The three boys get together again to talk about the papers of the month.
Semler et al, 2017.
Clinical question.
In critically ill adults requiring endotracheal intubation, does the ramped position increase the lowest oxygen saturation during rapid sequence induction compared to the supine sniffing position.
Design.
- Multi-centre study involving four tertiary hospitals.
- Randomisation in a 1:1 ratio using computer generated blocks, seal envelopes assigned treatment groups and were opened on decision to enrol in the study.
- All patients were simultaneously enrolled in a second study involving the use of intubation checklists.
- 80% power to detect a 5% difference in the lowest oxygen saturation level with an alpha level of 0.05, 260 participants required, 260 patients enrolled on an intention to treat basis.
Setting.
Patients in critical care.
Conducted in the United States of America.
Population.
- 60% were intubated for hypoxia.
- Exclusions were intubation during cardiac arrest, patients requiring cervical spine precautions, and patients requiring urgent intubation. Patients were also excluded if clinicians thought a specific position was required for the procedure to be safely performed.
- All patients received sedation and neuromuscular blockade.
- BMI and use of video laryngoscopy were similar.
Intervention/control.
- Ramped position was defined as 25 degrees head up, the occiput was positioned over the end of the mattress, face parallel to the ceiling, sniffing position/ear to sternal notch was achieved using additional pillows or blankets.
- The sniffing position was achieved by placing pillows or blankets under the head to flex the neck forward of the torso and then extension of the neck. Patients were kept supine and pillows under shoulders were not allowed.
- There was no control over the pre-oxygenation position, position was at the operators discretion until the point of induction when the patient had to be positioned according to the assigned treatment arm.
Outcome.
- Primary outcome was the lowest oxygen saturation between induction and two minutes after successful intubation. There was no difference (p value 0.027) between the lowest oxygen saturation in either group.
- Secondary outcomes;
- First pass success 4% in the supine group vs 76.2% in the ramped group (not statistically significant, and not powered for this outcome P value .02). The glottic view obtained was worse in the ramped group.
- A trend towards improved oxygenation in the more severely hypoxic patients, but not powered to look at this subgroup.
Author's conclusion.
The ramped portion does not appear to improve oxygenation during intubation and may result in a worse glottic view and lower the first pass success.
Strengths.
- Possibly the first randomised study on intubation position in a critically ill population.
- Multi-centre study.
- Sub-group analysis of operator experience did not have any impact on the results.
Weaknesses.
- Non-blinded study, however blinding impossible in this context.
- The study does not inform us on the optimal position to pre-oxygenate.
- Type of laryngoscope was not controlled, but blade type was similar between groups.
- Pre-oxygenaion position is not controlled for and may confound results.
- It is not clear if the use of a checklists in the parallel study could have confounded the data from this study.
- 53% of patients were ventilated through their apnea, this may also confound the data in regard to patients that were apneic throughout the intubation process.
- There were 46 exclusions, around 20 were in extremis and it is unknown whether there may have been benefit of ramped position in these cases. I suspect these cases may have been electively intubated head up.
Bottom line.
This study did not demonstrate a benefit in oxygenation during RSI in the ramped position over the supine position and worsened glottic view and first pass success.
Links.
https://www.ncbi.nlm.nih.gov/pubmed/28487139
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