Effluent Blood Research Articles

Morphology of the respiratory vasculature of the mudskipper Boleophthalmus pectinirostris (Gobiidae: Oxudercinae).

The gross morphology of the circulatory system in the amphibious mudskipper, Boleophthalmus pectinirostris, conforms with the typical teleost configuration, in which gills and systemic vascular beds are connected in series. However, at the microscopic level, the vasculatures of the respiratory organs, the inner epithelium of the bucco-opercular cavity, gills and skin, all show specializations for aerial gas exchange. The epithelium of the bucco-opercular cavity is heavily vascularized by respiratory capillaries that are derived from systemic arteries of the head, mainly branches of the hyomandibular artery and the dorsal opercular artery. The respiratory circuit of the secondary lamellae of the gills consists of 15-17 channels running in parallel, unlike the lacuna-like blood space of aquatic fishes. The most notable specialization is found in the microcirculation of the respiratory papillae in the skin. Each respiratory papilla is supplied by an arteriole that is derived from a systemic artery, mainly the cranial artery in the head and the segmental artery in the trunk. The arteriole divides several times along its course to the apical region of a papilla, where the branches split into approximately 65 capillaries that radiate to the periphery of the papilla. The capillaries twist 5-10 times before they unite to form the venules that encircle maximally half the circumference of a papilla. A variable number of venules merge into a vein, which progressively coalesces with veins from other papillae. There is no morphological specialization that separates oxygen-rich effluent blood of the epithelia of the bucco-opercular cavity and the respiratory papillae of the skin from the oxygen-poor systemic venous blood. The ecophysiological implications of these findings are discussed in relation to the environmental conditions that B. pectinirostris experience during tidal cycles in the warm months and during overwintering.

The possibility of using effluent ionized calcium to assess regional citrate anticoagulation in continuous renal replacement therapy.

This study aimed to investigate whether effluent ionized calcium was an appropriate indicator to assess anticoagulant effect in continuous renal replacement therapy with regional citrate anticoagulation instead of post-filter ionized calcium. In total, 48 paired samples of effluent fluid and post-filter blood were obtained from critically ill patients who required continuous renal replacement therapy. All samples were taken for ionized calcium measurements and were assessed by point-of-care analyzer. Correlations and agreements between two methods were performed by Pearson linear analysis and Bland-Altman analysis accordingly. The mean post-filter ionized calcium was 0.42 ± 0.12 mmol/L, and mean ionized calcium level of effluent fluid was 0.39 ± 0.11 mmol/L. The ionized calcium level of effluent fluid was significantly correlated with post-filter ionized calcium in all continuous renal replacement therapy patients. Bland-Altman analysis showed that the mean difference of ionized calcium between two sampling sites in all continuous renal replacement therapy patients was -0.02 mmol/L with 95% confidence interval ranging from -0.09 to 0.04 mmol/L. The significant correlations and agreements were also demonstrated in continuous veno-venous hemofiltration, continuous veno-venous hemodialysis, and continuous veno-venous hemodiafiltration modalities separately. The effluent ionized calcium could be a considerable substitute for post-filter ionized calcium to monitor the validity of regional citrate anticoagulation in continuous renal replacement therapy with less blood loss.

Retrograde perfusion through superior vena cava reaches the brain during circulatory arrest.

The optimal technique for brain perfusion during circulatory arrest remains controversial. Concern exists that retrograde cerebral perfusion (RCP) via the superior vena cava (SVC) is unable to perfuse the brain. We evaluated whether RCP blood circulates through the brain parenchyma in humans during deep hypothermic circulatory arrest (DHCA). We hypothesized that a significant difference in the levels of S-100β (a protein with very high neuro-sensitivity) between the blood infused in the SVC and the effluent blood returning in the left carotid artery (CA) during RCP, should be regarded as a sign of the circulation of RCP blood through the brain parenchyma. We enrolled 10 non-consecutive patients undergoing elective arch-surgery using DHCA and RCP. Circulating S-100β levels were measured at baseline and immediately before DHCA. During DHCA and RCP the difference in S-100β between the SVC and the CA was evaluated after 10 minutes of arrest and immediately before resumption of the circulation. S-100β levels were evaluated using enzyme-linked immunosorbent assay (ELISA). Mean DHCA duration was 22.4±7.9 minutes. Mean S-100β level at baseline was 92.5±54.9 µg/L. After 10 minutes of DHCA the level of S-100β in the CA was significantly higher than in the SVC (936.9±326.3 vs. 810.9±307.4 µg/L, P=0.0021). This difference was enhanced at the second DHCA sample (1113.8±334.2 vs. 920.5±340.0 µg/L, P=0.0002). There was a statistically significant correlation between the duration of DHCA and the percent difference in S-100β level between the SVC and the CA (Pearson's correlation coefficient =0.902). RCP is able to perfuse the brain parenchyma in humans during DHCA.

