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CHAPTER 2 Part 2 PATIENT PREPARATION IV CATHETERS: catheters are ideal for all anesthetic procedures Can provide IV fluids for support during surgery (blood loss, dehydration, prevent/treat hypotension) Allows injection of medications such as antibiotics and analgesics and allows constant-rate-infusions Provides access to a vein in an emergency (cardiac arrest, seizures ). Do not remove until animal is fully awake! Allows irritating agents to be injected (ex: thiopental) Allows injection of incompatible drugs PATIENT PREPARATION IV CATHETERS: Choose catheter size based on patient’s size and need Risks with catheter placement: AIR- always remove air from IV line before connecting to patient BROKEN TIP- don’t repeatedly advance and retract the stylet OVERHYDRATION- can avoid by using infusion pump or calculate drips/sec signs of over-hydration: eye/nose discharge, swelling of conjunctiva, SQ edema, increased lung sounds and respiration rate, dyspnea, coughing, restlessness, hemodilution SEPSIS- wipe area of catheter placement with an antiseptic and injection ports with alcohol HASTY INJECTION OF DRUGS – Just because the catheter is there, doesn’t mean all drugs should be given IV PATIENT PREPARATION IV FLUIDS: the patient’s infusion rate will depend on body weight and procedure Fluids during surgery/anesthesia: 5-10 mL/kg/hr (10mL/kg/hr is typical for the 1st hour, then reduced to 5mL/kg/hr for the remainder of the procedure) intended to compensate for vasodilation and fluid loss during anesthesia/surgery Isotonic, polyionic replacement crystalloids are the first choice for fluid therapy in healthy patients. PATIENT PREPARATION IV FLUIDS: fluid rates can be adjusted for those patients that are compromised CV disease Respiratory disease Fluid rates for these patients are often dropped to 5ml/kg/hr An animal with excessive hemorrhage or low blood pressure during surgery can have fluid rates increased Dogs: up to 40mL/kg/hr for max of 1 hour Cats: up to 20ml/kg/hr for max of 1 hour A quick way to estimate amount of fluids to give:*Give ~3mL of fluid for every 1mL of blood loss PATIENT PREPARATION ANIMALS IN SHOCK: these patients need even more rapid fluid rates Dogs: 50-90mL/kg/hr Cats: 40-60mL/kg/hr ¼ of the calculated dose is given and then patient re- evaluated (a 10-20mL/kg bolus) Animals in shock may show the following signs: Pale mucous membranes Low blood pressure Slow heart rate PATIENT PREPARATION IV FLUIDS: drip sets (administration sets) help determine how fast the fluids are administered Patients greater than 10kg use a macrodrip set Macrodrip sets are either 10gtt/mL or 15gtt/mL VTI has 15gtt/mL sets Patients less than 10kg use a microdrop set Microdrip sets are 60gtt/mL PATIENT PREPARATION IV FLUID ADMINISTRATION SETS MACRO MICRO PATIENT PREPARATION IV FLUID ADMINISTRATION: most clinics have an IV fluid pump. The pump controls how many drops of fluid are delivered to the patient over a period of time. If no pump is available, the anesthetist will need to calculate how many drops of fluid should be administered to the patient in a period of time as well as monitor the fluids closely. PATIENT PREPARATION MATH Step 1: Obtain the patient’s weight in kgs. If the patient’s weight was obtained in pounds, then you must divide by 2.2 Step 2: REMEMBER THE SURGICAL FLUID RATE: 10mL/kg/hr. Multiply the patient’s weight in kgs by 10. This will give you how many mLs the patient should receive in 1 hour known as the infusion rate. Step 3: Determine the drip set necessary for the patient based on weight. Step 4: Multiply the patient’s infusion rate by the drip set. Step 5: Divide the number from Step 4 by 3600 (because there are 3600 seconds in 1 hour). THIS FINAL ANSWER WILL TELL YOU HOW MANY DROPS OF FLUID EACH SECOND THE PATIENT WILL RECEIVE WHILE UNDER ANESTHESIA. PATIENT PREPARATION Patient weighs 6 kg. Surgical fluid rate is 10mL/kg/hr: 6 x 10 = 60 mL/hr Patient needs microdrip set: 60 x 60 = 3600 3600/3600 = 1 drop/sec Patient weighs 12 kg. Surgical fluid rate is 10mL/kg/hr: 10 x 12 = 120 mL/hr Patient needs a macrodrip set: 120 x 15 = 1800 1800/3600 = 0.5 drops/sec 0.5 drops/sec is impossible to count, but if we multiply by 10 it will tell us how many drops to administer in 10 seconds 0.5 x 