Xenon as an adjuvant to sevoflurane anesthesia in children younger than 4 years of age, undergoing interventional or diagnostic cardiac catheterization: A randomized controlled clinical trial

Effects of xenon anesthesia on postoperative neurocognitive disorders: a systematic review and meta-analysis

The latest clinical trials have reported conflicting outcomes regarding the effectiveness of xenon anesthesia in preventing postoperative neurocognitive dysfunction; thus, this study assessed the existing evidence. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases from inception to April 9, 2023, for randomized controlled trials of xenon anesthesia in postoperative patients. We included English-language randomized controlled studies of adult patients undergoing surgery with xenon anesthesia that compared its effects to those of other anesthetics. Duplicate studies, pediatric studies, and ongoing clinical trials were excluded. Nine studies with 754 participants were identified. A forest plot revealed that the incidence of postoperative neurocognitive dysfunction did not differ between the xenon anesthesia and control groups (P = 0.43). Additionally, xenon anesthesia significantly shortened the emergence time for time to opening eyes (P < 0.001), time to extubation (P < 0.001), time to react on demand (P = 0.01), and time to time and spatial orientation (P = 0.04). However, the Aldrete score significantly increased with xenon anesthesia (P = 0.005). Postoperative complications did not differ between the anesthesia groups. Egger's test for bias showed no small-study effect, and a trim-and-fill analysis showed no apparent publication bias. In conclusion, xenon anesthesia probably did not affect the occurrence of postoperative neurocognitive dysfunction. However, xenon anesthesia may effectively shorten the emergence time of certain parameters without adverse effects.

Novel anesthetics in pediatric practice: is it time?

PURPOSE OF REVIEW

Steadily mounting evidence of anesthesia-induced developmental neurotoxicity has been a challenge in pediatric anesthesiology. Considering that presently used anesthetics have, in different animal models, been shown to cause lasting behavioral impairments when administered at the peak of brain development, the nagging question, 'Is it time for the development of a new anesthetic' must be pondered.

RECENT FINDINGS

The emerging 'soft analogs' of intravenous anesthetics aim to overcome the shortcomings of currently available clinical drugs. Remimazolam, a novel ester-analog of midazolam, is a well tolerated intravenous drug with beneficial pharmacological properties. Two novel etomidate analogs currently in development are causing less adrenocortical suppression while maintaining equally favorable hemodynamic stability and rapid metabolism. Quaternary lidocaine derivatives are explored as more potent and longer lasting alternatives to currently available local anesthetics. Xenon, a noble gas with anesthetic properties, is being considered as an anesthetic-sparing adjuvant in pediatric population. Finally, alphaxalone is being reevaluated in a new drug formulation because of its favorable pharmacological properties.

SUMMARY

Although a number of exciting anesthetic drugs are under development, there is currently no clear evidence to suggest their lack of neurotoxic properties in young brain. Well designed preclinical studies are needed to evaluate their neurotoxic potential.

Do We Have Viable Protective Strategies against Anesthesia-Induced Developmental Neurotoxicity?

Since its invention, general anesthesia has been an indispensable component of modern surgery. While traditionally considered safe and beneficial in many pathological settings, hundreds of preclinical studies in various animal species have raised concerns about the detrimental and long-lasting consequences that general anesthetics may cause to the developing brain. Clinical evidence of anesthetic neurotoxicity in humans continues to mount as we continue to contemplate how to move forward. Notwithstanding the alarming evidence, millions of children are being anesthetized each year, setting the stage for substantial healthcare burdens in the future. Hence, furthering our knowledge of the molecular underpinnings of anesthesia-induced developmental neurotoxicity is crucially important and should enable us to develop protective strategies so that currently available general anesthetics could be safely used during critical stages of brain development. In this mini-review, we provide a summary of select strategies with primary focus on the mechanisms of neuroprotection and potential for clinical applicability. First, we summarize a diverse group of chemicals with the emphasis on intracellular targets and signal-transduction pathways. We then discuss epigenetic and transgenerational effects of general anesthetics and potential remedies, and also anesthesia-sparing or anesthesia-delaying approaches. Finally, we present evidence of a novel class of anesthetics with a distinct mechanism of action and a promising safety profile.

