颈椎间盘与纵韧带损伤的诊断及治疗

目的 探讨颈椎间盘和纵韧带损伤的诊断与治疗方法。方法回顾性分析2001至2005年63例颈椎间盘与纵韧带损伤患者的X线片和MRI表现,根据是否合并脊髓损伤及椎间不稳,早期采取不同治疗方法。早期手术治疗54例,早期颈托和（或）石膏颈围保守治疗9例。结果61例患者获得随访,随访时间6～41个月,平均16个月。8例脊髓完全性损伤患者术后2例神经功能获得改善,39例脊髓不完全性损伤患者术后31例神经功能获得改善。4例保守治疗4～6周后存在颈椎不稳而行颈椎前路椎间盘切除植骨融合术,2例长期颈部疼痛,1例伤后3年出现脊髓压迫症而行前路减压植骨融合术。结论MRI检查是颈椎间盘和纵韧带损伤的最佳诊断手段,早期颈椎前路减压植骨内固定术是治疗颈椎间盘与纵韧带损伤的重要方法。     

内窥镜下前路颈椎间盘切除及椎间融合术

目的 观察内窥镜下前路颈椎间盘切除及椎间盘切除及椎间融合术的临床疗效。方法 自2002年10月，对26例患者实施内窥镜下前路颈椎间盘切除及椎间融合术。其中获得3个月以上随访者16例，男12例，女4例；年龄23～65，平均53.2岁。颈椎外伤合并椎间盘突出症3例，脊髓型颈椎病8例，孤立性颈椎后纵韧带骨化2例，神经根型颈椎病3例。单间隙4例，双间隙12例。病变节段：C3.42个，C4.511个，C5.613个，C6.72个。术前ADL评分平均7.2分。于内窥镜下施行手术，彻底减压后植入PEEK椎间融合器。结果 手术时间50～150min，平均120min。术中出血量40～140ml，平均110ml。无一例发生术中并发症，无一例改为开放手术。术后无咽喉部刺激症状，切口内出血1例。16例患者随访3～8个月，平均6.5个月。术后ADL评分平均13.1分，ALD改善率为60.2%。结论 内窥镜下实施前路颈椎间盘切除及椎间融合术具有切口小、组织损伤轻、手术操作安全等优点。适用于C3.4～C5.6区域内的颈椎间盘突出症、脊髓型颈椎病、神经根型颈椎病、位于椎间隙的孤立性后纵韧带骨化症、颈椎外伤导致的单词隙椎间盘损伤合并颈椎不稳者。     

颈椎病患者后纵韧带与硬脊膜粘连的判断

目的回顾性评估经前路手术证实的脊髓型颈椎病后纵韧带与硬脊膜粘连特点。方法2005年12月至2007年1月，治疗18例脊髓型颈椎病患者，男11例，女7例；年龄55～72岁，平均65．4岁。术前行颈椎CT与MR检查，未发现有后纵韧带及硬脊膜骨化。二节段颈椎间盘突出12例（66．7％），三节段颈椎间盘突出6例（33.3％）。二节段手术方法为单椎节椎体次全切除＋钛网（或髂骨）＋颈前路钢板固定；三节段手术方法为单椎节椎体次全切除植骨内固定，另一病变节段用颈椎cage植入融合。手术中证实存在后纵韧带与硬脊膜粘连，术中以“漂浮”方法处理后纵韧带与硬脊膜粘连。应用配对计数资料Kappa系数检验两种影像学提示存在后纵韧带和硬脊膜粘连的吻合度。结果全部病例手术后神经功能均有不同程度改善，按JOA评分法，术前平均9．6分，术后平均12．1分。4例术中损伤硬脊膜未直接修补，术后发生脑脊液漏，经适当加压处理，伤口均获得愈合。颈后纵韧带与硬脊膜粘连的CT横断位扫描示椎间盘与硬脊膜接触不光滑，有毛刺现象；MRI示后纵韧带增厚，粘连处硬膜下间隙与邻近间隙不对称。统计分析结果Kappa系数=0．40，P〈0．05，表明CT与MRI显示后纵韧带和硬脊膜粘连情况时，两者比较差异有统计学意义。结论脊髓型颈椎病前路减压术前MR检查能判断后纵韧带与硬脊膜粘连，其准确率优于CT扫描。手术中采用“漂浮”方法能有效处理粘连病变。     

