Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Continuous cardiac output and left atrial pressure monitoring by pulmonary artery pressure waveform analysis.
We introduce a novel technique for continuous (i.e., automatic) monitoring of cardiac output (CO) and left atrial pressure (LAP) by mathematical analysis of a pulmonary artery pressure (PAP) waveform. To obtain an initial evaluation of the technique, we applied it to PAP waveforms obtained from nine critically ill patients and compared the resulting CO and LAP estimates with standard operator-dependent thermodilution and pulmonary capillary wedge pressure measurements, respectively. We report that the technique achieved an overall CO error of 17.2% and an overall LAP error of 15.8%. With further testing, the technique may ultimately be employed so as to permit, for the first time, continuous CO and LAP monitoring in critically ill patients.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Evaluation of external cardiac massage performance during hypogravity simulation.
Preservation of astronaut crew health during an exploration mission to the Moon or Mars will be crucial to mission success. The likelyhood of a life threatening medical condition occurring during a mission to Mars has been estimated by NASA to be 1% per year. Since basic life support is a vital skill in critical care medicine, plans must be in place for cardiopulmonary resuscitation in both microgravity and hypogravity (i.e. on the surface of the Moon or Mars). ⋯ Elbow flexion was measured using an electrogoniometer in order to assess the use of arm muscles to achieve chest compressions. This study found that depth (Lunar and Mars) and rate (Mars) of chest compression was below American Heart Association recommendations during hypogravity simulation in the female group. Furthermore, elbow flexion proved to be significantly greater during Lunar and Mars hypogravity simulation than that of the 1G control condition, suggesting that upper arm force may be used to counter the loss of body weight in an attempt to maintain adequate chest compression under these conditions.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Transpulmonary dilution system identification for pulmonary blood volume measurements by contrast echocardiography.
Pulmonary blood volume (PBV) is an important parameter to assess the condition of the lungs and the transpulmonary circulation. Unfortunately, its measurement is limited by the need for central catheterization. Contrast ultrasonography allows overcoming this problem. ⋯ Volume measurements show accurate in-vitro results with a correlation coefficient higher than 0.99. The clinical feasibility is confirmed by 70 measurements in patients. Beyond an accurate quantification of pulmonary blood volume, the proposed method also permits the characterization of the transpulmonary hemodynamics, possibly adding novel diagnostic value to the measurement.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Circuit compliance compensation in lung protective ventilation.
Lung protective ventilation utilizes low tidal volumes to ventilate patients with severe lung pathologies. The compensation of breathing circuit effects, i.e. those induced by compressible volume of the circuit, results particularly critical in the calculation of the actual tidal volume delivered to patient's respiratory system which in turns is responsible of the level of permissive hypercapnia. ⋯ Experimental tests conducted in-vitro show that the actual tidal volume can be reliably estimated if the compliance of the breathing circuit is measured with the same parameters and ventilation technique that will be utilized in lung protective ventilation. Differences between volume and pressure controlled ventilation are also quantitatively assessed showing that pressure controlled ventilation allows a more reliable compensation of breathing circuit compressible volume.
-
Conf Proc IEEE Eng Med Biol Soc · Jan 2006
Observer design in switching control of neuromuscular blockade: clinical cases.
This paper concerns the application of multiple model switched methods to the control of neuromuscular blockade of patients undergoing anaesthesia. Since the model representing the neuromuscular blockade process is subject to a high level of uncertainty due both to inter-patient variability and time variations, switched methods provide the adaptation capability needed to achieve the desired performance. ⋯ Guidelines are provided for adequate selection of the characteristic polynomial defining the observer error dynamics. Second, clinical results using atracurium as blocking agent are reported in order to illustrate the use of the proposed control structure in actual clinical practice.