Pulmonary Disease: Signs, Symptoms, and Dyspnea

• Pulmonary ailments classify as acute/chronic, obstructive/restrictive, infectious/non-infectious, and malignant/benign
• Lung disorders signs/symptoms are common, associated with primary lung issues and other organ ailments, especially the heart

Clinical Manifestations of Pulmonary Alterations

Signs and Symptoms of Pulmonary Disease

• Pulmonary conditions show multiple signs and symptoms; their specific features help pinpoint the underlying disorder
• Additional indicators include unusual sputum, hemoptysis, abnormal breathing, cyanosis, nail clubbing and chest pain

Dyspnea

• Dyspnea is a subjective experience of breathing discomfort and a common symptom of pulmonary disease
• Dyspnea is often described as breathlessness, air hunger, shortness of breath, or labored breathing
• Individuals often become preoccupied with breathing when experiencing dyspnea
• Dyspnea can stem from acute pain, heart issues, trauma, and anxiety
• Dyspnea arises from the interaction of physiological, psychological, social and environmental factors
• Stimulation of receptors, including afferent receptors (brain/brainstem), mechanoreceptors (chest wall/upper airway), and chemoreceptors contributes to dyspnea
• These receptors communicate with the CNS respiratory control, sending signals to modulate breathing
• Neuro-mechanical dissociation between the neural drive to breathe and the respiratory's ability to respond mechanically often exists
• Damage to lung parenchyma, ventilation disturbances, increased need to ventilate, altered gas exchange or reduced compliance/ventilatory capacity can cause dyspnea
• Dyspnea can occur transiently or chronically, and its magnitude may not correlate with the disease's severity
• Dyspnea on exertion (DOE) often initially presents during exercise is common in individuals with lung disorders
• Orthopnea is dyspnea when lying down, increasing intrathoracic/intraabdominal pressure, often relieved by standing
• Paroxysmal nocturnal dyspnea (PND) occurs when individuals wake at night with air hunger, requiring sitting/standing to relieve them
• Severe signs include nasal flaring and use of accessory muscles
• Retractions can be observed in children and individuals with poorly developed thoracic musculature
• Quantifying dyspnea involves rating subjective complaints using a scale
• Dyspnea may be unnoticed in mechanically ventilated individuals and often is accompanied by pain/anxiety

Cough

• Cough is a protective reflex clearing airways via explosive expiration
• Inhaled particles, mucus, inflammation, or foreign bodies trigger the cough reflex through irritant receptors in the airway epithelium
• Few receptors exist in the most distal bronchi/alveoli, allowing mucus to accumulate without initiating the cough reflex
• The cough reflex includes inspiration, glottis/vocal cord closure, expiratory muscle contraction, and glottis reopening
• Physiological events cause forceful air movement/expiration, removing offending substances
• Cough effectiveness relies on respiratory muscle strength and inspiration depth, which can lead to pneumonia
• Acute cough is cough that resolves within 2-3 weeks or with treatment of the underlying condition
• Acute cough causes include upper/lower respiratory infections, allergic rhinitis, bronchitis, pneumonia, heart failure, pulmonary embolus or aspiration
• Chronic cough lasts beyond eight weeks
• Postnasal drainage, asthma, bronchitis/bronchiectasis, and gastroesophageal reflux are common non-irritant causes
• ACE inhibitors can cause chronic cough due to decreased bradykinin/substance P breakdown, stimulating the cough reflex
• Chronic bronchitis is the most common cause of chronic cough in smokers/toxin inhalers

Abnormal Sputum

• Sputum changes in amount, color, consistency offer info about the cause/progression of disease and treatment effectiveness
• Expectorated sputum can be clear, foamy, bloody or purulent (yellow, green or creamy)
• Clinicians use microscopic/gross sputum appearances to identify cellular debris/microorganisms, aiding diagnosis/treatment
• Hemoptysis is coughing up bloody sputum from the tracheobronchial branches and has alkaline pH
• Hematemesis is vomiting blood that is dark, acidic and mixed with food particles
• Hemoptysis suggests lung cancer or lung infection; PE, cancer, can be other possible causes
• Bleeding amount/duration offer clues, with chest imaging/bronchoscopy pinpointing bleeding location

