Patho Exam 2: Respiratory Distress & ARDS (Lecture 2) Flashcards
(29 cards)
What is the primary function of the lungs?
oxygenate blood and remove CO2
What is Acute Respiratory Failure?
Lung cannot perform their primary role in gas exchange.
End-result in longstanding respiratory disease or complication of another disorder.
How do you define respiratory failure in values of paO2 and paCO2?
paO2 <50-60 mmHg
paCO2 can be high or low (= 50 mmHg)
Define hypoxemic (normocapnic) in terms of paO2 and paCO2
Hint: “cap” = CO2
Low paO2
Normal paCO2
Define hypercapnic (ventilatory respiratory failure) in terms of paO2 and paCO2
Hint: “cap” = CO2
Low paO2 High paCO2 (pt is retaining to CO2 in their body)
Intrinsic & Obstructive respiratory failure is related to…
Hint: COPD
Hypercapnic
- issue with taking CO2 out
- COPD builds up in blood
Intrinsic & Restrictive respiratory failure is related to…
Hypoxemic
-restricts proper O2 intake
Extrinsic respiratory failure is…
Hint: Trauma, narcotic
Hypercapnic
What is the general rule for PCO2 and PO2
Hint: Inverse relationship
PCO2 increase; PO2 decrease
PCO2 decrease; PO2 increase
Increase affinity to Hgb means…
Easy to bind but Harder to take O2 off of Hgb; Left shift
Decrease affinity to Hgb means…
Harder to bind but Easier to take O2 off of Hgb; Right shift
i.e: Exercising
If there is an increase in CO2, what affects does it have on pH and affinity?
Increase CO2 = acidosis (more acidic) = decrease in O2-Hgb affinity
Increase in temperature; febrile
A decrease in CO2 would affect the pH and affinity in what way…
Decrease CO2 = alkalosis (more basic) = increase in O2-Hgb affinity
Decrease in temperature
What are the s/s of hypoxemia? What are the PO2 levels during hypoxemia?
Hypoxemia begins when PO2 drops is 40-50mmg.
- Pts will express confusion, motor impairment, slurring of speech.
- Initially, tachycardic and hypertensive but will become bradycardic and hypotensive later.
- Pulmonary blood vessels constrict (helps increase BP in surrounding tissues)
What are the s/s of hypercapnia?
Always associated w/ hypoxemia
- CNS depression (CO2 narcosis)
- Cerebral vasodilation (give all O2 to brain)
- Pulmonary vasoconstriction
- Respiratory acidosis (due to high levels of CO2)
Why wouldn’t sx’s concerning increase in PCO2 be presented in a pt w/ h/o COPD.
Body adapts to chronic high levels of PCO2. Pts w/ h/o COPD, having higher chronic levels of PCO2, may not present w/ sx’s unless there is a markedly elevated level of PCO2 if susceptible.
The hypercapnia range of PCO2 is > 50 mmHg, distinguish the ranges of further hypercapnia and their associated sx’s.
PCO2 60-75mmHg = air hunger, rapid breathing (to breath off CO2)
PCO2 80-100mmHg= disorientation, lethary, semi-comatose
PCO2 >100mmHg = comatose, anesthesia, death.
The ranges in ABG to diagnose respiratory failure are…
ABG ranges:
PO2 = 50-60 mmHg or less
PCO2 = 50 mmHg or more
Respiratory acidosis is…
Hypercapnia (Increase in CO2)
Alveolar HYPOventilation
Respiratory alkalosis is…
Hypocapnia (Decrease in CO2/acidity)
Alveolar HYPERventilation
What are the systems responsible to maintain acid-base balance
- Hematologic (RBCs)
- Lungs (blowing off CO2 to decrease acidity
- Kidneys (excretion and retention)
Define and describe ARDS?
ARDS: Acute/Adult Respiratory Distress Syndrome
“Acute lung injury” with high mortality (50-60% mortality)
- alveoli are diffusely injured, decrease massive amount of gas exchange
Why is ARDS so severe?
Due to the untreatable infiltrates and severe hypoxemia.
Damage to diffuse alveoli w/ no response to treatment = no gas exchange.
Pathophysiology behind ARDS
AC-membrane is severely damaged (direct or non-direct)
This causes massive inflammatory = capillaries expand and leak = increase capillary permeability
Cause WBC response; neutrophils, macrophages and platelets
