Oxygenation and Gas Exchange

anoxia

cessation of oxygenation leading to no oxygen in the body

cyanosis

a bluish or purplish discoloration of the skin and mucous membranes resulting from an inadequate amount of oxygen in the blood

diffusion

diffusion is the passive movement of particles (like molecules, ions, or gases) from an area of higher concentration to an area of lower concentration

dyspnea

the subjective sensation of difficulty breathing or shortness of breath

hemoptysis

the coughing up of blood from the respiratory tract

hypoxia

insufficient oxygenation in the tissues

hypoxemia

an abnormally low concentration of oxygen in the arterial blood

ischemia

an inadequate blood supply to an organ or part of the body, especially the heart muscles

oxygenation

the process of providing oxygen to all the cells of the body, via ventilation, diffusion, perfusion, oxygen-carrying cells, and cellular utilization

perfusion

passage of fluid (especially blood) through the circulatory system or lymphatic system to an organ or tissue, supplying oxygen and nutrients and removing waste products

retractions

the inward pulling or sinking of the skin between or around the bones of the chest wall during inspiration, indicating increased work of breathing

pulmonary ventilation

pulmonary ventilation is defined as the process of air flowing into the lungs (inspiration) and out of the lungs (expiration), the mechanical act of breathing

alveolar ventilation

the volume of air that actually reaches the alveoli and is available for gas exchange with the blood per unit of time

What is oxygenation?

The process of delivering oxygen to the tissues via the lungs and bloodstream.

What are the three components of gas exchange?

Ventilation, diffusion, and perfusion.

What is ventilation?

The movement of air in and out of the lungs.

What is perfusion?

The movement of blood through the pulmonary capillaries.

What is diffusion?

The transfer of gases across the alveolar-capillary membrane.

Where does gas exchange occur?

In the alveoli of the lungs.

What muscle is the primary driver of inspiration?

The diaphragm.

What are accessory muscles of respiration?

Sternocleidomastoid, scalenes, intercostals.

What does surfactant do?

Lowers surface tension and prevents alveolar collapse.

What cells produce surfactant?

Type II alveolar cells.

What are early signs of hypoxia?

Restlessness, anxiety, tachypnea, tachycardia.

What are late signs of hypoxia?

Cyanosis, bradypnea, bradycardia, confusion.

What is hypoxemia?

Low oxygen levels in the blood (PaO2 < 80 mmHg).

What is hypoxia?

Low oxygen levels in the tissues.

What lab test measures oxygen in the blood?

Arterial blood gas (ABG).

Normal PaO2 range?

80–100 mmHg.

Normal PaCO2 range?

35–45 mmHg.

Normal HCO3 range?

22–26 mEq/L.

Normal blood pH?

7.35–7.45.

Normal SpO2 range?

95–100%.

What causes hypercapnia?

Hypoventilation, respiratory failure, CNS depression.

What are signs of hypercapnia?

Drowsiness, headache, confusion, flushed skin.

What is the function of the upper airway?

Warm, humidify, and filter inspired air.

What is the function of the lower airway?

Conduct air to the lungs and produce surfactant.

What sound is heard in narrowed airways?

Wheezing.

What sound is heard with fluid in alveoli?

Crackles.

What condition involves alveolar collapse?

Atelectasis.

What does the tripod position indicate?

Severe respiratory distress.

What is orthopnea?

Difficulty breathing while lying flat.

What is dyspnea?

Difficulty breathing or shortness of breath.

What is stridor?

High-pitched inspiratory sound from upper airway obstruction.

What is hemoptysis?

Coughing up blood.

What does clubbing indicate?

Chronic hypoxia.

What is a nasal cannula’s flow rate?

1–6 L/min.

FiO2 range of nasal cannula?

24–45%.

When should you humidify nasal cannula oxygen?

At flow rates >4 L/min.

Flow rate of simple face mask?

6–10 L/min.

FiO2 range of simple face mask?

40–60%.

Flow rate of partial rebreather?

6–10 L/min.

FiO2 range of partial rebreather?

35–60%.

Flow rate of non-rebreather?

10–15 L/min.

FiO2 range of non-rebreather?

60–100%.

What is the most precise oxygen delivery device?

Venturi mask.

Who benefits from a Venturi mask?

Patients with COPD needing exact oxygen levels.

What is a face tent used for?

Facial trauma or burns needing humidified O2.

What causes crackles in lungs?

Air moving through fluid-filled alveoli.

What is the best initial intervention for low oxygenation?

Raise the head of the bed.

What does an SpO2 below 90% indicate?

Inadequate oxygenation—requires intervention.

What respiratory changes are seen in infants?

Faster rate, nose breathing, smaller airways.

When is surfactant produced in utero?

Between 34–36 weeks.

What puts neonates at risk for RDS?

Prematurity (before surfactant production).

What causes grunting in infants?

Attempt to keep alveoli open—respiratory distress.

Signs of increased work of breathing in peds?

Nasal flaring, retractions, grunting, head bobbing.

What happens to lung elasticity with aging?

It decreases.

What happens to alveolar surface area in elderly?

It decreases.

What happens to immune response with age?

It weakens.

What is a pulse oximeter used for?

Non-invasive monitoring of oxygen saturation.

What interferes with SpO2 accuracy?

Cold extremities, nail polish, movement, low perfusion.

When do you use a bag-valve mask (BVM)?

When patient is apneic or has no respiratory effort.

What is the oxygen toxicity risk in COPD?

It can suppress the respiratory drive.

What FiO2 does a Venturi mask deliver?

24–60%, precisely regulated.

What are central chemoreceptors sensitive to?

Changes in CO2 and pH in the blood.

What triggers breathing in healthy individuals?

Elevated CO2 levels.

What triggers breathing in COPD patients?

Low O2 levels (hypoxic drive).

What is paradoxical breathing?

Chest and abdomen move in opposite directions—bad sign.

What is pursed-lip breathing for?

Helps with air trapping in COPD and promotes exhalation.

What does a pulse ox of 85% require?

Escalation to a Venturi mask or non-rebreather.

What is the best position for oxygenation?

High Fowler’s or tripod.

What causes dead space ventilation?

Alveoli ventilated but not perfused (e.g., PE).

What is a shunt?

Blood perfusing non-ventilated alveoli (e.g., pneumonia).

What test measures lung volumes and capacity?

Pulmonary function test (PFT).

What test can detect V/Q mismatch?

V/Q scan (ventilation/perfusion scan).

What is the first sign of respiratory distress in a child?

Restlessness or irritability.

What device is used for patients who eat/talk often?

Nasal cannula.

What is the nurse's priority for a collapsed reservoir bag?

Increase the oxygen flow rate.

What diagnostic value indicates respiratory acidosis?

Low pH + high PaCO2.

What is orthopnea commonly seen in?

Heart failure and COPD.

What is the oxygen source for a concentrator?

Room air compressed and filtered.

What is a contraindication for face masks?

Claustrophobia, eating, facial trauma.

What vital signs indicate worsening hypoxia?

Falling O2 sat, rising HR, rising RR.

What is cyanosis?

Bluish discoloration of skin and mucosa from low O2.

What are normal breath sounds?

Vesicular, bronchial, and bronchovesicular.

What are adventitious breath sounds?

Crackles, wheezes, rhonchi, stridor.

What condition causes frothy pink sputum?

Pulmonary edema.

What condition causes rust-colored sputum?

Pneumococcal pneumonia.

What does yellow-green sputum suggest?

Bacterial infection.

What sound is heard in asthma?

Wheezing on expiration.