Respiratory Stimulants and COPD

Respiratory stimulants help increase the urge to breathe

woman with difficulty breathing demonstrating need for respiratory stimulants
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A respiratory stimulant is primarily used in addition to noninvasive ventilation as a means to help increase the urge to breathe. It works by stimulating the central nervous system, resulting in an increase in respiratory rate and tidal volume, which is the amount of air that is inhaled or exhaled during a normal breath.

Patients with a chronic obstructive pulmonary disease, or COPD, are often treated with respiratory stimulants.

Here is what they are, how they work and what you need to know:

How Are Respiratory Stimulants Used?

Respiratory stimulants are used in four primary ways:

  • Respiratory failure
  • Apnea of prematurity (apnea and bradypnea spells)
  • To antagonize the effects of general anesthetics
  • To treat barbiturate poisoning

How Do Respiratory Stimulants Work?

Medications classified as airway stimulants that may be used with COPD include:

  • Theophylline is a bronchodilator (dilating the large airways of the lungs) that works by relaxing smooth muscle in the bronchial tubes. This medication may be used for those with asthma or COPD, but is usually used as only a second or third-line option.
  • Caffeine is used in premature babies, especially those born before 30 or 31 weeks gestation, who have periods of slow breathing (bradypnea) and periods in which they stop breathing (apnea) also known as "A and B spells."
  • Doxofylline is a methylxanthine category medication and is related to theophylline and caffeine.
  • Doxapram (Dopram, Stimulex or Respiram) works by stimulating chemoreceptors (receptors that pick up substances traveling in the blood) on the carotid body in the neck. The carotid body, in turn, sends a signal to the breathing center in the brainstem, which in turn increases and deepens the respiratory rate.

    Respiratory Stimulants and COPD

    Theophylline has been used for asthma and COPD for over 80 years, although it is used much less frequently than in the past. It works primarily through its function in dilating airways, but may also reduce inflammation. 

    For people with asthma, theophylline tends to be used for those who have nighttime persistent asthma.  It can help with asthma by reversing the constriction in airways. It is used in COPD to help reverse some of the diminished lung capacity associated with the disease.

    Respiratory Stimulants in Surgery and Overdoses

    Respiratory stimulants may also be used to counteract the effects of general anesthesia. In this setting, they help patients "come out of" the anesthesia. 

    This works in a similar way with overdoses in which patients may have taken an overdose of a medication which suppresses breathing (and for this reason can be fatal) by stimulating breathing at the level of the brain.

    Side Effects

    Respiratory stimulants are used less often than some other medications due to their tendency to cause side effects and interact with other medications.

    Theophylline and doxifyline are cousins of caffeine, and cause side effects similar to what you might expect after drinking several cups of coffee — jitteriness, anxiety, and a rapid heart rate. 

    People who use theophylline need to have their blood levels of the drug tested often to make sure enough drug is present to be effective, but not so high as to cause toxicity.  It's estimated that 35% of people on theophylline are started on medications with adverse interactions with theophylline, and therefore, other medications are usually preferable for this reason as well.

    Sources:

    Fragoso, C. Role of methylxanthines in the treatment of COPD. UpToDate. Updated 09/25/15. http://www.uptodate.com/contents/role-of-methylxanthines-in-the-treatment-of-copd

    Prins, S., Pans, S., van Weissenbruch, M. et al. Doxapram use for apnoea of prematurity in neonatal intensive care> International Journal of Pediatrics. 2013. 2013:251047.

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