IJCS | Volume 33, Nº1, January / February 2019

31 Table 4 - Assessment of pain medications in the postoperative of patients undergoing minimally invasive cardiac surgery and median sternotomy MS group (n = 17) p-value* MI group (n = 17) p-value* 3 rd PO day 7 th PO day 3 rd PO day 7 th PO day Pain drugs (n/%) 17.0/100.0 15.0/88.3 0.600 16.0/94.1 6.0/35.3† 0.010* Daily prescriptions 1.1 ± 0.3 1.0 ± 0.8 0.600 0.9 ± 0.2 0.3 ± 0.4 0.010* Daily frequency 4.4 ± 1.8 3.0 ± 1.6 0.040* 3.1 ± 1.2 0.8 ± 1.4† 0.001* MS: median sternotomy; MI: minithoracotomy; n: number of patients; %: frequency; PO: postoperative; *: p < 0.05 within group by paired Student’s t-test for continuous variables and z test for categorical variables; † p<0.05 between groups by unpaired Student’s t-test for continuous variables and z test for categorical variables; 95% confidence level. Silva et al. Minimally invasive surgery–pain investigation Int J Cardiovasc Sci. 2020;33(1):24-33 Original Article In addition, the number and sites of the incisions differed between the groups. The MS group had two thoracic incisions (main and chest tube incisions). The MI group had two incisions (thoracic and inguinal) and at least three right thoracic punctures. For the main incision, we used a wound protector for soft tissue 34 to diminish intercostal retraction that could lead to nerve stimulation 11,35 during the procedure (e.g. valve replacement), which could be a cause of pain. We observed moderate to intense pain after both surgical approaches (MS and intercostal). According to the literature, at least 60% of the patients who underwent MS andMI procedures report moderate to severe pain in the early PO days. 1 As expected, the main sites of pain were directly related to the surgical incision, i.e., the sternal wound for MS patients and the inframammary area for patients who underwent MI procedure, although the MS group also reported extra-wound pain sites (posterior thoracic area). Although MI procedure involves a higher number of incision/punctures, these patients did not report more pain sites as compared with those undergoing MS procedure. Regarding PI, we observed that the most remarkable differences between the groups occurred on the seventh PO day. There were no significant differences in PI between the third and the seventh PO days in the MS group. This data agrees with the study by Mueller et al., 27 that indicated a slow reduction of thoracic pain following a sternal based procedure. On the other hand, there was a statistically significant reduction in PI from the third to the seventh PO days in the MI group. The presence of moderate to severe pain on the third PO day for both groups was in accordance with previous studies. 1,11,23,35,36 Landrenaeu et al., 37 and Nagahiro et al., 38 compared conventional posterolateral thoracotomy with MI (video-assisted) thoracotomy procedures and verified that the MI approach promoted less postoperative PI. The advantages regarding PI and length of hospital stay for the MI procedures are well established 1 and were corroborated in our study. In patients subjected to MI procedure, there was lower PO pain and need for pain medication, and shorter ICU and hospital stay (19 hours shorter and two and a half days shorter, respectively). It is worthmentioning that although the group differed in the presence of comorbidities, no PO complications related to these conditions were found in neither of the groups, such as hypertensive crisis or pulmonary complications. This work resulted in important findings regarding PO pain, a symptom often overlooked by healthcare professionals dealing with cardiac surgery. Wildgaard et al., 11 noted that the strategies for PO pain control after thoracic procedures has evolved in the last years. However, inadequate pain management still affects the quality of life and postoperative outcomes of cardiac surgery patients, 8,9 whereas adequate pain control results in better rehabilitation after a cardiovascular surgical procedure. Thus, painmanagement is a challenging task, as it demands attention by health professionals inmaking correct decisions towards medications and PI ratings, considering patients’ pain tolerance and differences between protocols. Despite all advances in the diagnosis andmanagement of PO pain, accurate evaluation of this symptom is still very difficult, since the perception of pain and the response to pain medications vary widely between individuals. Also, the experience of the surgical team on MI procedures reduces possible complications of this type of surgery. A multicenter study involving larger