• They are of value when infective etiology such as pneumonia, lung abscess is suspected. In an acutely dyspneic patient the value of sputum examination depends on the production of uncontaminated sputum sample.
Pulmonary Function Tests
• Spirometry—With increasing airflow limitation, FEV1 falls proportionately more than the FVC, so that the FEV1 / FVC ratio is reduced.
Arterial Blood Gases (ABG)
• Useful in assessing the type, degree of respiratory failure, and measuring the overall acid-base status
• An increased pH with decreased pCO2 indicates acute respiratory alkalosis, whereas both decreased pH and bicarbonates indicate metabolic acidosis, such as due to DKA.
However, normal levels of oxygenation are not useful to exclude respiratory or cardiac diseases causing acute dyspnea.
Bronchoscopy
• It should be performed if aspiration of foreign body is suspected; the procedure can be both diagnostic and therapeutic.
• It also allows collection of bronchial secretions for bacteriological/cytological examination.
D-dimer
• This is useful in determining risk for DVT or PE.
HRCT of Thorax
• Spiral CT scanning of the chest with iodinated contrast is gradually replacing ventilation-perfusion lung scanning as the screening procedure of choice for the diagnosis of pulmonary embolic disease
• V/Q scans are recommended only if spiral CT is not available
• MR angiograms are recommended as a first line investigation only if spiral CT is contraindicated.
V/Q scan
• V/Q scan should be used in cases where results of HRCT are inconclusive, which may necessitate the use of pulmonary angiography.
BNP (Brain or B-type Natriuretic Peptide)
• This test is useful to evaluate for the presence of CHF in patients with dyspnea. A low value (<80 pg/ml) has a high (99%) negative predictive value that helps to rule out CHF;
a high value (>100 pg/ml) is nonspecific, but is about 90% sensitive for CHF.
Echocardiography
• This procedure is indicated if CHF, valvular heart disease, or pericardial effusion is suspected. It also helps to identify an embolus in suspected PE. Pulmonary artery pressure can also be estimated to rule out pulmonary hypertension causing dyspnea.
Drug Screen
• Serum levels of salicylates and other drugs (e.g. Amiodarone) suspected to be responsible.
Dyspnea—Acute 111
CLINICAL NOTES
• In an acutely dyspneic patient it is important to ensure that the Airway, Breathing, Circulation (ABC) are attended to before continuing with the diagnostic process. Life-threatening problems must be excluded during initial examination (Table 16.1). The following checklist of questions is useful in practice:
Table 16.1: Life-threatening causes of dyspnea
• Myocardial infarction
• Ventricular tachycardia
• Status asthmaticus
• Pulmonary embolism
• Tension pneumothorax
• Anaphylactic laryngeal edema
• Airway obstruction
• Diabetic ketoacidosis
• Guillain-Barré syndrome
• Carbon monoxide poisoning
• Salicylate poisoning
Is it dyspnea or a condition stimulating it?
Is it due to cardiac dysfunction?
Is it due to pulmonary dysfunction?
If cardiac, what is the grade of dyspnea?
Is there PND or orthopnea?
Is the patient receiving drugs; if so what is the response?
What are the associated symptoms?
• Once an emergent situation has been excluded, reassess the patient’s airways, mental status, ability to speak, and breathing effort, and question the patient (or a family member) about duration of the dyspnea, any underlying cardiac or pulmonary disease, medication use, cough, fever, chest pain, and trauma
• Dyspnea should be differentiated from tachypnea and hyperventilation which refer to respiratory variations regardless of the patient’s subjective sensations. Tachypnea is
the objective finding of a rapid respiratory rate and may or may not be associated with the feeling of not being able to breathe properly; tachypnea may be necessary for a sufficient gas-exchange of the body, for example after exercise, in which case it is not hyperventilation. Hyperventilation (or overbreathing) is an increase in the respiratory rate above normal — a state of breathing faster and/or deeper than necessary, thereby reducing the carbon dioxide concentration of the blood below normal. These conditions may not always be associated with dyspnea. Orthopnea is the sensation of breathlessness in the recumbent position, relieved by sitting or standing. Two uncommon types of breathlessness are trepopnea and platypnea. Trepopnea is dyspnea that occurs in one lateral decubitus position as opposed to the other (e.g. in patients with unilateral lobectomy, pneumonectomy). Platypnea refers to breathlessness that occurs in the upright position and is relieved with recumbency (e.g. hepatopulmonary syndrome, cardiac shunt — Tetralogies of Fallot)
• Although the diagnosis of hyperventilation syndrome is suggested by associated symptoms of panic and anxiety, or frequent sighing, it is wise to exclude cardiopulmo-nary diagnosis before arriving at this diagnosis
• Differentiation between bronchial asthma and cardiac asthma is critical (Table 16.2).
