老年骨质疏松性胸腰椎压缩骨折的特征与漏诊原因分析

目的总结老年骨质疏松性胸腰椎压缩骨折的临床特点,分析漏诊原因。方法回顾性分析自2013-01—2016-11诊治的老年骨质疏松性椎体压缩骨折631例,分析骨折患者临床症状,以及年龄、性别、骨折类型、骨折部位与骨折漏诊率的相关性。结果本组漏诊178例,漏诊率28.2%。骨折漏诊率与性别无明显相关性(Z=1.581,P=0.218)。胸椎骨折、胸腰椎骨折、腰椎骨折漏诊率差异有统计学意义(Z=86.140,P0.001),且胸椎骨折漏诊率最高,腰椎骨折漏诊率最低。楔形骨折、双凹陷型骨折、塌陷压扁型骨折漏诊率差异有统计学意义(Z=273.589,P0.001),双凹陷型骨折漏诊率最高,塌陷压扁型骨折次之,楔形骨折漏诊率最低。55~64岁、65~74岁、75~84岁、≥85岁年龄段骨折漏诊率差异有统计学意义(Z=32.730,P0.001),且年龄越大漏诊率越高。结论重视患者症状、体征,结合X线、CT、MRI检查可降低老年骨质疏松性胸腰椎压缩骨折漏诊率。     

PVP治疗伴远隔部位疼痛的骨质疏松性椎体压缩骨折

目的分析经皮椎体成形术(Percutaneous vertebroplasty,PVP)治疗伴远隔部位疼痛的骨质疏松性椎体压缩骨折的临床疗效。方法回顾性分析自2016-02—2019-10采用PVP治疗的34例伴远隔部位疼痛的骨质疏松性椎体压缩骨折,比较术前与末次随访时疼痛VAS评分、ODI指数。结果 34例均顺利完成手术并获得完整随访,随访时间6～15个月,平均11.7个月。术后共出现9例骨水泥渗漏,未出现神经、血管损伤及再骨折等并发症。末次随访时疼痛VAS评分、ODI指数较术前明显降低,差异有统计学意义(P0.05)。结论远隔部位疼痛是骨质疏松性椎体压缩骨折的常见症状,以下腰部、臀部及髂嵴多见;PVP能够有效缓解骨质疏松性椎体压缩骨折患者的远隔部位疼痛,且不会导致严重并发症,值得在临床推广。     

骨质疏松性椎体压缩骨折在退变性脊柱侧凸的分布及危险因素

 目的 总结骨质疏松性椎体压缩骨折在退变性脊柱侧凸中分布的规律性,分析退变性脊柱侧凸患者发生椎 体压缩骨折的危险因素。方法 回顾性分析2004年7月至2012年7月治疗136例退变性脊柱侧凸患者资料,根据术前是 否发生骨质疏松性椎体压缩骨折分为骨折组和无骨折组。骨折组34例,男9例,女25例;年龄(71.7±1.7)岁。无骨折组 102例,男23例,女79例;年龄(63.3±6.7)岁。采用视觉模拟评分(visual analogue scale, VAS)评估胸背部疼痛程度,采 用双能X线骨密度仪测定骨密度T值,测量侧凸Cobb角,观察侧凸范围内骨桥发生情况。采用二分类Logistic逐步回归分析方 法筛选出骨折发生的危险因素。结果 骨折组发生T₁₁骨折3例,T₁₂骨折12例,L₁骨折15例 ,T₁₂及L₁两个椎体骨折4例。 无骨折组平均年龄低于骨折组(t=17.20,P<0.001),两组的性别组成并无差异(χ²=0.218,P=0.641),胸背部 疼痛的VAS评分小于骨折组(t=9.30,P< 0.001),侧凸Cobb角与骨折组相比无差异(t=1.84,P=0.08),骨质疏松的严重程度 低于骨折组(t=5.63,P<0.001),骨桥发生率低于骨折组(χ²=12.333,P< 0.001)。Logistic回归分析显示外伤 史(OR=1.36;95%CI,1.09～2.11)、骨桥形成(OR=3.31;95%CI,2.10～5.38)、骨质疏松(OR=2.45;95%CI,1.58～4.36) 会增加退变性脊柱侧凸患者发生骨质疏松性椎体压缩骨折的机会。结论 在退变性脊柱侧凸患者中,骨质疏松性椎体压缩骨折好 发于胸腰段椎体,外伤 史、骨质疏松以及侧凸范围内骨桥形成是骨折发生的危险因素。     

