dyspnea

Airway Alveolar ILD Vascular Pleural Left heart failure psychogenic neuromuscular systemic

Airway -Acute (asthma) -Chronic (COPD) Alveolar -Pneumonia Interstitial lung disease (ILD) Vascular -Pulmonary embolism Pleural -Pneumothorax Left heart failure -Ischemic -Hypertensive -Valvular Psychogenic -Anxiety Neuromuscular -Guillain Barre Syndrome Systemic

Systemic causes of dyspnea

Conditions Sepsis Metabolic acidosis Diabetic ketoacidosis Anemia Toxic ingestion CNS conditions There are a number of systemic and metabolic conditions that cause dyspnea for a variety of reasons. You should think of these when cardiac and pulmonary history and exams are normal. Sepsis causes dyspnea by increasing metabolic demands. Anemia causes dyspnea with exertion because of reduced oxygen-carrying capacity. Acidosis can cause tachypnea because the body's response is to hyperventilate to release carbon dioxide - you will learn more about this in physiology. Some CNS conditions and toxidromes can cause respiratory depression or abnormal breathing because of encephalopathy. Illness scripts / clinical presentations Depends on cause Likely absence of other respiratory symptoms e.g. cough, wheezing, chest pain Likely worse with exertion Physical examination findings relate to underlying condition. Laboratory findings relate to underlying condition. The main thing to remember is that if a patient has dyspnea without any particular lung or cardiac findings, you should consider a systemic cause and broaden your history taking and physical examination accordingly. You may shift away from a hypothesis-driven investigation (into lung or cardiac conditions) and toward a more "data first - hypotheses later" approach. Sepsis - fever, activity level, appetite, ill contacts, ill-appearing on exam, poor perfusion, hypotension Anemia - history of anemia, diet, fatigue, activity level, pallor on exam, tachycardia? CNS - history of neurologic symptoms, developmental milestones/regression, seizures, lethargy, neurological exam Toxin - history of ingestion, vital signs, pupil size, mental status Acidosis - due to other underlying problem

Dyspnea

Definition: "Subjective experience of breathing discomfort." Varies in intensity according to cause and setting May be described as Shortness of breath Increased effort to breathe Chest tightness Inability to get a good breath Air hunger How the patient describes their sensation can point you to various causes, which will be discussed with the individual illness scripts.

COPD

Pathophysiologic insult Airflow obstruction reduced forced expiratory flow increased residual volume Chronic hypoxemia pulmonary hypertension cor pulmonale Predisposing conditions Cigarette smoking Infections (cause COPD exacerbations) Occupational exposures Alpha-1-antitrypsin deficiency Cor pulmonale is right heart disease (dilitation and hypertrophy) that develops in response to pulmonary vasculature abnormalities. History - defining and discriminating features Chronic dyspnea Often described as increased effort of breathing or inability to get a good deep breath Usually progressive Cough common - typically with mucoid sputum Dyspnea worse with exertion May be worse with activities using arms May describe pursed lip breathing COPD refers to several diseases that cause airflow limitation that is not fully reversible. It includes emphysema and chronic bronchitis. Pursed lip breathing is a mechanism through which patients with COPD can relieve dyspnea. The slight obstruction to air flow at the mouth results in an increased in airway pressure, which helps to keep the airways open. Physical exam - defining and discriminating features Tachypnea Pursed lip breathing Barrel chest Accessory muscle use Lungs: decreased breath sounds; hyperresonance to percussion Cyanosis of lips and/or nail beds Clubbing of extremities Laboratory findings CXR - hyperinflation, enlarged A-P diameter PFT - increased residual volume, decreased VC and FEV ABG - hypoxemia, hypercarbia CBC - may show polycythemia (compensatory response) EKG/Echo - evidence of right heart enlargement It's important to note that the EKG and Echo findings of right heart enlargement are not specific to COPD. Any lung disease that increases pulmonary pressures can cause right heart disease.

