Which assessment alerts the nurse to the possibility that the intrathoracic pressure in a mechanically ventilated client is too high?
Increased diaphragmatic excursion.
Low-pressure alarm sounds on the ventilator.
Hypotension.
Pulse oximetry value of 96
The Correct Answer is C
Choice A rationale
Increased diaphragmatic excursion is not a typical indicator of excessively high intrathoracic pressure. In fact, high pressure from mechanical ventilation often limits the movement of the diaphragm because the lungs are over-inflated, potentially pushing the diaphragm downward and restricting its natural range of motion. Diaphragmatic excursion is a measure of the distance the diaphragm moves during inhalation and exhalation, and its assessment is more common in spontaneous breathing than in high-pressure mechanical ventilation monitoring.
Choice B rationale
A low-pressure alarm on a ventilator usually indicates a leak in the system, a disconnection of the tubing, or a cuff leak in the endotracheal tube. It signifies that the intended pressure is not being reached or maintained. Conversely, excessively high intrathoracic pressure would trigger a high-pressure alarm, which alerts the nurse to obstructions, coughing, biting the tube, or decreased lung compliance, rather than the low-pressure notification described in this particular choice.
Choice C rationale
Hypotension is a critical clinical alert for high intrathoracic pressure. When positive pressure ventilation increases pressure within the chest cavity, it compresses the superior and inferior vena cava. This compression reduces venous return to the right atrium, leading to decreased cardiac preload. Consequently, the stroke volume and cardiac output drop, resulting in a systemic decrease in blood pressure. Monitoring for hypotension is essential to prevent hemodynamic instability caused by excessive peak inspiratory pressures or peep.
Choice D rationale
A pulse oximetry value of 96 percent (normal range 95 to 100 percent) is a reassuring sign of adequate arterial oxygen saturation and does not indicate a problem with intrathoracic pressure. While high pressures can sometimes improve oxygenation by recruiting alveoli, a normal reading does not alert the nurse to the dangers of barotrauma or cardiovascular collapse associated with excessive pressure. Changes in blood pressure are much more sensitive and immediate indicators of the hemodynamic consequences of high pressure.
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Naxlex Comprehensive Predictor Exams
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Correct Answer is D
Explanation
Choice A rationale
This description more accurately reflects the function of pressure support or tidal volume settings on a ventilator. Positive end-expiratory pressure does not focus on the inspiratory phase or pushing air in; instead, it acts during the expiratory phase. The goal is to maintain a specific level of pressure within the circuit at the end of a breath to ensure that the internal architecture of the lung remains open for gas exchange.
Choice B rationale
While PEEP is vital in managing the symptoms of ARDS and improving oxygenation, it does not directly prevent the underlying inflammatory processes that lead to lung fibrosis. Fibrosis is a late-stage complication of the proliferative phase of ARDS characterized by the excessive deposition of collagen. PEEP is a supportive measure to manage alveolar recruitment and oxygenation rather than a curative treatment that halts the cellular progression toward permanent scarring.
Choice C rationale
PEEP is a pressure setting, not a measure of the fraction of inspired oxygen. The delivery of 100 percent oxygen refers to the FiO2 setting. While PEEP can help improve the efficiency of oxygenation, allowing for a lower FiO2 to be used to achieve adequate arterial oxygen levels, it is not the mechanism that delivers the oxygen itself. Its primary function is mechanical stabilization of the alveolar units during the breathing cycle.
Choice D rationale
In ARDS, fluid leakage and loss of surfactant cause alveoli to become unstable and collapse, a process known as atelectasis. PEEP provides constant pressure at the end of exhalation to keep these air sacs open, which increases the surface area available for gas exchange and improves arterial oxygenation. By preventing repetitive opening and closing of alveoli, PEEP also helps reduce ventilator-induced lung injury, which is a common risk in severe respiratory failure.
Correct Answer is C
Explanation
Choice A rationale
While equipment failure is a possibility in clinical settings, it is statistically unlikely for a stethoscope earpiece to fail exactly after a tube-securing procedure. A defective earpiece would typically result in diminished or absent sounds bilaterally rather than a localized absence on the left side only. Nurses must first prioritize physiological and procedural complications before assuming mechanical failure. Immediate troubleshooting should focus on the patient's airway anatomy and the placement of the endotracheal tube.
Choice B rationale
A pneumothorax involves the presence of air in the pleural space, which can cause lung collapse and absent breath sounds. While this is a serious complication, it is less common immediately following the simple act of retaping an endotracheal tube. Pneumothorax usually presents with sudden respiratory distress, tracheal deviation, and pleuritic chest pain. In this specific scenario, the mechanical movement of the tube during the securing process points more directly toward a displacement into the airway branches.
Choice C rationale
The right mainstem bronchus is more vertical, shorter, and wider than the left, making it the most frequent site for accidental tube migration. If an endotracheal tube is pushed too far during securing, it will likely enter the right side, effectively bypassing the left lung. This results in normal breath sounds on the right but absent sounds on the left. The nurse must recognize this anatomical predisposition and prepare to withdraw the tube slightly to restore bilateral ventilation.
Choice D rationale
Aspiration of secretions can cause crackles, rhonchi, or diminished breath sounds, but it rarely causes a total and sudden absence of sound across all left lung fields. Aspiration usually leads to localized consolidation or chemical pneumonitis over a longer period. The acute nature of the change immediately after manipulating the tube strongly suggests a mechanical displacement. Suctioning might be necessary, but the priority is confirming the depth of the tube via auscultation and chest radiography.
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