NUR1112 · Fundamental Skills and Knowledge for Nursing and Midwifery Practice 1
The Respiratory System & Focused Respiratory Assessment
Week 8 covers the respiratory system (airways, ventilation, gas exchange and transport, and the respiratory contribution to plasma pH) and the focused respiratory assessment — inspection, auscultation, respiratory rate and oxygen saturation, and recognising respiratory deterioration. Oxygen therapy is titrated to a saturation target, and matching a delivery device to the degree of hypoxia is a recurring clinical-reasoning task.
What this chapter covers
- 01Airways, ventilation and gas exchange; gas transport and the respiratory contribution to plasma pH
- 02CO₂ transported mostly as bicarbonate ion (HCO₃⁻) in plasma; rising blood CO₂ is the main drive to breathe
- 03Boyle's-law mechanics of ventilation: thoracic volume ↑ → intrapulmonary pressure ↓ → air flows in
- 04Obstructive vs restrictive disorders; asthma as an obstructive disease (wheeze, air trapping)
- 05Breath sounds: wheeze (obstructive/asthma) vs crackles (e.g. lobar pneumonia)
- 06Focused respiratory assessment: inspection, auscultation, respiratory rate, SpO₂, accessory-muscle use
- 07Oxygen therapy titrated to a saturation target; matching delivery device and flow to hypoxia severity
Titrating oxygen to a saturation target
- +1(a) SpO₂ 96% is above the >94% target, so oxygenation currently meets the goal — continue therapy and monitor the wheeze and respiratory rate.
- +1(b) SpO₂ 89% is well below the >94% target — this is inadequate oxygenation. Escalate: increase oxygen/adjust the device and seek senior review, and reassess.
- +1(c) SpO₂ 92% is below the target and paired with a rising respiratory rate (24) and increased work of breathing — escalate, increase support and reassess frequently.
Key terms
- Gas exchange
- The movement of oxygen from alveoli into blood and carbon dioxide from blood into alveoli, at the respiratory membrane; the core function of the respiratory zone.
- Bicarbonate (HCO₃⁻)
- The form in which most carbon dioxide is transported in the plasma after entering red blood cells; central to the respiratory contribution to plasma pH regulation.
- Obstructive respiratory disease
- A condition that narrows the airways and increases expiratory resistance (e.g. asthma), causing air trapping and a wheeze — contrasted with restrictive disorders that limit lung expansion.
- Wheeze vs crackles
- Wheeze is a whistling sound of narrowed airways (obstructive disease such as asthma); crackles are discontinuous popping sounds heard, for example, over lobar pneumonia.
- Oxygen saturation target
- The SpO₂ level oxygen therapy is titrated to maintain (in the worked case, above 94%); saturations below the target prompt escalation.
- Accessory-muscle use
- Recruitment of neck and chest muscles to assist breathing, a sign of increased work of breathing graded from mild to moderate during respiratory assessment.
The Respiratory System & Focused Respiratory Assessment FAQ
Is asthma an obstructive or restrictive disease?
Asthma is an obstructive respiratory disease: the airways narrow, expiratory resistance rises and air is trapped, producing a wheeze. Restrictive disorders, by contrast, limit lung expansion. Being able to place a condition on the obstructive-versus-restrictive axis and predict the breath sounds and work of breathing is a common assessment point.
How is carbon dioxide transported and why does it matter for pH?
Most CO₂ is carried in the plasma as bicarbonate ion (HCO₃⁻) after entering red blood cells. Because CO₂ and bicarbonate are linked to blood pH, the respiratory system helps regulate plasma pH — and rising blood CO₂ is the main drive to breathe. This links the bioscience and assessment threads: changes in ventilation change pH.
How do I decide when to escalate a respiratory assessment?
Read SpO₂ against the ordered target and interpret it alongside respiratory rate and work of breathing (accessory-muscle use). A saturation below the target — especially with a rising respiratory rate — is inadequate oxygenation and should be escalated. Confirm the specific escalation triggers on your unit's observation chart rather than assuming a threshold.
Can Sia help me with respiratory assessment?
Yes — Sia can generate respiratory datasets for you to triage, explain the obstructive-versus-restrictive distinction, or walk through gas exchange and CO₂ transport step by step. It teaches the method and checks your reasoning; it does not complete a graded assessment for you, and academic-integrity rules apply.
Exam move
Tie the two threads together: the bioscience (gas exchange, CO₂ as bicarbonate, Boyle's-law mechanics, the CO₂ drive to breathe) explains the clinical findings you assess (SpO₂, respiratory rate, breath sounds, work of breathing). Practise triaging a respiratory dataset against a saturation target and deciding on escalation, and be able to place a condition as obstructive or restrictive and predict its signs. Ask Sia to feed you cases mixing normal and deteriorating observations.
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