Schmid B, Grüßer L, Müller L, et al; German Society of Anaesthesiology and Intensive Care (GSAIC) Trials Group. Conventional vs Video-Assisted Laryngoscopy for Perioperative Endotracheal Intubations: A Randomized Clinical Trial.
Prior VL-vs-DL evidence was inconsistent largely because trials were small and didn't separate video laryngoscopy by blade geometry. COVALENT was purpose-built to fix both problems at once.
Video laryngoscopy has increasingly become the perioperative default, but prior evidence directly comparing it with direct laryngoscopy has been mixed, and—critically—most trials pooled Macintosh-shaped and hyperangulated VL blades together despite them being functionally different tools with different learning curves and use cases. COVALENT was designed from the outset (registered 2022) as a three-arm trial specifically to separate these two VL geometries from each other and from DL, in a large enough sample to detect real differences.
| Design | Multicenter (6 sites, Germany & Austria), randomized, 3-arm parallel-group trial |
| Population | 2,532 adults (mean age 59.7, 56.3% male) undergoing surgery under general anesthesia requiring tracheal intubation, Mar 2022–Feb 2025 |
| Arms | Direct laryngoscopy (DL) vs. video laryngoscopy with Macintosh-shaped blade (VLM) vs. video laryngoscopy with hyperangulated blade (VLH) |
| Primary outcome | First-pass intubation success |
| Secondary outcomes | Complications (dental/lip injury, blood on blade), human-factors measures (team communication, task load) |
| Device | First-pass success | Complication rate |
|---|---|---|
| Direct laryngoscopy (DL) | 78.2% | 24.1% |
| Video laryngoscopy, Macintosh blade (VLM) | 82.9% | 23.2% |
| Video laryngoscopy, hyperangulated blade (VLH) | 87.6% | 10.9% |
All pairwise comparisons vs. DL were statistically significant (P<.001). The hyperangulated blade specifically produced roughly half the complication rate of either DL or VLM — not just better first-pass success but a meaningfully cleaner safety profile, consistent with prior hyperangulated-blade data in anticipated difficult airways.
The trial's own supplementary data complicates a simple "video wins, case closed" reading.
Per-site first-pass success with DL ranged from 74% (Bonn) to 88% (Leipzig); VLM ranged from 71% (Salzburg) to 96% (Leipzig). That's a wider spread within a single device across sites than the overall gap between devices. This pattern — along with the trial's overall success rates running noticeably lower than some prior single-center VL studies (e.g., a Cleveland Clinic cohort reporting ~98% first-pass VL success) — suggests local training, staffing mix, and definitions of "attempt" are doing real work here, not just the device itself.
A further counterintuitive finding worth flagging: the clearest first-pass improvement from switching to hyperangulated VL wasn't in the least experienced operators (where you'd expect a device to compensate most for skill gaps) — it was in anesthesiologists with ≥5 years of experience. Independent commentary on this trial (Desmedt & Lascarrou's invited JAMA Netw Open commentary, and independent analysis) both flag that without knowing each experience stratum's actual DL vs. VL success numbers side by side, it's hard to fully separate "VL is intrinsically better" from "this particular cohort's DL skills were comparatively underdeveloped relative to other published DL benchmarks."
The source post's framing holds up well: this is a genuinely well-powered, purpose-built trial answering a question smaller studies couldn't — and it does support hyperangulated VL as the strongest performer on both first-pass success and complication rate, consistent with recent calls to adopt VL as the default. The one caveat worth carrying forward from the supplementary data: the magnitude of the DL-vs-VL gap varied enormously by site, large enough that local training and DL proficiency likely explain part of the effect size — worth keeping in mind before treating "87.6% vs. 78.2%" as a fixed, portable number for your own department's DL-skilled operators.