Peripheral Nerve Block Techniques Flashcards
What type of hormones are increased during a stress response?
Catabolic (cortisol and catechols)
What types of hormones are decreased during a stress response?
Anabolic (human growth hormone and testosterone)
How is glucose increased during a surgical stress response?
Increase in conversion of amino acids to glucose through liver gluconeogenesis
What form of anesthesia can blunt the surgical stress responses and increased metabolic demand?
Regional anesthesia
Define regional anesthesia.
Loss of sensation in a region of the body produced by application of an anesthetic agent to all the nerves supplying that region
What is a significant difference between regional anesthesia and general anesthesia?
There is no loss of consciousness with regional anesthesia
What is conduction anesthesia?
Anesthesia of an area supplied by a specific nerve, produced by an anesthetic agent applied to the nerve
What are absolute contraindications for regional anesthesia?
Patient refusal
Infection at injection site
Coagulopathy
What are relative contraindication for regional anesthesia?
Hypovolemia
Systemic sepsis
Preexisting neurological conditions
If the patient has received regional anesthesia what does that indicate regarding the characteristics of the block?
Implies loss of all sensations –> autonomic, motor, and sensory
If the patient has received regional analgesia what does that indicate regarding the characteristics of the block
Loss of pain sensations –> only sensory and autonomic
What are the goals of local anesthetic?
Rapid Onset
Appropriate duration
Lowest toxicity
Adequate analgesia/anesthesia
What type of tool can aid the provider in using less LA?
Ultrasound
What type of regional anesthesia is the exception to volume equalling success?
Spinal, use a very small amount compared to other blocks
What are the three components that must be balanced when administering regional anesthesia?
Volume
Concentration
Toxicity
If a local anesthetic has a faster onset, what can be assumed about the duration?
Shorter duration
What order do nerve fibers become blocked?
B C & A-delta A-gamma A-beta A-Alpha
What is the function of A-Alpha nerve fibers?
Motor and proprioception
What is the function of A-beta nerve fibers?
Motor, proprioception, touch and pressure
What is the function of A-gamma nerve fibers?
Muscle tone
What is the function of A-delta nerve fibers?
Pain, touch and cold
What is the function of B nerve fibers?
Preganglionic sympathetic
What is the function of C nerve fibers?
Pain, touch, warm and cold
What drugs should be readily available prior to performing regional anesthesia?
Supplemental O2
Narcotics/sedatives
Resuscitation drugs –> LAST
What is a paresthesia?
Occurs with direct contact of needle to nerve “electric shock”
What is the purpose of the nerve stimulator when placing a regional anesthetic?
Isolated specific nerves using adjustable, low voltage stimulator
What is the highest amplitude a nerve stimulator should go if using for purpose of regional anesthesia?
No more than 5mAmps (0.1-5mA)
How will the provider know that an accurate localization of the nerve is present?
The lower the threshold current the more accurately the nerve is located
What should the provider use a nerve stimulator with an insulated needle when performing regional anesthesia?
Reduces current leakage
Ideally, what would the provider like the amplitude to be when locating a nerve?
Greater than 0.2mAmp tom make sure we aren’t in the nerve itself
What is a major complication of regional anesthesia?
LAST
In what order are the areas most likely to experience LAST?
Tracheal –> Intercostal –> Caudal –> Epidural –> lumbar –> brachial plexus –> Sciatic –> femoral –> Subcutaneous
What should the provider do prior to injecting the LA?
ALWAYS aspirate before each injection
How much LA should the provider inject prior to aspirating again?
Incremental doses of 5mL or less
What might the patient tell the provider if there is a intramural injection?
Patient will be screaming in pain
What can occur if LA is injected intraneurally?
Damage to the nerve can occur
If the patient tells the provider they are feeling dull achy pain and cramps what might this indicate?
Pressure from volume being injected around the nerve, temperature is cold compared to body temperature
What are the symptoms in the progression of LAST?
Disorientation Metallic taste Tingling in the mouth and tongue Tinnitus and auditory hallucinations Muscle spasms Seizure Coma Respiratory arrest Cardiac Arrest Death
How should LAST be treated?
Airway –> secure airway
Breathing –> ventilation prevent acidosis
Circulation –> CV support
Drugs –> drugs to increase seizure threshold
