Anesthesia Flashcards
What drugs should be avoided in severe respiratory patients?
Alpha-2 -> Respiratory depression
Beta blockers -> don’t use with pneumothorax patients
Avoid high spinal epidurals
In a patient on a ventilator with pleuritis, what pressures should you not exceed?
Pressure should be less than or equal to 10cm H20
What are concerns of reintroducing negative pleural pressure too quickly with a patient that has chronic atelectasis?
Re-expansion pulmonary edema
What patients should be on a non-rebreathing system?
Tobias says <5kg; Lumb/Jones says <10kg (ideally 3-7kg)
What general steps occur when the CO2 absorbs in the rebreathing system?
Absorbent contains various concentrations of Ca(OH)2 and CO2 + hydroxides -> carbonic acid -> H2O + CaCO2
What is the flow rate formula for a rebreathing system?
10x BW (kg) ^0.75 = 3-6 mL/kg/min
What is the recommended flow rate for a non-rebreathing system?
3x patient’s minute volume (MV = RR x TV)
~200-300 mL/kg needed to prevent rebreathing
What are the phases of the waveform on end-tidal CO2 monitors?
0: fresh gas passes sensor
1: CO2 from lungs passes sensor, elevating waveform
2: Plateau once mixing of dead space gas
3: Waveform peaks during end of expiration
4: Inspiration draws fresh gas over sensor, waveform drops to baseline
Draw how an end tidal CO2 waveform would change in the following situations:
1. Hypoventilation
2. Hyperventilation
3. Rebreathing CO2
4. Leak in circuit
- Increase in height of plateau
- Decrease in height of plateau
- The waveform does not return to zero/baseline at inspiration
- “Sail” shaped end to waveform vs nice plateaus with sharp drop at inspiration
What nerve blocks are available for dental procedures?
Mental
Inferior alveolar
Infraorbital
Maxillary
What dose of bupivicaine do you use in dogs vs cats?
2.5mg/kg dog
1mg/kg cats
What induction agents can increase intraocular pressures?
Ketamine and propofol
What are the heat exchange mechanisms in anesthetized patients?
Evaporation= lungs/feet
Conductive = cold surfaces, water washing
Radiation = loss of infrared energy
What is the most effective method of warming anesthetized patients?
Forced warm air
Normal CVP with monometer?
With transducer?
0-8cm H2O
0-5mmHg
What are four methods of nonivasive cardiac output monitoring and describe how performed?
- Thermodilution (themometer tipped pulmonary catheter / inject saline at known temp -> AOC of temp change is CO)
- Lithium dilution (inject Li venous, aspirate from arterial)
- Pulse contour analysis (arterial BP waveform after calibration via Lithioum or thermo)
- Noninvasive CO (uses CO2 to estimate O2 consumption via Fick principle).
How does the pulseOx calculate SpO2?
What HCT level will cause changes in SpO2 on pulseOx?
What are common causes of inaccurate SpO2 readings?
Calculates by Hb absorbtion within the arterial pulsatile component of the path the light travels.
HCT <10%
Vasoconstriction/lowCO, hypothermia, pain, alpha-2 agonists
How does uremia make catheters problematic?
What drugs should be used with caution as pre-med/induction in renal dz patients?
What local block should be avoided?
What can be given to dogs with poor urine output to improve urine flow?
Uremia impairs platelet function.
- Alpha-2s increase urine output so don’t use in obstructions.
- ketamine is excreted unchanged in cat urine
Avoid epidurals because of the possibility of platelet dysfunction/hemorrhage
Mannitol, furosemide, dopamine to increase flow
When heart failure occurs, what 2 neurohormonal changes occur that affect anesthesia?
Body activates the RAAS -> fluid retention and hypervolemia; also upregulates the sympathetic NS
What are anesthetic monitoring changes seen with air embolus?
Sudden decrease in ETCO2, drop in BP and pulseOx, +/- audible “washing machine” murmur
What induction drug should be avoided in thyroid patients, especially hyperthyroid?
Ketamine because may have concurrent heart disease and because it can induce a thyroid storm
What 3 drugs can be given to patients with insulinomas while under anesthesia?
