Asthma and Impaired Gas Exchange

  1. Hi everyone,
    I have no idea if this is the right place to put this question so hopefully it is!
    I have an assessment for uni (I'm first year BN student) due in 10 days in which I have to do a care plan for a lady who's been admitted to hospital suffering an asthma attack that has been exacerbated by an URTI. We have to concentrate on the nursing diagnosis of "Impaired gas exchange" but I just can't seem to find an explanation of how gas exchange is impaired during an exacerbation of asthma. The only explanations I've found are way too detailed for me to understand, and anything else doesn't go into ENOUGH detail.
    Can someone PLEASE explain it to me? I'm getting desperate.
  2. Visit Smurfie profile page

    About Smurfie

    Joined: May '08; Posts: 14


  3. by   GingerSue
    - air trapping in the bronchioles
    - bronchospasm resulting from constriction of bronchial smooth muscle
    - inflammation and edema of the mucous membrane and subsequent accumulation of thick secretions in the airways - airways become narrow and there can be obstruction, air flows more easily into areas with the least resistance and the blood that does flow to the less ventilated portions of the lungs is not adequately saturated with oxygen. Mismatch of ventilation and perfusion in the poorly ventilated areas of the lung occurs and this results in incompletely saturated blood entering the systemic circulation and decreased PO2 levels [hypoxia]
  4. by   Smurfie
    Thank you so much for the quick answer! So it's just a matter of where the most bronchoconstriction and mucus accumulation is that determines which alveoli will have adequate air supply. Gosh I've been googling and searching journals for the last 2 days on and off and just kept getting myself more and more confused.
  5. by   GingerSue
    and as this child tries to get enough air, then their respiratory rate increases - so this tachypnea lowers carbon dioxide levels in the blood (hypocapnia).
    Because of the increased work of breathing, the child will tire - so hypoventilation occurs and the carbon dioxide levels increase.
    The hypercapnia during an asthma episode may be a sign of impending respiratory failure.
  6. by   Daytonite
    the first thing you should be doing to understand this diagnosis is to start by looking at the nanda information about it from the taxonomy. nanda provides you with the information you need to know. this information will be in a nursing diagnosis reference book or possibly a care plan book. it is posted right below the title of the diagnosis on this webpage: [color=#3366ff]impaired gas exchange. the definition of the diagnosis is the true problem that describes it: excess or deficit in oxygenation and/or carbon dioxide elimination at the alveolar-capillary membrane (pg. 94, nanda-i nursing diagnoses: definitions & classification 2007-2008). that means the problem is meant to be dealing with situations occurring in the alveoli of the lung. recall from anatomy that the alveoli are the terminal elastic, thin-walled air sacs of the lungs surrounded by tiny capillaries which is where carbon dioxide and oxygen are actually exchanged during respiration. if you look further at the nanda information for this diagnosis you will find that there are only two related factors, or causes, for this situation to occur. they are
    • alveolar-capillary membrane changes
      • not as confusing as it sounds, it quite simply means that the membrane, or tissue, that separates the wall of the air sac (alveoli) and the capillary (vessel) walls has changed from it's normal anatomical structure and has become abnormal, or pathological, because there is disease present. this occurs in lung conditions such as one of the copds, fibrosis, tb, invasive cancer and others where permanent damage to the alveoli take place that is not reversible resulting in loss of valuable surface area that is used for oxygen/carbon dioxide gas exchange
    • ventilation perfusion imbalance
      • what this means is that an imbalance between oxygen and carbon dioxide exchange exists and there is either more oxygen or more carbon dioxide being exchanged than is normally supposed to occur. the usual reason for this is some sort of temporary blockage at the level of the alveoli. do not make the mistake of diagnosing a blockage in the bronchioles as being responsible for impaired gas exchange because oxygen and carbon dioxide are not exchanged in the blood vessels of the bronchi. ventilation perfusion imbalances occur when the alveoli are clogged with debris, exudates or built up sputum as in pneumonia, congestive heart failure or atelectasis following surgery.
    now, in order to choose any diagnosis, a patient must have specific signs and symptoms of that diagnosis. you discover those symptoms by doing an assessment of the patient. but, what are the signs and symptoms of impaired gas exchange you might ask? what signs and symptoms do you look for when you do your assessment? here again, the nanda taxonomy can help you. the taxonomy for this diagnosis lists the defining characteristics (nanda language for signs and symptoms) for impaired gas exchange. you will also find them listed on the weblink i provided for you, but i am going to list them here from my same reference i quoted above:
    • abnormal arterial blood gases
    • abnormal arterial ph
    • abnormal breathing (rate, rhythm, depth)
    • abnormal skin color (pale, dusky)
    • confusion
    • cyanosis (in neonates only)
    • decreased carbon dioxide
    • diaphoresis
    • dyspnea
    • headache upon awakening
    • hypercapnia
    • hypercarbia
    • hypoxemia
    • hypoxia
    • irritability
    • nasal flaring
    • restlessness
    • somnolence
    • tachycardia
    • visual disturbances
    now, your patient has asthma and an upper respiratory track infection. what do you know about the pathophysiology of asthma? it is a reversible airway obstruction due to bronchospasms that results in increased mucus secretions and edema of the respiratory mucosa. the inflammatory response is running amok and gunk (my term for sputum) builds up in the alveoli as fast as the patient can cough it out. this creates a ventilation perfusion imbalance. there is dyspnea, diaphoresis, tachycardia, cyanosis and confusion sometimes along with other symptoms. those are 5 defining characteristics of impaired gas exchange. it gives you the diagnostic statement of impaired gas exchange related to ventilation perfusion imbalance due to asthma and urti as evidenced by dyspnea, diaphoresis, tachycardia, cyanosis and confusion. other symptoms of asthma, which i did not list so as not to confuse you, will point the way to another respiratory nursing diagnosis.

