Incidence of emergence agitation in children undergoing sevoflurane anesthesia compared to isoflurane anesthesia: An updated systematic review and meta-analysis.

BACKGROUND: Emergence agitation is a complex syndrome of altered consciousness after emergence from anesthesia. It can result in injury to patients and staff and is associated with other postoperative complications. Sevoflurane has been associated with emergence agitation, potentially due to low tissue solubility and therefore speed of emergence. Prior meta-analyses comparing emergence agitation incidence between sevoflurane and isoflurane anesthetics did not demonstrate a statistically significant difference. Given the publication of additional relevant studies not included in prior meta-analyses as well as improved diagnosis of emergence agitation, we aim to perform an updated, comprehensive meta-analysis comparing emergence agitation incidence between sevoflurane and isoflurane anesthetics in children. METHODS: We conducted an updated systematic review and meta-analysis of clinical trials comparing sevoflurane to isoflurane in children <18 years of age, reporting emergence agitation as an outcome, published before July 2023 using databases and registers. Our primary outcome was the incidence of emergence agitation. Secondary outcomes were time to extubation, awakening time, and length of stay in the postanesthetic care unit. We assessed the risk of bias using the Cochrane Risk of Bias tool version 2. We pooled the effect size for the outcomes using the fixed effects model if we had low heterogeneity, otherwise, we used a random-effects model. RESULTS: Eight randomized controlled trials (523 children) were included in the final analysis. The incidence of emergence agitation after isoflurane was significantly lower compared to sevoflurane (risk ratio: 0.62 (95% CI: [0.46-0.83]; I2 = 40.01%, p < .001)). Time to extubation, awakening times, and postanesthetic care unit duration were not significantly different. The protective effect of isoflurane compared to sevoflurane remained significant in subgroups of patients who received premedication or intraoperative systemic analgesics (risk ratios: (0.48 [0.28-0.82]; I2 = 60.78%, p = .01), (0.52 [0.37-0.75]; I2 = 0.00%, p < .001), respectively). CONCLUSION: The risk of emergence agitation in children after maintenance anesthesia with sevoflurane is significantly greater than with isoflurane; we did not find evidence of prolonged emergence or postanesthetic length of stay. When possible, isoflurane should be considered for maintenance anesthesia over sevoflurane in patients at high risk of emergence agitation.

Tetrodotoxin, Epinephrine, and Chemical Permeation Enhancer Combinations in Peripheral Nerve Blockade.

BACKGROUND: Chemical permeation enhancers (CPEs) have the potential to improve nerve blockade by site 1 sodium channel blockers such as tetrodotoxin (TTX). Here, we investigated the efficacy and toxicity of CPE-enhanced nerve blockade across a range of TTX concentrations using 2 CPEs (sodium octyl sulfate and octyl trimethyl ammonium bromide). We also tested the hypothesis that CPEs could be used to reduce the concentrations of TTX and/or of a second adjuvant drug (in this case, epinephrine) needed to achieve prolonged local anesthesia METHODS:: Sprague-Dawley rats were injected at the sciatic nerve with combinations of TTX and CPEs, with and without epinephrine. Sensory and motor nerve blockade were assessed using a modified hot plate test and a weight-bearing test, respectively. Systemic and local toxicities of the different combinations were assessed. RESULTS: Addition of increasing concentrations of TTX to fixed concentrations of CPEs produced a marked concentration-dependent improvement in the rate of successful nerve blocks and in nerve block duration. CPEs did not affect systemic toxicity. At some concentrations, the addition of sodium octyl sulfate increased the duration of block from TTX plus epinephrine, and epinephrine increased that from TTX plus CPEs. The addition of epinephrine did not cause an increase in local toxicity, and it markedly reduced systemic toxicity. CONCLUSIONS: CPEs can prolong the duration of nerve blockade across a range of concentrations of TTX. CPEs could also be used to reduce the concentration of epinephrine needed to achieve a given degree of nerve block. CPEs may be useful in enhancing nerve blockade from site 1 sodium channel blockers.

Near-infrared-actuated devices for remotely controlled drug delivery.

