A full-term newborn infant is having episodes of cyanosis and apnea, which are worse when he is attempting to feed, but he seems better when he is crying. Which of the following is the most important next step to quickly establish the diagnosis?
b. Ventilation perfusion scan
c. Passage of catheter into nose
d. Hemoglobin electrophoresis
e. Bronchoscopic evaluation of palate and larynx
the answer is below…
The United States Medical Licensing Examination, or USMLE for short, is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.
The USMLE assesses a physician’s ability to apply knowledge, concepts, and principles, and to determine fundamental patient-centered skills that are important in health and disease and that constitute the basis of safe and effective patient care.Examination committees composed of medical educators and clinicians from across the United States and its territories prepare the examination materials each year.
This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently.
The USMLE is actually comprised of three different exams that are referred to as steps, which examine the individual’s knowledge of specific topics related to the field of medicine such as basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.
All three steps of the USMLE include a series of computerized multiple-choice questions, but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual’s ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.
The correct answer is c; Passage of catheter into nose.
It is important to make the diagnosis of choanal atresia quickly because it responds to treatment but can be lethal if unrecognized and untreated. Most neonates are obligate nose breathers and cannot breathe adequately through their mouths. Infants with choanal atresia have increased breathing difficulty during feeding and sleeping and improved respirations when crying. A variety of temporizing measures to maintain an open airway have been used, including oropharyngeal airways, positioning, tongue fixation, and endotracheal intubation, but surgical correction with placement of nasal tubes is most effective. The diagnosis can be made by failure to pass a catheter through the nose to the pharynx. Bronchoscopy would help diagnose lower airway anomalies. A ventilation-perfusion scan would be the appropriate examination if you were concerned about mismatch (e.g., that associated with pulmonary embolism). A newborn with a hemoglobinopathy such as sickle cell or thalassemia would not present as this infant did, so an electrophoresis would not be helpful. An echocardiogram would be useful if you suspected congenital cyanotic heart disease. The lack of a murmur in a newborn does not rule out pathology; this would be a reasonable next step if the catheter passed through both nares without difficulty.