Predictive ability of pulse oximetry-derived indices for hypotension after spinal anaesthesia for caesarean section: protocol for a systematic review and meta-analysis

INTRODUCTION: In general, caesarean sections are performed under spinal anaesthesia. Hypotension after spinal anaesthesia adversely affects both the mother and fetus. Although several studies have used pulse oximetry-derived indices, such as pulse perfusion index (PI) and Pleth variability index (PVI), to predict hypotension after spinal anaesthesia, the predictive ability of the PI and PVI remain controversial. METHODS AND ANALYSIS: We prepared this protocol following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols guidelines. We will conduct searches of MEDLINE, Embase, Web of Science, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Clinicaltrial.gov, European Union Clinical Trials Register (EU-CTR), WHO International Clinical Trials Registry Platform (ICTRP) and University Hospital Medical Information Network Clinical Trials Registry (UMIN) from inception until 8 October 2022. We will include retrospective and prospective observational studies and randomised controlled trials that evaluated the predictive ability of PI and PVI for hypotension after spinal anaesthesia for caesarean section, published in any language. We will exclude case reports, case series and animal studies. Two authors will independently scan and select eligible studies and perform data extraction and assessment of risk of bias. We will estimate predictive ability of PI and PVI as indices of hypotension after spinal anaesthesia for caesarean section using the Reitsma-type bivariate random-effects synthesis model and the hierarchical summary receiver operating characteristic curve. We will assess the quality of evidence using the Grading of Recommendation Assessment, Development and Evaluation approach. ETHICS AND DISSEMINATION: Ethics approval is not required as the systematic review will use existing published data. The results will be submitted for publication in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: CRD42022362596.