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    Intraperitoneal nutrition in dogs : a possible alternative for nutritional support : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University
    (Massey University, 1999) Halsey, Todd R
    Prolonged protein-energy malnutrition in dogs and other species has serious and wide-ranging adverse effects on organ systems. Separating the effects of poor nutritional status from those of the underlying disease mechanism is difficult and has made documenting a significant improvement in the long-term survival of patients frustrating. Despite these problems, nutritional support continues to be an important component of the treatment in critically ill or injured patients. In Chapter 1 the consequences of prolonged malnutrition throughout the body are discussed and the methods of providing nutritional support assessed. For patients who have a functioning gastrointestinal tract (GIT), nutritional support should be provided so that as much of the GIT as possible is used. In companion animals, enteral nutrition can be provided in various ways, ranging from forced oral feeding to an indwelling jejunostomy tube. Enteral nutritional support is a more physiological route for nutrient absorption, is less likely to result in serious adverse effects and is cheaper than parenteral nutrition. However, there are circumstances under which the GIT cannot be utilised as the primary route for nutritional support. This prompted the development of intravenous parenteral nutrition. Administration of total daily caloric requirements necessitates the use of a central venous line and a continuous 18 to 24 hour infusion. Unfamiliarity with central venous catheters, expensive and the inability to provide 24 hour monitoring for critically ill patients has precluded the use of intravenous parenteral nutrition in many veterinary hospitals. For these reasons alternative routes of nutritional support have been examined. Chapter 2 examines the work achieved over the past 20 years by workers who have investigated the peritoneal cavity as an alternative route for parenteral nutritional support. The peritoneum is capable of absorbing electrolytes, dextrose, complex carbohydrates, amino acids, intact plasma proteins, lipids and particulate matter. Previous studies using experimental animal models have demonstrated that intraperitoneal nutritional support is feasible. The pilot study (Chapter 3) in this experimental series examined the physical, haematological, biochemical and peritoneal cytological response in dogs receiving a total nutrient admixture (TNA) comprised of dextrose, amino acids and a lipid emulsion administered into the peritoneal cavity by a repeat puncture technique. This study identified a number of significant adverse effects associated with intraperitoneal nutrition (IPN) when using a TNA given in sufficient quantities to meet 100% of daily energy requirements (RER). Acute non-septic peritonitis, hypoalbuminaemia, mild anaemia, electrolyte and glucose derangements, and sudden fluid shifts from the vascular space into the peritoneal cavity were the problems recognised. The study reported in Chapter 4 was undertaken to investigate the cause of the marked peritoneal inflammatory response and to pursue possible explanations lor the clinicopathological changes that occurred in the pilot study. This was achieved by administering the components of the TNA as individual nutrients and comparing the peritoneal response over a 5 day period. This study demonstrated that the lipid component of the TNA was responsible for the majority ot the peritoneal inflammation seen in the pilot study, causing a 13 fold greater increase in peritoneal total white cell count (TWCC) compared to a 5% amino acid solution and a 10% dextrose solution. Although there was a significant increase in peritoneal TWCC in dogs receiving the lipid emulsion, there were no signs supportive of a clinically significant peritonitis at the dose administered. The mild anaemia, hypoproteinaemia (particularly hypoalbuminaemia) and electrolyte disturbances noted in the pilot study were again seen in the study described in this chapter. Although well tolerated by the peritoneal cavity, 10% dextrose in the volume administered in Chapter 4 failed to supply enough calories on a daily basis to make this route of nutritional support feasible. It was decided to try and increase the percentage of daily caloric requirements supplied by using a dextrose polymer. This nutrient solution allowed more calories to be provided for a given osmolality without the risk of fluid shifts into the peritoneal cavity because of it's isotonic nature. The study presented in Chapter 5 identified that a 21.5% dextrose polymer solution caused an initial significant increase in peritoneal TWCC, which then declined to near baseline concentrations by the end of the study. It was concluded that twenty percent of resting energy requirements can be safely given to clinically healthy dogs in the form of a 10% dextrose solution, 5% amino acid solution, 10% lipid emulsion and a 21.5% dextrose polymer solution via a repeat abdominal puncture technique. Further studies are required before this form of nutritional support can be widely recommended to the veterinary profession.
