Anesthesia

Question 1

Inhaled induction agents

Answer 1

Cause respiratory depression, most have myocardial depression, increased cerebral flow, and decreased renal blood flow

Question 2

MAC

Answer 2

minimum alveolar concentration. Smallest concentration that causes 50% of people to not move with incision.
Smaller MAC = more lipid soluble-> more potent less water soluble slower the speed
Speed of induction inversely proportional to solubility. NO is fastest but, has low lipid solubility, has high MAC, low potency

Question 3

Sevoflurane

Answer 3

MC used. Fast, less laryngospasm. Less pungent. Good for mask induction

Question 4

Desflurane

Answer 4

Most rapid onset/offset. Pungent, not used for induction, reserved for maintenance

Question 5

Nitrous oxide NO2

Answer 5

minimal myocardial depression. Always used with sevoflurane or desflurane. Do not use with SBO or PTX
- Causes tremors

Question 6

Halothane

Answer 6

highest degree of cardiac depression and arrhythmias. Least pungent→ Good for kids

Question 7

Volatile anesthetic hepatitis

Answer 7

fever, eosinophilia, jaundice, Increase LFT

Question 8

Isoflurane

Answer 8

Good for neurosurgery, (lowers brain o2 consumption, no increase in ICP). Pungent, not used for induction

Question 9

Enflurane

Answer 9

can cause seizures

Question 10

MCC of intra-op bradycardia

Answer 10

inhaled anesthetic. Tx: atropine

Question 11

Inhalation induction agents

Answer 11

Nitrous oxide, halothane, sevoflurane, isoflurane, enflurane

Question 12

Intravenous induction agents

Answer 12

Propofol, ketamine, etomidate

Question 13

Propofol

Answer 13

-Not an analgesic
-Metabolized in liver
-Provides bronchodilation  #1 choice to patients with asthma or airway disease
- Best one to prevent post op nausea and vomiting
- Side effects: respiratory depression, hypotension
- Propofol infusion syndrome – causes bradycardia (must have this for dx), and METABOLIC ACIDOSIS, with hyperkalemia, renal failure, rhabdomyolysis, hepatomegaly, CHF. increased risk in kids
- Can measure CPK and lactate levels daily to catch early
- Treatment: stop propofol and start hemodialysis
- Propofol contraindicated in egg allergy, pregnant, Parkinson’s

Question 14

Dexmedetomidine (Precedex)

Answer 14

alpha 2 receptor agonist. Does not cause respiratory depression. Can decrease BP
-Anesthesia and analgesia
-sedation agent for intubated patients; not an induction agent
-Not recommended for more than 24 hours

Question 15

Ketamine

Answer 15

-Amnesia, analgesia
-No respiratory depression, good for children, safe with head injury
– Ischemic heart disease: can cause HTN and tachycardia leading to increased myocardial oxygen consumption

-Historically contraindicated in patients with elevated ICP and intraocular P; however no longer absolute contraindications

-

Question 16

Etomidate

Answer 16

Fewest cardiac side effects
Not an analgesic

SE: adrenal insufficiency/ supression, myoclonus, stevens-johnson syndrome, trismus

…post op fever, hypotension, hypokalemia

Question 17

Rapid sequence intubation

Answer 17

Pre-oxygenate, etomidate, succinylcholine, cricoid pressure

Question 18

1st/last muscles to go down/recover

Answer 18

Diaphragm: last muscle to go down, 1st muscle to recover from paralytics

Neck & face muscles: 1st to go down, last to recover

Question 19

Succinylcholine

Answer 19

*Only depolarizing agent & only one that causes fasciculations
-Metabolized by plasma pseudocholinesterase.
Atypical pseudocholinesterase causes prolonged paralysis with succinylcholine (Asians). Not reversible. Have to wait till it wears off.
-Open-angle glaucoma can become closed-angle glaucoma
Contraindicated in:
- neurologic diseases (spinal cord injury, neuromuscular disorders) Have upregulation of Ach receptors: hyperkalemia
- In head injury: increases ICP
-Severe burns, acute renal failure

Malignant hyperthermia

Question 20

Malignant hyperthermia

Answer 20

Defect in calcium metabolism
Calcium released from sarcoplasmic reticulum causes muscle excitation- contraction syndrome (ryanodine receptor defect)
SE: 1st= increase end-tidal CO2, then fever, tachycardia, rigidity, acidosis, hyperkalemia, rhabdomyolysis