Portable vibration-assisted filtration device for on-site isolation of blood cells or pathogenic bacteria from whole human blood

Isolation of specific cells from whole blood is important to monitor disease prognosis and diagnosis. In this study, a vibration-assisted filtration (VF) device has been developed for isolation and recovery of specific cells such as leukocytes and pathogenic bacteria from human whole blood. The VF device is composed of three layers which was fabricated using injection molding with cyclic olefin copolymer (COC) pellets consisting of: a top layer with coin-type vibration motor (Ф = 10mm), a middle plate with a 1μm or 3μm-pore filter membrane to separate of Staphylococcus aureus (S. aureus) cells or leukocytes (i.e. white blood cells) respectively, and a bottom chamber with conical-shaped microstructure. One milliliter of human whole blood was injected into a sample loading chamber using a 3μm-pore filter equipped in the VF device and the coin-type vibration motor applied external vibration force by generating a rotational fluid which enhances the filtration velocity due to the prevention of the cell clogging on the filter membrane. The effluent blood such as erythrocytes, platelet, and plasma was collected at the bottom chamber while the leukocytes were sieved by the filter membrane. The vibration-assisted leukocyte separation was able to finish within 200s while leukocyte separation took 1200s without vibration. Moreover, we successfully separated S. aureus from human whole blood using a 1μm-pore filter equipped VF device and it was further confirmed by genetic analysis. The proposed VF device provides an advanced cell separation platform in terms of simplicity, fast separation, and portability in the fields of point-of-care diagnostics.

Shear stress activation of platelet glycoprotein IIb/IIIa

When normal native or heparinised blood is forced under pressure through a filter with capillary sized holes, platelets aggregate during their passage through the filter. The effluent blood is collected from 0-3s (first phase) and between 10-20s (second phase); the platelets are counted, and the percentage retained is calculated. Aggregation in the first phase requires high shear, vWf and GP IIb/IIIa only, while divalent cations are essential for the second

Fat Intravasation from Intraosseous Flush and Infusion Procedures

Study hypothesis. The primary study objective was to delineate the procedural aspects of intraosseous (IO) infusions responsible for fat intravasation by testing the hypothesis that the fat content of effluent blood increases during IO infusions. Methods. IO cannulas were inserted into the proximal tibiae of 35 anesthetized swine (Sus scrofa, 50.1 ± 3.5 kg) and intravasated fat was assessed using a lipophilic fluoroprobe (Nile red) and by vascular ultrasound imaging. Effluent blood bone marrow fat was assessed at baseline, during flush, and with regimens of controlled infusion pressures (73–300 mmHg) and infusion flow rates (0.3–3.0 mL per second). Fat intravasation was also assessed with IO infusions at different tibial cannulation sites and in the distal femur. In 7 animals, the lipid uptake of alveolar macrophages and lung tissue assessed for fat embolic burden using oil red O stain 24 hours post infusion. Additionally, bone marrow shear–strain was assessed radiographically with IO infusions. Results. Fat intravasation was observed during all IO infusion regimens, with subclinical pulmonary fat emboli persisting 24 hours post infusion. It was noted that initial flush was a significant factor in fat intravasation, low levels of intravasation occurred with infusions ≤300 mmHg, fat intravasation and bone marrow shear–strain increased with IO infusion rates, and intravasation was influenced by cannula insertion site. Ultrasound findings suggest that echogenic particles consistent with fat emboli are carried in fast and slow venous blood flow fields. Echo reflective densities were observed to rise to the nondependent endovascular margins and coalesce in accordance with Stoke's law. In addition, ultrasound findings suggested that intravasated bone marrow fat was thrombogenic. Conclusion. Results suggest that in swine the intravasation of bone marrow fat is a common consequence of IO infusion procedures and that its magnitude is influenced by the site of cannulation and infusion forces. Although the efficacy and benefits of IO infusions for emergent care are well established, emergency care providers also should be cognizant that infusion procedures affect bone marrow fat intravasation.

