Respiratory System: External and Internal Respiration

• Cells need continuous oxygen for specialized functions.
• External respiration (breathing) involves the exchange of oxygen and carbon dioxide between lungs and environment.
• The respiratory system delivers oxygen to cells for metabolism, working with the cardiovascular system.
• Internal respiration involves oxygen and carbon dioxide exchange at the cellular level.
• The bloodstream transports gases, with oxygen entering cells and carbon dioxide leaving.
• Respiratory or cardiovascular system failure leads to rapid cell death from oxygen deprivation.

Upper Respiratory Tract: Nose

• Air enters through the nose, getting filtered, moistened, and warmed.
• Air enters through the nares (nasal openings) and proceeds to the nasal cavity.
• The nasal septum separates the nares.
• Mucous membrane lines this area, providing warmth and moisture, secreting 1 L of moisture daily.
• Turbinates/conchae (scroll-like bones) increase surface area for warming and moisturizing air.
• Tiny hairs in the nasal cavities trap dust and foreign particles.
• Paranasal sinuses (frontal, maxillary, sphenoid, ethmoid) communicate with nasal structures.
• Sinuses lighten the skull and may give resonance to the voice
• They are lined with mucous membranes continuous with the nasal cavity, which can lead to sinusitis.
• Olfactory nerve endings (first cranial nerve) are receptors for smell in the nasal mucosa.
• Nasolacrimal ducts (tear ducts) connect to the upper nasal chamber.

Pharynx

• The pharynx (throat) is a 5-inch (13 cm) tube from the skull base to the esophagus, in front of the vertebrae.
• The pharynx is a passageway for air and food.
• The pharynx has the subdivisions: nasopharynx, oropharynx, and laryngopharynx.
• Eustachian tubes connect the nasopharynx to the middle ear.
• Infections can spread from the pharynx to the ear due to continuous linings of the pharynx and Eustachian tube
• Adenoids (pharyngeal tonsils) are in the nasopharynx, and palatine tonsils are in the oropharynx.

Larynx

• The larynx (voice box) connects the pharynx to the trachea and is supported by nine cartilages.
• The thyroid cartilage ("Adam’s apple") is the largest cartilage, enlarging in boys during puberty.
• The epiglottis (leaf-shaped cartilage) protects the larynx during swallowing.
• The epiglottis covers the larynx to prevent food from entering the trachea, instead directing food to the esophagus
• The larynx contains vocal cords which vibrate to enable speech during expiration
• The glottis is the opening between the vocal cords.

Trachea

• The trachea (windpipe) extends about 4 1/3 inches (11 cm) to mid-chest; it divides into bronchi.
• It is anterior to the esophagus, connecting the larynx to the bronchi.
• The isthmus of the thyroid gland covers it in the neck.
• C-shaped cartilaginous rings keep the trachea from collapsing.
• The open part of the C-rings faces posteriorly to allow esophageal expansion during swallowing.
• Mucous membranes and cilia line the trachea, sweeping debris towards the nasal cavity.
• Large particles trigger the cough reflex.

Bronchial Tree

• The trachea divides into the right and left main bronchi.
• Each bronchus enters a lung and branches into secondary bronchi, then smaller bronchioles.
• Terminal bronchioles (alveolar ducts) are the smaller tubelike divisions.
• The trachea and all structures are lined with ciliated mucous membrane.
• Alveoli are the end structures of the bronchial tree; sac-like structures resembling grapes.
• Gas exchange occurs in the alveoli, which are surrounded by blood capillaries.
• Diffusion of carbon dioxide and oxygen happens in the alveoli.
• Alveoli have thin walls and are in contact with blood capillaries for gas exchange,.
• Surfactant coats each alveolus, reducing surface tension to prevent collapse after each breath.
• Lungs contain millions of alveoli.
• Alveoli are the most important part of the respiratory system where oxygen diffuses into the cardiovascular system.

Mechanics of Breathing: Thoracic Cavity

• The thoracic cavity is enclosed by the sternum, ribs, and thoracic vertebrae.
• The lungs occupy most of the space within the cavity.
• The mediastinum (interpleural space) is the centermost area, containing the heart and great vessels.

Lungs

• The lungs are paired, spongy, cone-shaped organs.
• The right lung weighs about 625 g and has three lobes; the left lung weighs about 570 g and has two lobes.
• The apex (narrow part) of each lung is about 1 inch (2.5 cm) above the first rib.
• The base (broad, inferior part) lies on the diaphragm.
• Lungs receive blood from the heart through the pulmonary arteries.
• Lung capillaries contain blood low in oxygen.
• Alveoli air is rich in oxygen; oxygen diffuses from alveolar air to lung capillaries.
• Lung capillaries are high in carbon dioxide, which diffuses into the alveoli.
• Carbon dioxide leaves the body through expiration.
• Blood, now rich in oxygen and cleansed of carbon dioxide, returns to the heart via pulmonary veins.
• Visceral pleura (serous membrane) covers each lung.
• Parietal pleura covers the walls of the thoracic cavity.
• Pleural cavity is an airtight vacuum around the lungs with negative pressure, keeping the lungs inflated.
• Both visceral and parietal pleura produce a serous secretion, allowing lungs to slide during breathing.
• Pleural effusion is the accumulation of excess serous secretion in the pleural space.
• Pleural effusion can cause pressure on the lungs, leading to breathing difficulties, which may be treated with thoracentesis

