I am certain that I read an article in DAN a few years ago about similar
safety stops and micro-bubble formation.  DAN was doing Dopplar research
and had discovered that the multilevel stops greatly reduced the formation
of micro-bubbles in the blood.  My recollection from the article was a
recommendation of stops at 20 FEET for two minutes and one minute at 10
feet.  My metric conversions are very bad but it sounds like your stops
were much deeper.  The DAN study showed a dramatic difference from those
divers who had done the traditional 15 feet (5m) for 3 minutes. After
reading the article I have tried to change my stops as suggested.

In any event, I am sure Doc Lance will have a better recollection.

Dive Safe,

Don.