Ramped vs Supine Preoxygenation

Interesting paper here, retrospective data pulled from the NEAR registry, a big high quality airway registry.

The take home point was NO difference in desaturations during induction in the ramp vs supine position. They reported DL and VL cohorts separately. Now I like to ramp patients, especially those with low GCS or obesity. So I am going to find the issues with the paper, and try to hold strong in my beliefs.

But seriously, there are some problems. It is retrospective. The patients who were ramped were probably sicker and more obese! It turns out they are:

However, obesity and subjective impression of difficult airway were more common in the ramped cohorts (Table 1) and independently associated with postinduction hypoxemia (Tables 3 and 4).

The paper is in AEM and therefore very well done. They perform adjusted analyses to try to tease out any real effects. But you cannot infer causation with this study. They do cite one paper on ICU intubations that found no benefit and possible adverse effects of ramping. But this study did not control for … wait for it … apneic oxygenation! Remember the post this week on airway success, apneic oxygenation is awesome, do it. But at least in this paper all patients had apneic O2.

Something else left out is how long they were ramped before intubation (i wouldn’t expect 30 seconds of ramping to help), they excluded trauma patients, they didn’t talk about how ramping can prevent vomiting / aspiration, they did mention that perioperative data suggests benefit to ramping : ).

Overall this paper is worth reading and the stats get pretty thick. Maybe a journal club in the future. But we have to be very careful making practice changes or any strong assertions based on a confounded (direct quote: “we are unable to control for unmeasured confounders”) retrospective paper.