# 073 Amyotrophic Lateral Sclerosist (ALS) Management of Respiratory Failure, 2nd ed

FAST FACTS AND CONCEPTS #073 PDF


Author(s): Ajmal Gilani MD, Albert Hinn MD, Peter Lars Jacobson MD

Background   Respiratory failure is the most common cause of death from amyotrophic lateral sclerosis (ALS). Except for rare patients who present with respiratory failure, respiratory muscle weakness develops insidiously during the course of the disease. This allows most patients, families, and clinicians time to carefully discuss the options for ventilatory support before such decisions needs to be made. Options for ventilatory support should be discussed long before the development of respiratory insufficiency. In addition, patients should be encouraged to identify a power of attorney for health care/healthcare proxy and to discuss their preferences about ventilatory support early in the course of the illness.

Assessment of Respiratory Insufficiency Early signs and symptoms of respiratory muscle weakness are subtle: dyspnea with mild exertion, supine dyspnea, insomnia, morning headache, reduced appetite, weight loss, dizziness, depression, anxiety and marked fatigue. There are no standard protocols 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 be used to 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, 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 use of oxygen at night without ventilatory assistance is not sufficient; patients with oxygen desaturation and chronic hypercapnia require nocturnal BiPAP ventilation 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 invasive ventilatory support is sometimes considered when non-invasive ventilation 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 with a 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 adequate advance care planning occurs.

Supportive Care 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 can be 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). Anxiety due to respiratory insufficiency can be treated with lorazepam (0.5-1.0 mg 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 about ventilator withdrawal.

References

  1. Bosario GD, Voltz R, Miller RG. Palliative care in amyotrophic lateral sclerosis. Neurologic Clinics. 2001; 19(4):801-827.
  2. Bradley WG, Daroff RB, et al. Neurology in Clinical Practice. Woburn, MA: Butterworth-Heinemann; 2000: pp2005-2014.
  3. Beach JR. Amyotrophic lateral sclerosis: predictors for prolongation of life by non-invasive respiratory aids. Archives of Physical Medicine and Rehabilitation. 1995; 76(9):828-32.
  4. Pinto AC, Evangelista T, Carvalho M. Respiratory assistance with a non-invasive ventilator (Bipap) in MND/ALS patients. J Neurological Sciences. 1995; 129(Suppl):S19-26.
  5. Howard RS, Wiles CM, Loh L. Respiratory complications and their management in motor neuron disease. Brain. 1989; 112(5):1155-70.
  6. Oliver D, Borasio GD, Walsh D. Palliative Care in Amyotrophic Lateral Sclerosis. New York, NY: Oxford University Press; 2000.
  7. Voltz R, Bernat JL, Borasio GD, Maddocks I, Oliver D, Portenoy RK. Palliative Care in Neurology. New York, NY: Oxford University Press; 2004: pp79-89.

Fast Facts and Concepts are edited by Drew A Rosielle MD, Palliative Care Center, Medical College of Wisconsin. For more information write to: drosiell@mcw.edu. More information, as well as the complete set of Fast Facts, are available at EPERC: www.eperc.mcw.edu.

Version History: This Fast Fact was originally edited by David E Weissman MD. 2nd Edition published July 2006. Current version re-copy-edited April 2009.

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Gilani A, Hinn A Jacobson PL. Management of Respiratory Failure in ALS, 2nd Edition. Fast Facts and Concepts. July 2006; 73. Available at: http://www.eperc.mcw.edu/EPERC/FastFactsIndex/ff_073.htm.

Disclaimer: Fast Facts and Concepts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Facts cite the use of a product in a 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.

ACGME Competencies: Medical Knowledge, Patient Care

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