Anesthesia Management

Dural Sac Extent in Neonatal Caudal Block

An anatomic study in neonates sought to determine how close the dural sac was to the apex of the sacral hiatus, as this may lead to unintended spinal injection. Average distance in males was 10.9mm and 9.6mm in females; it increased with greater neonate length. Range was 4.9 -26.3mm.

“Anesthesiologists should be aware of the short distance between the sacral hiatus and the dural sac when performing caudal blocks, the shortest distance was 4.94 mm. Armed with this knowledge, caudal techniques should be modified to improve the safety and reduce the risk of complications, such as dural puncture.”

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Crystalloids vs. Colloids in Surgical Hypovolemia

Immense concern has existed regarding the evidence that colloids, in particular starches, increase mortality and renal injury, especially in septic shock. A previous study in critical care however found no mortality difference ( link ). The present subgroup analysis was focussed on critically ill surgical hypovolemic shock needing surgery before or within 24 hours of ICU admission. Again, no difference in mortality or renal injury was found.

Nuances like differentiation between synthetic colloids and albumin, and potential benefits of balanced salt solutions were not addressed so once again, the debate will continue. In particular the results should not at this point be extrapolated to the different population of septic shock patients.

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Gastric Volume/Content in Elective Pediatric Surgery

This prospective cohort study aimed to identify “at risk” stomachs – with solid content or more than 1.25ml/kg in elective pediatric surgery. Median duration of fasting was 4 hours for liquids and >13 hours for solids. They found only 1% of elective children had potentially increased risk for pulmonary aspiration, but none had solid contents

While the overall findings are reassuring, they also draw attention to the often prolonged fasting times in pediatric surgery.

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Sleep Apnea and Peri-operative Oitcomes

Obstructive Sleep Apnea is a red flag for surgery and anesthesia and ASA guidelines exist to identify and manage it peri-operatively, based on factors such as its severity, type/magnitude of surgery and need for postoperative opioids. The present study, although based on administrative data, is noteworthy as it involved a common ambulatory procedure, shoulder arthroscopy.

There was an increased risk of pulmonary complications, myocardial infarction, and an increased odds of requiring postoperative ventilation, hospital admission, and intensive care unit admission. These are significant for an ambulatory procedure and emphasize the need for caution in this population.

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Catheter-Over-Needle in Regional Anesthesia

A comparison was made between peripheral nerve blockade using catheter-through-needle and catheter-over-needle systems. There was no difference in analgesia or local anesthetic leakage, and the overall low rate of leakage was noteworthy. The catheter-over-needle system may have advantages in terms of speed of use and rate of inadvertent catheter dislodgement, but was associated with lower needle visibility on ultrasound.

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Intra-Operative Transfusion Guidelines

Electronic decision support tools as well as education may be necessary to encourage physicians to adopt best practices, as discussed in this article on “hemovigilance”. Newly qualified staff are more likely to adopt these practices as compared with attending physicians.

By and large the evidence is supportive of a restrictive blood transfusion policy with a Hemoglobin of 7g/dl as a target in hemodynamically stable patients. Some studies have led the AABB (formerly known as the American Association of Blood Banks) to use 8g/dl as a threshold in cardiac and orthopedic surgery as well as those with pre-existing cardiovascular disease.

The authors worryingly note: “One study found that 9.2% of intraoperative transfusions failed to meet a physiological indication (mean arterial pressure or heart rate) or a hemoglobin threshold <10 g/d”.

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Transversus Abdominis Plane Block in Children

“In children, quality of postoperative pain control provided by transversus abdominis plane (TAP) block using levobupivacaine 0.4 mg·kg−1 administered as either 0.2% or 0.4% did not differ and was associated with a very low risk of local anesthetic systemic toxicity”. The study involved inguinal day surgery and about 70% did not require any postoperative opioids. However the study only compared the two concentrations, there being no comparison with a control group not given the TAP block.

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Sugammadex Effectiveness in Elderly

Sugammadex was tested tested in elderly patients for reversing deep Rocuronium induced neuromuscular block. Increasingly seen as s faster and more complete agent compared to Neostigmine, this study found that low (as well as common clinical doses) were not as fast or effective in the elderly, and residual blockade and recurarization were more common. Renal function and obesity were risk factors also. The study highlights the need again for universal neuromuscular monitoring in all patients, even when Sugammadex is used.

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Peripheral nerve blockade in diabetic neuropathy

This study found that after ultrasound‐guided popliteal sciatic nerve block, patients with diabetic peripheral neuropathy had a reduced time to onset of sensory blockade, with increased time to first opioid request when compared with patients without neuropathy. 30 ml 1:1 mixture of lidocaine 1% and bupivacaine 0.5% was used

Concern has existed that patients with peripheral neuropathy have increased sensitivity as well as nerve injury risk from local anesthetics. The “double crush” hypothesis of already ischemic/hypoxia nerves suffering more injury from needles or local anesthesia has been a concern although not totally proven; this study was not powered to make such a conclusion. However, it may guide dose selection for peripheral nerve blocks in this population.

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