术前活动度对人工全膝关节置换术后功能影响的观察

目的回顾性分析患者手术前的活动度对人工全膝关节置换(TKA)术后功能的影响。方法随访2000年1月—2003年12月在我科行TKA的患者65例(97膝),年龄64．8±9．9岁(35～85岁)。其中骨性关节炎55例(81膝),类风湿关节炎10例(16膝)。单膝置换33例,双膝同时置换32例。所有患者按术前膝关节活动度数(ROM)分成两组,≤90°(5°～90°)49膝,>90°(95°～140°)48膝。对两组患者进行疗效(最大屈膝度、活动度、KSS评分及功能评分)对比。所有患者均采用Scorpio后稳定型骨水泥固定的假体,均为初期置换,全部手术由同一组医师完成。术后3 d在同一康复师指导下行患肢CPM及主动功能锻炼至出院。结果平均随访时间29个月(10～44个月)。所有膝关节的活动度从术前的平均84．2°(5°～140°)提高到术后的平均101．6°(40°～140°) (P=0．000);而最大屈膝度数术前的平均103．5°(25°～140°)与术后的平均101．6°(40°～140°)无显著差异(P=0．439);KSS膝关节评分从术前平均19．5分(-24～62分)提高到术后平均78．8分(50～95分)(P=0．000)。所有患者的总满意度为93．8％(61／65)。两个分组比较,ROM≤90°的膝关节ROM及最大屈膝度术后均较术前有提高,而ROM>90°的膝关节平均最大屈膝度术后反而下降。没有翻修及深部感染。结论(1)在影响TKA术后膝关节功能的多种因素中,手术技术是关键因素。(2)在其他因素相同的情况下,术前膝关节的活动度对TKA术后的功能也有很大的影响,术前活动度大的膝关节比那些术前活动度小的膝关节术后能获得更好的功能。     

早期严重胫骨平台骨折和开放复位内固定后继发关节炎施行全膝置换术

目的　探讨采用全膝关节置换治疗早期严重的胫骨平台骨折及骨折后创伤性膝关节炎的临床效果。方法　16例严重的胫骨平台骨折和继发创伤性膝关节炎患者行全膝关节置换术,并进行临床观察。结果　平均随访 32个月(12~62个月)。根据Martin评分,从术前平均 32分 (10 ~59分 )提高到随访时平均 80分(30~92分),功能评分从术前平均 46分(25~69分)提高到随访时平均 79分 (40 ~100分 )。膝活动度从术前的平均 58°增加到随访时的平均 88°。最后功能评价:优 8例(6例为早期行全膝关节置换手术, 2例为继发性创伤关节炎者),良 7例,差 1例。结论　严重的胫骨平台骨折和手术后继发创伤性膝关节炎采用全膝置换可挽救或明显改善功能,缓解疼痛。严重的胫骨平台骨折早期全膝关节置换临床效果优于继发创伤性膝关节炎。     

人工全膝关节表面置换术治疗重症膝关节病

目的　探讨人工全膝表面置换术 (TKA)治疗重症膝关节病的疗效。方法　采用TKA共治疗 21例 24膝,其中晚期骨性关节炎 15例 17膝,类风湿关节炎 4例 5膝,全膝关节结核 2例 2膝。按TKA原则施术,重建膝关节负重力线,截骨达到伸屈间隙相等,维护软组织平衡,保持髌骨中置位,获取膝关节充分活动度。结果　平均随访 2 5年,膝关节平均活动度由术前的 58°(30°~100°)改善到 96°(60°~120°),疼痛、跛行明显改善,无感染。结论　对疼痛、畸形、明显影响功能、年龄在 60岁以上的重症膝关节病患者选择TKA治疗,疗效满意。     

