Nagelhout -RESPIRATORY Flashcards
The ETT should not be directed
upward into the turbinates
What is choanal atresia?
Birth defect characterized by obstruction of the posterior nasal airway. May be life threatening in the obligate nose breathing newborn.
The respiratory mucosa lines the lower
2 thirds of the nose and consists of ciliated columnar epithelium with goblet cells that produce mucus.
The principal arterial supply of the nasal fossae arises from the
ophthalmic arteries through the anterior and posterior ethmoid branches
The sensory nerves from the upper respiratory tract come from the
ophthalmic nerve and the maxillary nerve
both are branches of cranial nerve V
Pharynx extends to
C6
Adult larynx extends from
C3-C6
Chief support of the larynx and it is the only bone
Hyoid bone
Furrow between the glossoepiglottic fold and the base of the tongue is
VALLECULAR EPIGLOTTICA
The largest cartilage is
Thyroid cartilage
In adults, narrowest portion is the opening between the
True vocal cords (aka cricoid opening or rima glottidis)
For children , narrowest portion of the larynx is the
cricoid cartilage
Recommended for the emergency establishment of an airway when both endotracheal intubation and mask ventilation are unsuccessful.
Cricothyrotomy
How is a transtracheal block performed?
performed by puncturing the cricothyroid membrane with a needle and
injecting a local anesthetic into the trachea.
Blood supply to the larynx is provided by the
superior thyroid artery (a branch of the external carotid artery) and the inferior thyroid artery (a branch of the thyrocervical trunk, which arises from the subclavian artery)
The trachea is lined by
pseudostratified ciliated columnar epithelium
The distance from the incisors to the larynx is approximately as is that from the larynx to the carina.
13 cm
Therefore the distance from the incisors to the carina is
approximately 26 cm (note the length markings on ETTs).
Nerve Supply to the Larynx
Both the superior and inferior laryngeal nerves are branches of cranial nerve X, the vagus nerve.
The trachea has a diameter of approximately
2.5 cm
The trachea extends down to the level of
T4–T5
Glottic Opening
• Opened by the
posterior cricoarytenoid muscles
Glottic Opening• Closed by the
transverse arytenoid and the lateral cricoarytenoid muscles
True Vocal Cords
• Lengthened by the
cricothyroid muscles
True Vocal Cords
Shortened by
thyroarytenoid muscles
The right bronchus takes a less
acute angle from the trachea, approximately whereas the
25 degrees,
Left bronchus takes off at
45 degrees.
Right lobes division
Upper 3
Middle 2
Lower 5
Left lobes division
Upper 4
Lower 4
Each successive division of the airways is referred to as a
generation
The lobar bronchi divide into the third generation of airways, called
segmental bronchi,
With succeeding generations
# of airway?____
Total Cross sectional area ?______
Airflow velocity decrease? ______
Increase in number airways
Larger cross sectional area
Decrease airflow velocity
How many generations before the alveoli?
20-25
By the 7th generation, the bronchioles size is
approximately 2mm
Bronchioles size in small airways
decreased to 1mm
The terminal bronchioles divide into the
respiratory bronchioles that are perfused by the pulmonary circulation and are the first place in the airway at which exchange of gas with the blood occurs.
The respiratory bronchioles divide into the several alveolar ducts that lead to circular spaced called
ATRIA
The lung volume at which small airways tend to close is called the
closing volume.
Obesity or chronic obstructive pulmonary disease (COPD), the closing volume
increases into the range of normal tidal breathing
Small pores in the alveoli, known as the serve to
pores of Kohn
Pores of Kohn serve to
allow collateral gas flow between alveoli and provide a mechanism of relief from gas stagnation from airway closure
What comprises the respiratory zone?
The respiratory bronchioles
Alveolar ducts, sacs
Alveoli comprise the respiratory zone
where gas exchange takes place.
What comprises the conducting zone?
All parts of the airway prior to this (nose to terminal bronchioles) conduct gas without exchanging gas with the blood and are referred to as the conducting zone.
The typical maximum number of approximately
300 million alveoli is reached by age 9 years.
There are three types of cells that form the alveoli: type I pneumocytesn; and
which are the structural cells
Type II pneumocytes, which produce
surfactant to reduce alveolar collapse from surface tension
Type III pneumocytes, which are
macrophages.
Contraction of the muscles of inspiration __________intrathoracic pressure
and causes the volume of the thoracic cavity to ________
lowers; increase.
This law explains that the increase in volume creates a reduction in pressure, which causes air to enter from the atmosphere.
Boyle’s law
Each half of the diaphragm is innervated by a branch of the phrenic nerve, which arises from the
C3, C4, C5
Spinal cord injuries above _____usually lead to dependence on mechanical ventilation.
above the level of C-5
During forced exhalation (e.g., with coughing and the clearing of secretions), What abdominal muscles are used?
