From the Department of Anaesthesia and Critical Care, University of Wuerzburg, Wuerzburg, Germany.
Anesthesiology. 2018 Nov;129(5):989-999. doi: 10.1097/ALN.0000000000002424.
WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Halothane and caffeine induce excessive sarcoplasmic calcium liberation and skeletal muscle contracture in patients susceptible to malignant hyperthermia (MH) and are utilized for diagnosis in the in vitro contracture test. Intramuscular injection previously caused a marked local lactate increase in MH-susceptible but not in MH-nonsusceptible individuals in vivo. Using shear-wave elastography, this study evaluated localized changes in muscle stiffness after intramuscular injection of halothane and caffeine.
Microdialysis probes were placed into the gracilis muscle of 16 pigs (9 MH-susceptible and 7 MH-nonsusceptible). After local injection of either halothane or caffeine in different concentrations, changes of tissue elasticity surrounding the probe were examined by quantitative shear-wave elastography. Local lactate concentrations were analyzed spectrophotometrically.
Ultrasound elastography detected a temporary increase in local muscle rigidity in MH-susceptible but not in MH-nonsusceptible pigs after 2.5 and 5 vol% halothane and after 10, 40, and 80 mM caffeine, whereas there were no differences in the control groups (median [interquartile range] for maximum effect after 5 vol% halothane: MH-susceptible: 97 [31 to 148] vs. MH-nonsusceptible: 5 [-6 to 18] kPa; P = 0.0006; maximum effect after 80 mM caffeine: 112 [64 to 174] vs. -3 [-6 to 35] kPa; P = 0.0002). These effects were seen rapidly within 5 min. Local lactate concentrations were higher in MH-susceptible versus nonsusceptible pigs after 1 and 2.5 vol% halothane and 10, 40, and 80 mM caffeine (2.5 vol% halothane: MH-susceptible: 2.8 [1.9 to 4.4] vs. MH-nonsusceptible: 0.6 [0.6 to 0.7] mmol/l; P < 0.0001; 80 mM caffeine: 5.2 [4.1 to 6.3] vs. 1.6 [1.2 to 2.4] mmol/l; P < 0.0001). After 10 vol% halothane, rigidity and lactate levels were increased in both MH-susceptible and MH-nonsusceptible animals.
This pilot study revealed shear-wave elastography as a suitable technique for real-time detection of altered tissue elasticity in response to pharmacologic stimulation. By considering the variability of these results, further test protocol optimization is required before elastography could serve as a minimally invasive MH diagnostic test.
本文的新意：背景：氟烷和咖啡因可诱发易患恶性高热（MH）的患者的肌浆网钙离子过度释放和骨骼肌挛缩，并且在体外挛缩试验中用于诊断。肌肉内注射先前在体内导致 MH 易感个体而非 MH 非易感个体的局部乳酸明显增加。本研究使用剪切波弹性成像评估氟烷和咖啡因肌内注射后肌肉僵硬的局部变化。方法：将微透析探针置于 16 头猪（9 头 MH 易感和 7 头 MH 非易感）的骼肌中。在局部注射不同浓度的氟烷或咖啡因后，通过定量剪切波弹性成像检查探针周围组织弹性的变化。通过分光光度法分析局部乳酸浓度。结果：超声弹性成像检测到氟烷 2.5 和 5 容积%以及咖啡因 10、40 和 80mM 后，MH 易感猪而非 MH 非易感猪的局部肌肉僵硬暂时增加，而对照组无差异（氟烷 5 容积%后的最大效应中位数[四分位距]：MH 易感：97[31 至 148]与 MH 非易感：5[-6 至 18]kPa；P=0.0006；咖啡因 80mM 的最大效应：112[64 至 174]与-3[-6 至 35]kPa；P=0.0002）。这些作用在 5 分钟内迅速出现。氟烷 1 和 2.5 容积%以及咖啡因 10、40 和 80mM 后，MH 易感猪的局部乳酸浓度高于非易感猪（氟烷 2.5 容积%：MH 易感：2.8[1.9 至 4.4]与 MH 非易感：0.6[0.6 至 0.7]mmol/L；P<0.0001；咖啡因 80mM：5.2[4.1 至 6.3]与 1.6[1.2 至 2.4]mmol/L；P<0.0001）。氟烷 10 容积%后，MH 易感和 MH 非易感动物的刚性和乳酸水平均增加。结论：本初步研究显示，剪切波弹性成像适合实时检测药物刺激引起的组织弹性变化。考虑到这些结果的可变性，在弹性成像成为一种微创 MH 诊断测试之前，需要进一步优化测试方案。
