Bier Block Flashcards
Advantages / Indications of Bier Block
6/3 things (BERM-RC / ETM)
- Bloodless field
- Ease of admin
- Rapid Onset
- Muscular Relaxation
- Rapid Recovery
- Control of Anesthesia
*Ease of procedure offset by potential systemic side effects
*Time is limiting factor for what procedures
*Mostly distal extremities and or superficial
BERM-RC / ETM
Contraindications of Bier Block
6 things (DIS-DIP)
- Do not use Bupivacaine or Ropivacaine
- Ischemic Limb
- Sickle-Cell
- Do not use Epi in anything
- Infection
- Patient refusal
Limitations of Bier Block
4 things (MNST)
- Must be inflated for at least 15-20 before deflating
- No analgesia once cuff is down
- Short duration: 45-60min
- Tourniquet Pain
Deflation of cuff before 15-20 mins
- Bounce cuff (deflate then rapid inflate)
- Eval pt for 5-10 mins (LAST symptoms)
- Deflate cuff again and continute to eval in OR for LAST
Topical LA
Skin
- Slow Onset
- Need EMLA (Eutectic Mixture of Local Anesthetic)
- Limited duration of action
Topical LA
Do not use on
- Mucous membrane
- Broken Skin
- Neonate (< Month old)
- If allergic
Mucous Membrane LA
Benzocaine
- Fast Onset
- Very Effective
- Much faster absorption
Systemic absorption of IV LA depends on blood flow
Site of injection fastest to slowest (I TIP-EBSS)
- IV or arterial
- Tracheal / Transmucosal
- Intercostal
- Paracervical
- Epidural / Caudial
- Brachial Plexus
- Sciatic
- Subcutaneous
I TIP-EBSS
What slows down absorption of LA
- Site of Injection
- Addatives (Epi)
- Higher lipid solubility
- Dosage and Volume
LA Distribution
- ⬆ perfused organs have quicker and ⬆ concentration levels
-more susceptible for toxicity - Lungs are the bulk of uptake and sequestration
Metabolized
Esters
Hydolyized by pseudocholinesterase
Rapid
Metabolized
Amides
Liver CYP450
Renal elimination
Ester LA’s
only one “i” in name
Metabolite PABA
* can cause anaphylaxis
Pseudocholinesterase deficiency at risk for toxicity
Cocaine is only oddball, hydrolized in liver
Amide LA’s
- Name has two “i’s”
- Prilocaine metabolizes into “o-toluidine” = methemoglobinemia
Rate of Amide hydrolysis
Short acting to long acting
Prilocaine>Lidocaine>Mepivicaine>Ropivicaine>Bupivicaine
LA Toxicity: Neurological
7 in order: CTDT-BIS
- Circumoral Numbness
- Tongue Paresthesia
- Dizziness
- Tinnitus
- Blurred Vision
- Impending Doom
- Seizures
In order of comminality
LA Toxicity: Respiratory
- Lido depresses hypoxic drive
- Relaxes smooth muscle = bronchodilaiton
LA Toxicity: Cardiovascular
4 things
- ⬇ contractability
- ⬇ conduction velocity (Chronotropy)
- Relaxes smooth muscle = vasodilation
- Higher doses=contractile depression, hypotension, and arrhythmias (possible cardiac arrest)
LA Toxicity: Immunological
- Anaphylaxis
* PABA
Methylparaben = preservative similar to PABA
LA Toxicity: Muscular
Mildly miotoxic
-4 week regen time
LA Toxicity: Hematological
- Lidocaine
Reduced Thrombosis, Increased Fibrinolysis (⬇ DVT) - Methemoglobinemia (Oxidized Fe2+ to Fe3+)
Prilocaine
Benzocaine
LA Toxicity: PaCO2 and pH
Respiratory depression causes ⬆ PaCO2 = ⬆ cerebral vasodilation (⬆ blood flow) = CNS toxcicity
pH decreases (acidodic) causes ⬆ in LA duration
Acidosis causes furhter cardiovascular collapse
LAST Symptoms
5 things: SHARL
- Seizure
- Respiratory distress
- Arrythmias
- Hypotension
- Lastly cardiac arrest
LAST Treatment
4 things: VICS
- Intralipid: 1.5-3.0 mL/kg
- Vent support
- Cardiac suport (Epi 10-100mcg)
- Seizure supression (Versed, Prop, Pentothal)
