长时间CO2气腹和Trendelenburg体位对中老年患者直肠癌根治术中脑氧饱和度的影响

目的评估腹腔镜下直肠癌根治术中长时间CO2气腹和Trendelenburg体位对中老年患者脑氧饱和度(rSO2)的影响。方法选择拟行腹腔镜下直肠癌根治术患者38例,男19例,女19例,年龄45~80岁,BMI 18~25kg/m2,ASAⅠ或Ⅱ级。根据年龄分为两组:45~64岁为中年组(M组),65~80岁为老年组(O组)。两组均常规全麻插管,记录诱导结束后10 min(T0)、Trendelenburg体位后30 min(T1)、1 h(T2)和2 h(T3)的HR、MAP、PETCO2、PaCO2、PaO2、rSO2等。采用Pearson检验分析rSO2与年龄的相关性。记录术后3 d内急性脑卒中和术后谵妄(POD)等神经系统相关不良反应的发生情况。结果与T0时比较,T1-T3时两组rSO2均明显升高(P<0.05)。T0时M组rSO2明显高于O组(P<0.05)。不同时点两组HR、MAP、PETCO2、PaCO2、PaO2差异无统计学意义。T0时rSO2与年龄呈明显负相关(r=-0.650,P<0.05)。T1、T2时rSO2与年龄未见明显相关性。T3时rSO2和年龄之间呈明显正相关(r=0.488,P<0.05)。两组术后无一例急性脑卒中和POD等神经系统相关不良反应发生。结论在需要Trendelenburg体位的腹腔镜手术中,尤其对于老年患者,应该加强rSO2监测,避免脑氧供氧需失衡带来的神经系统并发症。     

FloTrac/Vigileo监测不同CO2气腹压对腹腔镜妇科手术患者血流动力学的影响

目的探讨应用FloTrac/Vigileo系统监测CO2气腹下不同腹内压(IAP)对腹腔镜妇科手术患者血流动力学的影响。方法 60例择期行腹腔镜妇科手术患者,按随机数字表法均分为三组:IAP分别为8mmHg(A组)、12mmHg(B组)、15mmHg(C组)。FloTrac/Vigileo系统监测患者血流动力学变化。记录麻醉后5min(T0)、气腹后1min(T1)、气腹后5min改变体位时(T2)、气腹后15min(T3)、气腹结束恢复体位后1min(T4)、5min(T5)时HR、MAP、CVP、外周血管阻力(SVR)和心输出量(CO),记录不良反应的发生情况。结果与T0时比较,T1～T3时三组HR明显增快,MAP和SVR明显升高(P<0.05);T1～T3时A组、T2、T3时B组CVP明显升高(P<0.05);T1～T3时B、C组CO明显降低(P<0.05)。T1～T3时C组的HR明显快于,MAP和SVR明显高于A、B组(P<0.05);T1～T3时B、C组CO明显低于A组,且C组明显低于B组(P<0.05)。C组术中心律失常和术后恶心呕吐的发生率明显高于A、B组(P<0.05)。结论 FloTrac/Vigileo系统监测下的CO2气腹腹内压12mmHg对血流动力学影响较小,适合腹腔镜妇科手术患者。     

不同气腹压力对腹腔镜妇科手术患者颅内压的影响

目的应用超声测量视神经鞘直径(ONSD)评价不同气腹压力下腹腔镜妇科手术患者颅内压(ICP)的变化。方法择期行腹腔镜妇科手术患者40例,年龄18～65岁,BMI 18～25 kg/m~2,ASAⅠ或Ⅱ级,采用随机数字表法分为两组(n=20):低气腹压力组(A组)和高气腹压力组(B组)。常规麻醉诱导和机械通气。手术开始时行CO_2气腹,A组气腹压力为10 mmHg,B组为14 mmHg。气腹后调整体位为30°头低脚高位,手术结束时恢复为仰卧位。超声测量患者右眼ONSD,根据ONSD计算ICP_(ONSD)。记录麻醉诱导后气腹前(T_0)、气腹后1min(T_1)、头低脚高位即刻(T_2)、气腹后30 min后(T_3)、气腹后60 min后(T_4)、手术结束后5 min(T_5)、15 min(T_6)时的P_(ET)CO_2、PaCO_2、MAP、HR、ONSD和ICP_(ONSD)。结果与T_0时比较,T_4、T_5时两组P_(ET)CO_2、PaCO_2明显升高,T_4—T_6时MAP明显升高(P0.05);T_4—T_6时A组,T_3—T_6时B组HR明显增快(P0.05)。与A组比较,T_3、T_4时B组MAP明显升高,HR明显增快(P0.05)。与T_0时比较,T_4、T_5时A组ONSD、ICP_(ONSD)明显升高,T_3—T_5时B组ONSD、ICP_(ONSD)明显升高(P0.05)。与A组比较,T_3时B组ONSD、ICP_(ONSD)明显升高(P0.05)。结论 10 mmHg和14 mmHg气腹压力均可引起腹腔镜妇科手术患者ONSD和ICP升高,其中14 mmHg气腹压力对ONSD和ICP的影响更大。     

