Need for O2 study guide

Circulatory Hypoxia

The heart cannot pump enough blood to move oxygen around the body.

Causes: Heart failure or severe shock

Anemic Hypoxia

The blood doesn't have enough red blood cells (or hemoglobin) to carry oxygen.

Causes: Anemia or carbon monoxide poisoning

Histotoxic Hypoxia

Oxygen reaches the cells, but the cells are damaged and cannot use it.

Causes: Cyanide poisoning or severe systemic infection (sepsis).

What is the “normal” PaO2 at sea level? What is generally the lowest PaO2

we will accept for people at sea level?

• Normal level at sea level: 80-100

• Lowest acceptable level: About 55-60. After age 60, normal baseline levels drop by 1 mmHg for every year of age

Define “refractory hypoxemia” – look at the definition with the * on the

slide! What does it mean for healthcare providers?

• Definition: Extremely low blood oxygen that does not go up, even when you give the patient high concentrations of extra oxygen.
  
  

• What it means for medical teams: It causes (shunting) and need special pressure machines (like PEEP or CPAP)

Define “occult hypoxemia”. Why is this a problem?

• Definition: Hidden low blood oxygen. The finger clip sensor (pulse oximeter) reads a safe level 92-96, but actual blood tests reveal dangerous oxygen levels (under 88

• Why it's a problem: Doctors might think a patient is fine when they are actually dangerously low on oxygen. It happens twice as often in People of Color due to how light sensors interact with skin pigmentation

What is the “cardinal” sign of hypoxemia?

Tachycardia

What is the mechanism of cyanosis? Why is it important?

• How it works: Skin or lips turn blue when blood lacks oxygen (5 g/dL or more of unoxygenated hemoglobin).

• Why it's tricky: You can be blue without low oxygen (like having too many red blood cells), or dangerously low on oxygen without turning blue (like severe anemia).

Is “acrocyanosis” acceptable in a newborn?

Yes, this is normal and safe for a newborn baby unless it’s been over 10 minutes since birth

What does pulse oximetry “see”? Does the saturation disp

They shine two types of light through the skin to estimate oxygen in the blood. They do not give a perfect, 100$ guaranteed measure because other factors (like carbon monoxide) can trick the light sensors.

What are the sources of pulse oximetry errors?

• Cold hands/poor blood flow

• Too much movement

• nail polish

• Bright room lights

• Carbon monoxide poisoning

What are the 5 hazards of O2 therapy that we discussed?

• Oxygen induced hypoventilation (in chronic lung disease)

• Oxygen toxicity (from breathing too much pure oxygen)

• Eye damage / blindness (in premature infants)

• Collapsed lung sacs (absorption atelectasis)

• Fire hazard

Which one is most likely to affect a patient with COPD?

Oxygen-induced hypoventilation (their brain may tell them to breathe less if they get too much oxygen)

Which one is most likely to affect a premature infant?

Retinopathy of Prematurity (ROP), which can cause vision loss or blindness.

Which one is most likely to affect critically ill patients requiring high

FIO2’s for extended periods of time?

(Oxygen Toxicity), caused by chemical buildup (free radicals) damaging lung cells.

Which hazard of breathing 100% O2 is likely made worse is the

patient is heavily sedated or is in a lot of pain (likely post-op)?

Absorption Atelectasis (shallow breathing allows air sacs to collapse as high-concentration oxygen is quickly absorbed).