Apparently less value of blood pressure among healthy people: is the cuff width responsible?

Blood pressure in normal adults in the present study population in Nepal is found to be less in comparison to that recorded in Framingham study, USA. To find out the cause of variation of blood pressure values, this study was designed. Blood pressures of healthy young subjects were recorded by mercury sphygmomanometer having standard Riva-Rocci cuff. The mid-arm-circumference of the same subjects were measured by a measuring tape. Blood pressure for male and female subjects was found to be 115/77 mmHg and 107/73 mmHg respectively. Mid-arm-circumferences of male and female volunteers were recorded approximately 25 cm and 23 cm respectively. As per rule, width of the cuff should be 40% of the mid-arm-circumference. Nevertheless, the calculated value of 40% of the mid-arm-circumference was found to be less than 12 cm. The calculated value of 40% of mid-arm-circumference for male and female volunteers was found to be approximately 10 cm and 9 cm respectively in this study population. So, the width of the cuff is relatively more than what it should be, for this study population. This may be the cause of less value of blood pressure in normotensive population in this study. Cuff size should be considered carefully to avoid misinterpretation of borderline hypertensives as normotensives.