Module 1 Flashcards
What causes Myasthenia Gravis?
Autoimmune B cell activation d/t infectious agent attacks acetylcholine receptors
What is Myasthenic Syndrome?
What causes it?
Decreased release of acetylcholine.
Usually paraneoplastic
Strength actually increases with exercise.
What is Neostigmine?
Acetylcholinesterase Inhibitor.
Increases amount of circulating acetylcholine.
What is HyperPP?
What channel does it effect?
Hyperkalemic Periodic Paralysis.
Na channel defect.
Basically can’t regulate changes in K level greater than 5.
What is HypoPP?
What channel is effected?
Hypokalemic Periodic Paralysis
Can’t tolerate K less than 3.0
CALCIUM or SODIUM CHANNEL DEFECT
What should be considered when administering anesthesia to a patient with any skeletal muscle channelopathy?
No succ. Susceptible to MH.
Optimize electrolytes
What is Anderson - Tawil Syndrome?
K channel defect with LOTS of cardiac conduction issues.
Develop periodic paralysis with that may or may not be associated with K level (hypo/hyper/normo).
Ten percent suffer a cardiac arrest!
What is Myotonic Dystrophy?
What considerations should be made for their anesthesia? (3)
Skeletal muscles are unable to repolarize after contraction.
- Extreme reaction to succ.
- PNS unreliable.
- Can get resp depression from narcs
What is Congenital Myopathy?
What anesthesia considerations should be made? (2)
Hypotonia and weakness at birth.
- Lots of respiratory mm dysfunction.
- SUSCEPTIBLE TO MH.
What is Duchenne Muscular Dystrophy?
How does it manifest?
What anesthesia considerations should be made? (3)
X linked recessive.
absence of Dystrophan.
Progressive paralysis, starts around age 12.
- Need cardiac eval every 2 years.
- No succ (rhabdo and hyperkalemia). Avoid halogenated inhalants
- Dysfunctional GI tract means increased risk of aspiration.
What is Becker Muscular Dystrophy?
Less severe than DMD. Later onset. Reduced cardiac risk, eval every 5 years.
What causes Guillain - Barre?
What are the manifestations?
Anesthesia considerations?
Autoimmune response to an infection causes the body to attack your nerves, moving from distal to proximal.
Resp dysfunction. Autonomic dysfunction can cause hypotension/tachycardia.
Noxious stimuli like intubation can cause large autonomic response.
Malignant Hyperthermia Common Triggers (4)
Succinylcholine
Halogenated Inhalants
Extreme physiologic stress
Heat exhaustion
MH Cause
Mutation of the ryanodine recepter
permits uncontrolled releast of Ca from sarcoplasmic reticulum
First Sign of MH
Increased ETCO2 that does not respond to increased ventilation
Acute Malignant Hyperthermia S/S
Muscle rigidity
Masseter Spasm
Respiratory AND metabolic acidosis
Hyperthermia may develop early or late
Dantrolene
Inhibits pathologic release of Ca
Initial dose 2.5mg/kg
May require up to 10-20 mg/kg
Which drugs are safe for MH susceptible patients?
What precautions should be taken in MH susceptibility?
OK: prop, benzos, opioids, NDMA, Nitrous
Remove or close all vaporizers
Flush machine with 100% O2
Charcoal filters
Have dantrolene readily available
What is Porphyria?
Manifestations?
Enzyme deficiencies in the Heme synthesis pathway cause a buildup of heme precursors that are toxic to the nervous system
Acute: Fever, tachycardia, N/V, ab pain, weakness, seizures, confusion, hallucinations
SEVERE Muscle weakness with resp failure
Hyponatremia (2/2 SIADH)
What drugs should be avoided with Porphyria?
When should porphyria be suspected?
barbituates and etomidate.
Delayed emergence or prolonged mm weakness after anesthesia
How is Acute Porphyria detected?
Urinary porphobilinogen detected within 5 minutes
What is Plasma Cholinesterase?
Enzyme synthesized in the liver to break down acetylcholine
ALSO Breaks down succinylcholine, mivacurium, procaine, chloroprocaine, tetracaine and cocaine.
What usually causes Cholinesterase Disorders?
What are some anesthetic concerns?
Usually caused by hepatic disease (cholinesterase is synthesized in the liver)
It hydrolyzes certain drugs, making them much more potent and long lasting
Since cholinesterase disorders are often undiagnosed until surgery, what is a prudent practice to prevent prolonged apnea?
Be certain that recovery from the initial dose of succ has occured before administering more muscle relaxant (succ or nondepolarizing)
What are Glycogen Storage Diseases?
Inherited
Caused by abnormal enzymes regulating glycogen synthesis and breakdown
LOTS OF DIFFERENT TYPES
What are the critical components of all Glycogen Storage Disease?
