The rationale for perioperative brain protection:

Dextrose 50% versus Dextrose 10% or Dextrose Titration for the Treatment of Out-of-Hospital Hypoglycemia: A Systematic Review

INTRODUCTION

Paramedics commonly administer intravenous (IV) dextrose to severely hypoglycemic patients. Typically, the treatment provided is a 25g ampule of 50% dextrose (D50). This dose of D50 is meant to ensure a return to consciousness. However, this dose may cause harm and lead to difficulties regulating blood glucose levels (BGLs) post-treatment. It is hypothesized that a lower concentration, such as 10% dextrose (D10), may improve symptoms while minimizing harm.

METHODS

PubMed, Embase, CINAHL, and Cochrane Central were systematically searched on September 15, 2020. The PRISMA guidelines were followed. GRADE and risk of bias were applied to determine the certainty of the evidence. Primary literature investigating the use of IV dextrose in hypoglycemic diabetic patients presenting to paramedics or the emergency department was included. Outcomes of interest included safety, efficacy (symptom resolution), and BGL.

RESULTS

Of 680 abstracts screened, 51 full-text articles were reviewed, with eleven studies included. Data from three randomized controlled trials (RCTs) and eight observational studies were analyzed. A single RCT comparing D10 to D50 was identified. The primary significant finding of the study was an increased post-treatment glycemic profile by 3.2mmol/L in the D50 group; no other outcomes had significant differences between groups. When comparing pooled data from all the included studies, there was greater symptom resolution in the D10 group (95.9%) compared to the D50 group (88.8%). However, the mean time to resolution was approximately four minutes longer in the D10 group (4.1 minutes [D50] versus 8.0 minutes [D10]). There was a greater need for subsequent doses with the use of D10 (19.5%) compared to D50 (8.1%). The post-treatment glycemic profile was lower in the D10 group at 6.2mmol/L versus 8.5mmol/L in the D50 group. Both treatments had nearly complete resolution of hypoglycemia: 98.7% (D50) and 99.2% (D10). No adverse events were observed in the D10 group (0/1057) compared to 13/310 adverse events in the D50 group.

CONCLUSION

Studies show D10 may be as effective as D50 at resolving symptoms and correcting hypoglycemia. Although the desired effect can take several minutes longer, there appear to be fewer adverse events. The post-D10-treatment BGL may result in fewer untoward hyperglycemic episodes.

Protecting the brain during neurosurgical procedures: strategies that can work

PURPOSE OF REVIEW

The quest for neuroprotection strategies during periods of neuronal vulnerability persists despite decades of basic and clinical research. This review will focus on the latest developments in the area of clinical brain protection with the major emphasis on strategies that can be beneficial during neurosurgical procedures.

RECENT FINDINGS

Brain protection in neurosurgical patients may be achieved by nonpharmacological and pharmacological strategies. Pharmacological neuroprotection including anaesthetic administration have not been recently shown to be successful. Alternatively, nonpharmacological strategies including maintenance of cerebral perfusion by adequate control of mean arterial pressure (≥80 mmHg), liberal normoglycaemia (7.8-10 mmol/l), adequate haemoglobin levels (preoperative ≥120 g/l and intraoperative ≥90 g/l) and induction of hypertension (20-40% of preoperative values) in certain neurosurgical situations can be beneficial as neuroprotectants during neurosurgery. Mild hypothermia (32-35°C) failed to achieve neuroprotective effects in several situations of brain injury.

SUMMARY

The findings of this review suggest that the anaesthesiologist is compelled to use nonpharmacological strategies sometimes based on empiric evidence to protect the brain during neurosurgical procedures. These strategies are simple, have high benefit/risk ratios and are inexpensive. Rigorous controlled clinical studies are needed to investigate the neuroprotective efficacy of these commonly used nonpharmacological methods.

Inhalational anesthetics as neuroprotectants or chemical preconditioning agents in ischemic brain

This review will focus on inhalational anesthetic neuroprotection during cerebral ischemia and inhalational anesthetic preconditioning before ischemic brain injury. The limitations and challenges of past and current research in this area will be addressed before reviewing experimental and clinical studies evaluating the effects of inhalational anesthetics before and during cerebral ischemia. Mechanisms underlying volatile anesthetic neuroprotection and preconditioning will also be examined. Lastly, future directions for inhalational anesthetics and ischemic brain injury will be briefly discussed.

Anesthetic Preconditioning with Sevoflurane Does Not Protect the Spinal Cord After an Ischemic-Reperfusion Injury in the Rat

Anesthetic preconditioning (APC) is a protective mechanism, whereby exposure to a volatile anesthetic renders a tissue resistant to a subsequent ischemic insult. We hypothesized that APC of the rat spinal cord with sevoflurane would reduce neurologic deficit after an ischemic-reperfusion injury. Rats were randomly assigned to 1 of 5 groups. The ischemic preconditioning (IPC) group (n = 14) had 3 min of IPC, 30 min of reperfusion, and 12 min of ischemia. The chronic APC (cSEVO) group (n = 14) had 1 h of APC with 3.5% sevoflurane on each of 2 days before ischemia. The acute APC (aSEVO) group (n = 14) had 1 h of APC with 3.5% sevoflurane followed by a 1-h washout period before the induction of ischemia. The controls (n = 14) underwent no preconditioning before ischemia. IPC attenuated the ischemia-reperfusion injury, whereas aSEVO and cSEVO groups were no better than control animals. Histologic evaluation of the spinal cord showed severe neurologic damage in all groups except for the IPC group and sham-operated rats. APC with sevoflurane did not reduce neurologic injury in a rat model of spinal cord ischemia. Traditional ischemic preconditioning had a strong protective benefit on neurologic outcome.