Neuroprotection with anaesthetic agents

Peri-Intubation Hypoxia After Delayed Versus Rapid Sequence Intubation in Critically Injured Patients on Arrival to Trauma Triage: A Randomized Controlled Trial

BACKGROUND

Critically injured patients who are agitated and delirious on arrival do not allow optimal preoxygenation in the emergency area. We investigated whether the administration of intravenous (IV) ketamine 3 minutes before administration of a muscle relaxant is associated with better oxygen saturation levels while intubating these patients.

METHODS

Two hundred critically injured patients who required definitive airway management on arrival were recruited. The subjects were randomized as delayed sequence intubation (group DSI) or rapid sequence intubation (group RSI). In group DSI, patients received a dissociative dose of ketamine followed by 3 minutes of preoxygenation and paralysis using IV succinylcholine for intubation. In group RSI, a 3-minute preoxygenation was performed before induction and paralysis using the same drugs, as described conventionally. The primary outcome was incidence of peri-intubation hypoxia. Secondary outcomes were first-attempt success rate, use of adjuncts, airway injuries, and hemodynamic parameters.

RESULTS

Peri-intubation hypoxia was significantly lower in group DSI (8 [8%]) compared to group RSI (35 [35%]; P = .001). First-attempt success rate was higher in group DSI (83% vs 69%; P = .02). A significant improvement in mean oxygen saturation levels from baseline values was seen in group DSI only. There was no incidence of hemodynamic instability. There was no statistically significant difference in airway-related adverse events.

CONCLUSIONS

DSI appears promising in critically injured trauma patients who do not allow adequate preoxygenation due to agitation and delirium and require definitive airway on arrival.

Changes in anaesthetic use for trauma patients in German HEMS - a retrospective study over a ten-year period

Background

Airway management and use of intravenous anaesthetics to facilitate tracheal intubation after major trauma remains controversial. Numerous agents are available and used for pre-hospital rapid-sequence induction (RSI). The aim was to investigate usage and potential changes in administration of intravenous anaesthetics for pre-hospital RSI in trauma patients over a ten-year period.

Methods

Based on a large helicopter emergency medical service (HEMS) database in Germany between 2006 and 2015, a total of 9720 HEMS missions after major trauma leading to RSI on scene were analysed. Administration practice of sedatives and opioids were investigated, while neuromuscular blocking agents were not documented in the database.

Results

With respect to administration of sedatives, independent from trauma mechanism and specific injury patterns the use of Etomidate decreased dramatically (52 to 6%) in favour of a more frequent use of Propofol (3 to 32%) and Ketamine (9 to 24%; all p < 0.001) from 2006 to 2015. The use of Benzodiazepines increased slightly, while the utilization rate of Barbiturates remained constant. In patients with Shock Index > 1 at initial contact, the administration rate of Etomidate dropped significantly as well. This decline was mainly substituted by Ketamine and particularly Propofol. In patients with GCS ≤ 8 upon initial contact, a similar distribution compared to the general trauma population could be observed.

With respect to opioids, mainly Fentanyl has been administered for RSI in trauma patients (2006: 69,6% to 2015: 60.2%; p < 0.001), while the use of sufentanyl showed a significant increase (0.2 to 8.8%; p < 0.001).

Conclusions

This large study analysed prehospital administration of anaesthetics in trauma patients, showing a substantial change from 2006 to 2015 despite the lack of any high-level evidence. Etomidate has shifted from the main sedative substance to virtual absence, indicating that the recommendation of an established national guideline was transferred into clinical practice, although based on weak evidence as well. The pre-hospital use of Propofol showed a particular increase. Fentanyl has been the main opioid drug for RSI in trauma, however Sufentanyl has become increasingly popular. The mechanisms and advantages of the different substances still have to be elucidated, especially in head injury and bleeding trauma.

Emergency induction of anaesthesia in the prehospital setting: a review of the anaesthetic induction agents

The standard of prehospital care is improving in many trauma systems around the world. For patients surviving the primary injury, the optimal prehospital interven tions remain debatable. Current evidence suggests that patients with severe head injury may benefit from advanced airway management, most commonly per formed by rapid sequence induction of anaesthesia and orotracheal intubation. The ‘best choice’ induction agent remains unclear, and choice seems to depend on local preferences and the skill mix of the prehospital care team. In this review we look at the recent evidence for selected hypnotic agents.

Effects of combined ketamine/xylazine anesthesia on light induced retinal degeneration in rats

Objectives

To explore the effect of ketamine-xylazine anesthesia on light-induced retinal degeneration in rats.

Methods

Rats were anesthetized with ketamine and xylazine (100 and 5 mg, respectively) for 1 h, followed by a recovery phase of 2 h before exposure to 16,000 lux of environmental illumination for 2 h. Functional assessment by electroretinography (ERG) and morphological assessment by in vivo imaging (optical coherence tomography), histology (hematoxylin/eosin staining, TUNEL assay) and immunohistochemistry (GFAP and rhodopsin staining) were performed at baseline (ERG), 36 h, 7 d and 14 d post-treatment. Non-anesthetized animals treated with light damage served as controls.

Results

Ketamine-xylazine pre-treatment preserved retinal function and protected against light-induced retinal degeneration. In vivo retinal imaging demonstrated a significant increase of outer nuclear layer (ONL) thickness in the non-anesthetized group at 36 h (p<0.01) and significant reduction one week (p<0.01) after light damage. In contrast, ketamine-xylazine pre-treated animals showed no significant alteration of total retinal or ONL thickness at either time point (p>0.05), indicating a stabilizing and/or protective effect with regard to phototoxicity. Histology confirmed light-induced photoreceptor cell death and Müller cells gliosis in non-anesthetized rats, especially in the superior hemiretina, while ketamine-xylazine treated rats showed reduced photoreceptor cell death (TUNEL staining: p<0.001 after 7 d), thicker ONL and longer IS/OS. Fourteen days after light damage, a reduction of standard flash induced a-wave amplitudes and a-wave slopes (p = 0.01) and significant alterations in parameters of the scotopic sensitivity function (e.g. Vmax of the Naka Rushton fit p = 0.03) were observed in non-treated vs. ketamine-xylazine treated animals.

Conclusions

Our results suggest that pre-treatment with ketamine-xylazine anesthesia protects retinas against light damage, reducing photoreceptor cell death. These data support the notion that anesthesia with ketamine-xylazine provides neuroprotective effects in light-induced cell damage.