Opioid-Free Total Intravenous Anesthesia in a Schizophrenia Patient with Retrosternal Goiter

Abstract
Introduction

Schizophrenia patients on serotonergic antipsychotics risk serotonin syndrome (SS) with opioids or 5-HT3 antagonists, alongside postoperative delirium and respiratory compromise related to Opioids. Green anesthesia minimizes environmental risks.

Case report
A female in her early 40s with schizophrenia and type 2 diabetes, on Aripiprazole, Quetiapine and Trihexyphenidyl, underwent thyroidectomy for a retrosternal goiter using opioid-free Total Intravenous Anesthesia (TIVA), avoiding Granisetron to reduce SS risk. No tracheomalacia or PONV occurred; minimal analgesics were needed, declined post-op.

Discussion
This approach prevented SS, delirium, cognitive decline and respiratory complications by avoiding opioid and 5-HT3 receptor interactions.

Conclusion
Opioid-free TIVA is safe and sustainable for high-risk patients.

Keywords: Opioid-free TIVA, Green anesthesia, Serotonin syndrome, Postoperative delirium, Schizophrenia, Retrosternal goiter

Introduction
Schizophrenia patients on antipsychotics with 5-HT receptor activity (e.g., 5-HT1A agonism, 5-HT2A antagonism) face risks of serotonin syndrome (SS) with opioids like fentanyl or 5-HT3 antagonists like Granisetron¹. Opioids also increase postoperative delirium, cognitive decline and respiratory compromise, particularly in patients with airway challenges from retrosternal goiter^2,3. Schizophrenia patients often exhibit higher pain thresholds, possibly due to altered opioid or dopamine receptor function, reducing analgesic needs. Green anesthesia, avoiding volatile anesthetics and opioids, minimizes environmental and clinical risks⁴. This case report describes opioid-free TIVA in a female with schizophrenia, chosen to prevent SS, delirium, cognitive decline, respiratory compromise and pharmacokinetic interactions^1,4.

Case Presentation
A female in her early 40s with chronic schizophrenia, recurrent depression and type 2 diabetes, managed with Aripiprazole (partial 5-HT1A agonist, 5-HT2A antagonist), Quetiapine (5-HT2 antagonist) and Trihexyphenidyl (anticholinergic, minimal serotonergic activity), presented for elective thyroidectomy due to a retrosternal goiter. Ultrasound showed a multinodular goiter with bilateral large nodules and retrosternal extension; CT confirmed tracheal narrowing, indicating a difficult airway and risk of postoperative respiratory compromise, including tracheomalacia. Laboratory tests were normal and she was euthyroid. Opioid-free TIVA was selected, avoiding Granisetron, to prevent SS, delirium, cognitive decline, respiratory complications and pharmacokinetic interactions, leveraging her likely high pain threshold¹.

Anesthetic Management
• Pre-induction: Dexmedetomidine (12 µg IV), Glycopyrrolate (100 µg IV).
• Induction: Propofol (BIS <60), Ketamine (50 mg IV), Rocuronium (50 mg IV) after confirming mask ventilation; Sugammadex was available. A 50 mg dose of ketamine achieves NMDA receptor saturation, as described by Friedberg5.
• Airway: Failed 7.0 tube as airway narrowing; 6.5 tube placed via video laryngoscope, ventilation confirmed without trauma.
• Block: US guided Bilateral superficial cervical plexus block.
• Maintenance: Propofol (BIS 40-60), Dexmedetomidine (12 µg IV), stable hemodynamics (BP 110–140 mmHg) over 3 hours.
• Emergence: Propofol stopped 5 minutes pre-extubation; patient oriented within 5 minutes.
• Analgesia: Paracetamol (1 g IV) and Lornoxicam (8 mg IV) 15 minutes before surgery end; no analgesics needed in recovery; offered but declined on postoperative days 1 and 2, consistent with a high pain threshold.
• PONV prophylaxis: Granisetron avoided to minimize SS risk; no PONV during 1.5-day hospital stay, no antiemetics required.
No tracheomalacia was observed post-op. The patient recovered without respiratory, pain or cognitive complications, reporting feeling calm pre-surgery, with no postoperative pain, nausea or confusion and resumed daily activities smoothly.

