Patient Evaluation and Planning

Anesthetic protocol

Although terminology may differ, every anesthetic protocol follows a basic sequence:

  • Patient evaluation and planning
  • Premedication
  • Induction
  • Maintenance
  • Recovery

Each phase of anesthesia is comprised of a detailed set of critical activities. Veterinary practices focused on consistency and attention to detail should expect positive outcomes across the entire range of their anesthetic procedures.

Patient history review

Patient evaluation begins with a thorough review of the patient’s medical history.  The patient history review begins by updating the patient’s medical record during an interview with its owner.   Questions concerning changes in health status and behavior should be reviewed.  The owner should also be asked about the pet’s previous anesthetic episodes and past and current medication history, including heartworm prophylaxis and any supplements the pet is currently taking. Finally, it should be determined when the patient last had a meal.

Patient History Review

  • Health and behavior changes
  • Previous anesthesia
  • Medication ( inc. heartworm prophylaxis and supplements)
  • Time of last meal

Here are equipment guidelines to follow when preparing for an anesthetic procedure: 

CO2 absorbent

The CO2 absorbent should be checked and replaced according to its manufacturer’s specifications.   Note that patient size and varying metabolic rates affect the frequency with which the material needs to be replaced.  

Supply lines

Ensure supply lines are not blocked, not kinked and securely connected to their respective pieces of equipment.

Oxygen quantity and flow

Confirm sufficient oxygen is available and that flow meter is functioning properly.  Leak check the system prior to every procedure by closing the pop-off valve and blocking the patient connector.  Fill the system with oxygen to a pressure of 30-40 cm of water.  After turning off the oxygen flow, the system should remain pressurized for at least 10 seconds.

Waste gas scavenger

Verify an appropriate waste gas scavenging system is available and fully functional.

Monitoring equipment

Ensure all monitoring devices and leads are present and operational.  Know when monitors were last calibrated.

Warming and positioning devices

Check the adequacy of the supplemental warmth sources and the availability and functionality of required positioning devices.

The patient history review concludes with an explanation of the surgical and anesthetic procedure to be performed, including a risk assessment. Finally, obtain the client’s signature on the consent form.  

Physical Examination

Once the pet has been admitted, a physical examination is conducted, including vital signs, a baseline blood pressure and, if indicated, an ECG.

  • Vital signs
  • Baseline blood pressure
  • ECG, if indicated

Pre-anesthetic diagnostic tests

Results of all relevant pre-anesthetic diagnostic tests, including a biochemistry panel, complete blood count, and urinalysis and others, as indicated, should be reviewed and recorded in the patient history.  Based upon the history and physical examination, diagnostic imaging and may also be indicated.
Considering the factors found in the patient history review, physical examination and pre-anesthetic diagnostics, the veterinarian should note the patient’s ASA health status as a factor in her overall risk assessment for the procedure.

Pre-anesthesia Diagnostic Tests

  • Biochemistry panel
  • Complete blood count
  • Urinalysis


Documentation of the anesthetic event should begin simultaneously with the patient history review and chronicle the entire procedure through recovery.  Vital signs, peri-anesthetic events and interventions including medications and dosages, routes and time of administration are recorded.  Trained staff should record patient parameters at 5 to 10 minute intervals, more frequently if abnormal trends or unexpected events occur.

Documentation requirements

  • Timing: pre-anesthesia through recovery
  • All events, interventions
  • Medication:  doses, how/when administered
  • Frequency:  every 5 to 10 minutes

Equipment and medications pre-check

To complete patient evaluation and planning activities, ensure all equipment required for the procedure is accessible and in working order.  All required drugs and medications should be available in sufficient quantities and in date.  These activities can be performed prior to admission of the patient.  

Emergency medications should be available and their dose rates known and or displayed on a visible emergency chart.  It is important to pre-emptively calculate emergency drug doses for the patient being anesthetized.  Make sure all participating staff are current with procedures for cardiopulmonary cerebral resuscitation.