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    Investigations into the feasibility of the intraperitoneal route for provision of nutritional support to companion animals : a thesis prepared in partial fulfilment of the requirements for the degree of Master of Veterinary Science, Massey University, 2000
    (Massey University, 2000) Barter, Linda
    Poor nutrition is associated with alterations in metabolism and intracellular enzyme activities, defects in the function of multiple body systems and impaired wound healing. Enteral nutrition is preferred over parenteral nutrition in most circumstances. A proportion of patients, however, are not suitable to receive nutrition via the enteral route and require parenteral nutritional support. Unfortunately, the use of intravenous parenteral nutrition is largely confined to referral institutions because of expense, potential complications and lack of 24-hour care facilities. A number of reports in the scientific literature suggest conventional parenteral nutrition solutions are well absorbed after delivery into the peritoneal cavity. This route of nutritional support may provide an alternative to currently available intravenous parenteral nutrition. The peritoneum is composed of a single layer of mesothelial cells built upon a basal lamina and underlying connective tissue. Within the connective tissue layer is a complex network of lymphatics and blood vessels. Mesothelial cells are biologically active, playing roles in local immune response, host defence and locally regulating inflammation and vascular tone. The large surface area of the peritoneum has huge absorptive potential. Water and solutes are able to traverse the mesothelial cell layer, travel through the interstitium and into the semi-permeable capillary network or lymphatics. Macromolecules are absorbed through dilated mesothelial intercellular spaces or 'stomata' and enter underlying lymphatic channels. These transport properties of the peritoneum have been exploited for many years in the technique of peritoneal dialysis and are the basis of intraperitoneal nutrition. Amino acids, glucose and lipid solutions have been demonstrated to be absorbed after intraperitoneal administration in rats, rabbits, dogs and people. Experimentally, intraperitoneally delivered nutrient solutions have been used to provide nutritional support for dogs and rabbits for periods up to 30 days. Side effects of intraperitoneal nutrition include fluid shifts into the peritoneal cavity and septic peritonitis. Careful control of volume and osmolality of the fluid infused and implementation of sterile technique should limit the occurrence of these problems. Current literature would suggest intraperitoneal nutrition is a practical and effective means by which to provide nutritional support. Originally used as a tool to detect intra-abdominal haemorrhage, diagnostic peritoneal lavage (DPL) is now used as an aid in the diagnosis of a wide variety of medical and surgical conditions of the abdomen. Diagnostic peritoneal lavage is reported to be highly sensitive in the detection of septic peritonitis. The technique of DPL would be easily combined with intraperitoneal nutrient instillation and may provide a useful means of monitoring the peritoneal cavity for potential sepsis during intraperitoneal nutrition. Two original studies are reported in this work. The first describes the suitability of glucose, amino acid and lipid solutions for instillation into the peritoneal cavity of the cat. Two cats, one who received intraperitoneal amino acids and the other intraperitoneal glucose, developed clinical signs attributable to hypovolemic shock. Another two cats received two doses of intraperitoneal lipids 24 hours apart and developed clinical signs consistent with peritonitis: abdominal pain, pyrexia and vomiting. Diagnostic peritoneal lavage performed two days after the second intraperitoneal lipid infusion in these cats returned fluid with elevated total nucleated cells counts, an increased proportion of neutrophils and no evidence of infectious organisms. Aerobic and anaerobic culture of DPL fluid grew no bacteria. These findings suggest that the lipid solution used in this study incited a clinically apparent, sterile peritonitis in these two cats. The second study was undertaken to investigate the effects, in a different species, of intraperitoneal administration of the same lipid solution used in the feline pilot study. Five rats received three doses of intraperitoneal lipid 24 hours apart and another five rats intraperitoneal saline infusions. Diagnostic peritoneal lavage, post mortem and histological examination of peritoneum and selected intra-abdominal organs was performed. No clinical signs of peritonitis were detected in any rat. Lipid treated rats, however, displayed cytological and histological evidence of peritoneal inflammation.