For cases with a Tanaka Index of less than 0.25 (Figure 3), the choice of surgical procedure was determined by the location and size of the hernia. Depending on these factors, anterior component separation, retro-rectus repair, or onlay mesh repair was performed, with transverse abdominis release (TAR) being utilised only in select cases where the defect size exceeded 12 cm. These cases were not included in our study.

For patients with a Tanaka Index between 0.25 and 0.30, posterior component separation via TAR with retrorectus mesh was the preferred surgical approach. When the index ranged from 0.31 to 0.35, the former surgery was combined with an autologous peritoneal flap to facilitate fascial closure. In cases where the index exceeded 0.35, preoperative preparations with botulinum toxin (BT) and progressive preoperative pneumoperitoneum (PPP) were implemented based on reported outcomes and established indications for PPP from previous studies [9, 10, 13]. A pre-anesthetic evaluation was conducted for all patients, including an assessment of lung function. Patients were strictly advised to abstain from smoking and adhere to a weight loss regimen. Additionally, they were actively encouraged to perform incentive spirometry at 2-h intervals everyday. Informed consent was obtained from all patients undergoing the preoperative technique.

Botulinum toxin (BT) injection was administered as an outpatient procedure under ultrasound-guided infiltration 2 weeks prior to the PPP implementation, following the methodology described by Deerenberg EB et al [13]. The anatomical landmarks—costal margin and anterior superior iliac spine—were identified and marked. A line between these two landmarks, half-way between the anterior axillary line and the mid-clavicular line was drawn and divided into three equidistant segments.

A total of 300 units of botulinum toxin (BT) was reconstituted with 150 mL of normal saline, achieving a concentration of 2 units/mL. Under ultrasound guidance, the flat abdominal muscles were identified, and 25 mL of the solution was injected at each designated site, with approximately 8 mL administered into each muscle group. A total of 150 units was injected on each side of the abdomen. (Figures 4, 5). Pre- and post-Botox CT scans were obtained to assess the increased laxity of the lateral abdominal wall muscles, evidenced by their elongation (Figures 6, 7).

For the implementation of progressive preoperative pneumoperitoneum (PPP), as previously described by [9, 14] an intraperitoneal double-lumen catheter was inserted, preferably in the upper left quadrant, under ultrasound. This procedure was done 14 days after the BT injection when paralyzing effect reaches a maximum [15]. The insertion was performed via an anterolateral approach in an area free from scarring or previous incisions. Initially, a 22G spinal needle was introduced into the peritoneal cavity, ensuring that the tip just crossed the peritoneal space (Figure 8A). A total of 300 mL of unfiltered ambient air was then administered via a syringe, followed by a confirmatory CT scan (Figure 8B). The largest pocket of intraperitoneal air was identified, and an 8Fr pigtail catheter was subsequently placed into that space.

The total insufflation volume was calculated as approximately three times the visceral-intraperitoneal hernia (VIH) volume determined by CT imaging [12]. Progressive insufflation was performed daily or every other day, either in an inpatient or outpatient setting, for a minimum of 7 days, continuing until the day of surgery using a three-way valve. The average volume of insufflation was 800–1,000 mL per day, adjusted according to patient tolerance. Monitoring included assessing abdominal wall distension, discomfort, and dyspnoea, which served as indicators for cessation of insufflation. Complications pertaining to BT injection, such as injection site reactions (pain, swelling, redness or bruising), allergic reactions (itching, dyspnea) or weakened cough, and those to PPP such as shoulder pain, metabolic acidosis, subcutaneous emphysema, pneumothorax, pneumomediastinum, bowel perforation were monitored. A multidisciplinary team including general surgeons, anesthesiologists, and physiotherapists was involved in patient assessment and perioperative care.

Patients underwent surgery under general anaesthesia with epidural cover, and initial peak airway pressures (PAP) including P peak and P plateau were recorded, as a significant increase in PAP before the incision and following fascial closure could potentially lead to alveolar volutrauma [16].

