Gas Exchange Lecture NURN 155 Exam 2

What is gas exchange?

The process of supplying oxygen (O₂) to cells and removing carbon dioxide (CO₂). In the alveoli, O₂ enters the blood and CO₂ moves into the alveoli.

What is the difference between ventilation and gas exchange?

Ventilation: Movement of air into and out of the lungs. Gas exchange: O₂ and CO₂ move between the alveoli and blood through diffusion.

What is the main function of the respiratory system?

To provide oxygen to the body's cells and eliminate carbon dioxide through breathing and gas exchange.

What structures make up the upper and lower airways?

Upper: Nose, pharynx, larynx, and epiglottis. Lower: Trachea, bronchi, bronchioles, and alveoli.

What are the main organs and structures involved in respiration?

Lungs: Main respiratory organs. Alveoli: Site of gas exchange. Diaphragm and external intercostals: Primary muscles of inspiration.

What should the nurse assess in a respiratory health history?

Current symptoms, past respiratory illnesses, medications, allergies, smoking/vaping, environmental and occupational exposures, family history, and home oxygen or respiratory equipment.

What symptoms should the nurse ask about during a respiratory interview?

Shortness of breath, cough, sputum, wheezing, chest pain, fever, chills, and changes in activity tolerance.

What factors increase a patient's risk for respiratory problems?

Smoking/vaping, secondhand smoke, pollution, occupational dust, allergens, family history, obesity, chronic illness, inactivity, and age-related changes.

How does the nurse assess a patient's smoking history?

Ask about tobacco use, packs per day, years smoked, and secondhand smoke exposure. Pack-years = packs per day × years smoked.

What home respiratory treatments should the nurse ask about?

Prescribed oxygen, inhalers, nebulizers, CPAP, BiPAP, and other respiratory medications or devices.

What are normal adult respiratory rate and oxygen saturation values?

Respiratory rate: 12–20 breaths/min at rest. SpO₂: Usually 95–100% in a healthy adult at sea level.

What is eupnea?

Normal, regular, effortless breathing at approximately 12–20 breaths/min in adults.

What is tachypnea?

Abnormally rapid breathing, greater than 20 breaths/min in adults.

What is bradypnea?

Abnormally slow breathing, fewer than 12 breaths/min in adults.

What is apnea?

Temporary absence or cessation of breathing.

What is hyperventilation?

Breathing faster or deeper than needed, causing excessive CO₂ loss and potentially respiratory alkalosis (increased blood pH).

What is hypoventilation?

Inadequate ventilation from slow or shallow breathing, causing CO₂ retention and potentially respiratory acidosis (decreased blood pH).

What is apneustic breathing?

Prolonged inspiration with a pause followed by inadequate exhalation; associated with brainstem dysfunction.

What is Cheyne-Stokes breathing?

Breathing that gradually increases and decreases in depth, followed by periods of apnea.

What is Kussmaul breathing?

Deep, rapid, labored breathing associated with metabolic acidosis, especially diabetic ketoacidosis (DKA).

What is air trapping?

Incomplete exhalation causes air to remain in the lungs, commonly associated with emphysema and other obstructive respiratory conditions.

What is dyspnea, and what is orthopnea?

Dyspnea: Difficult or uncomfortable breathing. Orthopnea: Difficulty breathing when lying flat, relieved by sitting upright.

What is the tripod position?

Leaning forward with hands supported on the knees or another surface to assist breathing during respiratory distress.

Where does the respiratory assessment fit into a head-to-toe assessment?

After the general survey and vital signs, assess the chest and respiratory system systematically using inspection, palpation, percussion, and auscultation as appropriate.

What should the nurse assess during respiratory inspection?

Level of consciousness, respiratory rate, rhythm, depth, effort, skin color, chest shape, symmetry, movement, and positioning.

What are normal findings during respiratory inspection?

Quiet, effortless breathing; symmetrical chest expansion; relaxed posture; and normal skin color without accessory muscle use.

What abnormal findings indicate increased work of breathing?

Accessory muscle use, nasal flaring, retractions, pursed-lip breathing, tripod positioning, or difficulty speaking in full sentences.

What is the normal chest shape, and what does barrel chest indicate?

Normal adult AP-to-lateral chest ratio: Approximately 1:2. Barrel chest: Increased AP diameter, commonly associated with chronic hyperinflation such as emphysema.

What skin and nail abnormalities should the nurse assess?

Cyanosis: Bluish discoloration associated with low oxygen. Pallor: Unusual paleness, possibly from anemia or poor perfusion. Clubbing: Rounded, enlarged fingertips associated with some chronic respiratory diseases.