Acidosis (from fat and protein metabolism)
Hypoglycemia
Cardiac and hepatic dysfunction (2/2 destruction and replacement of normal tissue with accumulated glycogen)
What is Mucopolysaccharidosis?
autosomal recessive deficiency of lysosomal enzyme that cleaves mucopolysaccharides
MPSs accumulate in the brain, heart, bone, liver, cornea, and tracheobronchial tree
Progressive craniofacial deformities, joint and skeletal anomalies, cardiac involvemtn, early death
Tough to intubate d/t lots of facial abnormalities
What are some anesthetic considerations for patients with muchopolysacharidoses?
- Upper airway deformities make intubation difficult
- Cardiorespiratory Dysfunction d/t fat deposits in the heart
- Best to do a slow induction with sevo
- May want preop echo
What are the hallmarks of Osteogensis Imperfecta?
Brittle bones
lax joints
tendon weakness
cardiac problems
blue sclera
platelet dysfunction, abnormal airway anatomy, pectus deformities
CAREFUL POSITIONING DURING ANESTHESIA
What are the four Nutritional Anemias?
Iron
Vit B12
Folate
Anemia of Chronic Illness
What is Hereditary Spherocytosis?
What are some manifestations?
HEMOLYTIC ANEMIA caused by misshapen and fragile RBCs
cholelithiasis, splenomegaly, jaundice
What is G6PD?
What does it cause?
most common human enzymopathy
HEMOLYTIC ANEMIA caused by deficient NADPH in RBCs
Oxidative stress d/t inability to buffer FRs leads to hemolysis of RBCs
What is Pyruvate Kinase?
What does a deficiency cause
enzyme responsible for half of the ATP production in RBCs
HEMOLYTIC ANEMIA
Sickle Cell Disease is a _________.
HEMOGLOBINOPATHY
Reduces life cycle of RBCs from 12o days to 12 days
What is Thalassemia?
What causes it?
HEMOGLOBINOPATHY
Either a or b globin production is inhibited, and the other is over produced
Excess unpaired globins cause cellular and tissue damage
Causes iron overload
Bone marrow deposits in spinal cord. Difficult airway.
What are some anesthetic considerations for patients with SLE?
- CXR, PFT, Echo
- Renal function tests
- Increased risk of infection
- Will most likely need steroids continued intraop
What is Scleroderma?
Systemic sclerosis
swelling and thickening of skin and organs, which eventually become fibrotic
What is Dermatomyositis?
What are the s/s?
What organ is heavily effected?
INFLAMMATORY MYOPATHY
Autoimmune muscle necrosis
Proximal mm weakness and heliotrope rash, periorbital edema, lesions on knuckles
50% have pulmonary disease
Aspiration pneumonia common
Avoid succ. May need postop mech vent
What are some anesthetic considerations for patients with Epidermolysis Bullosa?
May have undiagnosed cardiomyopathy
Minimize trauma to skin and mucous membranes
AVOID LATERAL SHEARING
Pad BP cuff
What is Pemphigus?
Autoimmune blistering disease
Oral lesions in most
larynx, esophagus, urethra, conjunctiva, cervix and anal lesions too
Corticosteroid therapy helps
Causes of decreased WBC (4)
SLE
Overhwelming Sepsis
Autoimmune disease
Decreased Bone marrow
Causes of Increased WBC (5)
Steroids
Inflammation
Infection
Leukemia
Severe Stress
Causes of Hyperkalemia (5)
Dietary
Renal Failure
ACE inhibitors, aldactone, bactrim
Reduced aldosterone
Rhabdo
Causes of Hypokalemia (4)
Excess Aldosterone
Excess Sweat
Diuretics
Dietary, GI Loss
What are the three Primary Mechanisms of Nerve Injury?
Transection
Stretch
Compression
What are Fascicles?
Bundles of Nerve Fibers
Building blocks of peripheral nerves
What are Schwann Cells?
What are the two types?
Cells that form a nerve sheath (or neurolemma) over axons in nerve fibers.
Myelinated or non-myelinated
What is Ischemic Optic Neuropathy?
What causes it?
Optic n is in a watershed area, particularly vulnerable to ischemia during hypoperfusion
Not caused by pressure directly on the globe, but by decreased oxygen delivery
What is Central Retinal Artery Occlusion?
What causes it?
CRAO
The entire retina’s blood flow is completely cut off
Causes: Emboli, External pressure on the globe,
What are the components of the BURP manuever?
B: Larynx displaced Backward
U: Upward
R: to the Right, using
P: Pressure over the thyroid cartilage
What is Mendelson Syndrome?
What are the s/s?
Another name for Aspiration Pneumonitis
SOB
Wheezing/Coughing
hypoxemia
cyanosis
pulmonary edema
hypotension
What is the treatment for an upper Airway Obstruction?
decadron 0.1-0.5 mg/kg
humidified O2
Epi
When RLN is unilaterally damaged, the vocal cords adjust by shifting their midline to the _______ side
uninjured
The larynx begins with the _____ and extends to the ______
Epiglottis, Cricord Cartilage
The nasopharynx lies anterior to ___ and is bound superiorly by _______ and inferiorly by the ______.
