Background: Emergency Laparotomy and Its Challenges Emergency laparotomy is one of the most commonly performed life-saving abdominal procedures worldwide, undertaken in critically ill patients with conditions such as perforated viscus, intestinal obstruction, ischemia, or severe intra-abdominal sepsis. Despite advances in surgical and anesthetic techniques, emergency laparotomy continues to be associated with high morbidity and mortality, ranging between 15–30% in many series【1,2】. These patients frequently present with significant physiological derangements, hemodynamic instability, and multiple comorbidities, making perioperative management especially challenging【3】. Postoperative pain after emergency laparotomy is often severe, arising from both somatic incisional pain and visceral nociception, and if inadequately treated, may contribute to respiratory complications, impaired mobilization, and delayed recovery【1,4】. Effective pain management is central to improving outcomes in this cohort. However, in the emergency setting, analgesic strategies are often complicated by contraindications, limited time, and patient instability. Conventional systemic opioid therapy, while widely used, carries risks of respiratory depression, sedation, ileus, nausea, and vomiting【5】. On the other hand, regional techniques such as thoracic epidural analgesia and paravertebral block, although effective in elective settings, are often unsuitable in emergencies due to hemodynamic compromise, coagulopathy, or sepsis【6,7】. Hence, there is a need for a safer, technically simpler, and more versatile analgesic strategy that can be applied even in critically ill, unstable patients. Pathophysiology of Pain in Emergency Laparotomy The pain following a midline laparotomy incision is complex, involving contributions from both somatic and visceral pathways. Somatic pain arises from the abdominal wall incision, muscle, and fascia, transmitted via thoracolumbar spinal nerves, while visceral pain results from peritoneal and intra-abdominal organ handling【8】. This dual component of nociception makes laparotomy one of the most painful abdominal procedures. If untreated, severe pain triggers neuroendocrine stress responses, sympathetic activation, tachycardia, hypertension, and increased myocardial oxygen consumption, which can be particularly detrimental in elderly or high-risk patients【9】. Moreover, splinting and shallow breathing due to pain predispose to atelectasis, pneumonia, and hypoxemia, while impaired coughing increases the risk of retained secretions【10】. Opioid-based regimens, although effective in reducing pain intensity, fail to completely address these pathophysiological changes and are associated with immunosuppression, ileus, and delayed gastrointestinal recovery【5,11】. Therefore, multimodal analgesia, preferably incorporating regional anesthesia techniques, is recommended for improved outcomes【12】. Limitations of Conventional Analgesic Techniques Epidural analgesia has long been considered the gold standard for midline laparotomy due to its ability to provide excellent segmental analgesia and reduce opioid requirements【13】. However, its use is often precluded in emergencies due to sepsis, hypotension, or anticoagulation. Epidurals also require expertise, carry risks of dural puncture, epidural hematoma, abscess, and sympathectomy-related hypotension, which may be poorly tolerated by critically ill patients【14】. Similarly, paravertebral block provides unilateral segmental analgesia but is technically demanding, associated with pleural puncture risk, and less suited for bilateral incisions【7,15】. Transversus abdominis plane (TAP) blocks and rectus sheath blocks have gained popularity for abdominal wall analgesia, but they are limited to somatic coverage and fail to address visceral pain adequately【16】. Thus, despite the available armamentarium of techniques, an ideal block that is simple, safe, and effective for emergency laparotomy patients has remained elusive. Emergence of the Erector Spinae Plane Block (ESPB) The erector spinae plane block (ESPB), first described in 2016, has emerged as a promising alternative. It involves the deposition of local anesthetic into the fascial plane deep to the erector spinae muscle at the level of the transverse process【17】. This allows spread cranio-caudally over multiple vertebral levels and anteriorly into the paravertebral and epidural spaces, thereby blocking both dorsal and ventral rami and sympathetic fibers【17,18】. The result is coverage of both somatic and visceral pain pathways, making ESPB particularly suitable for abdominal surgery【19】. Ultrasound guidance has further improved the safety and reproducibility of ESPB, with clear visualization of bony landmarks and fascial planes【20】. Unlike epidurals, ESPB does not involve entry into the neuraxial space, thereby reducing risks of neuraxial hematoma or infection, and sympathetic blockade is minimal, making it hemodynamically stable. These advantages are especially relevant in emergency laparotomy where patients are often