Page 191 - WSAVA2018
P. 191

A. da Cunha1
1Louisiana State University, Veterinary Clinical Sciences, Baton Rouge- LA, USA
Anderson Favaro da Cunha, DVM, MS, Dipl.ACVAA
Professor and Chief, Veterinary Anesthesia and Analgesia
Department of Veterinary Clinical Sciences
School of Veterinary Medicine, Louisiana State University Baton Rouge, Louisiana, USA
Objectives: Review anesthesia related mortality and morbidity facts with a special focus on how to lower the odds of a patient dying under general anesthesia.
Many studies have elucidated the anesthetic related mortality and morbidity. The most important studies ever published for dogs and cats describe the following mortality rate:
· Overall risk (ASA 1,2,3,4,5, combined)= 0.17% or 1 in 601
· Health dogs (ASA 1 and 2)= 0.05% or 1 in 1849
· Sick dogs (ASA 4 and 5)= 1.33% or 1 in 7 Cats:
· Overall risk (ASA 1,2,3,4,5, combined)= 0.24% or 1 in 419
· Health cats (ASA 1 and 2)= 0.11% or 1 in 895
· Sick cats (ASA 4 and 5)= 1.4% or 1 in 7
· Overall risk = 0.001 to 0.0025% = 1 every 100.000
- 250.000The explanation for the major difference between human and veterinary anesthesia-related complication rates are simple. Pre-op evaluation and vital signs monitoring in human medicine is signifi- cantly better. The more you know about your patient before the beginning of the anesthetic procedure, the more prepared you will be for a possible com- plication. With modern monitoring, you can identify life-threatening complications earlier and start target treatment sooner.
The next paragraphs will shine some light on factors that have been recognized as important factors that may INCREASE the odds of anesthetic-related death. In another words, those are the factors that should be avoided:
· Increased physical status increases the chances of having a complication under general anesthesia.
· The more seek the patient is the more complicated the anesthesia management will be and obviously, the mortality rate of those seek patients is expected to be higher
This classification system is considered subjective. Different anesthesiologists may classify the same patient differently. But that is all right. The ASA classification is not designed to be precise but is a tool used to classify a patient based on its physical status. It is used to help the anesthesiologist to see if there is a possibility to reduce the risk of anesthesia by improving the ASA status of the patient prior to be beginning of the anesthesia. There
is evidence that survival rates deteriorate, as the ASA status gets worse.
Factors to consider when assigning ASA status:
· Cardiac reserve – is it compromised? Will anesthesia drugs make it worse? Can it be better with drugs or fluids?
· Pulmonary – what is the drug effect on the pulmo- nary system? What type of ventilation/oxygenation is required prior to anesthesia induction? Will patient position on the table influence the ventilation status?
· Renal – is dehydration, azotemia or uremia present? Will drugs be eliminated by renal system?
· Neurologic – any signs of CNS depression, behavior change, seizures, elevated ICP, anisocoria, nystag- mus?
· Hepatic - is the hepatic function compromised? Liver enzymes, blood glucose, albumin, coagulation disorders?
· Endocrine – any clinical signs of diabetes, thyroid disease, Cushing’s, Addison’s diseases?
· Hematologic – is anemia present?
· Physical status is independent of the surgical proce-
Urgency of the procedure
· Emergency procedures are associated with higher risks of anesthesia related mortality rate.
· Age is not a disease but is considered a co-factor as- sociated with anesthesia-related mortality rate. Both neonatal and geriatric patients are considered high risk patients for anesthesia.
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· The American Society of Anesthesiologists (ASA) published a physical status classification that helps us to guide ourselves:
   Physical Status
   Possible examples
  Normal healthy patient
  Elective procedures, ovariohysterectomy, castra- tion, allergy test
 Patients with mild systemic disease
 Skin tumor removal, repair of fractures or hernias, cryptochirdectomy, localized infections, compensated cardiac disease, obesity, mild dehydration
   Patient with severe systemic disease
   Fever, anemia, dehydration, cachexia, moderate hypovolemia, kidney disease, C-section
 Patient with severe systemic disease that is a constant threat to life
 Uremia, toxemia, severe dehydration and hypox- emia, anemia, cardiac instability, emaciation, high fever, GDV, azotemia, caval syndrome
  Moribund patient not expected to survive 1 day with or without operation
  Extreme shock and dehydration, terminal malig- nancy or infection, or severe trauma, sepsis
   Any category can receive an emergency status

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