similar pattern in both groups without significant difference. In contrast, the leukocyte count on operation day and endothelin-1 on the first postoperative day were significantly higher in the CCPB group (P = 0.01, P = 0.03, respectively). MPC showed a significant higher and stable serum carnosinase activity during extracorporeal circulation as compared with the CCPB due to less hemodilution and a better preserved oxygen capacity. As a consequence, the antioxidant stress during MPC is limited as compared with CCPB, which means less brain tissue damage reflected by a lower BFABP release. Except endothelin-1 and leukocyte count, the inflammatory response of the MPC and CCPB was equal.

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.

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.

Development of an in vitro system and model-based translational framework to assess haemolysis risk following intravenous abuse of medications containing polyethylene oxide.

Multiple cases of potentially life-threatening thrombotic microangiopathy (TMA) have resulted from intravenous abuse of medications containing polyethylene oxide (PEO), most often Opana ER (oxymorphone hydrochloride extended release). No validated models are available to assess the risk of TMA with different formulations and extraction methods following intravenous abuse. We have developed an in vitro system that involves passing pooled blood containing the excipient of interest through a syringe needle and assessing haemolysis via haemoglobin release. Haemolysis is induced by high shear stress caused by the flow of blood containing PEO through a narrow-bore syringe needle, recapitulating the mechanism in small blood vessels. Using the in vitro system, we demonstrate that high-molecular-weight PEO (>1 MDa) induces haemolysis in a concentration-dependent manner under flowing but not static conditions. We use data from the in vitro system and published in vivo data to predict the time course of the haemolytic response in vivo via a pharmacometric model. The in vitro system is a novel method for investigating factors influencing PEO-induced haemolysis. In combination with our model-based translational framework, the in vitro system allows straightforward assessment of the haemolytic potential of PEO-containing medications, and may find application in gauging TMA risk following intravenous abuse.

The association of hemodilution and transfusion of red blood cells with biochemical markers of splanchnic and renal injury during cardiopulmonary bypass.

BACKGROUND: Hemodilution is the main cause of a low hematocrit concentration during cardiopulmonary bypass. This low hematocrit may be insufficient for optimal tissue oxygen delivery and often results in packed cell transfusion. Our objective in this study was to find a relationship between intraoperative hematocrit and allogeneic blood transfusion on release of postoperative injury markers from the kidneys and the splanchnic area. METHODS: Fifty consecutive patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were included. Systemic tissue hypoxia was assessed by lactate concentrations. Kidney and splanchnic ischemia were assessed by the measurement of N-acetyl-beta-D-glucosaminidase (NAG) and intestinal fatty acid binding protein (IFABP) in urine. Patients were retrospectively placed into groups according to their lowest hematocrit concentration on bypass (<24% or >or=24%). RESULTS: The intraoperative lactate and the postoperative NAG and IFABP concentrations were higher in the low hematocrit group (<24%) than in the high hematocrit group (>or=24%; P < 0.05). Low hematocrit correlated with higher lactate concentrations (R(2) = 0.150, P < 0.01) and with higher NAG concentrations (R(2) = 0.138, P < 0.01) and IFABP concentrations (R(2) = 0.107, P < 0.01) postoperatively. Transfusion of packed cells during cardiopulmonary bypass correlated with higher lactate (R(2) = 0.089, P < 0.05), NAG (R(2) = 0.431, P < 0.01), and IFABP concentrations (R(2) = 0.189, P < 0.01). CONCLUSIONS: The results support the concept that hemodilution below an intraoperative hematocrit of 24% and consequently transfusion of red blood cells is related to release of injury markers of the kidneys and splanchnic area.

The optimal incubation time for in vitro hemocompatibility testing: Assessment using polymer reference materials under pulsatile flow with physiological wall shear stress conditions.

