-
MAC:
- 1) minimum alveolar concentration= smallest concentration of inhalational agents which 50% of patients will not move with incision
- 1- Small MAC--> more lipid soluble= more potent
- 2- speed of induction is inversely proportional to solubility
- 3- nitrous is fastest but has high MAC (low potency)
-
Inhalational agents cause:
- 1) unconsciousness, amnesia, and some degree of analgesia
- 2) blunt hypoxic drive
- 3) most are associated with some degree of myocardial depression, increased cerebral blood flow, and decreased renal blood flow
-
NO2 (nitrous oxide):
- 1) fast
- 2) minimal myocardial depression
-
Halothanes-
- 1) slow
- 2) highest degree of cardiac depression and arrhythmias
- 3) least pungent (which is good for children)
- 4) Halothane hepatitis:
- 1- fever
- 2- eosinophilia
- 3- jaundice
- 4- increased LFTs
-
Enflurane
can cause seizures
-
Isoflurane
- 1) good for neurosurgery
- 2) higher cost
-
Sevoflurane
- 1) less myocardial depression
- 2) fast onset/offset
- 3) less laryngospasm
- 4) higher cost
-
Induction agents (slides to follow):
-
Sodium thiopental (barbiturate):
- 1) fast acting
- 2) Side effects:
- 1- decreased cerebral blood flow and metabolic rate
- 2- decreased blood pressure
-
Propofol
- 1) very rapid distribution and on/off
- 2) amnesia
- 3) sedative
- 4) Side effects:
- 1- hypotension
- 2- respiratory depression
- 5) not an analgesic
- 6) do not use in patients with egg allergy
- 7) metabolized in liver and by plasma cholinesterases
-
Ketamine:
- 1) dissociation of thalamic/limbic systems; places patient in a cataleptic state (amnesia, analgesia)
- 2) No respiratory depression
- 3) Side effects:
- 1- hallucinations
- 2- catecholamine release (increased carbon monoxide, tachycardia)
- 3- increased airway secretions
- 4- increased cerebral blood flow
- 4) contraindicated for patients with head injury
- 5) good for children
-
Etomidate:
- 1) fewer hemodynamic changes; fast acting
- 2) continuous infusions can lead to adrenocortical suppression
-
rapid sequence intubation:
- Can be indicated for:
- 1) recent oral intake
- 2) GERD
- 3) delayed gastric emptying
- 4) pregnancy
- 5) bowel obstruction
-
What is the last muscle to go down and 1st muscle to recover from paralytics?
Diaphragm
-
Whats the 1st muscle to go down and last to recover from paralytics?
neck muscles and face
-
Depolarizing agent:
Depolarizing agent- the only one is succinylcholine
-
Succinylcholine
- 1) fast, short acting
- 2) causes fasciculations at first
- 3) increased ICP, many side effects
- 4) Side effects:
- 1- malignant hyperthermia
- 2- defect in calcium metabolism
- 3- calcium released from sarcoplasmic reticulum causes muscle excitation- contraction syndrome
- 4- Side effects: 1st sign is increased end-tidal CO2, then fever, tachycardia, rigidity, acidosis, hyperkalemia
- 5) Tx: dantrolene (10mg/kg) inhibits Ca release and decouples excitation complex, cooling blankets, HCO3, glucose, supportive care
- 6) hyperkalemia- depolarization releases K
- 7) Do not use in:
- 1- burn patients
- 2- neurologic injury
- 3- neuromuscular disorders
- 4- spinal cord injury
- 5- massive trauma
- 6- acute renal failure
- 8) open angle glaucoma can become closed-angle glaucoma
- 9) atypical pseudocholinesterases- cause prolonged paralysis (asians)
-
Nondepolarizing agents:
- 1) inhibit neuromuscular junction by competing with acetylcholine
- 2) can get prolongation of these agents with:
- 1- hypothermia
- 2- hypercarbia
- 3- certain antibiotics
- 4- electrolyte abnormalities
- 5- myasthenia gravis
-
Cis-atracurium
- 1) undergoes Hoffman degradation
- 2) can be used in liver and renal failure
- 3) histamine release
-
Mivacurium
- 1) fast, short acting
- 2) degradation by plasma cholinesterases
- 3) histamine release
-
Rocuronium
- 1) fast, intermediate acting
- 2) hepatic metabolism
-
Pancuronium
- 1) slow acting, long lasting
- 2) renal metabolism
- 3) most common side effect: tachycardia
-
Reversing drugs for nondepolarizing agents (slides to follow):
-
Neostigmine:
- 1) counters nondepolarizing agents
- 2) blocks acetylcholinesterase
- 3) increases acetylcholine
-
Edrophonium
- 1) counters nondepolarizing agents
- 2) blocks acetylcholinesterase
- 3) increases acetylcholine
-
Atropine or glycopyrrolate
1) should be given with neostigmine or edrophonium to counteract effects of generalized acetylcholine overdose
-
Local Anesthetics:
- 1) work by increasing action potential threshold, preventing Na influx
- 2) can use 0.5cc/kg of 1% lidocaine
- 3) infected tissues hard to anesthetize secondary to acidosis
- 4) Length of action: bupivicaine > lidocaine > procaine
- 5) Epinephrine allows higher doses to be used, stays locally
- 1- No epinephrine with:
- a- arrhythmias
- b- unstable angina
- c- uncontrolled hypertension
- d- poor collaterals (penis/ear)
- e- uteroplaental insufficiency
- 6) Side effects:
- 1- tremors
- 2- seizures
- 3- tinnitus
- 4- arrhythmias
- (CNS symptoms occur before cardiac)
-
Amides:
- (all have an "i" in the first part of the name)
- 1) lidocaine
- 2) bupivicaine
- 3) mepivacaine
