INTRODUCTION: Severe lobar venoarterial shunting in bronchioloalveolar cell carcinoma (BAC) has been infrequently reported [1,2]. A patient with BAC is presented with a severe right lower lobe venoarterial shunt corrected by pulmonary artery occlusion and effectively palliated with a right lower lobectomy.
CASE PRESENTATION: A 69-year-old Caucasian female with a four year history of advanced BAC was referred for severe refractory hypoxemia. She presented to the hospital with a resting oxygen saturation (SaO2) between 60 to 80%, despite high flow oxygen supplementation. She reported severe dyspnea, malaise, productive cough and an inability to ambulate 20 feet. Examination revealed a thin, alert, cyanotic and dyspneic woman. Vital signs were heart rate 102/min, blood pressure 97/62 mmHg, temperature 37 °C and respiratory rate 24/min. Lung examination revealed inspiratory crackles, egophony and dullness to percussion confined to the right middle and lower lobes. Cardiac examination revealed tachycardia with normal heart sounds and no murmurs. Peripheral pulses were normal. Acrocyanosis was present. The remainder of the physical examination was noncontributory. Complete blood count revealed a hemoglobin of 17.6 g/dL and hematocrit of 50%. Complete metabolic panel was normal. Resting arterial blood gas on 8 Lpm oxygen demonstrated a pH of 7.47, PaCO2 of 29 torr, PaO2 of 38 torr and SaO2 of 76%. Chest roentgenography and computed tomography demonstrated consolidation and air bronchograms within the right middle and lower lobes [Figure 1]. Ventilation-perfusion scan demonstrated low probability of pulmonary embolus and 49% differential perfusion to the right middle and lower lung zones [Figure 2]. Transthoracic echocardiography demonstrated normal left ventricular ejection fraction, a mildly dilated aortic root and no intracardiac shunt. Right heart catheterization and pulmonary angiography were performed. Mean pulmonary arterial and capillary occlusion pressures were within normal limits. Fick cardiac index was 4.1 L/min/m2, systemic vascular resistance was 1042 dyne/sec/cm3 and pulmonary vascular resistance was 78 dyne/sec/cm3. Mixed venous arterial saturation was 70%. SaO2 on supplemental oxygen was 77% but improved to 93% following occlusion of the right lower pulmonary artery. Pulmonary angiography demonstrated normal pulmonary arterial vasculature. Following a thorough preoperative evaluation and consent process, a right thoracotomy with resection of the right lower lobe was performed. Division of the right lower lobe pulmonary artery resulted in improvement in SaO2 from 78% to 92% on single lung ventilation. Following an unremarkable postoperative course, the patient was discharged to home requiring no supplemental oxygen. Four months following surgery, she remains off of oxygen and no longer describes activity-limiting dyspnea. Room air SaO2 with ambulation remains 93%.
DISCUSSIONS: Pulmonary resection for metastatic non-small cell carcinoma of the lung (stage IV) is relatively contraindicated. However, this patient experienced severe symptoms and hypoxemia related to a shunt through lung densely consolidated with tumor. Demonstration of reversibility of the venoarterial shunt by selective pulmonary artery occlusion and abrogation of her supplemental oxygen requirement was key in determining candidacy for palliative lobectomy.
CONCLUSION: Severe isolated lobar venoarterial shunting associated with BAC is an uncommon complication of disease that may result in debilitating sequelae. Though surgical intervention does not cure the underlying malignancy, in select cases, where symptomatic shunting can be localized and corrected, palliative resection may afford a significant improvement in quality of life.
DISCLOSURE: Peter Crossno, None.