Systolic pressure variation and pulse pressure variation

Respiratory variations in arterial pressure during positive pressure mechanical ventilation. SPV is a direct measurement of the difference between the highest systolic blood pressure (SBP_MAX) and lowest systolic blood pressure (SBP_MIN) values occurring over a respiratory cycle and is reported in mmHg. In contrast, PPV is reported as a percentage using the following formula: PPV = 100 x (PP_MAX – PP_MIN/PP_MEAN), where PP_MEAN = (PP_MAX + PP_MIN)/2. To account for slight variations between respiratory cycles, both SPV and PPV are usually measured over three or more breaths, and an average value is then reported.