Respiratory System

RESPIRATORY FUNCTION
The major function of the pulmonary system (lungs and pulmonary circulation) is to deliver oxygen to cells and remove carbon dioxide (CO2) from the cells (gas exchange). The adequacy of oxygenation and ventilation is measured by partial pressure of arterial oxygen (PaO2) and partial pressure of arterial carbon dioxide (Paco2). The pulmonary system also functions as a blood reservoir for the left ventricle when it is needed to boost cardiac output; as a protector for the systemic circulation by filtering debris/particles; as a fluid regulator so water can be kept away from alveoli; and as a provider of metabolic functions such as surfactant production and endocrine functions.

Terminology
  • Alveolus -air sac where gas exchange takes place
  • Apex- top portion of the upper lobes of lungs
  • Base- bottom portion of lower lobes, located just above the diaphragm
  • Bronchoconstriction- constriction of smooth muscle surrounding bronchioles
  • Bronchus- large airways; lung divides into right and left bronchi
  • Carina- location of division of the right and left main stem bronchi
  • Cilia- hairlike projections on the tracheobronchial surface lining, which aid in the movement of secretions and debris
  • Compliance- ability of the lungs to distend (eg, emphysema, lungs very compliant; fibrosis lungs noncompliant or stiff)
  • Dead space- ventilation that does not participate in gas exchange; also known as wasted ventilation when there is adequate ventilation but no perfusion, as in pulmonary embolus or pulmonary vascular bed occlusion. Normal dead space is 150 ml.
  • Diaphragm- dome-shaped muscle; the primary muscle used for respiration (located just below the lung bases)
  • Diffusion (of gas)- movement of gases from a higher to lower concentration
  • Dyspnea- subjective sensation associated with unpleasant, uncomfortable respiratory sensations, often caused by a dissociation between motor command and mechanical response of the respiratory system such as:
    • Respiratory muscle abnormalities (hyperinflation and airflow limitation from chronic obstructive pulmonary disease [COPD]).
    • Abnormal ventilatory impedance (narrowing airways and respiratory impedance from COPD or asthma).
    • Abnormal breathing patterns (severe exercise, pulmonary congestion or edema, recurrent pulmonary emboli).
    • Arterial blood gas (ABG) abnormalities (hypoxemia, hypercarbia).
  • Hemoptysis- bleeding from the lung; main symptom is coughing up blood
  • Hypoxemia- PaO2 less than normal, which may or may not cause symptoms (Normal PaO2 is 80 to 100 mm Hg on room air.)
  • Hypoxia- insufficient oxygenation at the cellular level due to an imbalance in oxygen delivery and oxygen consumption (Usually causes symptoms reflecting decreased oxygen reaching the brain and heart.)
  • Mediastinum- compartment between lungs containing lymph and vascular tissue that separates left from right lung
  • Orthopnea- shortness of breath when in reclining position
  • Paroxysmal nocturnal dyspnea (PND)- shortness of breath with sudden onset; occurs after going to sleep in recumbent position
  • Perfusion- blood flow, carrying oxygen and CO2 that passes by alveoli
  • Pleura- membrane that covers the outside of the lung (visceral pleura) and lines the thorax (parietal pleura) that creates a potential space
  • Pulmonary circulation (bronchial circulation)- circulatory system that supplies oxygenated blood to the respiratory system
  • Respiration- gas exchange from air to blood and blood to body cells
  • Shunt- adequate perfusion without ventilation, with deoxygenated blood conducted into the systemic circulation, as in pulmonary edema, atelectasis, pneumonia, COPD
  • Surfactant- substance released by cells within the lung; maintains surface tension and keeps alveoli open allowing for better gas exchange
  • Ventilation- movement of air (gases) in and out of the lungs
  • Ventilation-perfusion ([V with dot above]/[Q with dot above]) imbalance or mismatch- imbalance of ventilation and perfusion; a cause for hypoxemia. [V with dot above]/[Q with dot above] mismatch can be due to:
    • Blood perfusing an area of the lung where ventilation is reduced or absent.
    • Ventilation of parts of lung that are not perfused.
ASSESSMENT

SUBJECTIVE DATA

Explore the patient's symptoms through characterization and history taking to help anticipate needs and plan care.

Dyspnea
  • Characteristics- Is the dyspnea acute or chronic? Has it come about suddenly or gradually? Is more than one pillow required to sleep? Is the dyspnea progressive, recurrent, or paroxysmal? Walking how far leads to shortness of breath? How does it compare to the patient's baseline level of dyspnea?

