Midazolam as a sole sedative for computed tomography imaging in pediatric patients

Objective: To evaluate the efficacy and adverse effects of i.v. midazolam as a sole agent for sedation in children for computed tomography (CT) imaging. Materials and Methods: Prospective clinical trial in which 516 children under ASA classification II–IV (273 boys and 243 girls) in the age group of 6 months to 6 years for elective CT scan were enrolled over a 17‐month period. Patients were administered i.v. midazolam 0.2 mg·kg^?1 and further boluses of 0.1 mg·kg^?1 (total 0.5 mg·kg^?1) if required. Measurements included induction time, efficacy, side effects, complications, and degree of sedation. Sedation was graded on the basis of Ramsay sedation score (RSS) as over sedated (RSS 5–6), adequately sedated (AS, RSS 3–4), under sedated (RSS 1–2), or failed if the procedure could not be completed or another agent had to be administered. Results: Of the 516 procedures, 483 brains, 16 chests, and 17 abdomens were scanned with a mean duration of 4.75 ± 1.75 min with a mean dose of 0.212 mg·kg^?1 of i.v. midazolam. Four hundred and sixty‐five (90.12%) patients were AS in 5.9 ± 0.7 min while 40 (7.75%) patients required additional boluses. Of these 40 patients, 24 (4.65%) required a single bolus, 12 (2.32%) required two boluses, whereas the remaining four (0.78%) required three boluses. In 11 (2.13%; P < 0.0001) patients, the scan could not be completed satisfactorily. Side effects were seen in 46 (9.11%) patients in the form of desaturation, hiccups (seven patients, 1.38%), and agitation (four patients, 0.79%). Desaturation (SpO₂ 90–95%) was seen in 35 (6.93%) patients, which was corrected by topical application of oxygen. None of the patients exhibited any complications such as pulmonary aspiration or need to maintain airway. The patients were kept under observation for 1 h after the procedure. Conclusion: The level of sedation achieved in children with midazolam 0.2 mg·kg^?1 is adequate for imaging with minimal side effects, no airway complications, and fast recovery. It can be recommended as the sole agent for sedation in pediatric patients for CT imaging.     

Ethical concerns in the management of pain in the neonate

The debate about the management of pain in the neonate has continued to evolve over the past 30 years. This controversy can be understood as evolving through now three eras of thought about the effect of pain and its management in newborns and infants. The first generation was characterized by a widespread belief that newborns lacked the complete development of the neuroanatomical and neuroendocrine components necessary to perceive pain. During this period, newborns often received inadequate anesthesia and analgesia for painful procedures, if not no treatment at all. The second generation was heralded by research that demonstrated that newborns did demonstrate similar or even exaggerated physiological and hormonal responses to pain compared with those observed in older children and adults and that exposure to prolonged or severe pain may increase neonatal morbidity. Controversy in this generation focused around the dosage of analgesia to newborns as well as the risks and benefits of pain management techniques. We are now in a third generation of thought about pain in the neonate, defined by intense debate over the significance of a growing number of studies in immature animal models that demonstrate degenerative effects of several anesthetics on neuronal structure. The challenge of this era is to integrate the advances in diagnosis and treatment achieved in previous generations with ongoing adaptation of clinical practice as dictated by research advances in the field. In this review, we examine the evolution of medical thought and ethical concerns regarding pain treatment in the neonate.     

局部麻醉药脊髓神经毒性及其防治研究进展

近年来,有关局麻药脊髓神经毒性的报道日渐增多并业已引起广泛的关注。本文就局麻药脊髓神经毒性的临床表现,可能发生机制、相关影响因素以及综合防治措施作一简要综述。     

Molecular properties of local anesthetics as predictors of affinity for nicotinic acetylcholine receptors

In spinal anesthesia, the effects of local anesthetics (LAs) are not completely explained by sodium channel inhibition. Other targets include neuronal nicotinic acetylcholine receptors (nAChRs). LA affinities for the Torpedo californica nAChR were measured by inhibition of [(3)H]TCP binding and correlated with molecular volume, surface area, molecular weight, and log of the octanol-water partition coefficients (P and D). To understand the molecular determinants important for interaction with the nAChR, ester and amide LAs were compared separately. Also, correlations with the aromatic/linker half and the hydrophilic half of the LA molecules were considered individually. The IC(50)s of the ester LAs correlated better with the molecular volume, surface area, molecular weight, and log P of the aromatic/linker half of the molecules; whereas the IC(50)s for amide LAs correlated better with the four parameters based on the hydrophilic half. These correlations were used to predict the IC(50) of various LAs (including several not studied here) and to compare these values with the published values. The predicted values of IC(50) correlated well with the published results both for neuronal and for electroplaque-desensitized nAChR, suggesting that the results can be generalized to include neuronal nAChRs.     

