In a recent study entitled “Accuracy of invasive arterial pressure monitoring in cardiovascular patients: an observational study” the authors suggest that when evaluating a patient’s cardiovascular system, a non-invasive blood pressure measurement may be more accurate than the standard invasive method to measure arterial pressure. Improved methods for determining arterial pressure can lead to improved outcomes for people who suffer from pulmonary arterial hypertension, chronic obstructive pulmonary disease, and other diseases affecting the heart. The study was published in the journal Critical Care.
Determining arterial pressure is a standard and important measurement, especially for critically ill patients and patients to be submitted to high-risk surgery since it indicates patient’s cardiovascular system performance. Currently, the standard method relies on an invasive blood pressure (IBP) method, where the arterial pressure is determined by inserting a catheter into an artery. Another method is the non-invasive blood pressure (NIBP) measurement, such as with the oscillometric method, which measures oscillations of blood flow with a sphygmomanometer cuff pressure. This method is expected to be less informative than the invasive method in several conditions (severe hypotension, arterial stiffness and obesity). However, as the IBP method is affected by system calibration errors and may cause overdamping and underdamping, the NIBP may be more accurate in clinical scenarios more prone to these errors.
In this new study, the authors analyzed the incidence of resonance (tendency of a system to oscillate with greater amplitude at some frequencies than at others) and underdamping events in patients submitted to vascular surgery, cardiac surgery or admitted to cardiac surgery intensive care unit. A total of 300 patients were analyzed, and the arterial pressures were measure either by invasive and non-invasive methods. The authors found that approximately 30% of critically ill patients register the occurrence of underdamping/resonance events with an association between catheter diameter and length and underdamping/resonance.
In light of their results, the authors suggest that IBP measurement in some patients can be an inaccurate measurement, and so NIBP may be an additional method to confirm the occurrence of underdamping/resonance events and therefore avoid inappropriate treatments.