BACKGROUND & AIMS:
:The random-zero and standard mercury sphygmomanometers are used frequently, and sometimes interchangeably, in epidemiologic studies. To determine whether there is a systematic difference between them, the authors measured systolic, fourth-phase, and fifth-phase diastolic blood pressures using both sphygmomanometers simultaneously in a series of six experiments. For most experiments, the system for simultaneous blood pressure measurements employed one cuff connected to both sphygmomanometers, which were carefully calibrated and read by two trained technicians using a double stethoscope. Order of use of the random-zero sphygmomanometer was randomly assigned, and technicians were blind to each others readings. At deflation rates of 2 mmHg/second, readings of the random-zero sphygmomanometer were systematically lower than those of the standard mercury sphygmomanometer: -0.9 mmHg for systolic, -1.8 mmHg for fourth-phase, and -1.8 mmHg for fifth-phase diastolic blood pressures (all differences, p less than 0.001). The difference persisted after adjustment for subject age, sex, heart rate, blood pressure level, observer, and room temperature, and was present for varying deflation rates. However, by draining the residual mercury from a random-zero sphygmomanometer and using the instrument as if it were a standard mercury sphygmomanometer, much of the difference between the two was eliminated. This suggests that the mechanism for the difference relates to the increased height of mercury in the random-zero manometer tube. The authors conclude that the random-zero and standard mercury sphygmomanometers should not be used interchangeably in epidemiologic studies.
背景与目标:
:在流行病学研究中,随机零和标准汞血压计经常使用,有时可互换使用。为了确定它们之间是否存在系统性差异,作者在一系列六个实验中使用两个血压计同时测量了收缩压,第四阶段和第五阶段的舒张压。对于大多数实验,用于同步血压测量的系统都使用一个连接到两个血压计的袖带,并由两名训练有素的技术人员使用双听诊器仔细校准和读取。随机分配零血压血压计的使用顺序是随机的,技术人员对彼此的读数视而不见。在2 mmHg /秒的放气速度下,随机零血压计的读数总体上低于标准汞血压计的读数:收缩压为-0.9 mmHg,第四相为-1.8 mmHg,第五相舒张剂为-1.8 mmHg血压(所有差异,p均小于0.001)。在调整了受试者的年龄,性别,心率,血压水平,观察者和室温之后,这种差异仍然存在,并且存在着不同的放气率。但是,通过从随机零血压计中排出残留的汞,并像使用标准汞血压计一样使用仪器,可以消除两者之间的大部分差异。这表明造成这种差异的机制与零压力表压力管中汞的高度增加有关。作者得出的结论是,在流行病学研究中,不应将零随机汞血压计和标准汞血压计互换使用。