By Eman I. Desoki MsC, Intensive Care Medicine. ICU Fellow Assistant in NHTMRI. Objectives To understand the definition of restrictive lung diseases & its pathophysiology. To know how they present to the critical care settings. To know how to approach with these group of patients. I- Classification of Respiratory Diseases 1- Inflammtory 2- Obstructive 3- Pulmonary vascular diseases 4- Infectious 5- Neoplastic 6- Restrictive II- Definition of Restrictive Lung Diseases: These are diseases that are characterized by reduced lung volume, either because of an alteration in lung parenchyma or because of a disease of the pleura, chest wall , or neuromuscular apparatus. II- Definition of Restrictive Lung Diseases: In physiological terms, restrictive lung diseases are characterized by : - Reduced total lung capacity ( TLC) - Reduced vital capacity or reduced resting lung volume. ( VC) Accompanying characteristics are : - Preserved airflow and - Normal airway resistance, which are measured as the functional residual capacity ( FRC). III-Causes of Restrictive Lung Diseases: A- Intrinsic lung diseases; diseases of the lung parenchyma: -Organic dust exposure e.g. farmer's lung, bagassosis, and mushroom worker lung, which all cause hypersensitivity pneumonitis. -Inorganic dust exposure e.g. silicosis, asbestosis, talc, pneumoconiosis, berylliosis, hard metal fibrosis, coal worker‘s pneumoconiosis. -Collagen vascular disease e.g. including scleroderma, polymyositis, dermatomyositis, systemic lupus erytheromatosis, rheumatoid arthritis, and ankylosing spondylitis. -Idiopathic e.g. acute interstitial pneumonia, idiopathic pulmonary fibrosis. III-Causes of Restrictive Lung Diseases: B- Extrinsic disorders; or extraparenchymal diseases: - Chest wall disease: severe kyphosis & scoliosis - Pleural diseases: massive effusion & tension pneumothorax - Neuromuscular diseases: Myasthenia Gravis & Guillain Barre $ IV- Pathophysiology: In cases of intrinsic lung disease, the excessive elastic recoil of the lungs, in comparison to the outward recoil forces of the chest wall will lead to reduce all lung volumes. Arterial hypoxemia in these disorders is primarily caused by ventilation-perfusion ( V\Q mismatching). IV- Pathophysiology: In cases of extrinsic disorders of the pleura and thoracic cage, the total compliance of the respiratory system is reduced and hence, lung volumes are reduced. As a result atelectasis will occur and so gas distribution becomes nonuniform, resulting in (V\Q)mismatch and hypoxemia. - V- Diagnosis: A-History: - Occupational -Drug history -Family history history B-Clinical Presentation: Symptoms exertional dyspnea cough hemoptysis Chest pain physical findings (Signs): High-pitched rhonchi Cyanosis (advanced) Recurrent RTI Digital clubbing (IPF) They present to ICU with Respiratory Failure & arterial hypoxemia . C-Laboratory Studies: Anemia: vasculitis. Polycythemia: hypoxemia in advanced disease. Leukocytosis: acute hypersensitivity pneumonitis. Screen for collagen vascular disorders: - Antinuclear antibodies (ANA) and rheumatoid factor (RF). - Creatine kinase for polymyositis. ( CK ) - Antineutrophilic cytoplasmic antibodies (c-ANCA) for vasculitis. - Antiglomerular basement membrane antibody for Goodpasture’s syndrome. D- Imaging Studies: Intrinsic lung disorders: Chest radiography; Extensive bilateral reticulonodular opacities are seen in both lower lobes. High-resolution CT scanning of the chest The finding of honeycombing correlates with advanced fibrosis and indicates a poor prognosis. E-Other Tests: DLCO Flouroscopy BAL Biopsy PFTs Pulmonary function tests: The diagnosis of restriction is based on a decreased TLC. ( TLC) The assessment of the severity of restriction is also based on TLC. preserved or increased FEV1 ∕ FVC ratio suggests a restrictive pattern. ( or FEV1 ∕ FVC) A patient with emphysema has much higher lung compliance compared to a patient with intrinsic lung disease. -In nonmuscular diseases of the chest wall e.g. severe kyphoscoliosis produces a restrictive pattern, The TLC is markedly reduced. ( TLC ) vital capacity is reduced with relative preservation of the RV (residual volume) thus, RV-to-TLC ratio is elevated. ( RV ∕TLC ) Maximal inspiratory and expiratory pressures are decreased. ( MIP & MEP ) The diffusing capacity of lung for carbon monoxide (DLCO) : DLCO is the most sensitive parameter, and findings may be abnormal even when the lung volumes are preserved. A normal DLCO value excludes intrinsic lung disease and indicates a chest