Anesthesia & Disease Flashcards
What is the ASA status of a patient with mild mitral valve insufficiency that is asymptomatic?
ASA II
What is the ASA status of a patient with mitral valve insufficiency in addition to well-managed diabetes mellitus and hyperadrenocorticism?
ASA III (multiple systemic diseases)
Patients with low-grade second degree AV block may be able to be anesthetized with relative safety if they respond well to what?
Vagolytic agents, such as atropine and glycopyrrolate
What is your pre-med plan for a patient with CV irregularities?
- Benzos + opioids - although avoid opioids in an animal with a conduction abnormality and requires pacemaker placement
- Avoid alpha2s except for potentially in cats w/ HCM
- Alfaxalone - good choice for small animals w/ cardiac dz (esp cats)
What are 3 inhalant-induced cardiac changes?
- Decr contractility
- Decr cardiac output
- Hypotension
Describe features of HCM
- Poor diastolic function
- Myocardial ischemia esp. w/ exertion
- Arrhythmias and clots
- Cardiac murmur and possible outflow tract obstruction
- Thickening of ventricular free wall & septum
- Inability of coronary circulation to supply O2 to myocardium
- Stretching and distortion of AV valves
What are 4 clinical effects of HCM on the heart?
- Elevated end-diastolic pressures
- Incr sympathetic tone
- Tachycardia and incr contractility
- Low systemic pressures that lower resistance thru LVOT obstruction
What drug should you NOT ever give to a cat with HCM?
Ketamine! Incr heart rate and causes myocardial ischemia
What things should you keep in mind when preparing a cat with HCM for anesthesia induction?
- Minimize stress on myocardium
- Max O2 delivery to myocardium
- Max diastolic function
- Prevent fluid overload
- Prevent LV outflow obstruction
HCM Pre-Op
- Minimize stress and provide analgesia
- Treat any possible hypovolemia or dehydration pre-op
- Drugs:
- Opioids - provide analgesia w/ min CV effects
- Benzos - anxiolytics w/ min CV effects
- Alfaxalone - added sedation for aggressive cats (can give IM)
- Dexmed - reduces severity of LVOT obstruction
HCM Intra-Op Protocol
- Preoxygenate with minimal stress
- Give etomidate (min CV effects)
- Conservative fluid tx
- Minimize inhalant MAC
- Give phenylephrine
*NO KETAMINE OR DOPAMINE
What is the main anesthetic goal of degenerative valve disease and how do we do this?
- Promote forward blood flow and minimize regurgitation into atria
- Optimize CO
- Incr Preload, decr afterload
- Incr HR
- Incr contractility
DVD Pre-Op Protocol
- Minimize stress and provide analgesia
- Tx any possible hypovolemia or dehydration pre-op
- Drugs:
- Opioids - provides analgesia w/ min CV effects
- Benzos - anxiolytics w/ min CV effects
- Anticholinergic - incr HR and CO
- Ace - decr SVR
*NO DEXMED
DVD Intra-Op Protocol
- Preoxygenate with minimal stress
- Conservative fluidity therapy
- Minimize inhalant MAC
- Drugs: Etomidate, Ketamine, Dobutamine, Dopamine
*NO PHENYLEPHRINE
What should be your general considerations for anesthesia when dealing with generalized heart disease?
- Preoxygenate and monitor oxygenation
- Conservative fluid therapy (2-3 ml/kg/hr)
- Monitor BP and ECG carefully, tx underlying arrhythmias
- Use lowest possible amt of inhalant - consider opioid/lidocaine CRIs
Heart Disease Post-Op Protocol
- Continue monitoring and tx for arrhythmias
- Correct hypothermia
- Tx any lingering hypovolemia/hypotension
- Provide adequate analgesia
What are some clinical effects of liver disease on anesthetic drugs?
- Prolonged and more profound drug effect
- More available free drug and decr oncotic support
- Incr likelihood of intra-op bleeding
- Incr drug sensitivity
- Hypoglycemia
What are you anesthetic goals when dealing with a patient with liver disease?
