Asthma: Diagnosis (Pediatric Nursing)

00:01 A diagnosis of asthma can sometimes go beyond symptoms, such as coughing, chest tightness, wheezing, and dyspnea.

00:08 It can go even beyond those signs and symptoms that worsen at night and improve with treatment.

00:13 Diagnosis may require certain tests, including pulmonary function tests, or PFTs, and peak expiratory flow, or PEF measurements.

00:22 Asthma symptoms can be reversed by rapid-acting beta agonist, such as albuterol, and they can be measured by spirometry.

00:29 A bronchial challenge test is a medical test used to assist in the diagnosis of asthma.

00:35 So, pulmonary function tests.

00:36 These are also known as spirometry, and these measure the airflow and the lung volumes during a forced expiratory maneuver from full inspiration.

00:44 Spirometry can help the clinician assess lung function by measuring the total volume of air that the patient can expel from the lungs after a maximal inhalation.

00:53 And it can also be used to see if airway constriction can be reversed, and this is called reversibility testing.

01:00 Think of an 8-lane highway that's being squished down and reduced into 4 lanes due to road construction.

01:06 The traffic is going to take a lot longer to travel through that stretch of highway.

01:09 In the same way, if your airway is narrower and narrower and narrower than normal, it will take you longer to empty your lungs of air.

01:17 It can also compare that result to how much air you breathed out altogether, and this ratio tells how much your airways are blocked.

01:24 So, asthma, it's an obstructive breathing disorder.

01:27 This means that the air flows out of your lungs more slowly than it should.

01:32 The patients will wear a nose clip to control their nasal air movement.

01:36 And this spirometry is going to record the entire breathing loop; the inspiration and the expiration.

01:42 And again, this is useful for reversibility testing.

01:45 Usually, medication is more effective if you have asthma because the airways are going to react to the medication.

01:53 In pulmonary function testing, we're looking at a few different values.

01:56 The first is the forced vital capacity, or the FVC.

02:00 This is the volume of air which is forcibly and maximally exhaled out of the lungs after taking the deepest breath possible.

02:07 The next is the forced expiratory volume in 1 second, or the FEV1.

02:12 And this is the volume of air which can be forcibly exhaled from the lungs in the first second of a forced expiratory maneuver.

02:19 The last is a ratio and this indicates what percentage of the total FVC is expelled from the lungs during the first second of total forced exhalation.

02:29 Now, let's talk about peak expiratory flow tests, also known as peak flows.

02:34 A peak flow meter is an inexpensive, portable, handheld device for those with asthma that is used to measure how well the air moves in and out of the lungs.

02:43 This measure is called a peak expiratory flow.

02:46 If a patient tracks their peak flows every day at the same time every day, the tool can be really useful to predict when a narrowing might be happening or a prodrome.

02:56 Sometimes, this can happen hours or days before their asthma symptoms present and a patient can be proactive about their treatment measures.

03:04 Usually, a patient will measure their peak flow at least once a day, usually in the morning before they take their asthma medications.

03:10 To perform this test well and consistently, the patient needs to have good and consistent technique.

03:16 Before the patient blows into the meter, they will want to be able to fully expand their chest cavity, so they need to stand up.

03:23 Next, they'll take a full deep breath.

03:27 They'll close their lips around the mouthpiece and blow out hard and fast in a single blow.

03:32 Now, in a patient with asthma, this can really trigger a cough and assure your patient that's okay.

03:36 They can recover between the attempts.

03:39 Your patient's going to repeat this about 3 times and record the highest number and that's the peak flow that they're going to use for that day.

03:46 Finally, let's talk about the bronchial challenge test.

03:49 This is where the clinician tries to see if they can cause an asthma attack in a patient, and this can assist in the diagnosis.

03:57 During this test, the patient is going to breathe in nebulized methacoline or histamine.

04:02 So this test can be called a methacoline challenge or a histamine challenge.

04:06 In a controlled clinical environment, the patient's going to inhale methacoline aerosols in increasing concentrations.

04:12 Various protocols can be used.

04:14 Spirometry is performed before and after each dose, and the results are reported as a decrease in FEV1 from baseline for each step of the protocol.

04:24 Methacoline is going to irritate the airway and cause a narrowing in susceptible people.

04:28 And this can cause a severe bronchoconstriction, hyperinflation, and severe coughing.

04:34 The patient's airway is basically being forced into an asthma attack.

04:39 The challenge is considered positive if the methacoline causes a 20% or greater decrease in the patient's breathing ability when compared to their baseline.

04:47 A positive test suggests that the airways are reactive and a diagnosis of asthma should be considered.

04:53 A negative test means the diagnosis of asthma is unlikely.

04:57 The procedure is generally well-tolerated and respiratory symptoms in patients who react to the methacoline typically reverse promptly in response to bronchodilators.

05:06 While, this is a pretty common test, it should be performed in a setting equipped to deal with acute bronchospasm, and with personnel trained in resuscitation.

05:14 Informed consent should be obtained and recorded in the medical record after a detailed explanation of the risks and benefits of this procedure are discussed.