Gastric tube placement through the drainage channel of second-generation supraglottic airway devices: a systematic review with evidence mapping

Background Second-generation supraglottic airway (SGA) devices incorporate a dedicated gastric drainage channel that permits placement of a gastric tube (GT), but whether GT placement should be used routinely during general anaesthesia remains uncertain. We conducted a systematic review with evidence mapping to characterize the available evidence and its clinical interpretation across scenarios. Methods MEDLINE, Embase, CENTRAL, Web of Science, and Scopus were searched from inception to 18 April 2026 (PROSPERO: CRD420261368854). A prespecified three-tier framework separated direct comparative studies of GT placement versus non-placement (Tier 1) from indirect clinical evidence (Tier 2) and complementary mechanistic or practice-based evidence (Tier 3). Risk of bias was appraised using design-appropriate tools, and GRADE was applied to five prespecified clinical outcomes. Narrative synthesis followed SWiM guidance, and an interpretive scenario-based framework was derived from the synthesis. Results Thirty-six studies were included: 2 Tier 1, 33 Tier 2, and 1 Tier 3 study. Across the 35 clinical studies, 4,469 adults contributed data. Tier 1 evidence was limited: Hell et al. reported gastric insufflation in 10.9% of patients with a GT versus 2.7% without ( P = 0.009), whereas Freisburger and Goldmann found no material change in oropharyngeal leak pressure with a GT in situ ( P = 0.6). Tier 2 evidence did not identify a clear signal of clinically important gastric insufflation, regurgitation, or pulmonary aspiration attributable to GT placement, but outcome definitions and detection methods were heterogeneous. GRADE certainty was Low for gastric insufflation and oropharyngeal leak pressure and Very low for regurgitation, pulmonary aspiration, and postoperative nausea and vomiting. Clinical scenarios were grouped into three interpretive categories reflecting indirect evidence signals consistent with GT placement, no evidence supporting routine GT placement, or insufficient or context-limited evidence. Conclusion Current evidence is most consistent with a scenario-dependent interpretation of GT placement through the drainage channel of second-generation SGAs, rather than routine universal placement or universal avoidance; the available sample sizes were insufficient to exclude clinically important differences in rare safety outcomes. Direct GT-strategy trials are needed in underrepresented scenarios. Systematic Review Registration https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=1368854 , identifier CRD420261368854.