Local infiltration anesthesia combined with S-ketamine for cesarean delivery in a parturient with diaphragmatic hernia and severe scoliosis: a case report

Technical Summary: Local Infiltration Anesthesia Combined with S-Ketamine for Cesarean Delivery in a High-Risk Parturient

Problem Statement
The management of cesarean delivery in parturients with complex comorbidities presents significant anesthetic challenges. This case report addresses a 23-year-old primipara (36 weeks, 4 days gestation) suffering from severe poliomyelitis-associated kyphoscoliosis, diaphragmatic hernia, and restrictive lung disease. The patient's condition rendered standard anesthetic modalities unfeasible or high-risk:

• General Anesthesia (GA): Contraindicated due to a high probability of difficult endotracheal intubation (Mallampati Class 3, limited mouth opening), severe restrictive lung disease increasing the risk of hypoxemia during mechanical ventilation, and heightened sensitivity to neuromuscular blocking agents due to poliomyelitis history. Furthermore, GA carries risks of worsening the diaphragmatic hernia via muscle relaxation, potentially leading to mediastinal shift and cardiac arrest.
• Neuraxial Anesthesia: Technically unfeasible due to severe S-shaped thoracolumbar deformity and vertebral rotation, which prevented accurate localization of intervertebral spaces even with ultrasound guidance. Additionally, there were concerns regarding unpredictable anesthetic spread, potential nerve injury, and the vulnerability of poliomyelitis-affected motor neurons to local anesthetic neurotoxicity.
• Abdominal Regional Blocks (TAP/QLB): Contraindicated because the patient's abdominal wall was extremely thin (skin-to-peritoneum distance of 1.34 cm), posing a high risk of visceral injury during needle insertion, and the quadratus lumborum muscle could not be visualized via ultrasound.

Methodology
The medical team opted for local infiltration anesthesia combined with intravenous S-ketamine sedation, a technique rarely reported for cesarean delivery in the past two decades. The procedure involved the following steps:

1. Preoperative Preparation: The patient declined GA, neuraxial anesthesia, and TAP blocks after full risk counseling.
2. Sedation and Analgesia: Prior to skin incision, 10 mg of intravenous S-ketamine was administered.
3. Local Infiltration: 10 mL of 0.5% lidocaine was infiltrated around the surgical incision site.
4. Surgical Execution: Due to the thin abdominal wall, the incision was made directly into the peritoneal cavity.
5. Intraoperative Management:
   • An additional 10 mg of S-ketamine was administered to manage peritoneal traction responses.
   • Spontaneous ventilation was maintained throughout the procedure.
   • Post-fetal delivery, a further 10 mg of S-ketamine was given, followed by a continuous infusion of dexmedetomidine (0.4 µg/kg/h).
6. Monitoring: Peripheral oxygen saturation was continuously monitored, and the patient was observed for respiratory depression and pain scores.

Results
The cesarean delivery was completed successfully with the following outcomes:

• Maternal Status: The patient maintained spontaneous ventilation with oxygen saturation levels between 95% and 99%. She remained hemodynamically stable with an estimated blood loss of 400 mL. Postoperatively, she regained full consciousness within 20 minutes, reported a Visual Analog Scale (VAS) pain score of 0, and experienced no intraoperative recall or incision pain. No additional analgesics or nerve blocks were required.
• Neonatal Status: A healthy male infant (2810 g) was delivered with Apgar scores of 9 and 10 at 1 and 5 minutes, respectively.
• Recovery: Both mother and infant were discharged on postoperative day 5 without complications.

Key Contributions
This case report demonstrates that local infiltration anesthesia combined with S-ketamine is a viable, safe, and effective alternative for cesarean delivery in patients where:

1. General anesthesia poses life-threatening risks (e.g., difficult airway, severe pulmonary compromise).
2. Neuraxial anesthesia is anatomically impossible or carries excessive risk of neurological injury.
3. Peripheral nerve blocks (such as TAP or QLB) are contraindicated due to anatomical constraints (e.g., extremely thin abdominal walls).

The authors highlight that S-ketamine is particularly suitable in this context because it provides satisfactory sedation and analgesia with minimal respiratory depression while preserving protective airway reflexes (cough, gag, swallowing), thereby mitigating the risk of aspiration in patients with diaphragmatic hernia.

Significance and Claims
The paper claims that for parturients with multiple severe comorbidities, the "simplest anesthetic techniques can often yield optimal outcomes." The authors argue that local infiltration anesthesia should not be overlooked as a viable alternative in high-risk scenarios where conventional methods fail. The successful management of this complex case underscores the importance of carefully weighing risks and benefits to select an anesthetic strategy that prioritizes patient safety over technical complexity. The report concludes that this approach offers a valuable option for a specific subset of high-risk patients who would otherwise face prohibitive anesthetic risks.