C1
Base of the skull
Soft Palate
The oropharynx lies at the ____ level and is bound superiorly by ______ and inferiorly by the ____.
C2-C3
Soft Palate
Epiglottis
The hypopharynx lies posterior to the ___ and is bound by the superior border of the ____ and the inferior border of the ______ at the ____ level.
larynx
epiglottis
cricoid cartilate
C5-C6
Extrinsic Muscles that elevate the larynx
• Stylohyoid • Digastric • Mylohyoid • Geniohyoid • Stylopharyngeus • Thyrohyoid
External Muscles that lower the larynx
Omohyoid • Sternohyoid • Sternothyroid
What does ADVISE stand for?
Anticipate
Differential Diagnosis
Vigilance
Internal Sense of Suspicion
Safety Routine
Evidence Based
What is the IV Flow Rate 16#?
18#?
20#?
180 ml/min
90 ml/min
60 ml/min
What does MSMAIDS stand for?
Machine
Suction
Monitors
Airway, Alarms, Ambu
IV Lines
Drugs
Special Considerations
What does PRIDE stand for?
Personal
Responsibility
In
Developing Excellence
ASA 1
Normal Health Patient
ASA 2
Mild Systemic Disease
No Functional Limitations
ASA 3
Severe systemic disease with functional limitations
Angina, Severe COPD, uncontrolled HTN
ASA 4
Severe systemic disease that is a constant threat to life
ASA 5
Moribund, not expected to survive without operation (ruptured AAA, PE, Head Injury with increased ICP)
ASA 6
Organ Donor
Sensitivity
e.g. recall rate, true positive
How capable a test is of telling whether or not someone HAS the disease
Percentage of sick people who are correctly identified as having the condition
Specificity
Probability of a negative test result if the patient DOESN’T have the disease
How many not pregnant women does it determine are not pregnant?
Who should always get a preop CBC?
Neonates
Malignancy
Age > 75
Renal/Liver Dz
Tobacco Use
Anticoag use
Who should always get a coag panel?
Anticoag Use
Chemo
Liver/Renal Dz
Bleeding Disorder
Who should get a preop chem panel
CNS disease
Diuretics, dig, steroids
Elderly
Malnutrition
Diabetes
Renal/Liver Dz
Who should get a pre-op BUN/Cr
Elderly (>75)
Renal Dz
Diabetes
Diuretics, Dig Use
CV disease
Who should always get a preop BG?
Diabetic
Steroid Use
CNS disease
> 75yo
Who should get a preop CXR?
CV disease
>75
Pulm Disease
Malignancy
Radiation Therapy
Tobacco > 20 py history
Who should get a preop ECG
CNS disease
Cardiac disease
Pulmonary Disease
Radiation
DM
Digoxin Use
High Risk Procedure
What is the calculation for Male IBW?
105 + 6 for each inch over 5 ft
What is the calculation for Female IBW?
100 + 5 per inch over 5 feet
What is the 3-3-2 Rule?
3 mouth opening
3 HyoMental
2 Thyromental Distance
Malampati 1
Soft Pallate, Uvula, Tonsilar Pillars
Malampati 2
Soft palate, upper portion of uvula
Malampati 3
Soft Palate
Malampati 4
Hard Palate
List 9 Nonreassuring Airway Exam Findings
Long upper incisors (front teeth)
Prominent overbite
Unable to move mandibular incisors anterior to maxillary incisors
Uvula not visible when tongue out sitting up
Highly arched or narrow palate
Noncompliant Mandibular Space
Thyromental > 3 fingerbreadths
Short or thick neck
Limited ROM
Why should you get an ECG on a diabetic patient?
High risk for silent ischemia, especially with autonomic dysfunction
Check ECG for Q waves (signs of old infarct)
Metabolic Syndrome
Combo of HTN, HLD, hyperglycemia, obesity
higher rates of cardiac/pulm/renal events
1 MET
Poor functional Capacity
Can walk 1-2 blocks and perform self care
4 METS
Good functional capacity
run short distance, light to heavy housework, throwing a ball, dancing
10 METS
high functional capacity
strenuous sports
A patient who is scheduled for a knee replacement just had balloon angioplasty. How long should they wait?
Elective procedure –> 14 days
What is the optimal waiting period for noncardiac elective surgery after DES placement?
6-12 months
What are risk factors for requiring postop reintubation?
ASA > 3
Emergency Procedure
High Risk Sx
Hx of CHF
Chronic Pulm Disease
Should nicotine patches be used perioperatively?
No! Associated with increased mortality
What do statins do?
