AP 1 Final Flashcards
The National Library of Medicine notes people as “elderly” if they are between what ages?
65-79
For those over the age of 80, what is the terminology used to describe the patients age?
AGED, 80 AND OLDER
How many people in the United States reach the age of 65 every day
10,000
By 2030, what percentage of the US population will be 65 or older
20%
Patients older than 65 account for what percentage of hospital stays across the country
43%
What type of neurologic problems are patients at increased risk for during the post-operative period?
CVA (stroke), post-op delerium, over narcotization, drug-drug interactions (particularly with anti-cholinergic side effects)
What is the ASA recommendation for when mental status of the patient should be assessed?
Periodically during emergence and recovery
What does NSQIP stand for
National Surgical Quality Improvement Project
What types of surgeries does NSQIP EXclude?
NSQIP excludes cardiac, carotid, and neurologic procedures
NSQIP states that for ages over __, odds ratio of a CVA is __
62, 3.9
If a perioperative stroke occurs in an eldery patient, it is associated with an _______ increase in 30 day mortality
8-fold
Patients with a history of what 2 problems are at highest risk for peri-operative CVA?
Prior CVA and Renal Failure
What is the definition of an odds ratio
The likeliness of an event occurring if exposed to a given variable
In an adjusted odds ratio when taking into account other variables, what is the greatest predictor of peri-operative stroke?
Age
What are the guidelines from the Emory Comprehensive Stroke Center regarding neurologic exams in high-risk patients?
- q15min neuro exams x 4, q30min neuro exams x 2
- USE A SCREENING TOOL: FAST (Face, Arm, Speech, Time)
- Don’t hesitate to call an anesthesiologist/surgeon to the bedside or activate a STROKE TEAM
What 2 things can we as anesthesists do to monitor neurologic function in high risk patients?
Frequent neuro exams and control blood pressure
In a perioperative setting, what percentage of decline from baseline blood pressure is associated with stroke?
20%
Should we manage BP based on a percentage of the patient’s baseline or the absolute number of the patient’s baseline?
Percentage
Most BP recommendations suggest keeping within 15-20% of ____ ____ ____
Mean Arterial Pressure
In eldery patients, an episode of delirium in the hospital increases the risk of what 3 things?
Longer hospital stay, persistent cognitive decline, placement in nursing home
What is the incidence of delirium in the PACU in elderly (age > 70) patients?
Up to 45% of patients >70
What are the risk factors for post-operative delirium?
Age > 70 (OR 3.4) Age > 80 (OR 5.2) Psychiatric/Neurodegenerative disorders (OR 4.2) Current alchol abuse (OR 6.5) COPA/OSA
What factors associated with increased risk for post-op delirium do we have control over correcting?
Dehydration, abnormal electrolytes, anemia, dysglycemia
What are 4 anesthetic risk factors for post-op delirium?
Pre-op benzodiazepines, ASA III-IV, fluid fasting > 6 hrs, anticholinergic drug use
What are 7 surgical/OR risk factors for post-op delirium?
Hip replacement, abdominal aortic aneurysm repair, neurosurgical procedure, CT surgery, blood loss, intraop hypothermia, intraop hypotension
What is the incidence of post-op delirium in hip replacement surgeries?
37%
What are the symptoms of HYPERactive delirium?
Agitation, hallucinations, disorientation
Why is HYPOactive delirium usually missed in the PACU?
It is subtle, the pt could be cooperative, many pts are asleep or resting
What are 4 treatments of post-op delirium?
- Behavioral/environment interventions
- Dexmedetomidine
- Haldol
- Possibly Risperidone/Olanzapine
What is the dose and frequency of Haldol to treat post op delirium
1-2mg IV, may repeat every 15 minutes
When is the only time you should treat post-op delirium with a benzodiazepienes
In the case of suspected alcohol withdrawal
What are some reasons that elderly patients are at higher risk for post-op delirium and pain?
1) Organ changes may compromise renal or liver funtion
2) Liver mass decreases with age and can limit metabolism of drugs
3) Increased body fat causes longer time of action for lipophilic drugs like fentanyl
4) Kidney mass decreases up to 60%
5) Decreased water in the body so hydrophilic drugs have a more profound effect
Dose reduction of opioids while treating post-op pain is appropriate to both treat pain and still avoid unwanted effects of pain meds. What are the reduced bolus doses of morphine, fentanyl, and hydromorphone?
Morphine - 1-2mg IV
Fentanyl - 25mcg
Hydromorphone - 0.2mg
What is the dose of acetaminophen when using it is a non-narcotic adjunct to treat pain?
1gm IV
What is the max daily dose of acetaminophen?
4 grams
What is the max daily dose of Ketorolac in patients over 65?
60mg IV or IM
You should avoid Ketorolac in patients with what comorbidity?
Severe renal impairment
What must a patients CrCl value be in order to be classified as having severe renal impairment?
