Anesthesiology Pearls

Question 1

What is MAP in terms of hemodynamics?

What is the equation?

Answer 1

MAP = (CO × SVR) + CVP

Based upon the relationship between flow, pressure and resistance:

MAP = Diastolic Pressure + 1/3 (Pulse Pressure)
MAP = 2/3 (Diastolic Pressure) + 1/3 (Systolic Pressure)

Question 2

What shifts the oxygen dissociation curve to the right?

Answer 2

Acid
2,3 BPG
Increased PCO2
Temperature

Question 3

What is Alveolar Dead Space?

Answer 3

Alveoli dead space is sum of the volumes of those alveoli which have little or no blood flowing through their adjacent pulmonary capillaries

i.e., alveoli that are ventilated but not perfused, and where, as a result, no gas exchange can occur.

Alveolar dead space is negligible in healthy individuals, but can increase dramatically in some lung diseases due to ventilation-perfusion mismatch.

Question 4

What is anatomical dead space?

Answer 4

Anatomical dead space is that portion of the airways (such as the mouth and trachea to the bronchioles) which conducts gas to the alveoli.

No gas exchange is possible in these spaces. In healthy lungs where the alveolar dead space is small, Fowler’s method accurately measures the anatomic dead space by a nitrogen washout technique.