A reservoir that could be remotely triggered to release a drug would enable the patient or physician to achieve on-demand, reproducible, repeated, and tunable dosing. Such a device would allow precise adjustment of dosage to desired effect, with a consequent minimization of toxicity, and could obviate repeated drug administrations or device implantations, enhancing patient compliance. It should exhibit low off-state leakage to minimize basal effects, and tunable on-state release profiles that could be adjusted from pulsatile to sustained in real time. Despite the clear clinical need for a device that meets these criteria, none has been reported to date to our knowledge. To address this deficiency, we developed an implantable reservoir capped by a nanocomposite membrane whose permeability was modulated by irradiation with a near-infrared laser. Irradiated devices could exhibit sustained on-state drug release for at least 3 h, and could reproducibly deliver short pulses over at least 10 cycles, with an on/off ratio of 30. Devices containing aspart, a fast-acting insulin analog, could achieve glycemic control after s.c. implantation in diabetic rats, with reproducible dosing controlled by the intensity and timing of irradiation over a 2-wk period. These devices can be loaded with a wide range of drug types, and therefore represent a platform technology that might be used to address a wide variety of clinical indications.

Local toxicity from local anesthetic polymeric microparticles.

BACKGROUND: Local tissue injury from sustained-release formulations for local anesthetics can be severe. There is considerable variability in reporting of that injury. We investigated the influence of the intrinsic myotoxicity of the encapsulated local anesthetic (lidocaine, low; bupivacaine, high) on tissue reaction in rats. METHODS: Cytotoxicity from a range of lidocaine and bupivacaine concentrations was measured in C2C12 myotubes over 6 days. Rats were given sciatic nerve blocks with 4 microparticulate formulations of lidocaine and bupivacaine: 10% (w/w) lidocaine poly(lactic-co-glycolic) acid (PLGA), 10% (w/w) bupivacaine PLGA, 50% (w/w) lidocaine PLGA, and 50% (w/w) bupivacaine PLGA. Effectiveness of nerve blockade was assessed by a modified hotplate test and weightbearing measurements. Myotoxicity was scored in histologic sections of injection sites. Bupivacaine and lidocaine release kinetics from the particles were measured. RESULTS: Median sensory blockade duration for 50% (w/w) lidocaine was 255 (90-540) minutes versus 840 (277-1215) minutes for 50% (w/w) bupivacaine (P = 0.056). All microparticulate formulations resulted in myotoxicity. The choice of local anesthetic did not influence the severity of myotoxicity. Median myotoxicity scores for 50% (w/w) lidocaine compared with 50% (w/w) bupivacaine at 4 days were 3.4 (2.1-4.2) vs 3.3 (2.9-3.5) (P = 0.44) and at 14 days 1.9 (1.8-2.4) vs 1.7 (1.3-1.9) (P = 0.23), respectively. CONCLUSIONS: Lidocaine and bupivacaine PLGA microspheres resulted in similar degrees of myotoxicity, irrespective of drug loading. Intrinsic myotoxicity did not predict tissue injury from sustained release of these anesthetics. Caution is warranted in the use of such devices near muscle and nerve.

Thiocyanate toxicity: a teaching case.

Introduction: Thiocyanate can cause gastrointestinal, neurologic, and cardiovascular toxicity. Additionally, it interferes with multiple laboratory assays. We present a case of acute thiocyanate toxicity. Case: A 17-year-old female presented with an intentional thiocyanate ingestion. Her course was notable for delirium, wide complex tachycardia, and presumed seizure activity with concurrent lactatemia, acidemia, and narrowing of her arterio-venous oxygen gradient. She received lipid emulsion therapy (LET). While hemodialysis was considered, she recovered without additional treatment. After resolution of her critical illness, a serum cyanide concentration was 0.21 mcg/mL. She had laboratory testing notable for hyperchloremia, hypocalcemia, hypokalemia, and an elevated salicylate concentration attributed to interference by thiocyanate. The thiocyanate was eliminated via first-order kinetics with a half-life of 61.6 hours. Discussion: Thiocyanate poisoning may cause cardiac and neurologic toxicity. Laboratory evidence of impaired cellular respiration in this case suggests possible in vivo conversion to cyanide, however this is not proven. Cyanide antidotal treatment was not administered for this patient, however LET was given based on thiocyanate's lipophilicity. Hemodialysis is known to effectively remove thiocyanate from the blood, however the patient improved without it. The patient's laboratory derangements were due to thiocyanate interference with ion selective electrode and colorimetric analyzer technology. Conclusions: Thiocyanate can cause cardiac and neurologic toxicity, and interferes with several laboratory assays. Theoretically, LET and cyanide antidotal treatment may be useful, but this requires further investigation. Thiocyanate toxicity should be managed supportively, and hemodialysis may be used in severe cases.

