OBJECTIVE
To describe original technique of intercostal nerve cryoablation under trigger electromyographic control in patients undergoing thoracoabdominal aortic repair through thoracophrenolumbotomy for prevention of postoperative pain syndrome.
MATERIAL AND METHODS
The study included 24 patients with thoracic, thoracoabdominal aortic aneurysm and megaaorta. All patients underwent open surgical procedures involving intercostal nerve cryoablation under electromyography. After weaning from ventilator and throughout the first 10 days, as well as at discharge, we surveyed patients regarding pain syndrome. Pain in the thoracophrenolumbotomy area was assessed 3 times daily using the Numeric Rating Scale (NRS-11). Consumption of opioid and non-opioid analgesics was recorded. We estimated daily intake of opioid analgesics for each patient and converted into morphine milligram equivalents (MME). Complications and adverse events were documented. Follow-up interviews were conducted after 1 and 3 months to assess analgesic consumption, pain, side effects and persistence of cryoanalgesia effects.
RESULTS
In total, 156 intercostal nerves were scheduled for cryoablation throughout 58 sessions (mean 6.5 nerves per a patient). Mean time necessary for complete and simultaneous cessation of compound action potentials in 3 intercostal nerves at temperatures –130 —140 °C was 42.6±10.1 sec. On the first postoperative day, NRS-11 score was 4.65±1.87, MME — 11.8. These values decreased over time (NRS score 2.4±1.8 and MME 4.6 after 4 days, NRS score 1.2±0.95 and MME 1 after 8 days). No mortality, paraplegia or cryoablation-related adverse effects were observed. Intercostal nerves were successfully localized in 100% of cases using trigger electromyography with complete disappearance of action potentials in all cases. ICU-stay was 2.4 [1.6; 3.4] days, postoperative hospital-stay — 12 [8.5; 14.5] days. Cryoanalgesia effect persisted for several postoperative months without exteroceptive sensitivity in dermatomes corresponding to ablated nerves. No additional postoperative analgesia was required in any patient one month postoperatively.
CONCLUSION
Electromyography-guided intercostal nerve cryoablation is a safe and reproducible technique that can be recommended as an adjunct to systemic analgesia following thoracic, thoracoabdominal and total aortic repair. Original technique of ablation allows for optimization of the procedure and delivers effective analgesic effect.
