Why does a bed sore develop?

Pressure Sore. Pressure or bed sores develop due to a reduced amount of blood flow to the effected body part over a long period of time. To help prevent them it is important to rotate or shift the body to evenly distribute pressure. If an ulcer develops or looks like it may develop it is very important to treat it seriously and have a wound care specialist recommend treatment/prevention options.
Pressure ulcer. Agree with other docs. Watch for red area that doesn't blanch with pressure; usually over bony prominence-first sign, even before skin breakdown.
Exceptions. I am aware of three exceptions to the preventable rule. Patient noncompliance tissue failure - a complex term that basically means that the patient is dying and no matter what you do, they will have skin breakdown. Hemodynamic instability - patients in critical condition for whom turning or position changes cause significant problems with their hemodynamics. Otherwise, they should not occur.
Cause Pressure Sore. Pressure causes a bed sore. One unknown is how long does it take a pressure ulcer to develop. There are many risk factors including diabetes mellitus, low blood pressure, moisture from incontinence or perspiration, fungal infection, use of medical devices, etc. We simply do not know for an individual patient whether rotating them every five minutes or every two hours will prevent pressure injury.