ITE Gen Clin Sciences 2 Flashcards
Inheritance pattern of Malignant Hyperthermia
Autosomal dominant with variable penetrance
MH is a (heterogeneous/homogenous) disorder
heterogeneous
- more than 1 gene defect is responsible for expression of disease
Two receptors involved in MH
RYR1 gene - ryanodine receptor
VG calcium channel
In cardiac surgery, when is awareness/recall most likely?
During rewarming and departure from CPB.
- Anesthetic requirement is higher
- MAC > 0.7 can help
Benefits of double lumen tube > bronchial blocker
- More reliable lung isolation
2. selective lobar collapse
Benefits of bronchial blocker > double lumen tube
- Smaller
- better for pts with trachs or oral/neck sx
- children < 12 - Does not require Endotracheal tube exchange (like DLT)
Benefits of airway exchange catheter > gum elastic bougies?
- Ability to jet ventilate
2. ETCO2 monitoring
Why are diuretics (furosemide) d/c in preop period?
- Hypokalemia
- Blood loss/fluid shifts -> worsen hypokalemia
- Predispose to arrhythmias
*ACE-i and ARBs are also often stopped
What BP meds should NOT be stopped in periop period?
BB
CCB
alpha - 2 agonists (clonidine)
(Barium hydroxide / Soda lime) produces more carbon monoxide and more Compound A d/t decreased water content in the absorbents
Barium hydroxide
Soda lime is made of ____
80% calcium hydroxide
15% water
4% sodium hydroxide
Only medication preventing aspiration pneumonitis when given immediately prior to anesthesia
Sodium citrate
Medications used perioperatively for pts high risk of aspiration
- Sodium citrate
- immediately b4 - H2-blockers
- 1 - 2 hrs b4 - Metoclopramide
Anthrax treatment
Ciprofloxacin
or
Doxycycline
Anthrax clinical course
1-7 days incubation - asymptomatic
Nonspecific influenza-like sx
Gets better, but then gets worse again
- CP
- Cyanosis
- Dyspea
- Hemoptysis
- Necrotizing hemorrhagic mediastinitis
Drugs dosed on ideal body weight
Vecuronium
Rocuronium
Cisatracurium
Drugs dosed on total body weight
Succinylcholine
Propofol MAINTENANCE not induction (LWB)
Maximum lidocaine dosing
55mg/kg
When is LAST (neurologic decline and hemodynamic instability) most likely to occur perioperatively?
10-16 hours after a procedure when [ ] of local anesthetic peaks
Largest # of closed claims for death and brain damage?
- Cardiovascular events
- PE, Stroke, MI, Arrythmia - RESPIRATORY EVENTS
- inadequate ventilation
- esophageal intubation
- diff airway - Equipment issues
How does aspirin prevent clots?
permanently inactivates COX enzyme
- short half life 15 min
- long duration of action
What does inhibiting COX do?
conversion of arachidonic acid to prostaglandin
Prostaglandin -> Thromboxane A2, vital for platelet aggregation and vasoconstriction
Platelet life span is _____, and ____% of circulating platelets are replaced daily
5-10 days
20%
What does clopidogrel and prasugrel do?
Platelet receptor inhibitors
- platelet is inactivated for remainder of its lifespan
Pts who had a coronary cath with bare metal stents can stop taking dual antiplatelet therapy when if postponing surgery -> sig morbidity?
1 month
Pts who had a coronary cath with drug eluting stents can stop taking dual antiplatelet therapy when if postponing surgery -> sig morbidity?
3 mo after stent placement
- preferable 6 months
What is dual antiplatelet therapy?
Clopidogrel + ASA
_____ is primarily responsible for increased systemic vascular resistance and MAP during pneumoperitoneum (CO2 Insufflation) for laparoscopic surgery
Increased vasopressin release
- decreased RH filling
- Decreased renal/splanchnic blood flow -> RAAS system activated -> vasopressin response
- CO2 absorption -> sympathetic response
Absolute contraindications to electroconvulsive therapies?
- Pheochromocytoma
- Recent MI
- Recent CVA
- Recent intracranial sx
- Intracranial mass lesion
- Unstable cervical spine
*Cerebral blood flow increases 400% during ECT secondary to increased metabolic rate and BP -> increases ICP
Why does pulmonary edema result in pts with CHF?
Increased hydrostatic pressure and activation of RAAS
Maximum lidocaine dose with and without epinephrine
55 mg/kg max
7mg/kg with epi
Which one provides better intubating conditions during RSI, rocuronium or succinylcholine?
No difference
How is Roc and Suc dosed based on body weight?
Roc - IBW
Suc - TBW
How many working days are residents allowed to take off during their training?
