real real week 5 [ptaho updated 9/7

Which structures conduct air?

Nasopharynx, oropharynx, larynx, trachea, bronchi + terminal bronchioles.

Which structures perform gas exchange?

Respiratory bronchioles, alveolar ducts + alveoli.

How does pulmonary circulation differ from systemic circulation?

It is a low-pressure system that carries blood to the lungs for gas exchange.

What 3 processes are required for gas exchange?

Ventilation (air reaches alveoli) + diffusion (gases cross membrane) + perfusion (blood reaches alveoli).

What is ventilation?

Movement of air into + out of alveoli.

What is diffusion?

O₂ moves alveoli → blood; CO₂ moves blood → alveoli.

What is perfusion?

Blood flow through pulmonary capillaries.

What are ventilation, perfusion, and diffusion?

Ventilation: air reaches alveoli. Perfusion: blood reaches alveoli. Diffusion: O₂ and CO₂ cross between alveoli and blood

Where does gas exchange occur?

Across the thin alveolar-capillary membrane.

What do type I alveolar cells do?

Allow O₂ and CO₂ to diffuse between alveoli and blood.

What do type II alveolar cells do?

Produce surfactant → decreases surface tension → keeps alveoli open.

What happens when surfactant decreases?

Alveoli collapse (atelectasis) → less gas exchange → hypoxemia.

What 4 factors affect gas diffusion?

↓ Surface area + thick membrane + low alveolar O₂ + poor ventilation + poor perfusion.

How does decreased surface area affect diffusion?

Less area is available for O₂ exchange (example: emphysema).

How does increased membrane thickness affect diffusion?

O₂ cannot cross easily (examples: edema

What determines the amount of O₂ available for diffusion?

Inspired O₂

What is normal room-air FiO₂?

21% O₂.

What is a normal adult tidal volume?

About 400–500 mL per breath.

What is V/Q mismatch?

Ventilation and perfusion do not match → blood receives too little O₂.

What is dead space?

Alveoli receive air but little/no blood flow (example: pulmonary embolism).

What is a shunt?

Blood reaches alveoli that receive little/no air (example: fluid-filled alveoli in pneumonia).

Why is hemoglobin important for oxygenation?

Hemoglobin carries O₂; low hemoglobin can cause tissue hypoxia even when PaO₂ is normal.

2. Hypoxemia

Hypoxia

What is hypoxemia?

Low O₂ in arterial blood (low PaO₂).

What is hypoxia?

Inadequate O₂ delivery or use at the tissue level.

How are hypoxemia and hypoxia different?

Hypoxemia = blood O₂ problem. Hypoxia = tissue O₂ problem.

Can anemia cause hypoxia with a normal PaO₂?

Yes. PaO₂ may be normal

What 3 steps are needed for oxygenation?

Lungs take in O₂ → blood delivers O₂ → cells use O₂.

What causes hypoxemia?

Hypoventilation

What are early signs of hypoxemia?

Restlessness

What are late signs of severe hypoxemia?

Cyanosis

What findings suggest chronic hypoxia?

Polycythemia

Why does chronic hypoxia cause polycythemia?

Kidneys increase RBC production to carry more O₂.

What is hypercapnia?

Too much CO₂ in arterial blood (high PaCO₂).

What causes hypercapnia?

Inadequate ventilation or severe V/Q mismatch.

How does hypercapnia affect ABGs?

↑ PaCO₂ → ↓ pH → respiratory acidosis.

How does hyperventilation affect ABGs?

Too much CO₂ is removed → ↓ PaCO₂ → ↑ pH → respiratory alkalosis.

3. Pulmonary Assessment and Diagnostics

What findings suggest pulmonary disease?

Cough

What should a focused respiratory assessment include?

RR/pattern

What is the difference between SOB and dyspnea?

SOB: patient feels unable to breathe. Dyspnea: difficult breathing with increased work of breathing.

What findings show increased work of breathing?

Accessory-muscle use

Why is abdominal breathing concerning in an adult?

It can show respiratory distress or muscle fatigue.

What accessory muscles may be used during respiratory distress?

Sternocleidomastoid

Why is new confusion important in a pulmonary patient?

It may be an early sign that the brain is not receiving enough O₂.

What is tachypnea?

Abnormally fast breathing.

What is hyperpnea?

Abnormally deep breathing.

What is hypoventilation?

Inadequate ventilation → CO₂ retention → respiratory acidosis.

What is hypopnea?

Abnormally shallow breathing.

What is agonal breathing?

Ineffective gasping with little chest expansion → severe oxygen deprivation.

What does an ABG measure?

PaO₂

What does capnography monitor?

Exhaled CO₂ to evaluate ventilation.

What does a chest x-ray identify?

Infiltrates

What do pulmonary function tests identify?

Whether airflow is obstructed or lung expansion is restricted.

Why are pulmonary function tests avoided during acute illness?

Testing may worsen symptoms and produce inaccurate baseline results.

What does bronchoscopy do?

