Respiratory monitoring provides a better physiologic understanding of the critically ill patient. Arterial blood gas analysis is a commonly used invasive technique to assess gas exchange and acid base status. However, with the development of noninvasive methods to assess gas exchange, pulse oximetry and capnography have become more popular. Research has also focused on other invasive techniques that assess the degree of tissue hypoxia. Monitoring respiratory neuromuscular function is rarely done at the bedside, but advances in technology enable the measurement of respiratory drive by analyzing breathing patterns. Assessing respiratory muscle function at the bedside is accomplished by measuring respiratory pressures with voluntary maneuvers or stimulation of the phrenic nerve. These measurements provide information on respiratory muscle performance and may predict success or failure after discontinuation of mechanical ventilation. Other tests of pulmonary function in the critically ill patient include compliance and vital capacity measurements and the generation of flow-volume and pressure profile curves. In addition, the ability to measure autopositive end-expiratory pressure provides valuable information on respiratory system mechanics. Most importantly, a complete physical examination coupled with the use of respiratory monitoring equipment greatly enhances the predictive power of all monitoring systems. In this way, a better understanding of the pathophysiology of a patient's disease will be gained.
展开▼