Effect of xenon and dexmedetomidine as adjuncts for general anesthesia on postoperative emergence delirium after elective cardiac catheterization in children: study protocol for a randomized, controlled, pilot trial

Background

Emergence delirium, a manifestation of acute postoperative brain dysfunction, is frequently observed after pediatric anesthesia and has been associated with the use of sevoflurane. Both xenon and dexmedetomidine possess numerous desirable properties for the anesthesia of children with congenital heart disease, including hemodynamic stability, lack of neurotoxicity, and a reduced incidence of emergence delirium. Combining both drugs has never been studied as a balanced-anesthesia technique. This combination allows the provision of anesthesia without administering anesthetic drugs against which the Food and Drug Administration (FDA) issued a warning for the use in young children.

Methods/Design

In this phase-II, mono-center, prospective, single-blinded, randomized, controlled pilot trial, we will include a total of 80 children aged 0–3 years suffering from congenital heart disease and undergoing general anesthesia for elective diagnostic and/or interventional cardiac catheterization. Patients are randomized into two study groups, receiving either a combination of xenon and dexmedetomidine or mono-anesthesia with sevoflurane for the maintenance of anesthesia.

The purpose of this study is to estimate the effect size for xenon-dexmedetomidine versus sevoflurane anesthesia with respect to the incidence of emergence delirium in children. We will also describe group differences for a variety of secondary outcome parameters including peri-interventional hemodynamics, emergence characteristics, incidence of postoperative vomiting, and the feasibility of a combined xenon-dexmedetomidine anesthesia in children.

Discussion

Sevoflurane is the most frequently used anesthetic in young children, but has been indicated as an independent risk factor in the development of emergence delirium. Xenon and dexmedetomidine have both been associated with a reduction in the incidence of emergence delirium. Combining xenon and dexmedetomidine has never been described as a balanced-anesthesia technique in children. Our pilot study will therefore deliver important data required for future prospective clinical trials.

Trial registration

EudraCT, 2018–002258-56. Registered on 20 August 2018. https://www.clinicaltrialsregister.eu.

Update of the organoprotective properties of xenon and argon: from bench to beside

The growth of the elderly population has led to an increase in patients with myocardial infarction and stroke (Wajngarten and Silva, Eur Cardiol 14: 111–115, 2019). Patients receiving treatment for ST-segment-elevation myocardial infarction (STEMI) highly profit from early reperfusion therapy under 3 h from the onset of symptoms. However, mortality from STEMI remains high due to the increase in age and comorbidities (Menees et al., N Engl J Med 369: 901–909, 2013). These factors also account for patients with acute ischaemic stroke. Reperfusion therapy has been established as the gold standard within the first 4 to 5 h after onset of symptoms (Powers et al., Stroke 49: e46-e110, 2018). Nonetheless, not all patients are eligible for reperfusion therapy. The same is true for traumatic brain injury patients. Due to the complexity of acute myocardial and central nervous injury (CNS), finding organ protective substances to improve the function of remote myocardium and the ischaemic penumbra of the brain is urgent. This narrative review focuses on the noble gases argon and xenon and their possible cardiac, renal and neuroprotectant properties in the elderly high-risk (surgical) population. The article will provide an overview of the latest experimental and clinical studies. It is beyond the scope of this review to give a detailed summary of the mechanistic understanding of organ protection by xenon and argon.

The effect of xenon-augmented sevoflurane anesthesia on intraoperative hemodynamics and early postoperative neurocognitive function in children undergoing cardiac catheterization: A randomized controlled pilot trial

BACKGROUND

In adults, xenon has only minimal hemodynamic side effects when compared with other anesthetics. Moreover, in preclinical experiments, xenon has been demonstrated to possess cardio- and neuroprotective properties. Altogether, the favorable hemodynamic profile combined with its potential for organ-protection could render xenon an attractive option for anesthesia in children with cardiovascular compromise.

