Article Notes
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A specialized obstetric anesthesiologist was defined as having completed an obstetric anesthesia fellowship or specialist practice for at least 5 years with 33% full-time obstetric anesthesia case-load. ↩
- 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?
Chris Tan
Who are EM3?
EM3 or ‘East Midlands Emergency Medicine Educational Media’ is an online emergency medicine educational resource, based out of Leicester Royal Infirmary ED. While their web presence is the foundation of their online resources, they are most interesting for the very successful way they translate emergency medicine research and education through multi-platform social media and FOAMed.
So, what happened?
In late October there were two inadvertent errors in educational resources simultaneously posted by EM3 to Twitter, Instagram, Facebook and Reddit. The errors were quickly identified and corrected, but despite this the incorrect posts continued to be shared, reaching some 15,000 people.
Edwards and Roland carefully describe the events, the approach EM3 took to correcting the errors, and analysis of the potential impact. They discuss the challenges when correcting what is by its very nature a dynamic resource, and one for which there is limited control once released. EM3 discuss the additional oversight added to their peer review process in response.
Their report is a cautionary tale for the FOAMed community and a useful resource for avoiding and managing SM errors when they inevitably occur.
Don’t be hasty...
Acknowledging that the reach and velocity offered by social media and FOAMed also bring accuracy and credibility concerns, traditional academic publishing is not without its own problems.
Whether outright academic fraud, replication crises or information overload, we already know that incorrect medical information persists for decades after being disproven. This is not a new problem, though FOAMed does accelerate the speed and scope for both good and bad.
Between the lines
The context of the article’s publication reveals the ongoing tension between FOAMed and the reality of traditional academic publishers, such as the BMJ: ‘Learning from mistakes on social media’ is not itself open access...
Daniel Jolley
There is ever greater interest in mitigating medical errors, particularly through cognitive aids and checklist-system long-used in the aviation industry.
Jelacic and team instituted a computerised pre-induction checklist, using an observational before-and-after study design across 1,570 cases. This is the first study of a computerised anaesthesia checklist in a real clinical environment.
They found an absolute risk reduction of almost 4% of failure-to-perform critical pre-induction steps, along with reduction in non-routine events and several examples of pre-induction mistake identification through checklist use.
Although the researchers claim the results “strongly argue for the routine use of a pre-induction anaesthesia checklist” this overstates the case a little. This study, like many similar, struggles with confounder effects on anaesthesia vigilance that may explain some of the results, particularly as arising from observational, non-randomised, non-blinded research.
Be careful
The challenge for cognitive aid research is that commonly it must use surrogate markers (workflow step failure; behavioural deviations; efficiency; time spent on task etc.) rather than the safety outcomes that actually matter to patients: death and injury.
There is no easy way around this other than large multi-center studies focusing on outcomes, such as the WHO surgical safety checklist study – which even then, has not escaped criticism!
Thinking deeper...
There will continue to be tension between those pro-checklist and those against. The irony is that both camps share a similar rationale for their position: the advocates for routine checklists point to the safety benefits of reducing cognitive load, whereas those opposing argue that enforced use is anti-individual and itself adds additional task and cognitive burden for clinicians.
Daniel Jolley
Why is this significant?
This is the first randomised controlled trial looking at the impact of perioperative ketamine on persistent post-surgical (PPS) pain 1 year after thoracic surgery. Thoracotomy is associated with both severe and a high incidence (up to 50% at 6 months) chronic pain.
Ketamine has important analgesic properties through NMDA blockade, and has been long thought (hoped) that via this it may modify chronic post-surgical pain. Nonetheless, many studies have been unable to show a benefit for ketamine in reducing PPS pain.
What did they show?
Chumbley et al. ran ketamine infusions at 0.1 mg/kg/hour for 96 hours in patients undergoing thoracotomy, starting with a 0.1 mg/kg bolus 10 minutes before surgery. Patients also received either an epidural or paravertebral infusion for post-operative analgesia.
Although there were small differences in acute pain (notably the ketamine group used less PCA morphine) there was no difference in persistent post-surgical pain at 12 months.
Bottom-line
The evidence continues to mount against perioperative ketamine, suggesting it does not reduce persistent post-surgical pain, not-withstanding its acute analgesia benefits. Await results of the ROCKet trial (Reduction Of Chronic Post-surgical Pain with Ketamine) to provide greater clarity...
An afterthought
Notably, the researchers did demonstrate a dramatically lower incidence of PPS pain than for similar studies (27%, 18%, 13% at 3, 6, 12 months) across both the ketamine and placebo group. This suggests that either the study participants were not representative of the typical thoracotomy patient (unlikely), or other care associated with the study had a beneficial effect on reducing PPS – perhaps even via a Hawthorne-like effect.
Daniel Jolley
The importance...
The growth in procedural medicine has seen increasing numbers of older patients undergoing surgery, with significant concern for the unproven potential of surgery and anaesthesia to hasten cognitive decline. Perioperative stroke is a major adverse event with high mortality (32%) and morbidity (59%) with cognitive consequences.
The NeuroVISION investigators sought to quantify the burden of covert stroke, that is stroke without overt symptoms.
What did they do?
