62-year-old (male) with shortness of breath

00:02 A 62 year old man presents to the emergency department because of a 2-year history of increasing shortness of breath.

00:09 He also has had occasional nonproductive cough.

00:12 His symptoms get worse with exertion.

00:14 His medical history is significant for hypertension for which he takes chlorthalidone.

00:19 Of note, he is a smoker with a 40 pack year smoking history.

00:24 On physical examination, the patient is afebrile, blood pressure is 125/78, pulse is 90 respiratory rate is 18 and BMI is 31.

00:35 Oxygen saturation test on room air is 94%.

00:39 Pulmonary examination reveals decreased breath sounds bilaterally but is otherwise normal with no whezes or crackles.

00:47 The remainder of the examination in unremarkable.

00:50 Chest radiograph reveals hyperinflation of both lungs with mildly increased lung markings but no focal findings.

00:58 Based on this patient's clinical presentation, which of the following is most likely to be found in this patient? Answer choice (A) - FEV1 to FVC ratio of 65% Answer choice (B) - decreased total lung capacity Answer choice (C) - increased DLCO Answer choice (D) - metabolic acidosis and Answer choice (E) - FEV1 of 82% Now take a moment to come to the answer by yourself before we go through it together.

01:34 Now let's jump right in to this question.

01:36 Let's discuss the question characteristics.

01:38 Now this is a pathology question, we have someone who's smoking, with shortness of breath and cough, and is affecting the lungs.

01:44 So this is rspiratory pathology.

01:46 This is a 2-step question.

01:48 We have to determine the diagnosis of the patient and the lung function test result we would expect.

01:54 And the stem is absolutely required.

01:56 Not only get history but also get laboratory findings and radiograph findings to better understand the condition.

02:04 Now let's walk through this question together.

02:06 The first thing we need ot do is determine the likely diagnosis.

02:09 Now this patient's characteristic signs and symptoms are consistent with emphysema, a chronic obstructive pulmonary disease or COPD.

02:17 Now smoking is the leading cause of COPD and this patient has a significant smoking history of a 40-pack year smoking history which is very high.

02:27 Now let's refer to our image here of COPD, 2 subtypes of chronic bronchitis and emphysema to better understand the condition before we go through the rest of our answer walkthough and pick our answer to better understand this condition.

02:42 Now COPD has 2 subtypes - chronic bronchitis and emphysema.

02:47 Starting with chronic bronchitis, we can see an image there first of a healthy bronchi.

02:51 Now bronchitis breaks down to the word bronchi- which means the bronchioles or the airway and -itis which is inflammation and chronic is the chronicity of this event.

03:01 So in the healthy case, the airway is open and there is not much mucus.

03:05 below we see the case of chronic bronchitis in which we see inflammation and excess mucus production which is gonna lead to cough and difficulty expiring air.

03:15 Now on the right there, we see emphysema.

03:18 Now the image there of a healthy alveoli is often described as grapes on a vine, that's kind of what it looks like.

03:24 But below we see alveolar membranes break down in emphysema and we no longer have that nice delineation of the alveoli and we actually have a change in our total surface area leading to decreased gas transfer and also as we have breakdown of the alveolar membranes we actually have lots of recoil in our alveoli which also makes it difficult to expire air, both very important to understand this condition.

03:51 Now let's go back to step 2 of our walkthrough.

03:53 Now that we have determined this patient's condtion as COPD and we've reviewed the 2 clinical subtypes of COPD, let's determine the likely lung function test we would expect in this patient.

04:03 Now, COPD is characterized - this is very important, by a reduction in FEV1 by FVC ratio but it is important to understand why.

04:13 This reduction in the ratio is due to a reduced FEV1 which is due to compromised expiratory flow and that due to both inflammation, the increased mucus and also to the decreased lung recoil from alveolar membrane breakdown.

04:32 The patients will have a normal vital capacity, thus the numerator in this case will decrease while the denominator stay the same and thus the ratio is reduced overall.

04:44 Now in emphysem, the alveolar walls are destroyed which actually decreases the overall surface area for gas transfer and that will result in a decreased diffusion capacity or DLCO, not increased as it was noted in answer choice (C) so it is wrong.

04:59 And total lung capacity is increased in emphysema due to hyperinflation not decreased as noted in answer choice (B).

05:07 So the correct answer here is answer choice (A) FEV1 over FVC ratio of 65 percent, which is how we characterized COPD.

05:17 And we've also described the physiological background as to why vital capacity would stay the same in our forced expiratory volume over one interval will decrease.

05:29 Now let's review our high-yield facts regarding COPD.

05:32 And the leading cause of COPD is smoking .

05:35 And COPD as we've discussed has two subtypes - chronic bronchitis and emphysema.

05:40 Bothof these types of COPD are characterized by increased shortness of breath due to airways obstruction, with spirometry showing a reduced FEV1 to FVC ratio below 70% which is the lower limit of normal.

05:53 Now emphysema is characterizd by destrcution of alveolar walls with the loss of elastic recoil of the lungs resulting in hyperinflation and increased total lung capacity.

06:03 And chronic bronchitis is characterized by increase in mucus production and inflammation resulting in cough and total lung capacity is also increased.