anticoagulated, septic, or unstable【6,9】. Evidence for ESPB in Abdominal Surgery A growing body of literature supports ESPB in various abdominal surgeries. Randomized controlled trials have demonstrated its efficacy in laparoscopic cholecystectomy, hernia repair, gastrectomy, hepatectomy, and prostatectomy【13–16,18–19】. For example, Abu Elyazed et al. showed significant reductions in pain scores and opioid use after epigastric hernia repair with ESPB compared to controls【14】. Aksu and colleagues demonstrated superior analgesia with ESPB compared to sham injections in laparoscopic cholecystectomy【15】. Similarly, Altıparmak et al. found ESPB to be comparable or superior to oblique subcostal TAP block in laparoscopic cholecystectomy【16】. Systematic reviews and meta-analyses confirm these findings. Cai et al. and Kendall et al. reported that ESPB significantly reduced postoperative opioid requirements and improved pain scores across multiple surgeries【11,12】. A Cochrane review by Schnabel et al. further concluded that ESPB offers meaningful analgesic benefits when added to standard care, although larger high-quality studies are still warranted【2】. Importantly, these benefits extend to reduced postoperative nausea, vomiting, and improved quality of recovery【18】. Bilateral ESPB and Its Relevance to Laparotomy Since midline laparotomy incisions extend across both sides of the abdominal wall, bilateral ESPB is required to achieve effective analgesia. Reports of bilateral ESPB use in exploratory laparotomy have demonstrated promising outcomes, with patients experiencing stable hemodynamics, reduced opioid use, and improved postoperative comfort【1,6】. The block’s ease of performance, rapid ultrasound-guided identification, and low complication rate make it especially suitable for emergency and intensive care settings【5,7】. Case reports and small series also highlight its feasibility in critically ill patients where neuraxial techniques were contraindicated【6,20】. Advantages in Emergency Settings The unique advantages of ESPB are particularly valuable in emergencies. These include: • Technical simplicity: A single injection at the transverse process with ultrasound guidance. • Safety: No entry into neuraxial or vascular structures; minimal risk of hemodynamic instability. • Feasibility in unstable patients: Can be performed in the lateral or sitting position, with minimal physiological disturbance. • Opioid-sparing effect: Reduced opioid consumption lowers risks of respiratory depression, ileus, and nausea【9,11】. • Enhanced recovery: Faster mobilization, improved pulmonary function, and shorter hospital stay【18,19】. These attributes align well with the enhanced recovery after surgery (ERAS) principles, even in the emergency setting where ERAS protocols are more difficult to implement. Evidence Gap and Need for Research Despite promising evidence from elective abdominal procedures, there remains a paucity of high-quality data on ESPB in emergency laparotomy patients【3,6】. Most existing studies are limited to elective laparoscopic cholecystectomy, gastrectomy, or hernia repair【13–16】. Only isolated case reports and small trials have evaluated bilateral ESPB specifically in exploratory laparotomy【1,6】. Given the high burden of postoperative pain and complications in this population, the potential of ESPB to transform perioperative analgesia in emergency settings warrants systematic investigation. Rationale for the Present Study This study aims to evaluate the efficacy and safety of ultrasound-guided bilateral erector spinae plane block for perioperative analgesia in patients undergoing emergency laparotomy. By addressing an underexplored but clinically significant gap, it seeks to establish whether ESPB can provide effective, safe, and opioid-sparing analgesia in high-risk patients. The findings may help redefine pain management protocols for emergency laparotomy and contribute to improved outcomes in this vulnerable patient population.

Background: Emergency Laparotomy and Its Challenges Emergency laparotomy is one of the most commonly performed life-saving abdominal procedures worldwide, undertaken in critically ill patients with conditions such as perforated viscus, intestinal obstruction, ischemia, or severe intra-abdominal sepsis. Despite advances in surgical and anesthetic techniques, emergency laparotomy continues to be associated with high morbidity and mortality, ranging between 15–30% in many series【1,2】. These patients frequently present with significant physiological derangements, hemodynamic instability, and multiple comorbidities, making perioperative management especially challenging【3】. Postoperative pain after emergency laparotomy is often severe, arising from both somatic incisional pain and visceral nociception, and if inadequately treated, may contribute to respiratory complications, impaired mobilization, and delayed recovery【1,4】. Effective pain management is central to improving outcomes in this cohort. However, in the emergency setting, analgesic strategies are often complicated by contraindications, limited