Blocks/ Epidurals/ Pain Management Flashcards
What are opioids/ narcotics?
Bind to Mu, Delta, Kappa receptor sites to produce morphine like or opioid agonist effect by acting on pain modulating system. Can be natural or synthetic. Caution: watch out for respiratory depression.
What is morphine?
Prototype for strength of other narcotics
Can cause histamine release
Can cause spasm of biliary smooth muscle
Useful in treatment of angina in ACS
Peak effect in 20 minutes
Morphine facts
Route IV
Dose 2-15mg
Onset < 1 minute
Peak 20 minutes
Duration 2-7 hours
What is hydromorphone?
6x more potent than morphine
Recommended in renal patients d/t lack of active metabolites
Hydromorphone facts
Dose 0.5 - 2mg IV
Onset < 60 sec
Peak 5 - 20 min
Duration 2 - 4 hrs
What is fentanyl?
100x more potent than morphine
Can cause fixed chest syndrome
Fentanyl facts
Dose 0.05 - 2mcg/kg IV
Onset < 30 sec
Peak 3 - 7 min
Duration 30 - 60 min
What is fixed chest syndrome?
Can be caused by rapid IV injection of Fentanyl
Leads to bronchial constriction and resistance to ventilation, rigidity of diaphragmatic and intercostal muscles.
Reversal - administer subclinical dose of succinylcholine (w/c will relieve rigidity of chest wall?)
Additional action - Ventilate
What is Meperidine?
1/10x as potent as morphine
Primary for post operative shivering
Not commonly used for pain
Contraindications
a. Use of MAOIs - d/t resp depression w/ concurrent use of meperidine
b. potentiates seizure
What are commonly prescribed MAOIs?
Selegiline
Isocarboxazid
Phenelzine
Tranylcypromine
Meperidine facts
Dose 12.5 - 25 mg
Onset 1 - 3 min
Peak 5 - 20 min
Duration 2 - 4 hrs
What is opioid overdose treatment?
Naloxone
0.2 - 0.4mg reverses respiratory depression
Titrate 0.04mg to avoid acute reversal of analgesia
What are advantages of local anesthesia?
Postop analgesia on site
Safe for patients with systemic disease
Fewer side effects (PONV, sedation, respiratory depression)
What are the disadvantages of local anesthesia?
Toxicity
Allergic reaction
IV injection
Inadvertent infiltration
What are types of local anesthetics?
Esters (one “i”)
1. Cocaine
2. Procaine
3. Chloroprocaine
4. Tetracaine
What are types of local anesthetics?
Amides (two “ii”)
1. Prilocaine
2. Lidocaine
3. Mepivacaine
4. Bupivacaine
5. Etidocaine
6. Ropivacaine
What to watch out for in administering Prilocaine (Amide - local anesthetic)?
! Can cause methemoglobinemia - abnormal amount of methemoglobin in the blood leading to hypoxia
d/t prilocaine toxic build up
! s/s tachypnea, brown-grey cyanosis, metabolic acidosis, chocolate colored blood
tx with methylene blue
What to watch out for in administering Bupivacaine (Amide - local anesthetic)?
! Do not use for bier block
! Can cause cardiac toxicity if excessive dose or accidental injection
Blocks sensory more than motor function
What to watch out for in administering Mepivacaine (Amide - local anesthetic)?
! Do not use for spinal anesthesia
! Great alternative to lidocaine with epinephrine without vasodilation effect
How are local anesthetics metabolized?
Esters - hydrolyzed by plasma cholinesterase (aka acetylcholinesterase, produced by liver and ALSO BREAKS DOWN SUCCINYLCHOLINE)
Amides - metabolized by liver
What are important properties of local anesthetics?
Onset
1. Amides with more rapid onset
2. Site infection and acidosis slows onset
3. Increased risk of toxicity with hypoxia and acidosis
4. Adding bicarbonate speed onset and decreases duration of effect
What are important properties of local anesthetics?
