Pulmonary Lab Med 1 Flashcards
once you get a PPO2 of what, will you % saturation of 90
60
What things cause a left shift of the curve?
decrease temp
decreased 2-3 DPG
decreased (H+)
CO
the higher the elevation…..
the less barometric pressure there is to push the oxygen on the hemoglobin
how long does it take for a molecule of O2 to get across the interstitial membrane
3/4 of a second
what can you do to test if the time for molecule to get across the interstitial membrane is longer?
exercise them
does alveolar hypoventilation occur in dz processes of the lung?
No, when something else is going on that causes elevated pCO2 and decreased PO2
what are some things that cause alveolar hypoventilation?
Drugs
CNS injury
neuromuscular weakness (myastenia gravis)
obesity
what should be removed before using a pulse ox?
remove nail polish
make sure hands arent cold
example of a shunt in pulmonary
lobar pneumonia (densely occupied part)
does an increase in oxygen help solve a shunt problem?
No because the blood is shunted anatomically
4 diseases that cause V/Q mismatch
COPD
Asthma
Pneumonia
Pulmonary emobilsm
what is the most common cause of hypoxia and can be corrected w/ oxygen?
V/Q mismatch
normal PaCO2
35-45
normal PaO2
70-80
Normal O2Sat
90-96%
Normal HCO3?
24-28
what regulates the PaCO2 rate?
alveoli
what regulates the HCO3 level?
Kidneys
The hydrogen ion concentration [H+] in extracellular fluid is determined by the
balance between the partial pressure of carbon dioxide (PCO2) and the concentration of bicarbonate [HCO3-] in the fluid.
how long does it take the kidneys to make a compensatory response?
72 hours
PaCO2 elevated – causes: Drug OD, COPD exacerbation with respiratory failure
Respiratory acidemia
PaCO2 low causes: sepsis, altitude, aspirin OD
Respiratory alkalemia
HCO3 low – causes lactic acidosis, ketoacidosis, renal failure, severe diarrhea
Metabolic acidemia
HCO3 high – diuretics, vomiting, ng suction, NA HCO3 ingestion
metabolic alkalemia
If pH is normal and pCO2 and HCO3 are abnormal then __________ EXISTS
compensation
pH is abnormal, and both pCO2 and HCO3 are abnormal what is hapenning?
two separate abnormal processes can be occurring without compensation
pH normal + increased pCO2 + increased HCO3
compensated respiratory acidosis
pH normal + decreased HCO3 + decreased pCO2
compensated metabolic acidosis
what’s another way to get a CO2 level besides ABGs?
BMP
pH>7.50 + pCO2<30 + normal HCO3
uncompensated respiratory alkalosis
pH>7.50 + HCO3>30 + normal pCO2
uncompensated metabolic alkalosis
respiratory causes of acidosis
hypoventilation
impaired gas exchange (V/P mismatch)
metabolic causes of acidosis
Ketoacidosis (i..e diabetes) Renal Tubular Acidosis (i.e. renal failure) Lactic Acidosis (i.e. Decreased perfusion or severe hypoxemia)
what is the anion gap?
Na+ – (Cl- + HCO3-)
if the anion gap is > 12 what does that indicate?
anion gap acidosis
what does MULEPAK stand for?
causes of an anion gap
Methanol, Uremia, Lactic Acidosis, Ethylene Glycol, Paraldehyde, ASA, Ketoacidosis
respiratory causes of alkalsosi
Hyperventilation due to hyoxemia, metabolic acidosis, neurologic
meatbolic causes of alkalosis
hypokalemia
gastric suction or vomiting
hypocholemia
with hyperchloremia is there an elevated anion gap?
No
some indications for pulmonary function tests
SOB, exertional dyspnea, chronic cough
what can spirometry determine
FEV1
FVC (forced vital capacity)
FEV1/ FVC
forced expiratory flow (FEF) in small airways
with obstructive lung dz what will happen to the FEV1 and FVC?
Decreased
with obstructie lung disease what is FEV1/ FVC below?
<70%
what is used to follow severity in COPD?
FEV1
Name a differential for obstructive lung dzs
Asthma COPD bronchiectasis bronciolitis upper airway obstruction
is the relationsihp between FEV1 and FVC decreased in restrictive patterns?
