Basic - General Anesthesia Flashcards
Read the 11 non-reassuring findings from ASA as predictors of difficult airway
- Long incisors
- Prominent overbite
- Cannot bring mandibular incisors anterior to maxillary incisors
- < 3cm inter-incisor distance
- Uvula not visible when tongue protruded
- High arched or narrow palate
- Mandibular space stiff or occupied by mass
- < 3 ordinary finger breadth TM distance
- Short neck length
- Thick neck
- Decreased extension or flexion of neck
*Decaying teeth is NOT a predictor
The liver receives ___% of total cardiac output
30%
- 3/4 by portal vein
- 1/4 by hepatic artery
_____ cells and specialized pathways detoxify substances, rendering them into harmless compounds. This process is the primary reason why ______ metabolism is effective.
Kupffer cells
First-pass
Liver synthesizes all of the procoagulants EXCEPT ____
Factors III, IV, and VIII
*overlaps with vit K dependent proteins 1972, giving vit K will differentiate if it is a deficiency in Vit K or hepatic procoagulants
Factor VIII is produced in ____
endothelial cells and bone marrow
Vit K dependent proteins are ______
Factors II, VII, IX, X
1972
*giving vit K will differentiate if pts with prolonged PT has a deficiency in Vit K or hepatic procoagulants
(ALT/AST) is the main cytoplasmic liver enzyme
ALT
*AST can be found in other body tissues
What can low albumin indicate?
- Chronic liver injury
- Renal loss
- Inc albumin catabolism
- Expansion plasma volume
- Maldistribution
Laryngospasm is a reflex response that involves the ADDuction of the ______, with motor innervation by the recurrent laryngeal n.
true and false vocal cords.
Individual risk factors of post op cognitive dysfunction
- Adv age
- Lower education level
- H.o Previous CVA with NO residual impairment
*Independent of type of surgery. ie. NOT cardiac sx
Anyone with a MI without intervention should wait ____ days before elective sx
60 days
Emergent vs Urgent surgery
Emergent: Life or limb is threatened if not in OR w/in 6 hours
Urgent surgery: Life or limb if not w/in 24 hrs
After an MI, Pts should wait ___ days after balloon angioplasty before elective surgery
14 days
2 antidotes for extravasation
- Hyaluronidase
- pediatric, TPN - Phentolamine
- alpha blocker -> vasodilates
How to administer phentolamine if phenylephrine extravasated?
Dilute 5 mg of phentolamine to 0.5mg/mL, then inject 1 mL increments into area surrounding extravasation site
Elevate limb
After fentanyl, which med is the most commonly abused opioid amongst anesthesiologist?
Sufentanil > Meperidine > Morphine > oral drugs
Inhaled anesthetic induction techniques are (improved/worsened) by benzos and (improved/worsened) by opioid
improved
worsened
Stage II excitation is (increased/decreased) with masked induction with sevoflurane
decreased
ASA 4 vs 5?
4: severe systemic disease, constant threat to life
- Recent < 3 mo TIA or MI
- ESRD NOT on regular dialysis
5: Moribund pt not expected to survive w/o operation
- Massive trauma
- ICH w/ mass effect
Severe aortic stenosis:
Valve area:
Transvalvular pressure gradient:
Valve area: < 0.8 cm^2
Transvalvular pressure gradient: > 50 mmHg
Where do you want to keep HR in pts with AR?
> 80bpm to decrease diastolic time and decrease time for regurgitation
Factor VII has a the shortest half life of the vit K dep factors, it has a half life of __, and can serve as an early measure of hepatic dysfunction by measuring ____
6 hours
PT/INR
Platelets are produced in the _____, and can be sequestered in the ____ secondary to portal hypertension
bone marrow
spleen
Factor VIII is produced by _______ (4). It is generally bound to vWF in blood.
- Vascular endothelium
- Renal tubular and glomerular cells
- Megakaryocytes
- Hepatic sinusoidal cells
Hemophilia A is d/t a defect in ____
genes for factor VIII
Neostigmine ____ mg/kg can be administered to reverse succinylcholine when a phase II block is present.
- 03 mg/kg
* neostigmine during a phase I block is ineffective, since postjunctional membrane remains in state of sustained depolarization, that is completely unresponsive to ACh.
Prolonged neuromuscular blockade can occur in pts with abnormal _____. std intubating dose produces depolarizing phase I block ~ 10 min.
But impaired metabolism of succinylcholine can lead to _____.
plasma cholinesterase
Prolonged phase I block that can progress to nondepolarizing phase II block (several hours)
Progression from a phase I to a phase II block means the postjunctional membrane has ______, though it is desensitized
Become repolarized
During a phase II block, neostigmine can reverse succinylcholine how?
it inhibits acetylcholinesterase ->
higher ACh [ ] in the NMJ
*but it also inhibits plasma cholinesterase which is responsible for succinylcholine metabolism, so dose needs to be low
After an MI, pts should wait __ days after a balloon angioplasty, ___ days after a bare metal stent, ___ days if no coronary intervention, and ___ days after a drug eluting stent for elective noncardiac sx
14
30
60
180
The oxygen affinity for hemoglobin is (higher/lower) in children/infants than adults. making their P50 (higher/lower)
Lower oxygen affinity for hgb
Higher P50
*P50 is the partial pressure of O2 when oxygen sat (SaO2) is 50%
The oxygen affinity for hemoglobin is (higher/lower) in newborns than adults. making their P50 (higher/lower)
very much higher
very much lower P50
When the oxyhemoglobin dissociation curve shifts to the Left, the P50 will (increase/decrease)
decrease
- P50 is the partial pressure of O2 when oxygen sat (SaO2) is 50%
- neonates have very low P50 d/t hemoglobin F
neonates have very low P50 d/t _____
hemoglobin F
- useful for oxygen transfer from maternal blood to the fetus
P50 is the lowest in ____, and highest in _____
newborns
children > 12 mo old
P50 increases, when the oxyhemoglobin dissociation curve shifts to the right.