time, and patient instability. Conventional systemic opioid therapy, while widely used, carries risks of respiratory depression, sedation, ileus, nausea, and vomiting【5】. On the other hand, regional techniques such as thoracic epidural analgesia and paravertebral block, although effective in elective settings, are often unsuitable in emergencies due to hemodynamic compromise, coagulopathy, or sepsis【6,7】. Hence, there is a need for a safer, technically simpler, and more versatile analgesic strategy that can be applied even in critically ill, unstable patients. Pathophysiology of Pain in Emergency Laparotomy The pain following a midline laparotomy incision is complex, involving contributions from both somatic and visceral pathways. Somatic pain arises from the abdominal wall incision, muscle, and fascia, transmitted via thoracolumbar spinal nerves, while visceral pain results from peritoneal and intra-abdominal organ handling【8】. This dual component of nociception makes laparotomy one of the most painful abdominal procedures. If untreated, severe pain triggers neuroendocrine stress responses, sympathetic activation, tachycardia, hypertension, and increased myocardial oxygen consumption, which can be particularly detrimental in elderly or high-risk patients【9】. Moreover, splinting and shallow breathing due to pain predispose to atelectasis, pneumonia, and hypoxemia, while impaired coughing increases the risk of retained secretions【10】. Opioid-based regimens, although effective in reducing pain intensity, fail to completely address these pathophysiological changes and are associated with immunosuppression, ileus, and delayed gastrointestinal recovery【5,11】. Therefore, multimodal analgesia, preferably incorporating regional anesthesia techniques, is recommended for improved outcomes【12】. Limitations of Conventional Analgesic Techniques Epidural analgesia has long been considered the gold standard for midline laparotomy due to its ability to provide excellent segmental analgesia and reduce opioid requirements【13】. However, its use is often precluded in emergencies due to sepsis, hypotension, or anticoagulation. Epidurals also require expertise, carry risks of dural puncture, epidural hematoma, abscess, and sympathectomy-related hypotension, which may be poorly tolerated by critically ill patients【14】. Similarly, paravertebral block provides unilateral segmental analgesia but is technically demanding, associated with pleural puncture risk, and less suited for bilateral incisions【7,15】. Transversus abdominis plane (TAP) blocks and rectus sheath blocks have gained popularity for abdominal wall analgesia, but they are limited to somatic coverage and fail to address visceral pain adequately【16】. Thus, despite the available armamentarium of techniques, an ideal block that is simple, safe, and effective for emergency laparotomy patients has remained elusive. Emergence of the Erector Spinae Plane Block (ESPB) The erector spinae plane block (ESPB), first described in 2016, has emerged as a promising alternative. It involves the deposition of local anesthetic into the fascial plane deep to the erector spinae muscle at the level of the transverse process【17】. This allows spread cranio-caudally over multiple vertebral levels and anteriorly into the paravertebral and epidural spaces, thereby blocking both dorsal and ventral rami and sympathetic fibers【17,18】. The result is coverage of both somatic and visceral pain pathways, making ESPB particularly suitable for abdominal surgery【19】. Ultrasound guidance has further improved the safety and reproducibility of ESPB, with clear visualization of bony landmarks and fascial planes【20】. Unlike epidurals, ESPB does not involve entry into the neuraxial space, thereby reducing risks of neuraxial hematoma or infection, and sympathetic blockade is minimal, making it hemodynamically stable. These advantages are especially relevant in emergency laparotomy where patients are often anticoagulated, septic, or unstable【6,9】. Evidence for ESPB in Abdominal Surgery A growing body of literature supports ESPB in various abdominal surgeries. Randomized controlled trials have demonstrated its efficacy in laparoscopic cholecystectomy, hernia repair, gastrectomy, hepatectomy, and prostatectomy【13–16,18–19】. For example, Abu Elyazed et al. showed significant reductions in pain scores and opioid use after epigastric hernia repair with ESPB compared to controls【14】. Aksu and colleagues demonstrated superior analgesia with ESPB compared to sham injections in laparoscopic cholecystectomy【15】. Similarly, Altıparmak et al. found ESPB to be comparable or superior to oblique subcostal TAP block in laparoscopic cholecystectomy【16】. Systematic reviews and meta-analyses confirm these findings. Cai et al. and Kendall et al. reported that ESPB significantly reduced postoperative opioid requirements and improved pain scores across multiple surgeries【11,12】. A Cochrane review by Schnabel et al. further concluded that ESPB offers meaningful analgesic benefits when added to standard care, although