During hemocompatibility testing, activation products may reach plateau values which can result in less distinction between hemocompatible and hemo-incompatible materials. Of concern is an underestimation of the blood activation caused by the biomaterial of interest, which may result in a false assessment of hemocompatibility. To elucidate the optimal incubation time for in vitro hemocompatibility testing, we used the Haemobile circulation model with human whole blood. Blood from healthy volunteers was in vitro incubated under pulsatile flow with physiological wall shear stress conditions at 37°C for 30, 60, 120, or 240 min. Test loops containing low-density polyethylene and polydimethylsiloxane served as low and high reference materials, that is, hemocompatible and hemo-incompatible biomaterials, respectively. In addition, empty loops served as a negative reference. Thrombogenicity, platelet function, inflammatory response, coagulation, and hemolysis between references and incubation times were compared. We found that thrombogenicity and platelet function were significantly affected by both the duration of incubation and the type of material. In particular, thrombogenicity and platelet function assessments were affected by incubation time. We found that an exposure time of 60 min was sufficient, and for almost all variables an optimal incubation time to discriminate between the low and high reference material. © 2019 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2335-2342, 2019.

Do repeated runs of a cell saver device increase the pro-inflammatory properties of washed blood?

OBJECTIVE: Intra-operative cell salvage is increasingly used, especially in longer cases with continuing blood loss. However it is unknown if the quality of processed blood is affected when larger quantities of blood are processed. We hypothesized that the quality of the washed blood decreases after multiple runs. METHODS: Intra-operative cell salvage was performed in 42 consecutive patients undergoing cardiac surgery. When 1250 ml of blood was collected in the blood collection reservoir, this was processed and returned to the patient. In 21 patients more than 2500 ml of blood was collected during the whole procedure, thus allowing at least two subsequent runs with the auto-transfusion device. Blood samples were drawn from the blood collection reservoir of the cell saver device before, and from the processed blood after each run. RESULTS: After the first run interleukin-6 concentrations were reduced with 85% (from 21+/-35 microg/l to 3.1+/-4.4 microg/l), whereas after the second run 72% was removed (63+/-69 microg/l to 17.6+/-25.3 microg/l). Leukocyte counts almost doubled after both processing runs (from 2.6+/-1.5 x 10(9)/l to 5+/-3.6 x 10(9)/l) and from 3.9+/-2.2 x 10(9)/l to 7.7+/-5.9 x 10(9)/l), hemoglobin concentration (14.8+/-1.6 mmol/l vs 15.0+/-1.1 mmol/l), free hemoglobin (2.3+/-1.6g/l vs 2.1+/-1.4 g/l) and platelet counts (18+/-9 x 10(9)/l vs 28+/-23 x 10(9)/l) were not different between the two runs. CONCLUSIONS: Our results suggest, based on interleukin-6 and free hemoglobin washout that the quality of the processed blood remains constant with multiple runs of the cell saver device.

In vitro blood flow model with physiological wall shear stress for hemocompatibility testing-An example of coronary stent testing.

Hemocompatibility of blood contacting medical devices has to be evaluated before their intended application. To assess hemocompatibility, blood flow models are often used and can either consist of in vivo animal models or in vitro blood flow models. Given the disadvantages of animal models, in vitro blood flow models are an attractive alternative. The in vitro blood flow models available nowadays mostly focus on generating continuous flow instead of generating a pulsatile flow with certain wall shear stress, which has shown to be more relevant in maintaining hemostasis. To address this issue, the authors introduce a blood flow model that is able to generate a pulsatile flow and wall shear stress resembling the physiological situation, which the authors have coined the "Haemobile." The authors have validated the model by performing Doppler flow measurements to calculate velocity profiles and (wall) shear stress profiles. As an example, the authors evaluated the thrombogenicity of two drug eluting stents, one that was already on the market and one that was still under development. After identifying proper conditions resembling the wall shear stress in coronary arteries, the authors compared the stents with each other and often used reference materials. These experiments resulted in high contrast between hemocompatible and incompatible materials, showing the exceptional testing capabilities of the Haemobile. In conclusion, the authors have developed an in vitro blood flow model which is capable of mimicking physiological conditions of blood flow as close as possible. The model is convenient in use and is able to clearly discriminate between hemocompatible and incompatible materials, making it suitable for evaluating the hemocompatible properties of medical devices.

In vitro hemocompatibility testing: The importance of fresh blood.