腹腔镜手术中头低脚高体位气腹建立后对冠状动脉血流量的影响分析

目的探讨头低脚高的体位处理对腹腔镜手术期间气腹建立后冠状动脉血流量的影响。方法选取2015年4月至2016年3月行腹腔镜手术的患者56例作为研究对象,根据体位的不同分为头低脚高组(A组,28例)和头高脚低组(B组,28例)。比较两组患者在气腹前(T0)、气腹后10 min(T1)、体位改变后5 min(T2)、10 min(T3)及20 min(T4)各时间点的心率(HR)、平均动脉压(MAP)、呼气末二氧化碳分压(P_(et)CO_2)及冠状动脉左前降支(LAD)的直径及血流量。应用SPSS 17.0软件对所有临床数据进行统计学分析,体位改变后各时间点HR、MAP、P_(et)CO_2、LAD变化、血流动力学指标、手术时间以均数±标准差(±s)的形式表示,组间比较采用t检验;计数资料以n(%)的形式表示,采用χ~2检验;以P0.05表示差异有统计学意义。结果与气腹前(T0)时间点相比,两组患者的T1、T2、T3、T4时间点的HR、MAP、P_(et)CO_2、LAD直径和血流量均显著下降(P0.05);与气腹后10 min(T1)时间点相比,A组患者的T2、T3、T4时间点的P_(et)CO_2及LAD直径和血流量显著下降,差异有统计学意义(P0.05)。结论腹腔镜手术时头低脚高体位可对患者的冠状动脉的血流量产生影响,临床应加强监护。     

不同呼气末二氧化碳分压对室间隔缺损修补术患儿脑氧合及脑血流的影响

目的探讨不同P_(ET)CO_2对室间隔缺损修补术患儿脑氧合及脑血流的影响。方法择期行室间隔缺损修补术患儿60例,随机分为两组,每组30例。低通气组(L组):调控V_T和RR,以维持P_(ET)CO_2在40～45 mmHg;高通气组(H组):调控V_T和RR,以维持P_(ET)CO_2在35～40 mmHg。记录麻醉诱导后(T_0)、开心包(T_1)、CPB结束(T_2)、改良超滤结束(T_3)、术毕(T_4)时的局部脑氧饱和度(rScO_2)以及右侧大脑中动脉血流平均速度(V_(MCA))、搏动指数(PI)和阻力指数(RI)。结果与T_2时比较,T_0、T_1、T_3、T_4时两组患儿rScO_2和V_(MCA)明显升高(P0.05),PI和RI明显降低(P0.05)。T_0、T_1、T_3、T_4时L组rScO_2和V_(MCA)明显高于H组(P0.05)。结论 P_(ET)CO_2在40～45 mmHg时,患儿rScO_2和V_(MCA)高于P_(ET)CO_2在35～40 mmHg时,可改善脑氧供需平衡。     