膝关节外翻畸形的人工全膝关节置换术

目的探讨膝关节外翻畸形患者行人工全膝关节置换术(TKA)的手术方法和临床效果。方法对1996年1月至2004年8月74例87个膝关节外翻畸形TKA手术进行回顾分析。患者男11例,女63例,平均年龄63岁(26~80岁);股胫角(股骨和胫骨解剖轴线的夹角)平均为21·59°(12°~40°);应用后稳定型假体,采用髌旁内侧入路、常规截骨加单纯外侧软组织松解方法。随访检查膝关节活动度、X线外翻角度及KSS评分以评价手术效果。结果术后评价随访时间33·8个月(5个月~9年),根据膝关节活动度数及KSS评分评估关节功能情况。膝关节平均活动度为112·4°(80°~130°),KSS评分平均为81·7分(71~93分),比术前提高了59分;功能评分平均为86·3分,比术前提高了59·8分。所有膝关节在行TKA后外翻畸形基本得到矫正,随访时外翻度数(股胫角)平均为8·7°(0°~11°),较术前有明显改善。随访时1例患者有膝关节轻度不稳症状,1例术前严重髌脱位患者术后髌骨存在半脱位,其余正常。结论对于膝关节外翻畸形患者,采用髌旁内侧入路、常规截骨加单纯外侧软组织松解以及安装后稳定型假体的方法,可取得比较满意的临床效果。     

全膝关节置换治疗创伤后膝僵硬畸形

目的探讨全膝关节置换术(TKA)对创伤后膝僵硬畸形的治疗效果。方法对13例创伤后膝僵硬畸形患者采用TKA手术治疗,对比分析手术前后关节活动度范围以及膝关节HSS评分变化。结果 13例患者均获随访,时间3个月～3年6个月。HSS评分由术前的27～47(36±3.8)分提高到术后的80～92(86±3)分,关节活动范围由术前的5°～35°(20±3.5°)提高到术后的85°～100°(90°±5°),术前术后比较均有明显改善(P<0.05)。结论创伤后膝僵硬畸形采取TKA治疗可以明显改善关节活动范围,缓解症状,恢复功能,疗效满意。     

膝关节类风湿关节炎伴重度屈曲畸形患者关节置换术后的中长期随访

目的分析膝关节类风湿关节炎(RA)伴重度屈曲畸形行全膝关节置换术(TKA)中长期随访结果,探讨其关键的手术技术和康复措施。方法 1998年1月至2005年12月,18例RA伴重度屈曲畸形患者32膝行TKA,平均年龄38.8岁。RA病程14.2年,畸形时间6.5年;术前畸形67.5°,活动度20.3°,合并内翻畸形3例,外翻11例;术前股四头肌肌力3级7例,4级11例;HSS评分21.1分。术前锻炼股四头肌肌力,术中软组织松解及增加截骨,术后伸直支具及伸膝锻炼。术后1、2、3、6、12个月及以后每年随访,评价关节活动度、生存率、HSS评分等。结果 16例患者获得随访,5～10年随访10例18膝,10年以上6例11膝。最后一次随访,膝关节屈曲畸形3.7°,活动度103.2°,HSS评分为81.4分,与术前相比差异有统计学意义(P<0.05)。2膝翻修,假体生存率93.1%。无感染及侧副韧带损伤。结论通过加强术前术后股四头肌功能训练,术中软组织松解及增加股骨远端截骨,膝关节RA伴重度屈曲畸形患者TKA术后中长期随访效果满意。     

旋转铰链型人工膝关节临床应用近期疗效观察

目的探讨旋转铰链型人工膝关节临床应用的近期疗效。方法2002年7月～2005年4月，应用旋转铰链型人工膝关节假体进行全膝关节置换术治疗膝关节严重畸形和不稳定17例17膝。其中男8例，女9例；年龄41～79岁，平均59岁。左侧10例，右侧7例。患者均因膝关节疼痛人院，病程1～7年。其中骨性关节炎10例，类风湿性关节炎5例，左股骨骨折术后创伤性关节炎1例，左胫骨平台骨折术后创伤性关节炎合并前交叉韧带、内侧半月板损伤及内侧侧副韧带断裂1例。术前HSS（hospital for special surgery）评分36-58分，平均48．6分；术前膝关节屈曲活动度21～80°，平均57．4°。结果术后患者均获随访7个月～3年，平均23．6个月。无下肢静脉血栓形成或肺栓塞，无腓总神经麻痹、骨折或伸膝装置断裂等并发症发生。1例患者术后3个月出现迟发感染，再次手术取出假体，应用抗生素骨水泥间隔行膝关节旷置待二期置换。其余16例最后随访时，HSS评分78～98分，平均91．1分，较术前平均增加45．5分，且差异有统计学意义（P〈0．05）；术后2周，膝关节屈曲活动度为75～100°，平均85．2°，最后随访时膝关节屈曲活动度为85～123°，平均108．3°，与术前比较差异有统计学意义（P〈0．05）。结论旋转铰链型人工膝关节置换术近期疗效肯定，远期疗效尚待进一步随访。     

