Accuracy of the Takeda TM2420 ambulatory blood pressure monitor

1. The accuracy of blood pressure measurement with the Takeda TM‐2420 ambulatory blood pressure monitor and the TM‐2020 data recorder have been assessed by comparison with simultaneous measurements taken using auscultation and direct femoral artery measurements. 2. Systolic blood pressure was underestimated by the TM‐2420 by a mean of 10 mmHg (s.d. = 6, 95% confidence interval (CI) =−13 to −7) over the range of pressures measured by auscultation. It was underestimated by 23 mmHg (s.d. = 12, 95% CI =−28 to −18) compared with direct femoral artery measurements. 3. Diastolic pressure measurements were similar to those obtained by auscultation. When compared with direct femoral artery recordings, diastolic pressure was overestimated by about 5 mmHg (s.d. = 4, 95% CI = 3.4–6.6), which is consistent with indirect readings, taken with a ‘standard’ cuff (inflatable bladder 23 cm × 12 cm). 4. The TM‐2420/2020 is thus suitable for ambulatory measurements of blood pressure when diastolic pressure is the criterion of interest.