-Glucocorticoids (promote insulin resistance and gluconeogenesis)
-Glucagon to normalize BG 5-13mg/kg/min
- alpha-2s increase insulin resistance
What drugs should be available for emergency surgeries on the biliary tree?
Which opioids are best for premed of liver patients? Why?
Which induction agent is best for liver?
Anticholinergics because can have increased vagal tone
Morphine, hydromorphone, oxymorphone -> don’t need P450 for clearance and don’t accumulate in tissues
Propofol has extrahepatic sites for metabolism +/- ket/midaz
What is absorbtion atelectasis?
Alveolar collapse when O2 replaces N volume then is rapidly absorbed -> no more volume to hold open
What causes malignant hyperthermia?
What do you treat with?
Defect in ryanodine receptor (Ca++ release)
Dantrolene to decrease Ca release
What HCT level will cause changes on SpO2 on pulse oximeter?
<10% HCT
Put in order fastest to slowest change in body temperature over time:
- 3 blankets
- 1 blanket
airway heat/humidification
-circulating water blanket - forced air
Fast:
Forced air
3 blankets
circulating water mattress
one blanket
airway heat/humidity
Slow
Which gas does charcoal not scavenge?
N2O
With V/Q mismatch, do you see hypercapnia?
Not usually because CO2 has a high diffusion capacity
What is the difference between a Miller and a MacIntosh laryngoscope?
What drugs are helpful for anesthesia in a dog with DCM?
What drug may increase potential for arrhythmias under anesthesia?
Generally, for anetshesia in heart dz, what premeds should you pick?
Best induction agent?
One to avoid?
dobutamine (inotropic)
digoxin may increase arrhythmias
premeds:
- opioid + tranquilizer (neuroleptanalgesia) avoid ace if hypotensive, avoid alpha-2, avoid ketamine
Induction - etomidate best, propofol/alfax caution, ketamine contraindicated
How does warm weather affect vaporizer output?
What are the 2 ways of vaporizer output?
What are the three methods of vaporization?
Why does desflurane need a specific vaporizer?
increases output
bypass (measured flow / 2 separate flows) or flow-over/bubble through/direct injection
desflurane has a specific boiling point that it needs to be heated to in order to become gas
How much (in mmHg) does the doppler often underestimate in cats?
How does oscillometric BP work? What does it underestimate?
less than or equal to 25mmHg
returning bloodflow causes turbulence sensed as a pressure oscillation
- greatest oscillation = MAP
-abscence of oscillations = DAP
it underestimates SAP,DAP,MAP in dogs and SAP in cats
What are parameter changes with malignant hyperthermia?
Why is there muscle rigidity?
How do you treat malignant hyperthermia?
hypercarbia, hyperthermia, muscle rigidity, arrhythmias, death
Ryanodine receptor defect -> Ca release
Treat by d/c inhalants, IV dantrolene, convert to TIVA if need to stay under
What premed to avoid with adrenal disease?
Which induction to avoid?
acepromazine -> can cause alpha antagonism and complicate sympathetic tone management
alpha2 effects in pheos are unpredictable
etomidate - avoid in Addisons because supresses steroids
Which induction to avoid in septic patients?
Premeds to avoid with sepsis?
Which gas can be used with maintenance and fentanyl in sepsis?
Etomidate - these dogs often have corticosteroid deficiency from sepsis
alpha2 and acepromazine
N2O
List and describe the 5 ASA statuses
1= no systemic illness healthy
2= mild compensated systemic illness
3= mod->severe compensated illness
4= patient has disease that is constant threat to life
5= moribund patient not expected to survive 24hr with or without treatment
What is an SGAD?
Other name?
Benefits?
Supraglottic airway device (aka laryngeal masks)
good for rabbits, maybe you need less anesthetic
Where do you place the (+) and (-) electrodes on the peripheral nerve stimuator?
What is train of four analysis?
