Geriatrics Flashcards
What is 1 MET?
3.5mLO2/kg/min
Or, about 250mL/min for 70kg patient
Minute ventilation in the eldely
Increases to compensated for the increase in dead space 2/2 small airway closure
Lung elasticity
Decreases, resulting in slower of small airways and the lung to be overfilled with gas.
Increased dead space Decrease alveolar surface area Increased A-a gradient VQ mismatch Decreased PaO2 Altered lung volumes
Chest wall compliance
Decreased
This is because of:
- Flatter diaphagm
- Increased AP diameter
- Decreased intercostal mass
- Joint falcification
- Loss of intervertebral disc height
Results in increased WOB
Consequences of loss of elastic recoil
Airways don’t spring back. They inflate, but don’t spring bag. It’s like inflating a plastic shopping bag. On exhalation, and pressure in the chest becomes positive, these flimsy airways collapse, and the air in the shopping bag is trapped.
What does it mean when closing capacity surpasses FRC?
Closing capacity is the volume of air that must be in the lungs to prevent airway collapse.
If it surpasses FRC, it means that airways will collapse during normal tidal breathing.
This happens at age 45 in the supine position and will happen at age 65 in the standing position.
This collapse results in increased dead space, VQ mismatch, and a reduction in PaO2.
Vital capacity in elderly
Reduced.
The chest wall is less compliant and muscles are weaker and diaphragm is weaker. Can’t take in a huge breath.
What is special about alpha 1 acid glycoprotein in the elderly?
It binds to basic drugs, and it’s production is actually INCREASED in the elderly
Acid binds with base!
Albumin binds what types of drugs?
Acidic drugs
Albumin is decreased in the elderly
Pseudocholinesterase in the elderly
Decreased
Liver function in the elderly
Hepatocytes work normally!
What’s reduced is hepatic BF and hepatic mass. Periop hepatic function is decreased as well.
Phase I and II reactions in the elderly
Phase I (oxidation, reduction, and hydrolysis) are reduced.
Phase II (conjugation and acetylation) are unchanged