**5. Pathophysiological changes caused by postoperative pain in the organism**

Acute postoperative pain that is poorly treated is associated with both physiological and psychological functions in the body [2, 9–11], which are as follows:


There are negative effects on the muscular system, on the coagulation system, on the wound healing, and on the immune system. Finally, poorly controlled pain after surgery may impair sleep and have negative psychological effects, such as demoralization and anxiety.
