When I’m teaching airway management to my Perioperative/OR nurses, I often recount the story of management of a young child’s postoperative respiratory depression. In addition to illustrating the importance of evaluating ventilation in addition to oxygenation, this case shows how good communication makes management of a critical event more effective. Read More …
There are 2 types of mismatch: dead space and shunt. Alveolar gas exchange depends not only on ventilation of the alveoli but also on circulation of blood through the alveolar capillaries. This makes sense. You need both oxygen in the alveoli, and adequate blood flow past alveoli to pick up oxygen, other wise oxygen cannot be delivered.
When the proper balance is lost between ventilated alveoli and good blood flow through the lungs, ventilation/perfusion mismatch is said to exist. The ventilation/perfusion ratio is often abbreviated V/Q. V/Q mismatch is common and often effects our patient’s ventilation and oxygenation. Read More …
I often find that my students sometimes confuse oxygenation and ventilation as the same process. In reality they are really very different. Ventilation exchanges air between the lungs and the atmosphere so that oxygen can be absorbed and carbon dioxide can be eliminated. Oxygenation is simply the addition of oxygen to the body.Why do we need to understand this? Let’s look at some common examples. Along the way we will painlessly use the Alveolar Gas Equation to explain two common scenarios:
how hypoventilation causes hypoxia,
why abruptly taking all supplemental oxygen away from a carbon dioxide retainer will hurt them. Read More …