磁共振成像与核素骨显像对骨质疏松性椎体骨折诊断的比较

目的:比较分析磁共振成像(MRI)与核素骨显像对胸腰椎椎体骨质疏松性骨折诊断的敏感性及特异性。方法:24例(66个节段)胸腰椎骨质疏松性椎体骨折患者,分别行全身核素骨显像和脊柱MRI检查,比较两种方法对椎体发生骨折的显示情况。结果:以受累椎体个数为统计单位,在胸腰椎范围内,共66个椎体确定为责任节段,行椎体后凸成形术;MRI诊断60个节段,核素骨显像诊断58个节段,将两者的诊断个数进行Kappa检验,两者一致性较高,有统计学意义(Kappa=0.72,P=0.000)。结论:在显示骨质疏松性椎体压缩骨折方面,核素骨显像与MRI具有较高的一致性,可作为诊断骨质疏松性椎体骨折责任节段的有效辅助检查方式。     

CT值对强直性脊柱炎患者骨质疏松的评估

目的:利用腰椎CT值来评估强直性脊柱炎患者骨质疏松以及骨质疏松性椎体骨折和螺钉松动的情况。方法:回顾性分析2002年1月~2017年12月在我院住院并手术的27例强直性脊柱炎患者骨密度资料。双能X线骨密度测定法(dualenergy X-ray absorptiometry,DXA)检查结果T值>-1为骨量正常,T值-2.5^-1为骨量减少,T值<-2.5为骨质疏松。L1椎体平均CT值<100HU诊断骨质疏松,100~160HU之间为骨量减少,160HU以上为骨量正常。用SPSS统计软件进行分析,经Kappa检验评估以及Mann-Whitney U检验比较DXA和CT值评估强直性脊柱炎患者中骨质疏松以及骨质疏松性椎体骨折和螺钉松动情况。结果:27例患者中,使用传统DXA方法测量骨质疏松患者16例,骨量减少患者6例,骨量正常患者5例;用CT值测量骨质疏松患者16例,骨量减少患者9例,骨量正常患者2例,经Kappa检验两者一致性差,两种方法评估骨质疏松存在差异,通过Mann-Whitney U检验比较骨质疏松的常见并发症骨质疏松性椎体骨折,发现CT值评估骨量情况的患者在椎体骨折组和非骨折组分布存在差异性(CT值诊断为骨质疏松的患者更易同时并发骨质疏松性骨折)(P=0.009),而DXA评估骨量情况的患者在椎体骨折组以及非骨折组分部无统计学差异(P=0.095)。CT值诊断为骨质疏松的强直性脊柱炎患者在螺钉松动组以及非螺钉松动组分布无显著性差异(P=0.272),DXA诊断骨质疏松的强直性脊柱炎患者在螺钉松动组以及非螺钉松动组分布无显著性差异(P=0.610)。结论:CT值和DXA方法测量强直性脊柱炎患者骨密度情况一致性差,在骨质疏松性椎体骨折中应用CT值评估强直性脊柱炎患者骨质疏松情况比传统DXA有一定的优势,但本身也存在一定局限性。     

