Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2019
Meta AnalysisKetamine Infusions for Chronic Pain: A Systematic Review and Meta-analysis of Randomized Controlled Trials.
Why?
Although often used to manage chronic pain acutely, the longer-term benefits of ketamine infusions remain uncertain. Despite this there has been significant growth in using ketamine infusions to treat chronic pain, rationalised by ketamine’s expected effect to reduce central sensitisation.
What?
This meta-analysis identified a small benefit for up to two weeks after a ketamine infusion, although little evidence of longer-term benefit. There appears to be a dose-response effect, suggesting greater efficacy with high-dose ketamine infusions.
The underlying problem...
Most research on ketamine infusions focuses on perioperative analgesia. Trials invetsigating ketamine infusions for chronic pain are universally small, lack standardisation and are often low quality.
This meta-analysis unfortunately does not add clarity to the question of whether ketamine infusions have long-term benefit in chronic pain syndromes. Clinicians will continue to need to judge indication on a case-by-case basis...
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Anesthesia and analgesia · Jul 2019
ReviewSafety of Beach Chair Position Shoulder Surgery: A Review of the Current Literature.
Although uncommon, severe neurological events have been reported in patients undergoing shoulder surgery in the beach chair position. The presumed etiology of central nervous system injury is hypotension and subsequent cerebral hypoperfusion that occurs after alterations in positioning under general anesthesia. Most clinical trials have demonstrated that beach chair positioning results in reductions in regional brain oxygenation, cerebral blood flow, and jugular bulb oxygenation, as well as impairment in cerebral autoregulation and electroencephalographic/processed electroencephalographic variables. Further studies are needed to define the incidence of adverse neurological adverse events in the beach chair position, identify the best intraoperative neurological monitors that are predictive of neurocognitive outcomes, the lowest "safe" acceptable blood pressure during surgery for individual patients, and the optimal interventions to treat intraoperative hypotension.
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Anesthesia and analgesia · Jul 2019
Randomized Controlled TrialRemote Ischemic Preconditioning Prevents Postoperative Acute Kidney Injury After Open Total Aortic Arch Replacement: A Double-Blind, Randomized, Sham-Controlled Trial.
Why the fuss?
Acute renal injury is a common post-operative complication among high-risk patients and after major surgery, particularly cardiac and major vascular surgery, as is relevant to this study. The clinical relevance of ischaemic preconditioning continues to be controversial.
Even mild post-operative acute kidney injury (AKI) is associated with a wide range of poor perioperative outcomes, and current interventions have struggled to reduce such risk.
What is remote ischaemic preconditioning (RIPC)?
In an effort to protect an at-risk end organ from ischaemia (eg. heart, brain, kidneys), RIPC cyclically induces ischaemia in a remote site (typically an arm using an NIBP cuff). This activates physiological protective mechanisms against hypoxia and reperfusion injury in the target organ. It is cheap, easy and safe.
RIPC as a technique is based upon Murray’s 1986 observations of dog LAD arteries.
Although remote ischaemic (pre)conditioning has been demonstrated in animal models, human studies have been contradictory.
What was done...
This Shanghai research team randomised 130 patients undergoing open aortic arch replacement to receive either remote ischaemic preconditioning (4x 5-min-up 5-min-down) or sham preconditioning.
They found...
Fewer patients demonstrated renal injury at 7 days in the treatment group (55% vs 74%, ARR 95% CI 2-35%), in addition to shortening mechanical ventilation duration (18 vs 25 hours).
Practice changing? No
Although this study has shown a marked reduction in AKI in a uniquely very-high-risk group, as a sole small single-centered study it can barely be applied to the actual study population, let alone generalised to other high-risk groups.
Even when AKI in the control group was a massive 74%, the confidence interval for absolute risk reduction (2-35%) is so wide as to cast doubt on the credibility of this result.
Go deeper:
Meybohm (NEJM 2015), Hausenloy (NEJM 2015), and Menting (Cochrane 2017) failed to show any significant renoprotective effect from RIC in other high-risk groups.
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Anesthesia and analgesia · Jul 2019
Use of Hydroxocobalamin (Vitamin B12a) in Patients With Vasopressor Refractory Hypotension After Cardiopulmonary Bypass: A Case Series.
Vitamin B12a (hydroxocobalamin) may be beneficial in managing vasoplegic syndrome following cardiopulmonary bypass.
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Anesthesia and analgesia · Jul 2019
ReviewEvidence Review Conducted for the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery: Focus on Anesthesiology for Bariatric Surgery.
Why is this important?
With obesity rates over 40% in many industrialised countries, and accelerating growth in bariatric surgery for more than a decade, there is need for evidence based guidelines to direct perioperative care.
This evidence review was conducted to identify protocols that achieve "superior outcomes, reduced length of hospital stay, and cost savings" for bariatric patients.
Many of the institutional protocols were founded on ERAS principals originating with colorectal surgery.
Ok, what did they identify?
The AHRQ made evidence-based anesthesia recommendations across three areas:
- Preoperative: reduce fasting; provide carbohydrate loading; multimodal preanesthesia medication.
- Intraoperative: standardised intraoperative anesthesia; protective ventilation; goal-directed fluid therapy (minimization); postop nausea and vomiting prophylaxis.
- Postoperative: multimodal analgesia.
Reality check
These protocols largely reflect 'good quality modern anesthesia', and there is little here that is specific to bariatric patients.
This is not a critcism, but a reminder that it's consistent and holistic application of quality anesthesia across the perioperative period that improves outcomes – especially among higher risk patients. Interventions do not need to be fancy, just quality principles consistently applied.
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