Long-acting liposomal corneal anesthetics.

Eye drops producing long-acting ocular anesthesia would be desirable for corneal pain management. Here we present liposome-based formulations to achieve very long ocular anesthetic effect after a single eye drop instillation. The liposomes were functionalized with succinyl-Concanavalin A (sConA-Lip), which can bind corneal glycan moieties, to significantly prolong the dwell time of liposomes on the cornea. sConA-Lip were loaded with tetrodotoxin and dexmedetomidine (sConA-Lip/TD), and provided sustained release for both. A single topical instillation of sConA-Lip/TD on the cornea could achieve 105 min of complete analgesia and 608 min of partial analgesia, which was significantly longer than analgesia with proparacaine, tetrodotoxin/dexmedetomidine solution or unmodified liposomes containing tetrodotoxin and dexmedetomidine. sConA-Lip/TD were not cytotoxic in vitro to human corneal limbal epithelial cells or corneal keratocytes. Topical administration of sConA-Lip/TD provided prolonged corneal anesthesia without delaying corneal wound healing. Such a formulation may be useful for the management of acute surgical and nonsurgical corneal pain, or for treatment of other ocular surface diseases.

Antibody-modified conduits for highly selective cytokine elimination from blood.

Cytokines play an important role in dysregulated immune responses to infection, pancreatitis, ischemia/reperfusion injury, burns, hemorrhage, cardiopulmonary bypass, trauma, and many other diseases. Moreover, the imbalance between inflammatory and antiinflammatory cytokines can have deleterious effects. Here, we demonstrated highly selective blood-filtering devices - antibody-modified conduits (AMCs) - that selectively eliminate multiple specific deleterious cytokines in vitro. AMCs functionalized with antibodies against human vascular endothelial growth factor A or tumor necrosis factor α (TNF-α) selectively eliminated the target cytokines from human blood in vitro and maintained them in reduced states even in the face of ongoing infusion at supraphysiologic rates. We characterized the variables that determine AMC performance, using anti-human TNF-α AMCs to eliminate recombinant human TNF-α. Finally, we demonstrated selective cytokine elimination in vivo by filtering interleukin 1 ß from rats with lipopolysaccharide-induced hypercytokinemia.

Multivesicular liposomal bupivacaine at the sciatic nerve.

Clinical translation of sustained release formulations for local anesthetics has been limited by adverse tissue reaction. Exparel™ (DepoFoam bupivacaine) is a new liposomal local anesthetic formulation whose biocompatibility near nerve tissue is not well characterized. Exparel™ injection caused sciatic nerve blockade in rats lasting 240 min compared to 120 min for 0.5% (w/v) bupivacaine HCl and 210 min for 1.31% (w/v) bupivacaine HCl (same bupivacaine content as Exparel™). On histologic sections four days after injection, median inflammation scores in the Exparel™ group (2.5 of 4) were slightly higher than in groups treated with bupivacaine solutions (score 2). Myotoxicity scores in the Exparel™ group (2.5 of 6) were similar to in the 0.5% (w/v) bupivacaine HCl group (3), but significantly less than in the 1.31% (w/v) bupivacaine HCl group (5). After two weeks, inflammation from Exparel™ (score 2 of 6) was greater than from 0.5% (w/v) bupivacaine HCl (1) and similar to that from 1.31% (w/v) bupivacaine HCl (1). Myotoxicity in all three groups was not statistically significantly different. No neurotoxicity was detected in any group. Tissue reaction to Exparel™ was similar to that of 0.5% (w/v) bupivacaine HCl. Surveillance for local tissue injury will be important during future clinical evaluation.