- Lower lipids
- Enhance nitric oxide mediated pathways
- Reduce expression of cytokines and adhesion molecules
- Lower CRP
Anti-inflammatory, vasodilatory, antithrombotic
Top ten risk factors for aspiration
Emergency
Inadequate Anesthesia
Obesity
Opiods
Lithotomy
Neuro deficit
Reflux
Hiatal Hernia
Abdominal Pathology
Difficult intubation/airway
What’s the fasting time for breastmilk vs formula?
BM 4 hrs
formula 6 hours
Ranitidine
Classification
Dose
Onset
Duration
H2 receptor antagonist
150 PO, 50 IV
Effective in an hour
lasts 9 hours
Omeprazole
Classification
Dose
Onset
Duration
PPI
40mg IV 30 min preop
Lasts up to 24 hours
Reglan
Classification
Dose
Onset
Duration
Dopamine Antagonist, increases motility
Handy in pregnant ladies and other suspected to have large gastric volume (slowed emptying)
Midazolam
Onset 1-2 min
Peak 0.5-1 hour
Duration: 1-4 hours
Anxiolysis, sedation, amnesia
Why does Lorazepam have such a long duration?
5-10x more potent than diazepam
LONG duration d/t increased affinity for GABA receptor
Well suited for chronic anxiety or long case
What are indications for anticholinergics?
Antisialagogue (glycopyrrolate)
Sedation and Amnesia (scopolamine)
Vagolytic Effect (atropine)
Side effects of anti-cholinergics
Anticholinergic Syndrome (delirium, hallucinations)
Intraocular Pressure (mostly scop)
Hyperthermia (interferes with sweating)
When should preop Vanc be given?
2 hours preop
If a tourniquet is used, when should preop ABX be given?
BEFORE inflation
ABX with broadest skin coverage
cephalosporins
Vertical Location of the Larynx in an infant
C3-C5
Why is limited jaw protrusion concerning?
Difficult tongue displacement
Why are large central incisors concerning?
Obstructed view
Retrognathia
Overbite
Makes tongue displacement difficult
What does the thryomental distance tell you?
Neck mobility
degree of retrognathia
Prognath
Bring lower incisors anterior to upper incisors
Are the components of an airway exam more sensitive or specific?
More specific! If a patient has an indicator of a difficult airway, they may or may not end up being difficult. But if they DON’T have that component, it’s very reassuring
What neck positioning should be used for VIDEO laryngoscopy?
Supine neutral rather than sniffing
What is Dystrophan?
Large protein
Stabilizes the muscle membrane
Enable signaling between cytoskeleton and and ECM
What drug should be given to Parkinson’s patients if they can’t take oral levadopa?
Apomorphine
What drugs should be avoided in Parkinson’s?
Dopamine antagonists: reglan, droperidol, phenothiazines (compazine)
Which anticholinergic does not cross the blood brain barrier?
Glycopyrrolate (Ideal for alzheimer’s patients)
HypoPP Precipitating Factors
High Glucose Meals
Strenuous Exercise
Glucose-Insulin infusions
Stress
Hypothermia
Huntington Disease
Cause
Onset
Symptoms
Inheritance
Autosomal Dominant
Mutant huntingtin protein
Onset at 35-40
Choreifrom movements, depression, dementia
What is Amyotrophic Lateral Sclerosis?
Which drugs should be avoided?
UMN and LMN dysfunction
Autonomic Dysfunction
Only use short acting drugs. No succ.
Creutzfelt Jacob Disease
Prion Infection
Vacuolization of brain
Dementria, myoclonus, EEG changes
HIGHLY INFECTIOUS
When should porphyria be suspected?
Patients with unexplained elayed emergence from anesthesia or postop muscular weakness
Susceptible patients are rarely identified pre-op
Why aren’t infants able to modulate their CO?
No ability to change their stroke volume. Can only change their heart rate. That’s why bradycardia is so scary and dangerous in babies
What factors increase CO2 production?
Anything that increased metabolic rate:
Hyperthermia
Sepsis
Hyperthyroidism
MH
Shivering
What factors decrease CO2 production?
Anything that decreases metabolic rate:
Hypothermia
Hypothyroidism
Do you see elevated or decreased ETCO2 during Pulmonary Embolism?
Hypoventilation?
Hypoperfusion?
Decreased
Increased
Decreased
What does the MAC value demonstrate?
the MINIMUM ALVEOLAR CONCENTRATION
the end-tidal gas concentration that when maintained constant for 15 minutes at a pressure of one atmosphere, inhibits movement in response to a midline laparotomy incision in 50% of patients
What do cardiac oscillations on ETCO2 indicate?
That CO2 flow is low enough that the movement of the heart is detected. Generally represents a need for mechanical ventilation
When is the relationship between ETCO2 and PaCO2 not reliable?