What should the nurse assess when evaluating a cough and sputum?

Cough: Dry or productive, frequency, duration, and severity. Sputum: Amount, color, consistency, odor, and presence of blood.

What should the nurse assess when palpating the chest?

Tenderness, masses, crepitus, tracheal position, and symmetrical chest expansion.

What is crepitus during chest palpation?

A crackling sensation beneath the skin that can indicate air trapped in subcutaneous tissue.

What is the purpose of chest percussion?

To assess underlying lung density by tapping the chest wall and listening to the resulting sounds.

What are normal and abnormal lung percussion sounds?

Normal: Resonance, a low-pitched hollow sound. Dullness: Suggests denser tissue or fluid. Hyperresonance: Suggests excess air, as in emphysema or pneumothorax.

How should the nurse perform lung auscultation?

Place the diaphragm on bare skin, ask the patient to breathe deeply through the mouth, listen through complete breaths, and compare matching locations side-to-side from top to bottom. Follow the course's systematic pattern of at least 8 anterior and 12 posterior sites.

What are the three main normal lung sounds?

Bronchial: Loud, high-pitched; heard over the large central airways. Bronchovesicular: Medium-pitched; heard near the main bronchi. Vesicular: Soft, low-pitched; heard over most peripheral lung fields.

What are crackles, and what causes them?

Discontinuous popping or crackling sounds caused by reopening small airways or air movement through fluid or secretions.

What is the difference between fine and coarse crackles?

Fine: Soft, brief, high-pitched popping, usually during inspiration. Coarse: Louder, lower-pitched, wet bubbling sounds, heard during inspiration and sometimes expiration.

What are rhonchi, and what do they indicate?

Continuous, low-pitched snoring or rattling sounds associated with secretions in larger airways. They may improve after coughing.

What are wheezes, and what causes them?

Continuous, musical, high-pitched sounds caused by narrowed airways. Usually heard during expiration but may also occur during inspiration.

What is stridor, and why is it an emergency finding?

A harsh, high-pitched sound, usually during inspiration, caused by upper airway narrowing or obstruction. Sudden stridor requires immediate airway assessment and emergency assistance.

What is a pleural friction rub?

A grating, leather-rubbing sound caused by inflamed pleural surfaces rubbing together. Often accompanied by sharp pain when breathing.

Which abnormal breath sounds may occur with pneumonia?

Crackles and sometimes rhonchi or diminished breath sounds. Findings vary and do not diagnose pneumonia alone.

What does a sudden decrease or absence of breath sounds indicate?

Possible serious airflow or lung problems, such as airway obstruction, pneumothorax, atelectasis, or pleural effusion. Assess promptly and report concerning changes.

What equipment is commonly used in respiratory care?

Pulse oximeter, oxygen flowmeter, nasal cannula, oxygen masks, CPAP/BiPAP, suction equipment, and incentive spirometer.

What is a nasal cannula, and what oxygen levels does it provide?

Two prongs placed in the nares for low-flow oxygen delivery. Flow: 1–6 L/min. Approximate FiO₂: 24–44%.

What is a simple face mask, and what oxygen levels does it provide?

A mask covering the nose and mouth with exhalation ports. Flow: 6–10 L/min. Approximate FiO₂: 35–50%. Maintain sufficient flow to prevent CO₂ rebreathing.

What is a Venturi mask, and what makes it different from other oxygen devices?

A mask with color-coded adapters that delivers a precise, controlled oxygen concentration. FiO₂: Approximately 24–60%, depending on the device. Set the flow according to the adapter's instructions.

What is a non-rebreather mask, and what oxygen levels does it provide?

A face mask connected to a reservoir bag with one-way valves that limit rebreathing. Flow: 10–15 L/min. Approximate FiO₂: 60–80% (varies by fit and device). Keep the reservoir bag partially inflated during inspiration.

What is a partial rebreather mask, and how does it differ from a non-rebreather?

A mask with a reservoir bag but no one-way valve between the mask and bag, allowing some exhaled air to be rebreathed. Flow: Commonly 10–15 L/min. FiO₂: 35–50% as listed in the course material. Keep the reservoir partially inflated.

What is the difference between oxygen flow rate and FiO₂?

Flow rate (L/min): Amount of oxygen delivered each minute. FiO₂ (%): Percentage of oxygen in the gas the patient inhales.

What is the difference between CPAP and BiPAP?

