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Nursing Field Notes / Respiratory · Med-Surg Course

Acute Respiratory Failure 🆘

Type I vs Type II · the numbers · when to call

NG-396 Respiratory ADHD-friendly visual edition

Respiratory failure is not a disease, it is a number. The lungs are failing at one of two jobs: getting oxygen in, or getting carbon dioxide out. Which one tells you what to do.

Type I — oxygenationPaO₂ < 60. The problem is getting O₂ IN
Type II — ventilationPaCO₂ > 50 with pH < 7.35. CO₂ will not come OUT
The earliest signRestlessness and confusion — not the saturation
The ruleTreat the cause, support the failing job

🧨 What starts it

Two gauges: oxygen coming in with the arrow below sixty, which is type one failure, and carbon dioxide going out with the arrow above fifty and a falling pH, which is type two. Under each, the causes and what it needs.
Respiratory failure is a number, not a disease. Which of the two jobs has failed decides what you do. Swipe it sideways if it is cut off, or tap to open it full size.
Two failures, two numbers
  • Type I — hypoxemic. PaO₂ under 60 mmHg on room air. Blood is passing alveoli that are collapsed, flooded or blocked. Causes: pneumonia, ARDS, pulmonary edema, PE, atelectasis.
  • Type II — hypercapnic. PaCO₂ over 50 mmHg with a pH under 7.35. She is not moving enough air. Causes: COPD exacerbation, opioid overdose, Guillain-Barré, myasthenic crisis, chest trauma, severe obesity.
  • Many patients have both. A COPD exacerbation is the classic mixed picture.
Think about it as a chain
  • Drive — will she breathe? (opioids, head injury, stroke)
  • Pump — can she breathe? (weak muscles, flail chest, kyphoscoliosis)
  • Pipes — is air getting through? (asthma, COPD, obstruction)
  • Membrane — does it exchange? (pneumonia, ARDS, edema, PE)

Locate the break in the chain and the treatment follows.

Why COPD is different

Someone with chronic CO₂ retention lives at a high PaCO₂. Compare against her baseline, not the textbook. A pH under 7.35 is what says this is acute — the CO₂ number alone does not.

🔎 What you will see

What you see, in the order you see it
  • Restlessness, anxiety, confusion. The brain notices first. This is the earliest sign and it is the one that gets missed.
  • Tachypnoea, tachycardia, rising blood pressure.
  • Accessory muscles, nasal flaring, tripod position.
  • Then: lethargy, a bounding pulse, headache, flushed skin — that combination is CO₂ retention.
  • Late: bradycardia, falling blood pressure, cyanosis, silent chest. Arrest is next.
What the ABG tells you
  • Low PaO₂ alone → Type I. Give oxygen, find the cause.
  • High PaCO₂ with a low pH → Type II. She needs ventilation, not just more oxygen.
  • High PaCO₂ with a normal pH → chronic and compensated. Not the emergency.
  • A normal PaCO₂ in someone working this hard is a red flag — she should be blowing it off. She is tiring.
The single most useful question

Is she working harder or giving up? A quiet chest, a slowing rate and a falling level of consciousness in a struggling patient mean arrest is minutes away.

🩺 What you do

What you do
  1. Position upright. High Fowler’s or tripod. Free.
  2. Oxygen — titrate. In COPD aim 88 to 92%, not 100%.
  3. Call for help. Rapid response.
  4. ABG, continuous monitoring, IV access.
  5. Treat the cause: bronchodilators, antibiotics, naloxone, diuretics — whichever the chain points to.
  6. Escalate support: BiPAP for Type II if she is awake and protecting her airway; intubation if she is not.
BiPAP or intubate?
  • BiPAP works for COPD exacerbation and cardiogenic pulmonary edema in an alert, cooperative patient who can protect her airway.
  • BiPAP is wrong if she is unconscious, vomiting, has facial trauma, or cannot clear secretions.
  • Falling level of consciousness, exhaustion, or a pH that keeps dropping on BiPAP → intubate.
The oxygen rule people get wrong

High-flow oxygen in a chronic CO₂ retainer can worsen hypercapnia — but hypoxia kills faster than hypercapnia. If she is severely hypoxic you give the oxygen she needs and prepare to support ventilation. You do not withhold oxygen from a dying patient because of a number.

⚡ Quick recall

Type I — oxygenationPaO₂ < 60. The problem is getting O₂ IN
Type II — ventilationPaCO₂ > 50 with pH < 7.35. CO₂ will not come OUT
The earliest signRestlessness and confusion — not the saturation
The ruleTreat the cause, support the failing job
Give the numbers for Type I and Type II.
Type I: PaO2 under 60. Type II: PaCO2 over 50 with a pH under 7.35.
What is the earliest sign of respiratory failure?
A change in mental status — restlessness, anxiety, confusion. Before the saturation moves.
A struggling patient has a normal PaCO2. Good or bad?
Bad. She should be blowing it off. A normal number here means she is tiring.
Who is BiPAP for, and who is it not for?
For an alert COPD or pulmonary edema patient who can protect her airway. Not for someone unconscious, vomiting or unable to clear secretions.
Target saturation in COPD?
88 to 92 percent, not 100.