60 days
(12 weeks)
- 4 weeks/year
+ 5 days for scientific meetings
Physiologic changes in CNS that makes geriatric population more sensitive to neuraxial anes?
- Smaller epidural space
- Less myelinated fibers in dorsal and ventral nerve roots
3, More permeability of dura - Less volume of CSF
The solubility of gases in the serum will (increase/decrease) as a pts temperature is decreased.
increase
*when pts temp drops, more gas remains dissolved in serum like CO2 and value is lower on ABG
In hypothermic pts, what type of metabolic derangement will you see?
Hypocapneic respiratory alkalosis
**when pts temp drops, more gas remains dissolved in serum like CO2 and value is lower on ABG
When do you use pH-stat vs Alpha stat?
pH-stat : Pediatrics
Alpha stat : Adult
A standard dose of succinylcholine (1-2mg/kg) will produce a (phase I / Phase II) block, which means _____
Phase I
- sustained depolarizing block
What antagonizes a phase I block, and what augments it?
Nondepolarizing NMB antagonizes it
Depolarizing blockers and cholinesterase inhibitors will augment the block
In Phase I vs Phase II block, Train of four ratio is typically ___
Phase I: > 0.7
Phase II: < 0.3
Pts with pseudocholinesterase deficiency will affect succinylcholine how?
May create a phase II block
- increase DOA by several hours
*Depolarizing blockers and cholinesterase inhibitors will augment the block
Equipment standards for surgical facilities and office practices (5)
- reliable oxygen source
- suction
- resuscitation equipment
- emergency meds
- back up power source
5 Standard monitors for GA
- ECG
- BP
- Pulse ox
- Ventilation (ETCO2)
- Body temp
Endotracheal intubation is contraindicated in laryngeal disruption or laryngotracheal separation. What should you do instead?
Wake surgical tracheostomy
Le Fort fractures
Le Fort I: roof of mouth and palate separated from face
Le Fort II: nose and palate sep from face
Le Fort III: entire face affected
What should you pay attention to regarding Le Fort II and III fractures?
II and III are assoc. w/ cribriform plate disruption
- presence of hemotympanum
- CSF rhinorrhea
- Racoon eyes
- mastoid ecchymosis (battle signed
Pts on antithrombotic or thrombolytic therapy for > __ days need to have platelet counts checked before neuraxial block or catheter removal
4 days
- pts at risk of HIT
Cholinesterase inhibitors (or anticholinesterases) affect nondepolarizing and depolarizing NMBs how? Why?
increase resistance to nondepolarizing MRs: ie: roc
- Anticholinesterase inhibit acetylcholinesterase -> increases ACh at NMJ -> makes nondepolarizing muscular blockers less effective since they are competitive antagonists
potentiates depolarizing MRs: ie: succ
- Anticholinesterases partially inhibit pseudocholinesterases -> less breakdown of succinylcholine -> potentiates its effects
Phenytoin use affects muscle relaxants how?
Acute use: augments NMB
Chonic use: increases resistance to nondepolarizing blockade
Central anticholinergic syndrome aka atropine toxicity treatment
1-2mg of physostigmine (anticholinesterase w/ tertiary amine that passes into CNS)
How does trendelenburg affect aspiration intraoperatively?
Can increase risk for aspiration
If aspiration has already occurred, positioning them in T burg helps avoid worsening of aspiration
How do H2 blockers and PPIs affect gastric contents?
Increases gastric pH, but only newly secreted volume (not pH of gastric contents already in stomach)
Most likely source of ignition for airway fire
Laser
Neck (flexion/extension) can result in endobronchial intubation
flexion
- ETT tip follows the chin
- chin down pushes the ETT down
- chin up pulls the ETT up
(True/False) abdominal compartment syndrome is associated with increased ICP
True
__% of anesthesiology residents successfully re-enter anesthesiology training programs.
__% of anesthesiologists abuse drugs
34%
1%
_______ blocks carry the highest risk of nerve injury following peripheral nerve block
Interscalene blocks for shoulder sx
______ pressure monitoring is a method used to prevent peripheral nerve injury. What PSI is a sign of intrafascicular needle tip placement (bad)?
Injection pressure monitoring
Intrafascicular = > 20 PSI
- Extrafascicular has lower pressures < 20 PSI
Electrical stimulation with a motor response at ____ mA occurs with an intraneural needle tip (bad).
< 0.2 mA
Most likely initial symptom of malignant hyperthermia?
Respiratory acidosis
- Rising CO2
Aphonia after a thyroidectomy only occurs if _____ injury occurs.
b/l recurrent laryngeal n.
