2种升压药对剖宫产新生儿血气影响的Meta分析

目的:利用Meta分析方法评价苯肾上腺素和麻黄素对剖宫产新生儿血气的影响。方法:查阅中国期刊全文数据库(CNKI)、PubMed、万方数据库、维普中文科技期刊全文数据库(VIP)、中国生物医学文献数据库(CBM)2000-2011年3月公开发表的随机对照临床试验文献,按照纳入与排除标准选择文献、评价质量和提取数据,采用RevMan4.2软件进行Meta分析。结果:纳入10篇文献,2组新生儿脐动脉血的pH值[WMD=0.05,95%CI(0.04,0.06),P<0.00001]和氧分压(PO2)[WMD=0.52,95%CI(0.08,0.96),P=0.02]以及二氧化碳分压(PCO2)[WMD=-4.35,95%CI(-5.00,-3.69),P<0.00001]差异均有统计学意义;2组新生儿脐动脉血的剩余碱(BE)[WMD=1.38,95%C(I-0.15,2.92),P=0.08]差异无统计学意义。结论:苯肾上腺素有利于增加胎儿氧供,降低缺氧性酸中毒,值得临床推广应用。     

Effect of low dose phenylephrine infusion on shivering and hypothermia in patients undergoing cesarean section under spinal anesthesia: a randomized clinical trial

BackgroundShivering is a common complication of spinal anesthesia. Phenylephrine, due to its peripheral vasoconstrictive effect, may limit the core to periphery redistribution of body temperature following spinal anesthesia, and reduce hypothermia and shivering. We hypothesized that prophylactic phenylephrine infusion would reduce shivering and hypothermia in women undergoing cesarean section under spinal anesthesia.MethodsA two-arm randomized, double-blind, placebo-controlled trial in term pregnant patients undergoing cesarean section. In the phenylephrine group (n=75) prophylactic phenylephrine infusion was administered at 25 µg/min immediately after initiation of spinal anesthesia and continued until the end of the operative period. In the placebo group (n=75) a normal saline infusion was administered during the same period. The primary outcome was the incidence of shivering; secondary outcomes were severity of shivering, changes in nasopharyngeal (core) temperature, and incidence of hypotension and bradycardia.ResultsThe incidence of shivering in the phenylephrine and control groups was 24.0% (95% CI 14.3% to 33.7%) and 53.3% (95% CI 42.0% to 64.6%), respectively. The severity of shivering was greater in the control group (P=0.002) and the mean (±SD) end of surgery core temperature was significantly higher in the phenylephrine group (35.84°C ± 0.60) compared with controls (35.61°C ± 0.48) (P=0.009). The incidence of hypotension was higher in controls (53.4% vs. 2.7%; P <0.001) but bradycardia more frequent in group P (P=0.023).ConclusionThe incidence of shivering and degree of hypothermia were significantly reduced by a prophylactic phenylephrine infusion during cesarean section under spinal anesthesia.     

Benzalkonium chloride,a common ophthalmic preservative,compromises rat corneal cold sensitive nerve activity

PurposeCorneal nerves comprise the densest sensory network in the body. Dysfunction of the corneal cold sensitive neurons (CSN) is implicated in ophthalmic disorders, including Dry Eye Disease, the most common ocular surface disorder. The preservative Benzalkonium chloride (BAK) and the mydriatic agent Phenylephrine hydrochloride (PHE) are considered to be inactive at the level of the CSNs. The purpose of this study is to test the impacts of continuous exposures to BAK or PHE at their clinically used concentrations on corneal nerve structure and function.MethodsIn vivo extracellular electrophysiology of the rat trigeminal ganglion was used to monitor CSN functional response to stimuli mimicking physiological states and stressors of the cornea. Corneal nerve structure was evaluated by immunostaining.ResultsAmong the tested stimuli, cold probe receptive field stimulation and hyperosmolar stress were the most sensitive methods of detecting activity changes. CSN activity was attenuated after 30 min exposure to either PHE or BAK. After an hour-long washout period, BAK-treated neurons failed to recover activity while PHE-treated neurons showed signs of functional recovery. Intraepithelial nerve density was reduced and nerve fragmentation was increased in BAK-treated corneas, while PHE exposure left corneal nerves structurally intact.ConclusionsOur study suggests that prolonged ocular instillations of BAK or PHE alter CSN activity through two different processes — irreversible neuronal damage in the case of BAK vs. reversible attenuation in the case of PHE.     