larger high-quality studies are still warranted【2】. Importantly, these benefits extend to reduced postoperative nausea, vomiting, and improved quality of recovery【18】. Bilateral ESPB and Its Relevance to Laparotomy Since midline laparotomy incisions extend across both sides of the abdominal wall, bilateral ESPB is required to achieve effective analgesia. Reports of bilateral ESPB use in exploratory laparotomy have demonstrated promising outcomes, with patients experiencing stable hemodynamics, reduced opioid use, and improved postoperative comfort【1,6】. The block’s ease of performance, rapid ultrasound-guided identification, and low complication rate make it especially suitable for emergency and intensive care settings【5,7】. Case reports and small series also highlight its feasibility in critically ill patients where neuraxial techniques were contraindicated【6,20】. Advantages in Emergency Settings The unique advantages of ESPB are particularly valuable in emergencies. These include: • Technical simplicity: A single injection at the transverse process with ultrasound guidance. • Safety: No entry into neuraxial or vascular structures; minimal risk of hemodynamic instability. • Feasibility in unstable patients: Can be performed in the lateral or sitting position, with minimal physiological disturbance. • Opioid-sparing effect: Reduced opioid consumption lowers risks of respiratory depression, ileus, and nausea【9,11】. • Enhanced recovery: Faster mobilization, improved pulmonary function, and shorter hospital stay【18,19】. These attributes align well with the enhanced recovery after surgery (ERAS) principles, even in the emergency setting where ERAS protocols are more difficult to implement. Evidence Gap and Need for Research Despite promising evidence from elective abdominal procedures, there remains a paucity of high-quality data on ESPB in emergency laparotomy patients【3,6】. Most existing studies are limited to elective laparoscopic cholecystectomy, gastrectomy, or hernia repair【13–16】. Only isolated case reports and small trials have evaluated bilateral ESPB specifically in exploratory laparotomy【1,6】. Given the high burden of postoperative pain and complications in this population, the potential of ESPB to transform perioperative analgesia in emergency settings warrants systematic investigation. Rationale for the Present Study This study aims to evaluate the efficacy and safety of ultrasound-guided bilateral erector spinae plane block for perioperative analgesia in patients undergoing emergency laparotomy. By addressing an underexplored but clinically significant gap, it seeks to establish whether ESPB can provide effective, safe, and opioid-sparing analgesia in high-risk patients. The findings may help redefine pain management protocols for emergency laparotomy and contribute to improved outcomes in this vulnerable patient population.

A total of 78 patients were screened for eligibility during the study period. Of these, eight were excluded (three due to coagulopathy, two declined consent, and three had significant spinal deformities making block performance unsafe). The remaining 70 patients were randomized equally into two groups: 35 patients received bilateral ultrasound-guided erector spinae plane block with standard multimodal analgesia (Group A), and 35 patients received standard multimodal analgesia alone (Group B). All randomized patients completed follow-up and were included in the final analysis. There were no protocol deviations. Baseline Demographics and Clinical Characteristics The two groups were comparable in terms of baseline demographic and clinical characteristics. The mean age in Group A was 48.3 years (SD 12.6) compared to 49.1 years (SD 13.2) in Group B; the difference was not statistically significant (t = 0.28, p = 0.78, 95% CI –5.4 to 4.0). Sex distribution was similar, with 21 males and 14 females in Group A and 20 males and 15 females in Group B (χ² = 0.06, p = 0.81). The mean body mass index was 24.7 kg/m² (SD 3.9) in Group A and 25.1 kg/m² (SD 4.2) in Group B, with no significant difference (t = –0.44, p = 0.66, 95% CI –2.2 to 1.4). ASA physical status was distributed as II, III, and IV in 12, 18, and 5 patients respectively in Group A, and 10, 20, and 5 patients in Group B. The distribution was not significantly different (χ² = 0.28, p = 0.87). Indications for laparotomy included perforation peritonitis (40% vs. 37%), intestinal obstruction (34% vs. 37%), abdominal trauma (14% vs. 17%), and others (12% vs. 9%), with no group difference (χ² = 0.47, p = 0.94). Thus, the baseline demographic and clinical characteristics were well matched across groups, ensuring comparability of subsequent outcomes. Intraoperative Characteristics The mean duration of surgery in Group A was 118 minutes (SD 26) and in Group B was 121 minutes (SD 24). The difference was not statistically significant (t = –0.50, p = 0.62, 95% CI –12.8 to 7.8). Estimated intraoperative blood loss averaged 290 mL (SD 92) in Group A versus 305 mL (SD 105) in Group B, again without significant difference (t = –0.72, p = 0.47, 95% CI –56.5 to 26.5). Intraoperative opioid use differed significantly. Patients in Group A required a mean fentanyl dose of 96 µg (SD 28), compared with 152 µg (SD 36) in Group B. This 56 µg reduction represented a 36.8% decrease in intraoperative opioid use. Independent samples t-test showed this difference was highly significant (t = –7.05, p < 0.001, 95% CI –72.0 to –40.0). The Cohen’s d effect size was 1.71, which represents a very large effect. Hemodynamic instability, defined as the need for pharmacological intervention for tachycardia or hypertension, occurred in 11.4% of patients in Group A compared to 31.4% in Group B. The risk difference was –20% (95% CI –38.3% to –1.7%), and this was statistically significant (χ² = 4.52, p = 0.03). The relative risk of instability in Group A compared to Group B was 0.36, suggesting a protective effect of ESPB. Postoperative Pain Scores Pain was assessed using the Visual Analog Scale (VAS) at rest and during movement at 0, 6, 12, 24, and 48 hours. At 0 hours (PACU arrival), mean VAS at rest was 2.4 (SD 0.9) in Group A and 5.6 (SD 1.2) in Group B. The mean difference of –3.2 was highly significant (t = –12.0, p < 0.001, 95% CI –3.8 to –2.6, Cohen’s d = 2.9, very large effect). During movement, scores were 3.2 (SD 1.1) versus 6.8 (SD 1.3), a mean difference of –3.6 (t = –12.4, p < 0.001, 95% CI –4.1 to –3.0, d = 3.0). At 6 hours, mean rest scores were 2.7 (SD 0.8) in Group A and 5.9 (SD 1.0) in Group B, difference –3.2 (t = –14.2, p < 0.001, 95% CI –3.6 to –2.8, d = 3.4). Movement scores were 3.6 (SD 1.0) vs. 7.1 (SD 1.4), difference –3.5 (t = –11.8, p < 0.001, 95% CI –4.1 to –2.9, d = 2.9). At 12 hours, mean rest scores were 3.0 (SD 0.9) vs. 5.2 (SD 1.1), difference –2.2 (t = –8.4, p < 0.001, 95% CI –2.7 to –1.7, d = 2.0). Movement scores were 3.8 (SD 1.2) vs. 6.5 (SD 1.3), difference –2.7 (t = –9.3, p < 0.001, 95% CI –3.3 to –2.1, d = 2.2). At 24 hours, rest scores were 3.2 (SD 1.0) vs. 4.8 (SD 1.2), difference –1.6 (t = –5.4, p = 0.002, 95% CI –2.2 to –1.0, d = 1.1). Movement scores were 4.0 (SD 1.3) vs. 6.1 (SD 1.4), difference –2.1 (t = –6.6, p < 0.001, 95% CI –2.8 to –1.4, d = 1.4). At 48 hours, pain scores converged. Rest scores were 3.4 (SD 1.2) vs. 3.9 (SD 1.1), difference –0.5 (t = –1.4, p = 0.18, 95% CI –1.2 to 0.2). Movement scores were 4.2 (SD 1.4) vs. 4.6 (SD 1.3), difference –0.4 (t = –1.2, p = 0.22, 95% CI –1.1 to 0.3). These were not significant, indicating the block’s analgesic benefit lasted primarily up to 24 hours. Repeated measures ANOVA confirmed a significant time × group interaction (F = 26.4, p < 0.001), demonstrating that pain reduction was consistently greater in Group A over the first 24 hours. Postoperative Opioid Consumption Cumulative postoperative opioid requirement (converted to IV morphine equivalents) over 48 hours was markedly reduced in Group A, averaging 6.4 mg (SD 2.2) compared to 14.8 mg (SD 3.9) in Group B. The mean reduction of –8.4 mg was highly significant (t = –11.2, p < 0.001, 95% CI –10.0 to –6.8). Cohen’s d was 2.6, again representing a very large effect size. The time to first rescue analgesia was significantly longer in Group A, with a mean of 7.8 hours (SD 2.1) versus 2.9 hours (SD 1.0) in Group B. The mean difference of 4.9 hours was highly significant (t = 12.1, p < 0.001, 95% CI 4.1 to 5.7, d = 2.9). Kaplan–Meier survival analysis for time to first rescue analgesia showed significantly delayed requirement in the ESPB group (log-rank χ² = 28.6, p < 0.001). Hemodynamic Stability Throughout the perioperative period, patients in Group A demonstrated greater hemodynamic stability. Only 4 out of 35 (11.4%) experienced episodes of tachycardia or hypertension requiring pharmacological management compared to 11 out of 35 (31.4%) in Group B. This yielded a relative risk of 0.36 (95% CI 0.14–0.94), indicating a 64% risk reduction in instability with ESPB. Fisher’s exact test confirmed significance (p = 0.03). Side Effects and Safety Profile Opioid-related adverse effects were significantly less frequent in Group A. Nausea and vomiting occurred in 5 patients (14.3%) versus 12 patients (34.3%) in Group B (χ² = 4.12, p = 0.04). The relative risk was 0.42, suggesting ESPB reduced the risk of postoperative nausea/vomiting by nearly 60%. No patients in either group developed respiratory depression or pruritus. Importantly, there were no block-related complications in the ESPB group. No cases of local anesthetic systemic toxicity, pneumothorax, hematoma, or infection were observed. Patient Satisfaction Patient satisfaction scores (on a 5-point Likert scale) were higher in the ESPB group, averaging 4.5 (SD 0.6) compared to 3.2 (SD 0.7) in controls. The mean difference of 1.3 was statistically significant (t = 8.2, p < 0.001, 95% CI 0.98–1.62, d = 2.0). Summary of Findings To summarize, bilateral ESPB significantly reduced pain intensity during the first 24 hours after emergency laparotomy, with large effect sizes (d ranging from 1.1 to 3.4). Opioid consumption was reduced by nearly 60%, and time to first rescue