经皮椎体成形术治疗胸腰段骨质疏松性椎体压缩骨折伴远隔部位疼痛

目的比较经皮椎体成形术(PVP)治疗伴或不伴远隔部位疼痛胸腰段骨质疏松性椎体压缩骨折的临床疗效。方法回顾性分析自2015-01—2018-09采用PVP治疗的79例骨质疏松性椎体压缩骨折,28例术前伴远隔部位疼痛(观察组),51例术前无伴远隔部位疼痛(对照组)。比较2组骨折类型、骨折程度,末次随访时疼痛VAS评分、ODI指数,比较观察组手术前后远隔部位疼痛VAS评分。结果74例获得随访,随访时间平均16.76(6~42)个月,5例失访。观察组出现5例骨水泥渗漏,对照组出现11例骨水泥渗漏。末次随访时观察组与对照组疼痛VAS评分、ODI指数比较差异无统计学意义(P>0.05)。末次随访时观察组远隔部位疼痛VAS评分较术前低,差异有统计学意义(P<0.05)。观察组垂直压缩骨折率较对照组高,重度骨折率较对照组高,差异有统计学意义(P<0.05)。结论PVP可有效缓解胸腰段骨质疏松性椎体压缩骨折引起的远隔部位疼痛,胸腰段椎体重度、垂直压缩形骨折应排除远隔部位疼痛的存在。     

球囊扩张椎体后凸成形术治疗骨质疏松性椎体骨折后骨坏死

目的 探讨球囊扩张椎体后凸成形术治疗骨质疏松性椎体骨折后骨坏死的效果.方法 回顾性分析2005年1月至2008年1月收治的31例骨质疏松性椎体骨折后骨坏死患者的临床资料.其中男性13例,女性18例;年龄57～84岁,平均71岁;背部疼痛病史1个月～lO年.术前行x线片、CT、MRI等影像学检查.患者均行球囊扩张椎体后凸成形术治疗,术中取椎体内组织进行术后常规病理学检查.测量并比较术前、术后1 d及末次随访时站立位X线片伤椎前缘相对高度.采用疼痛视觉模拟评分(VAS)及Oswestry功能障碍指数(ODI)评价手术疗效.结果 患者均获随访,随访时间18～48个月,平均27个月.术前与术后1 d伤椎前缘相对高度分别为(34.7±3.1)%和(71.4±2.3)%,差异有统计学意义(P＜0.05);末次随访时为(70.2±2.5)%,与术后1 d相比差异无统计学意义(P＞0.05).术前VAS及ODI评分分别为8.7±0.4和89.1±2.7,术后1 d分别为2.3±0.7和31.7±3.1,手术前后差异均有统计学意义(P＜0.05);末次随访时分别为1.9±0.2和29.1±2.7,与术后1 d相比差异无统计学意义(P＞0.05).所有指标数据末次随访时与术前比较,差异均有统计学意义(P＜0.05).2例发生骨水泥渗漏,未出现临床症状.1例术后发生其他椎体骨折.结论 球囊扩张椎体后凸成形术是治疗骨质疏松性椎体骨折后骨坏死的有效方法.     

经皮椎体增强术治疗骨质疏松性压缩性骨折远处疼痛的价值

目的 分析骨质疏松性压缩性骨折椎(责任椎)远处疼痛的发生率,评估经皮椎体增强术治疗责任椎远处疼痛的价值. 方法 回顾性研究2006年12月至2008年8月采用椎体增强术(经皮椎体成形术或经皮后凸成形术)治疗的104例骨质疏松性压缩性骨折患者术前出现责任椎远处疼痛的部位和程度,手术前、后疼痛程度和活动能力评分分别采用视觉模拟法(VAS)和口常生活能力法(ADL)评分. 结果 104例患者术前共48例(46.2%)发生责任椎远处疼痛,主要分布存骶尾部和臀部(26.0%),其次在腹部和剑突下(10.6%),再次在胸廓外侧、肋骨和胸前(9.6%).患者总体VAS评分从术前(8.9±0.8)分下降至术后(2.9±1.4)分,筹异有统计学意义(t=37.410,P=0.000);ADL评分从术前(4.1±0.6)分下降争术后(2.0±0.7)分,差异有统计学意义(t=25.331,P=0.000).其中发生责任椎远处疼痛患者VAS评分从术前(8.8±0.9)分下降至术后(2.8±1.5)分,差异有统计学意义(t=23.722,P=0.000);ADL评分从术前(4.2±0.7)分下降至术后(2.0±0.7)分,差异有统计学意义(t=15.373,P=0.000). 结论责任椎远处疼痛足骨质疏松性压缩性骨折常见的临床表现,是椎体源性的牵涉痛,主要发生在骶尾部和臀部.椎体增强术可有效缓解由椎体骨折导致的责任椎远处疼痛.     

