Table 2.

Potential sources of error from specific components of the oscillometric method to estimate blood pressure (BP).

Oscillometric component	Potential influence on accuracy
Cuff size	A narrow cuff requires higher pressures to induce maximum pulsations, thus increasing the oscillometric waveform to higher pressures for mean arterial pressure, systolic BP and diastolic BP, but also broadening the oscillometric waveform and increasing pulse pressure [61]
Cuff fit	Compared with a cuff that is placed with a snug fit, the estimation of oscillometric mean arterial pressure increases with the looseness of the cuff fit [68]. In large arms, the shape of the cuff is also important to fit the arm that is conical [69]
Cuff deflation rate	Faster deflation rates are used to reduce BP measurement time but this results in fewer oscillometric waveforms with which to estimate BPs. Missing oscillometric waveform values require different degrees of interpolation relative to deflation rate. Although accuracy may not always be compromised [70], error is expected to increase at faster deflation rates [56, 71]
Extracting the oscillometric waveform	Different filtering methods used to extract waveform pulsations can distort the shape of the extracted pulses and the oscillometric waveform, thus changing BP estimations [72, 73]
Constructing the oscillometric waveform envelope	Several signal processing methods can be used to construct the oscillometric waveform envelope, and this creates variability in waveform envelope morphology as well as different BP estimations [55]
BP algorithms	There is a large variety of algorithms to estimate BP, many of which are patent protected for each individual automated BPMD, and have variable performance characteristics [50, 55] that are difficult to independently scrutinise. Algorithms are empirical and may not account for individual physiological variability in modifying factors such as arterial stiffness [74]. Optimal fixed-ratio coefficients for accurate BP also differ depending on the method used to construct the oscillometric waveform envelope [55]