Comparison of the potency of phenylephrine and norepinephrine bolus doses used to treat post-spinal hypotension during elective caesarean section

BackgroundPhenylephrine, although considered the vasopressor of choice, can cause reflex bradycardia and a fall in cardiac output. Norepinephrine, due to its direct positive chronotropic and reflex negative chronotropic actions, is expected to overcome this problem. However, limited information about its effective dose for management of post-spinal hypotension, and its potency compared to phenylephrine, is available.MethodsOne hundred consecutive patients who developed post-spinal hypotension were treated with a predetermined dose of either phenylephrine or norepinephrine. Correction of hypotension after one minute was considered ‘success’. The starting dose for the first patient and testing interval (the incremental or decremental dosing) were 100 μg and 10 μg in the phenylephrine group, and 6 μg and 0.5 μg in the norepinephrine group. Doses for subsequent patients were determined by the responses of previous patients according to the Narayana rule for up-down sequential allocation. ED95 and ED50 of phenylephrine and norepinephrine boluses and their potency ratio were calculated.ResultsUsing Probit analysis, ED95 and ED50 values were 43.1 µg (95% CI 39.5 to 65.0 µg) and 33.2 µg (95% CI 5.1 to 37.0 µg) for phenylephrine, and 3.7 µg (95% CI 3.5 to 4.7 µg) and 3.2 µg (95% CI 1.8 to 3.4 µg) for norepinephrine. The relative potency ratio of norepinephrine and phenylephrine was 11.3 (95% CI 8.1 to 16.9).ConclusionBased on the results of this study, norepinephrine is about 11 times more potent than phenylephrine. When used as bolus doses for treatment of hypotension, 100 μg phenylephrine should be approximately equivalent to 9 μg norepinephrine.     

苯肾上腺素对乳兔心室肌细胞电生理特征的影响

目的 探讨苯肾上腺素诱导兔心室肌细胞肥大过程中心肌细胞电生理特性的改变及意义.方法将24只新西兰乳兔随机分为苯肾上腺素组和正常对照组各12只.体外原代培养乳兔心室肌细胞,苯肾上腺素组给予10 μmol/L苯肾上腺素持续作用48 h后,应用全细胞膜片钳技术观察心室肌细胞膜电容、动作电位时程和快激活延迟整流钾电流的变化,并与对照组比较.结果 苯肾上腺素作用48 h后,心室肌细胞膜电容较正常对照组增加36.4%（P＜0.01）;心室肌细胞动作电位复极达90%时限较对照组延长18.8%（P＜0.01）;心室肌细胞快激活延迟整流钾电流尾电流密度较对照组下调24.1%（P＜0.05）.结论 苯肾上腺素长期持续刺激可诱导心室肌细胞肥大并发生电重构,可能是导致室性心律失常发生的一个重要机制.     