Tx= dantrolene (10 mg/kg) inhibits Ca release and decouples excitation complex; cooling blankets, HCO3, glucose

Question 21

Non-depolarizing agents

Answer 21

inhibit neuromuscular junction by competing with acetylcholine

Cis-atracurium, rocuronium, vecuronium, pancuronium

Cisatracurium (Nimbex) – Hoffman elimination. Use this if patient has liver or kidney disease!!!!
Pancuronium – metabolized in kidney. Slow and long acting. MC SE is tachycardia. DON’T USE IN ANY ARRYTHMIA or CAD.
Rocuronium – 1 mg/kg for induction. Fastest acting. metabolized in liver. Little effect on blood pressure. Short half life
Vecuronium – Metabolized in kidney. Short half life

Reversal of non-depolarizing agent – Sugammadex is best. Also can use Neostigmine or edrophonium to block Ach-esterases. Add atropine or glycopyrrolate to counteract Ach overdose

Question 22

Local anesthetics

Answer 22

Amides - have 2 I’s. Lidocaine, bupivacaine, mepivacaine. Rarely cause allergic reaction
Esters - tetracaine, procaine, cocaine. Has higher risk of allergic reactions due to PABA

Benzocaine: can cause methemoglobinemia

Question 23

Narcotics (opioids)

Answer 23

Narcotics (opioids) – causes respiratory depression, NO cardiac affects. Morphine causes hypotension from histamine release
Act on mu receptor in CNS
Liver metabolism and kidney excretion
Avoid morphine and codeine in renal injury
Dilaudid is metabolized in liver but only small amount excreted in kidney. OK to use in AKI
Fentanyl and methadone = safest to use in ESRD
Demerol - meperidine
- SE→ Tremors, fasciculations, coma, seizures, avoid in patients with renal failure
- Avoid with MAOI, can cause hyperpyrexic coma→ serotonin release syndrome
- No histamine release
Fentanyl – no histamine release. Can give if pt has morphine allergy
Sufentinel – Most potent
Benzos + opioid has synergistic effects

Question 24

Benzos

Answer 24

Metabolized in liver
Binds GABA
-Versed (midazolam): short acting; crosses placenta
-Valium(diazepam) & Ativan (lorazepam): long acting

Overdose= flumazenil

Question 25

Serotonin syndrome

Answer 25

rigidity, tachycardia, sweating, hyperthermia, seizure

Question 26

Epidural & Spinal anesthesia

Answer 26

Epidural – Sympathetic denervation, only affects sensory, not motor.
- Causes vasodilation
- Lowers respiratory and cardiac complications post op vs IV narcotics. No effect on mortality
- Anesthetic is placed outside the dura, In epidural space
- Avoid insertion at T5 or higher, affects cardiac nerves  bradycardia
- Thoracotomy T6-T9
- Laparotomy T8-T10
- Morphine causes respiratory depression  use dilaudid
- Morphine epidural does not cause hypotension
- Lidocaine causes bradycardia and hypotension  Turn off epidural, give fluids, phenylephrine, and atropine if severe
- If leg numb: Turn down epidural rate
- CI to epidural – elevated intracranial pressure, hypertrophic cardiomyopathy, cyanotic heart disease, aortic stenosis, elevated ICP, systemic infection
Epidural hematoma – sudden back pain at epidural site, loss of sensation and motor in extremities. Loss of bowel bladder control. Dx: MRI, Tx: emergent laminectomy
Spinal headache – caused by CSF leak after spinal or epidural. Headache is worse with sitting up. Patients prefer to be supine. Tx: rest, fluids, caffeine. Blood patch if persists > 24 hours

Spinal anesthesia = motor and sensory blockade. Injected into subarachnoid space= intrathecal space. Must be injected below L2 to avoid spinal cord. Single shot.

Question 27

Predicators of major cardiac complications

Answer 27

Low-risk surgeries confer < 1% risk of myocardial infarction (MI) and include cataract surgery, breast surgery, and endoscopy.
Medium-risk surgeries confer a 1-5% risk of MI and include most head and neck surgeries, thoracic surgeries, abdominal surgeries, orthopedic surgeries, and carotid endarterectomy.
High-risk surgeries confer >5% risk of MI and include emergent operations, cardiac surgeries, and major vascular surgeries except carotid endarterectomy.

