Apparently google is grouping the patents by families and giving you the number of patent families but sorts them into classifications too, effectively giving not even the number of families.
The first page provided by you gives "about 27" results
It lists 2 patents of classification A61B5/150061 - and I counted, included in the 27 results are only those 2 - but if you click "Search within classification A61B5/150061 (8 results)" (where it already says 8 results, not 2 ...)
You get 3 results - not 8, not 2.
Click on the second patent
and you'll see that it says "also published as (41)"
Together with the fact that there appear almost only US patents in the first 27 results (1 EP), I conclude that google has some kind of sorting by families AND classifications that screws up the number of results. This merely proves that google is not (yet?) as good as commercial/dedicated analysis tools.