Exam 20 - Introduction to the Resp. System

Introduction to the Respiratory System

• External respiration exchanges oxygen and carbon dioxide between the lungs and environment.
• External respiration involves inhaling air that is warmed, moistened, and filtered.
• The cardiovascular system works with the respiratory system to deliver oxygen for metabolism.
• Failure of either the respiratory or cardiovascular system leads to rapid cell death from oxygen deprivation.
• Internal respiration exchanges oxygen and carbon dioxide at the cellular level.
• Oxygen enters cells, and carbon dioxide leaves them, following a concentration gradient via diffusion.
• The bloodstream transports these gases.

Upper Respiratory Tract

• Air enters through the nares (nasal openings), where it is filtered, moistened, and warmed.
• The nasal septum divides the nares.
• A vascular mucous membrane lining provides warmth and moisture, secreting 1 liter of moisture daily.
• Tiny hairs trap foreign particles, preventing them from entering the lower respiratory tract.
• Turbinates (conchae) are the three scroll-like bones that increase surface area for air warming and moisturizing.
• Paranasal sinuses are hollow cavities (frontal, maxillary, sphenoid, and ethmoid) that lighten the skull, give resonance to the voice, and are lined with mucous membranes.
• Smell receptors are located in the nasal cavity mucosa; they are nerve endings of the olfactory nerve (CN I).
• Nasolacrimal ducts (tear ducts) communicate with the upper nasal chamber, causing nasal secretions during crying.
• The pharynx (throat) is a passageway for both air and food, extending about 5 inches (13 cm) from the base of the skull to the esophagus.
• The nasopharynx is the most superior portion, containing the adenoids (pharyngeal tonsils).
• The oropharynx is posterior to the mouth, containing the palatine tonsils.
• The laryngopharynx is directly superior to the larynx.
• Eustachian tubes connect the nasopharynx to the middle ear, which can lead to ear infections from pharyngeal infections, especially in children.
• The larynx (voice box) connects the pharynx to the trachea and contain vocal cords; the opening between the vocal cords is the glottis.
• The larynx is supported by nine areas of cartilage.
• The thyroid cartilage (Adam's apple) is the largest cartilage area, which enlarges during puberty in males.
• The epiglottis is a leaf-shaped cartilage that protects the larynx during swallowing, preventing food from entering the trachea.
• The trachea is a tube-like structure with C-shaped cartilaginous rings, extending about 4 1/3 inches (11 cm) to the mid-chest, where it divides into the right and left bronchi.
• The trachea is located anterior to the esophagus and connects the larynx with the bronchi.
• The isthmus of the thyroid gland covers the trachea in the neck.
• The open part of the C-shaped cartilage allows esophageal expansion during swallowing, while the trachea remains open for breathing.
• The trachea is lined with mucous membranes and cilia, which move debris upward toward the nasal cavity.
• The cough reflex is triggered by large particles, helping to expel foreign material.

Lower Respiratory Tract

• The left bronchus enters the left lung.
• The right bronchus is larger in diameter and more vertical than the left, making it a common site for aspirated foreign objects.
• The left bronchus is smaller in diameter and more horizontal compared to the right.
• Bronchioles are smaller structures of the bronchi.
• Terminal bronchioles (alveolar ducts) are lined with ciliated mucous membrane.
• Alveoli are terminal structures of the bronchial tree where gas exchange occurs.
• Alveoli have thin walls to facilitate gas exchange.
• Alveoli lie in contact with blood capillaries for diffusion of gases.
• Alveoli are coated with surfactant to reduce surface tension and prevent collapse.

Mechanics of Breathing

• The thoracic cavity is primarily occupied by the lungs.
• The mediastinum (interpleural space) contains the heart and great vessels.
• The intrapleural space is enclosed by the sternum, ribs, and thoracic vertebrae.
• Lungs are paired, spongy, cone-shaped organs.
• The right lung has 3 lobes, and the left lung has 2 lobes.
• Pulmonary arteries carry blood from the heart.
• Gas exchange occurs via diffusion.
• Oxygenated blood returns to the left atrium via pulmonary veins.
• The visceral pleura covers the surface of each lung.
• The parietal pleura covers the walls of the thoracic cavity.
• The pleural cavity is an airtight vacuum with negative pressure that helps keep the lungs inflated.
• Air in the lungs is at atmospheric pressure, which is higher than in the pleural cavity.
• The pleura produces serous fluid to allow the lungs to slide over the thorax during breathing.
• Excess serous secretion leads to pleural effusion, which might require thoracentesis.