Which pts are at higher risk for cardiac perforation during lead extraction?
- Pts with lower BMI < 25
- thinner vessel walls - Females
- thinner vessel walls - Duration of oldest lead
- Removal of ICD leads > pacemaker leads
(Motor/Somatosensory) evoked potentials are extremely sensitive to volatile anesthetics
Motor
*Somatosensory can still be monitored as long as MAC < 0.5
Two tests for diagnosing MH
- Genetic testing
- Mutation in RYR1 gene - Caffeine/Halothane contracture test
- muscle biopsy
- GOld standard
You should avoid which type of solutions during repair of an AVM?
Hypotonic and glucose-containing solutions
- both can exacerbate cerebral edema
What is pneumoperitoneum?
Gas in the peritoneal cavity
- perforated ulcer
- subcutaneous emphysema
How does a pneumothorax affect the:
- pulse ox
- airway pressures
- ETCO2
Desaturation
- decrease blood to pulm capillaries
Increased airway pressures
ETCO2 decrease
Name that pulmonary change during laparoscopy!
- Desaturation
- Increased airway pressure
- Clinical exam: reduced air entry
Endobronchial intubation
Name that pulmonary change during laparoscopy!
- Desaturation
- Increased airway pressure
- Clinical exam: reduced air entry, hyperresonance, possible crepitus
Pneumothorax
- air leak in space btwn lung and chest wall (pleural space)
- Dont use PEEP, will make it worse
or
Capnothorax
- a pneumothorax via CO2
- Can use PEEP
Name that pulmonary change during laparoscopy!
- Desaturation
- No change in airway pressure
- Clinical exam: murmur, hypotension, ECG changes
Massive CO2 embolism
Name that pulmonary change during laparoscopy!
- No change in pulse ox
- No change in airway pressure
- Clinical exam: swelling or crepitus
- Sudden RIse in ETCO2 w/in 15 min of insufflation
Subcutaneous emphysema
Aspirin MOA
Irreversible COX inhibitor in platelets
- COX enzyme is required for production of prostaglandins (TXA2)
- New platelets are created every 2-5 days
ASA should be continued for most surgeries except:
- Intracranial neuro procedures
- Middle ear surgery
- Posterior eye surgery
- Spine surgery
- Prostate surgery
Stopping Dual antiplatelet therapy (ASA and ADP receptor antagonist) prior to scheduled surgery:
Bare metal stents
vs
Drug eluting stents
Bare metal stents
- continue for at least 1 month post op
- continue ASA perioperatively
vs
Drug eluting stents
- continue for at least 6 mo post op
- continue ASA perioperatively
Name that side effect!!
Echinacea
- Activation of cell-mediated immunity
2. Chronic immunosuppression
Name that side effect!!
Ephedra
- Ventricular arrythmias
2. Endogenous catecholamine depletion
Name that side effect!!
Garlic + Ginger + Ginko + Ginseng
(Four G’s)
- Inhibition of platelet aggregation
- Bleeding
*only gingseng can cause hypoglycemia
Name that side effect!!
Ginseng
- Inhibition of platelet aggregation
- Bleeding
- HYPOGLYCEMIA!
Name that side effect!!
Kava
Increased sedation
Name that side effect!!
Saw palmetto
- COX inhibition
2. Bleeding
Name that side effect!!
St. John’s wort
- CYP450 inducer
2. Delayed emergence
Name that side effect!!
Valerian root
- INcreased sedation
2. Increased MAC requirement
Benefits of using vasoconstrictor prior to nasotracheal intubation?
- Minimize mucosal bleeding
- Increases diameter of nasal passages by shrinking nasal mucosa
*does not decrease nasal trauma
Most commonly used agent to reduce aspiration
Metoclopramide
- central dopamine blocker
- stimulating upper GI function
- accelerate gastric emptying
*but mostly not necessary to give to all pts (except pregnant pts undergoing c/s)
Physiologic changes in elderly regarding neuraxial anesthesia
*all leads to faster onset and greater spread of LA in epidural space
- Increased dura permeability
- Decreased CSF volume
- Decreased fatty tissue in epidural space
- Increased compliance and decreased resistance
- leads to increased spread of LA
What is the sodium concentration in 5% albumin?
145 meq/L
Treatment for negative pressure pulmonary edema
- PEEP
- Diuretics
- Supportive
Dosing for dantrolene
2.5 mg/kg, up to 10 mg/kg
Older formulation of dantrolene is 20mg/vial
- may need 9-36 vials in a 70 kg pts
- Resonstitute in 60mL sterile water
Newer formulation Ryanodex contains 250mg
- reconstitute in 5mL sterile water
Do you continue MOAis perioperatively?
