Lecture 5 Flashcards
What are the four types of regional anesthesia?
- Local infiltration
- Bier Block (IV regional)
- Peripheral nerve blocks (PNB)
- Central block
Who can perform local infiltration anesthesia?
Surgeon, Podiatrist, Dentist
What are the indications for a Bier Block?
Brief procedure of hand/forearm
What is the technique for a Bier Block?
20g IV in hand of operative arm with extension tubing/10 ml syringe, 18-20g IV in nonoperative arm, double pneumatic tourniquet on operative upper arm, elevate arm, esmarch wrap distal to proximal, distal cuff inflated, then proximal, inflate to 250-300 mm hg. Esmarch off-distal cuff deflated.
use lido .5% plain 3mg/kg – 40-50 mL injected slowly into IV
Remove IV
Distal cuff is inflated and proximal is deflated
What is the maximum inflation time for a Bier Block?
2 hours
When can you deflate after the procedure
if less than 20-30 minutes you must wait till 30 and deflate slowly
What are the complications of a Bier Block?
Accidental tourniquet release/leak
What are peripheral nerve blocks (PNB) used for?
Digit, ankle, brachial plexus, nerve (femoral)
What is an epidural block?
Injection of local anesthetic into the epidural space
What does the epidural space contain?
Nerve roots, fat & blood vessels
where is the epidural space?
runs from foramen magnum to sacrococcygeal ligament
What are the two techniques for epidural anesthesia?
Hanging drop,
Loss of resistance (LOR) technique
What is the test dose for epidural anesthesia?
1.5% Lidocaine with Epinephrine 1:200,000 mcq (5 mcq/ml) 3-5 ml total
What indicates intravascular placement during a test dose?
HR increase 20% within 30-60 sec
What indicates subarachnoid placement during a test dose?
Signs of spinal within 3 mins
What are the common epidural anesthetics?
*Chloroprocaine (Nesacaine)- 2-3%
*Lidocaine- 1-2%
*Bupivacaine (Marcaine)- 0.25-0.5%
*Ropivacaine 0.25-1%
What is the dose and duration of Chloroprocaine with and without epi?
Dose- 200-750 mg,
Duration- 45-60 min
Epi- 60-90 minutes
What is the Onset of ALL epidural anesthetics
5-15 minutes
What is the dose and duration of Lidocaine with and without epi?
Dose- 150-300 mg,
Duration- 80-120 min
Epi- 120-180 min
What is the dose and duration of Bupivacaine with and without Epi?
Dose- 50-100 mg,
Duration- 165-225 min
Epi-180-240 min
What is the dose and duration of Ropivacaine with and without Epi?
Dose- 75-250 mg,
Duration- 140-180 min
Epi- 150-200 minutes
What are common epidural additives?
Opioids (morphine, fentanyl, sufentanil), Vasoconstrictors (Clonidine, Epinephrine, Dexmedetomidine)
What is a caudal block?
Type of epidural - space entered through the sacral hiatus, used for blocking sacral roots, usually seen in pediatrics
What is a spinal block?
Injection of local into subarachnoid (SA) space at lower lumbar area
where do inject a spinal
lower lumbar
right at iliac crest (L3-4 interspace)
What are the layers penetrated during a spinal block?
Skin, SQ, supraspinous, interspinous, ligament of flavum, epidural space, dura, subdural space, arachnoid, subarachnoid, pia mater & spinal cord
What are recent advances in regional anesthesia?
Ultrasound guided neuraxial blockade, especially useful in obese patients, scoliosis and previous laminectomy
What are the two types of spinal needles?
Cutting tip (Quincke, Pitkin),
Non-cutting (pencil point tip- Whitacre & Sprotte, rounded bevel tip- Greene)
What is the dose and duration of Tetracaine?
with Epi?
Dose- 8-15 mg,
Duration- 60-120 min
§ With Epinephrine 1:1000 solution (0.1-0.2 ml)- 120-240 min
What is the dose and duration of Chloroprocaine for spinal anesthesia?
WIth Epi?
onset?
Dose- 40-60 mg of 1-3% for short procedures, Duration- 45-60 min
EPI NOT RECOMMENDED
onset 5 minutes
What is the dose and duration of Lidocaine for spinal anesthesia?
With Epi?
Dose- 75-100 mg,
Duration- 60-70 min
Epi-75-100 minutes
what is the percentage of Lido for a spinal?
5% but must dilute to 2.5%
What is the dose and duration of Bupivacaine for spinal anesthesia?
With Epi?