Pneumonia

Pathophysiologic insult Bacterial infection of distal airways and alveoli with inflammation - Streptococcus, Staphylococcus, Hemophilus, Mycoplasma, others May be associated with pleural effusion Predisposing conditions Alcoholism Recent upper respiratory infection Immunosuppression Ill contacts History - defining and discriminating features Acute, gradually progressive May be mild or severe respiratory distress Distress worse with exertion Associated symptoms: fever, cough (often productive), decreased appetite and activity, pleuritic chest pain Physical exam - defining and distinguishing features Vital signs: fever, tachypnea, tachycardia May be well or ill appearing Accessory muscle use / retractions May see concomitant nasal congestion or otitis media Lungs: increased vocal fremitus, dullness to percussion, breath sounds decreased or bronchial, may hear crackles May see dehydration Laboratory findings Chest X-ray Consolidation or interstitial fluid CBC +/- elevated WBC with left shift (if bacterial) Tuberculin skin test Indicated if TB suspected Pulse oximetry May see increased concentration of deoxyhemoglobin Bacterial cultures of sputum or blood May help identify organism

Left Heart Failure

Pathophysiologic insult Elevated pulmonary capillary pressure transudation of fluid into interstitium and alveoli decreased lung compliance Predisposing conditions Valvular heart disease (e.g. rheumatic) Myocardial ischemic (CAD risk factors) Hypertension Family history of heart disease Chronic tachy- or brady-arrhythmias History - defining and discriminating features Dyspnea initially worse with exertion - with worsening failure, requires less exertion and may be at rest Fatigue Orthopnea Paroxysmal nocturnal dyspnea Nocturia Physical exam - defining and discriminating features Vital signs - may see HTN, tachypnea, tachycardia Decreased peripheral perfusion and/or edema May see JVD Lungs: crackles, +/- wheezing Heart: if enlarged, may see PMI displaced; +/- extra heart sounds (S3, S4). If valvular - murmur and/or thrill Abdomen: +/- hepatosplenomegaly Signs of right heart failure (JVD, edema, HSM) may be seen if left heart failure is severe/advanced. Laboratory findings CXR - evidence of pulmonary edema EKG - +/- evidence of previous ischemia or chamber enlargement Echo - gives evidence of cardiac function B-type natriuretic peptide - elevated BNP is a substance secreted from the heart in response to changes in pressure that occur when heart failure develops and worsens. The level of BNP in the blood increases when heart failure symptoms worsen and decreases when the heart failure condition is stable.

Psychogenic - Anxiety

Pathophysiologic insult Increased RR leads to hyperventilation Predisposing conditions Prior or family history of anxiety History - defining and discriminating features Dyspnea often occurs at rest Fairly acute onset; often recurrent May be relieved with breathing in paper bag Physical exam - typically normal Laboratory findings - none specific For the next few conditions, I will go through them quickly because you just need to be aware that conditions other than pulmonary and cardiac can cause dyspnea. Being aware of this will help you when pulmonary and cardiac histories and exams are negative. Anxiety is one of these. It's important to consider anxiety, especially if dyspnea acute or recurrent, but be careful not to prematurely close in on this diagnosis without strongly considering more serious causes of dyspnea. Even patients who have had a history of anxiety can present with heart failure or an acute pulmonary cause of dyspnea

Asthma

Pathophysiologic insult Increased bronchial reactivity to triggers causes bronchoconstriction and obstruction with air trapping Inflammation of the airway Predisposing conditions Prior or family history of asthma or other atopic disease History - defining and discriminating features Acute, gradual onset, recurrent Chest tightness, difficulty getting a good breath May be associated with trigger exposures e.g. change in weather, outdoor allergens, upper respiratory infections Worse with exertion Better with bronchodilators Associated symptoms: fever if associated with infection, cough Asthma is a recurrent process. An exacerbation may develop acutely over a couple of days. Physical exam - defining and distinguishing features Vital signs - tachypnea May be well or ill appearing depending on degree of bronchoconstriction Accessory muscle use / retractions Lungs: decreased air movement, diffuse expiratory wheezes +/- hyperresonance to percussion Laboratory findings CXR - hyperinflation PFT - decreased FEV1 (improves after bronchodilator

Interstitial Lung Dx (ILD)

Pathophysiologic insult Inflammation and fibrosis Granulomatous Predisposing conditions Occupational and environmental exposures (numerous) Underlying connective tissue disease e.g. sarcoid, SLE Family history of lung fibrosis Cigarette smoking History - defining and discriminating features May be acute or chronic based on cause Dyspnea worse with exertion Fatigue Nonproductive cough Other features if associated with underlying connective tissue disease Rash Weakness ILD are characterized by diffuse involvement of lung parenchyma and can either be a primary problem or associated with some kind of connective tissue disease. Causes include idiopathic pulmonary fibrosis, sarcoidosis, numerous others Physical exam - defining and discriminating features Tachypnea Lungs: may hear diffuse fine crackles throughout If advanced - signs of right heart failure (cor pulmonale); clubbing of extremities Laboratory findings CXR with interstitial pattern Other labs +/- based on underlying disease

