Fluid Therapy VET 2210 PDF

Fluid Therapy VET 2210  Physiology ▶60% of the body’s weight is water ▶ This is called the Total Body Water (TBW) ▶2/3rds intracellular (ICF) ▶1/3rd extracellular (ECF) ▶ 75% Interstitial Fluid (ISF) ▶ 25% Intravascular Fluid (IVF) In neonates, ~80% of weight is from...

Fluid Therapy VET 2210  Physiology ▶60% of the body’s weight is water ▶ This is called the Total Body Water (TBW) ▶2/3rds intracellular (ICF) ▶1/3rd extracellular (ECF) ▶ 75% Interstitial Fluid (ISF) ▶ 25% Intravascular Fluid (IVF) In neonates, ~80% of weight is from fluid!!  Blood Volume Circulating Blood Volume ▶ Dogs: 80-90 ml/kg ▶ Cats: 40-60 ml/kg ▶ Horses: 80 ml/kg Avg. Plasma Concentrations  Physiology Intracellular Fluid (ICF) ▶Fluid within the cells ▶Major electrolytes include POTASSIUM (K⁺) , MAGNESIUM (Mg2⁺), & PHOSPHATES (HPO₄2- ) ▶Difficult to measure ICF electrolytes so measure serum concentrations  Physiology Extracellular Fluid ▶In constant motion allowing nutrients, oxygen, and electrolytes to reach cells and removes waste products (homeostasis). ▶Major extracellular electrolytes include SODIUM (Na⁺), CHLORIDE (Cl⁻), & BICARBONATE (HCO₃⁻ )  Electrolytes Potassium (K⁺) ▶ Responsible for osmotic pressure within the cell ▶ Important in normal cell metabolism, maintenance of body functions, and generation of electrical potentials in muscles and nerves ▶ HYPOKALEMIA ▶Most common- requires supplementation ▶ HYPERKALEMIA ▶Less common - life threatening ▶ Renal abnormalities & urethral obstruction  Electrolytes Sodium (Na⁺) ▶Attracts water, therefore it is the primary factor for determining ECF volume and osmotic pressure ▶Balance of intake & excretion is via the KIDNEYS ▶ HYPONATREMIA ▶Causes an influx of water into the cells ▶ HYPERNATREMIA ▶Usually due to water loss (Dehydration)  Balance Acid Base Balance ▶Regulation of hydrogen ion concentrations in body fluid—expressed as pH ▶Normal pH of venous blood and ISF is ~7.35 ▶Normal pH of arterial blood is 7.4 ▶Major complications and death can occur if the pH falls below 7.6 for more than a few hours ▶3 systems to control pH are blood buffers, lungs, and kidneys  Balance ▶ACIDOSIS: high hydrogen ion (H⁺) concentration expressed as a LOW pH ▶ Can make animals become hyperkalemic due to potassium being driven OUT of the cells ▶ALKALOSIS: low hydrogen ion (H⁺) concentration expressed as a HIGH pH ▶ Can make animals become hypokalemic due to potassium being driven INTO the cells  Terms ▶ Osmosis: Net movement of water across a semipermeable membrane caused by concentration differences of solutes across that membrane ▶ Normal osmolarity of canine blood is 280- 310 mOsm/l ▶ Osmotic Pressure: Pressure required to stop the movement of a fluid in a semi-permeable membrane - Pressure required to stop osmosis  Terms ▶ Hydrostatic Pressure: Pressure on any point on a fluid that is not moving ▶ Oncotic Pressure (Colloid Osmotic Pressure): Pressure exerted by large molecular weight molecules or plasma proteins in plasma that tends to pull water into the intravascular space ▶ Normal oncotic pressure of plasma is 20-30 mm/Hg  Tonicity ▶ Isotonic: Similar to plasma – No shift in fluids or cell structure ▶ 0.9% NaCl ▶ Hypotonic: Moves IVF to interstitial & intracellular space ▶ 2.5% Dextrose ▶ Cells Swell / Burst ▶ Hypertonic: Pulls ISF & ICF into the intravascular space ▶ 7% Sodium Chloride ▶ Cells Shrivel  Determining Fluid Needs History ▶Include food/water intake ▶Include urination/defecation information and vomiting history ▶Consider exposure to extreme heat, exercise, fever, etc ▶Include current/previous medications Exam ▶Skin turgor, position of eye in orbit, body temperature, mm color/tackiness, pulse rate/strength, CRT, heart rate should be checked  Determining Fluid Needs Lab Tests - Vital in determining electrolyte loss and fluid imbalances and to monitor Tx ▶ Hematocrit & Total Plasma Protein (TPP) ▶ Increased suggest fluid loss from the intravascular space resulting in dehydration ▶ Urine Specific Gravity ▶ Indicates kidneys ability to concentrate urine ▶ Serum Chemistry ▶ Determines the functional status of organs and the electrolyte imbalances Common abnormalities: hemoconcentration, azotemia, hypernatremia, elevated albumin  Factors in Abnormal Fluid Loss ▶Vomiting/Diarrhea ▶Increased Respiration (panting) in dogs ▶Disease with accompanying polyuria ▶Chronic or acute injury causing fluid loss ▶Disease or injury preventing or decreasing fluid intake orally  Routes of Administration Oral ▶GI tract must be functioning properly ▶Use with maintenance needs only Subcutaneous ▶Choice With Small Volumes ▶DO NOT Give SQ To: DEHYDRATED, HYPOTHERMIC, & HYPOTENSIVE ▶Cannot Give 5% Dextrose and H₂O Solution (D5W) ▶Causes Skin Slough  Routes of Administration Intravenous ▶ Choice when treating: DEHYDRATED, CRITICALLY ILL, HYPOVOLEMIC, & METABOLIC DISORDERS ▶ Has the most effect on blood volume ▶ Central venous catheters must be used with hypertonic solutions to avoid hemolysis Intraosseous ▶ Use In Young Or Severely Debilitated Patients ▶ Administered Through Head Of Femur / Humerus  Factors That Influence the Rate of Fluid Administration Poor Perfusion ▶Due to dehydration or hypovolemia ▶Must receive immediate IV fluid replacement to increase vascular volume ▶Monitor closely to ensure the animals’ HEART, KIDNEYS and LUNGS can handle the load Cardiovascular and renal abnormalities ▶Cannot tolerate rapid fluid infusion ▶Use CVP monitoring to determine rate of fluid administration  Contraindications for Fluid Therapy ▶Pulmonary edema or conditions that may result in fluid shifting into the lungs ▶Contraindications for rapid fluid therapy ▶Pulmonary contusions ▶Existing pulmonary edema ▶Brain injury ▶Congestive heart failure Types of Fluid  Crystalloid Solutions ▶ Contain electrolyte and non-electrolyte substances that can pass thru cell membranes and enter ALL BODY COMPARTMENTS ▶Often recommended initially in TX of acute blood loss ▶Routinely used due to low cost and versatility ▶These solutions are further broken down into replacement or maintenance solutions  Crystalloid Solutions Physiologic Saline ▶0.9% solution of NaCl ▶Osmolality of 308 mOsm/L so is sometimes referred to as ISOTONIC/PHYSIOLOGIC SALINE ▶Used to increase plasma or correct a sodium deficiency ▶Non-balanced solution  Crystalloid Solutions Lactated Ringer’s (LRS) ▶Most commonly used and versatile ▶Balanced electrolyte replacement solution that can be administered by any route ▶Also acts as a buffer against ACIDOSIS ▶Should Never Be Combined With Blood