Noninvasive assessment of arterial pressure

To briefly review recent advances in the noninvasive assessment of arterial pressure (indirect methods) in the field of critical care.

Automated oscillometric measurements underestimate intraarterial systolic blood pressure. Digital photoplethysmography has led to conflicting results, although the obtained respiratory pulse pressure variation correlates with the fluid-challenge-induced changes in stroke volume. The pulse oximetry photoplethysmographic signal recorded at the digital or ear level may be useful in monitoring respiratory arterial pressure variations, although technical improvements and clarifications are needed. Arterial tonometry is increasingly used in the cardiovascular field to reconstruct central aortic pressure. A recent study has shown that radial artery tonometry is feasible in hemodynamically stable patients and that peripheral pulse pressure reflects the combined influences of arterial stiffness and stroke volume, especially in elderly patients. The limitations of this technique include the potential bias related to the use of a generalized transfer function and the difficulty in obtaining reliable recordings in hemodynamically unstable patients.

Intraarterial blood pressure must be preferred over noninvasive blood pressure recordings when critical decisions are required. In hemodynamically stable patients, valuable information may be obtained by using noninvasive techniques, amongst which arterial tonometry seems especially promising.