No, usually normal or increased
name some restrictive lung dzs
pleural (cancer)
parenchymal
chest wall (broken ribs)
neuromuscular (guillan-burre, MG)
what does a improved FEV1 after a bronchodilator indicate?
A reversible airflow obstruction
what is considered improvement on FEV1 after a bronchodilator?
12-15% improvement
Spirogram that Measures forced inspiratory and expiratory flow rate. Augments spirometry results.
Flow volume loop
what are indications for a flow volume loop?
Evaluation of upper airway (stridor, unexplained dyspnea)
how do you measure lung volumes?
helium
- nitrogen washout - body plethsmography
when are lung volumes indicated
Diagnose restrictive component
Differentiate chronic bronchitis from emphysema
Measures ability of lungs to transport inhaled gas from alveoli to pulmonary capillaries
diffusing capacity
what does diffusing capacity depend on?
alveolar—capillary membrane
hemoglobin concentration
cardiac output
what can cause a decreased DLCO
obstructive lung dz
parenchymal dz
pulmonary vascular dz
anemia
what can cause increased DLCO
asthma (or normal)
pulmonary hemorrhage
polycythemia
left to right shunt
Indications for DLCO
Differentiate asthma from emphysema
Evaluation and severity of restrictive lung disease
Early stages of pulmonary hypertension
(it is expensive)
Useful for diagnosis of asthma in the setting of normal pulmonary function tests
Bronchoprovocation
common agents for bronchoprovocation
Methacholine, Histamine, others
when is a bronchoprovocation considered diagnostic
≥20% decrease in FEV1
with emphysema what happens with the TLC?
TLC is increased
what happens with the DLCO with empysema?
decreased
A 36yo WF, non-smoker, presents to your office for follow-up of ‘recurrent bronchitis.’ You suspect asthma and decide to order spirometry. Which of the following would you include in your prescription for testing?
if no obstruction present, perform methacholine challenge
Exhaled Nitric Oxide is elevated in patients with ______________________________
eosinophilic inflammation
what is an x-ray with smaller thorax helps to see pneumothorax better
Expiratory film
what ribs do you see on an x-ray?
posterior
what can shift the hilum toward the problem?
atelectasis
fibrosis
post pneumoectomy
what can a shift of the hilum away indicate?
pleural effusion air trapping tension pneumo pneumo tumor
When the lung is consolidated and the bronchi contain air, the dense lung delineates the air in the bronchi
air bronchogram
Fluffy Poorly defined Often contain air bronchograms ARDS, Pulmonary Edema, bacterial pneumonia Diffuse, focal
Alveolar infiltrates
streaky infiltrates
linear, nodular diffuse
associated w/ fibrosis, heart failure
interstitial infiltrates
any pulmonary lesion represented in a radiograph by a sharply defined, discrete, nearly circular opacity 2-30 mm in diameter
Nodule
what is larger than 3 cm seen on x-ray?
mass
Scarring of lung due to injury Chronic aspiration Inhalation injury Acute Respiratory Distress Syndrome Infection Occupational exposures Collagen-Vascular related
pulmonary fibrosis
when do you use CT with contrast
concerned about something vascular
when do you get a sputum sample
underlying lung dz
best if first morning sample, shouldn’t have >25 squamous cells (that indicates saliva)
when would you use the methacholine challenge?
if PFTs are normal are you suspect asthma
when is a methacholine challenge diagnostic?
> 20% decrease FEV1
If you see a “sail collapsed” on a FV loop what should you suspect?
Obstructive pattern
What does the FV loop look like on a restrictive pattern?
Decreased
If you have a restrictive lung dz and then you get a DLCO and it is decreased what do you suspect?
parenchymal disease
Is DCLO normal for chronic bronchitis or emphysema?
chronic bronchitis
how do you evaluate pulmonary HTN?
echocardiogram + doppler
best test is cardiac catheterization with direct measurement of pulmonary arterial pressure
Is TLC normal in emphysema or chronic bronchitis?
Chronic bronchitis
lines that indicate fluid accumulation
Kerley B lines
pH < 7.30 + pCO2 >50 + normal HCO3
uncompensated respiratory acidosis
pH < 7.30 + HCO3<18 + normal pCO2
uncompensated metabolic acidosis