苯肾上腺素预注射用于剖宫产术脊麻后低血压的剂量效应

目的 探讨苯肾上腺素对剖宫产术脊麻后低血压的合适预注射剂量。 方法 择期行剖宫产术产妇80例,ASAⅠ或Ⅱ级,随机分成4组(n=20):苯肾上腺素预注射50 μg(P1组)、100 μg(P2组)、150 μg(P3组)和对照组(C组,无预注射),快速输注羟乙基淀粉130/0.4氯化钠至胎儿取出前(控制总量≤500 mL,于L_3~4间隙鞘内注入布比卡因9 mg+吗啡0.2 mg,注药后随即产妇平卧位静脉注射上述不同剂量的苯肾上腺素,胎儿取出前若发生产妇低血压,给予适当(50 μg或100 μg)苯肾上腺素静脉注射。 结果 胎儿取出前低血压发生率组间差异无统计学意义(P>0.05),心动过缓发生率组间差异有统计学意义(P<0.05);所有产妇未发生反应性高血压;随着苯肾上腺素预注射剂量增加,各组产妇胎儿取出前平均最低收缩压(SBP)增加,但差异无统计学意义(P>0.05),并且随着鞘内苯肾上腺素预注射剂量的增加低血压出现时间延迟且低血压出现的次数及苯肾上腺素总干预剂量逐渐减小,组间差异均有统计学意义(P<0.05)。术中恶心呕吐发生率,新生儿Apgar评分和脐静脉血气组间差异无统计学意义(P>0.05)。 结论 苯肾上腺素预注射100 μg联合胶体快速输注有利于减少择期剖宫产脊麻后低血压发生次数,心动过缓发生率较低,能较好维持产妇血流动力学稳定。     

Cost of care for patients with age-related macular degeneration in Switzerland and cost-effectiveness of treatment with verteporfin therapy

The cost-effectiveness of photodynamic therapy with verteporfin in the treatment of patients with predominantly classic subfoveal choroidal neovascularization secondary to age-related macular degeneration was investigated by a Markov Model over a time horizon of three years in Switzerland. This model describes patients moving between three levels of visual acuity (e.g., good vision, impaired vision, highly impaired vision) and death in terms of transition probabilities. Transition probabilities as well as effectiveness values were derived from a randomized, controlled, double-masked clinical trial. Effectiveness for verteporfin therapy and for placebo was calculated in terms of vision years: 1.068 and 0.494, respectively. Cost per level of visual acuity was assessed in ascending order by expert panels from a societal perspective. Cost strongly increased parallel with vision loss on a patient-per-year basis from 4683 CHF at good vision to 8443 CHF at impaired vision, and was highest with 15231 CHF at highly impaired vision. The model-calculated cost per visionyear were 14907 CHF for patients in the verteporfin therapy group, versus 21047 CHF for patients in the placebo group. The incremental cost per vision-year additionally saved through verteporfin therapy was 9624 CHF. The study demonstrated that greater effectiveness of verteporfin therapy versus placebo compensated for the cost of the therapy so that verteporfin therapy was clearly costeffective. Therefore, for the indicated patients with AMD that causes severe vision loss, verteporfin therapy can be recommended as the therapy of choice, on both clinical and economic grounds.     

不同剂量去氧肾上腺素静脉注射对腰麻下剖宫产产妇及新生儿的影响

目的观察不同剂量去氧肾上腺素静脉注射对腰麻下剖宫产产妇及新生儿的影响。方法择期腰麻剖宫产单胎产妇60例,随机均分为三组,在蛛网膜下腔注入0.5%重比重布比卡因2.5ml,鞘内注药后立即静脉泵注去氧肾上腺素150μg(P1组)、300μg(P2组)或等量生理盐水(C组)各3ml,速率1ml/min。若发生低血压时追加去氧肾上腺素100μg。监测并记录产妇SBP、DBP、HR、每搏输出量(SV)和心输出量(CO),以及低血压、高血压、恶心呕吐及心动过缓的发生次数。记录新生儿Apgar评分,并取脐带动静脉血行血气分析。结果与入室后比较,腰麻后1、5minC组SBP、DBP明显降低(P<0.05),P1、P2组无显著变化;腰麻后1、5min和分娩前1minP1、P2组HR明显减慢,C组仅在分娩前1min显著减慢(P<0.05);腰麻后1、5minP2组SV显著升高,腰麻后5minC组显著降低(P<0.05),且腰麻后5minP1、P2组明显高于C组(P<0.05);腰麻后5min和分娩前1minP1、P2组CO显著降低(P<0.05),分娩前1minC组也显著降低(P<0.05)。P1组和P2组低血压的发生率显著低于C组(P<0.05)。P1组和P2组分别有1例和3例高血压。结论小剂量去氧肾上腺素静脉输注能减少分娩前产妇低血压的发生率,对母体和胎儿影响较小。