切除与不切除后纵韧带颈椎减压术后的MRI观察

目的:观察颈前路减压切除与不切除后纵韧带术后的MRI表现。方法:回顾性分析22例行颈前路减压患者的术后MRI检查资料,其中行颈椎后纵韧带切除者12例,未行切除者10例。观察脊髓形态,测量脊髓矢状径,并进行比较。结果:随访12~36个月,MRI显示后纵韧带切除组术后与术前脊髓矢状径差值大于未行后纵韧带切除组(P<0.01)。结论:颈椎前路切骨减压时行增生后纵韧带切除可使病变节段减压更加彻底,有利于脊髓型颈椎病患者脊髓形态的恢复。     

颈椎间盘突出症合并后纵韧带肥厚的手术治疗

目的：探讨颈椎间盘突出症合并后纵韧带肥厚病例的手术治疗问题。方法：回顾分析了经前路手术治疗的颈椎间盘突出症合并后纵韧带肥厚病例８３例,占同期前路手术治疗颈椎间盘突出症病例（３７６例）的２２．０７％。重点介绍了如何选择手术适应症,特别是术中如何判定是否应该切除后纵韧带,手术技巧及注意事项等。结果：全组术后经３～５９个月,平均２０．６个月随访,优良率达９１．５７％。切除之后纵韧带经病理检查证实有增生、肥厚、纤维化等。结论：对典型的颈椎间盘突出症需经前路手术,合并有后纵韧带肥厚者,应在切除突出间盘的同时切除后纵韧带,以使颈髓完全解除束缚,疗效更加趋于完善。     

颈椎过伸性损伤伴多节段继发性椎管狭窄的MRI特点与颈后路手术疗效观察

目的分析颈椎过伸性损伤伴多节段继发性椎管狭窄的MRI特点并探讨颈后路手术治疗后的临床疗效。方法回顾性分析自2010-06—2018-12诊治的47例伴有多节段继发性椎管狭窄的无骨折脱位型颈椎过伸性损伤,其中颈椎间盘突出26例(颈椎间盘突出组),后纵韧带骨化14例(后纵韧带骨化组),颈椎病7例(颈椎病组)。比较各组术前与末次随访时JOA评分、ASIA评分、Frankel等级。结果47例均获得随访,随访时间平均12(6~18)个月。颈椎间盘突出组、后纵韧带骨化组、颈椎病组术后JOA评分、ASIA评分、Frankel等级较术前均显著改善,差异有统计学意义(P<0.05)。结论对伴有多节段继发性椎管狭窄的颈椎过伸性损伤患者,术前根据患者的MRI特点,制定个性化颈后路治疗方案,可以获得较为满意的治疗效果。     

颈椎前纵韧带损伤的诊断与治疗

目的 探讨颈椎前纵韧带损伤的诊断与治疗.方法 2001年3月至2003年7月经影像学证实为前纵韧带损伤的患者46例.患者均在伤后3 h～3 d内摄颈椎正、侧位X线片并行MRI检查.颈椎椎前阴影增宽35例,椎体不稳征象14例.颈椎MRI T<,1>加权像表现为前纵韧带呈灰色或灰白色信号,部分可见连续性中断、增厚;T<,2>加权像表现为椎体前缘增厚的片状纵行不均匀高信号,边界不清晰,部分可见高信号掀起、连续性中断.19例合并脊髓损伤的患者行早期手术治疗.27例单纯颈部疼痛患者中,早期前路手术治疗6例,颈围石膏固定5例,颈托固定16例. 结果 45例患者获6～41个月(平均16.7个月)随访.5例脊髓完全性损伤患者术后有2例转为不完全性损伤,14例脊髓不完全损伤患者术后有10例获得不同程度的好转.21例单纯颈部疼痛患者中,早期手术的6例无神经症状患者随访时未发生颈椎后凸畸形及颈部慢性疼痛症状;21例早期保守治疗的患者中,7例伤后4～6周因存在颈椎不稳征象而行颈椎前路手术,2例伤后2～3年因损伤节段椎间盘退变突出压迫脊髓而行前路减压植骨内固定术,3例有慢性颈部疼痛不适,余8例患者无特殊不适主诉,另1例失访.结论 MRI检查是诊断颈椎前纵韧带损伤最有价值的方法.合并脊髓受压征象或椎间严重不稳的颈椎前纵韧带损伤,可早期行减压融合术;不伴脊髓损伤的颈椎前纵韧带合并椎间盘损伤,可考虑早期行前路椎间盘切除融合术.     