Yes
- if they are on it, they are probably refractory to other meds, and you can risk worsening depression/suicide
- but be careful of drug interactions (increased MAC, decrease cholinesterase activity)
What preop test does a pt taking apixaban need? What is its MOA?
None
NOAC
- direct factor Xa inhibitor ->
inhibit conversion of prothrombin to thrombin
What type of solutions are typically avoided for pts with an acute traumatic brain injury?
Colloids (4% albumin)
- SAFE trial: twofold risk of mortality
Why do pts with gastric banding procedures have lower risk of malabsorption compared to gastric bypass?
Stomach and small intestines remain intact
Peak plasma levels of lidocaine occur after ____ hours following injection
12 hours
- LAST manifests
Why is neuraxial anesthesia contraindicated in liposuction using tumescent anesthesia?
Risk for vasodilation
Hypotension
Volume overload
How does hepatorenal syndrome develop?
It’s a prerenal response to late stage cirrhosis
End stage cirrhotic pts develop portal HTN d/t liver fibrosis and splanchnic arterial vessels dilate to promote more blood flow in portal vasculature ->
Kidneys become hypoperfused -> renal arterial vasoconstriction -> retention of sodium and water.
25% albumin is ___x more [ ] than std human serum albimin, and can restore intravascular oncotic pressure
5x
- give 25% albumin at 1g/kg
Why do you have to consider cyanide toxicity in pts with recent burns or smoke exposure?
Release of cyanide from burning plastics
Classic finding of cyanide toxicity
elevated mixed venous oxygen saturation despite progressively worsening metabolic acidosis
- oxygen effectively bypasses tissues and returns to venous circulation without being utilized
Classic finding of methemoglobinemia
fixed oxygen sat on pulse ox of 85%
- d/t how methemoglobin absorbs the wavelengths of light
Abdominal compartment syndrome is an increase in intraabdominal pressures _______ mmHg that results in organ damage. It is measured via ______
greater than 20 mmHg
bladder pressure
The most common organ affected by Abdominal compartment syndrome is the _____
kidney
- most susceptible to hypoperfusion
_____ is the preferred imaging modality used for radiation planning
CT scan
- provides 3D electron density values to calculate radiation doses
Implants contraindicated in MRI suite
- ICDs (some)
- Cochlear implants
- Pain pumps
- Peripheral n. stimulators
- Aneurysm clips
Most significant risk factors for perioperative VTE (5)
- Major lower extremity arthroplasty
- Recent stroke w/in 1 mo
- Spinal cord injury
- Multiple trauma
- Fx of hip, pelvis or LE
Normal shunt fraction during a case where one lung ventilation is required is around ____% in an otherwise healthy pt
20-30%
Pulmonary vascular resistance is lowest when the lung is at its _____
Functional residual capacity
The physiologic response to endobronchial intubation and one lung ventilation is to increase PVR in the (ventilated/nonventilated) lung through _______, in an effort to decrease the shunt fraction
non-ventilated
Hypoxic pulmonary vasoconstriction
Most significant risk factor for emergence delirium?
Age - children (2-6 y.o)
*h.o emergence delirium is NOT a risk factor
Which volatile anesthetics are more likely to cause emergency dilirium?
Sevo/Des/Iso»_space; TIVA > Halothane
Methohexital is commonly used for LA of the vocal cords prior to medialization procedures, retrobulbar or peribulbar block.
What is its MOA?
Ultra short acting barbiturate
Pts with an Aldrete score of ___ can be discharged from phase I.
9 or higher
5 Parameters of the Aldrete score
- Respirations
- Color
- Consciousness
- Circulation
- Activity
Why does GFR decrease as pts age, but not Creatinine?
GFR decreases by 30-40%,
but Lean body mass also decreases
- Overall, no net change in plasma creatinine
Explain what happens physiologically when a pts undergoes electroconvulsive therapy (inducing a tonic clonic sz w/ large increase in cerebral blood flow and metabolism)
Initial parasympathetic response
- bradycardia
- asystole
Followed by sympathetic outflow
- HTN
- Tachycardia
Gold standard induction agent for electroconvulsive therapy
Methohexital 1 mg/kg
- does not change sz duration
- can blunt the hemodynamic response to sz
Factors ____ and ____ are produced in endothelial cells and are thought to be increased in liver disease
Factor VIII and vWF
Liver disease reduces factors ______.
II, V, VII, IX, X, XI
Liver disease affects (procoagulants / anticoagulants)
both
In liver disease pts, when is it necessary to give FFP for elevated INR levels?
almost never
- do not chase INR levels
- Does not reflect risk of bleeding
