Comparison of the effect of preemptive and postoperative erector spina plan block on intraoperative opioid consumption and postoperative analgesia guided by nociception level index (NoL) in patients undergoing elective thoracotomy surgery

Aim: One of the most painful surgeries is a thoracotomy in which successful management of analgesia in the postoperative period has an important role in reducing secondary pulmonary complications, morbidity and length of hospital stay. In recent years, Erector Spina Plan Block (ESPB) has been frequently used in the analgesia management of thoracotomy procedures. In this study, we aimed to determine the effect of preemptive or postoperative application of ESPB on the amount of intraoperative opioid consumption by Nociception Level Index (NoL) monitoring, to compare its effect on analgesic requirement and pain scores in the postoperative period, and to compare the side effects associated with opioid consumption. Materials and Method: Fifty-two patients aged between 18-65 years, with a body mass index (BMI) below 30 and ASA I-III were included in the study which is prospective, randomised and controlled. The group that received preemptive ESPB was named as Group I and the group that received ESPB block at the end of surgery was named as Group II. When the NoL value exceeded 25, 25 mcg fentanyl intravenous bolus was administered as a rescue analgesic. Demographic characteristics, surgeries, duration of surgery, intraoperative fentanyl consumption, VAS values at the 1st, 2nd, 6th, 12th and 24th postoperative hours, complaints of nausea, vomiting and pruritus, additional analgesic needs, postoperative fentanyl consumption, chest tube withdrawal day and discharge days were collected. Results: A total of 52 patients, 25 (48.1%) females and 27 (51.9%) males, were enrolled in the study. The groups were similar in terms of demographic characteristics. When the need for rescue analgesics based on the NoL value was evaluated, there was a difference between the groups in terms of intraoperative fentanyl consumption (p=0,006). The total amount of fentanyl consumed intraoperatively in the Group I was 143,27±39,723 mcg, whereas the Group II consumed 179,23±49,350 mcg. When Visual Analogue Scale (VAS) scores were compared between the groups in the postoperative period, a statistically significant decrease was observed in the Group I group at the 2nd and 6th hour in the resting state (p=0,007 and p=0,003, respectively). Movement-related VAS scores were significantly lower in the Group I at 1st, 2nd, and 6th hours (p=0,009, p=0,004, and p=0,011, respectively). Cough-related VAS scores were significantly lower in the Group I at 1st, 2nd, and 6th hours (p=0,003, p=0,005, and p=0,006, respectively). The number of analgesic requests based on the patient-controlled analgesia device was higher in the Group II after the surgery at all times (p=0,049, p=0,002, p=0,019, p=0,022 and p=0,022, respectively). Additional analgesic demand was significantly lower in the Group I at the 1st and 2nd hour (p<0.001 and p<0.001, respectively). Conclusions: Intraoperative opioid requirement can be reduced via preemptive ESPB in thoracotomy surgeries. In addition, compared to postoperative ESPB block, preemptive ESPB results in lower postoperative pain scores and a reduced requirement for postoperative opioids and other additional analgesics. Keywords: preemptive analgesia, erector spina plan block, nociception level (NoL) index, thoracotomy, opioid consumption