    Ask patient to rate dyspnea on a scale of 1 to 10 scale with 1 being no dyspnea and 10 being the worst imaginable. What relieves and what aggravates the dyspnea?
  • Associated factors- Is there a cough associated with the dyspnea and is it productive? What activities precipitate the shortness of breath? Does it seem to be worse when upset? Is it influenced by the time of day, seasons and/or certain environments? Does it occur at rest or with exertion? Any fever, chills, night sweats? Any change in body weight?
  • History- Is there a patient history or family history of chronic lung disease, cardiac or neuromuscular disease? What is the smoking history?
  • Significance- Sudden dyspnea could indicate pulmonary embolus, pneumothorax, myocardial infarction, acute ventricular failure, or acute respiratory failure. In a postsurgical or postpartum patient, dyspnea may indicate pulmonary embolus or edema. Orthopnea can be indicative of heart disease or COPD. If dyspnea is associated with a wheeze, consider asthma, COPD, or heart failure.
Chest Pain
  • Characteristicsรข€”Is the pain sharp, dull, stabbing, or aching? Is it intermittent or persistent? Is the pain localized or does it radiate? If it radiates, where? How intense is the pain? Are there factors that alleviate or aggravate the pain, such as position or activity?
  • Associated factors- What effect do inspiration and expiration have on the pain? What other symptoms accompany the chest pain? Is there diaphoresis, shortness of breath, nausea?
  • History- Is there a smoking history or environmental exposure? Has the pain ever been experienced before? What was the cause? Is there a preexisting pulmonary or cardiac diagnosis?
  • Significance- Chest pain related to pulmonary causes is usually felt on the side where pathology arises, but it can be referred. Dull persistent pain may indicate carcinoma of the lung, whereas sharp stabbing pain usually arises from the pleura.
Cough
  • Characteristics- Is the cough dry, hacking, wheezy, or more like clearing the throat? Is it strong or weak? How frequent is it? Is it worse at night or at any time of day? Is it aggravated by food intake or exertion; is it alleviated by any medication? How long has it been going on?
  • Associated factors- Is the cough productive? If so, what is the consistency, amount, color, and odor of the sputum? How does sputum compare to the patient's baseline? Is it associated with shortness of breath or pain?
  • History- Has there been any environmental or occupational exposure to dust, fumes, or gases that could lead to cough? Is there a smoking history? Is the smoking current or in past? Are there past pulmonary diagnoses, asthma, rhinitis, allergy or exposure to allergens such as pollen, house dust mites, animal dander, mold, cockroach waste, irritants (smoke, odors, perfumes, cleaning products, exhaust, pollution, cold air)? Does the patient have a history of acid reflux or use an angiotensin-converting enzyme (ACE) inhibitor whose major adverse effect is cough?
  • Significance- A dry, irritative cough may indicate viral respiratory tract infection. A cough at night should alert to potential left-sided heart failure, asthma, or just postnasal drip worsening at night. A morning cough with sputum might be bronchitis. A severe or changing cough should be evaluated for bronchogenic carcinoma. Consider bacterial pneumonia if sputum is rusty, and lung tumor if it is pink-tinged. A profuse pink frothy sputum could be indicative of pulmonary edema. A cough associated with food intake could indicate problems with aspiration. A dry cough may be associated with pulmonary fibrosis.
Hemoptysis
  • Characteristics- Is the blood from the lungs? It could be from gastrointestinal system (hematemesis) or upper airway (epistaxis). Is it bright red and frothy? How much? Is onset associated with certain circumstances or activities? Was the onset sudden, and is it intermittent or continuous?
  • Associated factors- Was there an initial sensation of tickling in the throat? Was there a salty taste, burning or bubbling sensation in the chest before bleeding? Has there been shortness of breath, chest pain, difficulty with exertion?
  • History- Was there any recent chest trauma or respiratory treatment (chest percussion)? Does the patient have an upper respiratory infection, sinusitis, or recent epistaxis?
  • Significance- Hemoptysis can be linked to pulmonary infection, lung carcinoma, abnormalities of the heart or blood vessels, pulmonary artery or vein abnormalities, or pulmonary emboli and infarction. Small amounts of blood-tinged sputum may be from the upper respiratory tract, and regurgitation of blood comes from a GI bleed.

PHYSICAL EXAMINATION

Perform a physical examination of the chest using inspection, palpation, percussion, and auscultation to determine respiratory status and differentiate primary lung problems from cardiac problems.

Key Observations
  • What is the respiratory rate, depth, and pattern? Are accessory muscles being used? Is sputum being raised, and what does it look like?
  • Is there an increase in the anterior to posterior chest diameter, suggesting air trapping?
  • Is there clubbing of the fingers, associated with bronchiectasis, lung abscess, empyema, cystic fibrosis, pulmonary neoplasms, and various other disorders?
  • Is there central cyanosis indicating possible hypoxemia or cardiac disease?
  • Are the jugular veins distended? Is there peripheral edema or other signs of cardiac dysfunction?
  • Does palpation of the chest cause pain? Is chest expansion symmetric? Any change in tactile fremitus?
  • Is percussion of lung fields resonant bilaterally? Is diaphragmatic excursion equal bilaterally?
  • Are the lung fields clear or are there rhonchi, wheezing, or crackles? Are breath sounds equal bilaterally?.
Mga etiketa: