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. ↩
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