全膝关节置换术中髌骨翻转对术后早期膝关节功能的影响

目的评价全膝关节置换术（TKA）中髌骨翻转对术后早期膝关节功能的影响。方法纳入2008年4月至2013年9月32例双侧同期TKA患者,随机分为髌骨翻转组（A组）与髌骨侧方移位组（B组）。比较分析双膝手术时间、术后并发症、实现主动直腿抬高时间和膝关节90°屈曲时间及术后7 d、3个月、6个月、1年膝关节主动活动度、膝关节被动活动度、疼痛视觉模拟评分（VAS）。结果 A 组与B组实现主动直腿抬高的时间分别为（2．6±0．8）d和（2．1±0．6）d（P＝0．043）。除术后6个月两组膝关节被动活动度无统计学差异外,其余各随访时间点A组膝关节主动活动度、被动活动度均较B组差。两组手术时间、术后并发症、实现膝关节90°屈曲时间及VAS评分均无统计学差异。结论 TKA 中髌骨翻转不利于术后早期膝关节功能康复,可延缓患者实现直腿抬高时间,减少术后膝关节活动度。     

髌骨合理设计在全膝关节置换中的临床效果

目的探讨髌骨合理设计后重塑在全膝关节置换(TKA)中的临床效果。方法根据股骨假体滑动轨迹及所需置换髌骨的形态,对56例TKA患者(72膝)术中进行髌骨合理设计并重塑,观察患者术后的关节活动度及疼痛情况,用KSS膝关节评分系统评定治疗效果。结果 56例均获得随访,时间6~18个月。仅1例患者膝关节活动度70°,活动较差,但疼痛明显减轻;其余患者屈曲活动度在0°~110°。KSS评分:优69膝,良2膝,中1膝,优良率达到98.6%。结论术中根据股骨假体滑动轨迹对髌骨合理设计并重塑,可以使未进行髌骨置换的TKA患者取得满意的治疗效果。     

人工全膝关节表面置换治疗骨关节疾病52例

目的探讨人工全膝关节表面置换(TKA)治疗骨关节病的疗效。方法对52例56个膝关节行TKA。结果52例均获随访,时间10~62个月,平均48.4个月。患者术后在疼痛、功能方面改善明显;膝关节评分应用HSS评分系统,由术前平均46.2分提高到86.3分。术后52个膝关节平均活动度为108,°53个膝关节术后膝关节力线正常,3膝残留6°~8°内翻。手术优良率90.4%。结论TKA对治疗严重膝关节炎效果满意,术中精确的截骨及正确的软组织松解以获得软组织平衡和注重术中髌骨轨迹的纠正是手术成功的关键。     

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。     

基于Wiberg分型探讨髌骨形态对髌股关节病变病人全膝关节置换术疗效的影响

目的 基于髌骨Wiberg分型探讨不同髌骨形态对于合并髌股关节病变的膝关节骨关节炎病人全膝关节置换术（total knee arthroplasty,TKA）的疗效影响。方法 将2018年1月至2022年1月接受初次TKA并符合标准的184例病人作为研究对象,根据病人术前髌骨形态Wiberg分型分为W1（Ⅰ型52例）、W2（Ⅱ型93例）、W3（Ⅲ型39例）三组,随访收集并比较病人手术前后的膝前方疼痛发生率、疼痛视觉模拟量表（VAS）评分、牛津大学膝关节评分（Oxford Knee Score,OKS）、Feller评分以及影像学资料。结果 三组病人末次随访时的各项观察指标均较术前明显改善（P<0.05）,其中术后12个月随访时,W3组病人术后膝前痛程度和发生率显著高于W1、W2两组;同时W1、W2组的OKS评分中第12题的得分明显优于W3组,W1、W2组的Feller评分明显高于W3组,差异有统计学意义（P<0.05）。结论 Wiberg分型为Ⅰ、Ⅱ型髌骨的病人TKA术后的膝前痛程度、发生率以及髌股关节功能的改善情况均优于Ⅲ型病人,而部分磨损过于严重的Ⅲ型病人是否适合TKA...     

髌骨修整在人工全膝关节成形术中的应用

背景：全膝关节成形术（TKA）是治疗严重膝关节疾病的有效手段,无论从缓解症状和术后膝关节功能等方面均获得了巨大的成功,然而对于TKA中髌骨的处理方式至今仍存在着广泛的争议。 目的：探讨髌骨修整在人工全膝关节成形术中应用的效果及可靠性。 方法：对2006年1月至2012年1月人工全膝关节成形术中行髌骨修整的40例（42膝）患者进行回顾性分析。术后随访12-36个月（平均22个月）,并对其进行疗效评价,包括膝关节评分（HSS评分系统）、髌骨评分（Feller评分标准）、膝前痛评分、膝关节活动度（ROM）、患者满意度、髌骨相关并发症。 结果：HSS评分由术前的（39.7±9.0）分增至末次随访时的（92.2±7.5）分,髌骨评分由（13.8±6.9）分提高为（26.6±2.8）分,膝前痛分数由（3.5±2.9）分增加为（11.4±3.5）分,ROM由79°±23°改善为120°±14°,术后患者满意度92%,髌骨相关并发症7.1%。HSS评分、髌骨评分、膝前痛评分及ROM术前及术后比较差异有统计学意义。 结论：全膝关节成形术中髌骨修整后髌骨运动轨迹良好,明显改善膝关节功能和明显减轻疼痛。髌骨修整是一种安全可靠有效的髌骨处理方法,临床效果满意。     

