Clark C H, Gutierrez G
Pulmonary and Critical Care Medicine Division, University of Texas Medical School, Houston.
Am J Crit Care. 1992 Sep;1(2):53-60.
Monitoring the adequacy of tissue oxygenation is an important goal in the care of the critically ill patient. Global alterations in tissue oxygenation are inferred from changes in systemic oxygen transport (defined as the product of cardiac output and arterial oxygen content) and total oxygen consumption. These parameters, however, cannot measure the level of oxygenation of specific tissue beds, in particular those that are first affected by hypoxia, such as the gastrointestinal tract and the kidneys.
Gastrointestinal tonometry is a new method for measuring the partial pressure of carbon dioxide of the gastrointestinal mucosa. This information can be used in conjunction with the arterial blood bicarbonate to calculate the pH of the mucosa. Mucosal acidosis correlates well with the onset of anaerobic metabolism in response to hypoxia or sepsis. This review discusses the basic principles of tonometry, the results of experimental and clinical studies, and the practical aspects related to the implementation and use of tonometers in patients in the critical care unit.
Gastrointestinal tonometry is a relatively noninvasive device that appears capable of measuring metabolic changes produced by hypoxia. Because of the sensitive nature of the gastrointestinal mucosa, these changes often occur well in advance of other, more common, indices of hypoxia. The use of the tonometer may become a routine procedure in the overall monitoring of critically ill patients.
监测组织氧合是否充足是重症患者护理的一个重要目标。组织氧合的整体变化可通过全身氧输送（定义为心输出量与动脉血氧含量的乘积）和总氧消耗的变化来推断。然而，这些参数无法测量特定组织床的氧合水平，尤其是那些首先受到缺氧影响的组织床，如胃肠道和肾脏。
胃肠张力测定法是一种测量胃肠黏膜二氧化碳分压的新方法。该信息可与动脉血碳酸氢盐结合使用以计算黏膜的pH值。黏膜酸中毒与缺氧或脓毒症时无氧代谢的发生密切相关。本综述讨论了张力测定法的基本原理、实验和临床研究结果以及与重症监护病房患者使用张力计相关的实际问题。
胃肠张力测定法是一种相对无创的设备，似乎能够测量由缺氧产生的代谢变化。由于胃肠黏膜的敏感性，这些变化通常比其他更常见的缺氧指标提前出现。张力计的使用可能会成为重症患者整体监测中的常规程序。