Abnormal Breathing Patterns

• Normal breathing (eupnea) is involuntary, rhythmic and effortless with resting rate of 8-16 breaths/min and tidal volume (400-800mL)
• Sighs are voluntary, contribute to normal function, occur 1.5-2x normal, and happen ~10-12 times per hour
• Anxiety causes frequent, sighing inspirations/respirations
• Rate, depth, regularity and effort alter based on physiological/pathophysiologic conditions, adjusting automatically to reduce respiratory muscle work
• Strenuous exercise/metabolic acidosis causes Kussmaul respiration (hyperpnea): slightly increased rate and large tidal volumes
• Labored breathing occurs when respiratory effort increases, especially with obstructed airways
• Large airway obstruction has a slow rate (bradypnea), large tidal volume, increased effort, prolonged inspiration/expiration, and stridor/wheezing
• Small airway obstruction has rapid rate, small tidal volume, increased effort, prolonged expiration, and wheezing
• Restricted breathing commonly arises from disorders like pulmonary fibrosis that stiffen lungs/chest wall and lowers compliance, resulting in small volumes and tachypnea
• Shock and severe cerebral hypoxia contribute to gasping respirations, quick inspirations with an expiratory pause
• Cheyne-Stokes respirations alternate between deep/shallow breathing and apnea
• Apnea lasts 15+ seconds, followed by increasing ventilations until a peak occurs then tidal volume reduces to apnea
• Conditions reducing brainstem blood flow cause Cheyne-Stokes respirations slowing impulses to respiratory centers
• Neurologic impairment above the brainstem can be a contributing factor

Hypoventilation and Hyperventilation

• Hypoventilation is inadequate alveolar breathing relative to metabolic needs, reduces minute breathing, and results from either an alteration in the drive to breathe or the ability to do so
• While alveolar breathing is normal, carbon dioxide (CO2) is eliminated at the same rate it's produced, keeping arterial (PaCO2)/alveolar (PACO2) carbon dioxide pressure at normal levels
• With hypoventilation, carbon dioxide removal lags, increasing PaCO2 (hypercapnia) resulting in increased hydrogen ion concentration
• The increase of hydrogen ion concentration leads to a pH lower than 7.35 (respiratory acidosis) which impacts tissue function/ability
• Hypoventilation might be overlooked until severe, measurement of PaCO2 blood analysis or CO2 volume, reveals hypoventilation
• Leads to secondary hypoxemia, somnolence and disorientation
• Hyperventilation is alveolar breathing exceeding metabolic requirements, thus removing carbon dioxide faster than production/metabolism
• This results in reduced PaCO2 (hypocapnia) dropping hydrogen blood ions, leading to pH above 7.45 (respiratory alkalosis)
• Hyperventilation commonly occurs with severe anxiety, acute head injury, and pain
• Like hypoventilation, hyperventilation via arterial blood gas analysis

Cyanosis

• Cyanosis is the bluish discoloration of skin/mucous as result of increasing amounts of desaturated or reduced hemoglobin (bluish)
• Peripheral cyanosis from poor circulation, heart disease, vasoconstriction, or cold, best seen in nail beds
• Central cyanosis results from decreased arterial oxygenation (low PaO2) from lung/CNS disorders, best assessed in buccal membranes/lips
• Lack of cyanosis doesn't always mean normal oxygenation, cyanosis is an insensitive indicator of respiratory failure
• Severe anemia, carbon monoxide poisoning can cause inadequate oxygenation without cyanosis
• Individuals with polycythemia may show cyanosis despite adequate oxygenation
• Interpret cyanosis in relation to pathophysiology; if cyanosis is suspected blood gas analysis should be done

Clubbing

• Clubbing is the selective enlargement of the end of a digit (finger/toe), graded to extent of nail bed changes, usually slow and painless process
• Lung cancer is the most common cause
• Chronic hypoxemia-related diseases like bronchiectasis, cystic fibrosis, lung abscess, and congenital heart disease are associated with clubbing
• Gastrointestinal, hepatobiliary, and endocrine disorders can also be associated with clubbing
• Platelet clumps in lung cancer release platelet-derived growth factor (PDGF), causing periosteal changes near the nail bed
• In chronic hypoxemia, reduced oxygen triggers the release of vascular endothelial growth factor, promoting connective tissue proliferation, clubbing is rarely reversible

Pain

• Pulmonary pain sources are the pleurae, airways or chest wall
• Pleurisy (pleuritis) cause sharp/stabbing pain (pleurodynia) when pleura stretches during inspiration, a pleural friction rub can be heard during inspiration
• Laughing/coughing worsens pleural pain
• Tracheitis/tracheobronchitis cause chest pain when coughing
• Pulmonary hypertension can is often mistaken for cardiac pain
• Chest wall pain is rib/muscle pain due to coughing, fractures, or thoracic surgery
• Inflammation of the costochondral junction (costochondritis) causes chest pain
• Chest wall pain can be felt by pressing on the sternum or ribs