颈椎前路手术中后纵韧带切除的探讨

目的：探讨颈椎前路手术后纵韧带切除的指征、方法和注意事项，方法：对2000年4月－2002年4月后纵韧带切除的50例颈椎前路手术患者的临床资料及手术治疗结果进行回顾性分析。结果：42例获得6个月以上随访，根据JOA评分标准，平均改善率为70．5％，优14例，良16例，中9例，差3例，结论：后纵韧带退变肥厚、后纵韧带骨化或硬膜外型颈椎间盘脱出压迫颈髓时，行颈椎前路手术时应切除后纵韧带，彻底减压。     

Bryan颈人工椎间盘置换术失败原因分析

目的 对Bryan颈人工椎间盘置换术治疗颈椎病的失败原因进行分析.方法 2004年10月至2007年10月,采用Bryan颈人工椎间盘对48例颈椎病患者的56个椎间盘进行治疗,其中单节段40例,双节段8例.术后随访2～38个月,平均18个月.手术失败4例,男1例,女3例;年龄分别为42、51、40、49岁.患者均为经6周的保守治疗无效后行Bryan颈人工椎间盘置换.结果 1例全麻后在用胶带固定患者体位的过程中造成对臂丛的过度牵拉,术后双上肢肌力下降到2～3级.1例术前CT及MRI显示C4～C6水平后纵韧带骨化,其中C4,5节段骨桥形成,向后方压迫脊髓;手术切除部分骨化后纵韧带,使之漂浮;术后患者症状无改善,并出现锥体束征阳性,复查CT及MRI示存在骨化后纵韧带压迫脊髓.1例术前MRI显示C4-5椎间盘突出,椎管前后径约为5 mm,C4,5水平脊髓变性;术中向外侧减压时致椎管内静脉破裂,出血影响术野;术后左侧肢体肌力下降至0级.1例术后1年发现假体后方异位骨化,但不影响关节活动.结论 臂丛损伤、减压不彻底、术中椎管内静脉出血和异位骨化可能是引起颈椎人工椎间盘置换术失败的主要原因.     

MRI诊断胸腰椎骨折后柱韧带复合体损伤的可靠性研究

目的 探讨MRI诊断胸腰椎骨折患者后柱韧带复合体（posterior ligamentous complex，PLC）损伤的真实性与可靠性。方法2004年12月至2005年6月，胸腰椎骨折患者82例，男54例，女28例；年龄14-75岁，平均45．8岁；高处坠落伤47例，交通事故伤15例，重物压伤7例，其他损伤13例。82例患者中单节段骨折65例，双节段骨折16例，三节段骨折1例（有连续两个节段骨折），损伤节段共100处。术前对胸腰椎骨折患者进行MR检查，评价PLC损伤情况。术中探查并记录PLC损伤程度。分析MRI诊断PLC各部分损伤的灵敏度、特异度和符合率。结果 MRI诊断棘问韧带、棘上韧带和黄韧带损伤的灵敏度分别为92.3％、95.2％和93.3％，特异度分别为98．6％、98．7％和100．0％，符合率分别为97．0％、98．0％和99．0％。MRI显示小关节囊损伤22例，术中探查小关节囊损伤21例。MR检查PLC损伤的整体符合率Kappa值为0．786。结论 MRI是诊断PLC损伤的有效方法，具有灵敏度、特异度及符合率高的特点，与术中所见高度一致。     

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.     

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.     

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.     

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.