Alterations in arterial pressure waveform morphology following volume loading versus vasopressor administration in critically ill patients

Arterial pressure waveform analysis has been used to assess hemodynamic status, however, investigations focusing on waveform morphology remain limited. In this study, we examined changes in selected morphological features of the arterial pressure waveform following volume loading versus vasopressor administration in critically ill patients. In this retrospective observational study, we analyzed adult patients admitted to an intensive care unit between April 2022 and June 2023. Participants were included if they exhibited increased mean arterial pressure (MAP) following either blood return during hemodiafiltration discontinuation (Volume group) or intravenous phenylephrine administration (Pressor group). Arterial waveforms were extracted from one minute before to four minutes after the intervention. We compared 21 waveform-derived features and their normalized parameters at peak MAP with baseline values. Pre- and post-intervention differences for each parameter were assessed using the Wilcoxon matched-pairs signed-rank test. The Volume group comprised 26 patients, and the Pressor group included 20 patients. Systolic angle, systolic dP/dt, and systolic area under the curve (AUC) increased in both groups following intervention. After pulse-pressure normalization, however, systolic AUC increased significantly in the Volume group (median paired difference 4.6 [-0.3-10.2] ms, 95% CI 1.9 to 7.9, P = 0.0038) but not in the Pressor group. This elevation in systolic AUC occurred mainly during the systolic descending phase (4.4 [1.1-9.5] ms, 95% CI 2.7 to 9.1, P = 0.00021). The systolic descending duration exhibited a significant prolongation in the Volume group, whereas no significant change was observed in the Pressor group. Arterial waveform morphology exhibited different patterns of change following blood return versus phenylephrine administration, particularly in the systolic descending phase. Waveform morphology analysis may provide complementary physiological information for monitoring the mechanisms underlying hemodynamic changes.