Week 3- Airway & Airway Equipment Flashcards
in a person with normal lungs, breathing can be performed exclusively by
the diaphragm
in an adult, the orotracheal tube moved how much with head and neck flexion/extension
3.8 cm but as much as 6.4 cm
movement of the orotracheal tube in infants and children
displacement of even 1 cm can move the tube above the vocal cords or below the carina
a. length of adult mainstem bronchus before branching into lobar bronchi?
b. name some variations from that normal
a. 2.5 cm
b. 10% adults right upper bronchus departs from right main stem bronchus < 2.5 cm below carina & 2-3% of adults, the right upper lobe bronchus opens directly into the trachea, above carina
when lung compliance is reduced, what does the body do to achieve the same tidal volume (Vt)
large changes in pleural pressure
why is spontaneous respiratory effort the most sensitive clinical index of lung compliance
patients with low lung compliance breathe with smaller Vt and more rapidly
at what PaO2 values are carotid and aortic bodies stimulated
60-65 mmHg
T or F: the response of peripheral receptors will reliably increase the ventilatory rate or minute ventilation to herald the onset of hypoxemia during general anesthesia and recovery
F… it does not reliably do that
3 etiologies of hyperventilation
- arterial hypoxemia
- metabolic acidemia
- central etiologies
examples of illnesses that may cause hyperventilation
intracranial HTN, hepatic cirrhosis, anxiety, pharmacological etiologies
increases in dead space affect:
increases in physiologic shunt effects:
CO2 elimination
arterial oxygenation
alveolar to dead space ratio:
a. positive pressure ventilation
b. spontaneous ventilation
a. 1:1
b. 2:1
why should minute ventilation during mechanical vent support be greater than during spontaneous ventilation
to achieve same PaO2 because the ratio of alveolar to dead space is 2:1 and during positive pressure ventilation, the ratio of alveolar to dead space is 1:1
what causes the difference between PaCO2 anD PETCO2
Due to dead space ventilation and the most common cause is decreases cardiac output
calculating shunt fraction tells you
the lungs efficiency in oxygenating the arterial blood
what takes into account the contribution of mixed venous blood to arterial oxygenation
index of oxygenation
what happens when functional lung capacity is reduced
lung compliance falls (causing tachypnea) and venous admixture increases, creating arterial hypoxemia
when should preoperative pulmonary tests be administered
to ascertain the presence of reversible pulmonary dysfunction (bronchospasm) or to define severity of advanced pulmonary disease
how long before surgery should smokers be advised to quit and why
2 months, the decrease postop pulmonary complications (PPCs)
what body area causes the highest risk for PPCs
nonlaparoscopic upper abdominal operations and lower abdominal and intrathoracic operations
most important postoperative prevention of PPCs
early ambulation
describe the thorax
shape: truncated cone
sternal angle at horizontal plane and passes thru vertebral column at T4 and T5
what does the horizontal plane of chest separate
superior and inferior mediastinum
during ventilation, where do the predominant changes in thoracic diameter occurs
in the anterioposterior direction in the upper thoracic region and in lateral or transverse direction of lower thorax
what fatigues the muscles of ventilation
inadequate oxygen, poor nutrition, increased work secondary to COPD with gas trapping and airway resistance
ventilatory muscles
diaphragm
intercostal muscles
abdominal muscles
cervical strap muscles
sternocleidomastoid muscles
large back and intervertebral muscles of the shoulder girdle
what happens when work of breathing increases
ab muscles assist with rib depression and increase intra-abdominal pressure to facilitate forced exhaustion causing the “stitch” feeling
what is a “side stitch caused by”
forced exhalation during increased work of breathing
during an increased work of breathing, what muscles assist and what do they do
cervical strap muscles elevate the sternum and upper portions of the chest to optimize the dimensions of the thoracic cavity