The use of unactivated blood for hemocompatibility testing is essential to obtain reliable results. Here, the authors study the influence of heparinized whole blood storage time and temperature on blood activation and evaluate the importance of initiating hemocompatibility tests within 4 h of blood collection. Blood from healthy volunteers was collected and analyzed with minimal delay, after 30 min and after 60 min of storage at room temperature, 30 or 37 °C. In addition, blood was analyzed after 1, 2, or 4 h of storage at room temperature. Platelet count, mean platelet volume, platelet binding capacity to collagen and thromboxane B2 were measured to assess platelet function, complement complex C5b-9 and elastase were measured to assess activation of the inflammatory response system, and thrombin-antithrombin III was measured to assess activation of the coagulation system. Furthermore, free hemoglobin was measured in platelet poor plasma as an indicator for red blood cell damage. The authors found that storage at 30 °C significantly increased platelet and coagulation activity after 60 min and storage at 37 °C significantly increased platelet, coagulation, and white blood cell activity after 60 min. Storage at room temperature significantly decreased platelet binding to collagen after 4 h and increased platelet activity after 1 h onward and white blood cell activity after 4 h. Their results show that short-term storage of heparinized whole blood significantly influences biomarkers over time, especially at 30 and 37 °C compared to room temperature. However, blood stored at room temperature for 4 h is also affected. In particular, platelet function and white blood cell activity are significantly influenced after 4 h of stationary storage at room temperature; therefore, the authors propose that hemocompatibility tests should be initiated well within 4 h of blood collection, preferably within 2 h.

Intraoperative cell salvage during cardiac surgery is associated with reduced postoperative lung injury.

OBJECTIVES: In addition to its blood-sparing effects, intraoperative cell salvage may reduce lung injury following cardiac surgery by removing cytokines, neutrophilic proteases and lipids that are present in cardiotomy suction blood. To test this hypothesis, we performed serial measurements of biomarkers of the integrity of the alveolar-capillary membrane, leucocyte activation and general inflammation. We assessed lung injury clinically by the duration of postoperative mechanical ventilation and the alveolar arterial oxygen gradient. METHODS: Serial measurements of systemic plasma concentrations of interleukin-6 (IL-6), myeloperoxidase, elastase, surfactant protein D (SP-D), Clara cell 16 kD protein (CC16) and soluble receptor for advanced glycation endproducts (sRAGEs) were performed on blood samples from 195 patients who underwent cardiac surgery with the use of a cell salvage (CS) device (CS, n = 99) or without (CONTROL, n = 96). RESULTS: Postoperative mechanical ventilation time was shorter in the CS group than in the CONTROL group [10 (8-15) vs 12 (9-18) h, respectively, P = 0.047]. The postoperative alveolar arterial oxygen gradient, however, was not different between groups. After surgery, the lung injury biomarkers CC16 and sRAGEs were lower in the CS group than in the CONTROL group. Biomarkers of systemic inflammation (IL-6, myeloperoxidase and elastase) were also lower in the CS group. Finally, mechanical ventilation time correlated with CC16 plasma concentrations. CONCLUSIONS: The intraoperative use of a cell salvage device resulted in less lung injury in patients after cardiac surgery as assessed by lower concentrations of lung injury markers and shorter mechanical ventilation times.

Biomarkers of lung injury in cardiothoracic surgery.

Diagnosis of pulmonary dysfunction is currently almost entirely based on a vast series of physiological changes, but comprehensive research is focused on determining biomarkers for early diagnosis of pulmonary dysfunction. Here we discuss the use of biomarkers of lung injury in cardiothoracic surgery and their ability to detect subtle pulmonary dysfunction in the perioperative period. Degranulation products of neutrophils are often used as biomarker since they have detrimental effects on the pulmonary tissue by themselves. However, these substances are not lung specific. Lung epithelium specific proteins offer more specificity and slowly find their way into clinical studies.

Pulsatile cardiopulmonary bypass and renal function in elderly patients undergoing aortic valve surgery†.