Haematological and biochemical characteristics of the splenic effluent blood in schistosomal patients undergoing splenectomy.

To assess hematological and biochemical features of splenic effluent blood and their influence on the rise of hematological values after splenectomy. we studied 20 patients undergoing surgical treatment for schistosomatic portal hypertension. We collected blood samples for CBC, coagulation, bilirubin and albumin in the splenic vein (perioperative) and peripheral blood (immediately pre and postoperative periods). the splenic blood showed higher values of red blood cells, hemoglobin, hematocrit, platelet count, total leukocytes, neutrophils, lymphocytes, monocytes, eosinophils and basophils, as well as reduction of laboratory coagulation parameters in relation to peripheral blood collected preoperatively. In the postoperative peripheral blood there was an increase in the overall leukocytes and in their neutrophil component, and decreased levels of basophils, eosinophils and lymphocytes. The other postoperative variables of complete blood count and coagulation tests were not different compared with the splenic blood. The albumin values were lower postoperatively when compared to preoperative and splenic blood. There were higher values of direct bilirubin in the postoperative period when compared with the preoperative and splenic blood. Postoperative indirect bilirubin was lower compared to its value in the splenic blood. hematological and biochemical values of splenic effluent blood are higher than those found in peripheral blood in the presence of schistosomal splenomegaly. However, the splenic blood effluent is not sufficient to raise the blood levels found after splenectomy.

PD-0020 Pharmacokinetic Analysis of Percutaneous Hepatic Perfusion (PHP) of Melphalan in Patients with Hepatic Metastases from Melanoma

ABSTRACT Introduction PHP (Delcath Systems Inc., New York, NY) is a non-invasive regional therapy that isolates the liver using a series of catheters, allowing infusion of high doses of chemotherapy directly into the hepatic artery. Systemic toxicity is minimized by extracorporeal hemofiltration of effluent hepatic venous blood, which is then returned to the systemic circulation. A randomized phase III study was conducted to compare PHP of high-dose melphalan with best alternative care in patients with ocular or cutaneous melanoma metastatic to the liver. A pharmacokinetic analysis, including an evaluation of filter extraction efficiency, was performed in a subset of patients from this study. Methods Melphalan was perfused into the liver over 30 minutes via PHP at a maximum dose of 3.0 mg/kg of ideal body weight (maximum 220 mg/treatment). Extracorporeal hemofiltration was performed during and for 30 minutes after melphalan infusion. PHP was performed with patients under general anesthesia. Blood samples (7 mL) were collected during the first cycle of PHP melphalan simultaneously from the periphery (arterial line) and extracorporeal circuit (both pre- and post-filter). Sample collections were made at: baseline (peripheral only); 15 minutes after the start of the infusion; immediately post-infusion; 5, 10, 15, and 30 minutes post-infusion. Plasma concentrations of melphalan were determined by high-pressure liquid chromatography with ultraviolet detection. Data were analyzed using a non-compartmental approach with WinNonlin v5.2 (Pharsight Corporation, Mountain View, CA). Concentration-time profiles were constructed for each sampling location (i.e. three profiles/patient). Pharmacokinetic parameters were: maximum plasma concentration (Cmax); area under the concentration-time curve from time zero to final sample (AUClast) calculated using the linear trapezoidal method; and filter efficiency [defined as: (pre-filter AUClast) minus (post-filter AUClast) divided by (pre-filter AUClast)]. Download : Download full-size image Figure . Individual AUC by site, alter 3 0 mg/Kg (ideal body weight) melphalan Horizontal bars represent mean and 95% Cls Results Plasma samples were available from 48 patients, of which 40 were evaluable. Mean absolute melphalan dose was 191 mg (range, 137–220 mg) and duration of perfusion was 30 minutes (range, 16–52 minutes). Mean prefilter, postfilter and systemic Cmax values were 8726 ng/mL, 2330 ng/mL and 1429 ng/mL, respectively. Mean prefilter AUClast was 264,652 min*ng/mL, mean postfilter AUClast was 74,146 min*ng/mL and mean systemic AUClast was 50,777 min*ng/mL; individual patient data for AUClast are shown in the Figure. Mean filter extraction efficiency was 71.2% ± 10.4%. Filter efficiency did not change significantly with absolute melphalan dose (p = 0.86, Spearman) or theoretical rate of perfusion (p = 0.064, Spearman). Conclusion The mean filter extraction efficiency of the PHP filtration system is 71%, and results appear to be consistent across patients (narrow 95% CI intervals). These findings indicate that the filter removes most of the melphalan administered via PHP.