Discussion
This case demonstrates opioid-free TIVA efficacy in a female with schizophrenia undergoing thyroidectomy for a retrosternal goitre. The multimodal approach-Propofol, Dexmedetomidine, Ketamine and regional analgesia-ensured stable hemodynamic, effective analgesia and rapid recovery without serotonin syndrome (SS), postoperative delirium, cognitive decline or respiratory complications, including tracheomalacia. The patient’s antipsychotics, Aripiprazole (partial 5-HT1A agonist, 5-HT2A antagonist) and Quetiapine (5-HT2 antagonist), increased SS risk, necessitating avoidance of opioids and Granisetron to minimize 5-HT receptor interactions, respiratory compromise and pharmacokinetic interactions^1,6,7.

SS is a critical risk with opioids like fentanyl, which has mild serotonin reuptake inhibition¹. Case reports document SS in schizophrenia patients, including a male on Paroxetine developing SS after fentanyl post-tracheostomy⁵ and another on sertraline and Aripiprazole post-fentanyl during surgery⁷. Aripiprazole and Quetiapine’s 5-HT activity, unlike Trihexyphenidyl’s minimal effects, amplifies SS risk and Granisetron’s 5-HT3 antagonism could theoretically exacerbate this¹. No PONV occurred during the 1.5-day hospital stay, supporting Granisetron avoidance.

Postoperative delirium and cognitive decline are concerns in schizophrenia patients. A systematic review linked meperidine to delirium, with other opioids showing inconsistent effects². A cohort study found low opioid doses increased delirium risk (RR 5.4, 95% CI 2.4-12.3), suggesting undertreated pain as a factor³. An ICU study associated higher opioid doses with delirium⁸. Meta-analyses confirm delirium predicts cognitive decline, with schizophrenia patients at higher risk^9,10. Opioids also risk respiratory depression, critical in retrosternal goitre cases⁸.

The patient required only intraoperative Paracetamol (1 g IV) and Lornoxicam (8 mg IV), declining further analgesics, likely due to a high pain threshold common in schizophrenia, possibly from altered opioid or dopamine receptor function. Ketamine’s 50 mg dose achieved NMDA receptor saturation, providing effective analgesia without serotonergic or respiratory effects, as noted by Friedberg⁶. Dexmedetomidine reduced delirium risk¹¹, while the cervical plexus block and BIS-guided Propofol minimized analgesic and delirium risks⁴. The absence of SS, delirium, cognitive decline, tracheomalacia and PONV supports this approach’s efficacy. As green anaesthesia, it avoided volatile anaesthetics, reducing environmental impact⁴. This case advocates for opioid-free protocols in psychiatric patients with airway challenges, considering 5-HT receptor interactions and pharmacokinetics^1,11,4.

Conclusion
Opioid-free TIVA is a safe, sustainable strategy for schizophrenia patients, preventing SS, delirium, cognitive decline and respiratory complications by avoiding 5-HT receptor interactions^1,11,4.

Learning points
Opioid-free TIVA is effective for schizophrenia patients on serotonergic medications undergoing major surgery.
Avoiding opioids and 5-HT3 antagonists like Granisetron prevents SS, delirium, cognitive decline and respiratory compromise^1,6,7.
Multimodal analgesia (e.g., Paracetamol, Lornoxicam, regional blocks) ensures pain control, especially with high pain thresholds in schizophrenia.
Dexmedetomidine and BIS-guided sedation minimize delirium risk^11,4.
Preoperative planning, including airway assessment and pharmacokinetic considerations, is critical for retrosternal goiter cases¹.

References
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