when you are at Vmax of breathing what muscles assist
large back and paravertebral muscles of shoulder girdle
most powerful muscles of expiration
abdominal wall muscles
the muscle that assists with =coughing
abdominal
what do fatique-resistant fibers of lungs do
50% of diaphragmatic muscle fibers
endurance phenomenon- slow twitch response to electrical stimulation requiring enough force to generate subatmospheric pressure in intrapleural space
the unique dual function of lungs
endurance and explosive
in lung fibers, what creates endurance units
high oxidative capacity of the fibers
the most important inspiratory accessory muscle
cervical strap muscles
what is an example of when the cervical strap muscles may become to primary inspiratory muscles
c-spine cord transection
why do the visceral and parietal pleurae oppose each other
create a potential intrapleural space where the pressure decreases when diaphragm descends and rib cage expands
the air is left after passive expiration Is called
functional residual capacity (FRC)
subambient pressure at FRC
-2 to -3 mmHg
the 3 lung parenchyma categories and what they do
- conductive airways- gas transport NO gas exchange (trachea, mainstem bronchi, bronchioles)
- transitional airways- gas movement &limited gas diffusion and exchange
- smallest airways- gas exchange
the # of alveoli by age 8 or 9 vs at birth
300 million vs 24 million
the surface area in the lungs for gas exchange
70 m^2
compare right vs left mainstem
right= > diameter than left, 25 degree angle from the trachea
left= < in diameter and 45 degree angle from trachea
the angle of the right and left mainstem in kids < 3 years old
55 degrees
in a supine patient, why is aspiration most likely it RUL bronchus
RUL bronchus dives almost directly posteriorly at ~ 90-degree angle from the right main stem
left main stem bronchus length before branching the LUL and lingula
5 cm
last airway component that is incapable of gas exchange and its size?
1 mm and terminal bronchioles
first site of gas exchange when descending airway
respiratory bronchioles
describe the final division of the alveolar ducts
they terminate in alveolar sacs that open into alveolar clusters
two functions of the alveolar-capillary membrane
- transport respiraoptyr gases (O2 & CO2)
- production of a variety of local and humoral substances
the alveolar capillary membrane produces ________ and is responsible for ____________
surfactant
electrolyte balance
why do we need surfactant
so lung doesn’t collapse
2 major circulatory systems involving the lungs
pulmonary vascular system
bronchial vascular system
the pulmonary vascular system delivers_________ blood from the ___________ to the ___________ via ___________
mixed-venous
right ventricle
pulmonary capillary bed
two pulmonary arteries
describe what happens after the gas exchange in the pulmonary capillary bed
blood returned to left atrium via 4 pulmonary veins
what system provides metabolic and oxygen needs of alveolar parenchyma
Pulm. capillary system
what system provides oxygen to the conductive airways and pulmonary vessels
bronchial arterial system
a “normal” shunt of 2-5% total cardiac output occurs where
anatomic connections between bronchial and pulmonary venous circulations
the response of the lungs to external forces is governed by what two things?
- ease of elastic recoil of the chest wall
- resistance to gas flow in airways
the FRC represents what about gas volume in the lungs
the gas volume in lungs when outward forces= inward forces
in an upright adult, the difference in intrapleural pressure from top to bottom of lung
7 cm H2O
what is the “simplified” difference between restrictive lung disease and obstructive lung disease
R: trouble getting air in
O: trouble getting air out
decreased lung complaince in restrictive pulmonary diseases results in ________ FRCs
smaller
what would the graph of the sum or pressure-volume relationships of the thorax and lung look like
sigmoidal curve
T or F: CPAP cannot increase the FRC
F- It Can! :)
most common examples of diseases with high lung compliance `
Chronic obstructive lung disease and acute asthma
what happens to FRC and Vt in restrictive disease
less FRC and less Vt– think about it… cant get air in!
