Interpretation of beat-to-beat blood pressure values in the presence of ventilatory changes.

When blood pressure is measured invasively in the operating room or intensive care unit, it is reasonable to expect useful systolic, diastolic, and mean pressure values to be displayed at all times. If blood pressure is stable from beat to beat, display of values from any beat will suffice. However, the pressure often fluctuates from beat to beat. Display of values from every beat would yield a confusing jumble of numbers. This article describes an algorithm for selecting values that appear physiological useful from blood pressure waveforms that vary with ventilation. Two classes of variation are discussed. The algorithm is optimized from the type of variation seen in pulmonary artery pressure waveforms.