Sketchy Path: COPD and Emphysema

Question 1

COPD results from ________________.

Answer 1

irreversible damage to the alveoli that prevents air from escaping (like the guy who can’t drive out of the street with the “No U Turn” sign ahead of him)

Question 2

The paths between alveoli are called _____________.

Answer 2

alveolar ducts

Question 3

Which parts of the airways are affected in emphysema and chronic bronchitis?

Answer 3

• Emphysema: the alveoli, alveolar ducts, and respiratory bronchioles (like the pink-puffer hockey player in the alveoli cul-de-sac)
• Chronic bronchitis: terminal, bronchioles, proximal bronchioles, and bronchi (like the blue-bloater in the street next to the “Road Terminates” sign)

Question 4

Centriacinar emphysema typically affects which part of the lungs?

Answer 4

The upper two-thirds (like how the pink-puffer’s shirt is pale on the top two-thirds; he’s sitting near the respiratory bronchiole, so he represents centriacinar emphysema)

Question 5

Why does cigarette smoking cause emphysema?

Answer 5

Cigarette smoke has toxins (represented by hockey pucks) that induce a neutrophil response (represented by the EMTs rushing to the injured hockey player) that release elastase that damages tissues (represented by the EMT cutting the ELASTIC bandage around the injured player).

Question 6

Why does destruction of elastin cause obstructive lung disease?

Answer 6

The increased compliance causes the respiratory bronchioles to become floppy and they can’t hold open during exhalation.

Question 7

Alpha-1 antitrypsin deficiency leads to ___________ emphysema.

Answer 7

pan acinar (like how the leaves from the AA TRimmer are around the entire cul-de-sac)

Question 8

Why does alpha-1 antitrypsin deficiency selectively damage the lower lobes?

Answer 8

Blood flow is greater in the lower lobes, so more neutrophils can get there and release elastase.

(Think of the landscaper’s shirt: it’s tattered on the bottom edge.)

Question 9

Alpha-1 antitrypsin deficiency leads to ____________ in the liver.

Answer 9

PAS-positive globules (like the PASS ballons stuck in the liver bush)

This is one of the most common causes of cirrhosis in young people.

Question 10

What can help clue you in to a diagnosis of AAT deficiency?

Answer 10

Early onset of COPD in a nonsmoker (like the young kid trimming the bush)

Question 11

What are signs and symptoms of emphysema?

Answer 11

• Dyspnea (pink-puffer who can’t catch his breath)
• Tripodding (he’s also leaning on his arm)
• Wheezing (crazed fan blowing on party favor)
• Purse-lip breathing (pink-puffer is pursing his lips)
• Prolonged expiration (looooong party favor)
• Weight loss (hockey player’s skinny arm)
• Pulsus paradoxus (like the other hockey player’s band shirt)

Question 12

What x-ray pattern is characteristic of emphysema?

Answer 12

Enlarged lungs –more than 10 posterior ribs visible – with a “vertical heart” from the lungs squishing it

(The parachute has the classic pattern on it.)

Question 13

What auscultatory findings are common in emphysema?

Answer 13

• Distant heart sounds (like the heart balloons waaaay in the distance)
• Diminished lung sounds (like the lung sails waaaaay far back)

Question 14

What spirometry findings are typical of emphysema?

Answer 14

• Increased TLC
• Increased RV
• Decreased FEV/FVC

(Think of the bursting-to-the-seams bags of leaves labeled TLC and RV; also, the fan with the “ForEVer #1” and “ForeVer Champs” posters is being knocked over.)

Question 15

What FEV/FVC value is diagnostic of obstructive lung disease?

Answer 15

Less than 0.7 (like the puck dot and the 7-shaped stick)

Question 16

How does COPD affect DLCO?

Answer 16

COPD decreases DLCO.

(Think of the trash on the ground. Because CO is a colorless, odorless gas, Sketchy depicts DLCO as clear plastic garbage. Being on the ground means low DLCO.)

Question 17

Describe the metabolic complications that can develop in COPD.

Answer 17

• Early on, people usually hyperventilate to maintain PaO2. This can cause respiratory alkalosis. (The woman hyperventilating to blow bubbles through the OH bubble wand represents this.)
• Later, air trapping prevents ventilation and people develop respiratory acidosis with hypoxemia. (The newly passed out pink-puffer represents this state – notice that he’s below where the woman’s bubbles have popped.)

Question 18

What symptoms are diagnostic of chronic bronchitis?

Answer 18

A productive cough for more than three months over the last two years (like the blue-bloater hacking up green goo; his jersey is #32!)

Question 19

Why are those with chronic bronchitis COPD more likely to have respiratory acidosis early?

Answer 19

The mucus plugs the lower airways and traps CO2 (like the green goo on the bottles that are blocking the car and causing the exhaust to accumulate).

Note: this is also why those with CB are more likely to be hypoxemic –hence the blue in blue-bloaters!

Question 20

Explain the phenomenon of hyperoxia-induced hypercapnia.

Answer 20

In healthy people, the respiratory drive is driven primarily by PaCO2 sensors in the carotid bodies and aortic arch. Chronic respiratory acidosis desensitizes these receptors and causes the body to switch to PaO2 sensors for respiratory drive; when PaO2 is low, the respiratory drive increases ventilation.

Giving supplemental oxygen to a blue-bloater can signal the PaO2 receptors to slow ventilation and thus induce hypercapnia!

(Think of the blue-bloater getting O2 and knocking into the “Reduced Rate” sign.)

Question 21

How does COPD affect the heart?

Answer 21

Hypoxemia induces vasoconstriction that causes PAH (like the blue-bloater stretching the red fibers of the goal). This can cause right-heart failure –cor pulmonale (like the hockey player hitting the heart with a CORk in it).