经皮二氧化碳监测在肥胖患者行腹腔镜胃旁路术中的应用

目的研究肥胖患者行腹腔镜下胃旁路术中经皮二氧化碳分压(P_(TC)CO_2)监测评估PaCO_2的准确性和相关性。方法择期行腹腔镜下胃旁路术的患者22例,男9例,女13例,年龄19~55岁,体重86~160kg,BMI35kg/m~2,ASAⅠ或Ⅱ级,在麻醉后(气腹前)和气腹后30、60和120min时测量PaCO_2、P_(ET)CO_2和P_(TC)CO_2。并计算PaCO_2-P_(ET)CO_2和PaCO_2-P_(TC)CO_2的差值,采用Bland-Altman分析、相关与回归和确切概率法分析PaCO_2与P_(ET)CO_2、PaCO_2与P_(TC)CO_2的线性回归方程和一致性界限(LOA)。结果 1例男性患者因麻醉诱导时使用了去氧肾上腺素而被排除出本研究。余患者PaCO_2-P_(ET)CO_2的差值为(10.3±2.3)mm Hg,PaCO_2-P_(TC)CO_2的差值为(0.9±1.3)mm Hg。PaCO_2与P_(ET)CO_2之间的线性回归方程为P_(ET)CO_2=11.58~+0.57×PaCO_2(r2=0.64,P0.01);PaCO_2与P_(TC)CO_2之间的线性回归方程为P_(TC)CO_2=0.60~+0.97×PaCO_2(r2=0.89,P0.01),气腹后30、60和120min时P_(ET)CO_2和P_(TC)CO_2与PaCO_2具有明显相关性(P0.01)。PaCO_2-P_(ET)CO_2差值的95%LOA为(10.3±4.6)mm Hg;PaCO_2-P_(TC)CO_2差值的95%LOA为(0.9±2.6)mm Hg。结论肥胖患者行腹腔镜下胃旁路术中,P_(TC)CO_2比P_(ET)CO_2更精确地评估PaCO_2。     

老年人单肺通气时呼气末二氧化碳监测的可信度

目的 观察老年人单肺通气(OLV)麻醉时P_(ET)CO_2C_2和PaCO_2的相关性,以评定P_(ET)CO_2监测在老年人单肺通气麻醉的可信度.方法 37例老年肺部肿瘤患者,胸腔镜下行胸部肿瘤切除、活检或肿瘤根治术,采用静脉复合全麻,术中行OLV.记录麻醉前及OLV 30、60、90、120、180和240min时BP、HR、SpO_2、P_(ET)CO_2和动脉血气,计算氧合指数(PaO_2/FiO_2)、动脉-呼气末二氧化碳分压差(P_(a-ET)CO_2),及对应时间点P_(ET)CO_2和PaCO_2的相关性.结果 除OLV 180 min时点外,术中各时点PaCO_2与P_(ET)CO_2有较好的相关性.术中5例发生低氧血症.结论 老年人OLV麻醉中P_(ET)CO_2不能完全反映PaCO_2的变化,长时间OLV者需同时行血气分析,以保证老年人的安全.     

利多卡因气管内注药对腹腔镜手术患者眼内压的影响

目的观察利多卡因气管内注药对腹腔镜手术患者眼内压的影响。方法选择美国麻醉医师协会麻醉分级(ASA)Ⅰ~Ⅱ级、无眼部疾患的80例腹腔镜胆囊切除手术患者,随机分为利多卡因组(L组)和对照组(C组),每组各40例。L组患者麻醉诱导后在气管内喷注2%利多卡因2 ml,C组患者给予等量生理盐水。记录麻醉诱导前(T_0),诱导后3分钟(T_1),气管插管后1分钟(T_2),二氧化碳(CO_2)气腹后10分钟(T_3),气腹后30分钟(T_4),气腹结束后10分钟(T_5)不同时间点患者的眼内压(IOP)、平均动脉压(MAP)、心率(HR)及呼气末二氧化碳分压P_(ET)CO_2的变化。结果与T_0时比较,T_1时两组IOP、MAP及HR明显降低。与T_1时比较,T_2~T_4时两组IOP、MAP和HR明显升高(P0.05)。但L组T_2~T_4时I0P、MAP和HR升高幅度均明显低于C组(P0.05)。术中两组患者P_(ET)CO_2均在正常范围,两组比较差异无统计学意义(P0.05)。结论麻醉诱导后气管内注入利多卡因可有效减轻腹腔镜手术患者气管插管后和气腹后所致的I0P升高。     

