Development of an Active Controlled Stretcher for an Ambulance

近年来，在日本，大量的关注已经支付给病人的死亡在救护车运输到达医院之前，所谓的DOA（到达时死亡）。我们认为，在救护车运输过程中，患者病情恶化的一个因素是救护车与私家车相比，其特征在于：振动，加速和减速。为了解决这一问题，人们对担架的隔振设计进行了大量的研究，但发现担架上的人体在制动时会产生脚-头加速度的变化。当救护车行驶在曲折或狭窄的道路上，反复进行加速或减速时，血压变化（BPV）尤为明显。由于血压的强制性变化可能导致患者病情恶化，因此有必要使用担架来减少脚到头加速度的影响，并降低运输过程中的BPV。因此，我们工作的救护车担架的设计，从一个稍微不同的角度，因为没有这样的研究已经做了设计的担架，减少BPV。在1994年，我们调查了效果的主动控制担架（ACS）的BPV减少模拟分析。仿真结果表明，ACS可以有效地降低BPV，舒适地运送病人。1995年，我们为一辆救护车设计了一种用于降低病人血压波动的自动控制系统，并利用该系统进行了紧急制动试验，结果表明，自动控制系统可以根据救护车行驶前后的加速度连续控制担架在重力作用下的倾斜角度，从而有效地降低脚-头加速度。

Recently in Japan, a great deal of attention have been paid to the patient's death during ambulance transport before arriving at hospital, called DOA (Dead On Arrival). We consider that a deteriorating factor of the patient's condition during ambulance transport is a relatively poor ride of the ambulance compared with a private car characterized by : vibration, acceleration, and deceleration. To solve the problem, many researches have been made on the design of the stretcher based on the isolation of the ambulance vibration.We have, however, found that the blood pressure of human laying on a stretcher varies during a brake causing foot-to-head acceleration. The blood pressure variation (BPV) especially appears when the ambulance runs through a zigzag or narrow road ; the accelerations or decelerations are repeatedly performed. As the enforced change of the blood pressure may lead to deterioration of patient's condition, it is necessary to use a stretcher to decrease the effect of the foot-to-head acceleration and to reduce the BPV during transport. We have, therefore, worked on the design of the ambulance stretcher from a slightly defferent angle, since no such studies have been done on designing of a stretcher which reduces the BPV.In 1994, we investigated the effect of an actively controlled stretcher (ACS) on the reduction of the BPV by simulation analysis. The simulation results suggest that the ACS can effectively decrease the BPV and comfortably transport the patient. In 1995, we designed an ACS for an ambulance to reduce patient's blood pressure variation, and performed emergency brake tests using the ACS.The experimental results showed that the ACS can effectively decrease the foot-to-head acceleration by continuously controlling the tilying angle of the stretcher under gravity according to back-to-front acceleration of the running ambulance.