ASA classification

American Society of Anesthesiologists (ASA) Classification

  • ASA I: Normal/healthy pt

  • ASA II: Pt with mild systemic dz

  • ASA III: Pt with severe systemic dz

  • ASA IV: Pt with severe systemic dz that is constant threat to life

  • ASA V: Moribund (at point of death) not expected to survive without surgery

  • ASA VI: Brain-dead donor pt

Types of Anesthesia

Anesthesia consists of Amnesia, Analgesia, Muscle paralysis

  • Local anesthesia

    • One-time injection of medicine that numbs a small area of the body

    • Used for procedures such as performing a skin biopsy or breast biopsy, repairing a broken bone or stitching a deep cut

    • You will be awake and alert, and you may feel some pressure, but you won’t feel pain in the area being treated

  • Monitored Anesthesia Care (MAC)

    • Conscious sedation or twilight sedation, typically is used for minor surgeries or shorter, less complex procedures when an injection of local anesthetic isn’t sufficient but deeper general anesthesia isn’t necessary

    • These procedures might include some types of biopsies or involve the use of a scope to examine the throat or colon to find and treat medical conditions such as cancer

    • An analgesic is often combined with sedation

  • General Anesthesia

    • IV medications or inhaled volatile anesthetics that render unconsciousness, amnesia, analgesia, loss of reflexes of the autonomic nervous system, and in some cases paralysis of skeletal muscles

  • Regional Anesthesia

    • Consists of neuraxial anesthesia via spinal or epidural injections and peripheral nerve blocks

    • The use of local anesthetics to block sensations of pain from a large area of the body, such as an arm or leg or the abdomen

    • Regional anesthesia allows a procedure to be done on a region of the body without your being unconscious. Used often in conjunction with general anesthesia to decrease narcotic requirements

Local anesthesia

% to concentration

Percent solutions are 1000mg/100ml:

  • 2% solution is 20mg/ml

  • 0.5% is 5mg/ml


  • 1:1,000 ➔ 0.1% ➔ 1 mg/ml

  • 1:10,000 ➔ 0.01% ➔ 0.01 mg/ml

  • Local anesthetics ⊣ Na channels:

    • ↓ nerve conduction ➔ ↓ pain - ↓ motor, touch/pressure (depending on duration of action and dose)

    • All local anesthetics can ➔ CNS & cardiac tox ➔ seizures & arrhythmias

  • Local infiltration anesthesia - Anesthetic directly into subcutaneous tissue

    • Primarily for minor surgical procedures like suturing, foreign body removal

      • Vasoconstrictors (epinephrine) ➔ vasoconstriction ➔ ↓ absorption ➔ ↑ duration of action

      • Aspirate before injection ➔ ↓ vascular infiltration

      • Acidic tissue (inflamed/infected) ➔ ↓ efficacy

  • Peripheral nerve block

    • Injected near a specific nerve or nerve bundle

    • Primarily for digital nerve block, extremities, scalp, neck, trunk surgery

  • Esters: Metabolized after absorption by serum esterase to PABA (source of allergy)

    • ↑ risk of allergic rxn. ↑ risk of systemic toxicity

  • Amides (have i in name before caine): Metabolized by hepatic CyP450

    • Pts with ester allergy are likely to tolerate an amide

  • TAKE HOME: If pt says I'm allergic to Procaine (an ester)... they might be ok with lidocaine ("i" in the name before "caine")

Malignant hyperthermia – fever and rapid incline in EtCO2

  • Always ask patient if there is any family history during pre op interview

  • SSX

    • Shocky ➔ confusion/weakness

    • Dramatic ↑ in body temperature (can be 13 degrees Fahrenheit) ➔ tachy, flushing, sweating

    • Rigid/painful muscles, especially in the jaw

    • ↑ RR

    • Brown urine

  • Triggered by:

    • Desflurane, Enflurane, Ether, Halothane, Isoflurane, Methoxyflurane, Sevoflurane

    • Succinylcholine

  • TX

    • 2.5 mg/kg dantrolene IV push immediately

      • Another 1-2.5mg if hyperthermia persists (maximum cumulative dose 10 mg/kg)

      • 1 mg/kg IV dantrolene q 6hrs for 24hrs

Local Anesthetic Toxicity

  • Unintended intravascular injection ➔ systemic absorption of LA

  • SSX - CAN OCCUR > 15min after injection

    • CNS: Tinnitus, Circumoral numbness/Metallic taste, Agitation, Dysarthria/Seizures, Loss of consciousness/Respiratory arrest

