ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The application of a medical mass spectrometer for the monitoring of respired gases in the respiratory intensive care unit of a community hospital is reviewed. This monitoring system is routinely used with intubated patients for periodic monitoring of end-tidal co2tensions (PETCO2), FIO2, and PETO2dead space to tidal volume ratios, and the determination of AaDO2; the value of these measurements is discussed. It is especially useful for continuous monitoring at critical points in the patient's course such as weaning from the ventilator, determining optimal ventilator settings, monitoring unstable nonintubated patients, and in better defining the pathophysiological disturbances impeding patient progress, examples of which are presented. Preliminary observations suggest it may also provide a simple technique for determining optimal expiratory retard settings. The initial cost of such a system is justified by the benefit to the patient, i.e., reduction in the frequency of nonessential arterial blood gas determinations, shortened weaning period, and early detection of potentially dangerous trends. Technical problems encountered with this system and potential future uses are also discussed.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

This paper outlines a computerized system for monitoring physiological functions during exercise, using a mass spectrometer for analyzing the concentration of the mixed expired air. Examples are provided illustrating the operation of this system in both research and clinical situations. The most remarkable aspect of the system is its versatility, coupled with its accuracy. While the applications reviewed in this paper are rather narrow, work has been initiated using the mass spectrometer to measure residual lung volumes by the oxygen dilution technique, cardiac output by the CO2rebreathing technique, and total body density by the helium dilution technique. The application of the mass spectrometer into other areas most certainly will occur in the near future.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The medical mass spectrometry as a monitoring instrument in a respiratory intensive care unit (RICU) is described. Its uses, both routine and as a tool for innovative techniques in respiratory care, are many. As an adjunct to traditional and intermittent mandatory ventilation (IMV) weaning techniques, monitoring of expired respiratory gases can hasten the safe removal of patients from mechanical ventilators. A specialized technique of dealing with ventilating the lungs differentially when their mechanical properties differ is described to illustrate the versatility of the instrument. In critical care areas, monitoring of patients with respiratory problems should include continuous monitoring of end-tidal or expired CO2.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The mass spectrometer is a well established tool for the measurement of the partial pressures of gases in respiratory gas mixtures and in flowing blood. Only recently has mass spectrometry been applied to the measurement of gas tensions in tissue. Both blood and tissue gas tension measurements by mass spectrometry were made possible by the development of a special sampling catheter surrounded at its tip by a gas—but not liquid—permeable membrane. The partial pressure of each gas at the external surface of the membrane determines the flow of that gas across the membrane which, in turn, is measured by the mass spectrometer. The use of a Teflon membrane permits tissue measurements because its low permeability to gases reduces the sampling rate of gas molecules with the result that the depletion of gas molecules in the tissue surrounding the membrane is minimal. Mass spectrometry is the only technique whereby it is possible to measure regional tissue pO2and pCO2and other gas tensions simultaneously and continuously. One application of mass spectrometric tissue gas tension measurements is the monitoring of myocardial ischemia through measurements of myocardial tissue pO2and pCO2. We have reviewed the work of others and ourselves in this field.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Since 1971, we have used a mass spectrometer system for automatic hourly sampling of airway gases on a 24-hour basis in our 12 bed Critical Care Unit. Used in conjunction with arterial and mixed-venous blood samples, the availability of end-tidal O2and CO2values allows early identification of increasing AaDO2and aADCO2gradients. The ability to monitor end-tidal CO2allows the monitoring of the adequacy of alveolar ventilation both in patients on and following removal from mechanical ventilation. Continuous information of the end-tidal PCO2is of particular value in the management of patients with severe head injury.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The availability of a rapidly responding arterial catheter and gas analyzer permits the observation of inert gas washout from arterial and alveolar sources. These curves are a logical development of alveolar washout techniques and appear to provide significant new information. While a detailed and formal mathematical treatment of combined alveolar, arterial, and mixed venous washout curves has not yet been derived, inspection and measurement of the y-intercept of the terminal slow space has provided considerable understanding into the distribution of V/Q ratios in the critically ill patient.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Circulatory, respiratory, and metabolic variables were measured with a mobile clinical bedside unit in 41 patients during the first 48 hours after open heart surgery. Calculations were carried out off-line by a computer program. The variables were measured during controlled mechanical ventilation and compared with those obtained during spontaneous breathing and after resumption of mechanical ventilation; attempts at spontaneous breathing were categorized as successful or unsuccessful. The variables were compared before, during, and after the successful and the unsuccessful attempts at spontaneous breathing.In the series as a whole, the onset of spontaneous breathing was characterized by increases in cardiac output, radial arterial and pulmonary arterial pressures, and mixed venous oxygen tension (Pvo2) and content (Cvo2), as well as diminished arterial and mixed venous oxygen content differences (avDO2); no significant changes in oxygen consumption (Vo2) were seen.Unsuccessful attempts disturbed the patient's physiological equilibrium by reducing oxygen delivery and not increasing Vo2, while increasing ventilatory work. In general, resumption of controlled ventilation restored the physiological variables to their control conditions. Successful attempts at spontaneous breathing did not greatly affect the physiological variables. The indication for resumption of controlled ventilation after periods of spontaneous breathing is the combination of increased ventilatory work with diminished circulatory and respiratory functions.

ISSN:0090-3493    

出版商:OVID    

年代:1976

数据来源: OVID