3) Induction

indications for intubation

hypoxia

maintain patent airway

protect from aspiration

need positive pressure ventilation

lung isolation

tracheobronchial tree suctioning

define shunt

perfusion without ventilation

define dead space

ventilation without perfusion

example of shunt

mucous plug in tube

example of dead space

breathing circuit

5 common causes of hypoxemia

decreased FiO2

hypoventilation

decreased diffusion capacity

V/Q mismatch

true or anatomical shunt

formula for partial pressure of O₂ in arterial blood (P_aO₂)

PaO2 = 102 - (0.33 x age)

what P_aO₂ is considered hypoxemia?

< 60mmHg

as ________ (________ ________) decreases, P_aCO₂ increases

ventilation, respiratory rate

P_aCO₂ for an anesthetized patient (mmHg)

30-35mmHg

if you needed serial measurements of arterial blood gas, where would you sample from?

A-line

maintaining a patent airway prevents obstruction as a result of…

loss of consciousness, edema, compression of the airway

protecting airway from aspiration prevents loss of consciousness due to…

drug overdose, head injury, anesthesia

how does positive pressure ventilation work?

increases pressure at the opening of the airway, driving air into the lungs

how do you achieve positive pressure ventilation?

ETT, LMA, double lumen tube, mask

what kind of patients would you expect need suctioning of tracheobronchial tree?

patients who can’t cough effectively (trauma or comatose)

when is an intubation considered emergent?

apnea

total airway obstruction

when is an intubation considered pressing?

impending respiratory failure (FiO2 <90%)

partial airway obstruction

pulmonary edema

clinical judgement

when is an intubation considered elective?

beneficial to patient but not essential for survival

signs of respiratory failure & impending fatigue

anxious look

dilated pupils, sweating (overactive sympathetic)

dyspnea or decreased talking

tripod position

mouth open for inhalation and dry lips

pursed lips, expiratory grunting, cyanotic lips

restless and fidgeting

what are indications for elective intubations in the OR?

control airway under general

prevent aspiration

muscle relaxation

surgery impairs gas exchange

>3hrs of general

a lot of non-airway attention

control CO2 level

predicted difficult airway

what kinds of procedures would you want to electively intubate to prevent the loss of control over airway?

neurological

ENT (lots of blood in airway)

what surgical positions would you want to electively intubate to prevent the loss of control over airway?

prone

lateral decubitus

180 bed turn

what patient population would you electively intubate to prevent aspiration?

diabetics with gastroparesis

pregnant

poorly controlled GERD

stomach/intestinal derangement

why would you want to electively intubate pts that undergo muscle relaxation?

protective airway reflexes are impaired

what kind of surgeries are expected to impair gas exchange?

thoracic

abdominal

what’s considered complicated scenarios requiring a great deal of non-airway attention?

unstable patient, massive blood loss

what specialty would you electively intubate because there’s a need for control of CO₂ level?

what’s the target CO₂ level and why?

neurosurgery

25mmHg improves visualization & control for surgeon

when is there a secondary need for a guaranteed airway?

inadequate ventilation with other means

sedation that causes complete airway obstruction

surgical procedure change after induction

major anesthetic/surgical complication

what major anesthetic/surgical complications would cause a secondary need for guaranteed airway?

respiratory paralysis bc of high/total spinal

toxic dose of local anesthetic

massive hemorrhage

regional anesthetic stops working

how can you assess for paralysis of respiratory muscles (diaphragm)?

wiggle fingers, C3,4,5 keeps diaphragm alive (phrenic nerve) and C6 moves thumb so if they can’t then diaphragm is next to be paralyzed

routes of intubation…

transtracheal, nasal, orotracheal

how does succinylcholine work?

remains at NMJ preventing depolarization

is succinylcholine an ACh agonist or antagonist?

agonist

why is succinylcholine typically used for RSI?

quick onset, 30-60sec

how long does succinylcholine act?

5-20min

after giving succinylcholine, what do you expect to observe in the patient?

muscle fasciculation

what terminates succinylcholine action?

pseudocholinesterase

what electrolyte do you need to check before giving succinylcholine? what’s the safe levels for usage?

potassium bc sux causes release of K+, 3.5-5.5

what kinds of patients have exaggerated release of K+ that would prevent you from giving succinylcholine?

burns, muscle injury, motor neuron disease

how does succinylcholine affect the heart in adults and peds?

bradycardia

adults: 2nd dose

peds: more susceptible, pretreat with atropine

are non-depolarizing muscle relaxants ACh agonists or antagonists?

antagonists at nicotinic ACh receptors

is pancuronium long or short acting and what nerve does it block?

long acting

vagus nerve

where is rocuronium and vecuronium metabolized and excreted?

metabolized in liver, excreted in urine

what are intermediate acting non-depolarizing muscle relaxants?

rocuronium, vecuronium, atracurium, cisatracurium

which NDMR do you have to reconstitue?

vecuronium

2 benefits of vecuronium

few side effects, predictable action duration

onset time of rocuronium

60-90sec

how is atracurium and cisatracurium metabolized?

ester hydrolysis and hoffman elimination

4 drawbacks of atracurium

histamine release, hypotension and tachycardia at high doses, possible toxic breakdown product = laudanosine

what are 2 benefits of cisatracurium

no histamine release, more potent than atracurium

mivacurium: duration of action, metabolism, and release of…

short acting

metabolized by pseudocholinesterase

some histamine release

3 possible scenarios of intubation outside of OR

trauma

uncooperative, combative

patients nearing respiratory failure (ICU)

side effects of opioids

nausea, bradycardia, hypotension

side effects of propofol

hypotension, injection site pain, myoclonus (high doses)

versed should be given in ________ increments

0.5-1mg

fentanyl should be given in ________ increments

25-50mcg

morphine should be given in ________ increments

1-3mg

propofol should be given in ________ increments

10-20mg

when would you do general anesthesia outside the OR?

if sedation isn’t adequate or preferred

examples of when to provide general anesthesia outside the OR

cerebral injury, acute epiglottitis, uncooperative patient

monitoring when outside OR

SpO2, ECG, BP, EtCO2

most important equipment to have when performing intubation outside OR

blade, ETTs, stylet

suction

ambu bag, mask