Evolving Techniques in RSI: Can the Choice of Induction Agent Matter in Securing a Definitive Airway in Emergency Settings?

How to cite this article: George B, Joachim N. Evolving Techniques in RSI: Can the Choice of Induction Agent Matter in Securing a Definitive Airway in Emergency Settings? Indian J Crit Care Med 2022;26(1):15–17.     

Inhaled mannitol in cystic fibrosis

Inhaled mannitol has recently been given fast-track status as an investigational drug to treat the lung manifestations of cystic fibrosis. It seems to work in a similar way to nebulized hypertonic saline, osmotically inducing water flux into the bronchial lumen, thereby increasing the hydration of airway mucus, which can then be cleared more effectively by mucociliary clearance and coughing. Short-term studies have shown good tolerability and improvements in lung mucociliary clearance. Longer-term studies studying end points of clinical relevance are ongoing. This article assesses its likely future role in cystic fibrosis.     

The neurotoxicity of intrathecal lidocaine is enhanced in postpartum compared to virgin rats

During the perinatal period, the pharmacokinetics and pharmacodynamics of drugs may be altered. Data about the neurotoxicity of intrathecal local anesthetics in the peripartum period are lacking. So we hypothesized that the neurotoxicity of intrathecal lidocaine during perinatal period may be changed. Therefore, we designed the present study to determine whether the neurotoxicity of intrathecal lidocaine in postpartum rats would be different from that in nonpregnant, virgin rats. Postpartum and nonpregnant rats randomly received an intrathecal infusion of lidocaine 50 mg/mL in saline, lidocaine 20 mg/mL in saline, or saline for 1 h at a rate of 1 μL/min. Four days after drug infusion, the rats were assessed for persistent impairment of sensory and motor function (MF) using the tail‐flick (TF) test, paw pressure test, and MF score. Spinal cords and nerve roots were obtained for light and electron microscopic examinations, and the injury scores were compared between groups. The TF latencies and the mean nerve injury scores of the postpartum group were significantly higher than those of nonpregnant group. Lidocaine induced a dose‐dependent impairment in TF latencies and nerve injury scores. There was no significant interaction between postpartum and the drug. Our results suggest that the neurotoxicity of intrathecal lidocaine is enhanced in rats during the early postpartum period compared with nonpregnant, virgin rats.     

Anesthetics attenuate ischemia–reperfusion induced renal injury: Effects and mechanisms

Acute kidney injury (AKI) secondary to ischemia–reperfusion injury (IRI) is a major cause of patient morbidity and mortality in the perioperative period. It can lead to new onset of chronic kidney disease and accelerate its progression. Patients with risk factors undergoing cardiac, vascular, and liver transplantation surgeries, which may inevitably involve IRI, are more susceptible to AKI. Anesthetic agents have been postulated to possess renoprotective properties. Thus, exploring the utilization of selective perioperative anesthetic agents with renoprotective properties may be a promising avenue to reduce the risk of AKI. This review discusses the effects and mechanisms of dexmedetomidine, inhalational and intravenous anesthetics, and xenon-mediated renoprotection. Although the renoprotective effects of these agents obtained in the laboratory are promising, much work especially via clinical trials is required to determine the translational value from the bench to the bedside.     

脂肪乳剂——局部麻醉药心脏毒性反应救治的新发现

局部麻醉药心脏毒性反应是临床上局部麻醉和椎管内麻醉实施过程中罕见、但可能是致命的并发症。由于缺乏特异性的拮抗药物,对症治疗是目前临床医师最主要的处理手段。本文综述现有相关基础研究及临床应用案例,介绍一种有可能给救治局部麻醉药心脏毒性反应带来革命性改变的药物——脂肪乳剂,供临床医师参考。     

麻醉药物对硬膜外阻滞利多卡因药动学的影响

目的：麻醉药物对硬膜外阻滞利多卡因药动学影响进行研究。方法：分别对12例腹部及下肢手术患者硬膜外阻滞加全麻和腰麻-硬膜外联合阻滞麻醉后的药动学参数进行研究和评价，采用荧光偏振免疫方法（FPIA）测定血中利多卡因浓度，3P97程序进行药动学参数线性拟合，t检验比较组间差异。结果：硬膜外阻滞加全麻和腰麻-硬膜外联合阻滞注药后，血药浓度达峰时间分别为（8．4±0．6）min和（9．0±0．6）min（P〉0．05），血药峰值分别为（2．16±0．25）mg·L^-1和（2．02±0．20）mg·L^-1（P〉0．05），吸收速率常数分别为（19．3±4．4）h^-1和（19．4±4．8）h^-1（P〉0.05），消徐半衰期分别为（3．3±1．7）h和（2．6±0．6）h（P〉0．05）。结论：麻醉药物对硬膜外阻滞利多卡因药动学无显著影响，可以安全使用。     

Effects of high thoracic epidural anesthesia and local anesthetics on bronchial hyperreactivity

