解剖型跟骨钛板治疗SandersⅡ～Ⅳ型跟骨骨折

目的 探讨应用解剖型跟骨钛板治疗SandersⅡ～Ⅳ型跟骨骨折的临床疗效.方法 自2003年7月至2008年7月采用解剖型钢板内固定治疗34例41足SandersⅡ～Ⅳ型跟骨骨折患者,男21例(26足),女13例(15足),年龄21～61岁,平均37.5岁;单足27例,双足7例.采用Maryland足部评分系统(MFS)评分标准对术后效果进行评估.结果 所有患者术后获24～60个月(平均36.5个月)随访,骨折均获骨性愈合,骨折愈合时间为4.7～11.2个月,平均6.3个月,无骨不连及畸形愈合.按MFS评分标准评定疗效:优25足,良11足,一般4足,差1足,优良率为87.8%.结论 解剖型跟骨钛板治疗SandersⅡ-Ⅳ型跟骨骨折可获得满意的临床效果.     

跟骨异形接骨板治疗SandersⅢ、Ⅳ型跟骨骨折的疗效分析

目的探讨跟骨异形接骨板治疗SandersⅢ、Ⅳ型跟骨骨折的疗效。方法自2005年7月至2010年7月本院共收治跟骨骨折97例,其中有36为SandersⅢ、Ⅳ型跟骨骨折患者,手术治疗为32例36足,男29例32足,女3例4足;年龄18-51岁,平均29岁。应用跟骨异形接骨板及自体髂骨或同种异体骨植骨进行有限坚强内固定。结果所有患者术后均获12～30个月（平均24个月）随访,采用Maryland足部评分标准评价手术效果,优21足,良9足,中4足,差2足,优良率为83.3%。结论跟骨异形接骨板治疗SandersⅢ、Ⅳ型跟骨骨折,能够获得较满意的解剖复位,且固定可靠,为功能恢复提供良好条件,能早期功能锻炼,并可减少并发症的发生,临床疗效满意。     

跟骨爆裂骨折手术植骨固定近期疗效临床

目的探讨涉及距下关节的跟骨爆裂骨折手术植骨固定的适应证、方法、植骨材料选择以及对手术效果的影响。方法按照Sander分型标准,筛选符合型和型涉及距下关节的跟骨爆裂骨折患者。自2006年1月至2009年12月我科共计手术复位植骨内固定治疗跟骨骨折18例20足,均使用国产跟骨钛钢板固定,自体骨植骨15足,异体骨植骨5足。结果随访6个月,15足采用自体骨植骨者有1足皮肤伤口延期愈合,5足使用异体骨植骨者均有皮肤切口延期愈合,其中1足切口感染,1足出现骨髓炎。按照Maryland foot Score指标评价,以每一足为分析基数,优13足,良4足,可3足（均系型骨折）,优良率85.0%。结论对于跟骨爆裂骨折,手术内固定时均需植骨,植骨以取自体骨为佳。     

锁定板结合骨修复材料植骨治疗SandersⅢ、Ⅳ型跟骨骨折

目的探讨跟骨锁定板结合骨修复材料植骨治疗SandersⅢ、Ⅳ型跟骨骨折的临床疗效。方法手术治疗30例SandersⅢ、Ⅳ型跟骨骨折患者(32足),骨缺损处植入骨修复材料,行跟骨锁定板内固定。结果患者均获得随访,时间11~30个月。Bhler角:术前为-12.7°~35.2°(12.5°±10.7°),末次随访时为20.0°~37.1°(28.6°±5.2°);Gissane角:术前为80.0°~127.7°(103.6°±14.1°),末次随访时为100.5°~130.5°(117.4°±8.7°);跟骨宽度:术前为36.8~48.6(40.5±2.7)mm,末次随访时为32.8~40.1 mm(36.9±2.0)mm;跟骨高度:术前为33.1~47.2(41.8±3.9)mm,末次随访时为41.0~52.3(46.5±3.0)mm;以上各项指标末次随访与术前比较差异均有统计学意义(P0.01)。参照AOFAS踝-后足评分标准评价手术效果:优10足,良18足,可4足,优良率87.5%。结论锁定板结合骨修复材料植骨治疗SandersⅢ、Ⅳ型跟骨骨折能够复位塌陷的跟骨关节面,固定牢靠,疗效满意。     

锁定钢板内固定治疗跟骨骨折

<正>2012年6月~2013年9月,我院行切开复位锁定钢板内固定治疗28例跟骨骨折患者,疗效满意,报道如下。1材料与方法1.1病例资料本组28例(29足),男21例,女7例,年龄18~75岁。双侧跟骨骨折1例。骨折按Sanders骨折分型:Ⅱ型8足,Ⅲ型12足,Ⅳ型9足。其中合并腰椎骨折1例。     

植骨钛板内固定治疗跟骨骨折24例

目的分析切开复位加植骨钛板内固定治疗跟骨骨折的疗效。方法对我院2005年8月至2008年1月期间24例累及关节面跟骨骨折做切开复位钛钢板内固定加自体骨植骨治疗的患者进行随访分析。24例患者中,男17例18足,女7例,年龄20～56岁,平均31．3岁。按Sanders分型,Ⅱ型9例,Ⅲ型12例13足,Ⅳ型3例。全部病例均行切开复位解剖钢板内固定加植骨治疗,并在患者出院后进行随访。结果随访时间6～36个月,平均21．2个月,骨折全部愈合。术后患足功能按Maryland Foot Score评分标准,优18例,良2例3足,中3例,差1例,优良率83．3％。结论通过植骨及钛板内固定可恢复跟骨塌陷骨折距下关节面的完整,重建跟骨高度及Bohler角,提供稳定性,可行早期功能锻炼,是治疗跟骨骨折的较好的方法。     

