This document discusses dyspnea, or shortness of breath, from both clinical and physiological perspectives. Clinically, dyspnea is a subjective experience that varies in intensity, while physiologically it involves the stimulation of pulmonary and extra pulmonary receptors. The document outlines various lung volumes and capacities and explores the potential mechanisms of dyspnea. It also examines the evaluation, diagnosis, and treatment of different causes of dyspnea. A thorough history, physical exam, and testing are needed to diagnose the underlying condition and guide management.

1. Lailmaah habibi8/7/2015

2.  Clinical : A subjective experience of breathing
discomfort that consists of (qualitatively)
distinct sensations that vary in intensity.
 Physiological: The stimulation of pulmonary
and extra pulmonary afferent receptors and the
transmission of afferent information to the
cerebral cortex, where the sensation is
perceived as uncomfortable or unpleasant

4. •the volume of air inspired or expired with each normal breath (about 500 ml).
The tidal volume
•the extra volume of air that can be inspired over and above the tidal volume with full
force (about 3000 ml).
The inspiratory reserve volume
•the maximum extra volume of air that can be expired by forceful expiration after end
of tidal expiration (about 1100 ml).
The expiratory reserve volume
•the volume of air remaining in the lungs after the most forceful expiration (about
1200 ml).
The residual volume

5. • The amount of air a person can breathe in (about 3500 ml).
The inspiratory capacity
• The amount of air remains in the lungs after normal expiration (about
2300 ml).
The functional residual capacity
• The maximum amount of air that can be expelled after first filling the
lungs to maximum and expiring to maximum (about 4600 ml).
The vital capacity
• The maximum volume to which the lungs can be expanded with the
greatest possible effort (about 5800 ml).
The total lung capacity

6.  " Dyspnea， a symptom， can be perceived
only by the person experiencing it and must be
distinguished from the signs of increased work
of breathing.

7.  The pathophysiology is poorly understood.
 There are no specialized receptors for dyspnea.
 Recent MRI studies have identified a few
specific areas in the midbrain that may mediate
perception of dyspnea
Mechanism of dyspnea

8. Dyspnea results when a
"mismatch" occurs in CNS
between afferent & efferent
signaling.
As the brain receives
afferent ventilation
information, it is able to
compare it to the current
level of respiration by the
efferent signals.
If the level of respiration is
inappropriate for the body's
status then dyspnea might
occur.

9.  A given disease state may lead to dyspnea by
one or more mechanisms, some of which may
be operative under some circumstances (e.g.
exercise) but not others (e.g.， a change in
position).
 An increase in breathing occurs normally
during exercise and a high altitudes

10.  Motor Efferents Disorders of the ventilatory
pump-most commonly， increased airway
resistance or stiffness (decreased compliance)
of the respiratory system-are associated with
increased work of breathing or the sense of an
increased effort to breathe

11.  Sensory Afferents
 Chemoreceptors
 Mechanoreceptors
 Metaboreceptors

12. chemoreceptor
stimulation
(Afferent)
mechanical breathing
abnormalities (Efferent)
perception of those two by
the CNS

13.  Acute anxiety or fear may increase the severity
of dyspnea either by altering the interpretation
of sensory data

15.  modified Borg scale or visual analogue scale
can be utilized to measure dyspnea
 at rest
 immediately following exercise
 or on recall of a reproducible physical task
such as climbing the stairs at home.

16.  An alternative approach is to gain a sense of
the patient's disability by inquiring about what
activities are possible
 non respiratory factors, such as leg arthritis or
weakness

17.  Tachypnea
 Hyperpnea
 Hyperventilation
 Dyspnea on exertion
 Paroxysmal nocturnal dyspnea
 Orthopnea
 Platypnea

18.  DYSPNEA
 ACUTE – (PULMONARY EMBOLISM, PNEUMOTHORAX,
PULMONARY EDEMA) <30 days
 CHRONIC – (COPD, CHF) >30 days
 • TACHYPNEA – RR>20 BR/MIN ( PNEUMONIA)
 • BRADYPNEA - RR< 8 BR/MIN (DRUGS, AGONAL