However, both cardiac and pulmonary disease and/or disorders of different systems may coexist in the same patient; e.g. LVF and COPD, pneumonitis and ARDS, respiratory muscle paralysis and aspiration pneumonia
Diagnosis: A Symptom-based Approach in Internal Medicine 112
Table 16.2: Clinical differentiation between cardiac and bronchial asthma
Points Cardiac asthma Bronchial asthma A g e Usually elderly Any age
or older
Past history CAD, hypertension Previous attacks valvular disease of asthma, atopy Family history Usually non- Generally
contributing positive Precipitating Exertion, Exposure to
factors infraction allergens
Symptoms Cough, frothy Cough, thick expectoration stick sputum;
prominent; wheezing
wheezing not marked marked
Pulse Rapid; pulses Rapid; may alternans may be be feeble in
present severe/
prolonged asthma; no pulses alternans Auscultation Triple rhythm, Normal heart
murmurs, sounds
pericardial rub
Breath sounds Expiration not Expiration prolonged, basal markedly crepts prominent prolonged;
wheezing all over chest
• Intensity of wheezing is unreliable. Some patients with asthma do not wheeze and some who wheeze do not have asthma
• The presence of orthopnea or paroxysmal nocturnal dyspnea (PND) is more suggestive of cardiac failure than of lung disease
• Deep ‘sighing’ respiration (Kussmaul respiration, air hunger) of acidosis, usually seen in diabetic and uremic patients, or Cheyne-Stokes respiration (periodic breathing), usually seen in cerebrovascular disease, or poisoning, should not be mistaken for acute dyspnea
• Subcutaneous emphysema should raise suspicion of associated pneumothorax.
• A review of medications may provide useful clues to the possible cause of the dyspnea,
especially in the evaluation of a new patient.
For example, use of an inhaler would point to a possible history of asthma or COPD. If patient is taking furosemide he may have a history of CHF
• Angioedema, characterized by facial, extremity, and airway edema, may cause difficulty breathing, and is a possible adverse effect seen in patients who begin taking an ACE inhibitor such as captopril
• Cardiac tamponade related to trauma or HIV is more common in young adults, whereas tamponade due to malignancy and/or renal failure occurs more frequently in elderly individuals
• A diagnostic strategy that combines a high degree of clinical suspicion; careful evaluation of historical and clinical findings (e.g. dyspnea, pleuritic chest pain, tachypnea, and tachycardia); risk factors for venous thromboembolism (e.g. recent surgery or immobilization, stroke, CHF, cancer, fracture of the pelvis, femur or tibia, obesity, pregnancy or recent delivery; estrogen therapy; inflammatory bowel disease, and various genetic or acquired thrombophilia);
and corroborative findings from noninvasive diagnostic techniques (e.g. D-dimer, HTCT of lungs) can improve diagnostic accuracy of PE. However, many cases of PE are indeed clinically silent
• Physical examination— Common physical findings are listed in Table 16.3.