Rectus abdominis, the transversus
abdominis, and the external and internal oblique muscles, are used
For air to move into the alveoli, alveolar pressure must be
less than atmospheric pressure
During forceful inspiration muscles used are
the sternocleidomastoid and scalene muscles contract in conjunction with the
diaphragm and intercostals.
When the diaphragm contracts during
spontaneous inspiration, it flattens and moves the abdominal contents downward ______intraabdominal pressure whilst_________intrathoracic
pressure.
raising ; lowering
Explain paradoxical movement of diaphragm?
When the normal diaphragm contracts (moving downward), the paralyzed diaphragm moves upward, and when the
normal diaphragm relaxes (moving upward), the paralyzed diaphragm moves downward, resulting in paradoxical movements
Lung compliance is defined as the
change in volume divided by the
change in pressure (V/P).
Static effective compliance describes
the pressure-volume relationship
for a lung when air is not moving;
Static compliance is decreased by conditions
that make the lung difficult to inflate, such ast)
fibrosis, obesity, vascular engorgement, edema, acute respiratory distress syndrome (ARDS), and external compression (e.g., that caused by tight dressings or a surgeon
leaning on the patient’s chest
Static effective compliance
tidal volume/ Plateau pressure - PEEP
It is important to note that compliance changes as
lung volume changes.
Static compliance is increased by
emphysema, which destroys the elastic tissue of the lung
When an alveolus is collapsed, a great increase
in pressure is necessary for inflation to begin.
At low volumes,.
more energy is required (more negative pressure, i.e., less compliant) to begin to
expand the lungs
At high volumes, the alveoli are almost at capacity, and
further changes in pressure result in less change in volume (less
volume per given pressure = less compliant).
Normal Static compliance
60 to 100 mL/cm H2O is considered normal.
The most useful clinical application of compliance measurement is in
monitoring trends to evaluate changing physical status or the effectiveness of PEEP or other treatment modalities.
Dynamic compliance is the
compliance of the lung when the air is
moving.
Can greatly decrease dynamic compliance.
Airway obstruction (e.g., that caused by bronchospasm or the presence of foreign bodies in the airway)
Dynamic compliance is calculated as the
tidal volume / peak inspiratory pressure − PEEP
This concept is often attributed to the law of
Laplace (P = T/r), which states that if surface tension (T) is constant, pressure (P) would increase as radius (r) decreases
Surfactant consists of
proteins and phospholipids, primarily, dipalmitoylphosphatidylcholine.
The classical application of Laplace described the concept of alveoli as distinct
balloon-like structures wherein pressure differentials can cause
alveoli to collapse and expel their gas into larger ones.
Prevalent cause of respiratory distress syndrome (RDS) in premature infants.
Lack of surfactant
is sometimes performed to determine
whether mature surfactant levels are present in the premature fetus
Amniocentesis
What indicates the amount
of mature surfactant ?
The ratio of lecithin to sphingomyelin (the L/S ratio
In the fetus, surfactant is not produced until approximately and
28 to 32 weeks of gestation
Fetal surfactant, Does not reach mature levels until approximately
35 weeks’ gestation.
Transpulmonary pressure is
the difference between intraalveolar pressure and intrapleural pressure
In laminar flow, the gas in the center of the stream moves
faster than that closer to the wall
because frictional resistance slows molecules near the vessel wall
Re =
pvd/n
= velocity of fluid flow, d = diameter of the vessel, p = density
of the fluid, and η = viscosity of the fluid
Products up to 2000 predicts
predict laminar flow;
Above 4000 predict
turbulent flow,
Transitional flow
2000-4000
True laminar flow occurs in
smaller airways
Turbulence is greatest in
large airways, and turbulence caused by branching of the airways produces
the breath sounds heard on auscultation
Resistance (R) to laminar airflow is directly proportional to the
length (l) of the
tube and inversely proportional to the fourth power of the radius (r).
Therefore doubling the radius of the tube decreases resistance by
16 (24)
Under normal circumstances, the greatest resistance to airflow resides in
medium-sized bronchi
Bronchodilators will reduce resistance to
airflow by
increasing the radius of the pathway, as predicted by Poiseuille.
The reduction in density is the conceptual basis for combining
helium with oxygen (“heliox”) to improve pulmonary gas distribution in obstructive lung disease
The volume of gas left in the lung after a maximal exhalation
The residual volume (RV)
The Closing capacity is the sum of the
closing volume plus the residual volume
The closing volume increases from approximately
30% of the TLC at age 20 years to approximately 55% at age 70 years.
%VD =
(PaCO2 −PECO2) PaCO2
Conditions PE what happens to dead space and ETCO2 such as pulmonary embolus,
increase the alveolar dead space and can abruptly decrease the end-tidal CO2 (ETCO2) levels monitored with capnography.
