NUR 406 Oxygenation
- 3.5 - 8.5 liters
Answer lung total volume
- pleural space
Answer intrapleural pressure < intrapulmonary pressure inside the lungs
< atmospheric pressure
- diaphragm
Answer innervated by the medulla and the phrenic nerve. Level of C3- C5. Pons controls the rate, depth and rhythm of respiration.
- alveolar cells
Answer type I provide structure to alveolar walls and allows for gas exchange. Type II provides surfactant.
- physiologic shunt
Answer venous blood from the bronchial circulation and from the right coronary circulation enter the left atrium with the oxygenated blood which decreases the oxygenation saturation to 96-99%.
- hypoxic vasoconstriction
Answer compensatory response, probably, that occurs when PaO2 is < 60 mm Hg.The PULMONARY vessels constrict especially the pulmonary capillaries. This decreases blood flow that perfuse under ventilated alveoli. The reason is thought to be that this decreases the amount of unoxygenated blood that returns to the LA. Can cause pulmonary hypertension. 1 / 2
- oxygen dissociation curve
Answer plotting the relationship between dissolved oxygen and hemoglobin. In a healthy person, the PaO2 can decrease significantly (such as down to 60) but this drop only causes a small drop in oxygen saturation to about 89%. Be careful because sometimes O2 sats are a little misleading.
- oxygen curve shift to right
Answer hemoglobin has less affinity for oxygen.This means that saturation level is low but the hemoglobin releases the oxygen easily.
Causes of this shift
Answer
Acidosis Increased PCO2 Increased temp Hyperthyroidism Some anemias Chronic hypoxemia such as high altitude and congenital heart disease Increased 2,3-BPG
- oxygen curve shift to left
Answer higher oxygen saturation and increased affinity of hemoglobin for oxygen. Hemoglobin does not give up its oxygen well.
Causes of this shift Alkalosis Low PCO2 Decreased temp Hypothyroidism Blood that has been banked unless it has been preserved with citrate phosphate dextrose which can preserve 2,3 BPG for several weeks
Carboxyhemoglobin Decreased 2,3-BPG
- Methemoglobin
Answer iron molecules within the hemoglobin oxidize from the ferris state to the ferric state. This does not carry oxygen.
- Carboxyhemoglobin
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