Veterinary Anesthesia Evaluation

Patient Evaluation and Preparation

• Learning Objectives:
  • Describe who, what, where, when, and why a thorough patient evaluation is needed before anesthesia.
  • Detail the preparation for veterinary patients undergoing anesthesia.
  • Outline the general anesthetic concerns for a patient prior to anesthesia.

Who Should Perform Pre-Anesthetic Evaluation?

• Ultimately, the veterinarian in charge of the patient is responsible.
• Situations involving registered technicians, rotations, or co-involvement of a surgeon and anesthesiologist should be considered.

What Exactly Is Part of Pre-Anesthetic Evaluation?

• Signalment: Species, breed, age, sex, and reproductive status are required.
• History: Include previous anesthesia events, current symptoms (severity & duration), medications, and vaccination status.
• Physical Examination (PE): Body weight (BW), body condition score (BCS).
• Blood and Urine Sampling: Essential for baseline data.
• Temperament/Mentality: Assess the patient's temperament and pain level.
• Advanced Diagnostics: ECG, blood pressure, radiographs, abdominal ultrasound (U/S), echocardiogram, endocrine testing, etc., if needed.

Routine ECG Screening

• Necessary for patients with cardiovascular disease (CV disease).
• Geriatric patients are a priority.
• Conditions that can lead to arrhythmias (e.g., hyperkalemia, splenomegaly, traumatic myocarditis)

Physical Exam Findings

• Temperature: Know the normal range for each species.
• Pulse: Rate, rhythm, and quality. Simultaneously auscultate for murmurs and palpate the pulse. Explain what the pulse reveals.
• Respiration: Describe the sounds heard, not just "normal limits" (WNL). Explain why the trachea should be palpated.
• Body Weight: Record in pounds (lbs) and kilograms (kg)
• MM/CRT (Moist mucous membrane/capillary refill time): Explain how this relates to hydration and hemodynamic status.

Physical Findings in Dehydration

• Different levels of dehydration correlate with specific clinical signs (loss of skin elasticity, sunken eyes, etc). Data from DiBartola's text is referenced.

Remainder of Physical Exam

• Assess the integument, lymph nodes (LN), gastrointestinal (GI) tract (palpate abdomen, listen for gut sounds), genitourinary tract, and central nervous system (CNS) and consider why these systems are crucial.

The “SOAP” & Anesthesia Request Form

• SOAP: Subjective, Objective, Assessment, Plan, and pertinent information about the patient from the owners
• Anesthesia Request form: Include species, weight, BCS, and physical examination data.

What Lab Work Should Be Done?

• Young Patients (under 5 years old) with no abnormal history: PCV/TS/Glucose/BUN ("Big 4" or "QATS").
• Older Patients & patients with a history of illness: CBC/chemistry profile/urinalysis ("minimum database"). Include consideration of infectious diseases.
• Additional testing: T4, ECG, blood pressure, thoracic radiographs, echocardiogram, blood gas analysis, coagulation profile, liver function tests, etc. - may be indicated based on individual patient needs

Where is the Pre-Anesthetic Evaluation Performed?

• Typically in the clinic, and also during farm visits.
• Locate a quiet space to allow for auscultation of heart and lungs.
• Consider the handling requirements for fractious, zoo, or wild animals.

When Should Pre-Anesthetic Evaluation Be Performed?

• Usually the day before or up to a week before a scheduled procedure. A shorter examination is performed on the day of anesthesia.
• If surgery is postponed, re-examine the patient closer to the date of surgery.
• Emergency cases require immediate evaluation.
• Consult with the owner on relevant case-specific details/questions.

Why Should a Pre-Anesthetic Evaluation Be Done on All Patients?

• Increases the likelihood of a safe anesthetic episode and a successful outcome.
• Assess the overall organ function and perioperative risk.
• Provides valuable information to the client and helps them make informed decisions.
• Documentation is crucial before sedation/anesthesia.

ASA Physical Status Scale

• Classification system to describe patients based on overall health and risk. Ranges from normal to critically ill.

What is the Physical Status?

• Presence/absence of disease; severity of pain if present; level of stress; overall organ system function.

When Should the ASA Physical Status Be Assigned?

• After the physical exam (PE) and lab work are complete and interpreted. Consider elective vs. urgent/emergent cases

Case Examples:

• Provide details of specific animals, their presenting concerns, exam findings, and ASA status. Several case examples are provided.

General Anesthetic Concerns

• The "4 H's": Hypotension, Hypoventilation, Hypothermia, and Hypoxemia.
• Other Considerations: Hemorrhage, pain management, recovery time, regurgitation, laryngeal spasms, difficult intubation, dysphoria, and heart complications (arrhythmias, myopathy, neuropathy).

Signed Consent

• Obtain signed consent or verbal confirmation by the owner/responsible party.

Suggested Reading Materials

• Handbook of Veterinary Anesthesia (5th ed), Chapter 2 (pages 12-21)
• AAHA Monitoring Guidelines for veterinary patient care (available on Canvas).

Other Considerations

• Patient preparation for procedure: Fasting guidelines and recommendations are included; hygiene. Correct dehydration and electrolyte imbalance; including consideration of anemia; use of preoperative antibiotics.
• Dosing drugs: factors to consider when determining drug dosages (breed, size, fat/muscle mass, obesity, condition, and age). Metabolic rate changes.
• Concurrent medications: Potential anesthetic implications for various medications like aminoglycosides, ACE inhibitors, etc.