12/14/2023 0 Comments Physiologic dead space calculation![]() By the 1970s, exhaled CO 2 was monitored in ICUs using mass spectrometry systems that aspirated exhaled gas through long lengths of capillary tubing to a central monitoring location. The collected CO 2 in each bag was then analyzed multiple times to yield the average CO 2, which was plotted over time, thus resulting in the first exhaled capnogram. 2 This process entailed capturing exhaled gas using a system the size of a telephone booth consisting of a series of electro-mechanically controlled valves, which directed sequential portions of expired air into 6 small rubber bags. A decade later, a technique was developed to analyze exhaled CO 2 from a single breath during vigorous exercise. ![]() The volume of absorbed CO 2 was then compared with the total gas volume, which yielded the fraction or percentage of CO 2 present. 1 This process of analysis was painstakingly tedious, using an intricate apparatus that involved measuring quantities of CO 2 and other gases that were chemically absorbed from a known gas volume. Some apparatus dead space may actually reduce total dead space, as an ETT bypasses the majority of anatomical dead space of the patient (nasopharynx).ĭead space from the patient.The measurement of CO 2 in air was first developed around 1918 and performed to analyze gas concentrations in mines. ![]() ![]() Types of Dead Spaceĭead space from equipment, such as tubes ventilator circuitry. Glomerular Filtration and Tubular Functionĭead space is the proportion of minute ventilation which does not participate in gas exchange. Functional Anatomy and Control of Blood Flow ![]()
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