CONTINUOUS MONITORING OF DOPPLER CARDIAC OUTPUT

THE OBJECTIVE OF THIS STUDY IS TO DEVELOP A SYSTEM FOR CONTINUOUSLY MONITORING CARDIAC OUTPUT BY THE USE OF DOP- PLER ULTRASOUND FROM THE ESOPHAGUS. THE PRINCIPLE OF OPERATION IS THAT BLOOD VELOCITY AT THE MEASUREMENT SITE, THE TRANSVERSE AORTA, WILL BE PROPOR- TIONAL TO THE BLOOD FLOW. IT HAS ALREADY BEEN DEMONSTRATED THAT CONTINUOUS WAVE DOPPLER CAN ACCURATELY ASSESS STROKE VOLUME IN MAN. RECENT STUDIES BY OTHERS HAVE SHOWN THAT FLOW VELOCITIES CAN BE DETECTED BY PULSED DOPPLER SENSORS FROM THE ESOPHAGUS. EXPERIMENTS ARE PLANNED TO QUANTIFY THE REQUIREMENTS FOR AN ESOPHAGEAL PROBE DESIGN AND PLACE- MENT TECHNIQUE SO AS TO BE ABLE TO CONTINUOUSLY MONITOR SUCH FLOW. THE GRANTEE HAS SEVERAL SPECIFIC OBJECTIVES: 1) DEVELOP- MENT OF A CONTINUOUS WAVE ESOPHAGEAL TRANSDUCER SYSTEM; 2) TESTING OF THIS SYSTEM IN ANIMALS UNDER CONDITIONS SIMILAR TO CLINICAL SITUATIONS TO VERIFY OPERATION AND REFINEMENT OF PLACEMENT TECHNIQUE; 3) PERFORM ANY NECESSARY REFINE- MENTS OF THE TRANSDUCER AND SYSTEM; AND 4) EVALUATE THE SYSTEM IN 20 HUMAN SUBJECTS IN THE INTENSIVE CARE UNIT AND OPERATING ROOM. THE OBJECTIVE OF THE CLINICAL EVALUATIONS ARE TO REFINE FURTHER THE DESIGN OF THE SYSTEM, TO ASSESS THE FEASIBILITY OF THE TECHNIQUE IN CLINICAL SETTINGS, AND TO PROVIDE THE BASIS FOR A MORE EXTENSIVE EVALUATION TO ASSESS THE EFFICACY OF THE TECHNIQUE AND TO DEVELOP APPLI- CATIONS TO THE PATIENT CARE. AS WELL AS RECOVERY OF NUTRIENTS AND REUSE OF WASTEWATER.