Dr Hector Thomson
Emergency Registrar

Peer review: Dr David McCreary
On a recent anaesthetic rotation during a paeds ENT list I heard a delightful description of laryngospasm. “Oh they are just a little squeaky… give them some PEEP it’ll be fine.” I immediately thought of the Toy Story 2 character, Wheezy, the adorable penguin who gets put on the shelf when his squeaker is broken! He tries squeaking for help but no one can hear him and the dust aggravates his condition!
It took me a fair few lists before I stopped fearing the squeak!

What is laryngospasm?

Laryngospasm is potentially life-threatening closure of the true vocal cords resulting in partial or complete airway obstruction. This is a primitive protective airway reflux that aims to protect against aspiration but can cause life threatening hypoxia.

Anatomy revision

In laryngospasm either the true cords alone or the false cords slam shut and close the glottis. Most laryngeal reflexes are produced by stimulation of the superior laryngeal nerve which provides sensory innervation to the supraglottic region. This is a branch of the vagus nerve. The muscles involved are the lateral cricoarytenoid and the thyroarytenoids (adductors) and the cricothyroid (vocal cord tensors). The cricothyroid muscle is the only tensor of the vocal cords. Gentle pressure from a jaw thrust may overcome moderate laryngospasm.

Image: https://teachmeanatomy.info/neck/viscera/larynx/muscles/

The AIME Airway Course website has some amazing videos and images on airway anatomy. The vocal cords are white and triangular. Anteriorly sits the epligottis, laterally the aryepiglottic folds and posteriorly the cuneiform and corniculate tubercles and the interarytenoid notch.

Image: https://aimeairway.ca/announcement/62/excerpts-from-airway-physiology-and-anatomy-a-deep-dive-chapter-in-airway-management-in-emergencies-the-infinity-edition

Image: Paediatric Anaesthesia Digital Handbook

What causes it?

Local causes:
  • Extubation: children with URTI symptoms (beware the snotty child)
  • Airway manipulation (especially when under light anaesthesia)
  • ENT procedures (usually involves lots of suctioning and prodding around the airway!)
  • Secretions/blood/vomit in airway
  • Foreign body
  • Near drowning
Systemic causes:
  • Drugs (rarely associated with ketamine sedation)
  • Tetanus
  • Hypocalcaemia
  • Vocal cord dysfunction
Risk factors:
  • Past history
  • Asthma
  • Smoking
  • GORD
  • Recent URTI

In the ED we will encounter this while performing procedural sedation. The feared situation being IM ketamine sedation then laryngospasm that doesn’t settle with first line measuring. Leading to a scramble to gain IV access. There is also a case report from RCH of a case during nitrous oxide sedation.

🤓 TOP TIP: Give your ketamine slowly to reduce complications (Credit: Dr Shaun Baxter) Ed: In particular this avoids the ‘stunned apnoea’ that a fast push can cause – which can cause some 🤨  in the room.

How common is it?

Most of the studies are on the operating room. Bellolio in 2016 reported the rate of laryngospasm in ED procedure sedation is bout 1.1 per 1,000 adult patients. In kids it is estimated around 3.9 per 1,000 sedations and almost all were in ketamine sedations.

🤓  Ed: Andy Neill and I reviewed this 2017 paper by Bhatt et al. on the RCEMLearning Podcast back in February 2018. Of note this big dataset of over 6000 procedures from 6 tertiary paediatric emergency departments in Canada found the rate of laryngospasm to be a mere 0.1% (4 events overall).

How do we recognise it?

Laryngospasm exists on a spectrum from partial to complete obstruction and occasionally presents atypically and without warning signs
🚨 Early warning = Loss of end-tidal CO2 🚨

Exam findings
  • Inspiratory stridor/airway obstruction
  • Increased inspiratory efforts/tracheal tug
  • Paradoxical chest/abdominal movements
Complete obstruction:
  • No chest wall movements
  • No airway sounds
  • Inability fo ventilate
Late signs:
  • Desaturation
  • Bradycardia
  • Central cyanosis
In 189 cases reported to the Australian Incident Monitoring Study:
  • 77% were clinically obvious
  • 14% presented as airway obstruction
  • 5% as regurgitation
  • 4% as desaturation

My Approach  

PAUSE: Proceduralist stop the procedure

PERSONEL: Call for help – the situation can rapidly deteriorate An airway crisis needs a team and you will need but a team leader and an expert to manage the airway + drugs drawn up and equipment prepared

POSITION: Jaw thrust/Chin lift + Suction blood and secretions

PEEP:100% O2 via mask with PEEP valve Consider a guedel airway

PRESSURE POINT: Larson’s point bilaterally while forming jaw thrust

PROPOFOL: 0.5mg/kg IV to deepen sedation/anaesthesia If rapidly developing hypoxia proceed to next step

PARALYSE:1.5mg/kg IV and intubate -> 3-4mg/kg IM has been suggested but remember you can put an IO in quickly Give atropine 20mcg/kg as bradycardia can develop with hypoxia. The anaesthetic approach has been suggested to get a low dose suxamethonium to break the spasm. My thought is if I am giving a paralytic for laryngospasm it is an airway emergency requiring intubation.