When there is an increase in dead space ventilation or V/Q mismatch
Emphysema, Very low CO states,
iatrogenic single lung ventilation
pulmonary embolism
Capnography will UNDERESTIMATE ETCO2 levels
Why does ETCO2 monitoring on neonates become problematic
The side-flow monitor sucks up 200ml/min to assess ETCO2, but a neonate MV may only be 300. The machine may not be getting a good sample.
Where is the art line transducer zeroed during neurosurgical sitting cases?
Circle of Willis
What Art Line practices should be avoided in peds?
Minimize flushing
No power flushing (may cause retrograde flow in cerebral arteries)
Blood wasted should be returned through the vascular system, not the arterial system
NIBP MAP Calculation
MAP = DP + (SP − DP)/3
As the site of NIBP is moved peripherally, what happens to the SBP and DBP?
SBP increases, DBP decreases
Increased pulse pressure
In what population is NIBP arm pressure not reliably similar to ankle pressure?
pregnant women
Where should a BP cuff be placed on a preemie?
R upper arm (preductal)
What does pulmonary wedge pressure estimate?
LV EDP
Left Ventricular End Diastolic Pressure
CVP waveform: Changes with A Fib
No A waves
CVP waveform: Large A waves
increased RA pressure (tricuspid stenosis, RV hypertrophy, lung disease, PHTN)
What do CVP a, c and v waves represent?
Atrial contraction
Tricuspid closure/RV contraction
RA filling
What are the pros of a subclavian CVC?
Lower rates of infection
When should a Subclavian CVC be used with caution?
Coagulopathic patients. Can’t be effectively compressed if the vessel is ruptured.
In what population are femoral CVCs NOT associated with increased infection?
Pediatrics
What are s/s of PA rupture?
Sudden cough
hemoptysis
hypotension
Who is most at risk for PA catheter rupture?
Elderly
pHTN
Anticoagulants
What abnormalities make CO monitoring via PA unreliable?
Anything that changes flow such that retrograde flow along the catheter can occur:
Intracardiac shunts
Tricuspid Regurg
What is FATD?
femoral artery Thermodilution
Used in pediatrics
Pretty accurate, way less risky
During PPV, what will happen to your SBP?
SBP will decrease during inspiration because intrathoracic pressure is higher
If the difference is dramatic, may indicate hypovolemia
Four modes of heat loss
radiation (like the sun radiates heat)
evaporation (0.58 kcal lost per gram H2o evap)
convection (breeze blowing)
conduction (cold OR table)
What effect does ketamine have on processed EEG
Causes fluctuations in the oscillations that don’t correlate with depth of anesthesia
Processed EEG monitoring is unreliable when using what drugs?
Ketamine and Nitrous Oxide
What is the role of processed EEG in assessing for cerebral ischemia
Not helpful
Only analyzes the frontal lobes
at best serves as regional perfusion monitor
What range of BIS monitor readings represent general anesthesia?
40-60
What range of SedLine EEG readings correlate with general anesthesia?
25-50
If given together, will an EEG reading change in response to opiods or propofol?
Propofol only. Opiods usually don’t effect EEG
What surgeries represent a higher risk of awakeness?
Any surgery where you can’t administer a lot of anesthetics safely:
C-Sections
Hemodynamic Instability
Trauma Laparotomies
What patient position presents dangerous use of EEG monitoring?
Prone. May damage skin. Use carefully.
What is the incidence of intraop awakeness in pediatrics?
three times higher than adults!
What effect may anesthetic gases have on children?
decline in IQ and listening comprehension
What happens when nerves are stretched beyond their resting length?
Even 5% stretch can cause kinking of arterioles and cause ischemia
If shoulder braces are needed, where should they be placed?
Over the acromioclavicular joint
Brachial plexus injury less likely there than over the traps
What factor is responsible for brachial plexus injuries in median sternotomies?
The degree of rib displacement by retractors
Not reliably related to patient positioning
What is the etiology of long thoracic nerve dysfunction after surgery?
Likely due to viral/inflammatory origins
Not related to positioning
Why is abducting the arm >90 degrees dangerous?
Both compresses and stretches the axillary a/v/n bundle
Thrusts the head of the humerus into the axillary a/v/n bundle
What are common causes of post op radial nn damage?
Pressure from vertical bar of anesthesia screen
excessive NIBP cycling
Compression at midhumerus from sheets/towels
What is the likely cause of median nerve damage?
Forcible extension of the elbow
What is the most common post op neuropathy
Ulnar nn damage
Causes of ulnar nn damage
Prolonged Elbow Flexion
Inflammation
Why is ulnar n damage more common in men?
Larger tubercle of coronoid process
Less adipose tissue over medial elbow
What is hyperlordosis
Hyperextension of the lumbar spine
If greater than 10 degress may cause spinal nn ischemia
What are some positioning related causes of compartment syndrome
- Systemic hypotension and loss of driving pressure to extremity (i.e. elevation)
- Vascular obstruction of major leg vessels
- External compression of the elevated extremity
Why is the lateral jacknife position used?
