The critical care nurse controls the mechanical ventilator's tidal volume, which ranges from

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2022

Medical & Surgical Nursing

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2022

Explanation

Tidal volume (Vt) is the amount of air delivered to the lungs with each ventilator breath, calculated based on ideal body weight.
Modern lung-protective strategies, especially for conditions like ARDS, recommend low tidal volumes, typically in the range of 4-8 mL/kg.
This approach minimizes ventilator-induced lung injury (VILI) by preventing overdistension of the alveoli (volutrauma) and excessive airway pressure (barotrauma).
The range of 5-15 mL/kg is the only option provided that includes these safe, lower volumes, although volumes above 10 mL/kg are now used very cautiously.
Higher volumes, once common, are now known to increase morbidity and mortality.

Option B: A tidal volume of 15-25 mL/kg is dangerously high and would cause significant overstretching of the alveoli, leading to volutrauma and barotrauma.
Option C: A tidal volume of 25-35 mL/kg is extremely high and would likely cause immediate and severe lung injury, such as pneumothorax and acute cardiovascular compromise.
Option D: A tidal volume of 35-45 mL/kg is a catastrophic level of volume that is incompatible with life. It would cause massive lung rupture.

Clinical Relevance

Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Mechanical Ventilation: Tidal Volume Settings in acute care settings.
Nurses are responsible for ensuring ventilator settings are applied correctly and for monitoring the patient's tolerance. This includes calculating tidal volume based on ideal body weight (IBW), not actual weight, to prevent volutrauma in overweight or obese patients.
Constant vigilance for signs of complications is key. This includes listening for decreased breath sounds (potential pneumothorax), observing for asymmetrical chest movement, and monitoring for sudden drops in blood pressure or oxygen saturation.
What if? If a patient on a standard Vt of 8 mL/kg develops ARDS (evidenced by worsening hypoxemia and new bilateral infiltrates on chest X-ray), the nurse should anticipate an immediate order to decrease the tidal volume to a lung-protective level of 4-6 mL/kg to mitigate further lung injury.

How to Approach the Question

First, identify the key terms in the question: 'mechanical ventilator' and 'tidal volume'.
This is a factual recall question that tests your knowledge of standard ventilator settings.
Recall the modern clinical principle of 'lung-protective ventilation', which emphasizes using lower tidal volumes to prevent injury.
Think about the typical safe range. The standard of care is around 6-8 mL/kg of ideal body weight.
Evaluate the given options. Look for the range that includes these safe, lower values.
Eliminate any options that start at or consist entirely of dangerously high volumes (e.g., anything starting at 15 mL/kg or higher). The only plausible option is the one that covers the 5-8 mL/kg range.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 672-674, 673-675

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