Pain is a very subjective matter - what may be very painful for one person, may not be so painful for another. For this reason, many healthcare professionals use a number pain scale to rate how the patients are feeling. This pain scale ranges from zero to 10, with zero being no pain and 10 being the severest pain possible.
This approach, however, isn't always possible with non-verbal patients and needs adapting. One way is to have a visual scale of zero to 10, perhaps a large graph, that the patient can point to in order to tell the nurse of the pain level. Or, the nurse could do it on a scale of zero to five, using fingers to demonstrate pain levels.
Such approaches don't address the needs of patients who may not be able to communicate at all, though. In this case, the healthcare professionals need to be aware of body language. Assessments need to be made regularly and consistently. One recent article discussed a new rating scale called the Elderly Pain Caring Assessment, which has eight assessments, including facial expression and body posture, to be assessed and rated by the caregivers.