Bhavani-Shankar K, Moseley H, Kumar A Y, Delph Y
Department of Anaesthesia, Queen Elizabeth Hospital, University of West Indies, Barbados.
Can J Anaesth. 1992 Jul;39(6):617-32. doi: 10.1007/BF03008330.
In the last decade, capnography has developed from a research instrument into a monitoring device considered to be essential during anaesthesia to ensure patient safety. Hence, a comprehensive understanding of capnography has become mandatory for the anaesthetist in charge of patients in the operating room and in the intensive care unit. This review of capnography includes the methods available to determine carbon dioxide in expired air, and an analysis of the physiology of capnograms, which are followed by a description of the applications of capnography in clinical practice. The theoretical backgrounds of the effect of barometric pressure, water vapour, nitrous oxide and other factors introducing errors in the accuracy of CO2 determination by the infra-red technique, currently the most popular method in use, are detailed. Physiological factors leading to changes in end-tidal carbon dioxide are discussed together with the clinical uses of this measurement to assess pulmonary blood flow indirectly, carbon dioxide production and adequacy of alveolar ventilation. The importance of understanding the shape of the capnogram as well as end-tidal carbon dioxide measurements is emphasized and its use in the early diagnosis of adverse events such as circuit disconnections, oesophageal intubation, defective breathing systems and hypoventilation is highlighted. Finally, the precautions required in the use and interpretation of capnography are presented with the caveat that although no instrument will replace the continuous presence of the attentive physician, end-tidal carbon dioxide monitoring can be effective in the early detection of anaesthesia-related intraoperative accidents.
在过去十年中，二氧化碳监测技术已从一种研究工具发展成为一种监测设备，被认为在麻醉期间对确保患者安全至关重要。因此，对于负责手术室和重症监护病房患者的麻醉医生来说，全面了解二氧化碳监测技术已成为必需。本二氧化碳监测技术综述包括测定呼出气体中二氧化碳的可用方法，以及对二氧化碳波形图生理学的分析，随后描述了二氧化碳监测技术在临床实践中的应用。详细阐述了气压、水蒸气、氧化亚氮以及其他因素对目前最常用的红外技术测定二氧化碳准确性产生误差的理论背景。讨论了导致呼气末二氧化碳变化的生理因素，以及该测量值在间接评估肺血流量、二氧化碳产生量和肺泡通气充分性方面的临床应用。强调了理解二氧化碳波形图形状以及呼气末二氧化碳测量值的重要性，并突出了其在早期诊断诸如回路断开、食管插管、呼吸系统故障和通气不足等不良事件中的应用。最后，介绍了使用和解读二氧化碳监测技术所需的注意事项，并提醒尽管没有任何仪器能够取代细心医生的持续在场，但呼气末二氧化碳监测可有效早期发现与麻醉相关的术中事故。