Widen intracostal space
Should take patient out of this position once the rib spreader is placed
V/Q in AWAKE Lateral Decubitus Positioning
In an awake patient, when they are placed in LD both perfusion (which is gravity dependent) and ventilation (which is increased by diaphragm displacement) increase in the DEPENDENT lung, and a V/Q mismatch is avoided
V/Q in ANESTHETIZED Lateral Decubitus Positioning
Perfusion in dependent lung is increased by gravity,
BUT
when anesthesia is given, there is a reduction in lung volume in BOTH lungs. This causes the UPPER lung to be compliant but underperfused, and the LOWER lung to have decreased compliance but increased perfusion
V/Q Mismatch
Why do long spinal cases have increased incidence of ischemic optic neuropathy?
Prone positioning
If head is lower than heart, leads to venous and lymphatic congestion in optic nn
How long should a lateral head displacement while prone be continued?
Should be less than three hours. If procedure is longer, consider keeping the head in the sagittal plane
What are some methods to reduce the likelihood of post op blindness in prone cases?
- Allow patients’ head to be above the heart
- Use colloids AND crystalloid for volume management
- Position to reduce intra-abdominal pressure
- Be cautious with wilson frame
- Consider staging procedures longer than 5 hours to reduce risk
Thoracic Outlet Syndrome
Patients will have pain when lifting arms above head
Before pronating patients, make sure they can clasp their hands behind their neck to rule this out
Why can prone positioning cause increased spinal bleeding?
If abdominal pressure approaches or exceeds venous pressure, vertebral venous plexuses that empty directly into the IVC back up into the perivertebral and intraspinal circulation, causing venous congestion and increased bleeding
What are the most common risk factors of venous air embolism?
- Neuro and ENT surgeries (especially if surgical incision is located 2 in or more above the level of the RA)
- Surgeries on noncollapsed veins or sinuses
- Procedures causing a pressure gradient (CVC placement)
How is a diagnosis of venous air embolism obtained?
- Most sensitive: Echo
- Highly sensitive: Transthoracic Doppler
- low sensitivity: Esophageal stethoscope, PA, ECG
Why are patients with venous air emboli placed in L Lateral Decubitis or Trendelenburg position?
Moves air embolus from the RVOT into the RV, decreasing risk of cardiovascular collapse
What should be done if a venous air embolism is suspected?
Cover surgical field with soaked dressing and flush with saline
100% O2
D/C Inhalants
Vasopressors for hypotension
Attempt manual removal of air (not normally effective)
What should be done to prevent venous air embolism in cases where the risk is known?
CVC and transthoracic doppler placement
Avoid nitrous oxide
Consider alternative patient positioning
Why is face/neck/tongue edema a complication of a head-elevated position?
Prolonged, marked neck flexion can cause venous and lymphatic obstruction resulting in macroglossia
What is midcervical tetraplegia?
Hyperflexion of the neck stretches the spinal cord resulting in ischemia to the midcervical region. Causes paralysis below C5.
Associated with any prolonged flexion of the head (sitting or supine, forced or nonforced)
Which structure is most frequently injured during a nasal intubation?
inferior nasal concha
What is the role of the Genioglossus?
Attaches the tongue to the mandible, prevents it from falling back during jaw-thrust
What is the role of the Internal branch of SLN?
provides sensory innervation to the posterior epiglottis, arytenoids, and vocal cords
Croup involves edema of the
airway below the vocal cords
You are applying local anesthetic soaked pledgets to the middle turbinates of a patient’s nasal cavity prior to a nasal intubation. What nerves are you anesthetizing?
Trigeminal Nerve
what is the vertical location of the adult larynx?
The pediatric larynx?
C3-C6
C2-C4
What are the objective criteria for routine extubation? (5)
vital capacity of at least 10 mL/kg, a
peak NIP of at least -20 cm H2O
sustained tetanic contraction
tidal volume of at least 6 mL/kg
TOF ratio of at least 0.7.
When is retrograde intubation useful?
situations where traditional intubation is not possible, but ventilation is possible.
How is a cricothyrotomy performed?
inserting a large-bore intravenous catheter or cannula into the cricothyroid membrane which lies between the inferior border of the thyroid cartilage and the superior border of the cricoid cartilage.
What is the invasive airway technique of choice in emergency airway situations?
surgical cric
Following a difficult intubation, you suspect that a patient may have obstruction of the submandibular duct due to trauma establishing the airway. This condition would present as
swelling of the tongue
Laryngotracheobronchitis (croup) most commonly appears _____ after extubation.
3 hours
Which nerves should be assessed for onset of NMBA and why?
