Month: December 2018

Nitrous Oxide and Intra-ocular Gas

Intra-ocular air or various gases are used during vitrectomy, commonly after retinal detachment or macular hole surgery, and also with corneal grafts.

The Royal College of Ophthalmologists has issued a warning about these gases, some of which can persist for 8 weeks (1 week or so for air). The diffusibility of Nitrous Oxide may critically increase intra-ocular pressure if used for analgesia or anesthesia at these times. Patients should also carry warning information after the use of such gas/air.

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Cognitive Effects of Perioperative Pregabalin

Gabapentinoids have been shown in many studies to reduce postoperative pain but side effects such as somnolence, dizziness and even respiratory depression have been also reported (not to mention Gabapentinoid misuse and dependence in longer term use). This secondary analysis adds a further caveat in that Pregabalin may increase the risk of developing impaired postoperative cognitive performance, and this may be more important in older or frail patients.

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POCUS and Blunt Thoracoabdominal Injuries

A Cochrane review urges caution with negative findings from point of care ultrasound (POCUS). While positive findings are helpful, it was found that in blunt abdominal trauma “a negative POCS exam does not rule out injuries and must be verified by a reference test such as CT. This is of particular importance in paediatric trauma, where the sensitivity of POCS is poor”. The now ubiquitous ultrasound in the Emergency Dept. has its limitations!

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Medical and Health News Weekly

Dogs help children having MRIs link

Flu season and children are bearing the brunt link

Thailand legalizes medical cannabis link

Cochrane review: no evidence that any vitamin or mineral supplementation strategy for cognitively healthy adults in mid or late life has a meaningful effect on cognitive decline or dementia link

Opioid poisoning in children and adolescents (largely unintentional) from prescription and illicit drugs is growing alarmingly in the US link

While “breakthroughs” is a fraught term in early research, the BBC summarizes major potential advances in medical science in 2018 link

Succinylcholine Use and Dantrolene Availability

Malignant hypothermia is considered an anaesthesia disease but can also be precipitated by the use of Succinylcholine without volatile anesthesia gas use, as is noted in this analysis.

Succinylcholine is often used to facilitate difficult mask ventilation, and indeed current practice advice is to administer without waiting to check mask ventilation ease.

This study surveyed such cases in the MH registry and other sources documenting 24 cases. They contend Dantrolene should be immediately available in all locations where Succinylcholine (or volatile anesthetics gases) are used as treatment delay is critical.

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Thromboelastometry: new ROTEMsigma

The new generation of ROTEM automates this point of care device for assessing coagulation, relative contributions of clotting factors, fibrinogen, platelets and fibrinolyis. The two technologies of ROTEM and TEG have been studied and early evidence suggests utility in trauma, obstetrics and perhaps in major blood-loss surgeries such as liver or cardiac.

This study found ROTEMsigma exhibited high precision and correlation with previous generation ROTEMdelta devices.

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A review of this point of care coagulation assessment is found here link

IV Iron and Postpartum Anemia

Intravenous iron has become more popular for both preoperative and postoperative anemia as a faster and more efficient alternative to oral iron, with less reactions with modern formulations.

This review and meta-analysis found that hemoglobin concentrations at 6 weeks postpartum were almost 1 g/dL higher in women who received intravenous iron compared to oral iron, with no serious side effects. It lends support to the increasing use of intravenous iron in the obstetric as well as other surgical populations.

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Nerve Block and Injection Pressure

Ultrasound has improved accurate delivery of local anesthetic but often lacks the resolution to avoid intraneural injection, which is generally considered a nerve injury risk (although some have deliberately injected small volumes). Such intraneural injection could be signalled by high injection pressure and in-line devices exist to monitor this pressure.

This study was on silicone and it’s extension to humans remains to be determined. It employed fibreoptic measurement of needle tip pressure and found that such real-time pressure changes were not reflected in in-line measurement, and while more rapid injection may increase in-line pressure, direct needle-tip pressure did not change.

The conclusion is that needle tip pressure measurement is needed rather than the surrogate in-line pressure monitoring.

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