Less than 45ml/min
Ketorolac is contraindicated in patients with what 2 complications
1) Active peptic ulcer disease
2) Recent GI bleed
What doses of iv ibuprofen (NSAID) are used for post-op analgesia to decrease opioid requirements
400-800mg
What is the range of doses for IV Diclofenac aka Dyloject (NSAID)
3.75-75mg
What is the recommended dose for Diclofenac
37.5mg IV
What is the recommended dose for Diclofenac for elderly
18.75mg IV
What advantage does IV Diclofenac have over ketolorac or aspirin?
Significantly less disruption of platelet function
What type of drug is Tramadol
Weak opioid agonist with tricyclic anti-depressant properties
What is the onset time for oral Tramadol
One hour
What is the peak time for oral Tramadol
2-4 hours
When is Tramadol contraindicated
In patients with renal disease and seizure disorders
What is the initial dose of Tramadol
50-100mg
What channels does Gabapentin work on that creates its analgesic properties
Alpha2delta subunit of calcium channels
How is the Gabapentin excreted
Renally
What is the starting dose of Gabapentin
300-400mg po
What do patients with CAD have a risk of post-operatively?
Tachycardia
What is the percent chance for both men and women of developing CAD after age 40?
49% for men, 32% women
What is the incidence of post-op cardiac intervention in patients with stable angina
22%
What is tachycardia a significant risk for in patients with CAD?
Ischemia
What is the J point on an EKG
Where the QRS ends and ST segment begins
Where should ST elevation be measured?
From the upper edge of the PR segment to the upper edge of the ST segment
What is the most common post-operative dysrrythmia?
Atrial fibrillation
What are the 4 risk factors for atrial fibrillation?
1) Cardiac surgery
2) Thoracic surgery
3) Age
4) Male
Loss of atrial contraction can increase what
Pulmonary pressures and pulmonary edema
A-fib can lead to what 3 poor outcomes
1) Increased risk of stroke
2) Increased hospital length of stay by 2 days
3) Increased mortality
What 4 things can we do to prevent a-fib
1) Check and correct abnormal electrolytes
2) Treat hypotension
3) Be watchful of hypervolemia in high risk patients (dialysis, CHF)
4) Monitor respiratory status (hypercarbia/hypoxia)
What is the electric cardioversion treatment for unstable a-fib
50-100 J sync
What is the pharmacologic therapy for unstable a-fib
Amiodarone load + drop
What is a pharmacologic therapy for rate control with stable a-fib
Diltiazem IV
What is the target HR for stable a-fib in the immediate period
80-100bpm
What is a pharmacologic treatment for stable a-fib if the patient has CAD
Beta blocker
What 3 hemodynamic changes can decrease preload
1) Hypovolemia
2) Increased venous capacitance (due to regional anesthesia)
3) Increased intrathoracic/cardiac pressure
What 2 hemodynamic changes cause decreased cardiac function
1) Decreased stroke volume
2) Change in HR/rhythm
What 3 things can cause decreased afterload (SVR)
1) Sepsis
2) Anaphylaxis (also affects preload)
3) Residual medication/anesthetic effect
What are 6 causes of hypertension in the PACU?
1) Pain
2) Hypercapnia
3) Urinary retention
4) Pre-existing HTN
5) Hypervolemia
6) Increased ICP
Almost 90% of patients in the PACU who will become hypertensive do so within what amount of time
1 hour
50% of patients who develop HTN in the PACU will do so within what amount of time
15 minutes
What fraction of major PACU complications are respiratory
2/3
What are the 3 most common respiratory issues in the PACU
Hypoxia, hypercarbia, aspiration
All anesthetic drugs cause a dose dependent reduction in minute ventilation except which 2 drugs
Ketamine and N2O
Which part of the minute ventilation equation do opioids affect
Rate - they reduce rate
Which part of the minute ventilation equation do volatile agents
Volume - they reduce volume
Which part of the minute ventilation equation does propofol effect
Both rate and volume
What effects can hypercapnia have on heart rate, heart function, and neurologic function
Tachycardia, arrhythmias, htn headache, confusion, tremor, coma
Where are peripheral receptors that detect PaCO2 located
Carotid bodies
Where are central receptors that detect PaCO2 located
Medulla
How is ventilation affected by a rise in PaCO2
Linear increase in ventilation with increase in PaCO2
Ventilatory response to ___ is reduced by almost all anesthetics
CO2
What effect does supine positioning, laparoscopic procedures, obesity, and atelectasis have on FRC
Decrease
What happens to closing capacity of airways under anesthesia
Increase
What aspects of the lung change with age
Lung volumes and elasticity
Geriatric patients have an elevated risk of developing what 2 lung problems
Atelectasis
Pneumonia
Deep breathing has not shown to be beneficial in the post-op setting except with what population
Elderly populations, they are benefited with greater pulmonary recovery and prevention of pneumonia
What part of the airway does airway obstruction almost always occur in
Pharyngeal
Are men or women more at risk for OSA
Men
Are post-menopausal or pre-menopausal women more at risk for OSA
Post-menopausal
What jaw problems increase risk for OSA
Micrognathia and retrognathia
Patients with a neck circumference greater than __cm are at risk for OSA
40cm
What is the definition of OSA
Repetitive episodes of upper airway partial/complete obstruction during sleep that are accompanied by sleep disruption, changes in air flow and hypoxemia.