The researchers conducted a multi-center prospective cohort study of 1,114 patients ≥65 years having elective non-cardiac, non-intracranial, non-carotid surgery. All patients underwent post-operative MRI to identify cerebral infarction, and 1 year follow-up to quantify cognitive decline.
And they found?
7% of patients showed MRI features of covert stroke. Of these 42% demonstrated cognitive decline at 1 year, compared to 29% of those without covert stroke (OR CI 1.22-3.20). There were associations with delirium (HR CI 1.06-4.73) and symptomatic stroke or TIA (HR CI 1.14-14.99).
Thus covert stroke is relatively common in this cohort of patients, and is associated with cognitive decline. Notably there was no associated increase in non-neurological outcomes or death, nor association with anaesthetic technique.
Hang on...
Although covert stroke was associated with greater incidence of cognitive decline, the later was still common among non-stroke patients (almost 30%), and around 25% of all patients showed MRI evidence of old chronic infarcts. Additionally because there was no non-surgical control, it is difficult to implicate surgery and anaesthesia itself as a precipitant of the covert strokes (compared with the disease process requiring surgery, or comorbidity).
Perhaps the greater take-home is that in an elderly population with significant morbidity (64% HT, 44% smokers, 27% DM) both stroke (chronic, covert and overt) and cognitive decline are not uncommon.
And the big question
Are any of these stroke related outcomes actually modifiable perioperatively? To meaningfully improve perioperative outcomes, there must be an available improvement in anaesthetic technique, surgical technique or triaging, or postoperative care.
It is likely that the greatest impact is still to be made through primary health care and not perioperative interventions.
Daniel Jolley
What did they do?
The researchers randomised 130 women to 10 mg intrathecal hyperbaric bupivacaine plus an ultrasound-guided TAP block, or to 10mg intrathecal hyperbaric bupivacaine with 100 mcg morphine, plus a sham TAP block.
And they found
There was no difference between either group for satisfaction, analgesia or adverse effects. They concluded that in the context of intrathecal morphine availability, there is no benefit from TAP block, although TAP block can produce comparable analgesia if IT morphine is not used.
What’s particularly interesting...
Unlike the majority of obstetric anaesthesia research, this study comes from the same environment that also manages the bulk of global deliveries: low and medium income countries.
It is also an important reminder that not only are techniques used in wealthier countries applicable and translatable to lower-resource settings, but so is high quality research – and as with all research, context is everything.
Daniel Jolley
Why is this important?
The numerous benefits of neuraxial anesthesia (spinal, epidural, combined spinal-epidural) versus general anesthesia for cesarean section are well established.
While maternal and emergent risks for general anesthesia are well known (ethnic groups; emergencies; maternal disease), Cobb et al. present the highest quality evidence to date showing obstetric anesthesia specialization is associated with a lower GA rate.
What did they do?
The researchers conducted a retrospective cohort study at a large metropolitan teaching hospital (Philadelphia, Pennsylvania) over a 4 year period, comparing general anesthesia versus neuraxial, and obstetric-specialized1 vs generalist anesthesiologists for 4,217 singleton CS deliveries.
And they found?
The total study GA rate was 9.0%. Two-thirds of CS anesthesia was provided by seven specialist obstetric anesthesiologists, versus one-third provided by 33 generalists.
Specialist obstetric anesthesiologists demonstrated a significantly lower GA rate, 7.3% vs 12.1% (OR-CI 0.45-0.79). This difference persisted for the urgent/emergent CS sub-group, though not for after-hours delivery.
Nonetheless several non-provider factors were more strongly associated with GA such as emergency CS (⇡ 7-fold), maternal medical indications for CS (⇡ 3-fold), and after-hours CS (⇡ OR 33%).
Thus care by a specialist obstetric anesthesiologist is associated with an almost-30% reduction in GA for CS .
"...consider selecting neuraxial techniques in preference to general anesthesia for most cesarean deliveries." - ASA obstetric anesthesia task force. 2
Between the lines...
The individual obstetric-specialized anesthesiologists in this study had an almost 10-fold greater cesarean case load than did the average generalist. Whether the outcome difference was due to technical expertise, decision making or a combination, one message here is that you get better at what you do when you intentionally do more of it.
Daniel Jolley
Why is this important?
Post-operative fatigue (POF) is common and has significant effects on post-operative recovery and quality of life.
Past studies have linked post-operative fatigue to the pro-inflammatory effects of surgery and anesthesia. Other studies have suggested anti-inflammatory benefits of steroids, tight glucose control and avoiding deep anesthesia.
What did they do?
Abdelmalak and team randomized 381 patients using a 3-factorial design for the three interventions. 306 patients were analysed for POF outcome.
Surgical interventions covered a wide range of major non-cardiac procedures, with mean surgical length just under 5 hours and 75% of patients being ASA 3 or 4.
And they found?
No difference for any of the interventions for either fatigue or quality of life.
Hang on...
While it may be that post-operative inflammation is not the causative factor for POF, more likely the study interventions had insufficient impact on inflammation to change fatigue outcomes.
For minor and moderate surgery of shorter duration in lower-acuity patients (ASA 1 & 2) who have experienced significant POF previously, these simple interventions may still be beneficial.
Daniel Jolley
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.
They note...
Be smart
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.
Daniel Jolley