麻醉药及其辅助药物基因组学的研究进展

临床上麻醉药及其辅助药物治疗的个体化差异备受关注。目前,越来越多的研究着重于麻醉药物与转运蛋白、作用靶受体和代谢酶的基因多态性之间的关系．并发现麻醉药物效应与相关基因多态性存在密切联系。本文就近年来麻醉药及其辅助药物基因组学的研究进展作一综述。     

Continuous peripheral nerve block for postoperative pain control at home: a prospective feasibility study in children

BACKGROUND AND OBJECTIVES: We assessed the feasibility and efficacy of postoperative pain control by continuous peripheral nerve blockade (CPNB) in children after early home discharge under parental surveillance. METHODS: All children scheduled for primary elective ankle or foot surgery under sciatic popliteal CPNB and general anesthesia were evaluated. After obtaining the surgeon's consent, the children were discharged on either the day (D) of surgery (D0), or on postoperative D1 or D2 (depending on whether they needed a plaster cast or a suction drainage). The CPNB was continuously infused, using an elastomeric pump. Before the procedure, the parents were taught how to assess their children's pain, to use rescue analgesia, and to manage an infusion elastomeric pump device, and when to call the hospital in case of emergency. The children returned to the hospital for catheter removal and the recording of any postoperative event. RESULTS: Forty-seven children were entered into this observational study. Two were discharged home on the same day, 30 were discharged home 1 day after surgery, and 15 were discharged home 2 days after surgery. The mean duration of infusion elastomeric pump at home was 3 days (range, 2 to 4 days). Analgesia was rated as excellent or good in 89% of the cases, and the quality of sleep was always good, except for three patients. Some minor untoward effects were recorded. Two children returned to the hospital because of accidental disconnection of the infusion elastomeric pump from the catheter. Four patients presented skin redness at the puncture site, but no infection was observed, and all catheters remained sterile. No parents called the hospital. The children's quality of life was rated as excellent or as satisfactory overall, by both the children and their parents. CONCLUSIONS: Shortening hospital stays with the use of at-home CPNB under sole parental supervision is feasible, after selecting children with a suitable family environment.     

Rapid sequence intubation without a neuromuscular blocking agent in a 14-year-old female patient with myasthenia gravis

The anesthesia care of a 14-year-old female patient with an acute exacerbation of myasthenia gravis (MG) and a full stomach who required emergency surgery for placement of a hemodialysis catheter is described. A nonventilated rapid sequence induction was successful with the use of propofol, lidocaine, remifentanil, cricoid pressure and no neuromuscular blocking agent. Although the use of combinations of i.v. anesthetic agents have been suggested for tracheal intubation without the need for neuromuscular blocking agents, none of these techniques has been advocated for rapid sequence intubation. We review existing literature on the topic of tracheal intubation using remifentanil and propofol without a neuromuscular blocking agent and on the topic of tracheal intubation of patients with MG using i.v. anesthesia and no neuromuscular blocking agents.     

静脉麻醉药对原代培养大鼠心肌细胞的毒性作用

目的 :探讨静脉麻醉药对原代培养大鼠心肌细胞的直接作用。方法 :将经原代培养成活 4天后的大鼠心肌细胞分为 9组 ,每组 6孔 ,对照组为C组 ,其余 8组分别为小剂量与大剂量硫喷妥钠组 (TL ,1× 10 -5mol/L与TH ,1×10 -4 mol/L) ;小剂量与大剂量氯胺酮组 (KL ,1× 10 -5mol/L与KH ,1× 10 -4 mol/L) ;小剂量与大剂量γ 羟基丁酸钠组(HL ,3× 10 -3mol/L与HH ,3× 10 -2 mol/L) ;小剂量与大剂量异丙酚组 (PL ,3× 10 -5mol/L与PH ,3× 10 -4 mol/L)。各组均于实验开始后 8小时评定心肌细胞搏动功能、观察细胞形态学改变、测定心肌细胞酶及电解质变化。结果 :与对照组相比 ,KL组心肌细胞搏动频率加快 (P <0 0 5 ) ,TL、KH及PH组搏动频率明显减慢 (P <0 0 5和P <0 0 1) ,TH组可见心肌细胞呈部分搏动或无搏动。细胞形态学亦有相应变化。LDH、AST与CK释放量增加 (P <0 0 5和P <0 0 1) ,ALP活性下降。而HL、HH、KL及PL组对上述指标无明显影响。各组间电解质变化未见显著差异。结论 :低浓度的硫喷妥钠以及高浓度的氯胺酮、异丙酚均有直接的心肌抑制作用 ,高浓度的硫喷妥钠尤为明显。而γ 羟基丁酸钠及低浓度的氯胺酮、异丙酚几无心肌细胞毒性作用 ,事实上 ,低浓度的氯胺酮表现出正性变时性和变力性作用     

Metabolites of methohexitone do not contribute to its prolonged action on the central nervous system

Methohexitone has been reported to have a prolonged action on the central nervous system (CNS) despite its relatively short elimination half-life. A hydroxy metabolite of methohexitone was identified, purified and isolated from the urine collected from eight surgical patients and five mongrel dogs anaesthetized with methohexitone. Using a rotarod device, the CNS-activity of the human and canine metabolites was tested in mice and compared to that of methohexitone. In this test, the metabolites showed CNS-depressant activity, but the ED50 (dose needed to affect 50% of the animals) of the metabolites was ten times higher than the ED50 of the parent drug. Because in patients, no traces of the hydroxy metabolite could be found in blood, and in dogs the plasma concentration of the metabolite was about two-thirds of that of the parent compound, it is unlikely that the residual CNS-effects of methohexitone are due to its major metabolite, hydroxymethohexitone.