Tatman Lauren M, Upchurch Weston J, Scholz Natalie, Wagstrom Emily, Smith Lauren L, Bechtold Joan E, Schmidt Andrew H, Iaizzo Paul A
Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN. Dr. Tatman is now with the Department of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN.
Department of Surgery, University of Minnesota, Minneapolis, MN; and.
J Orthop Trauma. 2020 Oct;34(10):518-523. doi: 10.1097/BOT.0000000000001799.
To identify potential physiologic markers of muscle ischemia to serve as diagnostic indicators of compartment syndrome. We hypothesize that muscle bundles in hypoxic conditions will elicit decreases in potential hydrogen (pH) and increases in lactate and potassium that correlates with decreased muscle twitch forces.
We performed an ex vivo evaluation of individual skeletal muscle bundles obtained from a swine's diaphragm that were exposed to hypoxic conditions and compared with control groups. Over a 4-hour period, we evaluated the following parameters for each muscle bundle: muscle twitch forces and levels of potassium, lactate, and pH. Comparisons between the hypoxic and control groups were calculated at each time point using the 2-tailed Wilcoxon rank sum test for nonparametric data. Longitudinal associations between biomarkers and muscle twitch forces were tested using repeated measures analyses.
The hypoxic group elicited more significant decreases in normalized muscle twitch forces than the control group at all time points (0.15 g vs. 0.55 g at 4 hours, P < 0.001). Repeated measures analyses of the hypoxic group demonstrated a statistically significant association between potassium, lactate, and normalized peak force over the course of time. Potassium demonstrated the strongest association with a 1 mmol/L unit increase in potassium associated with a 2.9 g decrease in normalized peak force (95% confidence interval -3.3 to -2.4, P < 0.001). The pH of all muscle baths increased over the course of time at similar rates between the study groups.
This study used an ex vivo ischemic skeletal muscle model as a representation for pathophysiologic pathways associated with compartment syndrome. In this experimental approach we were unable to evaluate the pH of the muscle bundles due to continuous applied gassing. Our findings support further evaluations of potassium and lactate levels as potential diagnostic markers.
识别肌肉缺血的潜在生理标志物，以作为骨筋膜室综合征的诊断指标。我们假设，缺氧条件下的肌束会导致潜在氢离子（pH）降低、乳酸和钾增加，且这些变化与肌肉抽搐力降低相关。
我们对从猪膈肌获取的单个骨骼肌束进行了体外评估，使其暴露于缺氧条件下，并与对照组进行比较。在4小时内，我们评估了每个肌束的以下参数：肌肉抽搐力以及钾、乳酸和pH水平。使用双尾Wilcoxon秩和检验对非参数数据在每个时间点计算缺氧组和对照组之间的差异。使用重复测量分析测试生物标志物与肌肉抽搐力之间的纵向关联。
在所有时间点，缺氧组的标准化肌肉抽搐力下降比对照组更显著（4小时时分别为0.15克和0.55克，P < 0.001）。对缺氧组的重复测量分析表明，在整个过程中，钾、乳酸与标准化峰值力之间存在统计学上的显著关联。钾表现出最强的关联，钾每增加1 mmol/L单位，标准化峰值力下降2.9克（95%置信区间 -3.3至-2.4，P < 0.001）。在研究组之间，所有肌肉浴的pH在整个过程中以相似的速率增加。
本研究使用体外缺血骨骼肌模型来代表与骨筋膜室综合征相关的病理生理途径。在这种实验方法中，由于持续通气，我们无法评估肌束的pH。我们的研究结果支持进一步评估钾和乳酸水平作为潜在的诊断标志物。