in restrictive lung disease, how does the body compensate for changes in FRC and Vt
increases RR
what happens to FRC in obstructive lung disease and why
increases because lacking elastic recoil
how can compliance and inspiratory elastic work be measured
via a single breath
by measuring airway pressure (Paw), intrapleural (Ppl) pressure and Vt
t/f: there is laminar flow but no turbulent flow in respiratory tract
F: there is both in the respiratory tract
the velocity of laminar flow and what it sounds like
zero at wall and max at center
usually inaudible
flow that is usually audible
turbulent flow
in laminar flow, relationship between resistance and gas flow rate
inversely proportional
4 conditions that change laminar flow to turbulent flow
- high gas flow
- sharp tube angles
- branching in tube
- decreased tube diameter
in turbulent flow, the relationship between resistance and gas flow rate
resistance increases in proportion to flow rate
things that can increase airway resistance (name 6)
- bronchospasm
- mucosal edema
- mucous plug
- epithelial desquamation
- tumors
- foreign bodies
changes in the aging lung and chest wall
- decreased lung recoil creating increased residual volume and FRC
- chest wall compliance diminishes this increasing work of breathing
- decreased muscle mass
respiratory muscle strength decreases with aging and is strongly correlated with
nutritional status and cardiac index
with aging, what happens to the respiratory centers in the CNS
& in what situations would their ventilatory response be diminished
decreases sensitivity to hypoxemia and hypercapnia
HF, airway obstruction, pneumonia
define breathing
act of inhaling and exhaling
define ventialtion
movement of gas in and out of lungs
________ occurs when energy is released from organic molecules
respiration
Humans breath to __________ and __________ to _____________
ventilate
ventilate
respire
Define eupnea
continuous inspiration and expiration movement without ionterruption
define apnea
no breathing, no ventilatory effort
define apneustic ventilation and give an example
cessation of ventilatory effect with lungs filled to total lung capacity–> example is when harvesting lungs for donation, will fill lungs to capacity and then clamp to remove
define BIOT
ventilatory gaps interposed between periods of ventilation aka agonal breathing
where where the most basic ventilatory control centers in brain
medulla oblongata
the inspiratory centers that reside in the __________ are located in the _________
dorsal respiraotyr group (DRG)
dorsal medullary reticular formation
the source of ventilatory rhythmicity/ the pacemaker of the respiratory system
DRG
the expiratory coordinating center
ventral respiratory group (VRG)
where is the VRG located
ventral medullary reticular formation
what do the peripheral chemoreceptors vs the CNS receptors respond to
PC: lack of O2
CNS: changes in PCO2, pH, acid-base disturbaces
what are the peripheral chemoreceptors composed of and where are they located
carotid and aortic bodies
cartoid= bifurcation of the common carotid artery (predominantly ventilatory effects)
aortic= scattered about aortic arch and branches (predominantly circulatory effect)
how does neural output from the carotid bodies reach the central respiratory centers
the afferent glossopharyngeal nerves
carotid bodies are stimulated by ____________ and stimulate the central receptors to increase ___________
decrease in PaO2 and pHa (NOT saturation)
minute ventilation
80% of ventilatory response to inhaled CO2 originates where
central medullary centers
acid-base regulation is related primarily to
chemosensitive receptors in the medulla
what is a normal PFT
depends on size/height of individual
why do we put a patient on 100% oxygen prior to intubation
to de-nitrogenate them. this buys time when you have a difficult airway
what is VQ
ventilation and perfusion–> how well its working
what is tidal volume (Vt)
&
What are normal values
volume of gas that moves in/out of lungs during quiet breathing
6-8 mL/kg
what happens to Vt when there is decreased lung compliance
Vt decreases due to reduced ventilatory muscle strength
what is vital capacity?
&
what are the normal values
correlates with deep breathing and effective coughing
60 mL/kg
what happens to vital capacity in restrictive lung diseases
decreased
examples when vital capacity may be reduced
pleural effusion, pneumothorax, pregnancy, large ascites, ventilatory muscle weakness
what is the inspiratory capacity?
&
what happens to it in the presence of extrathoracic airway obstruction?
