This document provides information on the anatomy and physiology of the pediatric respiratory system. It discusses the differences between the upper and lower respiratory tract in children. Key points include that the nasal passages, sinuses, and larynx are narrower in children, making them more vulnerable to infection. The trachea and bronchi are also smaller with less developed cartilage and muscle. This makes the lower respiratory tract more prone to obstruction. The document also covers respiratory rates, breath sounds, percussion findings, and common respiratory disorders in pediatrics.

1. Anatomy & Physiology
of the respiratory system in children
prof. Pavlyshyn H.A., MD, PhD

2. Respiratory system
• The respiratory system is divided
into two parts: upper and lower
respiratory tract;
• The border of this division is the
lower edge of the cricoid cartilage.
• Upper respiratory tract includes
the paranasal sinuses, nasal cavity,
pharynx and the Eustachian tube and
other parts;
• Lower respiratory tract includes
the trachea, bronchi, bronchial and
alveolar capillary.

3. Anatomical characteristics
Upper respiratory tract
• The nose, nasal passages (airways), sinuses infancy are
comperatively narrow + Mucosa is rich for vascular tissue } →
that makes child vulnerable to infection and oedema;
• Infection, swelling of the nasal cavity and nasal congestion
contribute more narrow or blocked of nasal airways, causing
difficulty in breathing and sucking.
• There are not inferior (lower) nasal passages(until 4 years) and
as a result rarely epistaxis in infants;
• Nasolacrimal duct is short, the opening valve, hypoplasia valve may be the cause
of conjunctivitis with upper respiratory tract infection
• Development sinuses of infants continued after 2 years of age and finished to 12
years; the maxillary sinuses is usually present at birth; the frontal sinuses begin to
develop in early infancy; Babies can suffer from sinusitis; the ethmoid, maxillary
sinuses are most vulnerable to infection.

4. • Larynx is located on level the 3-4th (neck) vertebrae;
•Vocal and mucous membranes are rich blood vessels and lymphatic tissue, prone to
inflammation, swelling, due to babies suffering from laryngitis (viral croup), airway
obstruction, inspiratory dyspnea;
Upper respiratory tract in children

5. • The trachea is
short;
• Tracheal and
bronchial passes in
children is relatively
small, cartilage soft,
the lack of elastic tissue
Trachea
Bronchi Tubes
Bronchiole
Alveoli
LRT – vulnerable,
easy to cause
airway
narrowing and
obstruction
Anatomical characteristics
Lower respiratory tract
Right bronchus more
straight, like a direct extension
of the trachea (causing the
right lung atelectasis or
emphysema);
Left bronchus is the
separation from the trachea;
The bronchus is divided
into inter-lobe bronchus,
segmental bronchus,
bronchioles.
Bronchioles - no
cartilage, smooth
muscle imperfect
development, mucosa
rich in blood vessels,
mucous glands
hypoplasia, lack of
secretion of mucus,
poor mucociliary
movement;

6. Anatomy and physiology
• The ribs are cartilaginous and perpendicular relative to the vertebral
column (horizontal position), reducing the movements of the rib cage.
• The infant chest wall is remarkably compliant and compliance decreases
with increasing age.
– The orientation of the ribs is horizontal in the infant; by 10 years of
age, the orientation is downward.

7. The mecanizm of breathing
• Contraction of
external
intercostal
muscles >
elevation of ribs &
sternum
• > increased front-
to-back dimension
of thoracic cavity
↓
Contraction of
diaphragm:
diaphragm moves
downward
>increases vertical
dimension of
thoracic cavity
↓
lowers air pressure in lungs
 air moves into lungs

8. Anatomy and physiology
• The intercostal muscles and
accessory muscles of
ventilation are immature.
As a result, children are more
reliant on the diaphragm for
inspiration.
• Increased respiratory effort
causes subcostal and sternal
recession, and the mechanical
efficiency of the chest wall is
reduced.