19.  -EXERTIONAL DYSPNEA- due to exercise-
 ORTHOPNEA – lying flat and disappears setting
up (CHF, pregnancy, resp.muscle weakness)
 -PND – acute SOB almost always accompanied by
coughing and wheezing. usually occurs when a
person is already sleep in a reclining position
(HF -early night , ASTHMA-late night )
 -RESTING DYSPNEA-

20. Cardiac Pulmonary
Mixed
cardiac or
pulmonary
non-cardiac
non-
pulmonary

21. COPD Asthma
Restrictiv
e Lung
Disorders
Pulmonary Etiology

22. Hereditary
Lung
Disorders
Pneumonia Pneumo-
thorax

23. Congestive Heart
Failure (CHF)
Coronary Artery
Disease (CAD)
Recent or past
history of
Myocardial
Infarction (MI)
Cardiomyopathy

24. Valvular
dysfunction
Left
ventricular
hypertrophy
Pericarditis Arrhythmias

25. COPD with
pulmonary HTN
and/or cor
pulmonale
Deconditioni
ng
Chronic
pulmonary
emboli
Pleural
effusion

26. Metabolic
conditions
(e.g. acidosis)
Pain Trauma
Neuromuscular
disorders
Functional
(anxiety, panic,
hyperventilation)
Chemical
exposure

29. Causes of dyspnea as assessed by
Spirometry Echocardiography, & EKG in
129 SubjectsOnly 69% of
patients were
diagnosed by
these 3 tests
* Heart Disease
defined as AF, LV
systolic
dysfunction or
valve disease
Lung Disease
defined as
FEV1% < 70%
Obesity
defined as
BMI > 30 kg/m2
Pedersen et al., Int J Clin Pract, 2007, 61, 9, 1481–1491

30.  Respiratory system dyspnea
 Disease of the airways
 Disease of the chest wall
 Disease of the lung parenchyma

31.  Asthma
 COPD
 Acute bronchitis ( bronchial constriction )

32.  Kyphoscoliosis
 Weaken ventilatory muscle ( MG , GBS)
 Large pleural effusion
 Pneumo and heamothorax
 Traumatic chest injury

33.  Infections
 Occupational exposure
 Autoimmune disorder

34.  Diseases of the heart
 Disease of the mycardium (CAD)
 Non ischemic cardiomyopathies
 LV diastolic dysfunction
 Myocarditis
 Dysrhythmia
 Left atrial myxoma

35.  Pericarditis (constrictive )
 Cardiac tamponade

36.  Pulmonary thromboembolism disease
 Primary pulmonary disease ( PPH , pulmonary
vasculitis)

37.  Obesity
 Cardiovascular deconditioning
 Sensitivity to unpleasantness of hypercapnea
 impaired oxygen delivery (anemia, methe-
moglobinemia, cyanide ingestion, carbon
monoxide)
 Metabolic acidosis
 Panic disorder
 Neuromuscular disorder
 Toxin inhale and drugs

38. Speed of onset helps diagnosis;
Acute
 Foreign body
 Pneumothorax
 Acute asthma
 Pulmonary embolus
 Acute pulmonary edema

39. Subacute
 Asthma
 Parenchymal disease - eg. alveolitis, effusions,
pneumonia
Chronic
 COPD and chronic parenchymal diseases
 Non-respiratory causes – eg. Cardiac failure,
anemia

41. History of
present illness
Review of
systems
Past medical
history
Physical
examination
Interpretation
of findings
Testing Diagnosis

42. Patients perceptions:
Unsatisfied inspiration
Chest tightness
Sensation of feeling breathless
Cannot get enough air
Hunger for air
Incomplete exhalation
Associated underlying disease compliants

43. It should cover the following:
• Duration
• Onset (e.g., Abrupt, insidious)
• Positional changes
• Provoking or aggravating factors (eg, allergen
exposure, cold, exertion, supine position).
• Severity by assessing the activity level required to
cause dyspnea

44.  Past medical history should cover disorders known to
cause dyspnea, including asthma, COPD, and heart
disease.
 You should look for risk factors for the different
etiologies (next slide).
 Occupational exposures (eg, gases, smoke, asbestos)
should be investigated

