BREATH-BY-BREATH NON-INVASIVE CARDIAC OUTPUT MONITOR

我们建议研究和开发逐呼吸、无创心输出量监测技术。由于一个非常成功的SBIR实验室-片上气体分析仪程序，低成本的气度计可以补偿密度和粘度的变化，从而可以实时测量代谢功能，如O2消耗和CO2产生。因此，以前认为过于困难或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(8)单呼吸技术来估计动静脉CO2含量差异，使用肺泡平台上更多的呼出O2和CO2浓度点来建立Fao2， Faco2与呼吸交换比之间的准确关系。菲克方程给出了肺毛细血管血流量，Qc。由于死空间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co2 -潮汐-体积波形分析，并结合虚拟患者迭代解剖/生理模型，该模型收敛于测量的Feo2和Feco2。肺动脉分流将通过脉搏血氧仪测定Spo2和血液pH模型中的Satvo2和Satco2来解释。来自初步概念验证系统的数据令人鼓舞，活跃成年人的心输出量为8 - 10 lpm，与已发表的数据一致。预计生产设备的成本小于1000美元，重量小于1磅。建议的商业应用：心输出量测量的可用性，以常规监测大量人口目前没有这种监测的好处，可以显著降低巨大的术后护理成本和发病率和死亡率由未确诊的非心脏相关手术的心脏并发症。该设备重量轻，坚固耐用，非常适合在现场环境中使用，例如救护车和医疗后送直升机运输，以及医生办公室，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.