The vasopressor test (VPT) has been proposed to evaluate changes in tissue perfusion in response to a transient, vasopressor-induced increase in mean arterial blood pressure (MAP). However, the physiological determinants of this response remain unclear. To (1) evaluate capillary refill time (CRT) response to standardized VPT, (2) explore the associations between CRT and splanchnic vascular Doppler indices, and (3) identify baseline hemodynamic predictors of CRT improvement. In this prospective multicenter study, 32 septic shock patients with persistent hypoperfusion and preload unresponsiveness underwent a VPT, increasing MAP from 65 to 85 mmHg. CRT responders were defined as those with a decrease of ≥ 1 s. Visceral Doppler resistive indices were measured to assess regional perfusion. Baseline hemodynamic variables were evaluated as predictors of CRT improvement. Logistic regression and mixed-effects models examined the associations between CRT, stroke volume, and baseline hemodynamics. Eleven patients (34%) showed CRT improvement ≥ 1 s during VPT, whereas 3 (9%) worsened and 18 (57%) had no meaningful change. Changes in CRT were not associated with renal, hepatic, or splenic Doppler resistive indices. Baseline mean systemic filling pressure (Pmsf) was lower in CRT responders (13 10–16 vs. 18 17–21 mmHg, p = 0.0002) and remained independently associated with CRT improvement (β = −0.469, p = 0.035). Mixed-effects models showed an inverse association between Δ stroke volume and ΔCRT (β = −0.043, p = 0.021). Improvement in CRT during VPT identified patients with preserved peripheral perfusion recruitability. Lower baseline Pmsf was consistently associated with CRT responsiveness. The lack of correlation with visceral indices underscores the heterogeneity of regional perfusion responses.
Valenzuela et al. (Wed,) studied this question.