Blood, thus drug, distribution to the facial muscles mirrors distribution in the larynx and diaphragm where relaxation is required for intubation and airway manipulation.
Which nerves should be assessed to discern recovery from NMBA
Recovery is best measured in the hand. The hand muscles are more sensitive to relaxant than the diaphragm, so if recovery is evident in the hand, the larynx, and the diaphragm, the upper airway muscles will be recovered as well.
What is Fade?
Inability to sustain a muscular response to repetitive nerve stimulation
Why is fade an assessment of NMBA activity?
NMBAs block the presynaptic Ach receptors as well as postsynaptic
When the nerve can’t continue producing Ach to stimulate contraction, that’s the effect of the NMDA and its called fade
When the fourth twitch disappears in ToF, what is the percentage of block?
75-80%
If T3 and T4 are absent in ToF, what is the percentage of block?
T2?
0 Twitches?
80-85%
90-95%
100%
What is Tetanus Testing?
Allows assessment of NM blockade when there is a deep block needed
continuous electrical stimulation for 5 seconds at 50 or 100 Hz. If the muscle contraction produced is sustained for the entire 5 seconds of stimulation without fade, significant paralysis is unlikely. If fade is present, clinically significant block remains.
Which drugs are helpful in slowing Alzheimer’s?
Cholinesterase Inhibitors
Which form of hemoglobin is most commonly seen in the bloodstream
Hgb A is 97% of RBCs
Hemoglobin C is implicated in a type of hemolytic anemia, hemoglobin F is found in fetuses, and hemoglobin S is found in patients with sickle cell anemia
What pulmonary complications would you most likely see in a patient with systemic lupus erythematosus?
Restrictive defects such as:
Pleural Effusion
pHTN
What is the most common cause of death in lupus?
Renal Disease
The most common presenting symptoms of SLE are polyarthritis and dermatitis. A malar rash occurs in about 1/3 of SLE patients. Renal disease occurs in over half of the patients with SLE and is the most common cause of death. About 10-20% of patients with lupus erythematosus require dialysis. Because of the increased risk of vasculitis, these patients have a higher risk of CNS disorders such as seizures, stroke, dementia, peripheral neuropathy, and psychosis. A diffuse serositis results in pericardial effusion in over half of these patients, but pericardial tamponade is rare.
With its decline in age, which neurotransmitter is noted for its connection to Alzheimer’s disease?
Acetylcholine
What are two non-depolarizing muscle relaxants useful for patients with Guillain-Barre syndrome?
Cis and Roc
What is the preferred treatment for hereditary Spherocytosis?
Splenectomy
Considering the elimination half life of carbon monoxide, what is the minimal time of smoking cessation to substantially decrease carboxyhemoglobin levels?
18 hours
How long should a patient refrain from smoking before the ability of the lungs to respond to pulmonary infection returns to normal?
8 weeks
How long prior to surgery should aspirin be discontinued?
7-10 days
What food allergies are associated with an increased risk for latex allergy?
Papaya
Kiwi
Chestnuts
Avocado
What is the overall risk for a perioperative MI in the general population undergoing general anesthesia?
0.3%
characteristics of unstable angina
substernal chest pain that began less than 2 months ago,
has progressively increased in severity, duration, or frequency,
is less responsive to pharmacologic therapy,
occurs at rest,
lasts longer than half an hour, or
exhibits transient T-wave or ST segment changes.
Ideally, a pulmonary artery catheter should be positioned in
West Lung Zone III
Which disease are associated with cannon ‘a’ waves on the central venous pressure waveform
junctional rhythms, complete AV block, or PVCs,
triscupid stenosis, mitral stenosis,
myocardial ischemia, diastolic dysfunction, and ventricular hypertrophy
How is the post-tetanic count used?
Used in deep anesthesia to determine how long it will be until a response to stimulation will occur
The number of visible twitches correlates inversely with the amount of time required for return of the first twitch of a TOF stimulation.
how do you elicit a post-tetanic count?
5 second 50 Hz tetanic stimulation followed by a 3-second pause, then 1 Hz twitch stimulations
Which clotting factors are not synthesized by the liver?
factors III (tissue thromboplastin), IV (calcium), and von Willebrand factor
Sugammedex has the highest affinity for what paralytic?
Rocuronium
To what degree can succ increase intraocular pressure?
as much as 15mmHg for 5 minutes
Which two laboratory studies appear to be associated with increased risk of perioperative pulmonary morbidity?
High BUN and low Albumin
What is the appropriate intravenous dose for succinylcholine in a 3 month-old patient?
2-3 mg/kg
Require a higher dose than adults
Defasciculating doses of nondepolarizing neuromuscular blockers are rarely given because fasciculations are uncommon in children.
Which agents have been noted to delay the onset of rocuronium?