Bronchial hyperreactivity can cause life threatening bronchospasm after airway irritation. Therefore, endotracheal intubation is avoided in asthmatics when feasible. High thoracic epidural anesthesia can be used to avoid endotracheal intubation and offers less postoperative pulmonary complications when compared to systemic postoperative analgesia. However, there are concerns that it might also cause impaired ventilation by extended motor blockade, increased airway resistance, and increased bronchial reactivity because of pulmonary sympathicolysis. Nevertheless, high thoracic epidural anesthesia causes only a slight decrease in vital capacity and neither an increase in airway resistance nor increased bronchial reactivity. In fact, it causes a decrease in bronchial reactivity in patients with bronchial hyperreactivity mostly due to the systemic effect of the local anesthetic. The attenuation of bronchial hyperreactivity can be shown as a dose dependent effect of lidocaine and bupivacaine. The intravenous effect of lidocaine is comparable to the effect of a moderate dose of salbutamol and leads to an additive effect when both drugs are used in combination. Overall, high thoracic epidural anesthesia can be used safely in patients with bronchial hyperreactivity and intravenous administration of lidocaine (1.5–2.0 mg · kg⁻¹) can be used as a prophylactic treatment prior to airway instrumentation. This revised version was published online in July 2006 with corrections to the Cover Date.     

不同静脉麻醉药对诱导和气管插管期间血压、ET和NO的影响

目的 探讨硫喷妥钠、异丙酚、依托咪酯诱导对气管插管期间血压、脉搏及其内皮素(endothelin,ET)、一氧化氮(nitric oxide,NO)的影响.方法 择期气管插管全麻患者40例,随机分为3组:硫喷妥钠组(T组)、异丙酚组(P组)、依托咪酯组(E组).常规全麻诱导气管插管,分别在诱导前、诱导后插管前、插管后1、3、5 min记录血压、心率,并同时收集血样,分别采用放射免疫技术和硝酸还原酶法测定血中ET、NO的浓度.结果 全麻诱导后P组血压下降幅度最大,P组ET显著降低,T组和P组的NO显著升高.气管插管后1 min各组血压、脉搏均显著升高,各组ET、ET/NO均升高,NO均降低.结论 3种药物临床剂量对血压的抑制程度分别为异丙酚＞硫喷妥钠＞依托咪酯,并与对应时间点体内ET、NO的变化有相关关系.     

Structural effects of the topical lidocaine-prilocaine anesthetic Emla on the tympanic membrane

Summary A eutectic mixture of two anesthetic solutions is that of lidocaine and prilocaine, which is available commercially as Emla (eutectic mixture of local anesthetics). This solution is commonly used in clinics in superficial skin surgery and when inserting intravenous catheters, and we also wanted to determine its surface effects when applied onto the tympanic membranes (TM) of rats and guinea pigs as animal models. The animals were observed by otomicroscopy for 2 weeks up to 5 months after administrations of the anesthetic solution. Tissue specimens were then obtained for light microscopy and fine structural analysis. The application of Emla caused minor structural changes to the rat TM, but hardly any alterations to that of the guinea pig. The changes displayed were an overall increased thickness, with typical submucosal edema but only slight epithelial reaction. In comparison with previous results with lidocaine, phenol and Bonain's solution, Emla seemed to be harmless to the structure of the TM. However, the efficacy of Emla as a topical TM anesthetic remains to be proved in future clinical trials.     

Effects of propofol on cerebral blood flow and the metabolic rate of oxygen in humans

BACKGROUND: Effects of propofol on human cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and blood flow-metabolism coupling have not been fully evaluated. We therefore assessed the effects of propofol on total-CBF and CMRO2 in patients without noxious stimuli and neurologic disorders. METHODS: General anesthesia was induced with midazolam (0.2 mg/kg) and fentanyl (5 microg/kg) in 10 patients (ASA physical status I) undergoing knee joint endoscopic surgery. Epidural anesthesia was also performed to avoid noxious stimuli during surgery. Cerebral blood flow (CBF) and cerebral arteriovenous oxygen content difference (a-vDO2) was measured using the Kety-Schmidt method with 15% N2O as a tracer before and after propofol infusion (6 mg/kg/h for 40 min), and the CMRO2 was also calculated. RESULTS: CBF decreased following propofol infusion from 34.4 ml/100 g/min (range 28.4-52.0) to 30.0 ml/100 g/min (range 20.2-42.4) (P=0.04). Although there was no significant change in a-vDO2, CMRO2 decreased following propofol infusion from 2.7 ml/100 g/min (range 2.2-4.3) to 2.2 ml/100 g/min (range 1.4-3.0) (P=0.04). There was a strong linear correlation between CBF and CMRO2 (r=0.90). CONCLUSION: Propofol proportionally decreased CBF and CMRO2 without affecting a-vDO2 in humans, suggesting that normal cerebral circulation and metabolism are maintained.