AIMS

The aim of this study was to explore safety and feasibility of sevoflurane-augmented xenon anesthesia in school-aged children and to assess early postoperative neurocognitive effects of xenon-sevoflurane and sevoflurane anesthesia when compared to a control group that did not have anesthesia.

METHODS

Forty children aged 4-12 years, suffering from congenital heart disease, undergoing diagnostic or interventional cardiac catheterization were randomized to either xenon-augmented sevoflurane anesthesia or sevoflurane alone. Safety was assessed by the incidence of intraprocedural hemodynamic instability and feasibility by anesthetic depth and respiratory profile. In addition, neurocognitive performance was assessed preoperatively, 2 hours after discharge from PACU and at 24 hours after anesthesia using the Amsterdam Neuropsychological Tasks system. A healthy control group of 22 age- and gender-matched children not exposed to anesthesia underwent an identical neurocognitive test battery, at comparable time intervals.

RESULTS

Overall hemodynamics did not differ between groups. Xenon-sevoflurane anesthesia resulted in decreased intraoperative ephedrine requirements (median [IQR]) (0.00 mg/kg [0.00-0.00] vs 0.00 mg/kg [0.00-0.01], P = 0.047). Only neurocognitive tests in the domain of alertness were significantly impaired 2 hours postoperatively in both anesthesia groups in comparison with the control group (alertness variability: P = 0.02, odds ratio 5.8), but recovered at 24 hours. For working memory, inhibition, cognitive flexibility, and motor coordination tasks, no significant interaction effects of anesthesia were found in the early postoperative period.

CONCLUSION

In this pilot trial, xenon-augmented sevoflurane anesthesia in school-aged children was feasible, and associated with decreased ephedrine requirements. All children exposed to anesthesia showed impaired neurocognitive performance in the immediate postoperative period when compared to control children; however, without significant differences between both treatment groups.

Neurologic and cognitive outcomes associated with the clinical use of xenon: a systematic review and meta-analysis of randomized-controlled trials

BACKGROUND

Xenon has been shown to have positive neurologic effects in various pre-clinical models. This study systematically reviewed the randomized-controlled trials (RCTs) investigating neurologic and cognitive outcomes associated with the clinical use of xenon.

METHODS

We searched PubMed, CENTRAL, EMBASE, CINAHL, elibrary.ru (for Russian studies), Google Scholar (for Russian studies), and Wanfang (for Chinese studies) for appropriate RCTs comparing neurologic or cognitive outcomes after clinical use of xenon with control treatment or with other anesthetic agents.

RESULTS

Seventeen RCTs met the inclusion criteria. Two studies investigated the effects of xenon plus therapeutic hypothermia to treat neonatal asphyxia or out-of-hospital cardiac arrest. Compared with therapeutic hypothermia alone, xenon and therapeutic hypothermia reduced cerebral white matter abnormalities after cardiac arrest but had no effect on neurocognitive outcome and mortality. Xenon had no added value when used to treat neonatal asphyxia. Thirteen RCTs compared neurocognitive effects of xenon with other anesthetic agents in surgical patients. While xenon may be associated with improved short-term (< three hours) cognitive outcome, no medium-term (six hours to three months) advantage was observed, and longer-term data are lacking. No differences in biochemical (S-100β, neuron-specific enolase) and neuropsychologic (attentional performance) outcomes were found with xenon compared with other anesthetic drugs. Finally, two studies suggest that brief, intermittent administration of sub-anesthetic doses of xenon to patients during the acute phase of substance withdrawal may improve neurocognitive outcomes.

CONCLUSIONS

Despite promising pre-clinical results, the evidence for positive clinical neurologic and cognitive outcomes associated with xenon administration is modest. Nevertheless, there is some evidence to suggest that xenon may be associated with better neurologic outcomes compared with the standard of care therapy in certain specific clinical situations. More clinical trials are needed to determine any potential benefit linked to xenon administration.