Predicting optimal supraglottic airway device placement: do placement and performance tests measure up?

BACKGROUND

Blind insertion of Supraglottic airway device (SGA) frequently results in suboptimal positioning, with reported incidence rate of 50–80%. Improper placement can lead to perioperative complications such as hypoxia and aspiration. This study evaluates the diagnostic accuracy of five clinical placement and performance tests – oropharyngeal leak pressure (OLP), suprasternal notch test (SNT), bubble test (BT), Ryle’s tube insertion test, and maximum minute ventilation (MMV) – as surrogates for assessing SGA position in the hypopharynx following blind insertion.

METHODS

This single-centre, non-randomised observational study included seventy adult patients (ASA I–III) undergoing elective surgery under general anaesthesia with SGA (Ambu® AuraGain™ or LMA® Supreme™). After induction of anaesthesia, the SGA was inserted with a blind technique. Placement and performance tests were conducted, followed by video laryngoscopic (VL) confirmation of the SGA position. Diagnostic accuracy was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and receiver operating characteristic (ROC) analysis.

RESULTS

Of the seventy patients, 91.4% passed all five tests. All tests demonstrated high specificity (95–100%), with MMV and SNT achieving 100% specificity. Sensitivity for detecting suboptimal placement was low across all tests, with OLP showing the highest sensitivity (28.6%), followed by SNT, BT, MMV (14.3% each), and Ryle’s Tube Insertion (0%). ROC analysis indicated weak predictive ability for all tests (AUC < 0.7). Postoperative complications were minimal, with 37.1% showing blood-stained SGAs and 7.1% reporting minor sore throat.

CONCLUSION

While OLP, SNT, BT and MMV tests exhibit high specificity for confirming optimal SGA positioning, these tests are not reliable screening tools for detecting suboptimal placement. Their high specificity supports their use only as confirmatory adjuncts, not as stand-alone diagnostics. Clinical reliance on these tests may give a false sense of security, especially in the absence of visual confirmation. TRIAL REGISTRATION: The study was registered in ClinicalTrials.gov (ClinicalTrials.gov identifier: NCT03643029) on 20 August 2018.