Final answer:
Preoxygenation replaces the lungs' nitrogen content with oxygen, increasing safety during anesthesia and delaying hypoxemia. Accurate preoxygenation should eliminate most of the nitrogen (~75%) and replacing it with oxygen according to the total alveolar pressure composition.
Step-by-step explanation:
Preoxygenation and Nitrogen Elimination
Effective preoxygenation in the medical context refers to the preparation of a patient for anesthesia, particularly before intubation, by providing a high concentration of oxygen. This process serves to replace the nitrogen content in the lungs' functional residual capacity with oxygen, thus increasing the oxygen reserves in the patient's body and delaying the onset of hypoxemia during apnea. The air human beings breathe contains approximately 78% nitrogen and 21% oxygen. During preoxygenation, the aim is to greatly reduce the nitrogen percentage, maximizing oxygen content to enhance patient safety.
According to Table 22.3, the total alveolar pressure is comprised of nitrogen (74.9%), oxygen (13.7%), water (H2O) (6.2%), and carbon dioxide (CO2) (5.2%) which sums up to 100% of the total composition. When preoxygenation is properly administered, most of the nitrogen present is eliminated and replaced with oxygen. The options provided (79, 2, 4, 6, 8) are likely referring to the amount of nitrogen eliminated. Since nitrogen composes approximately 75% of total alveolar pressure, proper preoxygenation should eliminate most of this, which would be around option 1) 74 or 75, effectively replacing it with oxygen to increase the patient's oxygen content and reserves.