Pre-operative 12-lead ECG is recommended for patients with known coronary artery disease, arrhythmia, peripheral arterial disease, cerebrovascular disease, or other significant structural heart disease undergoing surgery that is associated with a medium to high risk of peri-operative MI.

Percutaneous angioplasty only – wait 2 weeks before surgery
Bare metal stent – 4 weeks before elective surgery
DES – 6 months
Wait 6 weeks after MI before elective surgery

Question 28

Mets/ cardiac evaluation

Answer 28

4 METs are climbing a flight of stairs, walking up a hill, walking on level ground at 4 mph, and performing moderate intensity work around the house.

Comorbidities with high risk of peri-op cardiovascular events
CHF (Highest risk), ischemic heart dz, CVA, DM, ESRD or AKI Cr > 2
If any above  figure out METS
- < 4 mets  slow walking, light effort on stationary bike  Need pharmacologic stress test
- > 4 mets  climb 1 flight of stairs without stopping, walking uphill 1-2 blocks  No need for testing

Question 29

Intubated and sudden rise in ETCO2

Answer 29

Intubated patient with sudden rise of ETCO2:
1. Hypoventilation
2. CO2 embolus
3. Malignant hypothermia
4. Capnothorax

MCC hypoventilation (tx= increase TV or RR)

Co2 embolus will cause transient rise of ETCO2 with quick fall of ETCO2

• CO2 embolus is most commonly associated with a DROP of end tidal CO2 (lack of blood flow to lungs)
  -CO2 embolus associated with hypotension

-High end tidal CO2 during mediastinal dissection (EG Nissen) is most likely capnothorax (pneumothorax due to pleural tear)

-Enlarge tear to avoid tension capnothorax
-Place red rubber catheter with one end into pleural tear and other end into abdomen (equalizes pressures)
-At end of procedure bring one end outside of abdomen and place to water seal while Valsalva administered
-Can also needle decompress intra-operatively – be sure to prep lower chest

Question 30

Intubated and sudden drop in ETCO2

Answer 30

Sudden drop of ETCO2: MC disconnected from vent
Also, PE or air embolism, or CO2 embolism; cardiac arrest (all have hypotension)

Air embolism: trendelenberg (head down) + left lateral decubitus position; hyperventilate

Question 31

ASA

Answer 31

ASA 1 healthy. 2 mild disease Controlled HTN, diabetes, smoker, 3 severe disease, hx of MI, uncontrolled HTN or DM, Controlled COPD. 4 severe disease with threat to life, unstable angina, decompensated CHF, ESRD, cirrhosis. 5, moribound patient, ruptured AAA, saddle embolus. 6 Donor

Question 32

Shoulder pain after abdominal laparoscopy

Answer 32

Induction of pneumoperitoneum stretches the diaphram, which irriates the phrenic nerve, which causes referred pain to the shoulder. C3-5= phrenic nerve

Question 33

Brachial plexus bloc now pleuritic chest pain, breathlessness, desaturates

Answer 33

Iatrogenic pneumothorax: pleuritic chest pain, dyspnea, hypoxemia
PUnctured apical pleura

Question 34

Perioperative Management Recommendations for Cardiac-Related Medications

Answer 34

-Beta-blockers: continue peri-operatively to reduce cardiac morbidity (can pause if bradycardia, hypotension)

-Aspirin: can continue throughout most elective surgical procedures

P2Y12 antagonists (clopidogrel, prasugrel, ticagrelor)
-Hold typically 1 week before elective surgery after at least 6 months of dual-antiplatelet therapy after percutaneous coronary intervention (at least 1 month if time-sensitive surgery)
-Stop clopidogrel at least 5 days before procedure (restart with loading dose)
-Stop ticagrelor 3-5 days before surgery

Warfarin: hold 5 days before procedure

Direct thrombin inhibitor (dabigatran)
-If Cr clearance >50 mL/min, stop 1 day before surgery in low risk bleeding; 2 days if high risk bleeding
-Cr 30-50: 2 days before for low risk bleeding, 5 days before for high risk bleeding

Factor Xa inhibitors (rivaroxaban, apixaban): 48 hours before surgery (24 hours if low risk bleeding); resume 24 hours after in low risk bleeding, 48-72 hours in high risk bleeding