全膝关节置换术中髌骨翻转与侧方移位对术后膝关节功能影响的对比分析

目的 分析比较全膝关节置换术（total knee arthroplasty,TKA）中髌骨翻转和髌骨侧方移位对术后膝关节功能的影响。方法 回顾性分析2018年1月至2019年12月我科收治的98例因膝关节骨性关节炎行TKA手术治疗病人的临床资料,按术中髌骨处理方式分为翻转组（45例）和侧方移位组（53例）。比较两组病人的手术时间、主动直腿抬高时间、Insall-Salvati指数、膝关节活动度、美国膝关节协会评分（Knee Society score,KSS）、疼痛视觉模拟量表（visual analogue scale,VAS）评分、并发症发生情况等。结果 两组的手术时间、术中出血量比较,差异均无统计学意义（P均＞0.05）。翻转组的术后直腿抬高时间较侧方移位组明显延长,术后6个月Insall-Salvati指数较侧方移位组明显降低,术后1、2、3、6个月的膝关节活动度、KSS评分均明显低于侧方移位组,VAS评分明显高于侧方移位组,差异均有统计学意义（P均＜0.05）。翻转组术后出现3例膝前痛,2例伤口延迟愈合,2例髌骨低位,侧方移位组未见明显并发症发生。结论 TKA术中髌骨侧方移位可以减少机体髌韧带及股四头肌损伤,获得满意临床疗效,但有待大样本随机对照研究进一步证实。     

全膝置换术中髌骨关节面切除成形

[目的]评价全膝置换术(TKA)中髌骨关节面切除成型的临床效果。[方法] 2017～2019年本院拟行初次TKA的105例骨性关节炎患者纳入本前瞻性研究,随机分为两组。TKA术中,54例患者采用摆锯切除部分髌骨骨软骨,对关节面成形;51例患者仅常规切除周围骨赘及去神经化处理。比较两组围手术期、随访与影像资料。[结果]两组患者术中均无神经、血管损伤等并发症,术中均未输血。两组患者手术时间、术中失血量及术后引流量差异均无统计学意义(P0.05)。末次随访时,髌骨成形组的Feller评分和KOOS评分显著优于常规组(P0.05),但两组间HSS评分的差异无统计学意义(P0.05)。末次随访时,膝前痛发生率髌骨软骨成形组为7.41%(4/54),而常规组为23.53%(12/51),差异有统计学意义(P0.05)。影像方面,末次随访时髌骨成形组的髌股适合角显著优于常规组(P0.05)。[结论] TKA术中髌骨关节面切除成形在改善髌股轨迹、缓解膝前疼痛方面优于常规TKA。     

髌骨钻孔减压改善全膝关节置换术后膝前疼痛

目的探讨通过髌骨钻孔减压术改善全膝关节置换术(TKA)后膝前痛的临床疗效。方法将符合标准的113例行TKA的骨关节炎患者按数字法随机分为两组:54例为减压组,TKA术中联合髌骨钻孔减压术;59例为非减压组,仅施行TKA不联合髌骨钻孔减压术。术后观察两组患者切口愈合情况、相关并发症、KSS评分及膝前痛发生率。结果两组患者切口均一期愈合,无严重并发症发生,113例均获满12个月的完整随访。KSS评分:减压组术后明显高于非减压组;术后膝前痛的发生率明显低于非减压组,差异均有统计学意义(P0.05)。结论 TKA术中联合髌骨减压术可以在一定程度上改善膝关节KSS评分及降低术后膝前疼痛的发生率。     

洛索洛芬在全膝关节置换的围手术期镇痛与术后镇痛中的研究

目的分析洛索洛芬钠片剂对于全膝关节置换（TKA）术后短期临床效果的影响。方法 2009年1月至2009年12月因膝骨关节炎行单侧全膝关节置换手术患者197例,其中围手术期使用镇痛药物为洛索洛芬和（或）阿片类药物的患者84例。仅使用阿片类药物镇痛的患者为对照组,共27例（男9例,女18例）;仅术后使用洛索洛芬镇痛的患者为POST组,共31例（男9例,女22例）;术前和术后均使用洛索洛芬的患者为PERI组,共26例（男7例,女19例）。结果三组患者在平均年龄、体重指数、术前患病时间、术前疼痛评分、术前膝关节活动度、术前HSS评分、手术时间、术中止血带时间、术后引流量、术后2周疼痛评分、术后2周活动度、术后2周HSS评分及术后2周行走距离等指标方面无显著差异。但POST组和PERI组阿片类药物使用时长均短于对照组,阿片类药物末次使用时间也早于对照组（P〈0.05）。与POST组相比,PERI组洛索洛芬用药总量略少,但无统计学显著意义。结论洛索洛芬联合阿片类药物可有效地控制TKA术后疼痛,达到满意的临床效果。联合用药可减少阿片类药物的用量、缩短阿片类药物的使用时间。洛索洛芬围术期镇痛与术后镇痛相比具有基本相同的临床镇痛效果,但前者的用药量略少。     

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.     

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.     

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.