Eggena 12-1 Flashcards
Why was she retaining carbon dioxde during manual ventilation?
she was too exhausted to lower intrapleural pressures sufficienty to move air through constricted airways into the alveoli.
Why not give sodium bicarbonate for a respiratory acidosis?
administration of bicarbonate would have generated more CO2 as bicarbonate ions interact with lactic acids that had formed during anaerobic metabolism when blood flow to tissues was inadequate.
Because cell membranes are much more permeable to carbon dioxide than they are to bicarbonate or hydrogen ions, more carbon dioxide would not enter cells without bicarbonate, causing pH to fall to even lower levels.
what was the patient’s alveolar-arterial oxygen gradient during manual ventilation?
42 mm Hg
the diffusion of oxygen across her alveoli was nearly normal, despite her consticted airways.
to diffuse from alveoli to blood
oxygen must first reach the alveoli (bronchioles must not b eplugged or lungs collapsed in that area). The alveolar capillary membrane must be of normal thickness.
When these conditions are met, oxygen will equilibrate across the alveolar capillary membrane so that the oxygen tension in alveoli will be only slightly greater than the oxygen tension in arterial blood.
atelectasis
bronchiole collapse
was supplemental oxygen really needed?
The alveolar oxygen tension would have been 0 mm Hg. She would have died because there would have been no oxygen in blood to sustain life.
why bother inserting an endotracheal tube?
face masks do not have an air tight seal. Air leaked out of the mast due to high pressures needed to force air into her lungs with the ambu-bag.
What was the patient’s alveolar-arterial oxygen gradient after intubation?
It increased dramatically
What caused the increase in her alveolar arterial oxygen content?
the increase in gradient indicated that oxygen was not reaching all alveoli or that it was not diffusing across the alveolar capillary membrane.
The most likely cause was that the endotracheal tube had been advanced to far down past the carina.
Why change the ventilator settings
the FiO2 was reduced, resulting in a low PaO2. Using oxygen too long causes
interference with ciliary function
infterference with pulmonary surfactant formation and secretion by type II alveolar cells.
when nitrogen is replaced by oxygen, there is little gas left in the alveoli to keep them expanded, causing predisposition to atelectasis.
alveolar ventilation can be reduced by
reducing tidal volume
decreasing respiratory rate.
why was she given albuterol, iporatropium, methyprednisone and antibiotics?
albuterol is a beta-2-adrenergic agnoist. It causes bronchodilation and prevents the release of histamine.
ipratropium bocks bronchoconstrictor effects
methylprednisone induces the synthesis of proteins and inhibit histamine and bronchoconstrictors from mast cells.
antibiotics kill bacteria that precipitate an attack in a person with asthma.
Why die she have subcutaneous emphysema?
subcutaneous emphysema is caused by gas bubbles under the skin, which leaked froma hole in the right lung.
how will the subcutaneous emphysema resolve?
a high PO2 gradient causes oxygen molecules to be absorbed from the bubbles into blood.
Why did her blood pressure and pH fall when her face got puffy?
air cannot leave the pleural space through the opening in the lung on expiration. This leads to a rise in intrathoracic pressure.
When cells are deprived of oxygen, they switch from aerobic to anaerobic metabolism and release lactate, causing metabolic acidosis.
