Allergic Angioedema 


Peanut Allergy Strikes Again

Dr. Jordan Singer

Case summary:


An ALS crew responded to 40s woman at an allergy clinic with report of an allergic reaction.  The patient has a known allergy to peanuts and the clinic was doing desensitization and exposed the patient to peanuts.  The clinic had already given two doses of IM epinephrine prior to EMS arrival.  The crew found the patient covered in an hives with audible wheezes.  She reported that her throat felt tight.  The crew immediately gave another dose of 0.5mg IM epinephrine.  They then treated with nebulized bronchodilators while also requesting back up due to concern she would need rapid sequence intubation.  They then extricated her to the rig where they gave diphenhydramine and steroids.  The patient then started having extreme nausea.  Back up arrived and the patient reported that despite all this treatment, her symptoms were worsening.  The crew decided to perform RSI due to concern for impending loss of airway from angioedema.  The crew administered ketamine and rocuronium and were able to successfully intubate the patient.  The endotracheal tube placement was confirmed with end-tidal waveform capnography and a complete set of vitals were obtained after intubation.


Vitals: BP 150/89,  HR 115,  RR 16,  Sat 94%,  ETCO2 46 mmHg


Patient was monitored closely for the transport to the receiving hospital and did not have any changes in her vital signs. 


Highlights of the case:

The most important treatment in anaphylaxis is immediate IM epinephrine.

Anaphylaxis is defined as an allergic reaction involving two or more organ systems.  This patient had involvement of her skin, airway, lungs and gastrointestinal tract, so her presentation meets this definition.  The most important treatment in anaphylaxis is IM epinephrine.   This should be given as soon as possible, and we should never delay this for extrication or other treatments for allergic reactions.  We can also re-dose this every 5 minutes as needed to treat her symptoms.  Even though this patient had already received two doses of epinephrine, her symptoms were not improving so the crew was correct to immediately give her an additional dose.  They also gave her adjuncts such as albuterol, steroids, and diphenhydramine after they got epinephrine on board.  This was all perfect!


Early airway intervention is key for angioedema.

Angioedema can progress very rapidly.  Once the angioedema progresses far enough, the only way to obtain an airway might be a surgical cricothyrotomy.  For this reason, we should have a low threshold for early placement of an advanced airway.  The only chance the patient has for successful placement of an endotracheal tube might be if EMS places the tube since their airway might close off prior to arrival at the hospital.  Given that angioedema often involves the glottic structures and vocal cords, supraglottic devices are often insufficient to maintain an airway in the setting of angioedema, so we should be reaching for an endotracheal tube in these situations.  An important additional consideration is that the cords can be swollen, which might prevent us from successfully passing standard endotracheal tube sizes.  We should consider selecting a tube that is a half-size smaller than we otherwise would have selected.  The last consideration is that sometimes the safest way to place an advanced airway in the setting of angioedema is by awake intubation with a fiberoptic scope, which cannot be done in the field in our system.  The decision to manage the airway in the field vs delay for awake intubation in the hospital depends on many factors including how quickly the patient is progressing and how close to the receiving facility you are.  Do not hesitate to involve medical control in these decisions since it can be very nuance.  This crew felt that the patient was going to progress rapidly and wisely chose to perform rapid sequence intubation in the field to control the airway before the angioedema progressed further. 


Always confirm advanced airway placement with continuous waveform capnography

Waveform ETCO2 is the gold standard for correct positioning of an advanced airway and is mandated for all prehospital advanced airways.  This includes surgical airways, endotracheal tubes and supraglottic devices.  Not only does to prove our tube is in the airway, but it also helps us monitor for ETT dislodgement.  Due to the nature of what we do which includes difficult extrications and potentially bumpy rides in the back of an ambulance, ETT we place in the field are at higher risk for dislodgement than tubes in the hospital.  For this reason, we need to monitor and document that the ETCO2 waveform remains intact during ETT placement, all patient movements and upon transfer of care in the hospital.


Ensure good post intubation sedation.

Our protocol utilizes rocuronium as the paralytic for rapid sequence intubation.  This is a non-depolarizing paralytic that paralyzes patients from 30-60 minutes, which is longer than the sedative we usually use, ketamine.  It is important to remember that paralysis without sedation is inhumane.  We cannot wait for patients to move as a sign of waning sedation since the patient will be paralyzed for so long.  For this reason, our protocol mandates re-sedating the patient 15-20 minutes after the induction dose at the very longest to prevent paralysis without adequate sedation.  We also should make sure that we notify the receiving facility when we paralyzed the patient and the time of the last sedative dose was so that there is not a lapse in sedation during or shortly after patient handoff.