Changes in pulse pressure variation induced by passive leg raising test to predict preload responsiveness in mechanically ventilated patients with low tidal volume in ICU: a systematic review and meta-analysis

Pulse pressure variation (PPV) is limited in low tidal volume mechanical ventilation. We conducted this systematic review and meta-analysis to evaluate whether passive leg raising (PLR)-induced changes in PPV can reliably predict preload/fluid responsiveness in mechanically ventilated patients with low tidal volume in the intensive care unit. PubMed, Embase, and Cochrane databases were screened for diagnostic research relevant to the predictability of PPV change after PLR in low-tidal volume mechanically ventilated patients. The QUADAS-2 scale was used to assess the risk of bias of the included studies. In-between study heterogeneity was assessed through the I2 indicator. Publication bias was assessed by the Deeks’ funnel plot asymmetry test. Summary receiving operating characteristic curve (SROC), pooled sensitivity, and specificity were calculated. Five studies with a total of 474 patients were included in this meta-analysis. The SROC of the absolute PPV change resulted in an area under the curve of 0.91 (95% CI 0.88–0.93), with overall pooled sensitivity and specificity of 0.88 (95% CI 0.82–0.91) and 0.83 (95% CI 0.76–0.89), respectively. The diagnostic odds ratio was 35 (95% CI 19–67). The mean and median cutoff values of PLR-induced absolute change in absolute PPV were both -2 points and ranged from -2.5 to -1 points. Overall, there was no significant heterogeneity with I2 = 0%. There was no significant publication bias. Fagan's nomogram showed that with a pre-test probability of 50%, the post-test probability reached 84% and 17% for the positive and negative tests, respectively. PLR-induced change in absolute PPV has good diagnostic performance in predicting preload/fluid responsiveness in ICU patients on mechanical ventilation with low tidal volume. Trial registration PROSPERO (CRD42024496901). Registered on 15 January 2024.