2 - Anesthesia Flashcards
Normal pH of local anesthetics:
5.5 - 6.0
Do not work well in infected tissue (more acidic environment)
Can add bicarb to buffer
How do most local anesthetics work?
Block Na channels and impair propagation of action potentials
Thinner nerve fibers and myelinated fibers are more easily blocked
Advantages of epi in locals
Vasoconstrictor
Increased duration of action
Decreased bleeding
Decreased volume needed for anesthesia
Disadvantages of epi in locals
Increased myocardial activity
Tachycardia
HTN
Dysrhythmias
Avoid in pts with known cardiac dz, HTN, DM, thyroid problems
Describe the ideal anesthetic
Short latency Superior penetration Non-addictive Completely reversible Low toxicity Stable and water soluble Non-irritating Inexpensive
MC adverse effects of local anesthetic
Urticaria
Erythema
Edema
Dermatitis
Txt - O2, Epinephrine, fluids, antihistamine, steroids
Toxicity from locals - prodromal sxs
Cicrumoral numbness / mouth tingling
Tinnitus
Lightheaded / dizzy
Metallic taste in mouth
Toxicity from locals - CV problems
HTN then HOTN
Tachy or brady
CV collapse
Toxicity from locals - severe CNS:
Tonic-clonic activity
ALOC -> unconsciousness
What do you do prior to injecting to avoid intravascular injection?
Aspirate first
Bupivicaine not recommended for:
Kids under 12yrs
Lidocaine dosing
Maximum dose 4mg/Kg WITHOUT epinephrine up to 300mg
Maximum dose 7mg/Kg WITH epinephrine up to 300mg
1% lidocaine has 10mg/ml •
2% lidocaine has 20mg/ml •
Onset 2-5 minutes •
Duration 0.5-2 hours
Management of toxicity
CNS sxs? Hyperventilate
CV sxs? IV fluids for HOTN, txt the arrhythmia
Malignant hyperthermia - MC to succ - txt with rapid cooling, bicarb, dantroline
Method for injecting local
Large coverage with one puncture (longer, small gauge needle
Bent 45 degrees, hub the needle, inject as you withdraw
Sequence of clinical anesthesia
Vasodilation - loss of sympathetic tone
Loss of pain/temp sensation
Loss of pressure sensation
Loss of motor function
Peripheral nerve blocks - common sites?
Plantar aspect of foot
Palmar aspect of hand
Aseptic technique
Max dose Bupivicaine?
2mg/kg up to 100mg
Describe spinal (subarachnoid) block
Lower abdominal
Lower extremity
GU
GYN
Small volume of concentrated solution (anesthetic, narcotic, with or without epi)
Blocks sympathetic, sensory, motor function
How to prevent toxicity?
Combine small amounts of different agents
Better than maxing out one thing
Where is epidural anesthesia injected?
Into the epidural space, NOT the CSF
Describe epidurals
Catheter taped to the skin
Requires continuous infusion of larger amounts of anesthetic
Blocks sensory but not necessarily motor function
Good for rib fx’s
Acute complications of nerve blocks
HOTN (neurogenic shock)
- txt with fluids and pressors
High spinal - bradycardia, HOTN, arm tingling, respiratory distress (must ventilate)(diaphragm innervated by C3-C5)
Cauda equina - bladder and bowel dysfunction, motor and sensory changes in legs
Later complications of central nerve blocks
MC - urinary retention
Monitor post-op UOP
May need catheterization (a foley is fine, they don’t need a suprapubic catheter)
Spinal HA 2/2 CSF leaking out of the dura - ICP decreases with postural changes - txt with IV fluids, caffeine, blood patch (autotransfuse blood into epidural space)
Epidural hematoma - compresses spinal cord - suspect if pt is anticoagulated - anesthesia will likely be avoided in these patients
Dermatomes - Clavicles, nipples, umbilicus
Clavicles - C5
Nipples - T4
Umbilicus - T10
Conscious sedation provides
Analgesia and anxiolysis
Minimally depressed level of consciousness
Usual combo for conscious sedation?
Benzo and narcotic
OR
Propofol and narcotic
Intubation in conscious sedation?
Nope - patient maintains their own airway
Nice perks of conscious sedation?
Still follows commands
Doesn’t remember any of it later
Examples of procedures in which conscious sedation is used
Bronchoscopy EGD/colonoscopy Thoracostomy Closed reduction of fx’s Procedures in kids
What does propofol provide (and not provide)?
It’s a sedative-hypnotic
So… anxiolysis, muscle relaxant, anticonvulsant
BUT
NO DIRECT ANALGESIC EFFECT
Patient safety during conscious sedation
Have a crash cart there
Follow your SOP’s
NPO beforehand
ASA class I and II patients
Pt has a dedicated staff member (nurse) to monitor vitals, etc
Crash cart:
O2 Airway adjuncts ACLS drugs Defibrillator Suction Narcan Flumazenil
PACU
Home once goals are met:
- stable out of bed for 30mins
- stable vitals
- fully responsive
- ambulatory
- oriented
- pain / nausea controlled
- voiding
Goals of general anesthesia
Pain control
Amnesia
Muscle relaxation
General anesthesia - airway mangement
Intubate or supraglottic
Laryngoscope or Glidescope
Fluids and blood products during general anesthesia
Central vs peripheral lines Continuous vitals IV fluids and UOP Protect eyes and pressure points Prevent hypothermia
Complications of general anesthesia
Hypoxemia
Aspiration (NPO pre-surgery, may use antacids, Sellick during intubation)
Nerve injury (pad the pressure points, do not hyperextend joints, lubricate and tape eyes closed
How do you feel about a local anesthetic?
Actually, I’d prefer an imported one.