What are the 2 parts of the oropharynx
Palatopharynx (velopharynx) - length of soft palate to the tongue
Glossopharynx - below base of tongue
What is the action of the genioglossus muscle
Depress and protrude the tongue
What nerve innervates the genioglossus muscle
Hypoglossal (12)
After 60 minutes of anesthesia, you should make sure the patients respiratory rate is over
8 breaths/min
After 60 minutes of anesthesia, check for apneic episodes over __sec
10
After 60 minutes of anesthesia, check for SaO2 over ___% on room air
90
What are risk factors for residual NMB
Patient distress, upper airway obstruction, aspiration, hypoxemia, impaired ventilation, re-intubation
What was the NMB agent used in 99% of residual NMB cases
Rocuronium
What percentage of elderly patients are affected by dysphagia
15%
Why are elderly patients more at risk for dysphagia
Muscle mass decreases with age and swallow reflex loses strength
In eldery patients with concomitant neurological disease, the percentage with dysphagia rises to
50%
What are diseases/conditions that increase risk of oropharyngeal dysphagia?
Alzheimers, tumors, myasthenia gravis, ALS, Parkinson’s, achalasia, dementia, history of CVA
High risk patients should have an HOB greater than ____
30 degrees
What types of drugs should you minimize in patients at risk for dysphagia
Sedatives and opioids, helps limit pharyngeal motor dysfunction
What exam can be performed in the PACU to screen for dysphagia
3oz swallow challenge
Does the ASA recommend we monitor for urine output in all patients?
No, just select patients
What is the biggest risk factor for POUR
Age
What surgeries increase risk for POUR
Inguinal hernia repair, colorectal/anorectal, pelvic, hip surgeries
What type of drug increases risk of POUR
Opioids
Is POUR a risk factor for post op delirium?
Yes
How is hypothermia defined in Dr. Duggan’s lecture
Less than 36 degrees celsius
What are predictors of hypothermia
Age, duration of anesthesia, pain, risk score of CAD, CVA, insulin dependent DM, renal failure
A 1.9 degree drop in temperature increases risk of WI by?
20%
How does hypothermia affect the incidence of cardiac events
a. Doubles
b. Triples
c. Quadruples
b. Triples
What effect does hypothermia have on the blood
Impairs platelet function, decreases fibrinogen, disturbs coagulation enzymes, coagulopathy
Why does a 1.9 degree drop in temp increase risk of WI
Impairs antibody and cell-mediated defenses, decreases o2 delivery to peripheral tissues
Active warming reduces the time taken to achieve normothermia by how much in comparison to warming blankets
30 minutes
Active warming was found to reduce mean time taken to achieve normothermia by how much in comparison to unwarmed blankets
90 minutes
What is the difference in shivering of patients who were actively warmed vs. those who were passively warmed
There is no difference
What are the triggering agents for MH
Sux, volatile agents (except N2O)
What kind of disorder is MH
Pharmacogenetic
MH is caused by the abnormal handling of what element in skeletal muscle
Intracellular calcium
What is the mortality rate from MH using MH Hot Line in the hospital
7%
What is the mortality rate from MH using MH Hot Line outside the hospital
20%
MH is normally a defect in what receptor
Ryanodine
What is the effect of MH triggers on Ca2+ release
Triggers uncontrolled calcium (Ca2+) release from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RYR1) causing a rapid and sustained rise in myoplasmic Ca2+. The high intracellular Ca2+ activates Ca2+ pumps at the SR and the sarcolemma to reuptake calcium into SR or to transport it into the extracellular space respectively. The energetic cost to regain cellular Ca2+ control causes a need for ATP, which in turn produces heat.
How does O2 consumption change with MH
3-5 times the normal O2 consumption
How does PaO2 change during MH
142 +/- 10 mmHg
How does PvO2 change during MH
36 +/- 4 mmHg
How does PaCO2 change during MH
54 +/- 4 mmHg
How does PvCO2 change during MH
107 +/- 10 mmHg
When is the onset of MH explosive?
During induction
When is the onset of MH insidious?
Maintenance, postop
Do all patients with MH outbreak have muscle rigidity?
No
What is an early sign of MH outbreak?
Unexplained increased etCO2
What is a late sign of MH outbreak?
Temperature
Does MH cause respiratory/metabolic alkalosis or acidosis?
Acidosis
Is hyperthermia an early, intermediate, or late sign of MH?
Late
Is venous cyanosis an early, intermediate, or late sign of MH?
Late
Is MMR an early, intermediate, or late sign of MH?
