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.There isno evidence that yearly pulmonary function testing will affect the disease process orprovide any added information for intervention.(Answer: E Yearly pulmonary functiontesting to monitor progress)41.A 36-year-old black man presents to the emergency department after a motor vehicle accident.Except forsome minor scrapes, he is asymptomatic; however, his chest x-ray reveals an elevated left hemidiaphragm.Which of the following tests can confirm the diagnosis?Q' A.Determination of DLco on pulmonary function testingQ' B.Arterial blood gas measurementsQ' C.Sniff testQ' D.Pulse oximetryQ' E.CT scan of the chestKey Concept/Objective: To understand the evaluation and diagnosis of a patient with unilater-al diaphragmatic paralysisUnilateral diaphragmatic paralysis is most often detected as a radiographic finding inan asymptomatic patient.Although most cases are the result of neoplastic invasion ofthe phrenic nerve, it is also commonly seen in postoperative patients, in patients withtrauma, or in idiopathic cases.The sniff test involves asking the patient to perform asudden, forceful inspiration.The diaphragmatic movements can be viewed under fluo-roscopy; with unilateral diaphragmatic paralysis, the affected side of the diaphragmascends into the thorax.This movement is in the opposite direction of the normal side.Such a finding confirms the diagnosis of diaphragmatic paralysis.(Answer: C Sniff test)42.A 26-year-old woman presents to the emergency department with shortness of breath, which has beenprogressively increasing for several days.She has also been experiencing increasing weakness and dou-ble vision.She notes a worsening of her symptoms at the end of the day, and she has noticed weaknesswhile brushing her hair.Her physical examination is unrevealing.Which of the following neuromuscular disorders is most likely the cause of this patient's symptoms?26 BOARD REVIEWQ' A.Guillain-Barré syndromeQ' B.Bilateral diaphragmatic paralysisQ' C.Myasthenia gravisQ' D.Duchenne muscular dystrophyQ' E.Amyotrophic lateral sclerosis (ALS)Key Concept/Objective: To be able to differentiate between the multiple neuromuscular disor-ders that affect respiratory functionGuillain-Barré syndrome usually presents as an ascending paralysis.Although bilateraldiaphragmatic paralysis would explain this patient's shortness of breath, the proximalmuscle weakness and ocular symptoms would remain unexplained.Duchenne muscu-lar dystrophy is an X-linked disorder that exclusively affects males.Its symptoms arepresent by 3 to 5 years of age, and patients are usually wheelchair bound by 12 years ofage.The majority of patients with ALS present clinically with progressive asymmetricalweakness, fasciculations, and prominent muscle atrophy.The distal musculature is pri-marily involved.Myasthenia gravis is an autoimmune disorder that affects the neuro-muscular junction: specifically, the postsynaptic acetylcholine receptor.Patients usual-ly present with intermittent symptoms that are usually worse at the end of the day.Respiratory failure may occur; in myasthenia crisis, the patient requires a ventilator.(Answer: C Myasthenia gravis)For more information, see Staton GW, Ingram RH Jr: 14 Respiratory Medicine: VIIDisorders of the Chest Wall.ACP Medicine Online (www.acpmedicine.com).Dale DC,Federman DD, Eds.WebMD Inc., New York, December 2003Respiratory Failure43.A 41-year-old woman presents to the emergency department for evaluation of shortness of breath.Sheis currently undergoing therapy for newly diagnosed breast cancer.She states that she was in her usualstate of health until she began to experience acute shortness of breath 2 hours ago.For the past 2 hours,she has also been experiencing sharp right chest pain on inspiration.She denies having fever, chills, orcough.Results of physical examination are as follows: heart rate, 130 beats/min; respiratory rate, 30breaths/min; a loud second heart sound; and there is mild pretibial pitting edema of the left lowerextremity.Results of blood gas measurements are as follows: normal pH; arterial carbon dioxide tension(PaCO2), 17 mm Hg; arterial oxygen tension (PaO2), 70 mm Hg; and hemoglobin O2 saturation, 95%.Thepatient is started on anticoagulation therapy with heparin, and a helical CT scan of the chest is ordered.Which of the following statements regarding acute hypoxemic respiratory failure is true?" "Q' A.This patient has no significant V/Qmismatching because her hemo-globin saturation is normalQ' B.In patients with ARDS, shunting is the major physiologic derange-ment resulting in hypoxemiaQ' C.Pure alveolar hypoventilation is the most common pathophysiolog-ic cause of acute hypoxemia" "Q' D.Shunting and V/Qmismatching respond similarly to inhalation of100% O2Key Concept/Objective: To know the clinical characteristics of common causes of hypoxemiaPatients with ARDS can have diffusion impairments that contribute to hypoxemia, butshunting is the more important physiologic derangement in this disorder.The alveolar-" "arterial oxygen gradient or difference (A-aDO2) is used to identify V/Q mismatching" "when the measured PaO2 is normalized by hyperventilation.V/Q mismatching is themost common pathophysiologic cause of acute hypoxemia.It develops when there is adecrease in ventilation to normally perfused regions of the lung, a decrease in perfusionto normally ventilated regions of the lung, or some combination of a decrease in both14 RESPIRATORY MEDICINE 27" "ventilation and perfusion.Shunting can be differentiated from V/Q mismatching on thebasis of the differences in the response to inhalation of 100% oxygen.(Answer: B Inpatients with ARDS, shunting is the major physiologic derangement resulting in hypoxemia)44.A 74-year-old male patient of yours who has severe COPD presents to your office for the evaluation ofworsening shortness of breath.The patient has smoked two packs of cigarettes daily for the past 50 years.Through home oxygen therapy, he receives oxygen at a rate of 2 L/min.He states that he was in his usualstate of health until 2 days ago, when he developed worsening shortness of breath, particularly withexertion.He also complains of mild substernal  burning pain with exertion.He denies having orthop-nea, edema, or palpitations.His hemoglobin O2 saturations are 92% on 2 L of oxygen provided by nasalcannula.Results of blood gas measurements are as follows: pH, 7.38; PaCO2, 80 mm Hg; and PaO2, 70 mmHg.ECG shows lateral T wave inversions; otherwise, ECG results are unremarkable [ Pobierz caÅ‚ość w formacie PDF ]