Dose- 12-20 mg,
Duration- 90-110 mins
Epi- up to 150 minutes
What is the dose and duration of Ropivacaine for spinal anesthesia?
With Epi?
Dose- 18-20 mg,
Duration- 140-200 min
Epi- not recommended
What is the dose and duration of Prilocaine?
With Epi?
Onset
Dose- 50-80 mg,
Duration- 60-90 min
Epi- not recommended
onset 10 min
What are common spinal additives?
Opioids (morphine, fentanyl, sufentanil),
Vasoconstrictors (Clonidine, Epinephrine, Dexmedetomidine, Phenylephrine)
How much opioid can you add to a spinal?
preservative free morphine- .25-.3mg
Fentanyl- 10-25 mcg
Sufentanil- 5- 10 mcg
How much Vasoconstrictor can you add to a spinal?
§ Clonidine- 15-150 mcq
§ Epinephrine- 100-200 mcq
§ Dexmedetomidine- 3 mcq
§ Phenylephrine- 2-5 mg
What factors determine the spread of local anesthetics in the SA space?
Controllable: Baricity, Patient position, Dose, Site of injection.
Non-Controllable: Volume, Specific gravity, Patient height, Direction of needle bevel.
What is the effect of mixing locals with sterile H2O?
Hypobaric - moves higher
What is the effect of mixing locals with spinal fluid/NSS?
Isobaric - stays at injection site
What is the effect of mixing locals with dextrose?
Hyperbaric - moves lower because of density
Indications for Spinal Epidural
o Lower extremity/hip procedures
o Lower abdominal, groin, perineum, urologic, rectal, or OB procedures
Absolute contraindications for a spinal/epidural
§ patient refusal
§ known allergy to local anesthetic
§ infection at site-
§ sepsis-
§ uncorrected hypovolemia
§ coagulopathy (platelet count <100,000, PT, aPTT and/or bleeding time twice normal)
§ increased ICP (intracranial mass)-
Relative Contraindications for a spinal/epidural
§ infection peripheral to site
§ neurological disorders-
· MS, spina bifida
§ heparin/ASA
§ severe AS, MS or hypertrophic cardiomyopathy
§ back pain/prior lumbar surgery-
§ hypovolemia
§ difficult airway, full stomach-
§ peripheral neuropathy-
§ uncooperative patient/surgeon
what adverse effect can happen if someone gets an epidural who is on an anticoagulant or antiplatelet
Epidural Hematoma which can cause paralysis
needs surgical decompression within 8 hours
what are the physiological effects of a spinal/epidural
SNS
CV
RR
GI
Thermoregulation
o SNS block- what does that mean?
§ decrease venous return-
§ hypotension secondary to decreased cardiac output, related to a decreased venous return
o CV effects
§ bradycardia (T1-T4)- only about 10-15% incidence
o Respiratory effect
§ intercostal paralysis (inspiration & expiration)
o GI- small, contracted gut and hyperperistalsis
o Thermoregulation- vasodilatation due to sympathetic block- leads to hypothermia (go back to page 17- same info)
MOA of Local Anesthetics
· Prevent depolarization of nerve by blocking Na influx
o block alpha-subunit on the inside of the Na channel when in either active or inactive state
· Prevent increase in membrane permeability to Na leads to inability to depolarize and no action potential
· Channel remains closed until local diffuses away
· Small fibers blocked easier than large fibers
· Onset, potency & duration of action (DOA)
o Onset- related to pKa-
o Potency- lipid solubility-
o DOA- protein binding-
Tell me the order of a Block
o B fibers- preganglionic ANS (3 microns)
o C- sympathetic, temperature, slow pain (dorsal root) (0.3-1.3 microns)
o A
§ Delta- fast pain, touch (2.5 microns)
§ Gamma- skeletal muscle tone (3-6 microns)
§ Beta- touch & pressure (5-12 microns)
§ Alpha- motor & proprioception (12-20 microns)
What are the 2 classes of Locals
amides and esters
Metabolism of Esters
§ 1. Esters- ester link cleaved by plasma pseudocholinesterase
CSF lacks esterase enzyme- spinal injected ester local depends on absorption into blood stream
