Combined pulmonary fibrosis and emphysema in a smoker with apparently normal lung volumes

History of present illness

A 63-year-old man went to the outpatient pulmonology clinic complaining of shortness of breath on exertion, which progressively worsened during the past year.

A previous chest radiograph revealed hyperexpanded lungs with a slightly increased transparency in the upper fields and a coarse reticular interstitial pattern in the lung bases and subpleural areas ( Fig 8.1 ).

Past medical history

The patient was a heavy smoker (about 30 cigarettes a day for 40 years equals to 60 pack-years; in the past 3 months he had reduced to 4 or 5 cigarettes a day). He had worked as a construction worker for many years with professional exposure to cement dust and asbestos.

Moreover, the patient was overweight with a body mass index of 29 and had high blood pressure and type 2 diabetes. He routinely took metformin and ramipril.

For some years, he had been experiencing acute bronchitis episodes in the winter months, for which he usually took antibiotics.

About 1 year earlier, his general practitioner (GP) prescribed spirometry, which showed preserved lung volumes. In particular, the values of forced expiratory volume in 1 second (FEV ₁ ), forced vital capacity (FVC), and their ratio (FEV ₁ /FVC) were within the normal limits. Thus, no long-term inhalation therapy was prescribed. The GP and pulmonologist advised the patient to quit smoking.

Due to the persistence of breathlessness and productive cough, the GP ordered a chest radiograph and an outpatient pulmonology visit.

Physical examination and early clinical findings

At the time of the visit to the pulmonology clinic, the patient was eupneic at rest but complained of shortness of breath under moderate efforts such as walking at a fast pace or climbing stairs. He often coughed with some sputum, especially in the morning, but he considered this normal as he used to smoke a lot. His wife referred that he usually snored a lot at night. When the doctors asked if he was sleepy during the day, he replied that he fell asleep easily in many circumstances such as when watching TV, sitting in an armchair, or even while in the hospital waiting room.

Oxygen saturation measured by pulse oximetry (SpO ₂ ) was 92% in room air. Chest examination revealed a diffuse reduction in vesicular breath sounds and crackles in both lung bases. He had no pallor or finger clubbing. Recent blood tests showed quite high values of hemoglobin (Hb 18.2 g/dL; normal range for adult males 13.8–17.2 g/dL) and hematocrit (Hct 54.8%; normal range for adult males 42–52%). Leukocytes, platelets, liver and kidney function, electrolytes, and inflammatory indices were all normal.

Clinical course

The patient repeated pulmonary function tests (PFTs, Fig 8.2 ), which showed again preserved lung volumes and airflow rates, although they were near the lower limits of normal. Moreover, there was a severe increase in airway resistances and an impairment of the diffusing capacity for carbon monoxide (DLCO 48% predicted).

An arterial blood gas analysis confirmed just sufficient arterial oxygen levels at rest (pO ₂ 63.5 mmHg), with normal acid-base balance and partial pressure of carbon dioxide (pH 7.39, pCO ₂ 41 mmHg).

At the 6-minute walk test (6MWT, Fig 8.3 ), the patient covered a distance of 510 m, corresponding to 85% of predicted, experienced somewhat severe dyspnea (score 4 on the 10-point Borg dyspnea scale), and had oxygen desaturation (lowest SpO ₂ 85%, mean SpO ₂ 89%).

The patient underwent HRCT of the chest, which revealed bilateral emphysema, mainly in the upper lobes, and fibrosis with a usual interstitial pneumonia (UIP) pattern including honeycombing in the dorsal and peripheral areas of the lower lobes ( Fig 8.4 ).