wall, pleural, or neuromuscular cause of restrictive lung disease. sis Bronchoalveolar lavage : Performing BAL lymphocytosis in patients with IPF may help predict steroid responsiveness. A predominance of T-lymphocytes with an elevated CD4-to-CD8 ratio is characteristic but not diagnostic of sarcoidosis. BAL fluid may contain malignant cells, asbestos bodies, eosinophils, and hemosiderin macrophages, which assist in making a diagnosis. -Lung biopsy: may help lead to a specific diagnosis, assess for disease activity, exclude neoplastic and infectious processes and predict the outcome. Open lung biopsy can be as valuable in selected patients as high-resolution CT scanning. Diagnosis 1- Anemia 2-Polycythemia 3- Leukocytosis 4- Creatine Kinase 5- ANA, c-ANCA 6- Fluoroscopy Intrinsic Causes Extrinsic Causes ++++ ++ ++ _ ++++ _ ++ ++ ++ +++ _ +++ Diagnosis 7- TLC - FEV1 ∕ FVC - RV ∕ TLC 8- DLCO (Normal) 9- High resolution CT 10- BAL 11- Lung biopsy Intrinsic Causes Extrinsic Causes +++ +++ + _ ++++ ++++ ++++ +++ ++= +++ ++++ + (Infection) _ _ VI- Treatment A- Supportive therapy: Precipitating factors or complications. Supplemental oxygen therapy. In advanced disease, Mechanical ventilation; Invasive mechanical ventilation. noninvasive ventilation. Non Invasive ventilation is beneficial: -It helps relieve dyspnea and pulmonary hypertension. -improve RV and gas exchange. -Also, hospitalization rates are markedly reduced and activities of daily living are enhanced. Guidelines for ventilator settings in restricive lung disease: -Intrinsic lung disease: Choose a mode capable of supporting oxygenation & ventilation, such as PC or VC-CMV. No evidence to date that PV is superior to VV. Maintain SaO2 ≥ 88% to 90%. Apply a PEEP level that prevents alveolar collapse and overdistention to prevent lung damage. PEEP may allow reduction of FiO2 to safe level. Keep P plateau ‹ 30 cmH2O by lowering Vt to 4 to 6 ml\ Kg. Allow permissive necessary. If VV is selected, the descending flow waveform is of choice. hypercapnia if Extrinsic disorders: e.g. neuromuscular disease Full or partial support. Negative or positive pressure ventilation. Non invasive or invasive ventilation. VV, high Vt 12-15 ml\Kg, f= 8-12 breaths\min. Inspiratory flow rates ≥ 60L\ min to meet patient need (Ti about 1 sec. to start) Flow waveform: constant or descending ramp. PEEP= 5 cmH2O may be needed to releive dyspnea. B- Definitive (Medical): Treatment depends on the specific diagnosis, which is based on findings from the clinical evaluation, imaging studies, and lung biopsy. Corticosteroids, immunosuppressive agents (Azathioprine, cyclosporin, cyclophosphamide & methotrexate) are the mainstay of therapy for many of the interstitial lung diseases. Treatment of neuromuscular diseases includes: - preventive therapies according to VC & MIP. - Plasmaphresis.. - IVIG. - Corticosteroids (early ?) - Immunosuppressive agents. Management for obesity (BMI≥40) . Lung Transplantation: The prognosis for patients with IPF who do not respond to medical therapy is poor; usually die within 2 - 3 years. These and other patients with severe functional impairment, oxygen dependency, and a deteriorating course should be listed for lung transplantation. Key Messages The natural history of interstitial lung diseases is variable. It depends on the specific diagnosis, the extent and severity of lung involvement based on high-resolution CT scanning and lung biopsy. IPF is typically progressive disorder, and patients have a mean survival of 3-6 years after diagnosis. Early recognition of IPF is important for directing patient management and predicting prognosis. Patients with IPF who do not respond to medical therapy; usually die within 2-3 years. Patients with severe functional impairment, oxygen dependency, and a deteriorating course should be listed for lung transplantation. Pulmonary sarcoidosis has a relatively benign self-limiting course, with spontaneous recovery or stabilization in most cases. Approximately 15% of patients develop pulmonary fibrosis and disability. Prognosis for collagen-vascular diseases, eosinophilic pneumonia and drug-induced lung disease is generally favorable with treatment. Patients with chest wall diseases and neuromuscular disorders develop progressive respiratory failure and an intercurrent pulmonary infection. Mechanical ventilation settings are not the same for all patients suffering restrictive lung diseases , however it is tailored according to patient response for both medical & supportive therapies.