Day 4 — Respiratory: oxygenation, ventilation, gas exchange

What is ventilation?

Movement of air in and out of the lungs.

What is oxygenation?

Getting oxygen into the blood.

What is gas exchange?

Oxygen moves from the alveoli into the blood, and carbon dioxide moves from the blood into the alveoli.

Where does gas exchange happen?

In the alveoli.

What direction does oxygen move during gas exchange?

From the alveoli into the blood.

What direction does carbon dioxide move during gas exchange?

From the blood into the alveoli to be exhaled.

What is hypoxemia?

Low oxygen in the blood.

What is hypoxia?

Low oxygen in the tissues.

What does SpO₂ help assess?

Oxygenation.

What does high CO₂ suggest?

Poor ventilation or poor CO₂ removal.

Why can poor oxygenation cause confusion?

The brain is not getting enough oxygen.

Why can poor oxygenation cause tachycardia?

The heart beats faster to deliver more oxygen to tissues.

Why can poor oxygenation cause restlessness?

Restlessness can be an early sign that the brain is not getting enough oxygen.

What lung sound is common with narrowed airways?

Wheezing.

What lung sound is common with fluid in the lungs?

Crackles.

What does diminished breath sound suggest?

Poor air movement.

What is a common sign of increased work of breathing?

Accessory muscle use.

How does pneumonia impair gas exchange?

Fluid, pus, and inflammation fill the alveoli, making oxygen movement harder.

How does asthma affect ventilation?

Bronchoconstriction and inflammation narrow the airways, making air movement harder.

How does COPD affect gas exchange?

Chronic airway and alveolar damage causes air trapping and poor oxygen/carbon dioxide exchange.

How does pulmonary embolism impair oxygenation?

A clot blocks blood flow to part of the lung, so gas exchange is reduced.

What should the nurse assess first in a respiratory problem?

Airway and breathing.

Why is high Fowler’s position helpful?

It improves lung expansion and makes breathing easier.

Pneumonia pattern

Infection/inflammation in the alveoli causes fluid or pus buildup, which impairs gas exchange and can lower SpO₂.

Why does pneumonia cause low SpO₂?

Fluid, pus, and inflammation in the alveoli make it harder for oxygen to move into the blood.

Common signs of pneumonia

Fever, cough, crackles, increased work of breathing, low SpO₂, fatigue.

What lung sound is common with pneumonia?

Crackles.

Why are crackles heard in pneumonia?

Fluid or secretions are present in the alveoli or small airways.

Priority concern in pneumonia

Low SpO₂ with increased work of breathing.

COPD pattern

Chronic airway and alveolar damage causes air trapping, poor gas exchange, and possible CO₂ retention.

Why can COPD cause CO₂ retention?

The patient has poor ventilation and cannot blow off carbon dioxide effectively.

Common signs of COPD

Dyspnea, wheezing, barrel chest, chronic cough, low SpO₂, CO₂ retention.

What does drowsiness in COPD suggest?

Possible CO₂ retention from poor ventilation.

Why does COPD impair gas exchange?

Damaged alveoli and air trapping reduce effective oxygen and carbon dioxide exchange.

Asthma pattern

Airway inflammation and bronchoconstriction narrow the airways, causing wheezing and difficulty moving air.

Why does asthma cause wheezing?

Air moves through narrowed airways.

What happens during an asthma attack?

Airways become inflamed, swollen, and constricted, making ventilation difficult.

Priority concern in asthma

Severe respiratory distress, inability to speak full sentences, very diminished breath sounds, or low SpO₂.

Why are very diminished breath sounds concerning in asthma?

Air movement may be severely decreased, which can mean worsening respiratory failure.

Pulmonary embolism pattern

A clot blocks blood flow to part of the lung, reducing gas exchange and causing sudden dyspnea, chest pain, tachycardia, and low SpO₂.

What is the main problem in pulmonary embolism?

Blood flow to part of the lung is blocked by a clot.

Why can PE cause sudden low SpO₂?

Air may reach the alveoli, but blood flow is blocked, so gas exchange is reduced.

Common signs of pulmonary embolism

Sudden shortness of breath, sharp chest pain, tachycardia, low SpO₂, anxiety, possible hemoptysis.

What does ventilation-perfusion mismatch mean?

Air and blood flow are not matching correctly in the lungs.

What happens in PE with ventilation and perfusion?

Ventilation may still occur, but perfusion is blocked by a clot.

What condition is linked to fluid or pus in the alveoli?

Pneumonia.

What condition is linked to bronchoconstriction?

Asthma.

What condition is linked to air trapping and CO₂ retention?

COPD.

What condition is linked to sudden dyspnea, chest pain, tachycardia, and low SpO₂?

Pulmonary embolism.

Why can respiratory problems cause confusion?

The brain may not be getting enough oxygen, or CO₂ may be building up.

Why can respiratory problems cause tachycardia?

The heart beats faster to deliver more oxygen to tissues.

Why is increased work of breathing concerning?

The patient is using extra effort to breathe and may tire out.

What are signs of impaired oxygenation?

Low SpO₂, restlessness, confusion, tachycardia, cyanosis, shortness of breath.

What are signs of impaired ventilation?

Slow or shallow breathing, high CO₂, drowsiness, confusion, poor air movement.

Which respiratory patient should be assessed first?

The patient with sudden shortness of breath, chest pain, SpO₂ 84%, or severe work of breathing.

Pneumonia chain

Infection/inflammation in alveoli → fluid/pus in alveoli → impaired gas exchange → low SpO₂/crackles.

Asthma chain

Airway inflammation + bronchoconstriction → narrowed airways → poor ventilation → wheezing/shortness of breath.

COPD chain

Chronic airway/alveolar damage → air trapping → CO₂ retention/poor gas exchange → dyspnea and low SpO₂.

Pulmonary embolism chain

Clot blocks blood flow in lung → perfusion is blocked → gas exchange decreases → sudden dyspnea/low SpO₂.