CPAP: One continuous positive airway pressure during inhalation and exhalation. BiPAP: Two pressure levels—higher during inhalation and lower during exhalation.

What is the purpose of suctioning equipment, and what components does it contain?

Removes mucus, fluid, or secretions from the airway using negative pressure. Components: Suction source, tubing, collection canister, and suction catheter/device.

What is the purpose of incentive spirometry?

Encourages slow, deep inhalation to expand the lungs and help prevent atelectasis. Teach the patient to inhale slowly through the mouthpiece, hold briefly, and exhale normally.

What safety precautions must the nurse follow when administering oxygen?

Treat oxygen as a medication; verify the order and settings, prohibit smoking, avoid flames and heat sources, secure cylinders, check equipment, and use oxygen-safe products.

What should the nurse assess before starting supplemental oxygen?

Respiratory rate, rhythm, depth, effort, SpO₂, lung sounds, mental status, skin color, and prescribed oxygen device and flow rate.

What should the nurse monitor while a patient receives supplemental oxygen?

SpO₂, breathing effort, respiratory rate, lung sounds, mental status, comfort, device position, tubing connections, prescribed settings, and response to therapy.

What complications should the nurse monitor for with oxygen devices?

Dry or irritated mucous membranes, skin breakdown behind the ears or around the nose, poor mask fit, equipment malfunction, and inadequate oxygen delivery.

What is pulse oximetry, and what does it measure?

A noninvasive method using a sensor to estimate the percentage of hemoglobin saturated with oxygen (SpO₂). It does not directly measure ventilation or CO₂ levels.

What are normal SpO₂ findings based on age?

Healthy children and adults: Generally 95–100% at sea level. Healthy newborns: SpO₂ is initially lower immediately after birth and rises during normal transition. Older adults: Usually the same general range, but assess individual baseline and prescribed targets.

What factors can interfere with accurate pulse oximetry?

Movement, cold extremities, poor circulation, nail polish/artificial nails, improper probe placement, and bright external light. Carbon monoxide can cause falsely reassuring readings.

What should the nurse do if a patient has an unexpectedly low SpO₂?

Immediately assess breathing, airway, effort, mental status, and oxygen delivery. Verify probe accuracy without delaying care. Position the patient, intervene per protocol, and promptly escalate persistent hypoxemia or respiratory distress.

What are arterial blood gases (ABGs), and what are normal adult values?

ABGs evaluate oxygenation, ventilation, and acid-base balance. pH: 7.35–7.45 PaCO₂: 35–45 mmHg PaO₂: 80–100 mmHg HCO₃⁻: 22–26 mEq/L

Why is a complete blood count (CBC) used in respiratory assessment, and what findings are normal?

WBC: Evaluates infection; approximately 4,500–11,000/µL. Hemoglobin: Carries oxygen; commonly about 12–17.5 g/dL in adults, varying by sex and laboratory. Hematocrit and RBC count: Evaluate red blood cell status; compare with laboratory reference ranges.

What is the purpose of sputum analysis, and what is a normal finding?

Examines respiratory secretions for infectious organisms or abnormal cells. Normal: No significant pathogens identified; sample findings depend on the ordered test.

What are chest X-rays and CT scans used for, and what are normal findings?

Chest X-ray: Evaluates lung fields and chest structures; normally clear lungs without acute infiltrates, effusions, or pneumothorax. CT: Provides detailed images; normally no acute abnormality of the evaluated structures.

What pediatric and older-adult factors affect respiratory function?

Infants/children: Narrower airways, fewer alveoli early in life, higher metabolic demand, and faster respiratory rates; premature newborns may lack sufficient surfactant. Older adults: Reduced chest elasticity, weaker respiratory muscles, decreased cough effectiveness, and increased infection risk.

What health promotion teaching helps maintain respiratory wellness?

Avoid smoking/vaping and secondhand smoke, reduce exposure to pollutants, stay physically active, practice hand hygiene, receive recommended vaccinations, and use prescribed respiratory treatments correctly.

How should the nurse document a respiratory assessment?

Document respiratory rate, rhythm, depth, effort, SpO₂, oxygen device and flow, lung sounds and locations, chest symmetry, cough/sputum, abnormal findings, interventions, and patient response using objective terminology.

When and to whom should the nurse communicate abnormal respiratory findings?

Immediately escalate severe dyspnea, stridor, cyanosis, sudden confusion, markedly increased work of breathing, or acute deterioration to the rapid response/emergency team per protocol. Promptly notify the responsible RN/provider of new abnormal findings, falling SpO₂, or changes from baseline.