All patients had abdominal wall reconstruction using the posterior component separation technique via transverse abdominis release (TAR), which was carried out unilaterally or bilaterally as per Reinpold et al [17], depending on intraoperative decisions made by the surgeon. Following midline incision, the sac is identified and dissected up to the fascial border of the hernial ring. The sac and peritoneum are then carefully mobilised from the fascial hernial ring, the posterior rectus sheath bilaterally, and the defect’s cephalad and caudal aspects along the linea alba. A longitudinal incision, approximately 0.5 cm medial to the neurovascular bundle, is made along the posterior rectus sheath, ensuring its preservation while allowing for the complete separation of the rectus abdominis muscle from the posterior rectus sheath up to the lateral edge of the rectus compartment. The retromuscular plane is subsequently developed towards the junction of the posterior and anterior rectus sheaths, creating a suitable space for further surgical reconstruction. Released Transversus Abdominis Muscle is pushed away to enter the space between the Transversus Abdominis muscle and Transversalis fascia. Inferiorly, the space of Retzius is entered and Cooper’s ligament visualized. Superiorly, the retro muscular plane can be extended cephalad to the xiphoid and diaphragm if needed.

For patients with a Tanaka Index exceeding 0.3, the “Swinging Door” technique, a peritoneal flap method, was employed alongside transverse abdominis release (TAR) [18, 19] (Figure 9A). This technique utilises excess tissue from the hernial sac to close the fascial defect, effectively enlarging the abdominal domain at the herniation site without weakening the lateral abdominal wall [20].

A 30 × 30 cm polypropylene mesh was placed in the underlay space to cover the defect, extending laterally into the retroperitoneum and secured with 2-0 Prolene sutures (Figure 9B). A Romovac negative suction drain tube was positioned over the mesh within the retrorectus plane to facilitate drainage. Finally, the anterior rectus sheath was meticulously closed to restore the linea alba.

Redundant skin and subcutaneous tissue were excised, and a second subcutaneous drain tube (DT) was inserted. The skin was then sutured without tension, and a tight compressive dressing was applied. An increase in Peak Airway Pressures was noted. A rise of >10 cm H₂O suggested imminent abdominal compartment syndrome [21]. As described by Novitsky in his book Hernia Surgery: Current Principles, the study standardized an increase of >8 cm H₂O (>6 mm Hg) as significant and continued patients on elective ventilation [22]. We vigilantly monitored intra-abdominal pressure for Abdominal Compartment Syndrome (ACS) using a Foley catheter and a central venous pressure (CVP) manometer, following the previously described technique in Rao P et al and Hunter JD et al [23, 24]. Serial readings of IAP were noted to identify early signs of ACS. Post Extubation, patients were advised to perform incentive spirometry and early ambulation. Epidural top-ups were given with tramadol till day 3. The DTs were removed on Post operative day 3 or if output was <25 mL/day, whichever occured later. Sutures were removed between Post operative days 10–14 in healthy wounds.

We considered various parameters, including age, sex, duration of hernia, past surgical history, smoking history, chronic medical conditions, and CT findings such as defect size and Tanaka Index. Additional factors assessed included intraoperative procedures, elevation in peak airway pressures, length of hospital stay, postoperative pain, postoperative complications (both local wound and systemic), date of discharge, postoperative follow-up, and recurrence rate.

A total of 50 patients with loss of domain (LOD) hernias were included in this study. Groups (I,II,III) were categorized based on Tanka Index (Table 2). The median age of the cohort was 52 years (range: 36–66 years), with a male-to-female ratio of 1:1.78 (Table 3). The median BMI and the duration of hernia amongst the patients was at an increasing trend across the 3 groups and the association was found to be statistically significant (p value < 0.001). Age, sex distribution, ASA classification, and number of prior surgeries did not differ significantly between groups. 28% (n = 14) were active smokers who were about 2.5 times less than nonsmokers (n = 36). Patients with hernia following just a single abdominal surgery was highest in Group I (n = 16), whilst Group III had the highest incidence of hernia following 3 surgeries (n = 4). Among the patients, all of whom have had a previous history of abdominal surgery, 44% (n = 22) had undergone an emergency laparotomy. 68% (n = 22) of females had history of Obstetric procedures. Preoperative comorbidities included hypertension (32%), diabetes mellitus (28%), and chronic obstructive pulmonary disease (12%). However, number of patients with preoperative comorbidities was more in Groups II and III.

