Definitions/General Overview Flashcards
What is general anesthesia?
Reversible state of unconsciousness secondary to drug effects on the central nevous system
What are the goals of anesthesia
- Produce a state of
- Unconsciousness
- amnesia
- analgesia
- muscle relaxation
What is the approach to anesthetic management?
- Preoperative patient evaluation
- Preparation of equipment
- Anesthetic protocol
- Monitoring
- Recovery
- Post-anesthesia evaluation
What is part of the preoperative evaluation for anesthesia?
- Presenting complaint
- Hx:
- includes all current mediation
- pre-existing conditions unrelated to the current problem
- Physical examination
- Laboratory data and imaging results
- Patient problems by system
- Determine ASA status
What is ASA status?
- American Society of Anesthesiologists system for evaluating patient risk for anesthesia
- ASA status from I - V with E designation for Emergency
- Describes overall health
- Higher ASA status patients have a greater risk for anesthetic complications
- May require more intensive monitoring and management
- Does not reflect the procedure being performed
- Somewhat subjective
Describe ASA classification 1
normal healthy patient
Describe ASA class 2
mild systemic disease (obesity, geriatric, cranial cruciate rupture)
Describe ASA class 3
moderate systemic disease that limits activity but not incapacitating (dehydration, heart murmur, controlled diabetes, modest anemia)
Describe ASA class 5
Moribund patient that is not expected to survive w/ or w/out the procedure (life threatening trauma, septic peritonitis w/ septic shock)
Describe ASA class 4
Patient with severe systemic disease that is a constant threat to life (renal failure, pneumothorax, CHF
Describe ASA class E
added to any classification when an emergency procedure applies
What are the goals of the Preoperative evaluation?
- Identify any problems that may increase anesthetic risk and take any possible corrective measures
- ex: treatment of hypovolemia or dehydration PRIOR to anesthesia
- Determine if any concurrent medications should be withheld prior to anesthesia
- ex: angiotensin converting enzyme inhibitors may increase the risk for intraoperative hypotension
- Always a balance between how soon should we do the procedure and how stable is the patient
What supplies and equipment is needed for anesthesia?
- Supplies for IV catheterization
- Supplies for endotracheal intubation
- Drugs
- Anesthetic machine and breathing circuit
- Monitoring equipment
- Anesthetic record
ALL should be prepared and ready before patient is brought into the room
What are the goals of pre-anesthetic medication?
- Calm the patient and aid in restraint
- Decrease doses of anesthetic induction drugs and agents used to maintain anesthesia
- decrease any dose dependent effects of the drugs used to maintain anesthesia
- Analgesia
- Minimize undesired effects of anesthetics such as:
- nausea
- Bradycardia
- Muscle rigidity
What is anesthetic induction?
- Induce a state of general anesthesia
- Intravenous anesthetic agents used for induction
- Propofol
- Ketamine
- Ketofol
- Alfaxalone
- Etomidate
- Mask or chamber induction with an inhalant anesthetic is far less common
- fractious cats
- completion of induction after IV opioids
- Facilitates endotracheal intubation
What are the andvatages of endotraceal intubation?
- Airway protection
- facilitates positive pressure ventilation
- facilitates administration of inhalation anesthetic
What equipment is needed for endotracheal intubation?
- Laryngoscope
- Endotracheal tube
- Lubricant
- Endotracheal tube tie to secure the tube
- Lidocaine spray for some species (cats, small ruminants, pigs)
- Guide tube if difficult intubation anticipated
How is Anesthesia maintained?
- Inhalant anesthetic most common
- isoflurane
- sevoflurane
- Total intravenous anesthesia
- propofol
- alfaxalone
- Ketamine
- generally in conjunction with other drugs such as alpha-2 agonist or a benzodiazepine
- Other drugs that have been administered to the patient prior to induction may be repeated throughout a procedure
What does the anesthetist do to maintain anesthesia?
- Begin monitoring immediately
- Begin record keeping
- Observe and make changes to anesthetic delivery based on
- Anesthetic depth
- Response to noxious stimuli
- Respiratory and cardiovascular data
- Address any side effects or complication such as
- hypotension. arrythmias, changes in oxygenation, blood loss, hypoventilation
- Data recorded every 5 minutes
What are the observational parameters for anesthetic monitoring?
- Palpebral reflex
- Corneal reflex
- Swallow reflex
- eye position
- jaw tone
- muscle tone
- movement
What are the objective measurements for anesthetic monitoring?
- Heart rate
- blood pressure
- respiratory rate
- temperature
- end-tidal carbon dioxide
- End-tidal anesthetic agent
- Oxygen saturation of hemoglobin
- Laboratory test that might be indicated
- PCV, TP
- Arterial blood gas
- Glucose
When should a patient be extubated?
- When the patient has a sufficient level of consciousness that can swallow and protect its airway
Why may patients need oxygenation during anesthesia recovery?
Residual drug effects can cause hypoventilation leading to hypoxemia when animal is breathing room air
What needs to be managed during anesthetic recovery?
- Oxygenation
- Pain management
- Management of dysphoria