经内踝截骨空心螺钉内固定治疗距骨体部骨折

[目的]探讨经内踝截骨入路切开复位内固定治疗距骨体部骨折的临床疗效。[方法]自2005年3月~2013年1月,收治距骨体部骨折患者32例,男25例,女7例,年龄21~52岁,平均34岁;坠落伤19例,车祸伤8例,重物砸伤5例;左侧15例,右侧17例;合并踝关节骨折5例,开放骨折脱位1例(CustiloⅡ型)。按照Sneppen’s距骨体骨折分型:Ⅱ型26例,Ⅴ型6例,均为新鲜骨折病例。所有患者均行经内踝截骨入路空心螺钉内固定手术治疗。术后定期复查X线片,并采用美国足踝外科协会(AOFAS)踝与后足评分系统评估功能恢复情况。[结果]全部病例均获得平均20个月(17~36个月)的随访,无伤口感染、神经损伤等并发症发生,术后AOFAS踝与后足评分平均为81分(58~95分),6例继发创伤性关节炎,2例发生距骨缺血性坏死。与传统双切口方式治疗距骨体部骨折相比,术后疼痛、创伤性关节炎发生率差异有统计学意义(P0.01),术后关节活动度、距骨缺血坏死率差异无统计学意义(P0.05)。[结论]经内踝截骨手术入路治疗距骨体部骨折术中显露充分,有利于骨折复位固定,并发症发生率低,治疗效果满意。     

开窗直视下联合复位内固定治疗跟骨骨折

目的探讨跟骨外侧开窗直视下联合复位钢板内固定治疗跟骨骨折的临床疗效。方法对36例(38足)SandersⅡ~Ⅳ型跟骨骨折患者采用跟骨外侧切口,在跟骨外侧皮质开窗后直视下复位塌陷的关节面,尽量恢复Gissane角、Bhler角;对有骨缺损者行自体髂骨及异体骨植骨后钢板内固定。术后X线片上测量Bhler角、Gissane角及跟骨的长度、宽度、高度,与术前进行比较。按照Maryland足功能评分系统对患者术后功能进行评定。结果 31例患者(32足)获得随访,失访5例(6足),随访时间12~24个月。术后1年X线片示骨折处均达到骨性愈合。Bhler角:术前-3.6°±5.8°、术后29.4°±4.0°,差异有统计学意义(P0.05);Gissane角:术前88.9°±6.3°、术后115.9°±5.6°,差异有统计学意义(P0.05)。术后跟骨长度、宽度及结节部高度与术前比较差异均有统计学意义(P0.05)。采用Maryland足功能评分标准评估术后功能:优11足,良13足,可5足,差3足。结论跟骨外侧开窗直视下联合复位内固定治疗跟骨SandersⅡ、Ⅲ型骨折疗效满意,SandersⅣ型骨折疗效尚可。     

解剖钢板内固定并植骨治疗跟骨骨折骨缺损的临床研究

目的探讨解剖钢板内固定、内固定并自体植骨、内固定并同种异体骨植骨3种手术方法治疗跟骨骨折骨缺损的临床疗效。方法对129足跟骨骨折骨缺损按照治疗方法分组。A组:钢板内固定36足;B组:内固定并自体骨48足,C组:内固定并异体骨45足。全部病例按Sanders分型:A组Ⅱ型骨折10足,Ⅲ型17足,Ⅳ型9足;B组Ⅱ型骨折12足,Ⅲ型23足,Ⅳ型13足;C组Ⅱ型骨折9足,Ⅲ型21足,Ⅳ型15足。手术前后对Bohler角、Gissane角、跟骨水平全长、丘部总高、轴长和体宽等多项指标进行比较,按Marryland评分系统评价术后功能。结果术后A组3例切口延迟愈合,1例腓肠皮神经损伤,1例腓骨长短肌腱滑脱。术后功能评价:A组优16足,良15足,可5足,优良率86.11%。B组1例切口延迟愈合,1例腓肠皮神经损伤;优30足,良14足,可4足,优良率91.67%。C组2例切口延迟愈合,1例腓骨长短肌腱滑脱;优28足,良14足,可3足,优良率93.33%。结论自体植骨和异体植骨结合内固定与单纯钢板内固定在治疗严重跟骨骨折远期疗效上差异有统计学意义,自体植骨内固定和异体植骨内固定疗效差异无统计学意义。     

跟骨骨折内固定23例疗效分析

目的探讨跟骨骨折采用AO钛板结合克氏针内固定治疗的临床疗效。方法总结我院2008年2月至2010年5月住院治疗涉及距下关节的跟骨骨折患者23例31足,其中男17例,女6例;单足15例,双足8例。按Sanders分型,型11足,型20足。均采用AO跟骨钛板结合克氏针内固定的方法进行跟骨骨折内固定治疗,参照美国足踝外科Maryland足部评分系统标准进行足部功能评分。结果本组23例患者均获随访,随访时间6个月~2年,平均15个月。术后X线显示骨折全部愈合,关节面及Blher′s角恢复满意。按Maryland足评分系统评价,优18足,良8足,可5足,优良率为83.8%。结论跟骨钛板结合克氏针内固定治疗跟骨骨折具有较好的临床疗效。     

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.     

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.     

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.     

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.