As assessed on CT imaging, the median transverse defect size was increasing across the 3 groups. Among patients who received preoperative progressive pneumoperitoneum (PPP), the median air insufflation volume was 13 L.

All patients underwent posterior component separation with transverse abdominis release (TAR), with 26 patients (52%) requiring additional peritoneal flap augmentation. However only 12 of these 26 patients needed preoperative augmentation (Table 4). Intraoperative peak airway pressure (PAP) monitoring revealed significant difference (p value – 0.002), a median increase of 8.2 cm H₂O for Group II at the time of closure which was higher than other Groups (Table 4). The blood loss increased over the 3 groups and was statistically significant (p < 0.001). A significant rise in PAP (>8 cm H₂O) was noted in 26 patients (52%), all of whom required elective postoperative ventilation.

All patients were monitored from the postoperative day (POD) 0 for intra-abdominal pressure using a central venous pressure (CVP) manometer, which remained comparable across groups until POD 3 (all p > 0.2), with no values exceeding thresholds associated with abdominal compartment syndrome (ACS), suggesting the protocol was effective in mitigating this risk (Table 5). Patients who required elective postoperative ventilation (n = 26) were successfully weaned off within 48 h. However, the need for postoperative ventilator support was significantly higher in Group 2 (85.7%) compared to Group 1 (50%) and Group 3 (16.7%) (p = 0.002). With respect to complication, superficial surgical site infections (SSI) were seen only in groups 2 and 3 (14-17%) (Figure 10). Seromas were significantly more common in Group 3 (33.3%) versus Group 2 (14.3%) and absent in Group 1 (p = 0.014). Both these complications were managed conservatively. Systemic complications included acute respiratory distress syndrome, defined by acute onset, bilateral lung infiltrates on chest radiography or CT scan of a non-cardiac origin, and a PaO₂/FiO₂ ratio of less than 300 mm Hg with the requirement of positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) of greater than or equal to 5 cm H₂0, which occured in 8% of cases [25]. The other complication was transient acute kidney injury, defined as temporary decline in kidney function with a return to baseline values in 48 h, was noted in 4% of cases [26]. Both the complications occurred in Group II. The median length of hospital stay for group II was 12 days which was the highest among the groups. Overall, while defect size and disease severity increased with the Tanaka Index, the structured intraoperative and postoperative protocols effectively prevented ACS, although systemic complications and ventilator dependence were more frequent in intermediate-risk patients.

At a median follow-up of 12 months, 100% of patients achieved successful fascial closure without recurrence. One patient experienced recurrence during his 2-year follow-up who had a Tanaka Index of 0.34 at baseline. None of the patients required reoperation within the follow-up period. This study demonstrates that posterior component separation with TAR, with or without peritoneal flap augmentation, is an effective technique for LOD hernias. While preoperative interventions remain valuable, our algorithm for surgical planning based on defect size and intraoperative PAP monitoring proved to be a safe and effective alternative in resource-limited settings.

The value of a systematic strategy to the management of loss of domain (LOD) hernias has been demonstrated by this study. Customised preoperative and intraoperative techniques after classifying patients according to the Tanaka Index, greatly increased fascial closure rates and has shown no complications of abdominal compartment syndrome. Botulinum toxin injections and progressive preoperative pneumoperitoneum (PPP) enhanced abdominal compliance for very large hernias, enabling safer hernia repair.

For intra-abdominal hypertension, intraoperative airway pressure monitoring has been shown to be a trustworthy surrogate marker, enabling early intervention such as elective postoperative intubation, to avoid problems after surgery. Additionally, postoperative intra-abdominal pressure surveillance through Foley catheter measurements was critical in reducing morbidity.

Our findings show that a targeted, patient-specific strategy is both economical and successful. The long-term success of this approach is further supported by the lack of recurrence during a 1-year follow-up period. Future research should focus on validating these findings through larger multi-center studies and exploring additional cost-effective alternatives for preoperative preparation.