05/02/2023 Lailmaah habibi

الرحیم الرحمن الله بسم

Dyspnea defination 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

Physiology of Breathing

Pulmonary volumes

• 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

Pulmonary capacities

• 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

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

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

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.

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

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

Sensory Afferents Chemoreceptors Mechanoreceptors Metaboreceptors

Dyspnea likely results from the complex interaction between:

chemoreceptor stimulation (Afferent)

mechanical breathing abnormalities (Efferent) perception of those

two by the CNS

Contribution of Emotional or Affective Factors to Dyspnea

Acute anxiety or fear may increase the severity of dyspnea either by altering the inter pretation of sensory data

ASSESSING DYSPNEAQuality of Sensation ;

Sensory Intensity

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.

An alternative approach is to gain a sense of the patient's dis ability by inquiring about what activities are possible

non respiratory factors, such as leg arthritis or weakness

The following terms may be used in the assessment of the dyspneic patient: Tachypnea Hyperpnea Hyperventilation Dyspnea on exertion Paroxysmal nocturnal dyspnea Orthopnea Platypnea

THE PNEA’S

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

Stages of Cardiac dyspnea -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-

Four general category causes

Cardiac Pulmonary

Mixed cardiac or pulmonary

non-cardiac non-pulmonary

COPD AsthmaRestrictiv

e Lung Disorders

Pulmonary Etiology

Hereditary Lung

DisordersPneumoni

aPneumo-thorax

Congestive Heart Failure

(CHF)

Coronary Artery

Disease (CAD)

Recent or past history

of Myocardial Infarction

(MI)

Cardiomyopathy

Cardiac Etiology

Valvular dysfuncti

on

Left ventricular hypertrop

hy

Pericarditis

Arrhythmias

COPD with pulmonary HTN and/or

cor pulmonale

Deconditioning

Chronic pulmonary

emboliPleural effusion

Mixed Cardiac/Pulmonary Etiology

Metabolic conditions

(e.g. acidosis)Pain Trauma

Noncardiac or Nonpulmonary Etiology

Neuromuscular disorders

Functional (anxiety, panic,

hyperventilation)Chemical exposure

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 systolicdysfunction 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

DIFFERENTIAL DIAGNOSIS Respiratory system dyspnea Disease of the airways Disease of the chest wall Disease of the lung parenchyma

Disease of airways Asthma COPD Acute bronchitis ( bronchial constriction )

Disease of chest wall Kyphoscoliosis Weaken ventilatory muscle ( MG , GBS) Large pleural effusion Pneumo and heamothorax Traumatic chest injury

Disease of lung parenchyma

Infections Occupational exposure Autoimmune disorder

Cardiovascular system dyspnea

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

Disease of the pericardium

Pericarditis (constrictive ) Cardiac tamponade

Disease of pulmonary vasculature

Pulmonary thromboembolism disease Primary pulmonary disease ( PPH ,

pulmonary vasculitis)

Dyspnea vs. normal cardiovascular and respiratory

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

Speed of onset helps diagnosis;

Acute Foreign body Pneumothorax Acute asthma Pulmonary embolus Acute pulmonary edema

Subacute Asthma Parenchymal disease - eg. alveolitis,

effusions, pneumonia

Chronic COPD and chronic parenchymal diseases Non-respiratory causes – eg. Cardiac

failure, anemia

Steps to reach to diagnosis

History of present illness

Review of systems Past medical history

Physical examination Interpretation of findings

Testing Diagnosis

Chief compliantPatients perceptions: Unsatisfied inspiration Chest tightness Sensation of feeling breathless Cannot get enough air Hunger for air Incomplete exhalationAssociated underlying disease compliants

History of present illness

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

Past medical history 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

Review of systems

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 pneumoni

a

Risk factors for the different etiologies

•Smoking historyFor 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 thrombosisFor PE

Physical examination Vital signs: fever, tachycardia, and

tachypnea. Temperature PR RR PO2 sat

Breathlessness : emergency presentations

Wheezing? Asthma COPD Heart Failure Anaphylaxis

Stridor? (Upper airway obstruction) Foreign body or tumor Acute epiglottitis Anaphylaxis Trauma, eg laryngeal fracture

Crepitations? Heart failure Pneumonia Bronchiectasis Fibrosis

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'

Hyperventilation Syndrome

Response to stress, anxiety Patient exhales CO2 faster than

metabolism produces it Blood vessels in brain constrict Anxiety, dizziness, lightheadedness Seizures, unconsciousness

Hyperventilation Syndrome

Chest pains, dyspnea Numbness, tingling of fingers, toes,

area around mouth, nose Carpopedal spasms of hands, feet

Foreign Body Obstruction Suspect in any child with

Sudden onset of dyspnea Decreased LOC

Suspect in any adult who develops dyspnea or loses consciousness while eating

Pulmonary Embolism Associated with:

Prolonged bed rest or immobilization Casts or orthopedic traction Pelvic or lower extremity surgery Phlebitis Use of BCPs

Pulmonary Embolism Signs/Symptoms

Dyspnea Chest pain Tachycardia Tachypnea Hemoptysis

Sudden Dyspnea + No Readily Identifiable Cause = Pulmonary Embolism

The probable Differential diagnosis of dyspnea with acute onset

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

The probable Differential diagnosis of dyspnea with acute onset

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

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

Pneumonia Fever

Productive cough

Pleuritic chest painFocal shadowing on chest X-ray

Exacerbation of chronic obstructive pulmonary disease

Increase in sputum volume, tenacity or purulencePrevious chronic bronchitis: sputum production daily for 3 months of the year, for 2 or more consecutive yearsWheeze with reduced peak flow rate

Pulmonary embolism

Pleuritic or non-pleuritic chest pain

Haemoptysis

Risk factors for venous thromboembolism present (signs of DVT commonly absent)

PneumothoraxSudden 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

Cardiac tamponade Raised JVP

Pulsus paradoxus > 20mmHgEnlarged cardiac silhouette on chest X-rayKnown carcinoma of bronchus or breast

Laryngeal obstruction

History of smoke inhalation or the ingestion of corrosives

Palatal or tongue oedemaAnaphylaxis

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

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

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 embolismNormal/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

Diagnostic studies Causes of dyspnea that can be managed

without chest radiography are few: ingestions causing lactic acidosis, anemia, methemoglobinemia, and carbon monoxide poisoning.

Chest radiographs

Electrocardiograph

Screening spirometry

Diagnosis

Testing

Pulse oxime

try

CXR ECG ABG

Extra Testing 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).

Ancillary studies list

Chest x-ray (CXR) ECG Cardiac

biomarkers

Brain natriuretic

peptideD-

Dimer  ABGCarbon dioxide

monitoring

Chest CT and VQ scan

Peak flow and pulmonary

function tests (PFTs)

Negative inspiratory

force

BNP or NT pro BNP Bronchopulmonary provocation test Chest HR CT Carboxyhemoglobin and methemoglobin

level

Basic Workup of Exertional Dyspnea

Lung Disease Airways disease Interstitial Lung DiseaseNeuromuscular Disease Vocal Cord Dysfunction

PFTsChest Imaging (CXR, CT)Methacholine Challenge Testing

Heart DiseaseMyocardial Disease (Systolic, Diastolic)Valvular Heart DiseaseCoronary Artery Disease

EKGEchocardiographyBNP

Pulmonary Vascular Disease (Pulmonary Hypertension, PE) Echocardiography, CTPA,

V/QMetabolic Disease Anemia Thyroid Disease

CBC, TFTs

Deconditioning, Anxiety Exclusion

treatment 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

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.

Resources 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

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