Regulation of Respiration

• The medulla oblongata and pons control the basic rhythm and depth of respiration.
• Chemoreceptors are located in the carotid and aortic bodies.
• Chemoreceptors are sensitive to blood carbon dioxide, oxygen, and pH levels.
• Normal arterial blood pH range is 7.35-7.45; normal venous range is 7.31-7.41.
• Respirations are stimulated or suppressed to normalize blood values.
• Increased carbon dioxide, decreased oxygen, or increased acidity trigger nerve impulses to modify respiratory rates.
• Carbon dioxide is the primary chemical stimulant for respiration.

Respiratory Assessment

• The respiratory system is always assessed as part of a patient's general health.
• Patients needing extensive respiratory assessment include those with acute/chronic respiratory/cardiac conditions, history of respiratory impairment, or recent surgery.
• Physical and emotional responses are related; thus, stress and anxiety should be assessed.
• Shortness of Breath (SOB)and Dyspnea on Exertion (DOE) are subjective experiences that only the patient can accurately describe.
  • Assess onset, duration, precipitating factors, and relief measures for SOB and DOE.
• Cough can be productive or non-productive, harsh/dry/hacking, and the color and the amount of expectorated mucous.
• Objective data begins with observation of patient's expression, chest movement, and respiratory expansion.
  • Assess respiratory rate and oxygen saturation.
  • Distress indicators are a wide-eyed, anxious look, flared nostrils, and chest retractions.
  • Orthopnea means the patient must sit or stand to breathe comfortably.
• Auscultation assesses all lung fields for adventitious breath sounds.
  • Sibilant wheeze (wheeze) are high-pitched, squeaking, or whistling sounds due to narrowed bronchioles.
  • Sonorous wheeze (rhonchi) are low-pitched, coarse, snoring sounds, often on expiration.
  • Crackles are short, interrupted crackling or bubbling sounds, usually during inspiration.
  • Pleural friction rubs are low-pitched, grating or creaking sounds when inflamed pleural surfaces rub together.
• Signs/Symptoms of Hypoxia: oxygen deficiency in cellular tissues, apprehension, anxiety, restlessness, decreased concentration, disorientation, decreased consciousness, fatigue, vertigo, behavioral changes, increased pulse (or bradycardia), increased respiratory rate (or shallow/slow respirations), elevated/decreased blood pressure, cardiac dysrhythmias, pallor, cyanosis, clubbing, dyspnea.

Oxygen Therapy

• Various devices are used for oxygen therapy based on patient needs.
• The nurse's skill with these therapies directly affects the patient's outcome.
• Oxygen flow rate is ordered in liters per minute.
• Fraction of inspired oxygen (FiO2) is the percentage or concentration of oxygen delivered.
• Safety precautions are put in place when using oxygen:
  • Because oxygen supports combustion, avoid electric sparks, fire, smoking, open flames, lighters, and candles.
  • No wool blankets, non-fire-resistant clothing, or friction toys should ne used.
  • Electrical equipment must be in good working order with 3-pronged plugs.
  • Avoid petroleum jelly due to combustibility.
  • Oxygen cylinders should not be stored near heat sources.
• Humidification is necessary to prevent drying of the mucous membranes.
• Arterial oxygen levels decrease with age (PaO2 can be 80-85 mmHg).
• The respiratory drive is initiated by rising carbon dioxide levels, but can shift to hypoxia in chronic conditions.
  • In some patients with chronic pulmonary disease, high oxygen can reduce their respiratory drive and cause respiratory difficulty or even stop their breathing.
  • Flow rates > 2 L/min can eliminate respiratory drive in some patients.
• Older adults are prone to skin impairment from nasal cannulas.
• Administration of oxygen requires critical thinking and evaluation of patient's response.
• Oxygen is treated like a drug and must be ordered by a healthcare provider.
• The nurse is responsible for administration of oxygen in the correct manner, adjusting flow rate and evaluating the patient's response; proper device placement may be delegated to UAP, but not flow rate adjustment.
• Oxygen toxicity: High levels of oxygen can cause scarring in the pulmonary tissues and blindness; it is related to the duration of exposure and FiO2, not PaO2.