- 4) rarely allergic reactions
-
Esters
- 1) tetracaine
- 2) procaine
- 3) cocaine
- Increased allergic reactions secondary to PABA analogue
-
Narcotics (opiods)
- 1) Morphine, fentanyl, demerol, codeine
- 2) act on mu receptors
- 3) profound analgesia, respiratory depression (decreased CO2 drive), no cardiac effects, blunt sympathetic response
- 4) metabolized by the liver and excreted via kidney
- 5) Overdose of narcotic drugs--> Tx: Narcan
- 6) Avoid use of narcotics in patients on MAOIs--> can cause hyperpyrexic coma
-
Morphine:
- 1) analgesia
- 2) euphoria
- 3) respiratory depression
- 4) miosis
- 5) Side effects:
- 1- decreased cough
- 2- constipation
- 3- histamine release
- 6) active metabolites can build up in patients with renal failure
-
Demerol:
- 1) analgesia
- 2) euphoria
- 3) respiratory depression
- 4) miosis
- 5) Side effects:
- 1- tremors
- 2- fasciculations
- 3- convulsions
- 6) no histamine release
- 7) avoid in patients with renal failure--> can get buildup of normeperidine analogue and result in seizures (also need to be careful with the amount given)
-
methadone
stimulates morphine, less euphoria
-
Fentanyl
- 1) 80x strength of morphine (does not cross-react in patients with morphine allergy)
- 2) no histamine release
-
Sufentanil, alfentanil remifentanil
very fast-acting narcotics with short half-lives
-
Benzodiazepines
- 1) hepatically metabolized
- 2) Effects:
- 1- anticonvulsant
- 2- amnesic
- 3- anxiolytic
- 3- respiratory depression
- 4- not analgesic
-
Versed (midazolam):
- 1) short acting
- 2) contraindicated in pregnancy; crosses placenta
-
ativan (lorazepam):
long acting
-
valium (diazepam)
long acting
-
Overdose of benzodiazepines:
Tx: flumazenil (competitive inhibitor; may cause seizures and arrhythmias; contraindicated in patients with elevated ICP or status epilepticus)
-
Epidural:
- 1) causes sympathetic denervation
- 2) vasodilation
- 3)
- Morphine in epidural can cause: respiratory depression
- Lidocaine in epidural can cause: decreased heart rate and blood pressure
- 4) dilute concentrations allow sparing of motor function
- 5) Tx for acute hypotension and bradycardia:
- 1- turn epidural down
- 2- fluids
- 3- phenylephrine
- 4- atropine
- 6) T5 epidural can affect cardiac accelerator nerve
- 7) Epidural contraindicated with:
- 1- hypertrophic cardiomyopathy
- 2- cyanotic heart disease--> can get inadvertant spinal anesthesia
-
Spinal anesthesia
- 1) injection into subarachnoid space
- 2) spread determined by baricity and patient position
- 3) neurologic blockade is above motor blockade
- 4) Spinal contraindicated with:
- 1- hypertrophic cardiomyopathy
- 2- cyanotic heart disease
-
Caudal block:
- 1) through sacrum
- 2) good for pediatric hernias and perianal surgery
-
Epidural and spinal complications:
- 1) hypotension
- 2) headache
- 3) urinary retention
- 4) abscess/hematoma formation
- 5) neurologic impairment
- 6) High spinal--> respiratory depression
-
Spinal headaches:
- Tx:
- 1) rest
- 2) increase fluids
- 3) caffeine
- 4) analgesics
- 5) blood patch to site if persists >24 hours
- 6) headache gets worse sitting up
-
Perioperative complications (slides to follow):
-
CHF and renal failure:
associated with most postoperative hospital mortality
-
Postop MI:
- 1) may have no pain or EKG changes
- 2) can have:
- 1- hypotension
- 2- arrhythmias
- 3- increased filling pressures
- 4- oliguria
- 5- bradycardia
-
Patients who need cardiology workup:
- 1) angina
- 2) previous MI
- 3) shortness of breath
- 4) CHF
- 5) walks <2 blocks due to shortness of breath or chest pain
- 6) FEV1 <70%
- 7) aortic stenosis murmur
- 8) PVC >5/min
- 9) age >70
- 10) patients undergoing major vascular surgery
-
ASA Classes:
- I- healthy
- II- mild disease without limitation (controlled HTN, obesity, diabetes mellitus, significant smoking history, older age)
- III- severe disease (angina, previous MI, poorly controlled HTN, diabetes mellitus with complications, moderate COPD)
- IV- severe constant threat to life (unstable angina, CHF, renal failure, liver failure, severe COPD)
- V- Moribund (ruptured AAA, sadle pulmonary embolus, ascending aortic dissection resulting in heart failure)
- VI- donor
- E- emergency
-
what risk are most vascular surgeries considered?
most vascular procedures are considered moderate to high risk surgery
-
Biggest risk factors for post-op MI:
- 1) age >70
- 2) DM
- 3) previous MI
- 4) CHF
- 5) unstable angina
-
What is the best determinant of esophageal vs tracheal intubation?
end-tidal CO2
-
Intubated patient undergoing surgery with sudden transient rise in ETCO2
- 1) Dx: most likely alveolar hypoventilation
- 2) Tx: increase tidal volume (most likely due to atelectasis) or increase respiratory rate
-
Intubated patient with sudden drop in ETCO2
- 1) likely became disconnected from the vent
- 2) could also be due to pulmonary embolism or significant hypotension
-
Where should endotracheal tube be placed?
should be placed 2cm above the carina
-
What the most common PACU complication?
nausea + vomiting
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