FAST FACT AND CONCEPT #73: Management of Respiratory Failure in ALS

2nd Edition

Authors: Ajmal Gilani , MD ; Albert Hinn, MD; Peter Lars Jacobson, MD

Respiratory failure is the most common cause of death from ALS. Except for rare patients who present with respiratory failure, respiratory muscle weakness develops insidiously during the course of the disease. Options for ventilatory support should be discussed long before the development of respiratory insufficiency. A power of attorney for health care should be obtained and/or healthcare proxy identified by the patient and family.

ASSESSMENT OF RESPIRATORY INSUFFICIENCY

Early signs and symptoms of respiratory muscle weakness are subtle: dyspnea w/ mild exertion, supine dyspnea, insomnia, morning headache, reduced appetite, weight loss, dizziness, depression, anxiety and marked fatigue. There are no standard tests to detect early respiratory failure. The following tests may be helpful:

Maximal Inspiratory Pressure (MIP) has been reported to be the single most sensitive test.

Measuring the change from erect to supine sitting Vital Capacity (VC) can detect early diaphragmatic weakness and can monitor declining respiratory function. Diaphragm weakness is suggested by a greater than 25% fall in VC on assuming a supine position. A normal supine VC makes significant inspiratory muscle weakness unlikely. A VC less than 1L or less than 30% of predicted value indicates significant risk of respiratory failure and death.

Nocturnal oximetry is useful in evaluating nocturnal hypoventilation; a full polysomnogram can be an alternative test.

CHOICES FOR RESPIRATORY MANAGEMENT

Bi-level Positive Airway Pressure (BiPAP), a type of Non Invasive Ventilation (NIV), can improve symptoms of hypoventilation, quality of life, and survival by several months. Some patients, particularly those with bulbar involvement and difficulty in clearing secretions, cannot tolerate BiPAP. The sole use of oxygen at night is not sufficient; patients with oxygen desaturation and chronic hypercapnia require nocturnal BiPAP machine to avoid suppression of respiratory drive during sleep. During the day BiPAP can be used to alleviate respiratory muscle fatigue. The use of Intermittent Positive Pressure breathing machines has been reported to expand the lungs and reduce atelectasis.

Full time ventilator support is sometimes considered when NIV is no longer effective or tolerable Treating reversible problems (e.g. acute respiratory infection) is important to avoid the need for invasive long-term ventilation w/ tracheostomy. Most patients who select a ventilator become completely dependent on it and are unable to communicate verbally. Many patients will choose not to be ventilated if comfort is assured and advance care planning occurs.

Regardless of assisted ventilatory choices, compassionate and effective palliative care must be implemented. A calm environment, the reassuring presence of relatives, trunk elevation and chest physiotherapy may all provide relief. The sensation of shortness of breathing is reduced by morphine (2.5-10 mg by mouth or 1-2 mg IV/subcutaneous every 1-4 hours). Titration of the morphine dose against the clinical effect almost never leads to a life threatening respiratory depression. (see Fast Fact #27 Dyspnea management) Anxiety due to respiratory insufficiency can be treated with lorazepam, (0.5-1.0) sublingually. When co-morbid medical complications develop, or patient determined quality of life deteriorates, ventilator support can be withdrawn and symptom control provided to allow for a comfortable death. See Fast Facts #33, 34, 35 Guidelines for Ventilator Withdrawal.

References:

1. Carver, Alan C., Foley, Kathleen M. Neurology Clinics, Palliative Care. W.B. Saunders Company: 2001;835-836.
2. Bradley, Walter G., Daroff, Robert B., Fenichel, Gerald M., Marsden, Davis C. Neurology in Clinical Practice Vol. II. Butterworh, Heinemann:2000;2005-2014.
3. Beach, JR. Amyotrophic lateral sclerosis: predictors for prolongation of life by non-invasive respiratory aids. Archives of Physical Medicine and Rehabilitation 01-Sep-1995; 76(9): 828-32.
4. Pinto AC, Evangelista T, Carvalho M. Respiratory assistance with a non-invasive ventilator (Bipap)00 in MND/ALS patients. Journal of the Neurological Sciences 01-May-1995;129 Suppl:19-26.
5. Howard, RS, Wiles, CM, Loh, L. Respiratory complications and their management in motor neuron disease. Brain 01-Oct-1989;112(5):1155-70.
6. Palliative Care in Amyotrophic Lateral Sclerosis. Oliver D, Borasio GD, Walsh D; Oxford University Press, 2000; 45.
7. Voltz R, Bernat JL, Borasio GD, Maddocks I, Oliver D, Portenoy RK. Palliative Care in Neurology. Oxford University Press, Oxford:2004;79-89.

Fast Facts were edited by David Weissman MD, Palliative Care Center, Medical College of Wisconsin until January 2007.  For comments/questions write to the current editor, Drew Rosielle MD: drosiell@mcw.edu. The complete set of Fast Facts is available at EPERC: www.eperc.mcw.edu

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing: Gilani, A, Hinn, A and Jacobson PL. Fast Facts and Concepts #73: Respiratory failure in ALS, 2 nd Edition. July 2006. End-of-Life / Palliative Education Resource Center: http://www.eperc.mcw.edu.

Disclaimer: Fast Facts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Fact information cites the use of a product in dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.

Creation Date: 7/2002

Purpose: Instructional Aid, Self-Study Guide, Teaching

Audience(s)

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Other neurologic disorders

Specific Disease and Organ System Category(s): Other neurological disorder