Focus on: Westchester County Medical Center Division of Biomedical Engineering.

The Division of Biomedical Engineering (DBME), a vital element in the structure of any medical center, provides complete biomedical equipment services at Westchester County Medical Center (WCMC), through a Biomedical Instrumentation Program. Under this program, the DBME assumes direct responsibility for all diagnostic imaging equipment in radiology, radiation medicine and nuclear medicine; and patient care, surgical life support (respiratory care) equipment in critical care units, operating rooms, G.I. (gastro-intestinal) suites, renal center, burn center, emergency rooms, as well as clinical laboratories. In addition, the DBME provides academic and internship programs, research, design, database support, technology planning, and device inspection or evaluation. The DBME is "looking into the future" for a gradual migration of state-of-the-art technology into healthcare.

Computerized long-term trending of respiratory parameters.

This paper presents a program that analyzes data recorded from a Puritan-Bennett 7200a mechanical ventilator. The program generates graphs of major ventilatory parameters, as well as the derivatives of the parameters, such as respiratory rate and minute volume with respect to time. The program also creates a series of reports that summarizes setting changes, alarm violations and resets, and lung mechanics maneuvers during the process of respiratory therapy. These graphs and reports provide clinicians with information, which was not captured for review before, in an organized format allowing them to easily identify trends and, in some cases, events that may affect the patient. The results of a clinical study are also presented. The study was designed to determine the effect of routine patient care on the primary and derived respiratory data so that a correct interpretation of the recorded data could be made. The study showed that the data acquisition program was not sensitive to routine bedside activities, and some significant events, such as patient disconnects, are identifiable in a timely manner and with good accuracy.

Development of a real-time algorithm for predicting sufentanil plasma levels during cardiopulmonary-bypass surgery using a systems approach.

During cardiopulmonary-bypass (CB) procedures, anesthesiologists have traditionally based the administration of narcotics on general dosage recommendations and past experience. Initial doses are usually based on body weight and supplemental amounts are given in anticipation of, or in response to, the effects of surgical stimuli. There has been considerable recent interest in using the population pharmacokinetics of narcotics to optimize the attainment and maintenance of drug plasma concentrations at analgesic target levels which will blunt the hemodynamic responses to noxious stimuli. Moreover, the undershooting or overshooting of the target can be reduced by application of these principles making drug administration more effective and safer. The present study concerns the development of a model for the computer-guided administration of sufentanil throughout surgical procedures involving CB; there is a paucity of studies which have attempted to model the pharmacokinetics of drugs during CB because of the lack of information on the effects of bypass conditions on the pharmacokinetic parameters. We have attempted to approach the effects of hypothermia on sufentanil clearance by applying a continuous temperature correction to the ultimate elimination rate constant (the terminal eigenvalue). This correction is based primarily on the anticipated effects of temperature on the enzyme-catalyzed reactions which are essential for the elimination of drug from the body. An algorithm for the application of the model is also presented.

The changes in brain surface, intracerebral tissue, and transconjunctival oxygen tension during hypo- and hyperventilation.

To evaluate the validity of organ surface oxygen tension monitoring for assessment of cerebral perfusion, the oxygen tension in brain surface (Pbs(O)(2)), intracerebral tissue (Pic(O)(2)), and conjunctiva (Pcj(O)(2)) were measured simultaneously during hypo- and hyperventilation in dogs, and the comparative study was done. Pbs(O)(2) and Pic(O)(2) significantly increased during hypoventilation and decreased during hyperventilation. And the values of Pbs(O)(2) and Pic(O)(2) were correlated to the corresponding Pa(CO)(2) values significantly ( P << 0.001 in each case). On the contrary, Pcj(O)(2) did not change significantly during hypo- and hyperventilation. These findings indicate that Pbs(O)(2) as well as Pic(O)(2) could reflect the changes in cerebral perfusion caused by induced hyper- and hypocapnia but that Pcj(O)(2) could not.

Ventilator risk management using a programmed monitor.

A computer program was written to improve quality control and risk management of patients on ventilators. The software was designed to run on the new-generation Spacelabs PC Monitor interfaced to the Puritan-Bennett 7200a ventilator. Before the program allows connection of the ventilator to a patient, the ventilator is polled for initial hardware status, alarm statuses and alarm limit settings. If there are no hardware failures, alarm violations, or improperly set alarm limits, the program prompts the clinician to connect the ventilator to the patient. Polling is done periodically after patient ventilation begins, and patient data, alarm conditions, or changes to the ventilator settings are automatically written to disk. In addition, real-time data can be displayed at any time during the ventilation session by using a set of touch-screen options. After the ventilation session is complete, the clinician can print the final report in hard copy or to disk.