Anesthesia levels and invoicing Isoflurane
At AERC, isoflurane minutes correlate to ASA established risk levels
and the result of how the anesthetic episode progressed within those
definitions (definitions taken from 84th WVC).
Level 1 - A normal, healthy pet
Level 2 - A pet with mild systemic disease which may or may not be associated with the surgical
complaint. (Example: obese, geriatric)
Level 3 - A pet with moderate systemic disease which may or not be associated with the
surgical complaint and which limits activity, but is not incapacitating. (Example:
compensated mitral insufficiency, collapsing trachea)
Level 4 - A pet with severe systemic disease that interferes with normal function and is
incapacitating and a constant threat to life. (Example: severe pneumothorax,
uncompensated heart failure, abdominal bleed from ruptured mass)
Level 5 - A pet that is moribund and requires immediate surgery or who is not expected to
survive 24 hours without surgery.
Definitions detailed
1. Level One - routine
a. ASA description: A normal, healthy pet
b. Pre-anesthetic assessment to anticipate estimated level: Patient has a medical or surgical
condition which necessitates anesthesia and
i. Is considered elective or minor
ii. Anesthetic risk is not complicated by age or preexisting disease.
c. Post-anesthetic assessment to determine invoiced level: No complications encountered
d. Examples:
i. Small wound in young animal
ii. Minor procedure < 15 minutes.
iii. Neuter/altering elective procedure
2. Level Two - stablized
a. ASA description: A pet with mild systemic disease which may or may not be associated with
the surgical complaint. (example: obese, geriatric)
b. Pre-anesthetic assessment to anticipate estimated level: Patient has a medical or surgical
condition which necessitates anesthesia and
i. Is not considered minor, or is minor in higher risk patient
ii. Is not considered urgent and could be postponed to another day if necessary
iii. Is not currently threatening the patient's life
c. Post-anesthetic assessment to determine invoiced level: Anesthetic complications are mild,
easily managed; may include brief periods of hypotension and/or apnea.
d. Examples:
i. Large or more complicated wound in stable patient
ii. History of recent trauma, crisis or blood loss, but is now stable
iii. Scheduled soft tissue or orthopedic surgical procedure
iv. Level 1 procedure older patient
v. Level 1 procedure in patient with mild systemic disease.
vi. Level 1 procedure that resulted in mild anesthetic complications.
3. Level Three – urgent care
a. ASA description: A pet with moderate systemic disease which may or not be associated with
the surgical complaint and which limits activity, but is not incapacitating. (example:
compensated mitral insufficiency, collapsing trachea)
b. Pre-anesthetic assessment to anticipate estimated level: Patient has a medical or surgical
condition which necessitates anesthesia and
i. Is considered urgent and should not be postponed.
ii. Is not currently threatening the patient's life.
iii. Patient’s health status and stablitiy are anticipated to complicate management of
anesthesia.
c. Post-anesthetic assessment to determine invoiced level: Anesthetic complications are
moderate, manageable and may include hypotension, apnea or arrhythmia. Any anesthesia
complemented by the administration of blood products and/or antiarrhthymics.
d. Examples:
i. Surgical procedure that wasn't pre-scheduled and/or shouldn't be postponed
ii. Level 1 procedure in patient with moderate systemic disease.
iii. Level 2 procedure in older patient or one with mild systemic disease.
iv. Level 2 procedure that resulted in moderate anesthetic complications
4. Level Four – critical care
a. ASA description: A pet with severe systemic disease that interferes with normal function
and is incapacitating and a constant threat to life. (example: severe pneumothorax,
uncompensated heart failure, abdominal bleed from ruptured mass)
b. Pre-anesthetic assessment to anticipate estimated level: Patient has a medical or surgical
condition which necessitates anesthesia and without such procedure, the patient's life is in
constant threat
c. Post-anesthetic assessment to determine invoiced level: Expected complictaions of
hypotension, apnea and/or arrhythmia; such complications are adequately managed.
Procedure results in improved stability for patient's constant threat to life. May require
second technician or doctor at times.
d. Examples:
i. Stablized GDV, hemoabdomen, septic patient.
ii. Any level patient where anesthesia became the constant threat to life.
iii. Any level procedure that resulted in anesthetic complications that required a
second technician or doctor at times.
5. Level Five – intensive care
a. ASA description: A pet that is moribund and requires immediate surgery or who is not
expected to survive 24 hours without surgery.
b. Pre-anesthetic assessment to anticipate estimated level: Patient has a medical or surgical
condition which necessitates anesthesia and
i. Wiithout such procedure, the patient's life is in constant threat to life
ii. Requires the constant need for additional team member(s) to maintain the
anesthesia
c. Post-anesthetic assessment to determine invoiced level: Pateint remained critical and/or
unstable during the nearly the entire anesthetic period OR required a second technician or
doctor involvment nearly the entire time. (Anesthetic minutes may be split between levels
4 & 5 when definition in question).
d. Examples:
i. Any procedure where the patient is critical and unstable despite preanthestic or
intra-anesthetic management.
ii. Any level procedure that resulted in anesthetic complications that required a
second technician or doctor nearly the entire time.