9. The considerable differences in respiratory
physiology between infants and adults
explain why infants and young children
have a higher susceptibility to more
severe manifestations of respiratory
diseases, and why respiratory failure is
common problem in neonatal and pediatric
intensive care units.
The appreciation of the peculiarities of
pediatric respiratory physiology is not only
essential for correct assessment of any ill
child, but also for correct interpretation of
any pulmonary function test performed in
this population.
Summary

10. An average respiratory rate at rest of the
child of different age is:
• newborn 40-60 per minute,
• infant at 6 months 35-30 per minute,
• at 1 year 30 per minute,
• 5 years 25 per minute,
• 10 years 20 per minute,
• 12-18 years 16-20 per minute.

11. Disorders of the respiratory rate
• Tachypnea is the increase of the RR
(Interstitial, vascular and multitude of diseases, anxiety)
• Bradypnea is the decrease of the RR
(Narcotics, raised intracranial tension, myxedema)
• Dyspnea is the distress during breathing
• Apnea is the cessation of breathing

12. Disorders of the respiratory
depth
• Hyperpnea is an increased depth.
• Hypoventilation is a decreased depth
and irregular rhythm.
• Hyperventilation is an increased rate
and depth.

13. Pathological respiration
• Seesaw (paradoxic) respirations: the chest falls
on inspiration and rises on expiration. It is usually
observed in respiratory failure of third degree, RDS;
• Cheyne-stokes breathing: cyclical increase and
decrease in depth of respiration (CHF, cerebrovascular
insufficiency)
• Kussmaul: slow deep breathing, hyperventilation,
gasping and labored respiration (Ketoacidosis)
• Biot's breathing: totally irregular with no
pattern (CNS injury)

14. Percussion
• Resonant sounds are low pitched, hollow
sounds heard over normal lung tissue.
• Flat or extremely dull sounds are normally
heard over solid areas such as bones.

15. Percussion
• Percuss the lung fields, alternating, from top to
bottom and comparing sides
• Percuss over the intercostals space.
• Keep the middle finger firmly over the chest wall
along intercostals space and tap chest over distal
interphalangeal joint with middle finger of the
opposite hand.
• The movement of tapping should come from the wrist.
• Tap 2-3 times in a row.

16. Percuss the chest all around. Stand back, have the
patient cross arms to shoulder. This maneuver
will wing the scapula and expose the posterior
thorax.
• Then move to the front and
percuss anterior chest , clavicles
and supraclavicular space.
Then, have the patient keep their
hands over head and percuss axilla.
Percussion

17. Percussion
• The lung is filled with air (99% of lung
is air).
• Percussion of it gives a resonance. This
step helps identify areas of lung devoid
of air.
•Appreciate the dullness of the left
anterior chest due to heart and right
lower chest due to liver.
• Note the hyper-resonance of the left
lower anterior chest due to air filled
stomach.
• Normally, the rest of the lung fields are
resonant.

18. The pathological dullness is heard in
cause of
• Dull or thud like sounds are normally heard over
dense areas such as the heart or liver.
• Dullness replaces resonance when fluid or solid
tissue replaces air-containing lung tissues, such
as occurs with pneumonia, pleural effusions
(hydro-, haemothorax), or tumors.
• Decreased resonance is noted with pleural
effusion and all other lung diseases.

19. The hyper resonant sounds is heard in
cause of
• Hyper resonant sounds that are louder and
lower pitched than resonant sounds are normally
heard when percussing the chests of children and
very thin adults.
• Hyper resonant (ban-box) sounds may also be
heard when percussing lungs hyperinflated with
air, such as emphysema of lungs, patients with
COPD, asthma, asthmatic bronchitis.
• An area of hyper resonance on one side of the
chest may indicate a pneumothorax.
Increased resonances can be noted either due to lung distention as seen
in asthma, emphysema or due to Pneumothorax.

20. • Tympanic sounds are hollow, high, drum
like sounds.
• Tympany is normally heard over the
stomach, but is not a normal chest sound.
• Tympanic sounds heard over the chest
indicate excessive air in the chest, such as
may occur with pneumothorax.
The tympanic sounds is heard
in cause of

21. Anatomy of lobes of lungs

22. • Listen to at least one complete respiratory cycle at each site.
• First listen with quiet respiration. If breath sounds are inaudible,
then have him take deep breaths.
• First describe the breath sounds and then the adventitious sounds.
Auscultation
method of exam
• Auscultate the lungs from the apices,
middle and lower lung fields posteriorly,
laterally and anteriorly.
• Alternate and compare sides.

