Diagnostic Performance of Pulse Pressure Variation for Predicting Fluid Responsiveness During Spine Surgery in the Prone Position: A Systematic Review and Meta-Analysis.

BACKGROUND: Pulse pressure variation (PPV) is widely used to guide fluid responsiveness in mechanically ventilated patients, but its accuracy in the prone position remains uncertain. Prone positioning alters respiratory mechanics and venous return, potentially diminishing the respiratory variation in stroke volume that PPV is designed to detect. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of PPV for predicting fluid responsiveness during prone spine surgery. METHODS: We searched MEDLINE, Embase, Scopus, and Cochrane through July 2025 for prospective studies evaluating PPV in adults undergoing prone spine surgery. Two reviewers independently screened studies, extracted data, assessed risk of bias using QUADAS-2, and pooled diagnostic performance using a bivariate random-effects model. The protocol was registered with PROSPERO (CRD420251106134). RESULTS: Of 599 records, 34 underwent full-text review, and 10 studies (433 patients) were included. PPV thresholds ranged from 7% to 15%. Most studies were at low risk of bias except for the index test because thresholds were determined post hoc. For predicting fluid responsiveness, PPV had a pooled sensitivity of 68% (95% CI: 61%-75%) and specificity of 76% (95% CI: 65%-84%), with a summary area under the receiver operating characteristic curve of 0.72 (95% CI: 0.64-0.80). CONCLUSIONS: PPV showed only moderate diagnostic performance for predicting fluid responsiveness during prone spine surgery. Its performance may have been influenced by threshold variability, heterogeneous reference standards, fluid-challenge protocols, ventilation strategies, and positioning systems. PPV should therefore be interpreted alongside complementary dynamic assessments rather than in isolation, particularly during lung-protective ventilation.