Plasma, expander

Gum-Saline. Gum is a galactoso—gluconic acid having molecular weight of approximately 1500. First used (16) in kidney perfusion experiments, gum—saline enjoyed great popularity as a plasma expander starting from the end of World War I. The aggregation state of gum depends on concentration, pH, salts, and temperature, and its coUoid oncotic pressure and viscosity are quite variable. Conditions were identified (17) under which the viscosity would be the same as that of whole blood. 

Albumin. Investigation iato the safety of bovine plasma for clinical use was undertaken ia the eady 1940s ia anticipation of wartime need (26). Using modem proteia chemistry methods, including electrophoresis and ultracentrifugation, it was shown that most of the human adverse reactions to blood substitutes were caused by the globulin fraction and that albumin was safe for parenteral use. Human albumin is now used extensively as a plasma expander ia many clinical settings. 

The IV solutions of plasma expanders include hetastarch (Hespan), low-molecular-weight dextran (Dextran 40), and high-molecular-weight dextran (Dextran 70, Dextran 75). Plasma expanders are used to expand plasma volume when shock is caused by bums, hemorrhage surgery, and otiier trauma and for prophylaxis of venous thrombosis and diromboembolism. When used in die treatment of shock, plasma expanders are not a substitute for whole blood or plasma, but tiiey are of value as emergency measures until die latter substances can be used. 

Solutions used to manage body fluids are often administered IV. Before administering an IV solution, the nurse assesses the patient s general status, reviews recent laboratory test results (when appropriate), weighs the patient (when appropriate), and takes the vital signs. Blood pressure, pulse, and respiratory rate provide a baseline, which is especially important when the patient is receiving blood plasma, plasma expanders, or plasma protein fractions for shock or other serious disorders. 

Dextrans are produced commercially for use as plasma substitutes (plasma expanders) which can be administered by intravenous injection to maintain or restore the blood volume. They can be used in applications to ulcers or bum wounds where they form a hydrophilic layer which absorbs fluid exudates. 

A summary of the properties of the different types of dextrans available is presented in Table 25.1. Dextrans for clinical use as plasma expanders must have moleeular weights between 40000 (= 220 glucose units) and 300000. Polymers below the minimum are excreted too rapidly fiom the kidneys, whilst those above the maximum are potentially dangerous because of retention in the body. In practice, infusions containing dextrans of average molecular weights of40000,70000 and 110000 are commonly encountered. 

HSA is used as a plasma expander in the treatment of haemorrhage, shock, burns and oedema, as well as being administered to some patients after surgery. For adults, an initial infusion containing at least 25 g of albumin is used. The annual world demand for HSA exceeds 3001, representing a market value of the order of US 1 billion. 

Poly(iV-vinyl pyrrolidone) - 1939 Blood plasma expander, binders rubbers ... 

In addition to murein, bacterial polysaccharides include dextrans—glucose polymers that are mostly al 6-linked and al 3-branched. In water, dextrans form viscous slimes or gels that are used for chromatographic separation of macromolecules after chemical treatment (see p.78). Dextrans are also used as components of blood plasma substitutes (plasma expanders) and foodstuffs. 

Hematological agents In clinical trials in patients undergoing PTCA/PCI, coadministration of bivalirudin with heparin, warfarin, thrombolytics, or GPIIb/llla inhibitors was associated with increased risks of major bleeding events compared with patients not receiving these concomitant medications. There is no experience with coadministration of bivalirudin and plasma expanders such as dextran. 

Plasma, plasma protein fractions, whole blood or plasma expanders may be required. 

The majority of blood substitutes currently in use function only as plasma expanders. These maintain blood pressure by providing vascular fluid volume after haemorrhage, burns, sepsis or shock. While standard electrolyte solutions, such as physiological saline, may be administered, their elfect is transitory as they subsequently dilfuse back out of the vascular system. 

Alternatively, colloidal plasma expanders (Table 9.3) are used. When administered at appropriate concentrations, they exert an osmotic pressure similar to that of plasma protein, hence vascular volume and blood pressure are maintained. The major disadvantages of colloidal therapy include its relatively high cost, and the risk of prompting a hypersensitivity reaction. Determined elforts to develop blood substitutes were initiated in 1985 by the US military, concerned about the issue of blood supply to future battlefields. 

Dextrans (polysaccharides Figure 9.1) of various molecular masses, usually 1, 40, 60, 70 or llOkDa, are often used as plasma expanders. These polysaccharides are produced naturally by... 

A 4% solution of gelatin (often modified, i.e. succinylated gelatin) is also used as a plasma expander. For this application, 500ml-ll of the sterile solution is infused slowly. In rare occurrences, infusion (particularly rapid infusion) of the gelatin solution has been known to initiate hypersensitivity reactions. After its infusion, gelatin is excreted relatively quickly and mostly via the urine. 

Larger volumes can only be safely removed if there is simultaneous albumin replacement intravenously (with about 8 g of albumin per litre of ascites). Synthetic plasma-expanders may not be greatly inferior to albumin in the short term. Transjugular intrahep-atic portal systemic shunting (TIPS) appears at least as effective as paracentesis in relieving refractory ascites without increasing mortality but with a raised risk of encephalopathy. 

The clinically used plasma expanders are classified as in table 4.6.1. 

They are most commonly used plasma expanders. It is polysaccharide isolated from beet sugar which is formed by the action of Leuconstec mesenteroides. It is available in mainly two forms depending upon the molecular weight. Dextran 70 (mol. wt. 70,000) available in 6% solution and Dextran 40 (mol. wt. 40,000) available in 10% solution. They are infused intravenously in the treatment of shock. Dextran 40 acts more rapidly than dextran 70. It decreases the blood viscosity and prevents the sludging of RBC s. Dextran 70 remains in circulation for longer period (upto 24 hrs) and is slowly excreted by glomerular filtration. 

Plasma expanders are not used in severe anaemia, cardiac failure, pulmonary edema and renal failure. 

Apart from colloidal plasma expanders crystalloid (electrolyte) fluids are used in certain clinical conditions. 

Cochrane Injuries Group Albumin Review. Human albumin administration in critically ill patients Systematic review of randomised controlled trials. BMJ 1998 317 235-40. de Jonge E, Levi M, Berends F, et al. Impaired haemostasis by intravenous administration of a gelatin-based plasma expander in human subjects. Thromb Haemost 1998 79 286-90. 

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