Which diagnostic test confirms cystic fibrosis?
Sweat chloride test.
Pulmonary function test.
Chest X-ray.
Sputum culture.
The Correct Answer is A
Choice A rationale
The sweat chloride test is the gold standard diagnostic test for cystic fibrosis (CF). CF is caused by a mutation in the CFTR gene, which impairs chloride ion transport across epithelial cells. This defect leads to abnormally high chloride concentration in sweat, typically >60 mEq/L in children, which provides biochemical confirmation of the disease.
Choice B rationale
Pulmonary function tests (PFTs) measure lung volumes and airflow, typically revealing an obstructive pattern in CF due to chronic infection and inflammation. While they monitor disease progression and severity, PFTs are not diagnostic for the underlying genetic disorder that defines cystic fibrosis.
Choice C rationale
A Chest X-ray (CXR) may show characteristic findings of chronic lung disease in CF, such as bronchiectasis, hyperinflation, or atelectasis, reflecting the disease's pulmonary complications. However, the CXR is an imaging tool for assessing lung structure, not a diagnostic test for the systemic genetic condition itself.
Choice D rationale
Sputum cultures are used to identify the specific bacterial pathogens, such as Pseudomonas aeruginosa or Staphylococcus aureus, colonizing the airways of CF patients. While essential for guiding antibiotic therapy, a sputum culture only detects secondary infection and does not confirm the diagnosis of cystic fibrosis.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
Weight gain of 1 kg suggests fluid retention, which is contrary to the expected diuretic effect of furosemide. Furosemide, a loop diuretic, acts by inhibiting the Na+-K+-2Cl- cotransporter in the thick ascending limb of the loop of Henle, increasing water and electrolyte excretion. A decrease in body weight due to diuresis is the primary indicator of effectiveness in reducing fluid overload associated with CHF.
Choice B rationale
Decreased urine output indicates a diminished response to the diuretic, suggesting ineffectiveness or potential complications like dehydration or pre-renal injury. Effective diuresis should significantly increase the urine output, facilitating the removal of excess interstitial and intravascular fluid volume to alleviate the symptoms of pulmonary and systemic congestion in CHF. Normal urine output for children is typically 1 to 2 mL/kg/hr.
Choice C rationale
Increased crackles, also known as rales, are adventitious lung sounds that signify the presence of fluid in the alveoli and small airways, characteristic of pulmonary edema in CHF. Furosemide aims to decrease this fluid, improving oxygenation and reducing the audible crackles, making an increase an indicator of worsening condition or ineffective treatment.
Choice D rationale
Decreased respiratory rate often accompanies improved oxygenation and reduced work of breathing, secondary to the resolution of pulmonary congestion and edema. Furosemide's action reduces the fluid burden on the lungs, lowering the hydrostatic pressure and facilitating gas exchange, which in turn reduces the tachypnea and respiratory distress common in pediatric CHF.
Correct Answer is ["A","B","C","E"]
Explanation
Choice A rationale
Photophobia, or an extreme sensitivity to light, is a common symptom in meningitis, resulting from the meningeal irritation and inflammation caused by the bacterial infection. The meninges, the protective layers covering the brain and spinal cord, contain pain-sensitive fibers. When inflammation reaches the optic nerve pathways or specific cranial nerves, light perception becomes a painful stimulus.
Choice B rationale
A petechial or purpuric rash is a critical and potentially ominous finding, especially in meningococcemia (caused by Neisseria meningitidis). The rash is caused by endothelial damage and vasculitis as the bacteria and inflammatory mediators enter the bloodstream, leading to small, non-blanching hemorrhages beneath the skin due to capillary leakage and microthrombi formation.
Choice C rationale
Nuchal rigidity (stiffness of the neck), a classic sign, is caused by inflammation of the meninges surrounding the cervical spinal cord. Attempting to flex the neck stretches the irritated meninges, eliciting pain and muscle spasm. This rigidity is often assessed using maneuvers like Brudzinski's or Kernig's signs, indicating meningeal irritation.
Choice D rationale
A high-pitched cry is more commonly associated with increased intracranial pressure (ICP), which can be a complication of severe meningitis, particularly in infants due to hydrocephalus or cerebral edema. While a sign of neurological distress, it is a less direct or specific initial symptom compared to the direct signs of meningeal irritation or systemic infection.
Choice E rationale
Seizures are a frequent complication, particularly in infants and young children with bacterial meningitis. They result from the direct inflammatory irritation of the cerebral cortex by the infectious process, cerebral edema, or vascular changes (e.g., thrombosis, infarcts) associated with severe intracranial infection, causing abnormal electrical activity.
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