Pre-Anesthetic Workup

Pre-Anesthetic Workups

  • No universal guidelines for pre-A diagnostics

  • Some tests routinely done for animals undergoing anesthesia

  • Additional tests for certain categories of patients (geriatrics, sick ve elective, etc)

  • Age, history, and results of physical status

  • Financial and other considerations

  • If clients declines, waiver should be completed (acknowledge they understand the risk)


Common Tests

  • CBC:

    • Evaluation of blood cell numbers and morphology

    • Including:

      • PCV, TP, Hemoglobin, WBC count, RBC count, and platelet count

  • Urinalysis:

    • Provides info about the  urinary system and the kidneys

    • Kidneys are key in regulating:

      • Electrolyte and water balance, blood pressure, and elimination of anesthetic drugs

  • Blood Chemistries:

    • Wide variety available to assess circulating enzymes, electrolytes, proteins, and metabolites

    • Info about:

      • Organ health and function

  • Blood Coagulation Screening:

    • Evaluate the chemical and sometimes mechanical components of blood coagulation

    • Proper clotting is essential for surgical procedures

  • Electrocardiograms (EKG):

    • Records the electrical activity of the heart and assess heart rhythms

    • Anesthetic agents alter heart rate, cardiac output, and oxygen consumption - so any heart disease increases the risk for complications

  • Radiography:

    • Thoracic radiography may show signs of cardiac or pulmonary disease

    • Abdominal films warranted if trauma case or to rule out other conditions that may increase anesthetic risk


Physical Class Classifications

  • Created by the ASA (American Society of Anesthesiologists)

  • Assess overall patient health; assign to category 1-5 for healthy to moribund/not expected to survive surgery

    • 6th category = brain dead organ donor (not used in vet med)

    • Emergent patients should be marked with an E

  • Help gauge anesthetic risk

  • Not perfect system - use as a baseline for anesthetic planning

  • PS1 and PS2 - standard anesthetic protocol

  • PS3 and above - often required individually tailored protocol

Know the chart on powerpoint for the Exam


Selection of an Anesthetic Protocol

  • Veterinarian prescribes anesthetic drugs

  • Typically, they will create anesthetic protocols that are standing drug orders for patients

  • Modify for patient needs in accordance with veterinarian


Factors Involved with Selecting a Protocol

  • Facilities and equipment

  • Familiarity with agent

  • Nature of the procedure

  • Circumstances specific to procedure

  • Cost

  • Degree of urgency


Preinduction Care

  • Withholding food (fasting)

    • Complications can occur if patient is not properly fasted before anesthesia

    • Esophageal reflux: occurs as result of loss of lower esophageal sphincter tone (flow of stomach acid into esophagus due to patient positioning)

      • Can cause tissue damage

    • Vomiting - active expulsion of stomach contents (preceded by retching)

    • Regurgitation - passive process where stomach contents flow into esophagus and mouth

    • Pulmonary aspiration can occur after either vomiting or regurgitation when swallow reflex is decreased or absent

      • Can lead to  pneumonia, death

    • Fasting patients can help prevent this

    • Fasting times vary based on species

      • Dogs/cats/horses: 8-12 hours

      • Cattle: 24-48 hours

      • Small ruminants: 12-18 hours

    • Excludes: Neonates, Pediatric patients, and exotics

    • Regurgitation or vomiting can still occur even in fasted animals

      • Foam, bile, mucus

      • Protect with cuffed endotracheal tube

  • IV Catheterization: Reasons

    • Fluid administration - maintain blood volume, support BP!!!

    • IV access in case of emergency

    • Used for CRI

    • Vesicants - term for anesthetic agents that will damage tissues if given perivascularly

    • Ease of giving multiple drugs (IV fluids flush in between)