45. In this step, you should look for symptoms of
possible causes.
For
example:
chest pain
or pressure
suggests
pulmonary
embolism
[PE],
myocardial
ischemia,
or
pneumonia
dependent
edema,
orthopnea,
and
paroxysmal
nocturnal
dyspnea
suggests
heart
failure
fever,
chills,
cough, and
sputum
production
suggests
pneumonia

46. •Smoking history
For cancer,
COPD, and
heart disease
•Family history, hypertension, and high cholesterol
levels
For coronary
artery disease
•Recent immobilization , trauma or surgery, recent
long-distance travel, prior or family history of clotting,
pregnancy, oral contraceptive use, calf pain, leg
swelling, and known deep venous thrombosis
For PE

47.  Vital signs: fever, tachycardia, and tachypnea.
 Temperature
 PR
 RR
 PO2 sat

48.  Wheezing?
 Asthma
 COPD
 Heart Failure
 Anaphylaxis

49.  Stridor? (Upper airway obstruction)
 Foreign body or tumor
 Acute epiglottitis
 Anaphylaxis
 Trauma, eg laryngeal fracture
 Crepitations?
 Heart failure
 Pneumonia
 Bronchiectasis
 Fibrosis

50.  Chest clear?
 Pulmonary embolism
 Hyperventilation
 Metabolic acidosis, eg diabetic ketoacidosis (DKA)
 Anemia
 Drugs, eg: salicylates
 Shock (may cause air hunger)
 Pneumocystis pneumonia
 Central causes
 Others
 Pneumothorax – pain, increased resonance
 Pleural effusion – 'stony dullness'

51.  Response to stress, anxiety
 Patient exhales CO2 faster than
metabolism produces it
 Blood vessels in brain constrict
 Anxiety, dizziness, lightheadedness
 Seizures, unconsciousness

52.  Chest pains, dyspnea
 Numbness, tingling of fingers, toes, area
around mouth, nose
 Carpopedal spasms of hands, feet

53.  Suspect in any child with
 Sudden onset of dyspnea
 Decreased LOC
 Suspect in any adult who develops
dyspnea or loses consciousness while
eating

54.  Associated with:
 Prolonged bed rest or immobilization
 Casts or orthopedic traction
 Pelvic or lower extremity surgery
 Phlebitis
 Use of BCPs

55.  Signs/Symptoms
 Dyspnea
 Chest pain
 Tachycardia
 Tachypnea
 Hemoptysis
Sudden Dyspnea + No Readily Identifiable Cause =
Pulmonary Embolism

56. Pulmonary embolism
Abrupt onset of
sharp chest pain,
tachypnea, and
tachycardia
Often risk factors
for pulmonary
embolism
• cancer,
• immobilization
• DVT
• pregnancy,
• use of oral
contraceptives
• recent surgery or trauma
CT angiography
V/Q scanning
pulmonary
arteriography

57. Anxiety disorder causing
hyperventilation
Situational
dyspnea often
accompanied by
psychomotor
agitation and
paresthesias in
the fingers or
around the mouth
Normal
examination
findings and
pulse oximetry
measurements
Diagnosis of
exclusion

58. Diagnosis Features
Acute asthma Wheeze with reduced peak flow rate
Previous similar episodes responding to bronchodilator therapy
Diurnal and seasonal variation in symptoms
Symptoms provoked by allergen exposure or exercise
Sleep disturbance by breathlessness and wheeze
Pulmonary
oedema Cardiac disease
Abnormal ECG
Bilateral interstitial or alveolar shadowing on chest x-ray

59. Pneumonia Fever
Productive cough
Pleuritic chest pain
Focal shadowing on
chest X-ray
Exacerbation of chronic
obstructive pulmonary
disease
Increase in sputum volume,
tenacity or purulence
Previous chronic bronchitis: sputum production
daily for 3 months of the year,
for 2 or more consecutive years
Wheeze with reduced peak
flow rate

60. Pulmonary
embolism
Pleuritic or non-pleuritic chest
pain
Haemoptysis
Risk factors for venous thromboembolism present (signs of
DVT commonly absent)
Pneumothorax
Sudden breathlessness in young
otherwise fit adult
Breathlessness following invasive procedure e.g
subclavian vein puncture
Pleuritic chest pain
Visceral pleural line on chest x-ray, with absent lung markings
between this line and the chest wall

