This case and pearls are provided by Dr. Samia Farooqi. Thank you so much for the excellent case! Edited by Michael Macias.
A middle aged female with a history of cirrhosis complicated by hepato-pulmonary syndrome and severe diastolic dysfunction presented to the ED in acute respiratory distress. The patient was brought in by medics with an initial O2 saturation at a concerning level of 78%. She appeared panicked and tachypneic. She was immediately placed on a non-rebreather face mask for temporizing measure as respiratory therapy was paged for stat Bipap. However as her O2 saturation continued to remain low, she became progressively more agitated and anxious.
Once Bipap was placed, this too appeared to only be a temporizing measure as the patient continued to intermittently tear off the face mask leading to desaturations into the 70s. Amongst all the hullaballoo, a portable CXR was obtained which revealed profound pulmonary edema:
It was clear that this patient would require intubation however there was significant concern for rapid desaturation during RSI. A decision was made to administer 1mg/kg IV ketamine while the patient remained on Bipap to assist with oxygenation. Following administration, the patient became quite compliant with her NIPPV, allowing her O2 saturation to climb back up to a safe 96-98%. After a few minutes of continued oxygenation, the patient was properly positioned (ear-sternal notch), paralyzed with succinylcholine and successfully intubated on first pass without desaturation.
This case is a perfect example of delayed sequence intubation, which Scott Weingart refers to as “procedural sedation for pre-oxygenation.” In the difficult-to-oxygenate patient who is anxious and/or delirious, this may be your best option to create a period of safe apnea during intubation. In his 2011 Journal of Emergency Medicine paper titled 'Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department', he breaks down DSI into four steps:
1. Administer 1-1.5mg/kg IV ketamine by slow IV push.
2. Once the patient is calm/dissociated, apply NRB or NIPPV.
3. Once 100% O2 sat is achieved, allow the patient to breathe high FiO2 oxygen for an additional 2-3 minutes to allow for adequate alveolar de-nitrogenation.
4. Administer a paralytic and intubate the patient, with a nasal cannula set @15L/min in place during the entire apneic period.
Weingart notes that often when patients are sedated with ketamine and become compliant with oxygenation, they often have such drastic improvements in respiratory parameters that intubation can be avoided completely.
Just remember that RSI isn't for everyone and when you can't adequately oxygenate a patient prior to intubation secondary to agitation/delirium, consider 'procedural sedation for oxygenation' and delayed sequence intubation as an alternative option. Increase your safe apnea time with pre-oxygenation and shoot for no desaturation! We know that when @^#@ hits the fan we have a decline in our cognitive abilities as well as motor skills and this is where errors will occur. So prevent this potentially deadly situation and pre-oxygenate like a champion (To understand more on our response to stress and potential for cognitive deterioration, listen to this excellent podcast regarding lessons from combat).
If you are at all interested in DSI, check out the all-things DSI page at EM Crit:
More information on topics related to this clinical case:
- Podcast on Non-invasive positive pressure ventilation by Scott Weingart
- Preoxygenation and Apneic Oxygenation at Rebel EM
- DSI Protocol from Dr. Rob Bryant at PHARM
- Ketamine does not lead to worse outcomes in patients with increased ICP
Weingart, S. (2011). Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department. Journal of Emergency Medicine, 40 (6): 661-667.