LPN exams respiratory practice questions set 10

Correct answer:

Airway resistance follows Poiseuille's law (R ∝ 1/r^4), but total cross-sectional area governs overall resistance. The trachea, a single tube (~2 cm diameter), has ~3-4 cm² area. Bronchioles, numbering thousands, reach ~300 cm² collectively at terminal stages, yet pale beside alveoli. Alveoli (~300 million) total ~70-100 m² (~700,000-1,000,000 cm²) during inspiration, dwarfing other structures. This vast area slows airflow velocity, reducing resistance to negligible levels at the gas exchange site, where diffusion dominates. Resistance peaks in medium bronchi due to turbulent flow, not alveoli, despite their tiny individual size (~0.2 mm). Trachea and bronchioles handle bulk flow with higher resistance. Alveoli's massive area minimizes resistance, making them the correct choice, critical for efficient ventilation and distinguishing their role from conducting airways.

Correct answer:

Residual volume (RV) is the air remaining in the lungs after a maximal, forceful exhalation, typically 1-1.5 liters in adults. It prevents alveolar collapse and maintains gas exchange potential, measurable only indirectly (e.g., helium dilution). Tidal volume (VT) is the air moved in a normal breath (~500 ml), not after forceful effort. Expiratory reserve volume (ERV) is the extra air exhaled beyond a normal expiration (~1-1.5 L), expelled during forced exhalation, leaving RV behind. Vital capacity (VC) is the maximum air exhaled after maximal inhalation (ERV + VT + IRV, ~4-5 L), excluding RV. Inspiratory reserve volume (IRV) is additional air inhaled beyond a normal breath (~2-3 L), irrelevant here. RV's persistence reflects lung elasticity and chest wall mechanics, ensuring some air always remains, distinguishing it from volumes tied to active breathing phases or maximal efforts.

Correct answer:

Residual volume (RV) is the air remaining in the lungs after a maximal, forceful exhalation, typically 1-1.5 liters in adults. It prevents alveolar collapse and maintains gas exchange potential, measurable only indirectly (e.g., helium dilution). Tidal volume (VT) is the air moved in a normal breath (~500 ml), not after forceful effort. Expiratory reserve volume (ERV) is the extra air exhaled beyond a normal expiration (~1-1.5 L), expelled during forced exhalation, leaving RV behind. Vital capacity (VC) is the maximum air exhaled after maximal inhalation (ERV + VT + IRV, ~4-5 L), excluding RV. Inspiratory reserve volume (IRV) is additional air inhaled beyond a normal breath (~2-3 L), irrelevant here. RV's persistence reflects lung elasticity and chest wall mechanics, ensuring some air always remains, distinguishing it from volumes tied to active breathing phases or maximal efforts.

Correct answer:

Physiological dead space (VDphys) includes anatomic dead space (VDanat, ~150 ml, conducting airways) plus alveolar dead space (VDalv, ventilated but non-perfused alveoli). Normally, VDphys ≈ VDanat (~150 ml), but in disease, it's equal to or greater due to added VDalv. Lung diseases like pulmonary embolism increase VDphys by raising VDalv from poor perfusion. A high V/Q ratio (ventilation > perfusion), as in PE, also increases VDphys, as ventilated alveoli lack blood flow. However, VDphys isn't equal to alveolar dead space alone VDalv is just one component. VDphys = VDanat + VDalv, so stating it equals VDalv excludes the anatomic portion, which is always present (e.g., trachea, bronchi). This misdefinition is wrong, as physiological dead space encompasses both, not just wasted alveolar volume, a distinction critical for understanding gas exchange inefficiencies in pathology.

Correct answer:

The correct answer is B: more intense inhalation. The apneustic center is responsible for prolonging inhalation by stimulating the inspiratory neurons in the medulla oblongata. When the apneustic center is stimulated, it disrupts the normal breathing pattern, causing a prolonged and more intense inhalation. This results in deeper and more forceful breaths. Incorrect choices: A: increased respiratory rate - Stimulation of the apneustic center would not lead to an increased respiratory rate, but rather to changes in the depth and intensity of inhalation. C: a shorter respiratory cycle - The apneustic center's stimulation does not lead to a shorter respiratory cycle, but rather to a prolonged inhalation phase. D: less activity in the DRG center - The dorsal respiratory group (DRG) is responsible for initiating inspiration, and the apneustic center does not affect its activity.

