A comparison of some methods for measuring total respiratory resistance.
A comparison of some methods for measuring total respiratory resistance.
复制标题
一些测量总呼吸阻力的方法的比较。
DOI：
10.1152/jappl.1974.36.1.131
复制
发表时间：
1974
影响因子：
3.3
通讯作者：
C. L. Waltemath
中科院分区：
文献类型：
--
作者：
N. A. Bergman;C. L. Waltemath
METHODSResistance of the total respiratory system (airway, lung tissue, and chest wall) was measured sequentially using three separate methods in anesthetized patients. Recordings obtained were analyzed in five different ways. Anesthetic management varied among the subjects, but all had tightly fitting cuffed endotracheal tubes and, in each subject, spontaneous ventilation was abolished by neuromuscular blockade with clinically used relaxant drugs. All patients were supine and determinations were made during or at the conclusion of surgery. Informed consent for the study was obtained from each subject by an investigator. Anesthesia administered by an anesthesiologist not involved in the study. wasMeasurements were made both with and without an additional external resistor connected to the endotracheal tube. The resistor was a tube (length 40 mm, ID 7.0 mm) made from two endotracheal tube adaptors connected end-to-end. Value of this resistor was determined by measuring pressure drop across it at several measured flow rates. The order in which the different measurement methods were used as well as sequence of inclusion or omission of the additional resis tance was varied among the subjects. The complete sequence of measurements was usual y completed within 5-8 min. Manual artificial ventilation by anesthesia machine was provided between measurements. Pre+ ssure-Jaw-volume method for measurement. Transthoracic pressure and respiratory gas flow rate were measured during artificial ventilation frequencies of approximately 1 S/min and tidal volumes of approximately 500 ml. A piston-in-cylinder ventilator(Harvard Apparatus Co., Inc., Millis, Mass., model 62 1) from which the valves were removed provided a closed system with total rebreathing during the 30-40 s required for measurement. In three subjects the position of the piston in the cylinder was such that one half of the tidal volume was delivered above and one half below FRC. In three other subjects, end-expiratory position was at FRC. Pressure within the airway relative to a tmospheric pressure was measured with a Sanborn 267B pressure transducer which was calibrated with a water manometer. Respiratory gas flow was measured with a pneumotachograph(Fleisch no. 2) and differential pressure transducer(Sanborn 270). The respiratory flow waveform was not demonstrably different from a mathematically derived sine wave. Therefore, the pneumotachograph system could be calibrated from values for respiratory frequency and tidal volume. Both transthoracic pressure and respiratory gas flow were recorded with a Sanborn 964 recording system. Exact respiratory frequency for each subject was determined from these recordings. Exact tidal volume was measured at the conclusion of each study by ventilating a l-liter spirometer. A volume recording was derived by superimposing a strip of flow recording on the flow and pressure records so that points of maximum and minimum volume coincided with their corresponding points of zero flow. Pressureflow-volume recordings so obtained were analyzed in two different ways.
