Airway

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.

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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.

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  • 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.

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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.

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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.

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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

Failed Laryngoscopy and Intubation

The full text review is gated for non subscribers but provides a thoughtful reflection on terminology, preparation, skill acquisition, VortexApproach , SGAs, eFONA etc.

Some practical advice is also offered on topics such as apneic nasal oxygenation to prolong time to desaturation, bougie assisted supraglottic airways, and the steps in emergency front of neck airway (eFONA), reviewed elsewhere in this blog – blog link

Optimimizing using ‘best effort” in each part is emphasized: facemask, supraglottic airway, and intubation, leaning on the philosophy of the Vortex Approach ( link )

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Preoxygenation for Intubation in ICU

A post-how analysis of a previous trial compares Preoxygenation strategies for critically ill patients to minimize hypoxia. They compared bag/mask, non-rebreather, non-invasive ventilation, and high flow nasal oxygenation.

While they found that the main determinants of hypoxemia during endotracheal intubation may be related to critical illness severity and to preexisting hypoxemia, the best performer was non-invasive ventilation.

Post hoc analyses are maligned as “data dredging” that are not designed for these secondary results, but they can also extract useful data. This implies further randomized studies should be done to confirm these findings.

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Extubation in Difficult-to-Wean Patients

This systematic review and meta-analysis aimed to identify strategies for extubating patients deemed difficult to wean from mechanical ventilation due to delirium, agitation or anxiety.

The overall quality of the heterogeneous studies was poor, but Dexmedetomidine seems to be associated with a shorter time to extubation and ICU length of stay. The authors conclude that low quality evidence supports the use of Dexmedetomidine in patients deemed difficult-to-wean due to agitation, delirium, or anxiety.

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OR Fires

Another (gated) review seeks to bring attention to the issue of Operating Room fires. It reviews the “fire triangle” of ignition, fuel and oxidizer; the contribution and risks of such factors as electrosurgery, laser, drills, fibreoptic light sources, defibrillators, alcohol skin prep, intestinal gas, drapes and oxygen.

Oxygen is one of the key modifiable factors and advice is to maintain FiO2 below 30%. Over 80% of all OR fires are in surgery on the head, neck and upper chest and a similar percentage under sedation, where local oxygen concentrations can easily increase with nasal cannula flow above (or even less with draping) 4l/min. A lethal combination of oxygen, drapes and alcohol based preps can develop waiting for the cautery to spark a fire, particularly lethal near the patient airway.

Should a fire occur, recommendations are to stop the flow of all airway gases, disconnect the breathing circuit, remove tracheal tubes in airway fires and irrigate with saline, and remove burning materials, extinguish the fire and restore room air breathing.

Fire risk should be included in checklists at briefing and/or timeouts.

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A (free!) guideline is also available from the FDA here