Pleth variability index may predict preload responsiveness in patients treated with nasal high flow: a physiological...

Area of Science:

• Critical Care Medicine
• Cardiovascular Physiology
• Respiratory Support

Background:

• Assessing fluid responsiveness is crucial for optimizing hemodynamics in critically ill patients.
• Nasal high flow (NHF) therapy is increasingly used, but monitoring fluid status during NHF can be challenging.
• Noninvasive methods for predicting preload responsiveness are needed, especially in patients on NHF.

Purpose of the Study:

• To evaluate the plethysmographic variability index (PVi) as a predictor of preload responsiveness.
• To assess PVi's utility in patients receiving nasal high flow (NHF) therapy (≥30 L/min) with hypoperfusion signs.
• To determine if PVi can guide fluid administration in this specific patient population.

Main Methods:

• Twenty patients on NHF with hypoperfusion signs were enrolled.
• Preload responsiveness was defined as a ≥10% increase in stroke volume (SV) after passive leg raising (PLR).
• SV and PVi were measured using transthoracic echocardiography and PVi monitoring, respectively; reassessed after fluid challenge in responders.

Main Results:

• Sixty percent (12/20) of patients were preload responders.
• Responders exhibited significantly higher baseline PVi (24% vs. 13%) and PVi variation after PLR (ΔPVi) (6.8% vs. -1.7%).
• Baseline PVi (≥16%) and ΔPVi after PLR (≥2%) demonstrated high diagnostic accuracy (AUROC 0.92 and 1.00) for identifying preload responders.

Conclusions:

• The plethysmographic variability index (PVi) shows potential in predicting preload responsiveness in NHF-treated patients.
• PVi measurements, particularly baseline PVi and ΔPVi after PLR, can accurately identify patients likely to benefit from fluid administration.
• This noninvasive index may serve as a valuable tool for clinical decision-making and optimizing fluid resuscitation in critically ill patients on NHF.