Safe Use Of High-Flow Nasal Oxygen (HFNO)

The Anesthesia Patient Safety Foundation provide an excellent overview of the popular and expanding use of High Flow Nasal Oxygen (HFNO), devices which are in many cases supplanting BIPAP, and  used to provide apneic ventilation during intubation, as well as post extubation and weaning from ventilation. This review also adds some caution, in particular the danger of fire, and contraindications.



Procedural Sedation

A recent guideline from the American College of Emergency Physicians on unscheduled procedural sedation is interesting to compare with  American Society of Anesthesiologists’ views on sedation. There have been longstanding tensions between the ASA and others who administer sedation such as gastroenterologists and dentists.

The ACEP take the view that the proceduralist can give or direct giving sedation and that the level of responsiveness and ventilation are more important than the agent used (clearing the way for Propofol!). Skills are needed to rescue a patient who slips into deep sedation or general anesthesia.

The risk of gastric aspiration so central to Anesthesia practice is downplayed with reasonable evidence of how rare an occurrence it is, an issue sure to provoke controversy.



High Flow Nasal Oxygen in Immunocompromised Patients

High Flow Nasal Oxygen has become an increasingly popular alternative to non-invasive ventilation as well as use after invasive ventilation. The same devices are now used during apneic ventilation during difficult intubations or for fibreoptic intubation. Previous studies have found positive effects on ventilator free days and mortality.

However immunocompromised patients may differ and this study found that in critically ill immunocompromised patients with acute respiratory failure, high-flow oxygen therapy did not significantly decrease day-28 mortality compared with standard oxygen therapy.



Cricoid Pressure and Aspiration

A study throws doubt once again on the utility of cricoid pressure in preventing aspiration of gastric contents.

“The inclusion criteria were patients 18 years and older with a full stomach (<6 hours fasting) or the presence of at least 1 risk factor for pulmonary aspiration (emergency conditions, body mass index >30, previous gastric surgery [sleeve, bypass, or gastrectomy], ileus, early [<48 hours] postpartum, diabetic gastroparesia, gastroesophageal reflux, hiatus hernia, preoperative nausea/vomiting, and pain)”.

There was no difference in aspiration compared with a sham procedure but cricoid made intubation slower and more difficult. The authors caution that further study is needed in Obstetrics and outside the Operating Room.

However this study had a non-inferiority design that was underpowered with the low aspiration rates as well as defining a 50% difference threshold. It is unlikely to consign cricoid pressure to the history books but will perhaps confirm biases in the anti-cricoid camp!



OSA Screening in Pregnant Obese

Pregnant patients 24-35 weeks with BMI > 40 were given Obstructive Sleep Apnea (OSA) screening questionnaires (Berlin, American Society of Anesthesiologists checklist, and STOP-BANG), and the Epworth sleepiness scale. They underwent overnight sleep apnea testing; 24% had OSA.

“Established OSA screening tools performed very poorly to screen for OSA in this cohort. Age, BMI, neck circumference, frequent witnessed apneas and highly likely to fall asleep while driving were most strongly associated with OSA status in this cohort.”

OSA screening tools may need to be refined in this population.



Laryngeal Tube and Cardiac Arrest Outcome

A strategy of initial laryngeal tube insertion, compared with endotracheal intubation, was associated with greater likelihood of 72-hour survival after out of hospital cardiac arrest.

There were small differences in secondary outcomes like favourable neurological status. Airway success rates were far higher in the laryngeal tube group and this makes it difficult to compare directly as intubation successes were so low here, about 50%, quite concerning

At least once again, supraglottic airways seem appropriate as a choice of initial airway management.



Videolaryngoscopy vs. fibreoptic bronchoscopy for awake tracheal intubation

The time honoured use of fibreoptic awake intubation as the gold standard for the difficult airway comes into question in this review and meta-analysis. The results are that videolaryngoscopy for awake tracheal intubation is associated with a shorter intubation time. It also seems to have a success rate and safety profile comparable to fibreoptic bronchoscopy.

Nuances are hidden here – if insufficient mouth opening is present, fibreoptic may still be the choice, as it may be also with soiled or bloody airways. The key component is adequate airway topical anesthesia and varying recipes exist, and improper topicalization is still the main problem. Also sedation regimes vary – most commonly Propofol and/or Remifentanil, or Dexmedetomidine. The type of videolaryngoscope blade also has an impact, with highly angulated blades like the the Glidescope being favoured. Lastly a practice combining a videolaryngoscopic view with flexible fibreoptic intubation can be helpful in easily passing a tracheal tube.