What are people allergic to in Esters
Para-aminobenzoic acid (PABA) associated with allergic reaction
o Allergy to PABA in suntan lotion
o Allergy to methylparaben which resembles PABA
o Use preservative free drug or an amide
Procaine infiltration
Dose
Duration
Duration w/ Epi
What type of local is it
o*Procaine (Novocain)- max plain- 350-600 mg-
§ Duration- 45-60 min
§ Max with epinephrine- 1000 mg with duration 30-90 min
she’s an ester
Chloroprocaine other name
dose
duration
w/ epi
type
o *Chloroprocaine (nesacaine)- 1% max plain 800 mg
§ Duration- 30-60 min
§ Max with epinephrine- 1000 mg duration 30-90 min
its an ester
Tetracaine
Dose
Duration
Type
Pontocaine
Dose: MAx plain 100 mg
Duration
ESTER
How are amides metabolized
oxidative reaction in the liver
Lidocaine other name
Type
Dose
Duration
EPi dose and duration
Xylocaine
AMIDE
0.5-1* max plain 300 mg (4.5mg/kg)
Duration: 60-120 minutes
EPI (7mg/kg) 500mg max
Duration- 120-240 minutes
Mepivacaine other name
Type
Dose/Duration plain
Dose/Duration EPI
Carbocaine
Dose plain: 0.5-1% (7mg/kg) max 300mg
Duration 90-180 minutes
EPI 500mg (7mg/kg) with 120-240 min duration
Bupivacaine other name
Type
Dose/Duration Plain
Dose/Duration EPI
Marcaine
Dose Plaine 0.25% 2.5 mg/kg or 175 mg
Duration Plain - 240-480 min
Epi : 3mg/kg or max 225mg with 120-240 duration
What is Tumescent Anesthesia
Dose
· Tumescent solution- sodium chloride, lidocaine, epinephrine & bicarbonate injected into adipose tissue
· Maximum dose- 45 mg/kg
· Liposuction associated with a mortality rate of 19.1 per 100,000 procedures
o Leading cause of death- pulmonary embolism
What does adding Epi to a local do?
· Decreases the rate of local absorption secondary to vasoconstriction
· Allows for ability to administer more local
What are the doses of Epi for Injecting a local?
§ 1:50,000= 0.02 mg/ml or 20 mcq/ml
§ 1:100,000= 0.01 mg/ml or 10 mcq/ml
§ 1:200,000= 0.005 mg/ml or 5 mcq/ml
Concerns the NA should have when using Epi in a local
§ Tricyclic Antidepressants
Tofranil, Elavil
May lead to HTN
Reduce Epinephrine dose
§ Cocaine Interaction may lead to HTN & cardiac dysrhythmias
§ For a patient on tricyclic’s or using cocaine: Monitor BP & HR Q3 mins. after injection. May administer more Epinephrine if no change
§ Avoid Epinephrine concentration of 1:50,000
Spinal Effects- ORder of Block
§ Order of block
§ S– Sympathectomy = Drop in BP
§ T- Temperature
§ P- Pain
§ T- Touch
§ P- Pressure
§ M- Motor
§ V- Vibratory
§ P- Proprioception
Match the Effect to the Fiber
Sympathectomy
B fiber
Match the Effect to the Fiber
Temperature and Pain
C fibers and A fibers
Match the Effect to the Fiber
Touch
Delta Fiber
Match the Effect to the Fiber
Muscle tone
Gamma Fibers
Match the Effect to the Fiber
Pressure
Beta fibers
Match the Effect to the Fiber
Motor, VIbratory, Proprioception
Alpha Fibers
Epidural Effects compared to a Spinal
§ Block is more gradual
§ CNS block is gradual- less side effects
§ Spinal/Epidural can decrease intraoperative blood loss and embolic complications
Complications of Spinals
hypotension
High Spinal C3-5- bye bye breathing
Post dural Puncture HA (posterior, frontal or occipital
Tinnitus
Diplopia
How do you treat hypotension of a spinal
either prehydrate w/ IVF = 15 mL/KG
or cotreat as you go along
Ephedrine 5-10 mg IV
What complications do young females or pregnant ladies have
PDPH HA
Diploplia
Tinnitus
incidences increased with a larger needle
How to decrease incidence of HA for someone getting a spinal
use a smaller needle
turn the bevel to the side
para median appoach
Round/blunt tip needle
Hydration
How do you treat a PDPH?
Analgesics/NSAIDs
Bed rest
Hydration
Caffeine infusion 500 mg/1L over 1-2 hrs.
