Weingart
Delayed Sequence Intubation: A Prospective Observational Study
Weingart, Annals of Emergency Medicine;2014; published online. doi:10.1016/j.annemergmed.2014.09.025
Clinical Question
- In patients who require emergency intubation and are not tolerating pre-oxygenation, does the use of ‘delayed sequence intubation’ (DSI) improve pre-intubation oxygen saturations (SpO2)?
Design
- Prospective observational case series
- non-randomised
- non-blinded
- convenience sample
Setting
- 3 hospital in USA/Denmark
- Level 1 trauma centre or quarternary referral centre
- Study period: May 2011 to December 2013
Population
- Inclusion:
- Adult patient spontaneously breathing who were required to have emergency intubation
- Not predicted to have difficult airway
- Did not tolerate pre-oxygenation despite maximal conventional attempts
- 62 patients included in analysis out of 64 enrolled
Intervention
- Ketamine
- Initial dose 1mg/kg, followed by 0.5mg/kg aliquots until dissociated
- Then placed ≥30 degrees head up and pre-oxygenated with non-rebreather mask and nasal cannula
- If SpO2 <95% then changed to CPAP 5-15cm H2O
- 39 patients received pre-oxygenation with CPAP
- 23 patients did not require CPAP
- After 3 minutes paralysed with suxamthonium/rocuronium and intubated after further 45-60 seconds
Control
- No control group
Outcome
- Primary outcome
- Difference in SpO2 after pre-oxygenation with:
- a) standard attempts
- b) ketamine (just prior to administration of muscle relaxation)
- significant increase post ketamine
- 88.9% vs 98.8% (increase of 8.9%, 95% C.I. 6.4-10.9)
- Difference in SpO2 after pre-oxygenation with:
- Secondary outcomes:
- Subgroup analysis
- SpO2 after pre-oxygenation with ketamine in patients with initial SpO2 ≤93% after pre-oxygenation with standard attempts
- all increased SpO2 to >93%
- SpO2 after pre-oxygenation with ketamine in patients with initial SpO2 ≤93% after pre-oxygenation with standard attempts
- Complications
- No patients had pre-muscle relaxant apnoea, peri-intubation emesis, cardiac arrest or death
- 2 patients SpO2 decreased after attempting pre-oxygenation with ketamine
- decrease from 99% to 98% and 95% to 93% respectively
- both of these patients received pre-oxygenation by nonrebreather masks without nasal cannula oxygen during their dissociation
- Subgroup analysis
- Post-hoc analysis
- 2 patients with asthma improved sufficiently with pre-oxygenation with ketamine and CPAP that decision made not to intubate them
Authors’ Conclusions
- DSI safely allowed the provision of pre-oxygenation to patients who did not tolerate pre-oxygenation with traditional methods
Strengths
- Multi-centre
- Prospective
- Standard protocol for use of DSI
- Sensitivity analysis performed for possible non-parametric distribution
Weaknesses
- No control group
- Non blinded
- Convenience sample – therefore possibility of selection bias although authors comment that independent research fellow did not find evidence supporting this.
- DSI performed by clinicians with extensive experience of ketamine sedation and therefore results may not represent expected outcomes in less experienced hands
The Bottom Line
- In a prospective observational study of patients requiring emergency intubation who did not tolerate pre-oxygenation with traditional methods, the practice of DSI significantly improved oxygen saturations prior to intubation. A RCT is warranted, comparing the use of DSI with the use of other techniques for achieving pre-oxygenation, when traditional methods have failed. In the mean time, on the basis of this level 4 evidence I will use the practice of DSI in selected cases.
External Links
- [article abstract] Delayed Sequence Intubation: A Prospective Observational Study
- [further reading] Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department by Weingart
- [further reading] EmCrit Page – Everything you need to know about DSI
Metadata
Summary author: @davidslessor
Summary date: 3rd November 2014
Peer-review editor: @DuncanChambler