Gebien Dov Jordan, Eisenhut Michael
Independent Researcher, Toronto, ON M2K 1G4, Canada.
Luton & Dunstable University Hospital, Lewsey Road, Luton LU4 0DZ, UK.
Diagnostics (Basel). 2024 Oct 18;14(20):2324. doi: 10.3390/diagnostics14202324.
The diaphragm is the primary muscle of respiration. Here, we disclose a fascinating patient's perspective that led, by clinical reasoning alone, to a novel mechanism of spontaneous respiratory arrests termed diaphragm cramp-contracture (DCC). Although the 7-year-old boy survived its paroxysmal nocturnal "bearhug pain apnea" episodes, essentially by breathing out to breathe in, DCC could cause sudden unexpected deaths in children, especially infants. Diaphragm fatigue is central to the DCC hypothesis in SIDS. Most, if not all, SIDS risk factors contribute to it, such as male sex, young infancy, rebreathing, nicotine, overheating and viral infections. A workload surge by a roll to prone position or REM-sleep inactivation of airway dilator or respiratory accessory muscles can trigger pathological diaphragm excitation (e.g., spasms, flutter, cramp). Electromyography studies in preterm infants already show that diaphragm fatigue and sudden temporary failure by transient spasms induce apneas, hypopneas and forced expirations, all leading to hypoxemic episodes. By extension, prolonged spasm as a diaphragm cramp would induce sustained apnea with severe hypoxemia and cardiac arrest if not quickly aborted. This would cause a sudden, rapid, silent death consistent with SIDS. Moreover, a unique airway obstruction could develop where the hypercontracted diaphragm resists terminal inspiratory efforts by the accessory muscles. It would disappear postmortem. SIDS autopsy evidence consistent with DCC includes disrupted myofibers and contraction band necrosis as well as signs of agonal breathing from obstruction. Screening for diaphragm injury from hypoxemia, hyperthermia, viral myositis and excitation include serum CK-MM and skeletal troponin-I. Active excitation could be visualized on ultrasound or fluoroscopy and monitored by respiratory inductive plethysmography or electromyography.
横膈膜是呼吸的主要肌肉。在此，我们揭示了一个引人入胜的患者视角，仅通过临床推理就得出了一种称为横膈膜痉挛 - 挛缩（DCC）的自发性呼吸骤停新机制。尽管这个7岁男孩在夜间阵发性“熊抱痛性呼吸暂停”发作中幸存下来，基本上是通过呼气来吸气，但DCC可能导致儿童，尤其是婴儿突然意外死亡。横膈膜疲劳是婴儿猝死综合征（SIDS）中DCC假说的核心。大多数（如果不是全部）SIDS风险因素都与之相关，如男性、婴儿期早期、呼吸再循环、尼古丁、过热和病毒感染。翻身至俯卧位或快速眼动睡眠期气道扩张肌或呼吸辅助肌失活导致的工作量激增可引发病理性横膈膜兴奋（如痉挛、颤动、抽筋）。对早产儿的肌电图研究已经表明，横膈膜疲劳以及短暂痉挛导致的突然暂时功能衰竭会诱发呼吸暂停、呼吸浅慢和用力呼气，所有这些都会导致低氧血症发作。由此推断，如果不迅速终止，作为横膈膜痉挛的长时间痉挛会诱发持续的呼吸暂停，并伴有严重低氧血症和心脏骤停。这将导致与SIDS一致的突然、迅速、无声死亡。此外，当过度收缩的横膈膜抵抗辅助肌的终末吸气努力时，可能会出现一种独特的气道阻塞。死后这种阻塞会消失。与DCC一致的SIDS尸检证据包括肌纤维中断、收缩带坏死以及阻塞导致的濒死呼吸迹象。从低氧血症、高热、病毒性肌炎和兴奋中筛查横膈膜损伤包括检测血清肌酸激酶-MM和骨骼肌肌钙蛋白-I。活跃的兴奋可以通过超声或荧光透视观察到，并通过呼吸感应体积描记法或肌电图进行监测。
