Are We Missing Obstructed Airways in Cardiac Arrest?

The “H’s and T’s” are a familiar mnemonic to remember potential causes of cardiac arrest. A patient in Florida added a twist to them with implications that are worth examining.

The patient: a 46-year-old woman who arrested at home. Family members provided CPR, but when rescuers arrived she was in asystole. The crew began standard ACLS care, including bag-valve mask ventilation and compressions with an AutoPulse.

With latitude in airway selection, the scene officer chose an i-gel supraglottic airway. This produced chest rise, but unable to get a good end-tidal reading, providers pulled it. Tubing was unsuccessful, so they continued the bagging through transport.

At the emergency department, a physician finally found another H: a piece of ham stuck in the woman’s throat. An obstructed airway had triggered her cardiac arrest. But in using the supraglottic airway, responders didn’t see it.

The question, then: Are we missing obstructed airways when using SGAs on cardiac arrest patients?

“I think we do, though I think it’s rare,” says Kathy Schrank, MD, medical director for the City of Miami Department of Fire-Rescue, who spoke on the case at this year’s Gathering of Eagles. “But we won’t really know. We terminate a lot of unsuccessful resuscitations in the field where we’re never going to know. We don’t really have a good way to find out. But I worry that in some patients we’re missing a potentially treatable reason for arrest.”

The Choking Trap

In this area, choking can be a trap for EMS. Family members of the victim in Schrank’s case didn’t realize that’s what was happening; other cases may be unwitnessed entirely. And in the urgency of responding to what ultimately becomes a cardiac arrest, that culprit may not be caught. 

“When we don’t actually see the person giving the choking sign or have a family member tell us they were choking, we might just put in an SGA without taking a look with a laryngoscope, and we may miss it,” says Schrank, a professor of emergency medicine at the University of Miami’s Miller School of Medicine. “During cardiac arrest we’re working so hard to start chest compressions and not interrupt for anything, it can be several minutes into the arrest before this would be recognized. The chest compressions make it much harder to get a good quality tracing on the capnography waveform; they make it much harder to assess the airway clinically by seeing chest rise; and they make it much harder for the person bagging the patient to feel the resistance and realize they’re not getting air into the chest.”

The same could hold true, incidentally, with BVM use. And in systems with passive oxygenation-ventilation protocols—i.e., that just use a high-flow nonrebreather mask with no direct bag-mask ventilation or intubation attempt—it could be missed for a long time.

The solution isn’t to stop or pause compressions; it’s to remain highly vigilant about the A in that CAB and be sure to check for foreign bodies.

“We need to think about A, pay attention to it, and during one of the pulse checks, the airway provider needs to really bag and look,” says Schrank. “Look at the waveform, look at the chest, and make sure you’ve really checked for a patent airway.”

Your every-two-minutes pulse check pauses are a good opportunity for this, if you’re not getting anywhere with your patient. A laryngoscope can be quickly inserted with minimal interruption of compressions.

All the major airway assessment mnemonics (LEMON, MOAN, RODS) remind providers to check for obstructions, Schrank notes (see Table 1), and in Miami the idea is reinforced in airway educational modules (best practice: use a simulator that can depict an obstructed airway). Personnel also go through a difficult-airway course at the University of Miami that employs high-level simulation.

In the ham case, the crew was naturally devastated when they realized at the ED there had been an undiscovered airway obstruction.

“I think probably the ham was moving around in the pharynx and wasn’t completely obstructing at all times—maybe the chest compressions helped move it out of the way,” says Schrank. “But at some point it got back in the way. And the SGA doesn’t necessarily prevent that. Although we think it seals, during lifting and moving and defibrillation, it’s easy for a patient to move a little bit, and maybe the i-gel comes unseated for a couple of seconds. Then something can move in that wasn’t there initially. We have no way to know.”

A reminder, then, to really check for chest rise; feel for compliance when giving breaths; and obtain waveform capnography with SGAs. If you’re not sure of a patent airway, say something, and if you can’t get ROSC, consider the A along with the H’s and T’s.