Today I came across a Reddit AMA with David Belk MD: https://www.reddit.com/r/IAmA/comments/4lgnif/i_am_david_belk_im_a_doctor_who_has_spent_the/
His site's intro video:
He summarizes the history of health care expenses and insurance and explains his conclusion of the causes of prices getting so insanely high on this page: http://truecostofhealthcare.net/conclusion/
The bottom line seems to be that there are multiple failures in efficiency due to intentional opaque pricing by the entrenched healthcare and insurance establishment, and that transparency and the fair pricing that would come along with it would do much to solve the issue.
I personally haven't faced many acute medical issues but I recall looking at the item on a bill for a small filter for someone else's CPAP machine that was rented from a local medical supply company. The filter was basically a 1x2 inch square piece of foam and cost over $40.
$40 for this: 
I got that image from here, which sells a 2-pack for $2.66.
Things like this are ridiculous and need to change. Health is important and health care is certainly valuable but the way prices have evolved in the United States is unacceptable.