What causes a RIGHT shift?
(Right) RIse in:
2,3 DPG
H+
Temp
and acidosis
P50 decreases, when the oxyhemoglobin dissociation curve shifts to the left.
What causes a LEFT shift?
(Left) Lowered:
Temp
CO2
2,3 DPG
and Alkalosis
LMAs are associated with which nerve palsy?
- Lingual nerve
- tongue numbness, no taste - Recurrent laryngeal
- vocal cord palsy - Hypoglossal
- tongue edema, diff with phonation
*Higher risk with N2O use
Type of surgery with the highest risk of exacerbating liver disease
Cardiothoracic surgery
____ accurately predicts perioperative mortality in pts with cirrhosis
MELD scoring system
_____ is the most common postop peripheral neuropathy.
______ can be used to evaluate for motor and sensory deficits
ulnar nerve injury
Nerve conduction studies
Electromyograms tell you what?
Exact location of injury in the setting of motor deficits
Timing of injury
DOUBLING the distance from radiation sources, decrease exposure by what factor?
4
(exposure is 1/4 of the original)
Intensity = Source / Radius ^2
Recommended occupational exposure to radiation / year
< 5000 mrem /yr
Each CXR is 10 mrem
CT scan is 5000 mrem
______ flow is reduced when there is systemic hypotension or cardiac output is decreased.
_____ flow is autoregulated and can compensate if the above drops.
Portal venous blood flow
Hepatic arterial blood flow
Neck circumference > __cm predicts increased incidence of OSA and difficulty with mask ventilation
60 cm
How to calculate BMI?
weight kg / height in meters ^2
Methgb (Fe3+ feric, icky) is unable to bind new O2, and the oxygen dissociation curve is shifted to the _____
left.
- PREVENTS release of O2 into tissues
- HIGHER affinity to O2
Ischemic optic neuropathy presentation
painless sudden vision loss following long spine surgeries in prone position
Respiratory effects of laparoscopic surgery
- lung compliance
- V/Q
- Inspiratory pressures
- Partial pressure CO2
- blood pH
- Decreased lung compliance
- Increased V/Q mismatch
- Increased inspiratory pressures
- Increased partial pressure of CO2
- Decreased blood pH
Pneumothorax presentation in GA
- Desaturation
- Increased Airway pressure
- Decreased breath sounds
Lethal dose of CO2 for obstructive embolism?
5x that of air bc of diffusibility of CO2
Subcutaneous emphysema presentation in GA
- Swelling or crepitus
- no change in pulse ox
- no change in airway pressure
Pneumoperitoneum is typically created in laparoscopic surgeries. What do you expect happens to ETCO2?
CO2 will be absorbed and equilibrate with CO2 in blood
- After 15-30 min it plateaus
In laparoscopic surgeries, If pts have a sudden increase in ETCO2 after the 15-30 min plateau period, what conditions do you suspect?
- Subcutaneous emphysema
- Early pneumothorax
- MH
Accidental endobronchial intubation would SLOW the relative rate of induction of which volatile anesthetic?
Desflurane > sevo > iso
- one lung ventilation creates a R-> L pulmonary shunt, which has greatest effect on less soluble inhalational anesthetics
One lung ventilation creates a R-> L pulmonary shunt, which has greatest effect on (more/less) soluble inhalational anesthetics
Less
- ie: desflurane, an insoluble agent
The faster the alveolar fraction (FA) of inhaled agent approaches the fraction of inspired (FI) agent, the (faster/slower) the agent will reach equilibrium.
Why?
faster
- the anesthetic partial pressures of the alveolus, blood, and CNS become equal
Insoluble agents like desflurane and nitrous oxide have (higher / lower) blood: gas partition coefficient
low
- partial pressure quickly builds in the alveoli
*The faster the alveolar fraction (FA) of inhaled agent approaches the fraction of inspired (FI) agent, the (faster) the agent will reach equilibrium.
More soluble agents like halothane and isoflurane will diffuse across the alveoli and into alveolar capillary bed more readily, thereby INCREASING the time needed to reach this equilibrium.
- What equilibrium is this referring to?
- the anesthetic partial pressures of the alveolus, blood, and CNS become equal
More soluble agents like halothane and isoflurane have (higher / lower) blood: gas partition coefficient
higher
What should you use to treat PONV if dexamethasone and zofran does not work?
Droperidol 0,625 mg IV
- dopamine 2 receptor antagonist
Vomiting center is stimulated by which areas?
- Chemotactic trigger zone in medulla
- GI tract
- Pharynx
- VIsual centers
- Mediastinum