Fluidtherapy is supportive. The underlying disease process that caused the fluid,electrolyte and acid base disturbances in the patient must be diagnosed andtreated appropriately. Normal homeostatic mechanisms allow the clinicianconsiderable margin for error in fluid therapy, provided that the heart andkidneys are normal (Stephen P. DiBartola and Shane Bateman) WhyShould we Give Fluids :• Correct dehydration• Correct acid-baseabnormalities d/t disease• Correct electrolyteabnormalities• Deliver drugs ina constant-rate infusion• Preventdehydration (GI disease)• Diuresis (renaldisease, toxicities)Signsof dehydration:PercentDehydration· <5 Not detectable · 5-6 Subtle loss of skin elasticity · 6-8 Definite delay in return of skin to normalposition Slight prolongation of capillaryrefill time Eyes possibly sunken in orbits Possibly dry mucous membranes · 10-12 Tented skin stands in place Definite prolongation ofcapillary refill time Eyes sunken in orbits Dry mucous membranes Possibly signs of shock(tachycardia, cool extremities, rapid and weak pulses) · 12-15 Definite signs of shock Death imminent(Muir WW, DiBartola SP: Fluid therapy. In Kirk RW, editor: Current veterinarytherapy VIII, Philadelphia, 1983, WB Saunders, p 33.
) Diagnosing Dehydration:• Physical exam• Weight loss– PCV (HCT) – increased• albumin or total protein increased• BUN, creatinine – increased =”Prerenal azotemia”• Skin tenting test – >3 sec indicatedehydration Components of Fluid Therapy: Fluid therapy containsthree components that should be taken into consideration.1. Fluid deficit2. Maintenancerequirement3. On-goinglosses Fluid deficit: It is the deficit of plasma volumecalculated by multiplying weight in Kgs by percent dehydration which gives thefluid deficit in litres• Fluid req(L) = Weight (Kg) X %dehydration Maintenance requirement: The maintenancefluid requirement is the volume needed per day to keep the animal in balance(i.e.
, no net change in body water).· Usually40-60 ml/kg/day On-going Losses: These are lossesthat are occurring during the course of treatmentIt includeslosses related to vomiting, diarrhea, polyuria, large wounds or burns, drains,peritoneal or pleural losses, panting, fever, and blood loss Rate of Administration:• Rate of fluid to be administered isdetermined by the magnitude and rapidity of fluid loss• In Normal cases (peri-operative) it is10ml/kg/hr • In case of shock – crystolloids 80-90ml/kg/hr colloids 20ml/kg/hr • 1/4th to ½ of fluid defecitshould be administerd over a period of 2-3 hrs• Reminder of the deficit + maintenancereq. + ongoing losses should be administered over a period of 24 hrs • Severe ongoing losses (e.g., vomitingand diarrhea in a patient with acute gastroenteritis) may necessitate rapidadministration to keep pace with contemporary fluid loss• It usually is not necessary to replacethe hydration deficit rapidly in chronic diseases, it should be done over aperiod of 24 hours Monitoring While on Fluids:• Weigh patient daily• Auscult the lungs – presence of thefollowing signs indicate overhydration– Crackles– Wheezes– Serous nasal discharge• Urine production – 1-2ml/kg/min• Central venous pressure • Overdose: – Serous nasal discharge – Dyspnea, crackles – Restlessness– Decreased PCV, TP– Increased BP AdministrationRoutes• Oral – If the stomach works, use it!– Safest route if tolerated• Subcutaneous– Works well in most animal – Sometimes need to use multiple sites– Can’t add glucose, large quantity KCl,or some drugs• Intravenous– Best route in dehydrated animals– Possible problems:• Volume overload• Catheter reactions (swelling, fever)• Intraosseous • If situation is dire and no vein accessible• Into the medullary (bone marrow)cavity of long bones– Femur or Humerus are commonly used– Used frequently in birds Types of Fluids:• Crystalloids– 0.9% NaCl – Lactated Ringers Solution– Ringers Solution– 5% Dextrose in water– Plasmalyte, Normosol, etcCrystalloidFluids• Isotonic– Mimic plasma electrolyteconcentrations, NS • Hypertonic– Osmolality higher than plasma, RL Lactated Ringer’sSolution• Composition closely resembles ECF– Contains physiological concentrationsof: sodium, chloride, potassium, and calcium– Also contains lactate, which ismetabolized by the liveràalkaline-forming– Becausesmall animals that are sick or under anesthesia tend towards acidosisSaline• 0.9% Sodium chloride = ISOTONIC• Lacking in K+, Ca2+• Used for hyperkalemia, hypercalcemia • Used as a carrier for some drugs DextroseSolutions• 5% dextrose is isotonic • 25%, 50% dextrose commonly found• Used for hypoglycemia, neonates,hyperkalemia, as part of Total Parenteral NutritionColloidsColloids arelarge-molecular-weight substances that are restricted to the plasma compartmentin patients with an uncompromised intact endothelium Natural Colloids• Blood products: – Whole blood– Plasma– Platelet-rich plasma– Packed RBC’s SyntheticColloids• Dextrans, Hetastarch • Used when quantity of a crystalloid istoo great to be able to infuse quickly• Stays within the vasculatureà maintainblood pressure • Duration of effect is determined bymolecular size: bigger = longer– Small volumes produce immediate increasesin blood pressure