Use of Ultraviolet C (UVC) Radiation to Inactivate Infectious Hematopoietic Necrosis Virus (IHNV) and Viral Hemorrhagic Septicemia Virus (VHSV) in Fish Processing Plant Effluent

We determined the stability of infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV) suspended in either fish processing plant effluent blood water (EBW) or culture media and examined the effectiveness of UVC radiation to inactivate IHNV and VHSV suspended in both solutions. Without exposure to UVC, IHNV and VHSV were maintained in 4°C blood water for up to 48 hours without significant reduction in virus titer. However when exposed to UVC radiation using a low pressure mercury vapour lamp collimated beam, IHNV and VHSV were inactivated, and the efficacy of UVC radiation was dependent upon the solution and virus type being treated. A 3-log reduction for VHSV and IHNV in culture media was achieved at 3.28 and 3.84 mJ cm -2 , respectively. The UV dose needed for a 3-log reduction of VHSV in EBW was 3.82 mJ cm -2 . However, exposure of IHNV in EBW to the maximum UVC dose tested (4.0 mJ cm -2 ) only led to a 2.26-log-reduction. Factors such as particle size, and possible association of viruses with suspended EBW particulate, were not investigated in this study, but may have contributed to the difference in UVC effectiveness. Future work should emphasize improved filtration methods prior to UV treatment of processing plant EBW at an industrial scale.

Gross and fine anatomy of the respiratory vasculature of the mudskipper, Periophthalmodon schlosseri (Gobiidae: Oxudercinae)

To illustrate vascular modification accompanying transition from aquatic to amphibious life in gobies, we investigated the respiratory vasculatures of the gills and the bucco-opercular cavities in one of the most terrestrially-adapted mudskippers, Periophthalmodon schlosseri, using the corrosion casting technique. The vascular system of Pn. schlosseri retains the typical fish configuration with a serial connection of the gills and the systemic circuits, suggesting a lack of separation of O(2)-poor systemic venous blood and O(2)-rich effluent blood from the air-breathing surfaces. The gills appear to play a limited role in gas exchange, as evidenced from the sparsely-spaced short filaments and the modification of secondary lamellar vasculature into five to eight parallel channels that are larger than red blood cell size, unlike the extensive sinusoidal system seen in purely water-breathing fishes. In contrast, the epithelia of the bucco-opercular chamber, branchial arches, and leading edge of the filaments are extensively laden with capillaries having a short (<10 μm) diffusion distance, which strongly demonstrate the principal respiratory function of these surfaces. These capillaries form spiral coils of three to five turns as they approach the epithelial surface. The respiratory capillaries of the bucco-opercular chamber are supplied by efferent blood from the gills and drained by the systemic venous pathway. We also compared the degree of capillarization in the bucco-opercular epithelia of Pn. schlosseri with that of the three related intertidal-burrowing gobies (aquatic, non-air-breathing Acanthogobius hasta; aquatic, facultative air-breathing Odontamblyopus lacepedii; amphibious air-breathing Periophthalmus modestus) through histological analysis. The comparison revealed a clear trend of wider distribution of denser capillary networks in these epithelia with increasing reliance on air breathing, consistent with the highest aerial respiratory capacity of Pn. schlosseri among the four species.