Views the airways and can collect samples or remove an obstruction.

4. Acute Respiratory Failure and ARDS

What is respiratory failure?

The lungs cannot provide enough O₂ or remove enough CO₂.

Which ABGs suggest respiratory failure in the class notes?

PaO₂ ≤60 mm Hg and/or PaCO₂ >50 mm Hg with failed gas exchange.

What causes hypoxemic respiratory failure?

V/Q mismatch, shunting, or poor diffusion → low PaO₂.

What causes hypercapnic respiratory failure?

Inadequate ventilation → high PaCO₂, low PaO₂, and respiratory acidosis.

What conditions can cause acute respiratory failure?

Pneumonia, atelectasis, obesity, asthma, pulmonary embolism, or ARDS.

What findings suggest worsening respiratory failure?

Increased work of breathing, falling SpO₂, confusion, cyanosis, fatigue, or rising PaCO₂.

Why is new drowsiness dangerous in respiratory failure?

Rising CO₂ may be depressing the brain → respiratory arrest may follow.

What is ARDS?

Severe inflammatory lung injury → leaky capillaries → fluid-filled alveoli → severe hypoxemia.

What commonly causes ARDS?

Sepsis, aspiration, major trauma, pancreatitis, fat embolism, or drugs/toxins.

What cellular changes occur in ARDS?

Alveolar-capillary injury → fluid enters alveoli → surfactant stops working → alveoli collapse → hyaline membranes form.

Why is ARDS hypoxemia difficult to correct?

Blood passes fluid-filled or collapsed alveoli → severe shunting.

What findings suggest ARDS?

Severe dyspnea, tachypnea, diffuse crackles, cyanosis, and hypoxemia that does not improve easily with O₂.

How is ARDS severity measured?

PaO₂/FiO₂ ratio; a lower ratio means worse oxygenation.

5. Comparing Lower Respiratory Disorders

How do obstructive and restrictive diseases differ?

Obstructive: hard to get air out. Restrictive: hard to expand lungs.

What findings suggest obstructive disease?

Wheezing, prolonged expiration, cough, mucus, and air trapping.

What findings suggest restrictive lung disease?

Progressive dyspnea, rapid shallow breathing, dry cough, clubbing, and little/no wheezing.

What happens in emphysema?

Alveolar walls and elastic recoil are lost → air trapping and less diffusion area.

Why does emphysema cause a barrel chest?

Chronic air trapping overexpands the lungs.

What are the main causes of emphysema?

Smoking and alpha₁-antitrypsin deficiency.

What happens in chronic bronchitis?

Chronic inflammation and excess mucus narrow the airways.

What defines chronic bronchitis?

Productive cough for at least 3 months in 2 consecutive years.

What is bronchiectasis?

Repeated infection and inflammation destroy airway walls → permanent bronchial dilation.

What findings suggest bronchiectasis?

Recurrent infections, large amounts of foul-smelling sputum, and hemoptysis.

6. Asthma

What is asthma?

Chronic airway inflammation causing reversible bronchospasm, swelling, mucus, and airflow obstruction.

What is the strongest asthma risk factor?

Genetic tendency to develop an IgE response to allergens.

What can trigger asthma?

Allergens, smoke, infection, exercise, weather changes, stress, pollution, medications, or GERD.

What happens during an asthma attack?

Inflammatory mediators cause bronchospasm + swelling + mucus → narrowed airways → difficult expiration.

What findings suggest asthma?

Episodic wheezing, cough, chest tightness, tachypnea, and prolonged expiration.

Why can asthma worsen at night?

Lower cortisol/epinephrine and increased bronchoconstrictor activity narrow the airways.

What is the early ABG pattern in asthma?

↓ PaO₂ + ↓ PaCO₂ + ↑ pH.

Why is a normal or rising PaCO₂ dangerous in severe asthma?

Ventilation is failing → respiratory acidosis + possible respiratory failure.

What is airway remodeling?

Repeated inflammation permanently thickens the airways → obstruction becomes less reversible.

How is asthma diagnosed?

History plus pulmonary function tests showing reversible airflow obstruction.

What is the treatment goal for asthma?

Avoid triggers, control inflammation, and reverse bronchospasm.

What is status asthmaticus?

Severe bronchospasm that continues despite usual treatment.

7. Pneumonia

What is pneumonia?

Infection or inflammation causes fluid and cells to collect in alveoli and bronchioles.

Who is at risk for pneumonia?

Older adults, smokers, chronically ill or malnourished patients, and patients with aspiration or intubation.

What happens in pneumonia?

Inflammation → capillary leak → WBCs, RBCs, fibrin, and fluid fill alveoli → consolidation.

Why does pneumonia cause hypoxemia?

Blood reaches fluid-filled alveoli that cannot receive enough air → shunting/V/Q mismatch.

What findings suggest pneumonia?

Fever, chills, cough, sputum, tachypnea, tachycardia, dyspnea, pleuritic pain, and decreased breath sounds.