When life gives you LEMONs- Predicting difficult intubations in the ED

Article:

Reed MJ, Dunn MJ, & McKeown DW. Can an Airway Assessment Score Predict Difficulty at Intubation in the Emergency Department? Emerg Med J 2005; 22(2): 99 – 102.

Main Points:

  1. Rapid assessment tools can be helpful in predicting difficult intubations in the emergency department
  1. Use of SOME elements of the LEMON (look, evaluate, mallampati, obstruction, neck mobility) approach to airway assessment MAY be helpful in predicting likely laryngoscopic view (Cormack- Lehane grade) as a proxy for difficulty of intubation. The following are more likely found in patients with high grade views (2-4).
  • large incisors
  • reduced inter-incisor distance
  • reduced thyroid to floor of mouth distance

Background:

Predicting difficult intubations is not always straightforward. At the time of publication (2005), little validation of rapid assessment of possible difficult intubations in the ED. The authors test the use of the LEMON approach as a predictor of difficult intubations, and suggest key parts of the assessment that are most helpful.

 

Details:

The study was a prospective, observational trial conducted in the UK at a teaching Emergency Department between June 2002 and September 2003.   156/177 patients intubated over that time were included in the study. Those excluded were done so because no LEMON assessment was completed. Of the remaining included, a modified LEMON assessment was completed including: LOOK- facial trauma, large incisors, large tongue, facial hair; EVALUATE- inter-incisor distance (<3 fingers), hyoid-mental distance (<3 fingers), thyroid to floor of mouth distance (<2 fingers); MALLAMPATI 1/2 versus 3/4 ; OBSTRUCTION; and NECK MOBILITY- cervical collar versus no collar. One point was assigned for each criterion that was found. If a criterion was though unassessable, a score of zero was given. Outcome was determined by laryngoscopic view as outlined by the Cormack-Lehane grading scale; grade 1 was considered an easy intubation, grades 2-4 were considered difficult. ALL intubations were successful, and if multiple attempts were used, the grade of view on the successful attempt was used. Authors used Fischer’s exact test to compare the categorical variables, Student’s t test to compare continuous data. Spearman rank sum test was used to assess correlation between categorical variables.

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Of course the patient’s blue…that’s why I’m intubating.

 

Discussing: “Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department” (Weingart SD, J Emerg Med. 2010 Apr 7)

Main Points:

  1. Patients requiring intubation should be classified by oxygenation saturation as low risk, high risk and apneic.  
  2. Reservoir face masks with oxygen set at the highest rate possible are the recommended sources of high FiO2 during preoxygenation.  
  3. All patients, if possible, should be intubated with the head-elevated position to increase safe apnea time.
  4. Consider using CPAP masks, noninvasive positive pressure ventilation or PEEP valves on a bag-valve mask in patients who cannot achieve oxygen saturations greater than 93%-95%
  5. Rocuronium may provide a longer duration of a safe apneic period in patients with a high risk of desaturation.
  6. A nasal cannula set at 15 L/minute is effective at providing oxygenation during the apneic period.

Background:

Intubation is a vital procedure to the Emergency Physician.  Yet there is more to it than just placing an endotracheal tube.  There is the setup, positioning, oxygenation, sedation, checking tube placement, and more.  On top of this, there is the underlying illness to consider.  The truth is, the majority of patients intubated in the Emergency Department (ED) are sick.  Something is very physiologically wrong, and they are not maintaining adequate oxygenation.  It becomes your job to do this for them.  The authors in this article did an extensive literature review on pre-intubation and peri-intubation techniques which reduce the risk of hypoxia in the adult patient requiring intubation in the ED.   Continue reading

ED Ventilator Settings

Quality Control editors at work.

Quality Control editors at work.

All excited for intubation but forget to optimize the ventilatory settings?

Important for those that are not rapidly taken away to the ICU.

Ventilation
Tidal Volumes: low tidal volumes 6 ml/kg (ideal body weight) even without acute lung injury is even beneficial.  Study by Determann et al. 2010 Critical Care.  Looked at 150 patients, randomized trial of 10 vs 6 ml/kg.  Development of Acute lung injury in 13.5 in the 10 ml/kg group and 2.6 in the 6 ml/kg group.  Stopped early because of difference.
Respiratory Rate: Minute ventilation is RRxTV.  You want a MV of 5-6L/min in a normal patient, but if need to increase for metabolic derrangement may need much higher.  Permissive hypercapnea is okay in those with ARDS.  Caution in those with brain injury and severe metabolic acidosis.  Don’t go higher than RR of 35.  Keep ph>7.15, as done in ARDSnet. Continue reading