Intravenous Acetaminophen & Hip and Kneee Arthroplasty

Intravenous Acetaminophen was hailed as a useful addition to anesthesia care, but almost every study has shown little to be gained compared to oral Acetaminophen.

This latest, albeit a database study in total hip and knee arthroplasty, once again shows no (or less) benefit compared to oral Acetaminophen, which should always where possible be the first choice.

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Acute Pain Trajectories and Remote Pain Resolution

A secondary analysis of the Stanford Accelerated Recovery Trial assessed remote postoperative pain, opioid use, and recovery. The incidence of persistent postsurgical pain ranges from 10% to 50%, and 2% to 10% of patients report severe, chronic pain after surgery.

The study assessed high and low pain clusters in the first 10 days in a mixed surgical cohort. Numerous pain and other scores were administered. The authors identified worst pain over the past 24 hours reported on postoperative day 10 as a significant immediate postoperative predictor of remote pain resolution, opioid cessation, and complete surgical recovery.

The implications are summarized: “Ultimately, early identification of high-risk patients would facilitate personalized care with closer follow-up, earlier referral for specialist care, and extension of multimodal pain regimens”.

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Tramadol and Mortality Among Patients With Osteoarthritis

Tramadol has many drawbacks but is frequently prescribed as a perceived safer agent with less misuse potential.

This cohort study of nearly 89,000 patients aged 50 years and older with osteoarthritis found that initial prescription of tramadol was associated with a significantly higher rate of mortality over 1 year compared with commonly prescribed nonsteroidal anti-inflammatory drugs, but not compared with codeine.

The authors point out the risk of confounding by indication, and further research is needed to determine if this association is causal.

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Lidocaine and Neurologic Outcomes after Cardiac Surgery

50% of cardiac surgery patients leave hospital with cognitive dysfunction which tends to improve but may persist at 5 years in some. Based on previous suggestion that Lidocaine may ameliorate such issues due to postulated anti-inflammatory, blood flow, and cerebral metabolism mechanisms, this randomized study failed to find benefit with use of Lidocaine infusion during and for 48 hours after cardiac surgeries.

Conclusion: Intravenous lidocaine administered during and after cardiac surgery did not reduce postoperative cognitive decline at 6 weeks.

The authors note the complex issues involved in cognitive dysfunction that could not be expected to benefit from a single agents – preoperative cognitive impairment, genetic predisposition, cerebral microembolism or hypoperfusion during CPB, inflammatory responses, hemodilution, hyperglycemia, hyperthermia, unmasking of Alzheimer disease, and acceleration of amyloid deposition associated with inhalational anesthetics.

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Prenatal surgery of fetal open spinal neural tube defects

A full text article describes some of the unique features of anesthesia for prenatal open and fetoscopic surgery of fetal open spinal neural tube defects.

For uterine relaxation, higher MACs of Sevoflurane were used, as well as nitroglycerin and tocolytics. Higher doses as well as greater hemodynamic disturbance occurred with open surgery. Colloids were used more, presumably to lower the risk of pulmonary edema which occurred in 10%, attributable to gestational physiologic changes, tocolytic administration and liberal fluid therapy.

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Neuroanesthesia & Critical Care Guidelines

The Society of Neuroscience in Anesthesiology and Critical Care (SNACC) guidelines and consensus statements are available in full text at the link below.

They encompass guidelines for managing patients at risk of stroke, those with external ventricular/lumbar drains, and anesthetic management of endovascular treatment of acute ischemic stroke.

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Post-Herpetic Neuralgia

An article on post-herpetic neuralgia finds that most patients are still not managed on recommended first line therapies like Lidocaine patches, Gabapentin, Pregabalin, and antidepressants.

Ineffective treatment like NSAIDS are often used, and 22% started on opioids, certainly not a first line recommendation.

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Chewing Gum and Anesthesia

There has been debate about whether patients should be disallowed to chew gum before anesthesia and the risk of aspiration.

This correspondence and cross references suggest that in healthy volunteers gum chewing was not associated with increased gastric fluid volume measured 2 h after the oral intake of 250 ml of water.

Future studies incorporating gastric ultrasound in clinical patients may lead to a more liberal view, and the potential of chewing gum to even improve gastrointestinal recovery in ERAS protocols.

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Perioperative Hypotension and Cardiovascular Events

Another study adds to the now established theme that perioperative hypotension increases cardiovascular events and does so independently of the degree of coronary artery disease.

Hypotension is defined in this study as systolic blood pressure < 90mm Hg for at least 10 mins. Other studies have also used mean arterial pressure < 65.

The nuances show the effects were additive if not multiplicative. There was insufficient evidence that perioperative hypotension may have less deleterious cardiovascular effects in patients with a lesser degree of coronary artery disease compared to greater coronary artery disease.

“These data support efforts for the prevention, monitoring, and treatment of perioperative hypotension regardless of the presence or absence of significant coronary artery disease”.

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Intraoperative Controlled Hypotension and Acute Kidney Injury

This was a retrospective study (immediate caveat!) on total hip arthroplasty under neuraxial anesthesia with intraoperative controlled hypotension (MAP < 60).

Acute kidney injury occurred in 45 (1.85%) of the 2431 patients in this cohort. Longer duration of hypotension was not associated with increased odds of postoperative AKI. Preexisting differences, such as compromised renal function, best predicted increased odds of AKI.

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The authors speculate that inadvertent and controlled hypotension may be different. Hypotension may have surgical benefits but this study should be interpreted with caution in view of the known evidence on the cardiac, renal and mortality associations ( link ).