Pharmacology

SGLT Inhibitors and Diabetic Ketoacidosis

The popularity of SGLT Inhibitors has increased with purported cardiovascular and renal benefits. Issues have arisen however and this consensus addresses the reported cases of normoglycemic diabetic ketoacidosis.

Pertinent to perioperative care, “SGLT inhibitors should be withheld or discontinued prior to any medical procedure (ideally for 3 days), particularly if the patient will be reducing food intake or will not be allowed to eat or drink for some time before and after the procedure.”

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Tramadol and Persistent Opioid Use

Faced with the opioid epidemic, many have turned to postoperative use of Tramadol in the belief it has less misuse potential.

This observational study finds however that: “People receiving tramadol alone after surgery had similar to somewhat higher risks of prolonged opioid use compared with those receiving other short acting opioids”.

They advocate reclassifying Tramadol and urge caution in its prescription.

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Intraoperative Seizures During Elective Craniotomy

This retrospective study found that the incidence of intraoperative seizures during elective craniotomy with evoked potential monitoring is low. 

The overall incidence of intraoperative seizures was 2.3%. Independent risk factors for intraoperative seizures were seizure history, diagnosis of intracranial tumor, and temporal craniotomy. 

Intraoperative prophylactic anticonvulsant use was protective.

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Opioid Sparing in Pediatric Adenotonsillectomy

This QI project identified an opioid sparing anesthesia approach for pediatric tonsillectomy and adenotonsillectomy that moved away from morphine and acetaminophen, though Dexmedetomidine plus Ibuprofen, and finally on to the most effective regime consisting of Dexmedetomidine plus Ketorolac.

The study highlights both the move away from opioid based anesthesia as well as the increasing use of Intraoperative Dexmedetomidine.

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Propofol and Food Allergies

There is some disquiet about using Propofol in those with allergies. This was a retrospective study of children with immunologically confirmed egg, peanut, soybean or legume allergy and who underwent general anaesthesia.

In 9 out of 10 meeting allergic reaction criteria, valid non‐allergic explanations for the clinical symptoms were found.

The authors conclude that genuine serious allergic reaction to propofol is rare and is not reliably predicted by a history of food allergy.

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Intraoperative Methadone

Methadone assisted treatment of substance use disorders is well known but its potential for perioperative analgesia is under appreciated.

This review (full text for ASA members or subscription) may be helpful to introduce it as a long lasting intravenous agent given at the beginning of surgery. Common doses are 0.1 – 0.3mg/kg or a single 20mg dose with 3 – 5mg in PACU q 20mins. Analgesia is generally quite prolonged for 24 hours or more, and most of the evidence provided here does not show a higher rate of respiratory depression.

Caution is advised in the elderly or morbidly obese or those with cardiovascular co-morbidities. Further studies are needed on its potential adverse effects on QT prolongation or serotonin syndrome, effects on chronic pain, use in ambulatory surgery and in enhanced recovery protocols.

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Dexamethasone IV and Spinal Anesthesia

A systematic literature search followed by conventional meta‐analysis examined the effects of intravenous Dexamethasone during Spinal Anesthesia.

While its effects on nausea and vomiting are well known, this study found a high level of evidence that intravenous dexamethasone improves postoperative analgesia after spinal anaesthesia.

Dexamethasone use was associated with a significant reduction in 24‐h morphine consumption and times to first analgesia request was prolonged by 86 mins.

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Phenylephrine vs. Norepinephrine in Cesarean

A growing interest in the use of small bolus Norepinephrine (Noradrenaline) for Cesarean hypotension is based on its presumed lesser tendency to cause bradycardia compared to Phenylephrine.

This small study compared the effects of 100 μg phenylephrine and 5 μg norepinephrine and found no difference in maternal bradycardia. The number of boluses needed was higher in the Phenylephrine group.

“However, in view of the lower umbilical artery pH when using noradrenaline, further research is warranted to study its placental transfer and fetal metabolic effects”.

Duration and Type of Surgical Prophylaxis and Adverse Events

While retrospective in nature, this study appears to confirm that antibiotic prophylaxis should not be unduly extended after surgery, as complications increase after 24 hours. Higher kidney injury rates occur with Vancomycin also.

Increasing duration of antimicrobial prophylaxis was associated with higher odds of acute kidney injury (AKI) and C difficile infection in a duration-dependent fashion; extended duration did not lead to additional surgical site infection (SSI) reduction. “These findings highlight the notion that every day matters and suggest that stewardship efforts to limit duration of prophylaxis have the potential to reduce adverse events without increasing SSI”.

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Morphine vs. Hydromorphone in Day Surgery

This study objective was to compare morphine with hydromorphone for achieving satisfactory analgesia with minimal emesis in ambulatory surgery.

There were no differences in the side-effects of severe itching, respiratory depression, or sedation. Patient satisfaction, discharge times, and post-discharge outcomes, including pain and nausea/vomiting over 24 h, were also comparable.

It is believed by some that Hydromorphone has more euphoric effects that could encourage substance misuse.

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