largest volume of gas that can be inspired from the resting expiratory level
decreased
what is residual volume
gas remaining within the lungs at end of forced maximal expiration
the resting expiratory volume of the lung and is the primary determining of oxygen reserve in humans when apnea occurs
FRC
diseases that reduce FRC and lung compliance
- Pulm. fibrotic processes
- Acute lung injury
- Pulmonary edema
- Atelectasis
-pregnancy
-obesity
-pleural effusion
- posture
PAPA & POPP reduce FRC
what happens to FRC when a healthy patient is supine
decreases 10%
what is forced vital capacity (FVC)
volume of gas that can be expired as forcefully and rapidly as possible after maximal inspiration
what happens to FVC in restrictive and obstructive lung diseases
decreased in both
FVC values associates with PPCs
< 15 mL/kg
why is FEVt a meaure of flow
records volume of gas expired over time
what is forced expiratory volume (FEVt)
forced expiratory volume of gas over a given time interval during the FVC maneuver
what happens to FEVt values in obstructive/restrictive lung diseases
decreased in both
what is forced expiratory flow (FEF25-75%)
average forced expiratory flow during the middle half of the FEV maneuver
another name for the FEF25-75% test
maximum mid-expiratory flow rate
normal vakue for FEF25-75% for healthy 70 kg man
4.7 L/sec (or 280 L/min)
what is included in the upper airway
nasal and oral cavities
pharynx
larynx
trachea
principle bronchi
what is included in the laryngeal skeleton
3 paired and 3 unpaired (9 total) cartilages
what contains the vocal cords
laryngeal skeleton
what are the 2 muscle groups of the larynx and what do they do
extrinsic- move larynx as a whole
intrinsic- move the various cartilages
what nerve innervates the larynx
superior and recurrent laryngeal nerves, which are branches of the vagus nerve
the recurrent laryngeal nerves suplly all of the _____________ muscles of the larynx… with the exception of __________
intrinsic
cricothyroid muscle
trauma to what nerve group can result in vocal cord dysfunction
recurrent laryngeal nerves
unilateral damage to the recurrent laryngeal nerve can cause…
causes hoarseness makes aspiration more likely and could cause airway obstruction
bilateral injuiry to recurrent laryngeal nerves can cause:
complete airway obstruction d/t fixed cord adduction–> could be surgical emergency
where is the cricothyroid membrane
1-1.5 finger breaths below the laryngeal prominence (thyroid notch)
how would you place a cricothyrotomy
inferior 1/3 and directed posteriorly
describe the trachea of an adult
- 15 cm
- 17-18 C-shaped cartilages w/ a membranous posterior aspect overlaying esophagus
- 1st ring is anterior to the 6th cervical vertebra
what spinous process lines up with the carina
T5
lt airway management accounts for what % of anesthetic deaths
2.3-16.6%
is it safe for a patient to chew gum before surgery? why or why not
chewing gum increases hydrochloric acid secretion which increases gastric content and if that ends up in the lungs, it can cause a chemical pneumonitis
what is the 3-3-2 rule
3 fingers between incisors
3 fingerbreadths from thyroid to mentum
several minutes of 100% O2 may support _____ minutes of apnea before desaturation would occur
8
explain mallampati classifications
class I- uvula, pillars, soft palate
class II- pillars, soft palate
Class III- soft and hard palate
Class IV- only hard palate
most common reason for not achieving FiO2
loose fitting mask
what is a laryngospasm
reflex closure of the vocal folds as a result of:
- foreign body
- saliva
- blood
- vomitus touching glottis
- light plane of anesthesia
non-cariogenic pulmonary edema is the result of
spontaneous breath against a closed glottis
how to treat laryngospasms
- remove the offending stimulus
- continuous positive airway pressure
- deepening of anesthesia
- succinylcholine
what should cuff of the supraglottic airway be blown up to
to create a seal that allows positive pressure ventilation up to 20 cm of H2O pressure
how to decide what size LMA
the largest size that will fit in the mouth comfortably
T or F: The LMA protects the trachea from regurgitation
F- it does not
high risk for aspiration with LMA
- obese
- trendelenberg
- upper abdomen surgery
- intraperitoneal insufflation
- positive pressure ventilation > 20 mmHg
- full stomach
- GERD
- Bowel obstxn
when should SGA be pulled
either fully awake or deeply anesthetized NOT in between (could spasm)
what two things MUST you have to intubate
suction and oxygen
provides sensory innervation from the level of the vocal cords to the underside of the epiglottis