OBJECTIVES: To evaluate if pulsatile cardiopulmonary bypass (CPB) has any protective influence on renal function in elderly patients undergoing aortic valve replacement (AVR). METHODS: Forty-six patients (≥ 75 years old) with aortic valve stenosis underwent AVR with either pulsatile perfusion (PP) or non-pulsatile perfusion (NP) during CPB. Haemodynamic efficacy of the blood pump during either type of perfusion was described in terms of the energy equivalent pressure and the surplus haemodynamic energy. Urine samples were collected before surgery, at sternum closure, and at 2 and 18 h of intensive care unit stay to detect acute kidney injury markers. Perioperative urine levels of N-acetyl-ß-D-glucosaminidase (NAG), kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin (NGAL) were assessed together with plasma creatinine, creatinine clearance (CCr) and 24-h haemodynamic monitoring. Normally distributed continuous variables were described as mean ± standard deviation and non-normally distributed data were presented as the median [25th-75th percentiles]. RESULTS: PP was characterized by a significantly higher amount of surplus haemodynamic energy transferred to the patients (P < 0.001), with lower mean systemic vascular resistance during CPB (P = 0.020) and during 18 h postoperatively (group-P = 0.018). No difference was found between pre- and postoperative CCr in the PP group (71 ± 23 vs 60 ± 35 ml/min, P = 0.27), while its statistically significant perioperative decrement was observed in the NP group (67 ± 24 vs 45 ± 15 ml/min, P < 0.001). The PP group showed significantly lower urinary levels of NAG at 18 h postoperatively (P = 0.008), and NGAL at sternum closure (P = 0.010), 2 h (P < 0.001) and 18 h (P = 0.015) postoperatively. CONCLUSIONS: Short-term PP in elderly patients showed higher safety for renal physiology than NP, resulting in better maintenance of glomerular filtration and lower renal tissue injury.

Elevated Urinary Connective Tissue Growth Factor in Diabetic Nephropathy Is Caused by Local Production and Tubular Dysfunction.

Connective tissue growth factor (CTGF; CCN2) plays a role in the development of diabetic nephropathy (DN). Urinary CTGF (uCTGF) is elevated in DN patients and has been proposed as a biomarker for disease progression, but it is unknown which pathophysiological factors contribute to elevated uCTGF. We studied renal handling of CTGF by infusion of recombinant CTGF in diabetic mice. In addition, uCTGF was measured in type 1 DN patients and compared with glomerular and tubular dysfunction and damage markers. In diabetic mice, uCTGF was increased and fractional excretion (FE) of recombinant CTGF was substantially elevated indicating reduced tubular reabsorption. FE of recombinant CTGF correlated with excretion of endogenous CTGF. CTGF mRNA was mainly localized in glomeruli and medullary tubules. Comparison of FE of endogenous and recombinant CTGF indicated that 60% of uCTGF had a direct renal source, while 40% originated from plasma CTGF. In DN patients, uCTGF was independently associated with markers of proximal and distal tubular dysfunction and damage. In conclusion, uCTGF in DN is elevated as a result of both increased local production and reduced reabsorption due to tubular dysfunction. We submit that uCTGF is a biomarker reflecting both glomerular and tubulointerstitial hallmarks of diabetic kidney disease.

Generation of platelet-derived microparticles in patients undergoing cardiac surgery is not affected by complement activation.

OBJECTIVE: The mechanisms causing the presence of platelet-derived microparticles in the circulation are unknown. In vitro platelets release platelet-derived microparticles in response to complement activation. This study evaluates the relationship between complement activation and levels of circulating platelet-derived microparticles in patients undergoing cardiac surgery. METHODS: Prospectively, 71 patients were included who underwent elective coronary artery bypass grafting with cardiopulmonary bypass. The patients were randomly allocated to one of the 3 groups: uncoated oxygenator, UnModified Surface (n = 25) or oxygenator coated with either BioPassive Surface (n = 25) or BioActive Surface (n = 21). Platelet-derived microparticles and terminal complement complexes were determined before bypass and after induction of anesthesia, 15 minutes after the start of cardiopulmonary bypass, at the end of cardiopulmonary bypass, and 30 minutes after administration of protamine sulfate. RESULTS: Demographic and cardiopulmonary bypass data were similar for the 3 groups. At the end of cardiopulmonary bypass, platelet-derived microparticle numbers were decreased in all 3 groups. No significant differences were observed among the groups at any sampling point. At the end of cardiopulmonary bypass, terminal complement complex concentrations were increased in all groups (P <.001), and significant differences among the groups were present (P =.002). CONCLUSIONS: Despite significant complement activation, no increase in numbers of circulating platelet-derived microparticles was found in the systemic blood of patients undergoing cardiac surgery with cardiopulmonary bypass. Thus complement activation in vivo does not necessarily affect generation of platelet-derived microparticles.