- Adding vasoconstrictors (epinephrine) slows absorption of local anesthetics
- Adding vasoconstrictor decrease bleeding
- Absorption is dose related
- Highly vascular areas with faster systemic absorption
What is local anesthesia CNS toxicity?
Can occur d/t accidental injection into blood vessel or overdose
What are the signs and symptoms of local anesthesia CNS toxicity ?
!Circumoral numbness
!Lightheadedness
!Tinnitus
!Metallic taste in mouth
!Slurred speech
!Muscle twitching
!Can progress to grand mal seizures and coma
What is the treatment for local anesthesia CNS toxicity ?
!Apply oxygen at first signs.
May administer versed, valium, or thiopental for seizure activity
What are other treatments for local anesthesia CNS toxicity?
- Early detection
- Support circulation with fluids, vasopressors, antiarrhythmics
- Oxygen, airway management
- Control seizure activity
What are other treatments for local anesthesia CNS toxicity?
- CPR/ ACLS if necessary
- ! Lipid infusion
20% lipid emulsion for reversal of toxicity
IV Push - 1.5mL/kg over 1 minute
Infusion - 0.25mL/kg/min
Max dose 12mL/kg
What is local anesthesia cardiovascular toxicity?
!most common with Bupivacaine
d/t blocking of sodium channels in the heart
s/s includes hypertension leading to hypotension, PVCs, prolonged PR interval, CV collapse
What are the types of regional anesthesia
Topical anesthesia
Field block/ local infiltration
IV injection
Peripheral nerve block
Sympathetic nerve blocks
Neuraxial blocks (spinal, epidural)
What are topical and local infiltration for regional anesthesia?
Topical - Applied directly to Skin, Mucus Membranes, Urethra, Nose, Pharynx
Local Infiltration - Direct tissue injection, Blocks transmission of sensory impulses, Epinephrine can be injected into confined spaces
What is Bier Block (IV injection)?
Never use Bupivacaine for Bier Block ! d/t can cause cardiovascular collapse
Tourniquet applied to occlude circulation of arm or leg
Large doses of local anesthetic injected and stays in area d/t tourniquet
Risk of toxicity when tourniquet released d/t anesthetic can travel to systemic circulation
Common application: ganglion cyst removal, carpal tunnel release, tendon release
Patient receives Bier block for surgical procedure> What are potential complications?
cardiovascular depression
permanent occlusion of artery
pneumothorax
Horner’s syndrome
cardiovascular depression
What is peripheral nerve block?
Anesthetic injected to specific site to block conduction of nerve impulses
What are common types of peripheral nerve block?
- Cervical plexus – common for carotid endarterectomy
- Brachial plexus – 4 approaches
Interscalene for shoulder surgery
Supraclavicular
Axillary
Infraclavicular
Intercostal - Intercoastal block
What is cervical plexus block?
Used to block areas around neck
Commonly used for carotid endarterectomy, superficial neck procedures
What are complications of cervical plexus block?
Complications:
Injury to vertebral artery
Paralysis of diaphragm d/t phrenic nerve
block
Hoarseness for laryngeal nerve block
Inadvertent subarachnoid or epidural block
What is brachial plexus blocks: Interscalene/ supraclavicular?
Blocks arm from shoulder down (usually upper extremity surgery)
What are the different approaches of brachial plexus block?
Interscalene
Supraventricular
Axillary
Infraclavicular
What are the complications of Interscalene/ supraclavicular block?
!Horner syndrome (ptosis, miosis, nasal
congestion, vasodilation, increased skin
temperature)
Unilateral phrenic + laryngeal nerve block
Vertebral artery injection
Possible high spinal or epidural
Pneumothorax (check breath sounds)
What is axillary block?
Most popular, easy and safe
Commonly used for forearm, wrist and hand procedures
What are complications of axillary block?
IV injection
Hematoma if axillary artery is punctured
Contraindicated if patient with infected glands or the arm can not be abducted to 90 degrees at the shoulder
What is intercoastal block?
Useful for post op pain s/p thoracic or abdominal surgery, chest tube insertion
Also for rib fractures and neurolytic block for cancer
What are complications of intercoastal block?