the finternal branch of the superior laryngeal nerve (branch of vagus)
stimulation of the internal branch of the superior laryngeal nerve (branch of the vagus) can cause
vagal response: laryngospasm, bradycardia, HTN
when is the miller blade considered a better option
pt with small mandibular space, large incisors, and large epiglottis
when is macintosh blade considered better option
when there is little room to pass the tube
placement of a Mac blade and what is the shape
in vallecula and curved
what can you do to confirm ETT placement
- visualize ETT thru cords
- listen to breath sounds (left first)
- check EtCO2
- is there condensation in the tube
- is there chest rise
- could listen to belly too
what size ETT for:
a. women
b. men
a. 7
b. 8
extubation criteria
- return of consciousness
- spontaneous respiration
- resolution of NM blockade- 5 sec
- follows commands
- 5-sec head lift
- sustained hand grasp
- spontaneous Vt > 6 cc/kg
- negative inspiratory pressure > 20 cm H20
define difficult airway per ASA
the situation in which the conventionally trained anesthesiologist experiences difficulty with intubation, mask ventilation, or both
evaluation of a difficult airway directs the clinician to enter the ASA algorithm at what 2 points
awake intubation
or
intubation attempts after induction of general anesthesia
if a difficult airway, when would you consider regional
- superficial surgery
- minimal sedation needed
- anesthetic may be provided with local infiltration
if a difficult airway, when would you NOT consider regional anesthesia
- cavity-invading surgery
- significant sedation needed
- extensive neuraxial local anesthesia required
- risk of intravascular injection/ absorption is high
- poor airway access
- surgery cannot be stopped once begun
6 steps of awake airway management
- explain why to pt
- explain the procedure
- sedation for decreased anxiety (benzo)
- may administer lidocaine or cocaine to decrease gag reflex - anti-sialagogues (decrease saliva)
- vasoconstrict nasal passage
- supplemental O2 during
airway medication prep that may cause methemoglobinemia and what is it treated with
cetacaine spray (benzocaine + tetracaine, butyl aminobenzoate, benzalkonium chloride, and cetydimethyl ammonium bromide)
treat with methylene blue
nerves of nasal cavity
greater and lesser palatine nerves and anterior ethmoidal nerve (branches of trigeminal nerve (CN V))
nerves of oropharynx
branches of vagus, facial, and glossopharyngeal nerves
nerves of the hypopharynx, larynx, trachea
superior laryngeal nerve block
contraindications to fiberoptic bronchoscopy
- hypoxia
- excessive airway secretions (that you cant fix)
- upper/lower airway bleeding (that you cant fix)
- local anesthetic allergy (for awake attempts)
- inability to cooperate (for awake attempts)
in fiberoptic bronchoscopy, which route is easiest: oral or nasal
nasal
glidescope laryngoscope blade angle
60 degrees
complications of retrograde wire intubation
- bleeding
- subQ emphysema
- pneumomediastinum
- breath-holding
- catheter traveling caudad
- trigeminal nerve trauma
- pneumothroax
can you use an LMA to pass an ETT
yes, a 7.0 ETT can pass thru #5 LMA
Can’t intubate, can’t ventilate situation– last resort option
percutaneous emergency airway access (PEAA)
Ventilatory muscles include
- The diaphragm
- The intercostal muscles
- Abdominal muscles
- cervical straps
- sternocleidomastoid muscle
- Large back and intervertebral muscles of shoulder girdle
-endurance muscle
When you have a C-spinal cord transaction, the __________ muscles become your primary inspiratory muscles.
Cervical strap
** diaphragm function is impaired
C-pine injury patients can still breath but they can’t _________.
Cough out secretions
**they end up with pneumonia. They can’t do the work of breathing that a normal healthy person could.
The _____________ muscles, active even during restful breathing, are the most important inspiratory ACCESSORY muscles.
Cervical strap
In an intact respiratory system, the expandable lung tissue fills the ______________.
Pleural cavity
The volume of gas remaining in the lungs at passive end-expiration.
Functional residual capacity
Lung Parenchyma can be subdivided in 3 categories:
- Conductive airways
- Transitional airways
- Respiratory airways
Compliance and inspiratory elastic work can be measured by:
Airway pressure (Paw)
Tidal volume (TV)
Intrapleural (Ppl)
Primary determinant of O2 reserve when apnea occurs
FRC
May be used to quantify the degree of pulmonary restriction
FRC
