During weaning from mechanical ventilation, which sign indicates that the patient is not tolerating the trial?

GMCH Nursing Officer-2025

Medical & Surgical Nursing

Medium

Appeared in: GMCH Nursing Officer-2025

Explanation

Use of accessory muscles (like the sternocleidomastoid and scalenes) and paradoxical abdominal movement (abdomen moves inward during inspiration) are classic signs of significant respiratory distress.
These signs indicate that the diaphragm, the primary muscle of respiration, is fatigued, and the patient is expending a large amount of energy to breathe.
This increased work of breathing is unsustainable and is a clear indicator that the patient is failing the spontaneous breathing trial and is not ready for extubation.

Option A: A respiratory rate of 18 breaths per minute is within the normal range for an adult (12-20/min) and is a sign of stable, comfortable breathing, indicating tolerance to the weaning trial.
Option B: An SpO₂ of 96% is a normal oxygen saturation level, indicating adequate gas exchange and oxygenation. This is a sign of success, not failure.
Option D: A tidal volume of 450 mL is generally considered adequate for an average-sized adult (around 6-8 mL/kg ideal body weight). It suggests the patient can generate a sufficient breath volume on their own.

Visual 1: Diagram - Illustration of the accessory muscles of respiration (sternocleidomastoid, scalenes, intercostals) to help learners identify them.
Visual 2: Animation - A short animation contrasting normal diaphragmatic breathing with paradoxical abdominal movement to clarify this key sign of respiratory distress.

Clinical Relevance

Nursing practice connection: Use the key finding related to Assessment of patient tolerance during weaning from mechanical ventilation to guide bedside assessment, documentation, and the next nursing action.
A nurse's primary role during a weaning trial is vigilant monitoring for signs of intolerance. Promptly identifying failure and stopping the trial is crucial to prevent severe respiratory muscle fatigue, which can prolong the need for mechanical ventilation.
Failure to recognize these signs can lead to respiratory arrest. The nurse must be prepared to immediately return the patient to full ventilator support if signs of intolerance appear.
What if? If the patient showed a respiratory rate of 36/min and an SpO₂ of 89%, even without obvious accessory muscle use, these objective criteria alone would be sufficient to declare the weaning trial a failure and stop it.

How to Approach the Question

First, understand the question is asking for a sign of failure or intolerance during weaning from mechanical ventilation.
Next, evaluate each option to determine if it represents a normal/stable finding or an abnormal/distress finding.
Recall the normal ranges for respiratory parameters: Respiratory Rate (12-20/min), SpO₂ (greater than 92-95%), and adequate Tidal Volume (5-8 mL/kg).
Analyze Option A (RR 18/min): This is normal. It indicates tolerance.
Analyze Option B (SpO₂ 96%): This is normal. It indicates tolerance.
Analyze Option C (Accessory muscle use & paradoxical movement): These are hallmark signs of increased work of breathing and respiratory distress. This indicates intolerance.

Concept Tested & Keywords

Concept Tested: Assessment of patient tolerance during weaning from mechanical ventilation.
Stem keywords: weaning, mechanical ventilation, tolerating, trial
Lead-in keywords: sign indicates, not tolerating
Negative lead-in flag: The question asks for a negative sign (intolerance).

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