Fig. 2From: Effects of patient-controlled analgesia with hydromorphone or sufentanil on postoperative pulmonary complications in patients undergoing thoracic surgery: a quasi-experimental studyPain NRS (numerical rating scale) distribution in both the groups at 0 h(A), 6 h(B), 12 h(C), 24(D)and 48 h(E) after surgery. (* represented significant difference between group A and group B)Back to article page