Session 6: Ventilation Under Anesthesia Flashcards
3 types of ventilation
bag mask
LMA
ETT
most common situation for mask ventilation
mask induction
after IV induction but before intubation
over-sedated pts who go apneaic
failed itubation
any other unexpected apnea
advantage of mask ventilation
non-invasive
non-traumatic
disadvantages of mask ventilation
hands are not free
airway not protected
difficult on certain pts
limited to 20cmH2O
difficult in field avoidance cases
predictors of difficult mask ventilation
Obesity (can cause airway obstruct)
Overbite (prominent)
Facial hair/beard
Facial/neck trauma
Foreign body
Edentulous
Pharyngeal abscess or mass
Airway swelling
types of airway swelling
airway trauma
epiglottitis
burn pts
ludwig’s angina
anaphylaxis
Ludwig’s Angina
bacterial infection in the mouth that causes airway swelling
causes of ineffective mask ventilation
- poor mask seal/not enough pressure
- soft tissue airway obstruction
- too much pressure in circuit
- APL valve closed too much = hard to inflate lungs
how to improve mask ventilation
- use oral/nasal airway
- doing jaw thrust w/double handed masking technique
difficult mask ventilation protocol step 1
- properly positioned w/airway aligned
difficult mask ventilation protocol step 2
- if you cant mask, place oral/nasal airway
difficult mask ventilation protocol step 3
- perform double handed technique w/oral airway
- need additional person to squeeze bag
- if you dont have additional person, use ventilator
difficult mask ventilation protocol step 4
- if 2 hand mask fail, place LMA
Difficult mask ventilation protocol step 5
- if LMA doesnt work, 2 options
- if paralyzed w/Roc, try to intubate while assitant draws up reversing dose of sugammadex (16mg/kg)
- if not paralyzed, wake them up (let propofol wear off)
Ventilator setup during difficult mask protocol
pressure control ventilation
stay under 20cmH2O
Options for potential difficult mask ventilation and intubation
- awake intubation w/bronchoscope
- CPAP preoxygenation w/RSI
- emergency tracheotomy
LMA relieves
all airway obstruction
creates effective seal in pharynx
LMA vs Mask ventilation
LMA more effective and efficient
LMA accomplishes everything a mask can do but anesthetist has free hands
LMA advantages
- more effective ventilation
- great backup ventilation for difficult pts (rescue device)
LMA disadvantages
- doesnt protect airway
- limited to 20cmH2O
- cannot use volume control vent setting
Using ventilator w/LMA risks
higher risk for atelectasis
reduce risk by using pressure support ventilation or assist ventilation
LMA vs Intubation
- LMA is less traumatic
- LMA does not require muscle relaxants
- LMA lowers risk of laryngospasm
when do you place an LMA
for every general anesthetic unless LMA placement is contraindicated
Absolute contraindications for LMA
(FGPLVHDN)
Full stomach
GERD/Hiatal Hernia/pregnancy/neonates
Paralysis needed
Laparoscopic Surgery
Ventilator needed (pt not spontaneously breathing)
Higher airway pressure needed
Difficult intubation suspected
Neck/pharyngeal pathology
Full stomach pt examples
not NPO
gastroparesis (delayed emptying)
- narcotics, diabetes, ozempic, intense pain
bowel obstruction
types of pts w/decreased lower esophageal tone
GERD
hiatal hernia
pregnant
neonates
surgery types that require muscle paralysis
inner abdominal
laparoscopic
hip replacement
cardiothoracic
when is the ventilator required
Muscle relaxants used
Brain surgery
Cardiothoracic surgery
Clear liquid NPO
2 hrs
non-clear liquid NPO
4 hrs
breast milk NPO
4 hrs
non-human milk NPO
6 hrs
baby formula NPO
6 hrsi
light meal NPO
6 hrs
normal meal NPO
8 hrs
chewing tobacco NPO
6 hrs
clear liquids
juice
tea
black coffee
water
jello
italian ice
pedialyte
jellow
non-clear liquid
juice w/pulp
milk
alcohol
coffee w/milk
broth w/fat
light meal
toast and clear liquids
normal meal
fried/fatty foods or meat
chewing gum
increases saliva production
increases volume of stomach liquids
does not impact stomach acidity
does not elevate risk of complications
treat like clear liquid meal
Gastroparesis
delayed gastric emtying
causes of gastroparesis
narcotic use
trauma
diabetes
neonates
pregnancy/labor
liver failure w/ascites
obese pts gastric emptying
have faster gastic emptying
larger gastric volumes
still considered full stomach
hiatal hernia
upper portion of stomach herniates through lower esophageal sphincter into esophagus
nissen fundoplication
treatment for hiatal hernia and gastric reflux
lower esophageal sphincter is strengthened by wrapping portion of stomach around the lower portion of esophagus
Relative Contraindications to LMA placement
Long procedures (3+ hrs)
Obese pts
Non supine positions
Long procedures w/LMA risk
atelectasis
pressure ischemia due to LMA cuff
LMA complications
Laryngospasm/Bronchospasm
Aspiration
Dislodged LMA
Biting tube
diagnose laryngospasm from LMA
sudden loss of CO2 (right after incision)
too light anesthesia
treat LMA laryngospasm
150mg propofol
follow w/succinylcholine if propofol doesnt work
how to prevent aspiration w/LMA
avoid LMA placement in GERD/full stomach pts
avoid excessive PPV (>20cmH2O)
how to treat aspiration from LMA
-succinycholine and intubation
-bronchoscopy to remove gastric contents in airway
-chest xray/pulmonary consult/ICU stay
LMA Size 1
5kg
LMA size 1.5
5-10kg
LMA size 2.0
10-20kg
LMA size 2.5
20-30kg
LMA size 3.0
30-70kg
LMA size 4
70-90kg
LMA size 5
> 90kg
Indications for Intubation
Full stomach pt
GERD/hiatal hernia
Paralytics needed
Laparoscopic
Ventilator needed
higher airway pressure needed
Long procedure
intubation disadvantages
more invasive/traumatic
sore throat
risk for laryngospasm on emergence
must paralyze pt
higher risk of bronchospasm on emergence
ways to avoid coughing on intubated pts
administration of muscle relaxants
heavier narcotic dosing
deep anesthesis (>1MAC)
Local anesthetic (lidocaine)
Difficult intubation predictors (11)
Mallampatic class 3 or 4 (M)
Hx of difficult intubation
Obesity
neck trauma
foreign body
airway swelling
long protruding incisors
prominent overbite
small mouth opening (2 finger brreaths)
short thyromental distance (3 finger breaths)
limited cervical spine ROM (<21 degree extension)
TMJ
ETT Murphy Eye
hole on the right side of the endotracheal tube
alternative path for ventilation in case of distal tube obstruction
ETT bevel
allows ETT to be rotated to slide more easily into airway
Oral RAE ETT
can bend at mouth for ENT surgery
Nasal RAW ETTs
placement requires nasal intubation
popular for jaw/dental surgery
Adult female ETT size
7.0-7.5
Adult male ETT size
7.5-8.0
obese adult ETT size
> =8.0
pediatric uncuffed ETT size
Age/4 +4
pediatric cuffed ETT size
1/2mm smaller than uncuffed
(Age/4 +4) - 0.5mm
right mainstem intubation
endotracheal tube more likely to go into right mainstem if inserted too deeply
right lung lobes
3l
left lung lobes
2