Accessory Muscle Use

  • When breathing requires extra effort, the accessory muscles—the sternocleidomastoid, scalene, pectoralis major, trapezius, internal intercostals, and abdominal muscles—stabilize the thorax during respiration.
  • Typically, the extent of accessory muscle use reflects the severity of the underlying cause.
  • However, more pronounced use of these muscles may signal acute respiratory distress, diaphragmatic weakness, or fatigue.
  • Quickly auscultate for abnormal, diminished, or absent breath sounds
  • Giving a patient with COPD too much oxygen may decrease his respiratory drive. An I.V. line may be required

History and Physical Examination Accessory Muscle Use

  • Ask about recent trauma, especially to the spine or chest. Find out if the patient has recently undergone pulmonary function tests or received respiratory therapy.
  • Explore the family history for such disorders as cystic fibrosis and neurofibromatosis, which can cause diffuse infiltrative lung disease.
  • If the patient’s condition allows, examine him more closely.
  • Ask him about the onset, duration, and severity of associated signs and symptoms, such as dyspnea, chest pain, cough, or fever.

Medical Cause’s Accessory Muscle Use

  • Acute respiratory distress syndrome (ARDS). In ARDS, a life-threatening disorder, accessory muscle use increases in response to hypoxia.
  • Amyotrophic lateral sclerosis. Typically, this progressive motor neuron disorder affects the diaphragm more than the accessory muscles.Other signs and symptoms include fasciculations, muscle atrophy and weakness, spasticity, bilateral Babinski’s reflex, and hyperactive deep tendon reflexes
  • Airway obstruction. Acute upper airway obstruction can be life-threatening
  • Asthma. During acute asthma attacks, the patient usually displays increased accessory muscle use.
  • Emphysema. Increased accessory muscle use occurs with progressive exertional dyspnea and a minimally productive cough
  • Chronic bronchitis. With chronic bronchitis, a form of COPD, increased accessory muscle use may be chronic and is preceded by a productive cough and exertional dyspnea.
  • Pneumonia. Bacterial pneumonia usually produces increased accessory muscle use. Initially, this infection produces a sudden high fever with chills
  • Thoracic injury. Increased accessory muscle use may occur, depending on the type and extent of injury

Diagnostic tests and treatments. Pulmonary function tests (PFTs), incentive spirometry

  • Because of age-related loss of elasticity in the rib cage, accessory muscle use may be part of the older person’s normal breathing pattern.



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