Monitoring the anesthetized patient in the operating room.

In general, monitors used by the anesthesiologist in the operating room provide three basic functions: assessment of machine and patient status to ensure safety; assessment of depth of anesthesia; and determination of physiologic variables. Improved monitoring should reduce risk and improve patient care. Some monitoring techniques are used in only a few specialized procedures, particularly in high-risk patients or for prolonged or difficult surgery. However, many less-sophisticated techniques are used in routine daily practice and require similar philosophies of monitoring. The status of the cardiovascular system is assessed primarily by monitoring the electrocardiogram and blood pressure waveforms. Although desired effects of anesthesia impact the central nervous system, this vital organ system is not routinely monitored. Likewise, widespread monitoring of the respiratory system is not routinely accomplished. Monitoring for anesthesia in the operating room has evolved to some extent in response to what can be accomplished rather than what needs to be done. While the potential for an integrated monitoring system--including all patient and delivery system variables--clearly exists, numerous difficulties preclude its becoming a reality. What is required is the development of an integrated system that can augment the anesthesiologist's sixth sense. Initial efforts toward device interface standardization, configurability, and flexibility must be encouraged to pave the way for the integrated, automated anesthesia delivery system of the future.