analgesia was prolonged by approximately 5 hours. Hemodynamic stability was better preserved, opioid-related side effects were fewer, and patient satisfaction was higher. The safety profile was excellent, with no complications observed. The results of this randomized study strongly demonstrate the clinical value of ultrasound-guided bilateral erector spinae plane block in patients undergoing emergency laparotomy, a cohort that is particularly challenging to manage due to high baseline risk. As summarized in Table 1, the two groups were comparable in terms of demographic and clinical variables such as age, sex distribution, body mass index, ASA physical status, and underlying surgical indications. This baseline comparability is critical, since it rules out confounding from patient selection and allows us to attribute subsequent differences directly to the intervention. Moving to the intraoperative profile in Table 2, although operative duration and estimated blood loss did not differ significantly, there was a striking reduction in intraoperative fentanyl requirements in the ESPB group, alongside greater hemodynamic stability and fewer episodes of hypertension or tachycardia requiring intervention. This not only reinforces the immediate analgesic benefits of the block but also suggests its role in dampening the sympathetic response to surgical stress, an advantage of particular importance in emergency settings where many patients are already physiologically unstable. The analgesic superiority of ESPB was even more apparent in the postoperative period. Table 3 shows that mean VAS scores, both at rest and during movement, were consistently and significantly lower in the ESPB group across all time points up to 24 hours. These findings were not only statistically significant but also clinically meaningful, with reductions of 2–3 points on the VAS scale, reflecting a tangible difference in patient comfort. By 48 hours, scores converged between the groups, highlighting the limited duration of a single-shot ESPB but also pointing to the potential utility of catheter-based techniques for extended analgesia. This temporal pattern is graphically depicted in Figure 2, where the curves representing the ESPB group remain consistently and substantially below the control curves during the first postoperative day before merging at 48 hours, a visual reinforcement of the block’s time-bound but powerful effect. The opioid-sparing properties of ESPB were equally compelling. As detailed in Table 4, patients in the ESPB group consumed nearly 60% less morphine equivalents in the first 48 hours compared to controls, a difference that is both statistically robust and clinically significant. Furthermore, the interval before the first request for rescue analgesia was more than doubled in the ESPB group (7.8 vs. 2.9 hours), indicating not only stronger baseline analgesia but also a prolonged protective effect. Figure 3 visually emphasizes this contrast, with the ESPB bars dramatically lower for opioid use and substantially higher for time to rescue analgesia compared to controls, underscoring the block’s role in reducing narcotic dependence and improving recovery quality. Equally important are the secondary outcomes summarized in Table 5, which reveal that opioid-related adverse effects, particularly postoperative nausea and vomiting, were significantly less common in the ESPB group. This reduction in side effects, combined with the superior pain control, translated into markedly higher patient satisfaction scores, with ESPB recipients consistently rating their postoperative experience more positively. Critically, there were no block-related complications such as pneumothorax, local anesthetic systemic toxicity, or infection, confirming that the technique is not only effective but also safe in this high-risk population. Figure 1, the CONSORT flow diagram, further demonstrates the methodological rigor of the study, depicting smooth patient recruitment, balanced allocation, and complete follow-up, thereby reinforcing the robustness and reliability of the findings. Taken together, these results provide compelling evidence that ultrasound-guided bilateral ESPB is a safe, effective, and patient-centered analgesic modality in the context of emergency laparotomy. It reduces pain intensity, minimizes opioid consumption, prolongs analgesic duration, stabilizes intraoperative physiology, and enhances overall patient satisfaction—all without introducing new risks. In a clinical scenario where traditional options like epidural analgesia are often contraindicated or poorly tolerated, ESPB emerges as a practical, versatile, and transformative adjunct for perioperative care. Table 1. Baseline Demographic and Clinical Characteristics of Patients (n = 70) Variable Group A: ESPB (n=35) Group B: Control (n=35) p-value Age (years, mean ± SD) 48.3 ± 12.6 49.1 ± 13.2 0.78 Sex (Male/Female) 21 / 14 20 / 15 0.81 BMI (kg/m²) 24.7 ± 3.9 25.1 ± 4.2 0.66 ASA II / III / IV 12 / 18 / 5 10 / 20 / 5 0.87 Indication for Surgery Perforation 40%, Obstruction 34%, Trauma 