Protein loss in critically ill patients during continuous veno-venous hemofiltration

To evaluate protein loss in critically ill patients with acute renal failure during continuous veno-venous hemofiltration (CVVH) and analysis the major factor impacting protein clearance. A analysis was carried out in eighteen (twelve male and six female) sepsis or severe acute pancreatitis patients with acute renal failure from September 2008 to September 2009. The average age was 45 years (39 - 62 years). CVVH was conducted for 24 h in all patients. Effluent volume, blood speed, ultrafiltration rate and transmembrane pressure (TMP) were 4000 ml/h, (277 ± 89) ml/h, (179 ± 4) ml/min and (173 ± 48) mm Hg (1 mm Hg = 0.133 kPa) respectively. Blood samples were collected before and after filtration in order to detect protein concentration. Ultrafiltrate was obtained hourly to measure protein concentration and calculate protein loss during session. Mean protein concentration was (231 ± 67) mg/L and protein loss was (22 ± 6) g/d in ultrafiltrate samples. The difference in serum protein level during hemofiltration was not significant [(56 ± 6) g/L vs. (55 ± 10) g/L, P > 0.05], while there was a weak, but statistically significant correlation between the ultrafiltrate protein concentration and the corresponding value for serum protein (r = 0.481, P < 0.05). However, there was a strong and statistically significant correlation between the ultrafiltrate protein concentration and the TMP (r = 0.564, P < 0.01). Stepwise multiple regression analysis showed that TMP and serum protein concentration played a pivotal role in ultrafiltrate protein loss. In addition to renal replacement therapy, serum protein would be cleared through hemofilter during CVVH. TMP and serum protein concentration are the main factors that affect protein loss in ultrafiltrate. As a result, it is necessary to take account of the protein loss in ultrafiltrate when setting nutritional schedule.

Glucose-Regulated Protein 78 and Platelet Deposition

To investigate the effect of rosuvastatin on platelet deposition under controlled shear rate conditions and to identify new platelet proteins involved in the interaction with the activating substrate. Platelet-vessel wall interaction and thrombosis take place under dynamic conditions involving the interaction of the exposed damaged vascular wall with the circulating blood cells and proteins. Blood was perfused over type I collagen at different wall shear rates, and platelet deposition was measured by confocal microscopy. Perfused effluent blood was collected, platelets were sequentially extracted based on differential protein solubility, and proteins were separated by 2D gel electrophoresis. Blockade of 3-hydroxy-3-methylglutaryl-coenzyme A reductase significantly reduced platelet deposition and modulated the expression pattern of 18 proteins in the platelet subproteome. Among them, an increase in platelet surface 78-kDa glucose-regulated protein (GRP78), a stress-inducible multifunctional endoplasmic reticulum protein, was clearly apparent. Immunoprecipitation of platelet GRP78 revealed its interaction with tissue factor. Moreover, blockade of surface GRP78 resulted in a substantial increase in platelet deposition and tissue factor procoagulant activity and in a decrease in clotting time. These findings demonstrate that blockade of 3-hydroxy-3-methylglutaryl-coenzyme A reductase reduces platelet deposition and inhibits GRP78 translocation from the platelet surface after shear and collagen activation. For the first time to our knowledge, this study reports on the presence and functional role of GRP78 in platelets and indicates that GRP78 has additional functions beyond those of a molecular chaperone.

Enterocyte Shedding and Epithelial Lining Repair Following Ischemia of the Human Small Intestine Attenuate Inflammation

BackgroundRecently, we observed that small-intestinal ischemia and reperfusion was found to entail a rapid loss of apoptotic and necrotic cells. This study was conducted to investigate whether the observed shedding of ischemically damaged epithelial cells affects IR induced inflammation in the human small gut.Methods and FindingsUsing a newly developed IR model of the human small intestine, the inflammatory response was studied on cellular, protein and mRNA level. Thirty patients were consecutively included. Part of the jejunum was subjected to 30 minutes of ischemia and variable reperfusion periods (mean reperfusion time 120 (±11) minutes). Ethical approval and informed consent were obtained. Increased plasma intestinal fatty acid binding protein (I-FABP) levels indicated loss in epithelial cell integrity in response to ischemia and reperfusion (p<0.001 vs healthy). HIF-1α gene expression doubled (p = 0.02) and C3 gene expression increased 4-fold (p = 0.01) over the course of IR. Gut barrier failure, assessed as LPS concentration in small bowel venous effluent blood, was not observed (p = 0.18). Additionally, mRNA expression of HO-1, IL-6, IL-8 did not alter. No increased expression of endothelial adhesion molecules, TNFα release, increased numbers of inflammatory cells (p = 0.71) or complement activation, assessed as activated C3 (p = 0.14), were detected in the reperfused tissue.ConclusionsIn the human small intestine, thirty minutes of ischemia followed by up to 4 hours of reperfusion, does not seem to lead to an explicit inflammatory response. This may be explained by a unique mechanism of shedding of damaged enterocytes, reported for the first time by our group.