Pneumothorax Pneumothorax is an accumulation of air between the parietal and visceral pleurae

Pathophysiologic insult Trapped air in the pleural space puts pressure on lung, leading to lung collapse Tension pneumothorax - pressures high enough to cause circulatory impairment Predisposing Conditions Trauma Spontaneous - young healthy adults, thin body habitus Chronic obstructive pulmonary disease History - discriminating and defining features Acute with sudden onset Sharp, pleuritic unilateral chest pain Feeling of anxiety Physical examination - discriminating and defining features Vital signs - +/- elevated RR and HR Neck - tracheal deviation or JVD if tension; possible subcutaneous emphysema Heart - possible distal heart sounds Lungs - decreased vocal fremitus, hyperresonnance to perfusion, decreased BS Extremities - possible decreased perfusion Typical laboratory findings Chest X-ray Air in the pleural space and possibly mediastinum Pulse oximetry May show increased concentration of deoxyhemoglobin Arterial blood gas If tension, may see decreased paO2 and increased paCO2

Pulmonary Embolism

Pathophysiologic insult Venous thrombi dislodge from distal site and travel to pulmonary bed Arterial occlusion Alveolar collapse Predisposing conditions Immobilization Smoking Medications e.g. OCP Malignancy History - discriminating and defining features Typically acute, sudden onset Acute pleuritic chest pain Cough Hemoptysis +/- Leg pain or swelling Feeling of anxiety Physical examination - discriminating and defining features Vital signs - elevated RR and/or HR Heart - typically normal unless underlying disease Lungs - +/- decreased BS or pleural friction rub Abdomen - typically normal unless underlying disease Extremities - +/- leg edema and/or tenderness, especially calf and popliteal fossa Laboratory findings D-dimer Elevated Chest CT with contrast Identifies even small peripheral emboli Ventilation-perfusion scan Identifies absent or decreased blood flow Chest X-ray May be normal or show atelectasis

Neuromuscular -Guillain Barre

Pathophysiologic insult Weakness of accessory muscles of respiration Diminished vital capacity Predisposing conditions Recent infections (e.g. gastroenteritis) Family history of weakness History - defining and discriminating features Muscular weakness before dyspnea There are a number of neuromuscular conditions that lead to such profound weakness that the accessory muscles of respiration are involved. This can lead to dyspnea and respiratory failure, sometimes ultimately requiring intubation and mechanical ventilation. But these conditions will not present with dyspnea alone. Weakness will be evident on history and exam. Physical exam- defining and discriminating features Muscle weakness Shallow breathing Areflexia Laboratory findings CSF - Cytoalbuminologic dissociation (elevated protein with normal WBC) EMG/NCV - show demyelination

Heart Failure

Right vs Left: Right - often secondary to pulmonary disease (cor pulmonale) Left - valvular, hypertensive, ischemic High vs Low output: High output - secondary to systemic or metabolic disease e.g. anemia, hyperthyroidism, sepsis Low output - decreased CO (secondary to changes in SV or HR) Heart failure can be caused by a number of conditions - it is not sufficient to simply diagnose someone with heart failure. It is similar to anemia - once you have determined that it exists, you must determine the cause. There are a couple of ways to look at heart failure. Dyspnea associated with heart failure is typically related to pulmonary edema because of elevated pulmonary capillary pressure (back up of pressure from a failing left heart). In this lecture on dyspnea therefore, we will focus on left heart failure. A simple way to categorize left heart failure is valvular, hypertensive, ischemic, although there are other causes. The symptoms of right heart failure are somewhat different - peripheral edema, HSM, JVD We will also focus on low output failure Valvular heart disease can cause heart failure depending on which valve is involved. If a patient has aortic stenosis, the heart is going to increase its work trying to eject blood through the stenotic aortic valve. In mitral stenosis, left ventricular filling is diminished, which can cause diastolic dysfunction. Hypertension causes heart failure because of increased afterload. Ischemia leads to decreased contractility.