BREATH-BY-BREATH NON-INVASIVE CARDIAC OUTPUT MONITOR

我们建议研究和开发逐呼吸、无创的心输出量监测技术。作为一项非常成功的SBIR单芯片实验室气体分析仪计划的结果，低成本的气动转速仪可以补偿密度和粘度的变化，从而可以定期实时测量O2消耗和CO2产生等代谢功能。因此，以前被认为太难或太不切实际的心输出量技术可能是可行的。我们建议重新使用Kim的单次呼吸技术来估计动-静脉二氧化碳含量差异，使用明显更多的肺泡平台上呼出的O2和CO2浓度点来建立Fao_2、Faco_2和呼吸交换率之间的准确关系。Fick方程得出肺毛细血管血流量Qc。由于死腔影响呼出气体和肺泡气体之间的关系，我们提出了一种新的估计方法，该方法基于Fletcher等人(21)的单次呼吸二氧化碳潮气量波形分析，结合虚拟患者迭代的解剖/生理模型，该模型收敛于测量的FeO2和FeCO2。肺分流将通过脉搏血氧仪测定SpO2和根据血液pH模型测定Satvo2和Satco2来解释。来自初步概念验证系统的数据一直令人鼓舞，为活跃的成年人产生了8-10LPM的心输出量，与公布的数据一致。生产设备预计售价1000英镑，重量1磅。建议的商业应用：提供心输出量测量来对目前没有这种监测好处的大量人群进行常规监测，可以显著降低在非心脏相关手术中因未诊断的心脏并发症而导致的巨额后续护理成本和发病率和死亡率。重量轻、坚固耐用的设备非常适合在野外环境中使用，如救护车和MEDEVAC运输，以及医生的办公室、诊所、急诊室和ICU。

We propose to research and develop breath-by-breath, non-invasive cardiac output monitoring technology. As a result of a highly successful SBIR lab- on-a-chip gas analyzer program, low cost pneumotachometers can be compensated for density and viscosity changes so that metabolic functions, such as O2 consumption and CO2 production, can be routinely measured in real time. Thus, cardiac output techniques, previously considered too difficult or too impractical, may be feasible. We propose revisiting Kim's (8) single-breath technique to estimate arterio-venous CO2 content difference, using significantly more exhaled O2 and CO2 concentration points on the alveolar plateau to develop accurate relationships between Fao2, Faco2 and respiratory exchange ratio. The Fick equation yields pulmonary capillary blood flow, Qc. Since deadspace affects the relationship between exhaled and alveolar gasses, we propose a new estimation method based on Fletcher et al's (21) single-breath CO2-tidal-volume waveform analysis combined with a virtual patient iterative anatomical/physiological model that converges on measured Feo2 and Feco2. Pulmonary shunting will be accounted for by determining Spo2 with a pulse oximeter, and Satvo2 and Satco2 from blood pH models. Data from a preliminary proof-of-concept system has been encouraging, yielding cardiac outputs of 8 - 10 lpm for active adults, consistent with published data. Production devices are expected to cost <$1000 and weigh <1 lb. PROPOSED COMMERCIAL APPLICATIONS: The availability of cardiac output measurement to routinely monitor the large population currently without benefit of such monitoring could significantly reduce the huge aftercare costs and morbidity and mortality resulting from undiagnosed cardiac complications in noncardiac-related procedures. A lightweight, rugged device would be ideally suited for use in field environments such as the ambulance and MEDEVAC transport, as well as the doctor's office, clinic, the ER and ICU.