Lecture 23: Anesthetic Complications (Exam 3) Flashcards
When do anesthesia related deaths occur
- W/in 48 H in small animals
- Up to 7 days in horses
- Dogs, cats, & rabbits - 50% post op occur w/in 3 h of the end of ax
- Horses - 92% of complications occur in recovery & are neuromuscular or respiratory in nature
What kind of complications can occur during the peri ax period
- Common
- Uncommon
- Complications due to sx or dx procedure
- Human error or px idiosyncratic rxn
List the common complications during the peri ax period
- Hypoventilation
- Hypotension
- Hypothermia
- Hypoxemia
List the uncommon complications that can occur peri ax
- Metabolic
- Neuromuscular
- Post ax cortical blindness
What are some CV complications
- Hypotension - MAP < 60 mmHg
- Hypertension - MAP > 150 mmHg
- Hypovolemia due to hemorrhage
- Cardiac arrest
Describe arrhythmias as a CV complication
- Consider tx if BP is affected
- Look for underlying cause
What is in the decision tree for hypotension
- Recognize hypotension
- Check depth of ax & other causes
- Assess HR (determine if anticholinergic warranted)
- Consider IVF bolus up to 2 times (safe to give hourly rate over 15 min)
- Consider colloidal support (can include a transfusion of blood products)
- Discontinue ax as soon as possible
What are the two most common respiratory complications
- Hypoventilation
- Hypoxemia
T/F: Always be prepared @ induction to encounter issues w/ intubation
True
What is hypoventilation
ETCO2 > 55 mmHg
What can cause hypoventilation
- Anesthetic drugs
- &/or excessive anesthetic depth
- Pre existing co morbidities
- Possible equipment probs
- Decrease in respiratory rate
- Decrease in tidal vol
- Increase in metabolic rate
- Hyperthermia
What can hypoventilation lead to
- Respiratory acidosis
- Hypooxemia
- Increased intracranial pressure
What is the tx for hypoventilation
- Check depth & adjust
- Provide IPPV
- Change position of px
- Check equipment
Describe hypoxemia
- Unlikely if intubated & on 100% O2
- Can quickly become life threatening
- Can be hypoxemic & not show cyanosis
SPO2 of 95% = PaO2 of what
80 mmHg
SPO2 of 90% = PaO2 of what
60 mmHg
What is the tx of hypoxemia
- Check O2 glow rate for adequacy
- Check placement of ETT
- Check ax machine & SpO2 probe
- Give IPPV
- Consider adding PEEP
- Assess perfusion & support cardiac output
- Change position to sternal & discontinue ax if no improvement w/ other interventions
What are the causes of hypoxemia
- Hypoventilation
- V/Q mismatch
- Decreased FiO2
- Right to left shunt
- Diffusion impairment
Slide 19
Describe malignant hyperthermia
- Rare but life threatening phenomena
- May be inherited
- Reported in pigs, dogs (greyhounds), horses, & cats
Describe gastro esophageal reflux during gen ax
- Occurs when gastric contents pass into the esophagus
- Can be clear or brown fluid coming from the nose or mouth
- 50 to 60% of dogs may experience it
- 33% incidence rate in cats
- Can lead to esophagitis, esophageal stricture formation, or aspiration pneumonia
What are risk factors for GER
- Late stage preg
- Abdominal & ortho sx
- Expected in endoscopy
- Length of pre op fasting time & type of food
- Recumbency & changes in body position during ax
- Ax drug protocol
- Breed
- Pre existing condition
- Prolonged duration of ax
- Older dogs
What is tx for GER
- Be sure ETT cuff has a good seal (use pH strip to measure pH)
- Esophagus should be suctioned & lavaged w/ warm water & bicarbonate
- Sucralfate & H2 receptor antagonist
- Admin metoclopramide by bolus @ musch higher doses than commonly used reduces the incidence
- Oral omeprazole to reduce GER
- Maropitant will not prevent GER
What are some metabolic complications seen w/ gen ax
- Hypoglycemia or hyperglycemia
- A/B disturbance
- Electrolyte imbalance
When should hyperkalemia be txed
Before ax
What drug doesn’t lower K+
Calcium gluconate
Which drug promotes the release of insulin & the uptake of K+ into the cells
Dextrose 50%
Which drug dilutes the high serum of K+
0.9% NaCl (or another isotonic crystalloid)
What drug shift K+ into the cells
Reg insulin
What drug alkalinizines the blood by promoting K+ influx intracellularly & is only used in severe hyperkalemia
Sodium bicarbonate
Describe myopathy
Caused by ischemic muscle damage due to prolonged compression or inadequate padding &/or prolonged hypotension leading to under perfusion of muscles
Describe neuropathy
Caused by stretching, compression, ischemia, metabolic derangement, & surgical resection
What are the best tx for myopathy & neuropathy
- Prevention is better by paying attention to adeq padding & positioning of limbs
- Decrease ax
- Promptly treat hypotension
- IVF for diuresis, analgesics, ant inflammatory drugs, sedatives, & vasodilators
- Rehabilitation therapy may be beneficial
Describe blindness after ax in cats
- Seen after dental cleanings
- Due to use of mouth gas leading to cerebral ischemia (maxillary artery blood flow compromised)
- Neuro deficit may resolve in some px
- Could also happen due to sever hypotension &/or CPA
What are the signs of dysphoria recovery (Rough recovery)
- Vocalization
- Panting
- Restlessness
- Urination/defecation
- Salivation
- Thrashing, agitation, & hyper excitable are sx of emergence delirium
Describe dysphoria in recovery
- Seen w/in a short time after extubation
- Distinguish from pain
- Several causes of dysphoria
- Keep safety of px & personnel in mind
- Treat underlying prob & admin drug
What are tx for dysphoria in recovery
- Dexmedetomididine is most commonly used
- Acepromazine
- If benzodiazepine is suspected as the cause of dysphoria then consider flumazenil
- If severe consider propofol to reset recovery
- Consider naloxone if opioid induced dysphoria is suspected
List examples of preventable complications
- Human error
- Drugs
- Equipment malfunction
What causes tracheal tears in cats
- Over inflation of ETT cuff
- Turning the px while connected to breathing system
- Stylet puncture
- Extubation w/ cuff inflated
What are clinical sx of tracheal tears in cats
- SubQ emphysema
- Dyspnea
- Respiratory stridor
- Pneumomediastinum +/- pneumothorax
- Blood @ exubation
- may stop eating
- Cough
- Fever
What are some other possible complications
- Swollen feet &/or joint pain from being tied too tightly on the sx table
- Corneal ulcers
- Over admin of IVF
- Epidural need or local ax being placed directly in the nerve
What can be px reactions
- Anaphylatic & anaphylactoid rxn
- Anaphylactoid doesn’t req exposure to antigen & is more common
What are pharmacogenetic diffs
Genetic variablilty that determines an indiv response to drugs
What are the ax concerns of bracycephalic obstructive airway syndrome (BOAS)
- Smaller ETTS are more challenging for intubation
- Preoxygenate
- Use antiemetics b/c of concern for regurgitation/reflux
- Consider anticholinergics b/c of high vagal tone
- Protect bulging eyes
- Careful drug selection & titration of drug doses
- Injectable steroid for airway inflammation
- Careful monitoring in recovery