Pneumothorax
IV injection
!Toxicity d/t rapid uptake by intercoastal
What is transverse abdominal plane block?
Local anesthetic injected to plane between internal oblique and transversus abdominis muscles
Interrupts innervation to abdominal skin, muscles, parietal peritoneum
What are common use for abdominal plane block?
bowel resections, ventral hernia repair, cholecystectomy, kidney transplant, total abdominal hysterectomy, C-sections
What is lower extremity block?
Indicated for procedures at or below knee
Lumbar plexus (psoas compartment block)
Femoral nerve block
Popliteal sciatic nerve block
Saphenous nerve block
Ankle block
What are complications of lower extremity blocks?
IV injection
Inadvertent arterial puncture
Neural trauma
What are the types of neuraxial blocks?
Spinal anesthesia
Epidural anesthesia
What are other miscellaneous blocks?
Paravertebral block (mastectomy)
Retrobulbar/ Peribulbar block (intraocular lens implant, posterior chamber/ retinal surgery, corneal implant, cataract surgery)
Airway block (difficult intubation, upper airway trauma, cervical spine fracture or radiculopathy, airway malignancy or abscess)
What is spinal anesthesia (intrathecal or subarachnoid block)?
Anesthesia on subarachnoid space
Anesthetize nerve root + part of spinal cord
Spinal - blocks nerve conduction in the region of body
Toxicity is rare d/t small doses given
!Baracity (heaviness of solution)
5-10% glucose added to anesthetic solution
makes medication heavier than CSF
Helps sink solution in CSF, thus affected by gravity +
patient’s position
What is subarachnoid space?
Web like
Contains CSF, arteries, veins
What is epidural anesthesia?
Injected into epidural space
Can be single, bolus, or continuous infusion (PCEA)
Higher chance of systemic toxicity d/t large dose req
More absorption to systemic circulation
Higher incidence of post Dural puncture headache
What is epidural space?
Potential space only
Must be created when accessed for injection of anesthetic
What is site or mechanism of action for spinal vs. epidural?
!Spinal - Nerve roots blocked as they pass through CSF
!Epidural - Nerve roots blocked outside CSF
What is the administration site for spinal vs. epidural?
!Spinal - Lower lumbar below termination of spinal
!Epidural - Lumbar or thoracic region
What is the dose of anesthetic for spinal vs. epidural?
!Spinal - small
!Epidural - large
What is the instrument for administration for spinal vs. epidural?
!Spinal - needle
!Epidural - needle or catheter
What is the ability to repeat for spinal vs. epidural?
!Spinal - no
!Epidural - yes
What is the onset of action for spinal vs. epidural?
!Spinal - rapid, intense blockade, may lead to hypotension
!Epidural - gradual, may have less intense blockade, BP decline is usually slower
Patient develops N/V s/p spinal anesthesia. Perianesthesia knows most concerning symptom requiring intervention:
hypothermia
spinal headache
hypotension
bladder distension
hypotension
What are significant considerations for neuraxial anesthesia (spinal/ epidural)?
Assess dermatomes to evaluate evolution, extent of anesthesia
Progress of block affected by many factors like
Dose + volume administered
Patient’s position s/p administration
Obesity, hormonal influence, pregnancy
What to watch out for in neuraxial anesthesia (spinal/ epidural)?
!Loss of temperature sensation first sign of sensory block
Feet affected first, then moves upward body
What are the indications for epidural anesthesia?
Surgical procedure involving lower extremity, perineum, abdomen
Treatment of acute and chronic pain
Obstetric procedure and labor analgesia
What are relative contraindications to epidural anesthesia?
Preexisting neural disease
Musculoskeletal abnormalities
History of back surgery
Untreated hypertension
What are absolute contraindications of epidural anesthesia?
Patient refusal
CVD - severe AO, mitral stenosis, asymmetrical septal hypertrophy
Severe uncorrected hypovolemia
Allergy to anesthetic agent
Increased ICP
Infection at injection site
Sepsis or bacteremia
Coagulopathy
What are precautions for epidural anesthesia?