Respiratory Movements and Ranges

• Respiratory movements comprise rhythmic movements of chest walls, ribs, and associated muscles during breathing.
• One inspiration and one expiration make up one respiration.
• At rest, normal inspiration lasts about 2 seconds, and expiration lasts about 3 seconds.
• Inhaled room air contains about 21% oxygen; exhaled air contains 16% oxygen and 3.5% carbon dioxide.
• The normal adult respiratory rate is 14 to 20 breaths per minute, depending on age, sex, activity, disease, and body temperature.
• Newborns breathe 40 to 60 breaths/min, early school-age children breathe 22 to 24 breaths/min, and teenagers breathe 20 to 22 breaths/min.
• The health care team needs to assess respiration factors and count respirations without patient awareness.

Regulation of Respiration: Nervous Control

• The medulla oblongata and pons control the basic rhythm and depth of respiration.
• Body demands can modify the respiratory rhythm.
• Chemoreceptors in the carotid artery and aorta (carotid and aortic bodies) are specialized receptors.
• These receptors are stimulated by increased blood carbon dioxide, decreased oxygen, or increased acidity.
• The receptors send nerve impulses to respiratory centers, which modify respiratory rates.
• Carbon dioxide is the chemical stimulant because it is present in the blood as carbonic acid.
• Normal blood pH is 7.35 to 7.45.
• Acidosis means too much acid (e.g., carbon dioxide) in the blood.
• Alkalosis means not enough carbon dioxide (too much base) in the blood.
• The blood becomes more alkaline after exhalation.

Assessment of the Respiratory System

• Respiratory system function is gas exchange at the alveolus-capillary level.
• This function depends on the lungs' ability to expand, influenced by musculoskeletal and neurologic functions.
• Physical assessment always includes the respiratory system.
• Acute/chronic respiratory or cardiac conditions require extensive assessments.
• Look for respiratory impairment related to trauma, allergies, surgery, or anesthesia.
• Inquire about anxiety or stress in a matter-of-fact way.
• Assessment includes collecting subjective data.
• Encourage patients to describe symptoms (shortness of breath, dyspnea).
• Dyspnea (difficulty breathing) is a subjective experience.
• Record onset, duration, factors, and relief measures of symptoms.
• For a cough, describe if it is productive or nonproductive; harsh, dry, or hacking; and color and amount of mucus expectorated.
• Collect objective data by observation.
• Assess respiratory rate and oxygen saturation.
• Wide-eyed, anxious look may indicate fear of suffocating.
• Flaring nostrils usually indicate difficulty breathing
• Patient may not be able to verbalize distress.
• Assess skin color and turgor.
• Note respiratory distress, wheezes, or orthopnea (difficulty breathing while lying down).
• Auscultate all lung fields, comparing bilaterally.
• Note adventitious sounds (abnormal sounds superimposed on breath sounds).
• Sibilant wheezes are squeaking or whistling sounds caused by air moving through narrowed bronchioles.
• Sonorous wheezes are low-pitched, loud, snoring sounds, often on expiration.
• Crackles are interrupted crackling or bubbling sounds, often sound like hairs being rolled between fingers, that are usually heard during inspiration.
• Crackles occur when air is forced through respiratory passages narrowed by fluid, mucus, or pus and are associated with inflammation or infection.
• Pleural friction rubs are low-pitched, grating, or creaking sounds when inflamed pleural surfaces rub together.
• Assess chest movement for equal expansion.
• Unequal chest expansion may mean pulmonary complications, such as lung collapse.
• Retraction of the chest wall may signal late-stage respiratory distress.
• Monitor for signs and symptoms of hypoxia (oxygen deficiency).

Laboratory and Diagnostic Examinations

• Diagnostic imaging, laboratory work, and invasive measures assess the respiratory system.
• Nurses should know these tests to prepare patients.

Chest X-Ray

• Radiographs are essential for evaluating chest disorders.
• Chest x-rays visualize the thoracic cavity, lungs, heart, and major vessels.
• X-rays show changes in size, location, blood flow, lesions, infiltrates, foreign bodies, or fluid.
• They show involvement of lung parenchyma (tissue) or interstitial spaces.
• Chest x-rays confirm pneumothorax, pneumonia, pleural effusion, and pulmonary edema.

Computed Tomography (CT Scan)

• CT scans provide pictures of small layers of pulmonary tissue to identify lesions.
• Views can be diagonal or cross-sectional.
• Preparation is necessary to explain procedure and reduce anxiety, although this test is painless and noninvasive.