- Avoid excessive drug doses
- favor reversible drugs that promote liver blood flow
- compensate for low albumin, glucose, clotting factors
What are some anesthetic consideration you should have for patients with liver disease perioperatively?
- Getting MDB, ammonia, BG, PT/aPTT
- Maintain normal BP and body temp
- Start dosing low
- Drugs:
- Remifentanil - not metabolized by liver (esterases)
- Isoflurane - favors liver blood flow
- Propofol - drug of choice - some extra hepatic metabolism
- avoid drugs with high protein biding and are non-reversible!
What is our main concern when anesthetizing patients with neurological disease?
Elevated ICP
What principle states that the brain and other structures are in a fixed space?
Monroe-Kellie Principle
Cerebral perfusion pressure is dictated by what two factors?
Mean arterial pressure and intracranial pressure
CPP = MAP - ICP
What is the physiological process of ICP increase causing cerebral ischemia?
Incr in ICP > decr in CPP > decr in CBF > incr in ischemia > incr in edema and tissue pressure > incr in ICP
Elevated ICP: Anesthetic Considerations
- Maintain BP to prevent worsening cerebral ischemia
- Permissive hypothermia: lower cerebral metabolic rate
- Smooth intubation: avoid coughing/vomiting
- Maintain Eucapnia: ETCO2 = 30-35 mmHg
Why is it really important to maintain normal ventilation for patients with elevated ICP?
To maintain eucapnia (ETCO2 = 30-35 mmHg) to prevent excess blood flow to the brain to try and compensate for changes in CO2
What are some anesthetic considerations for patients with elevated ICP?
Maintain normal BG - high BG > worse prognosis
Elevate head SLIGHTLY - avoid jugular compression
Tx for seizures - expect prolonged recoveries
What is your drug protocol for patients with elevated ICP?
- Midazolam - benzo
- maropitant - prevent emesis
- mannitol - reduce cerebral edema
- propofol - min effects on ICP, can be CRI
* avoid inhalants
What is the biggest thing you should keep in mind when anesthetizing a patient with chronic renal insufficiency?
Should be normovolemic with electrolytes corrected BEFORE anesthesia! Also get base BP
What are the effects of chronic renal insufficiency on pharmacokinetics?
- Hypoproteinemia - incr in portion of available free drug in highly-bound drugs
- Decr renal elimination - prolonged effects of drugs and metabolites excreted primarily by kidneys
- Azotemia alters BBB permeability - more profound drug effect
What are your anesthetic goals for patients with CRI?
- Max renal blood flow:
- Maintain MAP > 60mmHg
- use inotropes to incr CO
- Aggressive fluid tx
- Min use of inhalants w/ balanced technique
- Use reversible drugs w/ min CV effects - opioids and benzos
When is the most dangerous time for anesthetizing a patient with respiratory disease?
Induction and recovery
What are some general considerations to have when anesthetizing a patient with respiratory disease?
- Minimize stress
- Oxygen support
- Sedation: min resp depression (ace, butorphanol)
- Quickly control airway and ventilate
- Be prepared with alpha2s and antiemetics
What general considerations should you have in recovering a patient with resp disease?
- Continue O2 support
- Monitor oxygenation
- Drain chest tube
- Place in sternal recumbency
- Suction oropharynx/esophagus
- Be prepared to intubate!
What things should you keep in mind when treating a patient with diaphragmatic hernias?
- Elevate head above body
- Acute dz: ventilate aggressively
- Chronic dz: conservative ventilation
- Consider maneuvers to recruits collapsed alveoli:
- PEEP valve, recruitment maneuvers
How can the pathology of organ systems affect anesthesia?
- Alter drug pharmacokinetics (delayed ADME)
- Alter drug pharmacodynamics (incr toxicity, alter potency, change effects)
- Little reserve capacity to respond to anesthetic challenge
- Alter normal physiology
- Alter anesthetic management
- Alter fluid requirements