Patients on anticoagulant can experience catastrophic complications
What are the dermatomes?
Each dermatome correspond to specific nerve root
Neck - C3
Clavicles - C5
Nipples - T4
Xiphoid - T6
Navel - T10
Groin - L1
Knee - L4
Dorsum of foot - L5
Lateral ankles - S1
What is the order for Loss/ Return of function during neuraxial anesthesia (spinal/ epidural)?
Autonomic + Sympathetic Function > sense of temperature > pain > touch > movement > proprioception (sense that lets us perceive the location and movements of our body parts - https://www.sciencedirect.com/topics/neuroscience/proprioception)
!Return of function is in the order of reversal of loss
Which of the following describes the recovery sequence from spinal anesthesia as indicated by dematome level?
Lower extremities, abdomen, chest, perineum
Chest, abdomen, perineum, lower extremities
Chest, abdomen, lower extremities, perineum
Lower extremities, perineum, abdomen, chest
Chest, abdomen, lower extremities, perineum
When is safe to discharge patient after neuraxial anesthesia (spinal/ epidural)?
!Inpatient - T10 level (navel) indicates that the spinal/ epidural is resolving
!Outpatient - S3 level ( ) indicates fully resolved
per facility policy
consider ability to void
What to watch out for in neuraxial anesthesia (spinal/ epidural)?
!Blocks higher than T6 but less than T3
HYPOTENSION more likely
Sympathetic output from the spinal cord is blocked
HR may increase in response
What to watch out for in neuraxial anesthesia (spinal/ epidural)?
!Blocks higher than T3
BRADYCARDIA more likely
Function of SA node can be affected (vagus nerve is unrestrained)
Patient received spinal anesthesia. BP=70/40, HR=38, RR=14, SPO2=96%. No sensation below T3 dermatome level. RN needs to anticipate which priority intervention?
immediate reintubation
atropine administration
monitoring cardiopulmonary arrest
starting dopamine infusion
starting dopamine infusion
What to watch out for in neuraxial anesthesia (spinal/ epidural)?
!Blocks higher than T1
Cardiopulmonary collapse
What is the treatment for hypotension d/t neuraxial anesthesia (spinal/ epidural)?
Elevate patient’s legs (but can worsen block). AVOID elevating head/ HOB. AVOID trendelenburg d/t increased risk of respiratory compromise, upward spread of anesthesia.
IV fluid bolus
Vasopressors for BP support (i.e. phenylephrine)
IV atropine if pronounced bradycardia
!High sensory block can lead to neurogenic shock
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Postdural puncture headache d/t CSF leak in dura mater:
More common in spinal anesthesia
More likely if large needle/ hole used
More likely occurs in younger people
More likely if sharp needles than blunt needles
What are the signs/ symptoms of postdural puncture headache?
Symptoms appear 24-48 hours after dura puncture:
HA worsened by sitting/ standing
Nuchal rigidity
Neck ache
Nausea
Visual and auditory disturbances
What are the treatments for postdural puncture headache?
Hydration
Caffeine
Blood patch
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Adhesive arachnoiditis:
chronic inflammation of arachnoid
progressive weakness/ sensory loss on lower limbs
leads to paraplegia
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Cauda equine syndrome:
leg numbness, bowel/ bladder dysfunction
usually permanent effects
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Septic meningitis (symptoms appear within 24 hours of injection):
fever, ha, neck rigidity, + Kernig’s sign (chin can’t touch chest)
good outcome with early antibiotic treatment
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Complete loss of chest wall sensation and c/o increasing difficulty breathing (suspect phrenic nerve paralysis - needs emergent intubation)
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Epidural hematoma - for patients with coagulopathies
S/S include sudden lower back pain, motor and sensory changes, bowel and bladder deficits
Treatment - emergent MRI/ CT/ spinal decompression
What are potential complications of neuraxial anesthesia (spinal/ epidural)?
Nausea and vomiting caused by hypotension
What are contraindications to neuraxial anesthesia (spinal/ epidural)?
Patient refusal
Coagulation deficiency
Infection at block site
