SESSION TYPE: Critical Care Student/Resident Cases
PRESENTED ON: Monday, October 22, 2012 at 01:45 PM - 03:00 PM
INTRODUCTION: Asymmetric parenchymal lung disease causing hypoxemic respiratory failure can be difficult to manage with conventional and even rescue modes of ventilation due to different ventilation-perfusion ratios and compliances in the two lungs. Synchronous independent lung ventilation (SILV) with two ventilators has the potential to more effectively treat refractory hypoxemia by individually tailoring ventilation to each lung.
CASE PRESENTATION: A 55 year-old woman presented with dyspnea for 2 weeks. She reported fever, chills, productive cough with yellow sputum, and right-sided chest pain, started 1 week after returning from the Philippines. She was tachypneic and hypoxic with SaO2 88% on room air. A chest x-ray revealed a diffuse right-sided infiltrate, and a chest CT scan revealed a 7x6x4 cm rounded abscess in the densely consolidated right upper lobe (Figure 1), right lower lobe compression by a moderate pleural effusion, and mild left lower lobe atelectasis. Hypoxemia rapidly worsened, and she underwent emergency intubation. Due to persistent hypoxemia on Bilevel Pressure Control Ventilation with 100% FiO2 even after right chest tube insertion, she was started on Airway Pressure Release Ventilation (APRV), but the hypoxemia was refractory. Rescue ventilation with High Frequency Oscillation Ventilation (HFOV) was attempted, with 100% FiO2 and a mean airway pressure of 36 cmH2O, but her pO2 remained in the 40s. SILV was initiated after a double-lumen endotracheal tube was inserted, with the settings shown in Table 1. On 100% FiO2, her SaO2 improved to 94%. SILV was converted back to conventional ventilation with a single-lumen endotracheal tube 5 days later after the patient improved dramatically. Her Legionella urine antigen was positive, and she was treated with azithromycin and moxifloxacin for 3 weeks, at which point she was weaned off oxygen and discharged.
DISCUSSION: In SILV, the respiratory rate is kept the same for both lungs, while PEEP, tidal volumes, and inspiratory flow rates are set independently. This patient's hypoxemia likely improved with SILV by avoiding overdistention of the more compliant lung, thus minimizing shunting of blood flow to the more diseased lung. SILV may have also been more lung protective, as low tidal volumes accounting for the different compliances of each lung could be used, and higher PEEP could be applied selectively to the more affected lung to improve alveolar recruitment, without overdistending the less affected lung.
CONCLUSIONS: Legionella can cause a severe necrotizing pneumonia, and a Legionella urinary antigen should be ordered in critically-ill pneumonia patients, especially if risk factors are present. SILV is a viable rescue option for persistent hypoxemia from asymmetric parenchymal lung disease which is not corrected by conventional and rescue modes of ventilation.
1) Anantham D, Jagadesan R, Tiew PE. Clinical review: Independent lung ventilation in critical care. Crit Care. 2005;9(6):594-600.
DISCLOSURE: The following authors have nothing to disclose: Ekamol Tantisattamo, Reid Ikeda
No Product/Research Disclosure InformationDepartment of Medicine, University of Hawaii John A. Burns School of Medicine, Honolulu, HI