Early
Hyperthermia was the 1st sign of MH in what fraction of patients
1/3
What are the main causes of death within the first few hours of MH manifestation
Hyperkalemia, v-fib
What are the main causes of death within several hours of MH manifestation
Pulmonary edema, acid/base abnormalities, electrolyte imbalance, coagulopathy
A high incidence of disseminated intravascular coagulopathy occured when temperatures were above
41.5 degrees celcius
What are the main causes of death days after MH manifestation
Multi-organ failure, brain damage, renal decompensation
What 2 diseases associated with MH are due to a mutation with Ca2+ release via muscle isoform ryanodine receptor RYR 1 gene (Chromosome 12q13)
Central Core Disease
King-Denborough Syndrome
What disease associated with MH is due to a mutation with Excitation-Contraction Coupling Protein on STAC3 Gene (Chromosome 12q13.13)
Native American Myopathy (NAME)
What 2 diseases associated with MH are due to a mutation in the Ca2+ channel voltage dependent 1S subunit CACNA1S (Chromosome 1q32)
Hypokalemic periodic paralysis
Multiminicore Disease
What disease/symptom that is possibly associated with MH is caused by an RYR1 mutation
Exertional heat stroke
What disease that is possibly associate with MH is found in patients that were CHCT + and had an RYR1 mutation
Exercise induced rhabdomyolysis
What deficiency is possibly associated with MH
Carnitine palmitoyl transferase
What are some differential diagnoses associated with MH
NMS Hypoxic encephalopathy Ionic contrast agents in CSF Baclofen withdrawl Amphetamine toxicity Cocaine toxicity ETOH withdrawal Myopathy /rhabdomyolysis with Statins Hypoxia Iatrogenic overheating Transfusion reaction Thyrotoxicosis Pheochromocytoma Anticholinergic syndrome
What is the first thing you should do if you suspect MH
Stop all volatile agents/sux
After stopping volatile agents/sux, what should you do in cases with suspected MH manifestation
- Call for assistance
- Hyperventilate with 100% O2 and flows over 10L/min
- Communication/halt procedure
- Give dantrolene
Whats the dose of Dantrolene
2.5mg/kg
How should you dilute a 20mg bottle of Dantrolone
Dissolve with 60ml sterile water, each bottle has 3gm mannitol
What are some side effects of Dantrolene
Cardiac arrest, thrombophlebitis (pH 9), synergistic action with NMB
After Dantrolene, what should you begin to treat
Hyperkalemia, arrythmias, hyperthermia, electrolyte imbalances
What is the endpoint of the treatment of hyperthermia
38 degrees celsius
What should you keep the UOP at
Greater than 2cc/kg/hr
What is the Dantrolene dosage/frequency for post-acute phase therapy
1) 1mg/kg IV every 4-6 hours OR 0.25mg/kg/hr - give for 24-36 hrs
2) After step 1, oral Dantrolene 1mg/kg every 6 hours for the next 24 hours
What tests/electrolyte levels should you check to watch for signs of recrudescence, myoglobinuria, renal failure, DIC
ABG, CPK, K+, Ca+, urine/serum myoglobin, clotting
How often should you check ABG/CPK/K+/Ca+/etc. for post-acute phase therapy
Every 6 hours until normal and stable
How long should you observe MH patients in the ICU
24-48 hours
Where should you refer patient and families for counseling
MHAUS
Children less than __ years old who experience a sudden cardiac arrest after sux, in the absence of hypoxia, should be treated for what first?
9 years old, acute hyperkalemia
What test is indicated with family or personal history of MH or MH-like events
Halothane-Caffeine Contracture Test
What are the contraindications for the Halothane-Caffeine Contracture Test?