RED FLAGS
• Respiratory rate over 30/mit, pulse rate over 120/mit, and pulsus paradoxus greater than 18 mm Hg indicate a dangerously severe episode of dyspnea
• Dyspnea at rest, orthopnea, sweating, and difficulty speaking in sentences, use of accessory muscles of respiration, decreased
Dyspnea—Acute 113
Table 16.3: Physical examination findings in the diagnosis of acute dyspnea in adults and children
Findings Possible diagnosis
Cyanosis, wheezing, pulsus paradoxus, Acute asthma, COPD accessory muscle use exacerbation Wheezing, clubbing, barrel chest, COPD exacerbation decreased breath sounds
Fever, localized crepts, increased Pneumonia fremitus
Edema, JVP, S3 or S4, gallop rhythm, CHF, LVF hepatojugular reflux, murmurs,
basal crepts, hypertension
Beck triad-distended JVP, Cardiac tamponade hypotension, muffled heart sounds
Pulsus paradoxus, pericardial rub Cardiac tamponade, severe asthma
Chest pain, localized crepts, friction DVT, pulmonary embolism rub, edema feet, calf swelling,
recent child delivery
Absent breath sounds, hyper Pneumothorax resonance
Trauma, surgery, shock ARDS
Inspiratory stridor, rhonchi, Acute
laryngo-retractions tracheobronchitis (Croup)
Stridor, drooling, fever Epiglottitis
Stridor, wheezing, persistent Foreign body aspiration pneumonia
Wheezing, flaring, intercostal Bronchiolitis retractions, apnea
Sighing Acidosis, hyperventilation
mental status or consciousness indicate a life-threatening situation and constitute an indication for urgent intubation
• In a case of asthma, absence of wheezing (silent chest) or decreased wheezing can indicate worsening obstruction
• No single noninvasive test or clinical evaluation can definitively point to a diagnosis of PE, and this frequently missed diagnosis may have fatal consequences
• Cardiac tamponade is a medical emergency.
Early diagnosis and treatment are crucial to reduce morbidity and mortality. Untreated, it is rapidly and universally fatal.
REFERENCES
1. Martinez-Moragon E, et al. Asthma patients’
perception of dyspnea during acute bronchocon-striction. Aech Bronconeumol 2003;39(2):67-73.[ PMID: 12586046: Abstract].
2. Bijl-Hofland ID, et al. Relation of the perception of airway obstruction to the severity of asthma.
Thorax. 1999;54(1):15-19. [PMID: 10343625:
Abstract].
3. Dyspnea. Mechanisms, Assessment, and Manage-ment: A Consensus statement. American Thoracic Society. (1999). Am J Respir Crit Care Med; 159, 321-40. [PMID: 9872857: Free full text]
SYNOPSIS
Breathlessness that persists for more than a month may be termed as chronic dyspnea. This symptom is present in many different illnesses.
Fortunately, only a few disorders are seen in practice; therefore, a logical and time saving first step is to do a rapid assessment of the patient’s general level of distress and vital signs to exclude the causes for acute dyspnea.* The next step is to evaluate the patient for the possible causes of chronic dyspnea.
A patient with chronic dyspnea may present with any of the following four grades based on New York Heart Association classification:
• Class I – Disease present but no dyspnea or dyspnea only on heavy exertion
• Class II – Dyspnea on moderate exertion
• Class III – Dyspnea on minimal exertion
• Class IV – Dyspnea at rest.
It is more useful, however, to determine the amount of exertion that actually causes dyspnea, i.e. the distance walked, or the number of steps climbed to assess the functional
capacity. Although there are many tests or protocols developed to assess individual’s functional capacity, they are prone for subjective errors by either overestimating or underesti-mating their true functional capacity. Therefore the American Thoracic Society (ATS) has issued standardized guidelines for the 6-minute walk test (6MWT: vide infra ↓↓), which is safe, easier to administer, better tolerated, and better reflects functional cardiopulmonary status and activities of daily living.1-5
DIFFERENTIAL DIAGNOSIS Common
• Asthma
• COPD (chronic bronchitis, emphysema)
• CHF
• IHD (angina: stable, unstable)
• Postnasal drip syndrome
• GERD
• Morbid obesity (rapid weight gain)
• Sedentary lifestyle (physical deconditio-ning)
• Psychogenic (GAD, PTSD, panic disorder).
* Ref: Chapter 16: Dyspnea—Acute.