Beta Blockers
Methemoglobinemia tends to drive the pulse oximetry measurement towards _____ regardless of the actual oxygen saturation
85%
can occur due to large doses of benzocaine, prilocaine, or EMLA cream
absorbs the two frequencies of light used in pulse oximetry in a 1:1 ratio, which corresponds to an oxygen saturation of 85%
The prothrombin time and INR are good indicators of hepatic dysfunction due to the short half-life of clotting factor:
7
What is the most serious side effect of sugammedex?
Hypersensitivity
Why is edrophonium a weaker reversal agent than neostigmine?
Binds with ionic bonds
How does severe anemia affect SpO2 readings?
Overestimates
What causes underestimation of SpO2?
Prominent venous pulsations and injection of certain dyes such as indigo carmine, lymphazurin, nitrobenzene, indocyamine green, methylene blue, and patent blue can result in underestimation
What is the half life of ancef?
2 hours
What nerve passes between the medial epicondyle of the humerus and the olecranon?
Ulnar
What percentage of MIs occur without symptoms?
30%
Which muscle relaxant would be LEAST appropriate for a patient with a history of severe asthma?
Atracurium
What inhaled anesthetic potentiates the effects of neuromuscular relaxants the most?
Desflurane
Why is pancuronium popular in cardiac surgery?
has direct sympathomimetic and vagolytic effects
capable of counteracting bradycardia that is induced by a high dose narcotic technique.
How is potency of NMBA agents expressed?
By ED95: the dose required for supression of 95% of baseline twitch height
What is a Phase II Block of Succ?
Pardoxic Non-paralysis
What causes phase II block?
Large doses (>10 times ED95)
prolonged (>30 minutes) exposure
presence of abnormal (atypical) plasma cholinesterases (pseudocholinesterase/butyrylcholinesterase deficiency)
What is the ED95 and DUR25 of succ?
ED95 0.3mg/kg
DUR25 10-12 min
What are risks of Succ, specifically in children?
Bradycardia and Asystole
Most effective treatment to prevent myalgia (other than Non-depolarizing agents)
NSAIDS
Pediatric myotonias and dystrophies should never received which NMBA?
Succ
Associated with hyperkalemia and rhabdo
In peds succ should only be used in emergency intubation
Initiation dose of succ in
Adults
Children
Infants
1 mg/kg
1.5-2 mg/kg
3 mg/kg
-Curonium
Aminosteroids
-Acurium
Benzylisoquinolinium
What does an ETCO2 alpha angle greater than 90 indicate?
V/Q mismatch
What is phase 1 of ETCO2 tracing?
Flat beginning of expiration, dead space air escaping
What is phase II of ETCO2 tracing?
Sharp upslope as CO2 rich air from alveoli is expired
If it’s slanted it means there’s something blocking expiration, either in the tube (Valve issue or kink) or the lungs (COPD, emphysema, air entrainment from asthma)
What is phase III of ETCO2 tracing?
Plateau
Usually slightly upward since the deepest areas of the lung have the highest cocentration of CO2 exchange
What does an ETCO2 B angle greater than 90 indicate?
Malfunctioning inspiratory unidirectional valves
rebreathing
low-tidal volume with a rapid respiratory rate
Andrews Table
Abdomen hangs free
Prevents epidural hemorrhage
Causes of vision loss (5)
central retinal vein occlusion
glycine toxicity
ischemic optic neuropathy
sentinel retinal artery occlusion
cortical blindness
Which has a better chance of recovery: sensory or motor deficits?
Sensory
When do sensory deficits usually resolve?
Within 5 days
If it lasts longer, contact neurologist
What should you do if the patient has a motor deficit?
Contact neurology right away
What nerves are included in the brachial plexus?
axillary
radial
median
musculocutaneous
ulnar
Second most common cause of PNI across anesthesia types
Brachial Plexus injury
What are the manifestations of a radial nerve injury?
Inability to:
Abduct thumb
Extend wrist
extend metacarpals
What is the single greatest predictor of a difficult airway in an obese patient
Neck circumference > 40cm
Common Peroneal injury primarily manifests as
Foot drop
What nerve injury is associated with a difficult forceps delivery?
Obturator
What damage can occur from a jaw thrust manuever?
Facial nerve damage from compression of the ascending ramus
What are the top three leads you should monitor if the pre-op 12 lead is normal?
III, V3, V4
What is the TOFR for full reversal?
0.9
What is the treatment for Myasthenia Gravis?
Anticholinesterases, IVIG, Thymus removal
What are some clinical considerations for patients with sickle cell disease?
- High incidence of Vaso-occlusive crisis (VOC) and Acute Chest Syndrome (ACS)
- MUST remain well oxygenated at all times
- Avoid tourniquets wherever possible
- Avoid narcotics as much as possible
What are some systemic complications of scleroderma?
80% develop ILD leading to pHTN and RV failure!!!
Renal dysfunction
Decreased GI motility
May need invasive cardia monitoring intraop
