NCLEX-RN Study Guide

NCLEX Respiratory Questions and ABG Guide (2026)

November 2, 2026 · 5 min read

Short answer. Respiratory NCLEX questions test your ability to read an arterial blood gas and act on it, and to spot a client who is tiring before they arrest. Oxygen is a drug with a target range, not a default.

What the 2026 NCLEX tests in this area

Physiological Adaptation: asthma, COPD, pneumonia, pulmonary embolism
Reduction of Risk Potential: ABG interpretation, chest tubes, suction, tracheostomy care

Key facts to know

Normal arterial pH	7.35 to 7.45
Normal PaCO2	35 to 45 mmHg
Normal bicarbonate	22 to 26 mEq/L
Normal PaO2	80 to 100 mmHg
Water seal chamber	Tidaling with breathing is expected. Continuous bubbling means an air leak
Target SpO2 for most adults on oxygen	94 to 98 percent, or the range prescribed for a COPD client

Practice question from this chapter

A client with respiratory failure is receiving mechanical ventilation. The high-pressure alarm sounds and the oxygen saturation is 88%. Which action should the nurse implement first?

Assess the client for coughing, secretions, or biting the tube
Suction the endotracheal tube
Disconnect the ventilator and use a manual resuscitation bag
Call respiratory therapy to evaluate the ventilator

Show answer and rationale

Correct answer: A. Assess the client for coughing, secretions, or biting the tube

Assessing the client for coughing, secretions, or biting the tube is correct because a high-pressure alarm indicates increased airway resistance, and the first step is to identify the cause at the client bedside. Suctioning fails because it is done only after assessment shows secretions are the cause. Disconnecting the ventilator and bagging fails because it is reserved for failure to ventilate, not a high-pressure alarm without assessment. Calling respiratory therapy fails because the nurse must assess the client first.

Second practice question

A client being weaned from mechanical ventilation has a respiratory rate of 32 breaths/min, an oxygen saturation of 90% on 40% oxygen, and is using accessory muscles. Which action should the nurse anticipate?

Continue the weaning trial for another hour
Increase the pressure support setting
Schedule the client for a tracheostomy
Return the client to full ventilator support

Show answer and rationale

Correct answer: D. Return the client to full ventilator support

Tachypnea, borderline oxygen saturation, and accessory muscle use indicate the client is not tolerating the weaning trial, so the trial should be stopped and full ventilator support resumed. Continuing the trial or adjusting settings independently risks fatigue and respiratory failure.

The four step ABG method

Look at pH first and name the primary disorder: below 7.35 is acidemia, above 7.45 is alkalemia. Then look at PaCO2. If it moves opposite to pH, the problem is respiratory. If bicarbonate moves in the same direction as pH, the problem is metabolic. Finally ask whether the body is compensating, because compensation changes the treatment priority.

Respiratory acidosis with a rising PaCO2 in a client who is sleepy is a ventilation problem, not an oxygen problem. Increasing the nasal cannula does not fix hypoventilation. That distinction is worth several items on its own.

Chest tubes and drains

Never clamp a chest tube to stop bubbling as a first response. Bubbling in the water seal means air is escaping the pleural space, which is the tube doing its job. Clamping can convert a simple leak into a tension pneumothorax. If the tube disconnects, the priority is restoring the seal, not documenting the event.

Work the oxygen delivery ladder

Know the escalation order and the reason for each step. Nasal cannula for mild hypoxaemia, a simple face mask for moderate, a venturi mask when you need a precise fraction of inspired oxygen, a non rebreather for severe hypoxaemia, and high flow or non invasive ventilation when the work of breathing is the problem rather than the oxygen level alone.

The clinical judgement item hides in that last distinction. A client with a normal saturation who is using accessory muscles and has a rising carbon dioxide level is tiring, and no amount of nasal cannula fixes that. Escalate the support and call for help.

Where the marks leak

Candidates lose respiratory items by choosing to reassess when the client is already deteriorating, and by clamping a chest tube to stop bubbling. Both feel like reasonable nursing and both delay the intervention that matters.

A second leak is forgetting that oxygen is titrated to a target range. The order, not the habit, sets the target, and for a client with chronic carbon dioxide retention that target is often lower than you expect.

Frequently asked questions

What is the fastest way to interpret ABGs on the NCLEX?

Name the pH, then compare PaCO2 and bicarbonate to it. The value moving in the opposite direction to pH is the cause. Compensating values move with pH.

Is a bubbling chest tube bad?

Not automatically. Tidaling and intermittent bubbling in the water seal are expected. Continuous bubbling suggests an air leak that needs investigation, but clamping is not the answer.

How much oxygen should a COPD client receive?

Titrate to the prescribed target, often 88 to 92 percent in a client with chronic CO2 retention. The exam still expects you to treat hypoxia rather than withhold oxygen.

What respiratory topic is most missed?

Recognising fatigue. A rising PaCO2 with a normal oxygen saturation means the client is failing to ventilate, and that is an escalation, not a reason to wait.

How do I tell respiratory acidosis from metabolic acidosis quickly?

Look at the carbon dioxide. A low pH with a high carbon dioxide is respiratory. A low pH with a low bicarbonate is metabolic. If both move toward acidosis, the client has a mixed disorder.

What is the first sign a respiratory client is tiring?

A rising respiratory rate with shallow breathing, accessory muscle use and a change in mental status. Oxygen saturation can still look acceptable at that point, which is why the trend matters more than the number.

Practise this chapter with rationales

NCLEXDeck gives you practice questions for every body system, with a rationale for the correct answer and for each distractor. Start on the free tier, no card required.

Start free