23. • Assess length of inspiration and expiration. Listen for the
pause between inspiration, expiration.
• Compare the intensity of breath sounds between upper and
lower chest in upright position.
• Note the presence or absence of adventitious sounds.
Auscultation
method of exam
• Note the intensity of breath sounds
and make a comparison with the
opposite side.

24. Begin by auscultation
the apices of the
lungs,
moving from side to
side and
comparing as you
approach the bases.
If you hear a suspicious
breath sound,
listen to a few other
nearby locations and
try to delineate its extent
and character.
• To assess the posterior chest, ask
the patient to keep both arms crossed
in front of his/her chest, if possible.
• It is important that you
always compare what you
hear with the opposite side.

25. Normal breath sounds
• tracheal, bronchial, broncho-vesicular and vesicular sounds.
Breath sounds are described by:
• duration (how long the sound lasts),
• intensity (how loud the sound is),
• pitch (how high or low the sound is), and
• timing (when the sound occurs in the respiratory cycle).

26. Breath sounds can be divided into the
following categories:
Normal
Abnormal Adventitious
tracheal absent/decreased crackles (rales)
vesicular bronchial wheeze
bronchial rhonchi
bronchovesicular stridor
pleural rub
mediastinal crunch
(Hamman's sign)

27. • Bronchial sounds are present over the large airways in the
anterior chest near the second and third intercostal spaces
(trachea, right sternoclavicular joints and posterior right
interscapular space);
• These sounds are more tubular and hollow-sounding than
vesicular sounds, but not as harsh as tracheal breath sounds.
• Bronchial sounds are loud and high in pitch with a short
pause between inspiration and expiration (inspiration and
expiration are equal); expiratory sounds last longer than
inspiratory sounds.
Normal breath sounds

28. The Bronchial Breath Sound
has the following characteristics :
• An I:E Ratio : 1:1 or 1:1 1/4 with a pause in
between inspiration & expiration
• Thoracic Geography : over the manubrium of the
sternum
• Sound Characteristics : high pitched, tubular,
hollow sound
• Indication: that an area of consolidation exists -
pneumonia, atelectasis, fluid infiltration

29. The Bronchovesicular
Breath Sound
has the following characteristics :
• An I:E Ratio : 1:1 or 1:1 1/4 with a pause in
between inspiration & expiration
• Thoracic Geography : They are best heard in the
1st and 2nd ICS (anterior chest) and between the
scapulae (posterior chest) - over the main stem
bronchi
• Sound Characteristics : high pitched, tubular,
hollow sound
• Indication : an area of consolidation - pneumonia,
atelectasis, fluid infiltration

30. Abnormal breath sounds include:
• the absence of sound and/or
• the presence of sounds in areas where
they are normally not heard.
• For example, bronchial breath sounds are abnormal in
peripheral areas where only vesicular sounds should be
heard.
• When bronchial sounds are heard in areas distant from
where they normally occur, the patient may have
consolidation (as occurs with pneumonia) or
compression of the lung. These conditions cause the
lung tissue to be dense. The dense tissue transmits
sound from the lung bronchi much more efficiently than
through the air-filled alveoli of the normal lung.

31. Type Characteristic Intensity Pitch Description Location
Normal
tracheal loud high harsh; not routinely auscultated over the trachea
vesicular Soft low . most of the lungs
bronchial very loud high
sound close to stethoscope; gap
between insp & exp sounds
over the
manubrium
(normal) or
consolidated
areas
bronchovesicular Medium medium .
normally in 1st
& 2nd ICS
anteriorly and
between
scapulae
posteriorly;
other locations
indicate
consolidation
Abnormal
absent/decreased . .
heard in ARDS, asthma, ateletasis,
emphysema, pleural effusion,
pneumothorax
.
bronchial . . indicates areas of consolidation .
Summery

