It was recently reported that ipratropium bromide and tiotropium bromide posed a significantly increased risk of heart disease and stroke. The following was the conclusion of that recent report in the Journal of the American Medical Association from September 24, 2008:
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Inhaled anticholinergic (ipratropium) use for more than 30 days significantly increases the risk of cardiovascular death, MI, or stroke in patients with COPD by approximately 58%. This increase in the risk of cardiovascular death, MI, or stroke is particularly manifest in the long-term trials.
The precise biological mechanisms by which inhaled anticholinergics increase the risk of cardiovascular death, MI, or stroke among patients with COPD are uncertain. That means that, they are unknown!. These risks may or may not be real.
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Some individuals may experience a fall in oxygen saturation following the administration of an inhaled bronchodilator. If severe enough, this could result in that person losing consciousness. It is possible then that your uncle may be having an adverse response to the albuterol and/or ipratropium bromide.
You should discuss this with his doctor and arrange for your uncle to administer his inhaled medicine(s) in a safe environment, such as the doctor's office or emergency room (ER) where his blood oxygen levels and heart rhythm can be monitored.
As to the question of which came first, passing out or low oxygen level? The answer is either 1 but more likely the passing-out was due to a low oxygen level. However, if his breathing either slowed or stopped when he lost consciousness, a low oxygen level would follow the fainting.