Helical/Spiral CT Chest Scan

• Helical CT scanning continuously obtains images faster
• Helical CT can scan the abdomen and chest in under 30 seconds, with one breath-hold.
• The injection or swallowing of contrast dye helps organs or tissues show up clearly.

Pulmonary Angiography

• Pulmonary angiography (arteriography) uses contrast material injected into pulmonary arteries to visualize vessels.
• Angiography detects pulmonary embolism (PE) and congenital/acquired lesions.
• A CT scan is typically performed first when PE is suspected.
• A normal lung scan rules out PE; an uncertain scan questions PE diagnosis.
• A definitive diagnosis for PE needs pulmonary angiography.

Ventilation-Perfusion Scan (V/Q Scan)

• V/Q scanning is used to check primarily for PE.
• Ventilation (V) is the air reaching alveoli; perfusion (Q) is the blood reaching alveoli.
• A radioisotope is given intravenously for the perfusion part, creating an image of vasculature.
• For ventilation, the patient inhales radioactive gas, creating an alveoli outline.
• Normal scans show homogeneous radioactivity.
• High V/Q means impaired blood circulation to alveoli (suggesting PE).

Pulmonary Function Testing (PFTs)

• PFTs assess the presence and severity of disease in large and small airways.
• PFTs include procedures for lung volume, ventilation, spirometry, and gas exchange.
• Lung volume tests measure air exhaled completely after maximum inhalation (vital capacity).
• Inspiratory capacity is the air inhaled in one breath from the resting expiratory level.
• Total lung capacity is the air in the lung volume after a maximal inhalation.
• Ventilation tests evaluate air inhaled/exhaled in each respiratory cycle.
• Pulmonary spirometry tests evaluate air exhaled forcefully after maximum inhalation, using a spirometer.
• A DLCO (diffusing capacity of the lungs for carbon monoxide) test is used when determining gas exchange to determine how well oxygen diffusing from the alveoli is taken up by blood in the pulmonarycapillary bed.
• Instead of oxygen, a small, non-dangerous amount of carbon monoxide is used.
• After the DLCO test the patient's rate of oxygen transfer can be determined accurately.

Mediastinoscopy

• Mediastinoscopy is a surgical endoscopic procedure that involves creating an incision in the suprasternal notch (neck base) to pass an endoscope into the upper mediastinum.
• A biopsy is performed, taking sample lymph nodes.
• The lymph nodes are examined for a tumor, where samples are gathered for analyzation.
• Tumors in the mediastinum (e.g., thymoma or lymphoma) can also be biopsied.
• Lymph nodes receive drainage from the lungs, being valuable in diagnosis for malignant tumours.
• This procedure is performed in the operating room under general anesthesia.

Laryngoscopy

• Laryngoscopy visualizes the larynx, either directly or indirectly.
• An indirect laryngoscopy is the most common procedure for assessing respiratory difficulties.
• A laryngeal mirror is positioned in the mouth for visualization, with the patient awake.
• A direct laryngoscopy uses a laryngoscope for biopsy or polyp excision.
• Direct laryngoscopy involves anesthesia and exposes the vocal cords as the scope is passed over the tongue.

Bronchoscopy

• Bronchoscopy involves passing a bronchoscope into the trachea and bronchi.
• A flexible fiberoptic bronchoscope is the instrument of choice.
• Visualization includes the larynx, trachea, and bronchi.
• Diagnostic bronchoscopy includes observing the tracheobronchial tree for abnormalities
• Diagnostic bronchoscopy includes biopsies, and collecting secretions for examination.
• Local anesthesia or intravenous (IV) general anesthesia is usually given.
• The patient is treated as a surgical patient.
• Post-bronchoscopy nursing involves monitoring the patient as safety is a priority.
• Keeping the patient on NPO (nothing by mouth) status until the gag reflex returns, usually about 2 hours after the procedure;
• Keeping the patient in a semi-Fowler’s position and turning on either side to facilitate removal of secretions (unless the health care provider specifies another position);
• Monitoring the patient for signs of laryngeal edema or laryngospasms, such as stridor or increasing dyspnea;
• Monitoring sputum for hemorrhage if lung tissue biopsy is taken (blood-streaked sputum is expected for a few days after biopsy).

Sputum Specimen

• Frequent Sputum samples are obtained for for microscopic evaluation, such as Gram stain and culture and sensitivity

Cytologic Studies

• Cytologic tests can be performed on any body secretion, such as sputum or pleural fluid, to detect abnormal or malignant cells.

Lung Biopsy

• Lung biopsy can be done transbronchially or as an open-lung biopsy.
• The purpose is to obtain tissue, cells, or secretions for evaluation
• A transbronchial lung biopsy involves passing a forceps or needle through the bronchoscope to obtain a specimen.
• Specimens can be cultured or examined for malignant cells.
• Nursing interventions are the same as for fiberoptic bronchoscopy.
• Open-lung biopsy is used when pulmonary disease cannot be diagnosed by other procedures.
• The patient is anesthetized, a chest thoracotomy incision, and a specimen is obtained.