Age less than 4 years old (20kg), less than 3 months from the event
How should you prepare the anesthesia machine for an MH susceptible patient
- New fresh gas outlet hose and circle system tubing
- Remove vaporizers
- Flush system with >10L/min O2 for 10 min
- Flush for 20min if fresh gas can’t be replaced
What should you have in or near the OR when you have an MH susceptible patient
MH cart
What type of temperature should be monitored in an MH susceptible patient
Core temp
When should Dantrolene be given as a pre-med
Cases of stress-induced MH
How often should you monitor RR, BP, HR, temp in the PACU with an MH susceptible patient
every 15 minutes for 1 hour
What vitals/tests should be monitored on an MH susceptible patient in Phase II of PACU
Pulse ox, urine color, HR, temp, and BP every 30 min for at least 1.5 hours
What muscle often becomes rigid during MH manifestation
Masseter
What are early signs of MH outbreak
Increased CO2, increase HR, resp/met acidosis, venous desaturation, masseter rigidity, electrolyte imbalance
Halstead and Hall injected what anesthetic into peripheral sites in the 1880’s
Cocaine
In 1885, Corning used what device to arrest local circulation and prolong the block
Esmarch tourniquet
What did Braun invent in 1903
Chemical tourniquet
Who wrote the definitive text on regional anesthesia in 1920
Labat - Regional Anesthesia: Its Technique and Application
What are 3 risks of regional anesthesia
Nerve injury, LA toxicity, site specific risks
What are 4 contraindications of regional anesthesia
Uncooperative, coagulopathy, infection, LA allergy
What are hypoechoic structures and how do they appear on an ultrasound
Structures through which sound passes easily, appear dark or black
What are hyperechoic structures and how do they appear on an ultrasound
Structures reflecting more sound waves, appear white
High frequency waves have ______ resolution but _____ tissue penetration when compared to low frequency waves
Higher resolution, poorer tissue penetration
Low frequency sound waves have _____ resolution but _____ tissue penetration when compared to high frequency sound waves
Poorer resolution, better tissue penetration
Is low frequency better for shallow or deep structures
Deep structures
What type of probe is better for shallow structures
Linear
When is the needle best seen with a linear probe
When its perpendicular to the transducer and parallel to the surface
What probe/needle angle is best for deeper structures
Low resolution curvilinear probe, steeper needle angle
What does an In Plane technique look like
Needle inserted from the side of the transducer
What does an Out of Plane technique look like
Needle inserted at the front side of the transducer, midline
What 4 blocks block portions of the brachial plexus
1) Interscalene
2) Supraclavicular
3) Intraclavicular
4) Axillary
The cervical plexus is derived from what spinal nerves
C1-C4
Cervical plexus supplies branches to what 2 muscle groups
Prevertebral muscles, strap muscles of the neck
The cervical plexus supplies branches to what nerve
Phrenic nerve
What are some examples of surgeries where cervical plexus blocks are useful
Lymph node dissections, plastic repairs, carotid endarterectomy
Bilateral cervical plexus blocks are used for what surgeries
Tracheostomy, thyroidectomy
What is an advantage of the cervical plexus block
The ability to monitor the awake patient’s neurologic status continuously
What are some complications and side effects of cervical plexus blocks
Intravascular injection, blockage of phrenic nerve and SLN, spread of anesthetic into epidural and subarachnoid spaces
Nerve roots of musculocutaneous nerve
C5-C7
Nerve roots of axillary nerve
C5-C6
Nerve roots of radial nerve
C5-T1
Nerve roots of median nerve
C5-T1
Nerve roots of ulnar nerve
C8-T1
What cord innervates musculocutaneous nerve
Lateral
What cords innervate median nerve
Lateral and medial
What cord innervates ulnar narve
Medial
What cord innervates radial nerve
Posterior
What type of surgeries are interscalene blocks indicated for
Shoulder and upper arm surgeries
What type of surgeries need an interscalene block to be supplemented with an ulnar nerve block
Forearm and hand surgeries
What are some complications of interscalene blocks
Ipsilateral phrenic nerve block, vagus/RLN/cervical sympathetic nerves can be blocked, PTX
What trunk levels does the interscalene block occur at
Superior and middle trunks
What dermatomes is the interscalene block most intense at
C5-C7
What dermatomes is the interscalene block least intense at
C8-T1
What types of surgeries are supraclavicular blocks indicated for
Elbow, forearm, hand
What trunk level do supraclavicular blocks occur at
Distal trunk-proximal division
What are some complications of supraclavicular blocks
PTX, phrenic nerve block, Horners syndrome
What are symptoms of Horners syndrome
Ptosis, miosis, anhydrosis
What surgeries are infraclavicular blocks used for
Arm and hand
What level do infraclavicular blocks block
At the level of the cords, arranged around axillary artery
Relative to supraclavicular blocks, what do infraclavicular blocks have less of a risk for
Pneumothorax
Are the shoulder and upper arm anesthesized with an infraclavicular block?
No
Axillary blocks are useful for what type of surgeries
Forearm and hand
What level does an axillary blockade occur at
Terminal nerve branches
What are some complications of axillary blocks
Nerve injury, systemic toxicity, hematoma, infection
Why are multiple injections needed for an axillary block
The nerves are separated by fascia
Where is an axillary block more intense
C7-T1 (ulnar nerve)
What are the 5 types of terminal nerve blocks
Median, ulnar, radial, musculocutaenous, digits
What cords are blocked with a terminal nerve block of the median nerve
Lateral and medial cords
What cords are blocked with a terminal nerve block of the ulnar nerve
Medial cord
What cords are blocked with a terminal nerve block of the radial nerve
Posterior cord
What drug do you not use with a terminal nerve block of the digits
Epi
Are Bier Blocks useful for short or long procedures
Short
What are the benefits of a Bier Block
Easy to administer, rapid onset
What is the dose and concentration of Lidocaine needed for a Bier Block
25-50 ml of 0.5% Lidocaine
What type of tourniquet is used for a Bier Block
Pneumatic
What is an example of a surgery that would use a Bier Block
Carpal tunnel (45-60min)
Tourniquet pain occurs after how long
20-30min
The tourniquet must be up for at least 15-20 min to reduce risk of what
Rapid bolus of local anesthetic and systemic toxicity
What are some complications of a Bier Block
Phlebitis, compartment syndrome, loss of limb
What are the nerve roots of the femoral nerve
L2-L4
What are the nerve roots of the obturator nerve
L2-L4
What are the nerve roots of the lateral femoral nerve
L1-L3
What are the nerve roots of the sciatic nerve
L4-S3
What 3 nerves are part of the lumbar plexus
Femoral, obturator, lateral femoral
The lumbar plexus lies within what muscle
Psoas
The 2 nerves are continuations of the sciatic nerve
Common peroneal and tibial
What type of surgeries are femoral nerve blocks useful for
Anterior thigh, knee, medial foot
Why are femoral nerve blocks used for knee surgery
Post op pain control
What are some examples of surgeries that call for a femoral nerve block
Patellar surgery, knee scopes, skin grafting
What groups of muscles/nerves does the femoral nerve innervate
Hip flexors, knee extensors, sensory of hip and thigh
Can a femoral nerve block provide surgical anesthesia by itself?