国产人工膝关节系统初步应用的经验总结

目的总结初步使用国产TC-Dynamic人工膝关节系统的临床效果和手术经验。方法本组使用国产TC—Dynamic人工膝关节行全膝关节置换术（TKA）40例60膝，术前膝关节外科学会评分（KSS）的膝评分平均为16．28分（-32～47分），功能评分平均为18．36分（-20～60分），膝关节活动度（ROM）平均为79．22&#176;（20&#176;～145&#176;）。结果36例52膝术后获得平均随访时间为20．41m（1．5～40m），随访时KSS膝评分平均为84．88分（70～95分），功能评分平均为80．58分（55～90分），ROM平均为110．48&#176;（85&#176;～140&#176;）。所有随访患者术后X线片均示下肢力线良好，假体位置满意，无透亮线及任何松动迹象。结论使用国产TC—Dynamic人工膝关节假体的TKA手术临床效果满意。手术操作简便，截骨量较少，如果手术配套器械的设计和制作工艺能够进一步改良和提高，则更利于临床应用。     

人工全膝表面关节置换治疗骨性膝关节炎47例

目的　分析总结人工全膝表面关节置换治疗骨性膝关节炎的临床效果及经验。方法　对 4 7例 5 3膝的骨性膝关节炎病例行人工膝关节置换术 ,单膝关节置换 4 1例 ,双膝关节置换 6例 1 2膝。应用后方稳定型假体 2 1例 2 5个膝关节 ,保留后交叉韧带型假体 2 6例 2 8个膝关节。结果　 39例 4 5个膝关节获 1年以上随访 ,采用HSS评分标准 ,膝关节评分从术前 35分提高到术后 89分 ,术后 4 0个膝关节活动度≥ 90°,4 2 / 4 5膝关节术后膝关节力线正常 ,3例残留 5°～ 7°内翻。结论　人工全膝表面关节置换治疗骨性膝关节炎可取得良好效果。术中精确的截骨操作与正确的软组织松解获得的软组织平衡是手术治疗成功的关键。     

初次人工全膝关节表面置换术治疗膝关节骨关节病108例的疗效观察

[目的]探讨初次人工全膝关节表面置换术(total knee arthroplasty,TKA)治疗膝关节病的临床疗效。[方法]对108例130个膝关节行TKA,男50例(60膝),女58例(70膝);年龄47～87岁,平均71.5岁,术前诊断骨性关节炎62例(70膝),类风湿性关节炎37例(51膝),创伤性关节炎4例,滑膜软骨瘤病2例,色素沉着绒毛结节性滑膜炎2例,陈旧关节结核1例,采用后方稳定假体80例(92膝),后交叉韧带保留假体28例(38膝)。[结果]108例患者均获随访,时间24～84个月,平均50.3个月。患者术后在疼痛、功能、活动度方面改善明显,采用HSS评分系统进行评分,由术前平均48.4分提高到89.3分。术后130个膝关节平均活动度为102°,126个膝关节术后力线正常,3例残留6°～8°内翻,1例后遗15°外翻畸形,手术优良率90.5%。[结论]TKA对治疗严重膝关节病效果满意,术中正确的选择切口,注意假体软组织平衡,精确截骨,注重术中髌骨轨迹的纠正是手术成功的关键。     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.     

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.