61. Cardiac
tamponade Raised JVP
Pulsus paradoxus >
20mmHg
Enlarged cardiac silhouette on chest
X-ray
Known carcinoma of bronchus or
breast
Laryngeal
obstruction
History of smoke inhalation or the ingestion of
corrosives
Palatal or tongue oedema
Anaphylaxis

62. Tracheobronchial
obstruction
Stridor (inspiratory noise) or mnophonic
wheeze (expiratory 'squeak')
Known carcinoma of the bronchus
History of inhaled foreign body
PaCo2>5 kPa in the absence of chronic
obstructive pulmonary disease
Wheeze unresponsive to bronchodilators

63. Large pleural
effusion
Distinguished from pulmonary consolidation
on the chest x-ray by:
Shadowing higher laterally than medially
Shadowing does not conform to that of a
lobe or segment
No air bronchogram
Trachea and mediastinum pushed to
opposite side

64. Arterial blood gases and pH in breathlessness with a normal chest X-ray
Disorder PaO2 PaCO2 PHa
Acute asthma Normal/low Low High
Acute exacerbation of
COPD Usually low
May be
high
Normal or
low
Pulmonary embolism
Normal/low (without pre-existing
cardiopulmonary disease) Low High
Pre-radiological pneumonia Low Low High
Sepsis syndrome Normal/low Low Low
Metabolic acidosis Normal Low Low
Hyperventilation without
organic disease High/normal Low High

65.  Causes of dyspnea that can be managed
without chest radiography are few: ingestions
causing lactic acidosis, anemia,
methemoglobinemia, and carbon monoxide
poisoning.

66. Chest radiographs
Electrocardiograph
Screening
spirometry

67. Pulse
oximet
ry
CXR ECG ABG

68.  If no clear diagnosis obtained from chest x-ray
and ECG and patient is at moderate or high
risk of having PE, he should undergo
 CT angiography
 ventilation/perfusion scanning.
• Patients who are at low risk may have
 d-dimer testing (a normal d-dimer level effectively rules
out PE in a low-risk patient).

69. Chest x-ray
(CXR)
ECG
Cardiac
biomarkers
Brain natriuretic
peptide
D-Dimer ABG
Carbon dioxide
monitoring
Chest CT and
VQ scan
Peak flow and
pulmonary
function tests
(PFTs)
Negative
inspiratory force

70.  BNP or NT pro BNP
 Bronchopulmonary provocation test
 Chest HR CT
 Carboxyhemoglobin and methemoglobin level

71. Lung Disease
Airways disease
Interstitial Lung Disease
Neuromuscular Disease
Vocal Cord Dysfunction
PFTs
Chest Imaging (CXR, CT)
Methacholine ChallengeTesting
Heart Disease
Myocardial Disease (Systolic, Diastolic)
Valvular Heart Disease
Coronary Artery Disease
EKG
Echocardiography
BNP
PulmonaryVascular Disease
(Pulmonary Hypertension, PE)
Echocardiography, CTPA,V/Q
Metabolic Disease
Anemia
Thyroid Disease
CBC,TFTs
Deconditioning, Anxiety Exclusion

72.  The treatment of urgent or emergent causes of
dyspnea should aim to relieve the underlying
cause.
 Pending diagnosis, immediately provided
supplemental oxygen
 Opioid therapy, anxiolytics, and
corticosteroids can provide substantial relief
independent of the severity of hypoxemia
 Pulmonary rehabilitation, moderate to severe
COPD or interstitial pulmonary fibrosis

73.  Experimental interventions-e.g.， cold air on
the face， chest wall vibration， and inhaled
furosemide-aimed at modulating the afferent
information from receptors throughout the
respiratory system are being studied.
Morphine has been shown to reduce dyspnea
out of proportion to the change in ventilation in
laboratory models.

74.  CURRENT Medical Diagnosis and Treatment
2015
 Harrison's Principles of Internal Medicine, 19E
2-VOLUME SET (2015) [PDF] [UnitedVRG]
 Rosen Emergency Medicine -2014 .
 Guyton and Hall Textbook of Medical
Physiology
 Merck Manual of Diagnosis & Therapy
 http://en.wikipedia.org/wiki/Dyspnea#Treatment