No
Where is a femoral nerve block placed?
Below the inguinal ligament
An obturator nerve block provides anesthesia to what region
Medial thigh
An obturator nerve block provides muscle relaxation to what muscles
Adductor muscles of the hip
An obturator nerve block is used in combination with what 2 blocks
Femoral and sciatic
For complete anesthesia of the knee, what block do you need
Obturator
A sciatic nerve block provides sensory anesthesia to which areas
Posterior hip, knee, and low extremity
A sciatic nerve block provides a motor block to what muscles
Hamstrings and low muscles
A sciatic nerve block is useful for what type of surgeries
Knee, calf, achilles tendon, foot, ankle
A sciatic nerve block is used for post op pain control in what surgeries
Knee, posterior knee
A popliteal block is useful for what surgeries
Foot and ankle
What muscles are spared in a popliteal nerve block
Hamstrings
What 5 nerves are involved in an ankle block
Superficial peroneal, deep peroneal, saphenous, tibial, sural
What type of surgeries are ankle blocks used for
Foot surgeries
What drug cannot be used with ankle blocks
Epi
How many injections are required for an ankle block
5
Area innervated by sural nerve
Posteror lateral leg below the knee
Area innervated by saphenous nerve
Medial leg below the knee
Area innervated by superficial peroneal nerve
Anterior lateral leg below the knee, top of foot except small region between 1st and 2nd toe
Area innervated by deep peroneal nerve
Region between 1st and 2nd toe on top of foot
What nerves does a lumbar plexus (psoas) block include
Lateral femoral cutaneous, femoral, obturator
What area does the lumbar plexus block provide complete analgesia for
Total hip and total knee
What type of needle is required for lumbar plexus block
Long needle
What is another name for a lumbar plexus block
Psoas
The saphenous nerve is a terminal extension of what nerve
Femoral
Saphenous nerve block blocks sensory innervation of what area
Medial aspect of lower leg
Is saphenous nerve block an isolated block?
No
Saphenous block is used with what other block to achieve complete analgesia in what region
Sciatic, Below the knee
Clinical activity of local anesthetics (LA) are based on what 3 physiochemical properties
- Lipid solubility
- Ionization
- Protein binding
Lipid solubility deals what 2 aspects of LAs
Duration of action and potency
How does increased lipid solubility affect duration of action and potency
Increased lipid solubility=increased duration and increased potency
What 3 LAs have the highest degree of protein binding
Tetracaine > Bupivacaine > Ropivacaine
What aspect of LAs does ionization affect
Speed of onset
How is speed of onset affected if pH of a solution is close to the pKa
Speed of onset is increased
LAs affect what channels
Na+ channels
List the pKas of Mepivicaine, Lidocaine, Bupivicaine, Ropivicaine
7.6, 7.9, 8.1, 8.1
How does infected tissue affect the speed of onset of LAs
Decreased pH in infected tissues, more LA will be in the charged, hydrophilic form and not cross to the Na+ channels - so decreased speed of onset
Do LAs with Epi have a higher or lower pH
Lower, so it takes longer to cross the cell membrane and bind to Na+ channels
What part of the LA crosses the cell membrane
The unbound fraction
How does increased lipid solubility and duration of action affect protein binding
Increase protein binding
What 2 proteins bind LAs
Albumin, alpha acid glycoprotein
How does decreased pH affect protein binding
Decreased pH=decreased protein binding=more unbound LA, risk of toxicity
Where are amides metabolized
Liver
What LAs are in the amide class
Bupivacaine, Lidocaine, Mepivacaine, Prilocaine, Ropivacaine
What are the longest acting amide LAs?
Bupivacaine, Ropivacaine (1.5-8hrs)
Duration of Lidocaine
0.75-2hrs
Duration of Mepivacaine
1-2hr
Duration of Prilocaine
0.5-1hr
What enzyme are esters metabolized by
Pseudocholinesterase
What LAs are esters
Benzocaine, Chloroprocaine, Cocaine, Procaine (Novocaine), Tetracaine
All esters have a duration of 0.5-1hr except which one?
