Recently, during my Obstetrics rotation, I saw a woman with very high blood pressure. She was 36 weeks pregnant. I wondered whether her blood pressure was elevated due to the cuff being too small. I asked around, and a few people vaguely remembered that there was once a large cuff but they weren't sure where it was. I eventually found a thigh-sized cuff which gave a much lower reading. It may have been inaccurate too, because the thigh cuffs tend to be too wide for fat arms (unless the fat arms happen to belong to a very tall person).
Nobody else really seemed to think the lack of an appropriate BP cuff was a big deal. I think it's not just a big deal, but totally unacceptable. There needs to be a large cuff available in every ward in every hospital that treats a general adult population. Too-small cuffs directly affect patient care.
Here's a pie-in-the-sky dream: I wish we (the fat acceptance & HAES communities) could raise money to send one-piece large-cuff sphygmomanometers (like the Welch-Allyn DS44-12) to hospitals and clinics, along with a letter discussing the importance of providing appropriate care to large patients!
Edited to add: Thanks to living400lbs for providing the link to Well-Rounded Mama's excellent series about the need for large blood pressure cuffs.