10 = 5 drops/10 sec PATIENT PREPARATION:Fluid Administration •Body fluids consist of water and solutes. •Water is 60% of body weight. •It is divided into ICF and ECF (fluid in the vessels and fluid between the cells) •The other 40% is solutes PATIENT PREPARATION FLUID ADMINISTRATION Body fluid solutes: ions large plasma proteins or colloids, small nonionic particles such as glucose and small proteins Electrolytes: Cations + Sodium (Na ) + Potassium (K ) 2+ Magnesium (Mg ) 2+ Calcium (Ca ) Anions Chloride (Cl−) Bicarbonate (HCO3−) Phosphates (HPO42− and H2PO4−) Proteins PATIENT PREPARATION OSMOLARITY is the solute concentration maintained in all body fluids. It is 300 mOsm/L PRINCIPLES OF WATER AND SOLUTE BALANCE: One-third of IV fluids administered will stay in the intravascular space. Two-thirds will diffuse into the interstitial space. Colloids don’t pass freely through the vascular endothelium. The presence of colloids in the intravascular space draws water into the space creating osmotic or oncotic pressure. Some solute concentrations (Ca2+, K+) must be kept within a narrow range to maintain normal heart and muscle function. PATIENT PREPARATION FLUID ADMINISTRATION FOR ANESTHETIZED PATIENTS Anesthetic agents affect cardiopulmonary function by decreasing inotropy and heart rate. Many agents also cause vasodilation. This results in an overall decrease in cardiac output and hypotension. This affects oxygen delivery to the tissues IV fluids increase circulating blood volume and cardiac output PATIENT PREPARATION REVIEW OF IV FLUID TYPES: Crystalloids vs. Colloids CRYSTALLOIDS: the most common fluid type. Used for fluid replacement and maintenance. The 3 general categories of crystalloids are: Balanced electrolyte solutions (isotonic, polyionic, replacement solutions) Saline solutions Dextrose solutions PATIENT PREPARATION CRYSTALLOIDS: BALANCED ELECTROLYTE SOLUTIONS Contain a solute profile similar to the extracellular fluid since dehydration and many general diseases and peri-operative hemorrhage deplete the ECF first. This means higher concentrations of Na+ and ClExamples: Plasmalyte, Normosol, Lactated Ringer’s PATIENT PREPARATION CRYSTALLOIDS: SALINE SOLUTIONS Contain ONLY Na+ and Cl Examples: Normal Saline & hypertonic Saline Normal Saline (0.9%): used to flush body cavities, flush catheters, blood transfusions Hypertonic Saline (3%, 5%, 7%): very concentrated and quickly draws water into the intravascular space and supports blood pressure, but rapidly diffuses out into the interstitial space. Used for profound hemorrhage, shock, increased intracranial pressure PATIENT PREPARATION CRYSTALLOIDS: DEXTROSE SOLUTIONS (2.5%, 5%) Used in cases of hypoglycemia, neonatal, debilitated animals, hyperkalemia, patients receiving insulin Don’t use as the sole fluid. The sugar is rapidly metabolized to CO2 and water. The free water diffuses out into the interstitial space. PATIENT PREPARATION COLLOIDS: large molecules that do not readily leave the intravascular space These are helpful in maintaining blood volume and pressure Less side effects than hypertonic saline Rapidly pulls water into the intravascular space Examples: Plasma or blood, synthetic colloids, blood substitutes PATIENT PREPARATION COLLOIDS: PLASMA OR BLOOD Contains albumin, clotting factors, globulins Used in animals with acute blood loss, anemia, hypoproteinemia Expensive COLLOIDS: BLOOD SUBSTITUTES Used for acute hemorrhage and anemias Oxyglobin contains hemoglobin molecules of bovine origin similar to red blood cells that are able to carry oxygen. The benefit is that there is no cross-match required THIS PRODUCT IS NOT CURRENTLY AVAILABLE PATIENT PREPARATION COLLOIDS: SYNTHETIC COLLOIDS (Hetastarch, Dextran) More readily available than blood products Less expensive and longer shelf life than blood products Used in cases of shock, hypoproteinemia Usually administered IV at rate of 1020mL/kg/day; bolusedslowly over 15-60 minutes PATIENT PREPARATION ADVERSE EFFECTS OF FLUID ADMINISTRATION Volume overload – more likely in patients that are <5kg or those with cardiac or renal disease *reduce infusion rates Ocular/nasal discharge Chemosis Subcutaneous edema Increased lung sounds Increased respiratory rate Dyspnea Coughing, restlessness Hemodilution – dilution of the RBC’s and plasma proteins.