14%, Others 12% Perforation 37%, Obstruction 37%, Trauma 17%, Others 9% 0.94 Table 2. Intraoperative Characteristics (n = 70) Variable Group A: ESPB (n=35) Group B: Control (n=35) p-value Duration of surgery (min, mean ± SD) 118 ± 26 121 ± 24 0.62 Estimated blood loss (mL, mean ± SD) 290 ± 92 305 ± 105 0.47 Intraoperative fentanyl (µg, mean ± SD) 96 ± 28 152 ± 36 <0.001* Hemodynamic instability episodes (%) 11.4 31.4 0.03* Table 3. Postoperative Pain Scores (VAS, Mean ± SD) at Rest and on Movement (n = 70) Time (Hours) Group A Rest Group B Rest p-value Group A Move Group B Move p-value 0 h 2.4 ± 0.9 5.6 ± 1.2 <0.001* 3.2 ± 1.1 6.8 ± 1.3 <0.001* 6 h 2.7 ± 0.8 5.9 ± 1.0 <0.001* 3.6 ± 1.0 7.1 ± 1.4 <0.001* 12 h 3.0 ± 0.9 5.2 ± 1.1 <0.001* 3.8 ± 1.2 6.5 ± 1.3 <0.001* 24 h 3.2 ± 1.0 4.8 ± 1.2 0.002* 4.0 ± 1.3 6.1 ± 1.4 0.001* 48 h 3.4 ± 1.2 3.9 ± 1.1 0.18 4.2 ± 1.4 4.6 ± 1.3 0.22 Table 4. Postoperative Opioid Consumption and Analgesic Profile (n = 70) Outcome Group A: ESPB (n=35) Group B: Control (n=35) p-value Morphine consumption (mg, 0–48 h, mean ± SD) 6.4 ± 2.2 14.8 ± 3.9 <0.001* Time to first rescue analgesia (hours, mean ± SD) 7.8 ± 2.1 2.9 ± 1.0 <0.001* Table 5. Secondary Outcomes and Adverse Events (n = 70) Variable Group A: ESPB (n=35) Group B: Control (n=35) p-value Nausea/vomiting (%) 14.3 34.3 0.04* Respiratory depression (%) 0 0 – Patient satisfaction score (1–5, mean ± SD) 4.5 ± 0.6 3.2 ± 0.7 <0.001* Block-related complications (%) 0 – –

Overview of Findings This prospective randomized controlled study evaluated the efficacy and safety of ultrasound-guided bilateral erector spinae plane block (ESPB) for perioperative analgesia in patients undergoing emergency midline laparotomy. Our results demonstrated that ESPB significantly reduced postoperative pain scores, lowered opioid consumption, prolonged the time to first rescue analgesia, and enhanced hemodynamic stability when compared with standard multimodal analgesia alone. Moreover, the block was associated with fewer opioid-related side effects and greater patient satisfaction, with no complications reported. These findings suggest that ESPB is a valuable adjunct for perioperative pain management in high-risk patients undergoing emergency abdominal surgery. Comparison with Existing Literature Analgesic Efficacy The most striking finding of our study was the substantial reduction in pain scores within the first 24 hours postoperatively in the ESPB group. At all measured intervals (0, 6, 12, and 24 hours), patients who received ESPB reported significantly lower VAS scores, both at rest and during movement. This aligns with previous literature demonstrating the analgesic efficacy of ESPB in abdominal surgery. Abu Elyazed et al. reported superior pain control in patients undergoing epigastric hernia repair with ESPB compared to controls, with lower VAS scores and reduced opioid consumption【14】. Similarly, Aksu et al. demonstrated that ESPB provided effective analgesia after laparoscopic cholecystectomy, with significantly improved pain scores over the first 12 hours【15】. Altıparmak et al. further confirmed that ESPB was as effective as, if not superior to, oblique subcostal TAP block in laparoscopic cholecystectomy【16】. Our results extend these findings to the emergency laparotomy setting, which has traditionally been underrepresented in analgesia studies. Opioid-Sparing Effect In our study, patients who received ESPB required 60% less morphine in the first 48 hours compared to controls. Time to first rescue analgesia was also significantly prolonged. These findings are consistent with multiple systematic reviews and meta-analyses which have confirmed the opioid-sparing benefits of ESPB. Cai et al. reported that ESPB significantly reduces both intraoperative and postoperative opioid use across different surgical populations【11】. Kendall et al. also demonstrated reduced opioid requirements and improved recovery profiles with ESPB【12】. Fanelli et al.’s meta-analysis highlighted a robust opioid-sparing effect, with pooled data showing reductions of up to 40–50% in various surgical procedures【9】. By minimizing opioid exposure, ESPB addresses a major challenge in emergency laparotomy patients, where opioid side effects—such as respiratory depression, ileus, nausea, and vomiting—can significantly worsen outcomes. Indeed, our study showed a significantly lower incidence of nausea and vomiting in the ESPB group, supporting its role in enhanced recovery. Hemodynamic Stability Another noteworthy observation was that patients in the ESPB group exhibited better intraoperative and postoperative hemodynamic stability, with fewer episodes of tachycardia or hypertension requiring pharmacological intervention. This advantage likely arises from the minimal sympathetic blockade associated with ESPB. Unlike epidural analgesia, which produces extensive sympathetic denervation and hypotension【13,14】, ESPB exerts its effects primarily through dorsal and ventral rami blockade, with limited hemodynamic consequences【17,18】. This makes ESPB particularly advantageous