Determination of carcinoembryonic antigen levels in peripheral and draining venous blood in patients with colorectal carcinoma

The problem of the relationship between blood carcinoembryonic antigen (CEA) levels and tissue CEA content in colorectal carcinoma, and the mechanisms for CEA release from tumor cells in tissue adjacent to the neoplasm is important to understanding the biology of colorectal carcinoma. It has not been adequately explained whether CEA in the peripheral blood is drained mainly by portal system blood or by the lymphatic system, or indeed by both systems. To study the behavior of CEA levels in peripheral blood (CEA-p) and venous effluent blood (CEA-d) among patients with colorectal tumors, who underwent curative operation. A total of 28 patients were studied (12 male [42.9%] and 16 female [57.1%], mean age 66.1 years [range: 43 - 84]). Immediately after laparotomy, peripheral venous blood was extracted by antecubital venous puncture and venous effluent blood was collected from the main drainage vein of the lesions. Values of CEA-p, CEA-d and the gradient between CEA-d and CEA-p that were less than 5.0 ng/mL were considered normal. Eight (28.6%) patients were stage A in Duke's classification, nine (32.1%) stage B and 11 (39.3%) stage C. The neoplasm was located in the rectum of 14 patients (50.0%), in the transverse colon in five (17.9%), in the sigmoid in four (14.3%), in the cecum and/or ascending colon in three (10.7%), and in the descending colon in two (7.1%). The histopathological examination revealed well-differentiated adenocarcinoma in all the patients. Only one patient (3.6%), Duke's classification stage C, presented neoplasm with venous invasion. The gradient between the CEA-p and CEA-d levels were normal in 25 patients (88.3%) and high in three (10.7%). The mean value for CEA-p was 3.8 +/- 4.1 ng/mL (0.1-21.1 ng/mL) and for the drained CEA (CEA-d) it was 4.5 +/- 4.3 ng/mL (0.3-20.2 ng/mL), without significant difference between these values. There was a significant difference between the mean value for CEA-p and CEA-d levels greater than 5 ng/mL. The CEA-p and CEA-d levels in the colorectal carcinoma patients were not shown to be different. The results from this study suggest that, in colorectal neoplasm without venous invasion, there may not be notable CEA drainage from the tumor by the portal vein effluent blood.

Effects of adenosine pretreatment on detection of free radicals in ischemic and reperfused canine gracilis muscle flaps by use of spin-trapping electron paramagnetic resonance spectroscopy

To determine whether adenosine pretreatment attenuates free radical production and muscle damage in ischemic and reperfused canine skeletal muscle. 9 healthy mixed-breed dogs. Dogs were anesthetized, and both gracilis muscles were isolated, leaving only the major vascular pedicle intact. Saline (0.9% NaCl) solution was injected into the artery supplying the control flap, whereas adenosine (10 mg) was injected into the contralateral artery. Ischemia was induced in both flaps for 4 hours. alpha-Phenyl-N-tert-butylnitrone was administered IV to each dog 1 hour prior to reperfusion. Following 15 minutes of reperfusion, effluent blood samples from each muscle flap were obtained and processed for spin-trapping electron paramagnetic resonance (EPR) spectroscopy. Muscle biopsy specimens were obtained for histologic evaluation, and dogs were euthanatized. EPR spectra of strong intensity were obtained from analysis of 5 of 9 paired samples. Signals identified were characteristic of oxygen- and carbon-centered free radical adducts. Signal intensity of spectra from adenosine-treated flaps was significantly less than that of control flaps; mean signal attenuation was 36% in the adenosine-treated group. Histologic evaluation of muscle flaps did not reveal significant differences between groups. Treatment of canine muscle flaps with adenosine prior to a period of ischemia reduced but did not completely attenuate free radical production after reperfusion. However, adenosine pretreatment did not affect histologic abnormalities.

