Airway

Pressure Support vs T-Piece Ventilation Strategies During Spontaneous Breathing Trials

All modern guidelines are in agreement with daily interruption of sedation in the ICU and spontaneous breathing trials but weaning strategies can differ.

This study found: “a spontaneous breathing trial consisting of 30 minutes of pressure support ventilation, compared with 2 hours of T-piece ventilation, led to significantly higher rates of successful extubation. These findings support the use of a shorter, less demanding ventilation strategy for spontaneous breathing trials.”

link

Cannula based cricothyrotomy

Most experts have shifted to the scalpel technique with bougie for emergency front of neck airway (eFONA).

This high fidelity lab simulation however showed a lesser chance of failure with a cannula based technique and using a Rapid‐O2® cricothyroidotomy insufflation device.

With proper training the authors suggest that there is still a strong case for using a cannula based technique. Much anatomical distortion and difficulty has often been reported with locating the cricothyroid membrane especially in the obese as well as misplacement of the tube.

link

i-gel® insertion and cricothyroid membrane identification

This small study examined cricothyroid membrane identification in adult females, whose anatomy is less pronounced than males. They concluded:

“The presence of the i-gel® improved accuracy of identifying the cricothyroid membrane using palpation in females. The cricoid cartilage was pushed ventrally by the i-gel® in the hypopharynx, creating a more palpable prominence. It may therefore be advantageous to retain a sited supraglottic airway, rather than remove it, before performing emergency cricothyroidotomy”.

link

Awake Fiberoptic Intubation Protocols in the Operating Room

Many different protocols of topical anesthesia and sedative agents have been used for fibreoptic intubation in the anticipated difficult airway, and were reviewed in this meta-analysis.

Intubation failure occurred in 0.6%, and severe adverse events in 0.3% with no permanent sequelae or death.

There were no differences in different methods of local anesthesia, and all sedation methods were equivalent.

Desaturation was similar with Remifentanil or Propofol, amd apnea was lower with Sevoflurane vs. Propofol. Desaturation was lower with Dexmedetomidine compared to opioids and Propofol with or without Midazolam.

The authors conclude: A high degree of efficacy and safety was observed with minimal differences among different protocols; dexmedetomidine might offer a better safety profile compared to other sedatives.

link

ER Airway Assessment using Mallampati Score

This literature review surveyed use of the Mallampati score in Emergency departments prior to airway control or procedural sedation. It was concluded that Mallampati score is inadequately sensitive for the identification of difficult laryngoscopy, difficult intubation, and difficult bag-valve-mask ventilation.

link

  • Airway assessment is a series of measures, Mallampati being just one, and known to have inadequate sensitivity or specificity by anesthesia providers. The blog link below includes a full text link to a JAMA comprehensive review of difficult intubation prediction.

blog link

Rocuronium before Mask Ventilation

Another randomized study supports just giving the neuromuscular blocking agent before testing mask ventilation as it ultimately leads to better mask ventilation and earlier intubation.

This practice is in line with modern expert recommendations, despite running counter to previous teachings. The airway is already often lost with anesthesia induction before the relaxant and muscle relaxation aids in ventilation.

link

Pressure Controlled Ventilation for Pediatric Facemask

From an early view study in Pediatric Anesthesia: At an inspiratory pressure of 13 cmH2O, pressure‐controlled ventilation may be more effective than manual ventilation in preventing gastric insufflation while providing stable ventilation in children.

This is also a useful maneuver to free both hands to maintain a patent airway without needing another staff member to squeeze the breathing bag, and could usefully be further studied in adults in difficult mask-ventilation scenarios. Modern anesthesia machines provide such modes as Pressure Control and Pressure Control-Volume Guaranteed.

link



Difficult Intubation Prediction

Anesthesiologists take an intuitive eyeball approach to anticipating difficult intubations, but many formal scores and assessment tools of varying sensitivity and specificity exist, like the Mallampati or Wilson scores. This full text JAMA review looks at some of these in predicting difficult intubation.

The best predictors were an inability to bite the upper lip with the lower incisors, a short hyomental distance, retrognathia, or a combination of findings based on the Wilson score.

The inability to bite the upper lip with the lower teeth was the best predictor.

A good full text review at this link