Oxygen Equipment

• A nasal cannula is a tube inserted into the nasal cavity.
  • Delivers up to 6 liters per minute, providing 24-44% FiO2.
  • Humidify oxygen if flow is greater than 4 L/min.
  • Patients with obstructive pulmonary disease should be given 2-3 liters/minute.
  • Easy to dislodge and has a risk of necrosis.
• A simple face mask has a liter flow of 5-8 L/min, and FiO2 of 35-55%.
• Face masks with reservoirs consist of:
  • Partial rebreather: 6-12 L/min, FiO2 of 60-90%.
  • Non-rebreather: 6-15 L/min, FiO2 of 70-100%; valves prevent the bag from deflating.
  • The reservoir bag must be completely full before being placed on the patient.
• A Venturi (air-entrainment mask) delivers consistent and accurate FiO2 (24-55%), regardless of breathing pattern.

Patient Teaching

• Proper application of oxygen equipment.
• Review safety precautions.
• Stress the dangers of adjusting oxygen flow rate without discussing it with the provider.
• Ambulate or change position frequently to mobilize secretions.
• Teach cough and deep breathing exercises.
• Maintain adequate fluid intake; avoid caffeine and dairy products.
• Teach rationale for prescribed medications and their side effects.
• Perform oral hygiene regularly.

Diagnostic Procedures

• Chest X-Ray: Visualizes the thoracic cavity, lungs, heart, and vessels; identifies lesions, infiltrates, foreign bodies, or fluid, can confirm pneumothorax, pneumonia, pleural effusion, and pulmonary edema.
• Computed Tomography (CT) Scans:Takes detailed pictures of lung tissue; painless, non-invasive, and can be diaganol or cross-sectional.
• Pulmonary Angiography: Uses contrast material to visualize pulmonary vasculature, detecting pulmonary embolism and congenital lesions.
• Ventilation-Perfusion Scan (V/Q Scan): Assesses airflow to alveoli (ventilation) and blood flow to alveoli (perfusion); abnormal scans suggest impaired circulation to the alveoli.
• Pulmonary Function Test (PFT):Assesses the severity of disease in airways; includes lung volume, ventilation, spirometry, and gas exchange tests; measures lung volume, inspiratory capacity, and total lung capacity.
• Mediastinoscopy: Surgical procedure to obtain lymph node samples for biopsy in the upper mediastinum, done under general anesthesia.
• Laryngoscopy: Allows direct or indirect visualization of the larynx, done with local or general anesthesia.
• Bronchoscopy: A bronchoscope is passed into the trachea and bronchi to visualize and examine the tracheobronchial tree, obtain biopsies, or collect secretions.
  • Patient treated as a surgical patient; informed consent is needed; patient is NPO until gag reflex returns.
  • Monitor for laryngeal edema/spasms; blood-streaked sputum is normal after biopsy.
• Sputum Specimen: Obtained for microscopic evaluation; gram stain, and culture and sensitivity.
  • Must be brought up from the lungs; collect before antibiotics and meals.
  • Instruct the patient to inhale deeply, cough forcefully, and expectorate into a sterile container; hypertonic saline aerosol may help.
• Cytology Studies: Performed on bodily secretions to detect abnormal or malignant cells.
• Lung Biopsy: Obtains tissue for evaluation, can be done transbronchially or as an open-lung biopsy.
  • Open-lung biopsy is used when other procedures do not provide diagnosis; chest is opened with thoracotomy incision.
• Thoracentesis: Surgical puncture to aspirate fluid from the pleural space for diagnostic or therapeutic purposes.
  • Fluid is examined for specific gravity, WBCs, RBCs, protein, glucose, pathogens, and abnormal cells.
  • Removal of fluid is limited to 1300 mL to avoid fluid shift and pulmonary edema.
• Arterial Blood Gas (ABG): Essential or diagnosing and monitoring respiratory disorders; measures lungs' ability to exchange oxygen and carbon dioxide and acid-base balance.
  • PaO2: Amount of oxygen dissolved in plasma (mmHg).
  • SaO2: Amount of oxygen bound to hemoglobin (%).
  • Normal values: pH: 7.35-7.45., PaCO2: 35-45 mmHg, PaO2: 80-100 mmHg, HCO3: 21-28 mEq/L, SaO2: 95%.
  • Relationship between pH and PaCO2: As CO2 rises, pH decreases and as CO2 drops, pH rises.
  • Lungs attempt to compensate for metabolic imbalances by adjusting carbon dioxide levels.
  • The kidneys compensate for respiratory imbalances by adjusting HCO3- levels.
  • Performed at the bedside using heparinized syringe and needle to draw blood from the radial artery after the Allen test is performed.
  • Pressure is applied to the puncture site after the blood sample is drawn; the sample is put on ice and sent for analysis.