目标导向液体治疗对妇科腹腔镜手术术中血流动力学及脑氧饱和度的影响

目的观察目标导向液体治疗(GDFT)对妇科腹腔镜手术术中患者血流动力学及脑氧饱和度(rSO2)的影响。方法选择择期全麻下行腹腔镜妇科肿瘤根治手术患者42例,年龄45~65岁,ASAⅠ或Ⅱ级,采用随机数字表法分为两组:传统液体治疗组(C组)和GDFT组(G组),每组21例。通过LiDCOrapid监测系统监测MAP、心输出量(CO)、心脏指数(CI)、每搏量变异度(SVV)。C组采用传统液体疗法;G组采用SVV指导下的GDFT,维持CI≥2.5 L·min^-1·m^-2。记录麻醉诱导前(T0)、麻醉诱导后(T1)、Trendelenburg体位后30 min(T2)、Trendelenburg体位后1 h(T3)及术毕(T4)时的HR、MAP、CO、CI、SVV、rSO2;记录术中总输液量、晶体液用量、胶体液用量、尿量、血管活性药物使用情况;检测患者术后2 h凝血功能及术后3个月肝肾功能。结果与C组比较,T3时G组HR明显加快(P<0.05),CI明显升高(P<0.05),T2、T3时G组CO明显升高(P<0.05),T1-T3时G组SVV明显降低(P<0.05);G组术中晶体用量[(1 519±472)ml vs(2 112±433)ml]和总输液量[(2 526±587)ml vs (2 745±582)ml]明显减少(P<0.05),胶体用量[(1 007±196)ml vs (633±189)ml]明显增加(P<0.05)。两组患者围术期rSO2、术中尿量、血管活性药物使用、术后2 h凝血功能、术后3个月肝肾功能差异无统计学意义。结论在SVV指导下的GDFT可减少术中总输液量,同时可稳定Trendelenburg体位下行腹腔镜妇科手术患者的血流动力学,且不影响rSO2。     

瑞芬太尼对单肺通气患者炎症反应和氧合功能的影响

目的 观察瑞芬太尼对单肺通气患者炎症反应和氧合功能的影响.方法 择期开胸手术行单肺通气患者30例,按照随机排列表分为生理盐水对照组(C组)和瑞芬太尼治疗组(R组),每组15例.两组患者在单肺通气前1 min(T1),单肺通气结束后3 min(T2)及其后30 min(T3)各时间点进行动脉血气分析及计算肺内分流率(Qs/Qt)和氧合指数值(PaO2/FiO2),并采取颈内静脉血测定细胞因子及炎性介质的活性.结果 同T1时相比:C组Qs/Qt在T2、T3时显著升高(P＜0.05)[(15.1±4.6)％vs.(11.5±3.4)％,(16.7±3.9)％vs.(11.5±3.4)％],而paO2/FiO2在T2、T3时显著下降(P ＜0.05)[(397 ±95) mm Hg vs.(471±69) mmHg,(384±78) mm Hg vs.(471±69) mmHg](1 mmHg=0.133 kPa);R组Qs/Qt在T2时显著升高(P＜0.05)[(14.5±2.3)％vs.( 11.8±2.5)％],PaO2/FiO2在T2时显著下降(P＜0.05)[(410±45) mm Hg vs.(465±50) mmHg].同T2时相比:R组Qs/Qt在T3时显著下降(P＜0.05)[(12.0±2.3)％vs.(14.5±2.3)％],而PaO2/FiO2显著升高(P＜0.05)[(460±45) mm Hg vs.(410±45) mmHg].组间比较:R组Qs/Qt在T3时较C组显著下降(P＜0.05)[(12.0±2.3)％vs.(16.7±3.9)％],而PaO2/FiO2显著升高(P＜0.05)[(460±45) mmHg vs.(384±78) mm Hg].两组中性粒细胞在T2、T3时显著升高(P＜0.05),R组超氧化物歧化酶(SOD)在T2、T3时显著高于C组(P＜0.05)[ (58±4) U/ml vs.(53±7) U/ml,(57±5) U/ml vs.(50±9) U/ml],而丙二醛(MDA)、细胞间黏附分子-1 (ICAM-1)显著低于C组(P＜0.05)；R组肿瘤坏死因子-α(TNF-α)在T3时显著低于C组(P＜0.05).相关分析表明:TNF-α和ICAM-1,PaO2/FiO2和SOD,Qs/Qt和MDA有一定的相关性(P＜0.05).结论 瑞芬太尼对单肺通气患者炎症反应和氧合功能具有一定的保护作用.     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.