The effects of erector spinae plane block on systems in the postoperative period in open heart surgery patients with sternotomy

Objective: Postoperative pain in cardiac surgery may have adverse effects on all organ systems, especially the respiratory system. Stress response and neuroendocrine changes secondary to surgery cause various complications. Intravenous opioid analgesia is the oldest known and widely used method of pain management. Recently, it has been suggested that the erector spinae plane (ESP) block may provide effective analgesia, thereby reducing multisystemic complications secondary to surgical stress and neuroendocrine response. In this study, we planned to compare the effects of bilateral erector spinae plane block on postoperative laboratory parameters with intravenous opioid analgesia. Materials and Methods: This study was conducted as a prospective, single-center, randomized controlled. A total of 65 patients in the ASA II-IV risk class, aged 18-85 years, with a body mass index <35, were included. Patients were randomly divided into two groups: ESP block (Group E, n=33) and intravenous fentanyl infusion (Group F, n=32). All patients admitted to the operating room underwent hemodynamic monitoring as part of the anesthesia routine. Before induction of general anesthesia, patients in Group E underwent bilateral ESP block using a total of 40 ml of 0.375% bupivacaine 0.375%, 20 ml on each side, using an in-plane technique at the level of T4 vertebrae in the sitting position. Patients in Group F received intraoperative fentanyl infusion of 0.5 µg/kg/hour after induction of anesthesia. All patients underwent standard general anesthesia induction. In the post-extubation period, additional analgesic needs, pain scores (numeric rating scale (NRS)) and tidal volume (TV) values by volumetric spirometry (at 0,2,6,12,24,36 and 48 hours), sociodemographic data, preoperative and postoperative laboratory variables, perioperative fluid and blood/blood product transfusion requirements, postoperative cardiorespiratory and renal complications, surgery-related times, and hospitalization times were recorded. Results: When demographic data were compared, similar results were obtained between the groups. Comorbidity distributions were similar between the groups. When perioperative surgery-related times were evaluated, the first postoperative mobilization time and hospital stay were shorter in Group E. When the pain scores assessed in the first 48 hours after extubation were compared, the NRS was significantly lower in the ESPB group at 0, 2, 6 and 12 hours. Additional analgesia consumption was significantly lower in the ESPB group, and the need for additional analgesia occurred later in the ESPB group. Tidal volume values evaluated in the first 48 hours after extubation were higher in the ESPB group at all times after extubation. When postoperative respiratory complications were evaluated, the frequency of fever, tachypnea and increase in mask oxygen requirement were higher in the IV fentanyl group. No significant difference was observed when blood gas parameters were compared between the groups. Postoperative cardiac complications, perioperative fluid resuscitation and diuresis, and the need for postoperative renal support were not significantly different between the groups. When postoperative laboratory parameters were compared, hemoglobin and hematocrit values were significantly higher in the ESPB group, while similar results were found for all other parameters. In addition, similar results were observed when preoperative and Δchange laboratory values were compared between the groups. Conclusion: ESP block has the advantages of providing non-opioid analgesia without opioid side effects compared to intravenous analgesia, higher TV values and lower frequency of respiratory complications, early mobilization and shorter hospital stay thanks to its superficial facial plane block and less invasive method. For these reasons, we believe that ESP block will provide better clinical outcomes in open heart surgeries performed via sternotomy. Keywords: Sternotomy, Erector Spinae Plan Block, Intravenous Opioid Analgesia, Postoperative Systemic Effects, Tidal Volume, Postoperative Analgesia