经皮椎体成形术治疗老年性骨质疏松性脊柱骨折

目的探讨经皮椎体成形术(percutaneous vertebroplasty,PVP)对老年骨质疏松性脊柱骨折的治疗价值. 方法10例(11个椎体)老年骨质疏松性脊柱骨折采用PVP治疗,观察PVP后患者病情的改善情况. 结果 10例行PVP后症状均显著缓解,腰背痛疼痛视觉模拟评分(visual analogue pain scale,VAS)由术前的(9.4±1.8)分下降到(1.1±0.7)分(t=13.590,P=0.000).无临床并发症发生.随访4～14个月,平均6.4月,1例T11骨折者又出现L1骨折,未再治疗,余9例疼痛无复发. 结论 PVP对老年性骨质疏松性脊柱骨折是一种较好的微创治疗方法,其止痛效果尤为显著.     

SPECT-CT与MRI对确定骨质疏松性椎体压缩骨折疼痛责任椎体的价值比较

目的 :探讨单光子发射计算机断层摄影术联合同机CT扫描图像融合技术(single photon emission computed tomography-computed tomography,SPECT-CT)与磁共振成像(MRI)在确定骨质疏松性椎体压缩骨折(osteoporotic vertebral compression fractures,OVCFs)疼痛责任椎体的一致性。方法 :选取2015年12月~2016年12月期间吉林大学中日联谊医院46例OVCFs患者,其中28例患者病程在3周之内,属于急性期骨折;18例病程在3周以上,属于非急性骨折。患者均行SPECT-CT和MRI检查,根据MRI及SPECT-CT共同确定疼痛责任椎体,行PKP术,采用疼痛视觉模拟评分法(visual analogue score,VAS)评估手术治疗效果,使用配对样本t检验分析治疗前后VAS评分,从而判定责任椎体的准确性,应用Kappa检验和Mc Nemar检验分析两种检查法的一致性和差异性,并计算SPECT-CT诊断的准确性指标。结果:46例患者中,MRI检查出OVCFs的责任节段79个,SPECT-CT检查出责任节段83个,最终77个椎体行PKP手术治疗。术前VAS评分8.33±2.12分,术后3天评分0.89±1.86分,术后1个月评分0.30±0.94分,较术前明显改善(P0.05)。急性期28例患者共36个椎体行PKP手术治疗,MRI检查符合诊断标准的37个节段,SPECT-CT检查36个节段。非急性期18例患者共41个椎体行PKP手术治疗,MRI检查出42个节段,SPECT-CT检查出47个节段。分别将骨折不同时期的MRI和SPECT-CT的诊断结果进行Kappa检验,结果提示结果提示急性期两种检查方法高度一致(Kappa=0.943,P0.05),非急性期一致性一般(Kappa=0.734,P0.05)。对比不同时期骨折的SPECT-CT与MRI检查结果的符合性采用Mc Nemar检验,结果提示两种检验方法之间的差异不具有统计学意义(P0.05)。此外,骨折的不同时期尤其是急性期,SPECT-CT与MRI的诊断性试验指标一致性较高。结论:SPECT-CT在骨质疏松性椎体压缩骨折的定位、定性上与MRI具有较高的一致性,尤其对于急性期骨折的患者,其具有较好的临床应用价值。     

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 Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

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.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

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.     

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.     

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.