Clinical diagnosis
Case 272
【Progress】
She was given steroid pulse treatment using methyl prednisolone 2000mg X 2/day for 3 days and thereafter, steroid was reduced until maintenance doses. She discharged hospital and continued small doses of predonine to prevent recurrence of UIP exacerbation.
【Discussion】
Pulmonary hypertension (PH) is defined that pressure of pulmonary artery is 25mm Hg or greater: < 20mm Hg or less is normal and 20 to 24 mmHg equivocal (1). PH seen in atrial septal defect indicates dilatation of pulmonary artery from proximal to distal pulmonary artery. Meanwhile, pulmonary hypertension seen in pulmonary embolism or interstitial pulmonary disease, indicates occlusion of pulmonary artery or rapidly peripheral pulmonary artery stenosis (2, 3). In latter situations, sudden cardiac failure possibly occurs because right ventricular wall is not so thick as to push out blood volume in right ventricle against PH. It causes sudden loss of consciousness and/or cardiac arrest. PH seen in UIP exacerbation is one of the risk factors for poor prognosis.
Radiologic findings of exacerbation of UIP are ground glass opacity of functional pulmonary parenchyma associated with honey comb pattern at the basal pulmonary area. The problem is the origin of ground glass opacity in UIP exacerbation. If ground glass opacity arose from active interstitial pneumonia, it would cause elevation of KL-6 and LDH which indicate damages of pulmonary cell II and pulmonary cell I. Laboratory test of our patient revealed KL-6 value was within normal limits and LDH elevated slightly, implying almost no damages of pulmonary cell I and II, but marked elevation of BNP which secrets from cardiac muscle, implying cardiac dysfunction. However, chest CT showed no typical cardiac congestion: the diameter of upper lobe bronchus is almost the same as that of upper lobe pulmonary artery which indicates a normal pattern (4-8). However, the diameter of pulmonary trunk is almost the same as that of ascending aorta. It is reported that pulmonary artery hypertension induces to dilate the lumen of main pulmonary artery whose size is 29 mm or greater than the lumen of ascending aorta on CT (2-8). Further, pulmonary branch arteries become abruptly stenosis, indicating high pressure of pulmonary artery. Namely, in our patient, main pulmonary artery is dilated and peripheral pulmonary branch artery is narrowed, indicative of pulmonary hypertension. As a result, waste blood from dilated lumen of main or first branch to narrowing peripheral branch overflow to the interstitial, causing interrupting exchange of oxygen and carbon dioxide, indicative of leading respiratory failure. Further, overload of right ventricle for pulmonary hypertension weakens its output, resulting in circulatory insufficiency and loss of consciousness due to decrease of brain blood flow.
The management of pulmonary hypertension is to dilate the lumen of peripheral pulmonary branch artery. Warming limbs and slowly deep breath and O2 inhalation might be effective to prevent the worsening of pulmonary hypertension.
【Summary】
We presented a ninety five-year-old female suffering from dyspnea and loss of consciousness. Respiratory failure was confirmed that SpO2 was 88 mmHg. Chest CT depicted ground glass opacity in the pulmonary parenchyma with honey-comb pattern of pulmonary basement areas. Effusion of interlobular septum with less pleural effusion was also demonstrated on CT, indicative of effusion coming from pulmonary parenchyma. It is borne in mind that when exacerbation of UIP is suspected on CT, it is crucial whether pulmonary hypertension is responsible or not. It indicates pulmonary hypertension on CT that diameter of the main portal artery is 29 mm or greater and/or the diameter of pulmonary artery is equal or greater than that of ascending aorta. The interstitial ground glass opacity of pulmonary parenchyma with septal effusion, a sign of exacerbation of UIP might arise from the waste flow from dilated main and first branch pulmonary artery to abruptly stenotic peripheral branch artery. Then, CT findings and values of BNP are crucial indicators of pulmonary hypertension and overload of right ventricle.
【References】
1.Zapol, WM, Snider MT. Pulmonary hypertension in severe acute respiratory failure. N Engl J Med. 1977; 296:476-480.
2.Peña E et al. Pulmonary Hypertension: How the Radiologist Can Help. Radiographics 2012; 30: Chest ImagingFree Access. Published Online:Dec 30 2011 https://doi.org/10.1148/rg.321105232
3.Tan RT, et al. Utility of CT scan evaluation for predicting pulmonary hypertension in patients with parenchymal lung disease. Medical College of Wisconsin Lung Transplant Group. Chest 1998;113(5): 1250–1256.
4.Edwards PD, et al. CT measurement of main pulmonary artery diameter. Br J Radiol 1998;71(850):1018–1020.
5.Devaraj A, Hansell DM. Computed tomography signs of pulmonary hypertension: old and new observations. Clin Radiol 2009;64(8):751–760.
6.Ng CS, et al. A CT sign of chronic pulmonary arterial hypertension: the ratio of main pulmonary artery to aortic diameter. J Thorac Imaging 1999;14(4):270–278.
7.Devaraj A, et al. Detection of pulmonary hypertension with multidetector CT and echocardiography alone and in combination. Radiology 2010;254(2): 609–616.
8.Revel MP, et al. Pulmonary hypertension: ECG-gated 64-section CT angiographic evaluation of new functional parameters as diagnostic criteria. Radiology 2009;250(2):558–566.
2022.7.21