    to find more information about asthma and it's pathophysiology, signs, symptoms and treatment, see the links on this thread:
    this thread contains the pathophysiology of the inflammatory response, something you will need to know again and again when any medical diagnosis with an "-itis" shows up.
    hope that answers your questions and gets you started on your assessment and care plan. there is information on constructing care plans on this thread:
  7. by   Smurfie
    Thank you! What fantastic info you've given me!

    I have one other problem that I can't figure out. I've looked up the meaning of hypercarbia (more than the normal level of CO2 in the blood), but then 'Impaired Gas Exchange' also has 'decreased carbon dioxide' as a clinical sign. Am I missing something? How can it be both?
  8. by   Smurfie
    Oh also, aren't hypercapnia and hypercarbia the same thing?
  9. by   PageRespiratory!
    Quote from Smurfie
    Thank you! What fantastic info you've given me!

    I have one other problem that I can't figure out. I've looked up the meaning of hypercarbia (more than the normal level of CO2 in the blood), but then 'Impaired Gas Exchange' also has 'decreased carbon dioxide' as a clinical sign. Am I missing something? How can it be both?
    Pt's will often hyperventilate because they are hypoxic (impaired exchange) CO2 is about 1000 times more diffusable than O2, so while the Pt may be hypoxic, ventilation may be occuring normaly.

    Oxygenation does not equal ventilation
    Tachypnea does not equal hyperventilation
    Hypercapnea = Hypercarbia = Hypoventilation = increased CO2
    CO2 is the ONLY measure of ventilation
    Last edit by PageRespiratory! on May 11, '08 : Reason: typo
  10. by   Daytonite
    Quote from smurfie
    thank you! what fantastic info you've given me!

    i have one other problem that i can't figure out. i've looked up the meaning of hypercarbia (more than the normal level of co2 in the blood), but then 'impaired gas exchange' also has 'decreased carbon dioxide' as a clinical sign. am i missing something? how can it be both?
    it can't be both.

    the definition of this problem is
    excessor deficit in oxygenation and/or carbon dioxide elimination at the alveolar-capillary membrane.
    you must read the definitions of these diagnoses carefully. too often people think the real nursing diagnosis is that 3 or 4 word label, i.e. impaired gas exchange. that is so-o-o wrong. the true patient problem is what is stated in the definition. you have to start reading the definitions of these nursing diagnoses to get the true picture and understanding of the problem. and, wouldn't you rather understand the reason you diagnosed the problem correctly than just be guessing that you pegged it right? also, keep in mind that you are looking at nanda taxonomy information and it's purpose is to cover a wide variety of situations with this problem, not just patients who have asthma. i keep telling people that nanda has done a lot of the legwork for you on the assessment and pathophysiologic clues for the physiological related diagnoses, but many don't want to believe me. want to know the symptoms of dehydration? look at the defining characteristics of deficient fluid volume. you have to look at a bigger picture. defining characteristics for impaired gas exchange are including all of the symptoms that are a result of
    • an excess in oxygenation in the alveoli
    • a deficit in oxygenation in the alveoli
    • an excess of carbon dioxide being eliminated from the alveoli
    • a deficit of carbon dioxide being eliminated from the alveoli
    there is no way that all 4 of those conditions can exist at the same time! this is where your knowledge of physiology and what is going on with the patient at a pathophysiological level is critical (as in critical thinking).

    what nanda has done is just conveniently listed all the symptoms that the patient could have that fit those four scenarios and alphabetized them into a list for us. it is for us, however, to know which symptoms belong with which situation, assess our patients and determine which of these symptoms exists. something you might do is make a notation next to each of the defining symptoms categorizing it as to whether it is a symptom of an excess or deficit of oxygenation or an excess or deficit of carbon dioxide elimination. this, of course, presumes you are starting your own little notebook of nursing diagnoses or using a nursing diagnosis reference. my copy of nanda-i nursing diagnoses: definitions & classification 2007-2008 has notes scribbled all over in it. in fact, i have a whole bunch of stuff noted on the page for this particular diagnosis. a reference is no good to you unless you make use of it.

    your patient must have at least one of the defining characteristics in order for you to be able to choose that diagnosis for him. to illustrate this for you i took 5 symptoms of the medical diagnosis of asthma (dyspnea, diaphoresis, tachycardia, cyanosis and confusion) and wanted you to see that those are also 5 defining characteristics that are evidence supporting using impaired gas exchange which means that a hypothetical patient with the medical diagnosis of asthma also has the nursing diagnosis of impaired gas exchange. in fact, i have no idea what your patient's symptoms actually were since you didn't mention them.

    does that clarify things for you?