Pulse oximetry may not be a reliable indicator of oxygen saturation in which patient?
Patient with a fever
Patient who is anesthetized
Patient in hypovolemic shock
Patient receiving oxygen therapy
The Correct Answer is C
Pulse oximetry may not be a reliable indicator of oxygen saturation in a patient in hypovolemic shock, because this condition leads to severely reduced blood volume and peripheral perfusion. When there is inadequate circulation to the extremities, the pulse oximeter cannot detect strong pulsatile blood flow, resulting in inaccurate or falsely low readings. Poor perfusion interferes with the sensor’s ability to measure oxygen saturation correctly, making the results unreliable for assessing true arterial oxygenation.
Rationale for correct answer:
3. Patient in hypovolemic shock. In hypovolemic shock, severe fluid loss decreases circulating blood volume and compromises peripheral circulation. Because pulse oximeters rely on detecting pulsatile arterial blood flow, poor perfusion produces erratic or inaccurate oxygen saturation readings. Therefore, SpO₂ results should be interpreted cautiously, and arterial blood gases (ABGs) may be required for accurate assessment.
Rationale for incorrect answers:
1. Patient with a fever. Fever increases oxygen demand but does not affect pulse oximeter accuracy as long as perfusion is adequate.
2. Patient who is anesthetized. Pulse oximetry remains accurate during anesthesia with proper probe placement and perfusion.
4. Patient receiving oxygen therapy. Oxygen therapy raises SpO₂ but does not make readings unreliable; values still reflect actual oxygen saturation.
Take-home points:
- Pulse oximetry requires adequate perfusion and pulsatile flow for accuracy.
- Conditions like shock, hypothermia, or vasoconstriction may cause false or low readings.
- In hypovolemia, ABG analysis offers a more precise measure of oxygenation.
- Always interpret SpO₂ in context with the patient’s clinical condition and perfusion status.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
When auscultating the chest of an older patient in respiratory distress, it is best to begin listening at the lung bases. Air movement in the lower lobes is often the first area affected by fluid accumulation, atelectasis, or other pathological changes, making this the most effective starting point for detecting abnormal breath sounds.
Rationale for correct answer:
2. Begin listening at the lung bases. The lung bases are the most dependent areas and are commonly involved in early respiratory problems such as crackles from fluid overload, pneumonia, or atelectasis. Starting here ensures that the nurse identifies abnormal sounds where they are most likely to appear first. From there, the nurse moves upward to assess the full lung field for comparison and progression of sounds. This systematic approach helps detect even subtle changes in ventilation.
Rationale for incorrect answers:
1. Begin listening at the apices. Although the apices should be assessed, starting here may cause the nurse to miss early signs of congestion or collapse at the bases. The apices are less commonly affected in early respiratory distress.
3. Begin listening on the anterior chest. While anterior assessment is necessary, lung sounds—especially in conditions like heart failure or pneumonia—are often more prominent and diagnostically significant on the posterior side, particularly at the bases.
4. Ask the patient to breathe through the nose with the mouth closed. During auscultation, the patient should breathe slowly and deeply through the mouth, not the nose, to ensure maximal air movement and clearer breath sounds. Breathing through the nose may muffle or obscure important respiratory findings.
Take-home points:
- Start auscultation at the lung bases, where abnormalities are most likely to be detected first.
- Assess both posterior and anterior chest fields systematically for comparison.
- Instruct patients to breathe deeply through the mouth to enhance sound clarity.
- This method improves early detection of respiratory compromise in older adults, who are more prone to lower-lobe complications.
Correct Answer is D
Explanation
The nurse should interpret bronchial breath sounds in the lower lung fields as an abnormal finding. Normally, bronchial sounds are heard only over the trachea and mainstem bronchi. When these harsh, high-pitched sounds are heard in the peripheral lung areas, it indicates that lung tissue has become consolidated or filled with fluid, as seen in conditions such as pneumonia.
Rationale for correct answer:
4. Bronchial breath sounds in the lower lung fields. These sounds are characterized by a loud, tubular quality with a longer expiratory phase. In healthy lungs, the alveoli dampen bronchial sounds, so they should not be heard in the lower fields. Their presence there suggests abnormal air-to-fluid or air-to-solid ratios, typically caused by lung consolidation, atelectasis, or fibrosis. This finding warrants prompt investigation to identify the underlying pathology.
Rationale for incorrect answers:
1. Inspiratory chest expansion of 1 in. Normal chest expansion during inspiration is about 1 inch (2.5 cm) and should be symmetric. This finding is expected and indicates adequate lung inflation.
2. Percussion resonance over the lung bases. Resonance is the normal percussion tone over healthy lung tissue, reflecting air-filled alveoli. It indicates normal lung aeration and is not abnormal.
3. Symmetric chest expansion and contraction. Equal movement of both sides of the chest during breathing reflects normal respiratory mechanics and adequate bilateral lung expansion.
Take-home points:
- Bronchial breath sounds heard in peripheral or lower lung fields are a key sign of abnormal lung consolidation or fluid accumulation.
- Normal findings include resonant percussion tones and symmetric chest expansion.
- Recognizing changes in breath sound location or quality is essential for early detection of respiratory pathology.
- Document abnormal findings clearly and notify the provider for further evaluation, such as imaging or sputum testing.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.