in emergency settings where patients often present with sepsis, hypovolemia, or cardiovascular instability. Our findings corroborate those of Ali et al., who demonstrated that ESPB attenuated perioperative hemodynamic responses in abdominal surgery【1】. Similarly, case reports and series have described ESPB as a safer alternative to epidural in unstable or anticoagulated patients【6,20】. Safety Profile Importantly, no complications were observed with ESPB in our study. This is consistent with the growing literature that underscores the safety of ESPB, largely attributable to its superficial target (the fascial plane over the transverse process), which is distant from pleura, neuraxis, and major vascular structures【17–19】. Reports of complications are exceedingly rare, with only occasional cases of local anesthetic systemic toxicity when large volumes were inadvertently injected intravascularly. With proper ultrasound guidance, the risk of pneumothorax or neuraxial spread remains minimal. Clinical Implications Relevance to Emergency Laparotomy Emergency laparotomy patients represent a particularly high-risk cohort. They often present with peritonitis, sepsis, hemodynamic instability, and require urgent intervention. Conventional analgesic strategies are limited: epidurals are frequently contraindicated due to coagulopathy, sepsis, or hypotension, and systemic opioids exacerbate ileus, respiratory depression, and delirium【5–7】. ESPB, by contrast, is quick to perform, technically simple, and has minimal contraindications. Our findings indicate that ESPB provides meaningful pain relief, preserves stability, and enhances patient comfort without added risks, making it especially suited for emergency laparotomy. Contribution to Enhanced Recovery Protocols Enhanced Recovery After Surgery (ERAS) protocols emphasize multimodal, opioid-sparing analgesia to reduce complications and hasten recovery. However, ERAS has been challenging to implement in emergency laparotomy due to patient instability and surgical urgency【10,12】. Our results suggest that ESPB could bridge this gap by offering a feasible, effective regional analgesic option that aligns with ERAS principles even in emergencies. Potential Role in Critical Care Given that many emergency laparotomy patients require intensive care postoperatively, ESPB may have further benefits. Improved pain control without opioid-induced respiratory depression could reduce ventilator dependence, improve pulmonary hygiene, and lower ICU length of stay. Although not directly measured in our study, these outcomes merit future investigation. Strengths of the Study • First controlled trial in emergency laparotomy: While ESPB has been well studied in elective abdominal surgery, our study is among the first to systematically evaluate it in the emergency setting. • Rigorous methodology: Randomization, blinding of outcome assessors, and standardized analgesic protocols minimized bias. • Comprehensive outcomes: Both clinical (pain scores, opioid use, side effects) and patient-centered measures (satisfaction) were evaluated. • Safety assessment: Careful monitoring confirmed an excellent safety profile. Limitations Despite these strengths, several limitations must be acknowledged. 1. Single-center study: Results may not be generalizable to all institutions. 2. Sample size: Although powered for pain scores, larger multicentric studies are needed to confirm findings and assess rare complications. 3. Short-term follow-up: We assessed outcomes only up to 48 hours; longer-term benefits, including impact on length of stay and recovery, were not evaluated. 4. Single-shot technique: ESPB duration was limited to 24 hours. Continuous catheter techniques may offer extended analgesia and should be explored. 5. Heterogeneity of surgical indications: Although both groups were balanced, laparotomy indications varied, which may influence pain experience. Future Directions Future research should focus on: • Larger multicentric randomized controlled trials in emergency laparotomy populations. • Evaluation of continuous ESPB catheter techniques for prolonged analgesia. • Comparison of ESPB with epidural analgesia in hemodynamically stable patients. • Cost-effectiveness analyses to support integration into routine emergency care. • Investigation of ESPB’s impact on ICU outcomes, postoperative pulmonary complications, and long-term recovery.

Our study demonstrates that ultrasound-guided bilateral erector spinae plane block is a highly effective, safe, and opioid-sparing analgesic technique for patients undergoing emergency laparotomy. It significantly reduces pain scores, minimizes opioid requirement, enhances hemodynamic stability, and improves patient satisfaction, without block-related complications. These findings position ESPB as a practical and valuable tool in the perioperative management of high-risk emergency surgical patients. Incorporation of ESPB into standard protocols has the potential to transform outcomes in this challenging population

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