Sphenopalatine block- 1-2% lidocaine*
Epidural blood patch
o 10-20 ml auto blood via epidural injection- 90% effective
describe the sphenopalatine block and what it is for
· Sphenopalatine block (SPG)-
o Soak a 10 cm cotton-tipped applicator in 1-2% lidocaine or 0.5% bupivacaine
o Sniffing position, insert the applicator into the naris on the unilateral side of the headache
o Insert till resistance at the posterior wall of the nasopharynx
o Remain in place for 5-10 minutes
only treats the symptoms of a PDPH
List minor complications of a spinal
N/V
Mild Hypotension
Shivering (55%)
Itching (46%)
Urinary Retention
Transient mild hearing impairment
List 2 moderate complications of a spinal
failing the spinal…. sad
PDPH
Major Complications of a SPinal
IE Why im terrified of doing them
Direct needle trauma
Infection
Hematoma (1 in 220k)
Spinal cord ischemia
cauda equina syndrom- cutting them fibers by accident
Total spinal t1-t3 = bradycardic
T4 = hypotension
CV collapse and DEATH
complications of an epidural
hypotension
accidental spinal- can occur with injection or migration of the catheter
- stop injection- treat w/ fluid/ephedrine/ may need an airway
What is a common complication of epidural anesthesia?
Hypotension
Treated with hydration and ephedrine
What can cause accidental spinal complications?
Injection or migration of catheter
Treatment includes stopping injection, treating with fluid/ephedrine, and addressing possible airway issues
What is the incidence of death associated with spinal anesthesia?
1:150K
This indicates a rare but serious risk
What is a potential outcome of inadequate analgesia during epidural anesthesia?
Inadequate analgesia
This can lead to patient discomfort and dissatisfaction
What type of injection can lead to intravascular complications?
Intravascular injection
This is a significant risk during regional anesthesia
What is a rare complication associated with epidural procedures?
Epidural abscess
Incidence ranges from 1:6,500 to 1:500,000
What are transient neurological symptoms (TNS)?
Symptoms described in 1993
Indicates a complication that can occur after epidural anesthesia
What is Local Anesthetic Systemic Toxicity (LAST)?
Usually from an intravascular bolus
Most common cause is inadvertent intravascular injection during regional anesthesia
What are the signs and symptoms of LAST?
Tinnitus, lightheadedness, dizziness, slurred speech, confusion, circumoral numbness, metallic taste, bradycardia, hypotension, arrhythmias, seizures, coma, death
Symptoms vary based on plasma concentration of local anesthetic
What treatment is recommended for Local Anesthetic Systemic Toxicity?
Stop local anesthetic, provide oxygen, manage airway, treat BP/HR, arrhythmias
ACLS is the first step, followed by lipid emulsion treatment if needed
What is the recommended lipid emulsion dosage for LAST treatment?
1.5 ml/kg IV bolus over 1 min, followed by 0.25 ml/kg/min IV infusion
This is a critical component of LAST management
What medications should be avoided in LAST treatment?
Vasopressin, lidocaine, procainamide
These can reduce the effectiveness of lipid emulsion therapy
What is the effect of epinephrine in LAST treatment?
Doses <1 mcg/kg IV reduce lipid effectiveness
Caution is advised when using epinephrine
What alternative medication is suggested for arrhythmias during LAST?
Amiodarone
Preferred over other antiarrhythmics in this scenario
What is the most common side effect associated with neuroaxial opioids?
Pruritus
More common in obstetric patients and can be treated with naloxone.
What are the effects of hydrophilic drugs on respiratory depression?
Cause a biphasic respiratory depression
Hydrophilic drugs have a different impact on respiratory function compared to lipophilic drugs.
What happens with the use of lipophilic drugs in neuroaxial opioids?
Quickly absorbed by spinal tissue, which limits spread
This absorption affects the distribution and effects of the drug.
Which demographic is more commonly affected by urinary retention when using neuraxial opioids?
Young males
Urinary retention occurs due to the inhibition of sacral PSNS tone.
What physiological effect leads to urinary retention in patients using neuraxial opioids?
Inhibits sacral PSNS tone, leading to detrusor muscle relaxation and sphincter contraction
This mechanism results in difficulties with urination.
What is a treatment option for the side effects of urinary retention?
Naloxone
Naloxone can reverse the effects of opioids, alleviating urinary retention.
What causes nausea and vomiting in patients receiving neuroaxial opioids?
Activation of opioid receptors in area postrema of medulla & vestibular apparatus
This activation can lead to significant discomfort in patients.
What is a benefit of using an epidural over a spinal block?
Decreased incidence of headache
However, if the dura is punctured during the procedure, the risk of headache is very high.
When is a spinal block particularly advantageous?
Good for rapid onset
Spinal blocks provide a better and denser block compared to epidurals.
True or False: Epidurals are preferred when sudden changes in blood pressure are not wanted.
True
Epidurals can help maintain stability in blood pressure during procedures.
