Zhang Ruoyu, Schwabe Kerstin, Krüger Marcus, Haverich Axel, Krauss Joachim K, Alam Mesbah
Department of Thoracic Surgery, Center for Pneumology and Thoracic Surgery, Schillerhoehe Hospital, Gerlingen, Germany.
Section of Neurosurgery, Department of Surgery, Hannover Medical School, Hannover, Germany.
J Thorac Dis. 2017 Aug;9(8):2461-2465. doi: 10.21037/jtd.2017.07.10.
Although intercostal nerve injury is one of the major causes for post-thoracotomy pain, the exact mechanisms are still unclear. We sought to evaluate the electro-physiological changes of intercostal nerve injury after thoracotomy in a sheep model.
Adult sheep underwent thoracotomy in the sixth intercostal space by employing diathermy to superior border of the seventh rib. In two sheep, ribs were then spread using retractor spreading for a distance of 7 cm for 30 minutes. In the third sheep, thoracotomy was followed by harvesting intercostal muscles including the neurovascular bundle adjacent to inferior edge of the sixth rib. Thereafter, ribs were spread in the same way, but with the muscle flap dangled between the blades for intercostal nerve protection (dangling muscle flap technique). The nerve conduction velocity of the intercostal nerve was recorded before and after incision of intercostal muscles, immediately and 30 minutes after retractor placement and 30 minutes after removal of the retractor.
In the sheep undergoing conventional thoracotomy, the physiological conductivity of intercostal nerve was completely blocked immediately after retractor placement using the same stimulation intensity or even the supra-threshold intensity. The conduction block persisted for 30 minutes during the retractor placement and further 30 minutes after removal of the retractor. In contrast, intercostal nerve conduction was not impaired throughout the experiment with the dangling muscle flap technique.
Our experiment provides electro-physiological evidence for intercostal nerve injury after thoracotomy. The injury is primarily attributed to mechanical compression caused by the rib retractor.
尽管肋间神经损伤是开胸术后疼痛的主要原因之一,但其确切机制仍不清楚。我们试图在绵羊模型中评估开胸术后肋间神经损伤的电生理变化。
成年绵羊在第七肋上缘采用透热法在第六肋间进行开胸手术。在两只绵羊中,然后使用牵开器将肋骨撑开7厘米,持续30分钟。在第三只绵羊中,开胸术后切除包括第六肋下缘相邻的神经血管束在内的肋间肌。此后,以同样的方式撑开肋骨,但将肌瓣悬垂在刀片之间以保护肋间神经(悬垂肌瓣技术)。在切开肋间肌之前和之后、放置牵开器后立即和30分钟以及移除牵开器后30分钟记录肋间神经的神经传导速度。
在接受传统开胸手术的绵羊中,使用相同的刺激强度甚至阈上强度,在放置牵开器后立即完全阻断了肋间神经的生理传导性。在放置牵开器期间传导阻滞持续30分钟,在移除牵开器后又持续30分钟。相比之下,在整个实验过程中,悬垂肌瓣技术并未损害肋间神经传导。
我们的实验为开胸术后肋间神经损伤提供了电生理证据。损伤主要归因于肋骨牵开器引起的机械压迫。