What complications can arise?

  • Desaturation (60%)
  • Bradycardia (6%)
  • Negative pressure pulmonary oedema (4%)
  • Aspiration (3%)
  • Cardiac arrest (0.5%)
  • Ischaemic brain injury
  • Death
Side Note - Where is Larson's Point?
In 1998 Dr Larson credits a Dr N. P Guadagni with showing him the technique 40 years earlier. Seems a bit rough for Dr Guadagni that he doesn’t at least get a partial naming credit! He describes the position as: “This notch is behind the lobule of the pinna of each ear. It is bounded anteriorly by the ascending ramus of the mandible adjacent to the condyle, posteriorly by the mastoid process of the temporal bone, and cephalad by the base of the skull. The therapist presses very firmly inward toward the base of the skull with both fingers, while at the same time lifting the mandible at a right angle to the plane of the body (i.e., forward displacement of the mandible or “jaw thrust”). Properly performed, it will convert laryngospasm within one or two breaths to laryngeal stridor and in another few breaths to unobstructed respirations.” Larson admits he doesn’t have a good scientific reason for why it works but postulates it may be forward displacement of the mandible, severe pain from the pressure applied to the facial nerve or even the glossopharyngeal nerve through the parotid.

Image: from Larson’s original paper

Preparation

Don’t Forget the Bubbles have a fantastic section on procedural sedation. In it, they include a flowchart to be filled out for every patient prior to sedation. All the paediatric anaesthetists I worked with would check they had sux and atropine to hand and some would draw up emergency drugs to ward off the evil laryngospasm spirits. In ED I think this is a bit of a waste of medications but for every procedural sedation, I ensure I have sux, atropine and adrenaline to hand along with needles to draw them up.

🤓  Ed: I don’t have the drugs drawn up (massive waste given the frequency of the event), and I don’t have them on the side either. I do, however, specifically run through the steps we’d take for a laryngospasm event with the nursing staff as part of the pre-procedure timeout and in that I include that I could ask for sux and they should have eyeballed it and know where to get it immediately if needed.

Source: Don’t Forget The Bubbles

So remember – just stay calm and don’t fear the squeak!

References

FOAMed Resources
  1. First10 EM
  2. Don’t Forget The Bubbles
  3. Life in the Fast Lane
  4. McCreary D, Neill A. NewinEM – Risk Factors for Adverse Events in Emergency Department Procedural Sedation for Children.
    RCEMLearning Podcast February 2018.
Papers
  1. Hernández-Cortez E. Update on the management of laryngospasm. J Anesth Crit Care Open Access. 2018;8(2):1–6. DOI: 10.15406/jaccoa.2018.08.00327
  2. N D’souza, R Garg. Perioperative Laryngospasm – Review of literature. The Internet Journal of Anesthesiology. 2008 Volume 20 Number 1. Laryngospasm With Apparent Aspiration During Sedation With Nitrous Oxide Babl, Franz E. et al. Annals of Emergency Medicine , Volume 66 , Issue 5 , 475 – 478. doi: 10.1016/j.annemergmed.2015.04.029
  3. Bellolio MF, Gilani WI, Barrionuevo P. Incidence of Adverse Events in Adults Undergoing Procedural Sedation in the Emergency Department: A Systematic Review and Meta-analysis. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine. 23(2):119-34. 2016. doi: 10.1111/acem.12875
  4. Visvanathan T, Kluger MT, Webb RK, Westhorpe RN. Crisis management during anaesthesia: laryngospasm. Qual Saf Health Care. 2005 Jun;14(3):e3. doi: 10.1136/qshc.2002.004275. PMID: 15933300; PMCID: PMC1744026.
  5. Al-Metwalli RR, Mowafi HA, Ismail SA. Gentle chest compression relieves extubation laryngospasm in children. J Anesth. 2010;24(6):854-857. doi: 10.1007/s00540-010-1036-9
  6. Philip C. Larson; Laryngospasm-The Best Treatment . Anesthesiology 1998; 89:1293–1294 doi: 10.1097/00000542-199811000-00056
Hector Thomson

Hector Thomson

Emergency Registrar

Hector (the one on the left) is an Emergency Medicine Advanced Trainee at The Alfred. He’s still clinging to the basic science knowledge he gained during primary exam prep and enjoys shoulder dislocations, trauma, rugby union, fresh pasta and good gin. He doesn’t like vague allergies or cats.