    • Cardiovascular: Hypotension, Bradycardia, Ventricular arrhythmias

  • TX

    • 20% lipid emulsion

    • Maximum dose lipid emulsion approximately 12 mL/kg IV

    • Suppress seizures (benzos preferred)

    • Follow ACLS - EXCEPT: Less epi boluses; amiodarone is first line antiarrhythmic

      • Avoid vasopressin, calcium channel blockers, β blockers

    • Cardiopulmonary bypass if refractory to lipid emulsion and ACLS

General Anesthetics

IMPORTANT (wise words from a CRNA)

  • Pre-sedation with fentanyl/midazolam while applying monitors and positioning patient

  • Pt is pre-oxygenated followed by induction of general anesthesia

  • Renders unconsciousness with propofol/etomidate and a paralytic agent (rocuronium or succinylcholine) followed by intubation

  • Maintenance of general anesthesia with IV or inhaled anesthetics

  • Emergence from anesthesia consists of reversal of any paralytic agents, narcotic titration as needed, discontinuation of anesthetic agents

  • Followed by extubation and return of consciousness

  • During this process patients will progress through various stages of anesthesia depths, see below... 1,2,3,2,1 respectively

    • Stage 1 - Analgesia

      • conscious but drowsy

      • painful stimuli response is reduced

    • Stage 2 - Excitement

      • lose consciousness

      • no response/reflex to painful stimuli

    • Stage 3 - Surgical anesthesia

      • movement ceases and respiration becomes regular

    • Stage 4 - Medullary paralysis

      • respiration and vasomotor control cease

      • death occurs

Most dangerous aspects are induction and emergence of anesthesia while patient is in Stage II

  • Big risk of Laryngospam with any stimulation

  • OR should be quiet and staff should be readily available to assist anesthesia should complications arise

Parenteral Anesthetics

Induction - Short acting (5-10min) - Potentiate GABA

    • Thiopental (Pentothal) - Lipophilic ➔ hangover

    • Methohexital (Brevital) - Lipophilic ➔ hangover

    • Propofol (Diprivan) - rapidly metabolized; Fospropofol - prodrug (Lusedra)

    • Etomidate (Amidate) - RAPID induction/conscious sedation - low cardiovascular risk - less likely to ↓ BP


    • Fentanyl (Sublimaze) - Opioid IV (or epidurally in combo with other drugs) for surgery/obstetric analgesia/anesthesia

      • Good during cardiac surgery because it does not cause cardiac toxicity

      • But, fentanyl does not ➔ amnesia so often combined with benzo like midazolam to ➔ amnesia and ↑ sedation

    • Midazolam (Versed) - Slower onset but short acting benzo, good for pre-op/endoscopy sedation

      • Less cardiac/respiratory depression

      • Reverse OD with flumazenil

    • Ketamine (Ketalar) - IV admin ➔ dissociative anesthesia - dissociated but no complete loss of consciousness

      • Analgesia, reduced sensory perception, immobility, amnesia

      • ↑ blood pressure, but little effect on respiration with typical doses

      • During recovery: can have delirium, hallucinations, irrational behavior (less likely in kids)

      • Combo with benzo for anesthesia during minor surgery/diagnostic procedures


    • Succinylcholine - Depolarizing Neuromuscular Blocker (persistent depolarization of motor end plate)

      • When first pushed ➔ transient muscle contractions (fasciculations) quickly followed by sustained muscle paralysis

      • Short duration of action (5-10min) - good if you can’t get the tube

      • For non emergent pt: screen for family hx of atypical cholinesterase, obtain serum K level (can cause hyperK)

        • Avoid in kids, third-degree burn pts, unhealed skeletal muscle injury (↑ risk of hyperK) and ↑ ICP/eye injury

        • Can cause malignant hyperthermia

    • Rocuronium - Non-depolarizing - Neuromuscular Blocker (competitive antagonists of ACh at nicotinic receptors)

      • Aminoglycoside/tetracycline abx & CCB can potentiate

      • Longer duration of action (30-60min)

        • Can be reversed with cholinesterase inhibitor - neostigmine

Rapid Sequence Intubation

    • Rapid admin of induction agent immediately followed by paralytic

      • Preoxygenate, Etomidate, Sux, Tube, Confirm placement listen/EtCO2/color change