Conditions Caused by Pulmonary Disease or Injury: Hypercapnia

• Hypercapnia (increased PaCO2) results from alveolar hypoventilation
• Carbon dioxide easily enters the alveolar space, but normal alveolar ventilation is needed to maintain the correct PaCO2
• Minute breathing (rate x tidal volume) impacts alveolar pressure
• Respiratory rate is measured, bedside tidal volume not assessed so hypoventilation might be missed
• Blood gas analysis/capnography is important for assessing severity and resultant respiratory acidosis
• Hypercapnia causes are usually a decreased drive to breathe or inadequate response to ventilation
• Depression of the respiratory center by drugs, diseases of the medulla, spinal abnormalities, neuromuscular junction diseases, thoracic cage abnormalities, airway obstruction are causes
• Hypercapnia/ acidosis can cause dysrhythmias from electrolyte issues, lead to cerebral vasodilation, somnolence and even coma
• Alveolar hypoventilation with more alveolar carbon dioxide limits oxygen available, causing secondary hypoxemia

Hypoxemia

• Hypoxemia is reduced arterial blood oxygenation (reduced PaO2) while hypoxia (ischemia) lowered tissue oxygenation from reduced cells in tissues
• Hypoxemia can lead to hypoxia, tissue hypoxia can exist from causes unrelated to lung function
• Hypoxemia results from:
  • Oxygen delivery: Minute breathing (secondary hypoxemia), inspired oxygen
  • Oxygen diffusion: Balance between ventilation and perfusion, diffusion across alveolar capillary barrier
  • Pulmonary system perfusion
• The amount of oxygen in the alveoli (PAO2) depends on alveolar ventilation, which is connected to Hypoventilation sections
• Decreased oxygen leads to secondary hypoxemia with hypercapnia/acidosis (reduced rate/depth breathing)
• Diffusion depends on balanced air/alveoli (V.)/ blood in capillaries (Q), mismatch causes hypoxemia
• Normal V· /Q· is 0.8 (respiratory quotient), mismatch refers to abnormal distribution
• Hypoxemia caused from inadequate alveolar ventilation resulting in wasted perfusion
  • Called shunting, the alveolar ventilation is filled with fluid such as atelectasis, asthma and pneumonia
• Hypoxic vasoconstriction causes localized shunting areas to minimizes blood flow to the areas
• Results in prevents loss of oxygen and improving overall matching and raising the oxygen levels
• Can contribute to elevated pulmonary artery pressures (PH) and right heart failure/cor pulmonale
• Poor perfusion of well-ventilated portions of the lung causes hypoxemia and wasted ventilation
• Pulmonary embolus is the most common cause that impairs blood flow to a segment of the lung
• If alveoli is ventilated but unperfused, it is termed alveolar dead space
• Diseases such as emphysema increase alveolar dead space by destroying tissue
• Impaired oxygen diffusion of the alveolocapillary membrane as affect the diffusion, reduced tissue and thickened membranes
• Hypercapnia is seldom produced by impaired diffusion because CO2 diffuses so easily

Acute Respiratory Failure

• Altered reduction of arterial blood oxygenation(Pa02) less than 60 mm Hg and an increase of arterial carbon dioxide tension(PaC02) greater than 50mm Hg
• Can result from direct injury to the lungs, airways, or chest wall or indirectly because by disease or injury involving another body system
• Ventilatory support is needed for hypercapnic failure
• People may need both ventilation and oxygen support
• Can result as a complication of major surgical procedure
• The most common postoperative pulmonary problems are atelectasis, pneumonia, pulmonary edema, and pulmonary emboli
• People who smoke/are obese,limited cardiac reserve, have neurologic disease, have chronic renal failure or infection are at high risk

Disorders of Chest Wall and Pleura

• The chest wall, pleura can affect the function of the respiratory system
• Reduce tidal volume resulting in poor ventilation and hypercapnia and impacts both ventilation and oxygenation

Chest Wall Restriction

• Chest wall defects, trauma, immobilization, or excessive fat increases the work of breathing and compromised tidal volume
• Severely restrictive chest walls exhibit dyspnea and can lead to respiratory failure
• Kyphoscoliosis/musculoskeletal impair ventilation
• Poliomyelitis, muscular dystrophy, myasthenia gravis, and Guillain-Barré syndrome restrict pulmonary function, and cause hypoventilation
• Chest wall injury/surgery and paradoxical movement of the chest with breathing can cause restriction which increases respiratory rate, and then respiratory failure
• Diagnosed by: lung function,blood gas, and is treated supportively and aimed at the underlying cause