A novel paracorporeal method for isolated rodent lung reperfusion.

The isolated perfused lung model is commonly used in small animals to study lung function after preservation and cold storage. Measurements of oxygenation, compliance, and capillary filtration coefficient (Kf) permit analysis of preservation solutions or modifications of these solutions. However, inter-investigator variability using different perfusates makes comparisons difficult. Whole blood perfusion more closely mimics the in vivo situation, but extracorporeal circulation may alter the physiologic integrity of the model. Paracorporeal support has been used, but this technique required mechanical ventilation of the support rodent and did not incorporate a method for determining Kf. We evaluated a less-invasive technique, of providing cross-circulatory syngeneic support, maintaining the ability to compute Kf. Angiocatheters were inserted into both femoral arteries and one femoral vein of the support rat. The venous cannula was connected to the pulmonary artery of the ex vivo lung block to provide inflow. Pulmonary effluent blood from the lung block was collected via a left atrial cannula and returned to the support rat via the femoral artery. A separate, height-adjustable column was included in the circuit for measurement of Kf. Each support rat was used to sequentially perfuse three double-lung blocks. The inflow sample to each lung block was analyzed for pH, pO2, pCO2, and hematocrit to follow alterations in support rat physiology. There were no statistical differences in the pH, PO2, or hematocrit. No significant differences were noted in the pO2 of the pulmonary effluent blood or the Kf; analyzed to determine whether the sequence of reperfusion affected the pulmonary function assessment. The syngeneic support rat delivers constant pressure systemic venous blood at stable physiologic parameters to the ex vivo lung block. Recirculation of the perfusate through the support rat diminishes the need to pool blood from donors, detoxifies and deoxygenates pulmonary effluent blood, and permits examination of sequential lung blocks. This technique represents a hybrid model between isolated perfused and orthotopic transplant models, maintaining Kf determination, a sensitive indicator of reperfusion injury. This technique could be applicable to reperfusion injury models of other organs (using arterial inflow instead) and may permit increased standardization among investigators.

Detection of free radicals in ischemic and reperfused canine gracilis muscle flaps by use of spin-trapping electron paramagnetic resonance spectroscopy.

To determine whether free radicals are produced in ischemic and reperfused canine skeletal muscle, whether free radicals can be detected from effluent blood by use of spin-trapping electron paramagnetic resonance (EPR) spectroscopy, and whether free radical-induced skeletal muscle damage is detectable by use of light microscopy. 6 healthy mixed-breed dogs. Dogs were anesthetized and both gracilis muscles were isolated, leaving only the major vascular pedicle intact. Ischemia was induced in 1 flap for 4 hours; the contralateral flap served as the control. Ischemic flaps were then reperfused for 15 minutes. alpha-Phenyl-N-tert-butylnitrone, a spin-trapping agent, was administered intravenously to each dog 1 hour prior to reperfusion. Following reperfusion, effluent blood samples from muscle flaps were obtained and processed for EPR spectroscopy. Muscle biopsy specimens were obtained for histologic evaluation, and dogs were euthanatized. Spin adducts were not detected in blood from control flaps. However, spin adducts were detected in all ischemic-reperfused muscle flaps. Principal signals identified were characteristic of oxygen- and carbon-centered radicals. Significantly more muscle damage was detected in ischemic-reperfused flaps, compared with control flaps. Free radicals may be an important component of injury induced by ischemia and reperfusion of canine skeletal muscle. Spin-trap adducts of free radicals can be detected in effluent blood of canine muscle flaps by use of spin-trapping EPR spectroscopy. Spin-trapping EPR spectroscopy may be useful for the study of antioxidants and free radical scavengers in attenuating ischemia and reperfusion-mediated skeletal muscle damage.