Transfusions ▶Contains Potassium So It Should Never Be Given To Obstructed Cats  Crystalloid Solutions Dextrose in 5% water ▶Non-balanced solution that contains only dextrose ▶Provides Approximately 170 kcal/L ▶Cannot Be Given Subcutaneously  Crystalloid Solutions Ringers Solution ▶Balanced replacement solution that contains more sodium, calcium, and chloride than lactated ringers Normosol-R ▶Balanced, multiple electrolyte solutions that buffer against acidosis and may prevent potential incompatibilities with BLOOD TRANSFUSIONS Normosol-R is for REPLACEMENT Normosol-M is for MAINTENANCE  Crystalloid Solutions Hypertonic saline: 3% NaCl, Side Effects 5% NaCl, 7% NaCl HYPERNATREMIA ▶Rapidly expand plasma HYPERCHLOREMI volume A HYPOKALEMIA ▶Increase cardiac output METABOLIC and increase blood ACIDOSIS pressure VENTRICULAR ▶3-5% NaCl also decrease ARRHYTHMIAS intracranial pressure and UNCONTROLLED BLEEDING WILL may be useful for cerebral WORSEN edema Colloid Solutions ▶ Contain large molecular weight particles that cannot cross cell membranes—they are confined to the VASCULAR SPACE ▶They can hold fluid in the vascular space as well as draw fluid from the interstitial space into the vascular space ▶Useful For Cerebral & Pulmonary Edema ▶Treatment: HYPOVOLEMIC or SEPTIC Shock ▶ Hypoalbuminemia, Blood Loss, Sepsis, & Hypotension  Colloid Solutions Colloid Solutions cont Dextran 40 and Dextran 70 ▶Shock ▶May cause ALLERGIC REACTION or CLOTTING DEFICITS Hetastarch ▶HYPOVOLEMIA & HYPROTEINEMIA ▶Fewer Side Effects Than Dextrans ▶Expensive  Colloid Solutions Plasma ▶Used with COAGULATION / CLOTTING DEFICIENCIES Whole Blood ▶Transfusions 25% Human Serum Albumin (HSA) ▶Used For Hypoalbuminemia Patients  IV Delivery Systems IV line ▶ With or without a fluid pump ▶ Make sure to match brands of extension sets and t-sets as well as with the infusion pump Burette ▶ Fluid chambers that hold 150mls ▶ Markers are in mls allowing for accurate admin to small animals  IV Delivery Systems Administration set sizes: ▶ 10 ggt/mL(mL/hr) ▶ 6 ggt/minute ▶ 15 ggt/mL(mL/hr) ▶ 4 ggt/minute ▶ 20 ggt/mL(mL/hr) ▶ 3 ggt/minute ▶ 60 ggt/mL(mL/hr) ▶ 1 ggt/minute Math :(  Evaluating Volume of Fluids Required: Maintenance Sensible water loss Normal Fluid ▶ Loss of water, nutrients, and Loss minerals thru urine Cat: 40 ▶ Measurable ml/kg/day Dog: 60 Insensible water loss ml/kg/day ▶Loss of water thru the respiratory tract (panting) and feces  Evaluating Volume of Fluids Required: Maintenance Maintenance fluids Allometric Scale ▶The daily intake of water, Dogs:132 x nutrients, and minerals BW(kg)¾ match the daily loss of OR the substances Cats: 80 x BW(kg)¾ Daily Maintenance: Basal Metabolic BW (kg) x 60 ml/kg/day calculation: 30 x BW(kg) + 70 Hourly Maintenance: 2-4ml/kg/hr  Evaluating Volume of Fluids Required: Replacement ▶In fluid abnormalities, due to fluid loss, the patient needs to bring the TBW (Total Body Water) back to a normal state ▶Acute losses can be replaced within 6-8 hours ▶Chronic losses should be replaced over 24 hours  Evaluating Volume of Fluids Required: Replacement ▶ 1 L fluid = 1 kg Body wt Replacement or Calculation: ▶ 1 lb loss of body weight % dehydration x = ~455 ml of fluid loss Bw (kg) x 1000 ml (1 pint = 473 ml)) Degree Dehydration Clinical Signs