Peripheral intravenous waveform analysis for evaluating volume status in healthy volunteers and mechanically ventilated patients.

Timely diagnosis of blood loss and evaluation of intravascular volume status are pivotal tasks in clinical practice. Recent studies in animals and during lower body negative pressure (LBNP) in humans indicate that peripheral intravenous pressure waveform analysis (PIVA) may detect early stages of blood loss. As PIVA only requires a peripheral venous cannula, it may have value in emergency settings. However, its clinical relevance remains uncertain. This study examined how volume changes affect the PIVA-derived fundamental frequency (PIVAF1). Two cohorts were studied. The LBNP cohort comprised 15 healthy volunteers exposed to simulated blood loss in 10 mmHg increments of LBNP every two minutes from 0 to 80 mmHg, or until hemodynamic decompensation. The general anesthesia (GA)-cohort included 20 patients undergoing laparoscopic surgery who underwent preload increase with a head-down tilt. Peripheral intravenous pressure waveforms were continuously recorded from an antecubital vein and analyzed using short-time Fourier transform to extract the amplitude at the heart-rate frequency (PIVAF1). Changes in PIVAF1 were analyzed using linear regression. In the LBNP-cohort, data were log(e) – transformed and associated with a change per LBNP level of -0.11 (95% CI -0.14 to -0.09, P < 0.001). In the GA-cohort, PIVAF1 did not reliably predict a 10% change in stroke volume with head-down tilt [AUC 0.71 (95% CI 0.47 to 0.96; P = 0.11)]. We found statistically significant reductions in PIVAF1 during simulated blood loss but PIVAF1 did not predict increasing stroke volume during head-down tilt in general anesthesia. The clinical significance of PIVA remains to be elucidated.