Continuous Renal Replacement Therapy in the Initial Management of Neonatal Hyperammonemia Due to Urea Cycle Defects

After completing this article, readers should be able to: 1. Describe the metabolic acidosis that may be seen in urea cycle defects. 2. Delineate the most important factor in determining neurologic outcome in urea cycle defects. 3. Explain the factors that affect the blood ammonia concentration in continuous renal replacement therapy (CRRT). 4. Delineate the most difficult issue in pursuing CRRT in neonates. 5. Describe the morbidities associated with CRRT. MP was born at 39 weeks' estimated gestational age by vaginal delivery to a 35-year-old gravida 3 para 2 woman who had an uncomplicated pregnancy. The 3- and 6-year-old female siblings of the patient were healthy. Apgar scores were 8 at 1 minute and 9 at 5 minutes. The newborn was discharged to home after a 2-day stay in the well baby nursery during which time she appeared to be alert and was breastfeeding appropriately. She presented to the emergency department less than 1 day later after her parents noted increasing lethargy and very poor feeding at home. She was admitted to the neonatal intensive care unit (NICU). Results of a complete blood count with differential count and C-reactive protein evaluation were unremarkable, but the patient progressed to worsening lethargy, respiratory failure, and abdominal distension requiring intubation within hours of admission. The anterior fontanelle was soft on admission physical examination. Further testing revealed a base deficit of 6.1 on arterial blood gas, serum ammonia level of 810 mcmol/L (1,134 mcg/dL), serum lactate level of 5.6 mmol/L (5.6 mEq/L), and serum pyruvate level of 0.06 mmol/L. Results of liver function tests were abnormal, and the infant had a prothrombin time of 35.9 seconds, a partial thromboplastin time of 54.3 seconds, and a fibrinogen concentration of 1.75 g/L (175 mg/dL). Genetic and nephrology consultations were requested immediately. Additional metabolic studies were obtained, including measurement of plasma amino …

Cerebrovenous oxygen saturation monitoring: practical considerations and clinical relevance.

Measurement of the saturation of brain effluent blood gives a global estimate of cerebral oxygenation. It may provide clinicians with information to assist in reducing secondary insults to the brain with potential benefits to a range of patients with actual or potential acute brain injury such as trauma and cardiac bypass procedures. The technology to continuously measure this variable is simple to use but requires attention to detail; it is limited in its ability to detect discrete regions of ischaemia or hyperaemia unless these are of sufficient magnitude to influence the saturation of brain effluent blood. There are few complications that result from this invasive technique and they are usually of a minor nature. The technique also enables research opportunities from the ability to sample blood as it leaves the cranium. Poor outcomes are seen in patients with traumatic brain injury who exhibit either reduced or increased cerebrovenous oxygen saturation and it remains to be seen if detection and correction of these anomalies will produce patient benefits.

In vivo manipulation and continuous measurement of muscle blood flow with venous effluent sampling.

1. An acute in vivo hindlimb skeletal muscle preparation was developed in anaesthetized sheep in order to facilitate studies of the effects of altered blood flow states on drug kinetics in skeletal muscle. 2. A continuous index of blood flow was recorded via ultrasonic Doppler probes on the femoral artery and vein. Skeletal muscle effluent blood was sampled via a catheter in the femoral vein proximal to the probe. Low- and high-blood flow states were achieved by direct femoral artery infusion of adrenaline (0.002-0.006 mg/min) or magnesium (0.4-1 mmol/min), which produced mean (+/-SD) stable flow states of 25+/-12 and 185+/-56% (both n = 5) of baseline, respectively. The correlation coefficients between arterial and venous Doppler frequency shifts in five sheep during and after adrenaline infusion were 0.96 (indicating these vessels probably supplied and drained common tissue). 3. The venous Doppler frequency shifts were calibrated against timed collections of the femoral vein outflow to provide estimates of the low and normal blood flow states (mean flows of 2.8+/-1.7 and 9.3+/-5.7mL/100 g per min; both n = 3) and against an indirect Kety-Schmidt method during low- and high-blood flow states (mean flows of 2.2+/-1.3 and 18.2+/-7.0 mL/100 g per min; both n = 5). There was a generally good agreement between the two methods. 4. The tissue was neither hypoxic nor acidotic in the low- or high-flow states and altering the flow produced no change in muscle oxygen consumption, suggesting the flow changes were largely due to changes in resistance vessel tone. 5. Postmortem femoral artery dye injection and dissection of stained tissues showed the artery supplied 657+/-96 g (n = 5) of skeletal muscle and 42+/-20 g (n = 5) of other tissues. 6. It is concluded that the method is suitable for sampling predominantly muscle effluent blood at low- or high-blood flow states according to experimental requirements.