Mike McEvoy博士，REMT-P，RN，CCRN
EMS providers often measure blood pressure (BP) in difficult situations that pose tremendous chances for error. Let’s review the most likely sources of error in blood pressure measurement and discuss some tips for obtaining blood pressures in tough conditions.
Actual measurement of blood pressure requires placement of a monitor directly into an artery. Short of this, the best that can be done is to measure blood flow. Typically, pressure and flow are related, except in shock states when flow is reduced and pressure rises from increased vascular tone. In the prehospital environment, what we call blood pressure measurement is actually measuring blood flow.
测量血压的最常见错误是使用错误的袖口。一个太大的BP袖口会产生错误的低读数，而过于小的袖带将提供虚假读数的读数。适当尺寸的BP袖口的最实用方法是挑选袖口，该袖带覆盖患者的肘部和肩膀之间的三分之二。携带至少三个袖带尺寸（大型成人，常规成年和小儿）将适合大多数成年人口。如果您经常治疗小儿患者，则需要多个较小的尺寸。
The second most common error in BP measurement is incorrect limb position. To accurately assess blood flow in an extremity, influences of gravity must be eliminated. To do this, the arm (or leg) where the cuff is applied must be at mid-heart level. An extremity above heart level will provide a falsely low BP whereas false high readings will be obtained from limbs located below heart level. Seated upright and supine patients pose little difficulty as long as the extremity in which the pressure is taken remains at the patient’s side. Side-lying or other oddly positioned patients pose problems for accurate pressure measurement. To correctly assess BP in a side-lying patient, hold the BP cuff extremity at mid-heart level while taking the pressure.
在某些情况下，根本无法进行BP测量。我们可以通过评估患者的脉冲来粗略估计收缩BP（SBP）。径向脉冲的存在通常需要至少80 mmHg的SBP。股骨脉冲需要至少70个SBP，并且可触及的颈动脉脉冲需要超过60的SBP。
Noise is a factor that can also interfere with BP measurement. Many ALS units carry doppler units that measure blood flow with ultrasound waves. Doppler units amplify sound and are useful in high noise environments. Obtaining SBP using palpation of a distal pulse while deflating the blood pressure cuff is generally accurate to within 10 to 20 mmHg of an auscultated reading. Oximeter waveforms are also useful in measuring return of blood flow during BP cuff deflation and are as accurate as pressures obtained by palpation.
服装，患者进入和袖口尺寸是经常干扰常规BP测量的障碍。考虑使用替代部位，例如在听诊或触诊径向动脉的同时将BP袖带放在患者的下臂上方。大腿或下腿可以以类似的方式使用（与袖口远端的脉搏点结合使用）。所有这些位置通常用于监测医院环境中的BP，通常提供与上臂传统测量相当的结果。
Electronic blood pressure units, also called Non Invasive Blood Pressure (NIBP) machines, sense air pressure changes in the cuff caused by blood flowing through the BP cuff extremity. Sensors estimate the Mean Arterial Pressure (MAP) and the patient’s pulse rate. Software in the machine uses these two values to calculate the systolic and diastolic BP. To ensure accuracy from electronic units, it is important to verify the displayed pulse with an actual patient pulse. Differences of more than 10% will seriously alter the unit’s calculations and produce incorrect systolic and diastolic values on the display screen.
Mike McEvoy博士，RN，CCRN，REMT-P，是纽约Saratoga县的EMS协调员。他是前法医心理学家，现在在奥尔巴尼医学中心的心脏外科ICU工作，并在纽约的奥尔巴尼医学院任教。他是克利夫顿公园半岛救护车队的护理人员，也是西新春消防局的医疗顾问。他目前担任纽约州EMS理事会和州紧急医疗咨询委员会的成员，并担任纽约州消防局长协会EMS部门的主席。