What must you not give until all four twitches return?
negative closer to body, positive distal to induce twitch
4 stimuli over 2 sec. Increased receptor blockage causes fade of the strength of contraction with decreased amplitude of twitch -> eventually no twitch
Do not give pharmacological reversal agent. Gotta wait for there to be a low enough level of NM blocker at junctions for this to be overcome by the increased acetylcholine
Which heart conditions should NOT be treated with lidocaine?
Those with third degree av block and those with ventricular escape rhythms
List examples of regional blocks
RUMM
Femoral/sciatic (or saphenous)
epidural
brachial plexus
paravertebral
Esmarsch (Bier block)
What are 5 causes of hypoxemia?
Which is most common?
Hypoventilation, R->L shunt, decreased inspired O2, diffusion impairment, V/Q mismatch
V/Q mismatch
What determines an ascending or descending ventilator bellows?
Ascending “stands” during expiration
Descending “hangs” during expiration
What is the contraindication for giving anticholinergics (atropine/glyco) to treat bradycardia caused by dexmed or other alpha2s?
Will result in increased cardiac work and severe hypertension
What drugs are recommended to have nearby for all neonatal anesthesia?
Which is the most important heart parameter to maintain in neonates?
Anticholinergics
HR - neonates have trouble increasing stroke volume
What volume do you use for a lumbosacral epidural?
For a thoracic + abdomen coverage?
If local epidural spreads to ganglia of sympathetic chain -> vasodilation -> how do you treat?
0.2mL/kg
0.3mL/kg for thoracic/abdomen
IV bolus phenylephrine or dopamine
What are some anesthetic machine/factors causing hypercapnia?
Expired/exhausted soda lime
Expiratory valve damaged
Fresh gas flow not high enough in a non-rebreathing circuit
Heart patients with stenotic lesions may benefit from what drugs?
anticholinergics
What is the Branham reflex?
reflexive drop in HR after ligation of a PDA due to abrupt increase in afterload / increased systolic BP
What are criteria for treating VPCs?
Vtach (>150), multiform, syncopal event/hypotension, R on T phenom, runs of VPC
What anesthetic drugs will impair the hypoxic pulmonary vasoconstriction compensatory mechanism?
Inhalant anesthetics
Why would ketamine be helpful in animals with allergic airway disease?
ketamine causes bronchodilation
What drug class should be added to premed for brachycephalics and why?
anticholinergics because brachys have increased vagal tone
What situation/patient dz would lead you to pick pressure-cycled ventilator over volume?
Pressure cycled is better for dogs with changing pulmonary compliance (severe airway disease) because a volume cycled would make pressures too high
What diastolic arterial pressure indicates poor coronary artery perfusion?
<40mmHg
What can be added to O2 to protect against fires from laser use?
Helium 70:30 with O2
What are the colors for the gas tanks?
O2
NO2
He
CO2
N
Room air?
O2 - green/white
NO2 - Blue
He - Brown
CO2 - Gray
N - Black
Room air - Yellow
What are the main anesthetic concerns with adrenal dz patients (cushings, addisons, pheo)?
Cushings = infection risk, hypovolemia (from polyuria), hypercoagulable/PTE
Addison’s -> hypovolemia/GI shock (avoid etomidate)
Pheo = tachycardia or bradycardia, arrhythmias, hypertension (alpha-blockers, +/- nitroprusside)
What analgesics should be used with caution in hyperthyroid patients?
avoid NSAIDs because these patients are at risk for renal dz
With diabetic patients, when do you give dextrose boluses?
Should patients be given their morning insulin?
When BG is <70, and then start 2.5% dextrose in fluids after bolus
no morning meal-> give 1/2 normal insulin dose
With laparoscopy, decreased renal blood flow is seen at ____cmH2O?
> 14cmH2O
Which drug is the one shown to adversley affect neonatal survival?
Xylazine
With anesthesia on cats with HCM, what are some physiology factors that affect protocol choices?
-poor preload so use Beta blockers/calcuim blockers to increase diastolic fill time
- systolic anterior motion of the anterior mitral valve leaflet compromises CO -> consider IVF
- caution with dobutamine as it increases the myocardial O2 demand via tachycardia and also decreases the diastolic fill time