32. The term “adventitious”
breath sounds
• refers to extra or additional sounds that are
heard over normal breath sounds.
• crackles (or rales)
• wheezes (or rhonchi)
• pleural friction rubs
• stridor

33. Adventitious sounds
• Wheeze
• Stridor
• Crackles
• Pleural Rub

34. Crackles (or rales)
• Crackles are discontinuous, intermittent, nonmusical, brief,
"popping" sounds that originate within the airways.
• are caused by fluid in the small airways or atelectasis.
• Crackles may be heard on inspiration or expiration. The popping
sounds produced are created when air is forced through respiratory
passages that are narrowed by fluid, mucus or pus.
• Crackles are often associated with inflammation or infection of the
small bronchi, bronchioles and alveoli (pneumonia, atelectatic lung).
• Crackles are often described as fine (high pitched, soft, very brief),
coarse (low pitched, louder, less brief).
• Fine crackles are soft, high-pitched, and very brief. You can simulate this sound
by rolling a strand of hair between your fingers near your ear.
• Coarse crackles are intermittent "bubbling" sound somewhat louder, lower in pitch,
and last longer than fine crackles.

35. Wheeze Lung Sounds
• These are continuous, high pitched, hissing,
whistling or sibilant sounds.
• They are caused by air moving through airways narrowed by
constriction or swelling of airway or partial airway obstruction
(asthma, CHF, chronic bronchitis, COPD).
• Wheezes are sounds that are heard continuously during inspiration
or expiration, or during both inspiration and expiration.
• Wheezes that are relatively high pitched and have a shrill or
squeaking quality may be referred to as sibilant rhonchi. These
wheezes occur when airways are narrowed, such as may occur
during an acute asthmatic attack.
• Wheezes that are lower-pitched sounds with a snoring or moaning
quality may be referred to as sonorous rhonchi. Secretions in large
airways, such as occurs with bronchitis, may produce these sounds;

36. Rhonchi Lung Sounds
• These are low pitched, continuous, musical, snore-
like sounds that are similar to wheezes.
• They are caused by airway secretions and airway
narrowing.
• They usually clear after coughing.

37. Pleural friction rubs
• are low-pitched, grating, or creaking sounds that occur when
inflamed pleural surfaces rub together during respiration.
• More often heard on inspiration than expiration, the pleural
friction rub is easy to confuse with a pericardial friction rub.
• To determine whether the sound is a pleural friction rub or a
pericardial friction rub, ask the patient to hold his breath
briefly. If the rubbing sound continues, its a pericardial friction
rub because the inflamed pericardial layers continue rubbing
together with each heart beat - a pleural rub stops when
breathing stops.

38. Type Characteristic Intensity Pitch Description Location
Adventitio
us
crackles (rales)
soft (fine
crackles) or
loud (coarse
crackles)
high (fine
crackles ) or
low (coarse
crackles)
discontinuous, nonmusical, brief;
more commonly heard on
inspiration; assoc. w/ ARDS, asthma,
bronchiectasis, bronchitis,
consolidation, early CHF, interstitial
lung disease
may sometimes be
normally heard at ant.
lung bases after max.
expiration or after
prolonged
recumbency
wheeze high expiratory
continuous sounds normally heard
on expiration; note if monophonic
(obstruction of 1 airway) or
polyphonic (general obstruction);
assoc. w/ asthma, CHF, chronic
bronchitis, COPD, pulm. edema
can be anywhere over
the lungs; produced
when there is
obstruction
rhonchi low expiratory
continuous musical sounds similar to
wheezes; imply obstruction of larger
airways by secretions
.
stridor . inspiratory
musical wheeze that suggests
obstructed trachea or larynx;
medical emergency
heard loudest over
trachea in inspiration
pleural rub . insp. & exp.
creaking or brushing sounds;
continuous or discontinuous; assoc.
w/ pleural effusion or pneumothorax
usually can be
localized to particular
place on chest wall
mediastinal
crunch
.
not
synchronized
w/ respiration
crackles synchronized w/ heart beat;
medical emerg.; assoc. w/
pneumomediatstinum
best heard w/ patient
in left lateral
decubitus position
Summery