Zdravkovic, Rice and Brull take an objective look at the current evidence for cricoid pressure (CP) and professional guidelines for its use, reiterating the persistent uncertainty and general low-quality of evidence supporting use or avoidance.
- Sellick's original 1961 description is based upon significantly flawed audit data.
- There is much contradictory primary science research showing some effect of CP.
- NAP4 found pulmonary aspiration responsible for more deaths than intubation or ventilation failures, and the US ASA Closed Claims database shows it to be the third most common pulmonary event leading to claims. Thus recommendations and guidelines for the use of cricoid pressure carry very real medicolegal implications even in the absence of quality clinical evidence.
- Microaspiration in elective surgery is common (20%) but does not appear to be modified by CP.
- CP has a variable effect on the ease of intubation.
- There is no agreement on CP application technique nor even on scenarios where it should or should not be used.
- CP guidelines are variable, based on low-quality evidence and largely dependent on expert opinion.
- CP use is largely up to individual judgement, with a pragmatic approach best adopted for its application or release.
- Perhaps the greatest impact can be gained from ultrasound evaluation of gastric volume to identify those most at risk of aspiration?
Bedside risk stratification for pulmonary aspiration is probably the single greatest modifiable factor in anesthesia practice to reduce aspiration, almost certainly of greater importance than the ongoing cricoid pressure debate – which may never be conclusively resolved.summary
Why is this important?
This is the first systematic review of RCTs assessing different techniques for conducting awake fibreoptic intubation (AFOI), although the quality of evidence continues to be moderate-low.
Cabrini et al. reviewed 37 RCTs capturing 2,045 AFOI events.
What did they find?
There was no significant success difference among techniques for either local anaesthesia application or procedural sedation, including infusions or boluses of dexmedetomidine, propofol, opioids (fentanyl, sufentanil, remifentanil), ±midazolam, or sevoflurane.
Dexmedetomidine sedation resulted in the fewest desaturation events, and sevoflurane the fewest apnoea events.
Opioids used on their own (ie. without benzodiazepines) resulted in the highest patient recall, particularly remifentanil.
Also of interest...
When conducted by trained experts, AFOI is safe and effective regardless of technique and only very uncommonly results in intubation failure (0.59%) or severe adverse events (0.34%). No permanent morbidity or death was identified.
The take-home message:
When choosing a technique for awake fibre optic intubation, do what you do best – generally this will be what you and your institution are most experienced with.summary
What did they do?
Tamura and team randomised 176 elective CS patients to spinal anaesthesia with or without morphine, in addition to placebo or ultrasound-guided quadratus lumborum block (QLB).
And they found
Only intrathecal morphine significantly improved analgesia, not QLB whether performed with or without spinal morphine. Thus QLB probably does not improve analgesia further beyond current best practices.
Not so fast...
While this modest-sized RCT concluded that QLB did not improve pain after caesarean section, the conclusion is i) somewhat inconsistent with earlier studies that did show benefit, and ii) the adjuvant analgesic regime1 used may not be applicable to practice outside Japan.
The researchers administered the remaining 90 mcg fentanyl IV, along with droperidol 1.25 mg and acetaminophen/paracetamol 15mg/kg after baby delivery. An NSAID (diclofenac 50mg) was only provided when breakthrough pain was requested. ↩