1191

Abstract

Introduction: 79 year old male presented with generalized weakness, slurred speech, altered mental status and labored breathing for several hours along with 20 pound weight loss over 6 months. Patient had three admissions at different hospital over the last 3 months for similar but milder presentation. Past work up included CT scan of the chest which was unrevealing and pulmonary function test (PFT) which showed restrictive lung disease with FEV1 of 48%, FVC of 44% of predicted and FEV1/FVC 84, though he was given the diagnosis of chronic obstructive pulmonary disease (COPD) as an explanation of his hyperbaric respiratory failure. Physical exam in the ED was pertinent for tachycardia, labored shallow breathing and lethargy. Auscultation of his chest demonstrated bilateral decreased breath sound. An arterial blood gas analysis showed pH of 7.04, PaCO2 of >130.00 mmHg and PaO2 of 218 mmHg on 100% oxygen. Chest x-ray and CT scan of the head were both unremarkable for acute process. Hypercarbia was initially attributed to possible COPD and obstructive sleep apnea (OSA). Patient's trachea immediately intubated and mechanical ventilation was begun. After borderline spontaneous breathing trial, patient was extubated next morning. Patient required bi-level noninvasive positive pressure mechanical ventilation (NIPPV) for moderate respiratory distress after extubation. A repeat physical examination was remarkable for impaired dorsiflexion of right ankle, tongue fasciculation and weak negative inspiratory force. There was no evidence of upper motor neuron dysfunction. Work up for neuromuscular weakness included antiacetylcholine receptor antibody, which was negative and electromyography, which demonstrated 2+ fasciculation and fibrillation potentials in >3 muscle groups. A diagnosis of progressive muscular atrophy (PMA) with early respiratory failure was made; it is believed to be a rare form of Amyotrophic Lateral Sclerosis (ALS). After discussing the merits and demerits of invasive mechanical ventilation via tracheostomy and gastrostomy tube insertion, he opted for comfort care. ALS is a neurodegenerative disease characterized by progressive muscular paralysis due to degeneration of lower and upper motor neurons in the primary motor cortex, brainstem, and spinal cord. Muscular paralysis is progressive and typically leads to death due to respiratory failure within 2-5 years of onset. However, only 3.0% of patients with ALS present with respiratory symptoms and 14% of this subpopulation requires mechanical respiratory support, a rare presentation of ALS. Clinical features of early respiratory failure like dyspnea on minor exertion, early morning headache, daytime fatigue and weight loss may be subtle and often overlooked. The classic form of ALS presents with both upper motor neuron (UMN) and lower motor neuron (LMN) findings, but it can be as in our case limited to LMN only and is referred to as PMA. Compared to ALS, patients with PMA are more likely to be males and live longer. Management of ALS in all of its forms is supportive, multidisciplinary and palliative. Early use of NIPPV in ALS patients prolong survival and improve quality of life. Invasive mechanical ventilation, implying the use of an endotracheal tube or a tracheostomy may be considered. Patient with bulbar dysfunction may need gastrostomy to support nutrition. A FVC of <50% of the predicted value has been shown to be associated with poor prognosis. Arriving to accurate diagnosis in timely manner is critical for health care team to expedited discussion with patient and family about management plan and encourage them to consider advanced directives regarding end of life. Patients should be provided with a realistic prognostication of the course of their disease and in the event of decline of full mechanical ventilation, patient and family should be provided with assurance that palliative care strategies can control symptoms in the terminal phase of illness.