Correct answer:

Idiopathic pulmonary fibrosis (IPF) scars lung interstitium, reducing elasticity and volumes. Functional residual capacity (FRC), the resting volume (~2.5-3 L normally), decreases in IPF (e.g., to 2 L) as stiff lungs limit expansion, a hallmark of restrictive disease. Tidal volume (VT, ~500 ml) typically decreases, not increases, as breathing becomes shallow due to restricted capacity, often requiring faster rates to maintain ventilation. Pulmonary vascular resistance rises, not falls, as fibrosis compresses capillaries, increasing resistance and risking right heart strain. Total lung capacity (TLC, ~6 L) also drops (e.g., to 4 L), reflecting reduced maximum volume, not higher. Lower FRC aligns with IPF's mechanics stiff lungs reduce resting and total volumes, impair gas exchange, and elevate work of breathing, distinguishing it from options contradicting restrictive physiology.

Correct answer:

Idiopathic pulmonary fibrosis (IPF) scars lung interstitium, reducing elasticity and volumes. Functional residual capacity (FRC), the resting volume (~2.5-3 L normally), decreases in IPF (e.g., to 2 L) as stiff lungs limit expansion, a hallmark of restrictive disease. Tidal volume (VT, ~500 ml) typically decreases, not increases, as breathing becomes shallow due to restricted capacity, often requiring faster rates to maintain ventilation. Pulmonary vascular resistance rises, not falls, as fibrosis compresses capillaries, increasing resistance and risking right heart strain. Total lung capacity (TLC, ~6 L) also drops (e.g., to 4 L), reflecting reduced maximum volume, not higher. Lower FRC aligns with IPF's mechanics stiff lungs reduce resting and total volumes, impair gas exchange, and elevate work of breathing, distinguishing it from options contradicting restrictive physiology.

Correct answer:

The correct answer is D, Impaired gas exchange. This is the priority because the client's O2 saturation of 88% indicates poor oxygenation, which can lead to serious complications like hypoxemia. The fever and nonproductive cough are symptoms of pneumonia contributing to impaired gas exchange. Addressing this issue is crucial to prevent respiratory distress. A: Fatigue - While important, fatigue is a secondary concern compared to impaired gas exchange, which directly affects oxygenation and can be life-threatening. B: Hyperthermia - The client's fever is likely related to the pneumonia but managing impaired gas exchange takes precedence as it directly impacts oxygen delivery to tissues. C: Impaired mobility - While assisting the client out of bed is necessary, the priority is to address the underlying problem of impaired gas exchange to prevent respiratory compromise.

Correct answer:

Physiological dead space (VDphys) includes anatomic dead space (VDanat, ~150 ml, conducting airways) plus alveolar dead space (VDalv, ventilated but non-perfused alveoli). Normally, VDphys ≈ VDanat (~150 ml), but in disease, it's equal to or greater due to added VDalv. Lung diseases like pulmonary embolism increase VDphys by raising VDalv from poor perfusion. A high V/Q ratio (ventilation > perfusion), as in PE, also increases VDphys, as ventilated alveoli lack blood flow. However, VDphys isn't equal to alveolar dead space alone VDalv is just one component. VDphys = VDanat + VDalv, so stating it equals VDalv excludes the anatomic portion, which is always present (e.g., trachea, bronchi). This misdefinition is wrong, as physiological dead space encompasses both, not just wasted alveolar volume, a distinction critical for understanding gas exchange inefficiencies in pathology.

Correct answer:

A lower tracheostomy involves an incision below the thyroid isthmus, typically between the 2nd and 4th tracheal rings, to create an airway. The superior thyroid artery (A) arises from the external carotid and supplies the upper thyroid, far from this site. The inferior thyroid artery (B), from the thyrocervical trunk, supplies the lower thyroid and lies posterior, near the recurrent laryngeal nerve, but is less exposed. The inferior thyroid veins (C) drain the thyroid plexus into the brachiocephalic veins, running anteriorly across the trachea, making them highly vulnerable during midline incision. The internal jugular vein (D) lies lateral, near the carotid sheath, and is less at risk unless the incision deviates significantly. Anatomical variations (e.g., a thyroid ima artery) exist, but C is the most consistently endangered due to its anterior position and delicate nature.