Tetracaine - 1.5-6hr
What is a complication of benzocaine
Methemoglobinemia - decreases ability of hemoglobin to carry o2
What are 3 major risks of nerve blocks
Systemic toxicity, infection, peripheral nerve damage
Which needles decrease the risk for peripheral nerve damage
B bevel needles (short bevel)
What 6 things determine risk of LAST
- Site of injection
- Which LA used
- Dose
- Degree of protein binding
- Degree of acidosis
- Epinephrine?
How does epinephrine affect local anesthetic affect
Slows the rate of absorption via vasoconstriction
Peak blood concentrations of LA depend on what
Site of injection
Absorption of LA is related to _______ of injection site
Vascularity
List injection sites from most to least vascular
Tracheal > intercostal > caudal > epidural > brachial plexus > femoral/sciatic > subcutaneous
What is the 1st stage of LAST on the CNS
CNS excitation
What pathways are blocked during CNS excitation due to LAST
Inhibitory
What are symptoms of LAST during CNS excitation (phase 1)
Dizziness, tinnitis, circumoral numbness, muscle twitches, slurred speech, seizures
What is the 2nd stage of LAST on the CNS
CNS depression
What pathways are blocked during CNS depression due to LAST
Inhibitory and excitatory pathways
What are the symptoms of LAST during CNS depression (phase 2)
Respiratory depression, obtundation, coma
What are cardiovascular signs of LAST
Depress myocardial conduction/contractility, arterial vasodilation, hypotension, bradycardia, VT or VA, AV block, PVCs, PACs
Whats the only local anesthetic that doesn’t produce arterial vasodilation
Cocaine
Which local anesthetic avidly blocks cardiac Na+ channels and has a high degree of protein binding, thus making resuscitation difficult
Bupivacaine
What are some methods for prevention of LAST
Incremental injection, frequent aspiration, adding a marker, limiting LA dose/concentration, communicate w/ patient
What is a good marker for preventing LAST
Epi - 5mcg/ml
Patients with which 3 conditions should we proceed with caution when administering local anesthetics
Cardiac conduction problems, kidney/liver disease, acidosis (increases free LA)
In what 2 ways does epinephrine improve the quality of the block
Increased neuronal uptake, alpha 2 adrenergic receptor
By what percent does HR increase with epinephrine
20%
Epinephrine decreases absorption/prolongs action of what types of local anesthetics
short acting LAs like lidocaine and mepivacaine
What amount of epinephrine is normally added to Las
5mcg/ml (1:200,000), 2.5mcg/ml (1:400,000)
What are 3 pharmacologic treatment options for seizures due to LAST
Midazolam, propofol, thiopental
What are treatments for cardiac toxicity/respiratory depression due to LAST
Manage airway, ACLS/BLS (avoid B blockers, Ca+ blockers, lidocaine), IV lipid infusion, cardiopulmonary bypass
What drug is used as a lipid treatment for LAST
20% intralipid
What is the per kilo dose for a bolus of Intralipid
1.5ml/kg
What is the per kilo dose for Intralipid after the inital bolus
0.25ml/kg/min for 30-60min
How many times can a bolus of Intralipid be repeated for persistent cardiac collapse
1-2 times
Infusion rate of Intralipid could be increased if what declines
Blood pressure
What is used during the placement of nerve blocks to test motor response
Peripheral nerve stimulator
What is used during the placement of nerve blocks to test sensory response
Paresthesia technique
What are the roots of the brachial plexus
Ventral rami
Where are the supraclavicular nerves
Cape of the neck, anteriorly to second rib, top of the scapula
The intercostobrachial nerve is at what vertebral level
T2
Which block provides analgesia for shoulder, humerus, clavicle
Interscalene block
Where is an interscalene block performed
At the level of the roots/trunks of brachial plexus, between anterior and middle scalene muscle
What are adverse effects and possible complications associated with interscalene blocks
Phrenic nerve palsy, Horner’s syndrome, cervical plexus block, RLN palsy, vertebral artery injection, pneumothorax, epidural/spinal injection
What is caused from an inadvertant block of the recurrent laryngeal nerve
Hoarseness
How many ccs of LA injected into the vertebral artery can lead to seizures
1-3mL
What is the most common adverse event following an interscalene block
Phrenic nerve palsy
What is referred to as the “spinal of the arm”
Supraclavicular block
What block is performed at the level of the divisions of the brachial plexus
Supraclavicular block
What block is indicated for surgeries of the entire arm, below the level of the shoulder
Supraclavicular block
What risks associated with supraclavicular blocks
Pneumothorax, phrenic nerve palsy, Horner’s syndrome, RLN block, vascular puncture
What block is indicated for surgeries involving the elbow, forearm, and hand
Infraclavicular
What block deals with nerve cords situated around the axillary artery
Infraclavicular
What are complications associated with infraclavicular blocks
Vascular puncture, pneumothorax
What block is indicated for surgeries involving the elbow, forearm, and hand and is performed at the terminal branches of the medial, ulnar, radial, and musculocutaneous nerves?
