Normal chest radiograph in terminal respiratory failure due to amyotrophic lateral sclerosis.

To the Editor: We report the case of a patient with terminal respiratory failure due to amyotrophic lateral sclerosis (ALS) who had a normal chest radiograph (CXR) 13 hours before respiratory arrest and death. This case shows that a normal CXR in the setting of severe neuromuscular disease cannot be used as evidence of even short term respiratory stability.

A 48-year-old man with end-stage ALS presented with respiratory insufficiency and weight loss. Five months before his admission, he lost the ability to ambulate without assistance and he developed progressive difficulty speaking and swallowing. He subsequently lost 50 pounds and became essentially bed bound.

His height was 73 inches and his weight was 120 pounds. His respiratory rate was 18 breaths per minute and breathing was mildly labored. Oxygen saturation by digital pulse oximetry was 97% while the patient was breathing ambient air. His speech was barely audible. His cough was weak and he was tetraparetic.

A bedside frontal chest radiograph demonstrated normal lung volumes and no cardiopulmonary abnormalities. Vital capacity measured at the bedside was 400 mL. On hospital Day 1, the patient's breathing became increasingly labored. He was placed on bi-level positive airway pressure ventilation, but his respiratory status deteriorated progressively. He developed obtundation and arrested. Per his directive, he was not resuscitated. He was pronounced dead as a result of respiratory failure 13 hours after a normal CXR.

Patients with ALS commonly die from pulmonary complications. (1) Common respiratory sequelae include atelectasis, pneumonia, copious secretions, aspiration, and obstructive sleep apnea. Chest radiographic abnormalities are frequent in end-stage ALS. Atelectasis is seen early in respiratory failure and often persists despite assisted ventilation. (2) Conversely, clinicians may be erroneously reassured by a normal CXR. To our knowledge, no study has correlated radiographic findings with the degree of respiratory muscle weakness or with the incidence of respiratory failure in ALS.

In conclusion, clinicians should not be reassured by normal chest radiographic findings when assessing a patient with ALS for possible respiratory insufficiency. Clinicians must assess other clinical indicators, including pulmonary function, symptoms and signs of respiratory insufficiency, as well as imaging studies when trying to diagnose and/or predict respiratory failure in patients with ALS. (3,4)

Christine Won, MD

Dipanjan Banerjee, MD

VA Palo Alto Health Care System and Stanford University

Palo Alto, CA

Paul Stark, MD

VA San Diego Health Care System and University of California 

San Diego, CA

Ware G. Kuschner, MD

VA Palo Alto Health Care System and Stanford University

Palo Alto, CA

References

1. Lechtzin N, Rothstein J, Clawson L, et al. Amyotrophic lateral sclerosis: evaluation and treatment of respiratory impairment. Amyotroph Lateral Scler Other Motor Neuron Disord 2002;3:5-13.

2. Schmidt-Nowara WW, Altman AR, Atelectasis and neuromuscular respiratory failure. Chest 1984;85:792-795.

3. Rabinstein AA. Wijdicks EF. Warning signs of imminent respiratory failure in neurological patients. Semin Neurol 2003;23:97-104.

4. Similowski T, Attali V, Bensimon G, et al. Diaphragmatic dysfunction and dyspnoea in amyotrophic lateral sclerosis. Eur Respir J 2000;15:332-337.

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