SIMPLE 28: Dyspnea/COPD

Question 1

85% of pts p/w dyspnea have one of these conditions

Answer 1

Asthma, CHF, COPD, PNA, cardiac ischemia, ILD, and psychogenic causes (You can dx w/ hx alone in 50%; or w/ H&P + CXR in 81%)

Question 2

pulsus paradoxus

Answer 2

decr in BP of > 25 mmHg w/ inspiration

Question 3

When is BNP likely falsely high?

Answer 3

BNP is excreted by the kidneys, so will be elevated in patients with renal failure

Question 4

BNP

Answer 4

.

Question 5

AST & ALT ref ranges

Answer 5

Appx

Question 6

List Three reasons why pts with COPD do worse when you treat their hypoxia only?

Answer 6

1. Haldane effect - oxygenated Hgb has reduced CO2 carrying capacity
2. V/Q mismatch - pulm BVs that constrict d/t hypoxia dilate in response to O2 tx and begin to perfuse poorly ventilated lung causing reduced clearance of CO2
3. Resp drive - COPD pts w/ chronic CO2 elev may depend more on hypoxia sensors to drive respiration rather than typical CO2 sensors. When hypoxia is corrected they lose the hypoxic resp drive on which they have been relying and CO2 levels climb.

Question 7

Indications for BiPAP (or other NIPPV) in COPD exacerbation?

Answer 7

severe resp acidosis (pH45) or hypoxia that persists despite maximal supplemental O2

Question 8

Brief ABG interpretation steps

Answer 8

1. look at pH and ask “acidosis or alkalosis?”
   2a. look at bicarb and ask “metab or resp?”
   2b. if acidosis, check GAP ask “AG acidosis or no?”
   3a. Resp comp for metab alk: CO2 should = last two pH digits (or use Winter’s formula: CO2 = [1.5 x HCO3] + 8)
   3b. Metab compensation for resp acidosis: HCO3 ↑:
   - 1 mEq/L : 10 mmHg rise in CO2 if ACUTE
   - 4 mEq/L : 10 mmHg if CHRONIC

Question 9

17 hrs of O2 a day has been shown to decrease mortality in COPD pts meeting these criteria:

Answer 9

PaO2 ≤55 or SaO2 55%; OR sleep or exertion-related de-sat

Question 10

FEV1:FVC ratio

Answer 10

Obstructive picture

Question 11

FVC

Answer 11

Restrictive picture (Rarely “pseudo-restriction” can occur, meaning the reduced FVC due to obstructed, hyperinflated lungs limiting air-flow. This can be clarified if necessary by measuring full lung volumes using e.g. a “body box.”)

Question 12

GOLD Stages of COPD

Answer 12

FEV1 >=80% predicted = GOLD Stage I
FEV1 between 50-80% predicted = Stage II
FEV1 between 30-50% predicted = Stage III
FEV1

Question 13

COPD Tx by stage

Answer 13

ALL STAGES: PRN B2-agonist (albuterol) + flu shot

Stage II (Moderate): ADD one or more long-acting bronchodilator QD. Either a LABA (ie salmeterol) OR a long-acting anticholinergic (ie tiotropium) + pulm rehab exercise pgm.

Stage III (Severe): ADD inhaled corticosteroids QD in pts w/ h/o freq exacerbations.

Stage IV (Very severe): ADD long-term O2 if levels are low and consider surgical interventions (lung volume reduction surgery LVRS, lung transplant).