Axillary
What are complications associated with axillary blocks
Infection, hematoma
The arm must be in what position for an axillary block
Abducted
Since an axillary block is transarterial, what adjuncts should be used during insertion
Peripheral nerve stimulator, ultrasound
Which nerve of the brachial is the most difficult to locate
Radial
Blocking the ulnar nerve provides good analgesia for which finger
5th digit
Bier Blocks provide anesthesia for surgeries lasting how long
45-60 minutes
What block is used for short surgeries of the forearm, hand, or leg
Bier block
What type of tourniquet and bandage is required for a bier block
Double pneumatic tourniqet, eschmark elastic bandage
What dose/concentration of lidocaine is needed for a bier block
50mL 0.5% lidocaine
The lumbar plexus is comprised of the _____ _____ of vertebral levels ___ - ___
ventral rami, L1-L4
What are the 4 blocks associated with the lumbar plexus
Iliohypogastric/ilioinguinal
Femoral
Obturator
Lateral femoral cutaneous
The sacral plexus is comprised of the ______ _____ of vertebral levels ____ - ____
ventral rami, L4-S3/S4
The sciatic nerve branches into what 2 nerves
Common peroneal, tibial
Over the last 10 years there has been an increased interest in lower extremity block for what 3 reasons
1) transient neurologic symptoms with spinal anesthesia
2) increased use of thromboembolic prophylaxis
3) evidence of increased early rehabilitation with CPNBs
What nerve block is used for surgeries of the hip, anterior thigh, and knee
Lumbar plexus
A lumbar plexus block covers what 3 nerves
Femoral, lateral femoral, obturator
Whats the distance from skin to lumbar plexus of a deep block
5-10cm
What are complications of lumbar plexus blocks
Renal puncture, spinal or epidural injection, hematoma, LAST
What is the largest branch of the lumbar plexus, that arises from L2-L4
Femoral
What nerve is the posterior division of the femoral nerve and most medial
Saphenous
The posterior division of the femoral nerve is associated with what muscles of the leg
Quadriceps
The articular branches of the femoral nerve feed what parts of the lower extremity
Hip and knee
What nerve is the anterior division of the femoral nerve
Middle cutaneous
What muscle is associated with the anterior division of the femoral nerve
Sartorius
The femoral nerve emerges from what muscle
Psoas muscle
The femoral nerve enters the leg under which ligament
Inguinal
In general, femoral nerve blocks fail if the anesthetic is injected superior to what tissue layer
Fascia iliaca
What types of knee surgery utilize a femoral nerve block
TKA, ACL reconstruction, patellar surgery
What block is used for femoral ORIF, skin grafting, and muscle biopsy surgeries
Femoral
Surgeries involving the medial aspect of the lower leg would use what block
Femoral
What is the largest branch of the femoral nerve
Saphenous nerve
What are the 4 main locations where we can block the saphenous nerve (BAMF)
Below the knee, adductor canal, medial malleolus, femoral
For any surgery involving medial aspect of foot/ankle, what nerve must be blocked
Saphenous
A saphenous block is usually used in conjunction with what other 2 blocks
Popliteal, sciatic
What are the landmarks for a traditional saphenous nerve block
Anterior edge of medial head of gastrocnemius muscle and tibial tuberosity
While traditional techniques all have low success rates for saphenous blocks, what approach has high success
Paravenous
What 4 areas are good for imaging the sciatic nerve
Popliteal, mid-thigh, subgluteal, transgluteal
Which image is hardest to visualize/access the sciatic nerve
Transgluteal b/c of depth
What is the largest nerve in the human body
Sciatic
What nerve provides sensory innervation to the knee, hip, and below the knee (except medial)
Sciatic
The sciatic nerve blocks motor function to what area/muscles
Hamstrings, lower leg below the knee
In which surgeries are sciatic nerve blocks indicated
TKA, foot, ankle
What are some complications associated with sciatic nerve blocks
Partial block, nerve injury
Where is the ultrasound probe placed during a popliteal approach of a sciatic block
Popliteal crease
Where are incomplete sciatic blocks common due to anatomical variations
Popliteal fossa
The sciatic nerve divides into which 2 nerves above the popliteal fossa
Tibial and peroneal
What is the main obstable while doing a subgluteal approach to a sciatic nerve block
Depth of nerve
Where is the palpable groove used in a subgluteal approach to a sciatic block
Just lateral to the upper portion of the biceps femoris muscle
What block is used for foot and toe surgeries
Ankle
What 5 nerves are blocked with an ankle block (DPSSS)
deep peroneal, posterior tibial, sural, sapheous, superfical peroneal
