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Multiple sclerosis, myasthenia gravis and Guillain–Barré: breathing watch, fatigue and crises

  • Assessment

In Guillain–Barré and myasthenia gravis the breathing muscles can fail within hours: the nurse checks breathing strength and swallowing often and calls early.

Updated

What it is

These conditions weaken muscles in different ways, but the nursing danger is shared: weakness of the breathing and swallowing muscles. In Guillain–Barré syndrome, weakness usually starts in the legs and climbs, sometimes over hours, and the nerves that control blood pressure and heart rate can be affected. In myasthenia gravis, weakness gets worse with activity and better with rest; a myasthenic crisis is a sudden weakness of the breathing muscles. In multiple sclerosis, attacks come and go, and fatigue, heat, bladder problems and falls are the daily issues. The nurse measures breathing strength as ordered, watches swallowing and speech, monitors heart rate and blood pressure, prevents clots, pressure injuries and aspiration, and paces activity.

Reference values

  • In Guillain–Barré, vital capacity is measured every 2 to 4 hours while weakness is worsening and every 6 to 12 hours once stable (as ordered); a falling trend is reported.
  • Bedside signs of breathing weakness: weak cough, single-breath count falling, weak neck flexion, paradoxical abdominal movement.
  • Measurements of breathing strength can be falsely reassuring when facial or swallowing weakness prevents a good seal.
  • About one in five patients with Guillain–Barré have problems with blood pressure and heart rhythm, including slow heart rates, even if they can walk.
  • In myasthenia gravis, too much or too little medicine, stress and heat can bring on weakness; a crisis may need breathing support.

What you need

  • The equipment for the ordered breathing-strength measurement (such as a spirometer) and a record of the trend.
  • Pulse oximeter, cardiac monitor if ordered, blood-pressure cuff.
  • Suction at the bedside; swallow-screening tool.

How to measure it (and why)

  1. Measure breathing strength at the ordered interval and plot the trend: a falling trend is reported at once.
  2. Ask the patient to count aloud on one breath and to cough; watch the neck and belly as they breathe: weak muscles show first.
  3. Do not rely on oxygen saturation alone: use the breathing-strength trend and the bedside signs as well.
  4. Check swallowing, voice and drooling before every meal: bulbar weakness leads to aspiration.
  5. Check heart rate, rhythm and blood pressure, lying and standing when allowed: nerves to the heart and vessels may fail.
  6. Check bladder emptying and bowel sounds: retention and ileus can occur.
  7. Turn, protect the skin, apply clot prevention as ordered and position limbs to avoid contractures: immobility harms.
  8. Plan rest between activities, keep the room cool and avoid fatigue: weakness worsens with effort and heat.
  9. Ask about pain, sleep and mood: pain is common in Guillain–Barré.

How to read it

  • A falling trend in breathing strength over hours matters more than one value.
  • In myasthenia, weakness that improves after rest is the expected pattern; weakness at rest, with trouble breathing or swallowing, is a crisis.
  • In multiple sclerosis, new or worsening symptoms (vision, weakness, numbness) are reported; fever, heat and stress can trigger or worsen them.
  • Guillain–Barré: the progressive phase is the most dangerous; patients are watched closely until weakness stops getting worse.

Next step: when to call for help

  • Call at once: trouble breathing or taking a deep breath, weak cough, falling breathing-strength values, choking, drooling, unable to swallow.
  • Call at once: weakness that is spreading or getting worse, fainting, a very slow or irregular pulse, very high or low blood pressure.
  • Report: urinary retention, abdominal swelling with no bowel sounds, a new pressure sore, a swollen calf.
  • Myasthenia: report any new medicine order to the prescriber or pharmacist before giving it, because some medicines worsen weakness.

Test yourself

Think of the answer, then tap the question to see it.

Why is breathing strength measured repeatedly in Guillain–Barré?

Weakness can climb within hours. While it worsens, vital capacity is measured every 2 to 4 hours as ordered, and a falling trend is reported at once.

Which three bedside signs show that the breathing muscles are weakening?

A weak cough, a falling count on one breath, using the neck muscles to breathe, or the belly moving inward on breathing in.

How does weakness typically behave in myasthenia gravis?

It gets worse with activity and better with rest. Eyelid drooping and double vision are often first; breathing or swallowing trouble is an emergency.

What can make multiple sclerosis symptoms worse?

Fever, hot baths, sun exposure, stress and fatigue. Rest periods and avoiding heat help.

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Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: Acute management of Guillain-Barré syndrome: a narrative review (Archives of Internal Medicine Research (Cameron A, Agrawal DK), PubMed Central, 2026); Guillain-Barré syndrome (Medical Encyclopedia) (MedlinePlus, U.S. National Library of Medicine, 2024); Myasthenia gravis (Medical Encyclopedia) (MedlinePlus, U.S. National Library of Medicine, 2024); Multiple sclerosis (Medical Encyclopedia) (MedlinePlus, U.S. National Library of Medicine, 2024).

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