泌尿外科经腹腹腔镜腹壁穿刺血管损伤的临床分析

目的探讨泌尿外科经腹腹腔镜腹壁穿刺过程发生血管损伤的原因、处理及预防措施。 方法回顾分析我院泌尿外科2012年9月至2017年9月间1 025例经腹腹腔镜手术腹壁穿刺过程出现的6例血管损伤患者的临床资料，分析其原因，总结处理及预防措施。 结果共发生血管损伤6例，其中腹主动脉损伤1例，右髂总动脉损伤1例，腹壁下血管损伤4例，肠系膜动脉损伤1例，其发生率为0.585%（6/1 025）。4例腹腔镜下止血成功，2例中转开放手术止血。 结论腹腔镜腹壁穿刺导致血管损伤由多种原因引起，腹腔粘连、过度消瘦或肥胖是血管损伤发生的危险因素，需术前个体化评估；对腹部血管解剖的深入理解和术中规范操作是减少其发生的关键；掌握血管损伤的临床表现和处理方法，才能降低对患者的创伤及后遗症。     

妇科腹腔镜手术腹壁下动脉损伤致失血性休克2例报告

腹腔镜手术并发症包括腹腔镜手术过程中盆腹腔脏器的直接损伤以及手术操作间接引起的并发症如切口疝等,血管损伤是腹腔镜手术较严重的并发症。本文就我院发生的妇科腹腔镜手术腹壁下动脉损伤致失血性休克2例进行回顾性分析,旨在探讨妇科腹腔镜手术腹壁下动脉损伤的预防和处理。1临床资料例1,26岁,因“发现卵巢囊肿4个月”于2004年9月13日入院。入院诊断:左卵巢浆液性囊腺瘤;先天性心脏病,动脉导管未闭,肺动脉高压,心功能Ⅱ级。入院后在全麻下行腹腔镜左卵巢囊肿剔除术。全麻,仰卧位,取脐孔中央小切口10mm进镜,探查,见左侧卵巢冠囊肿。于左右下腹相当于麦氏点连线位置分别以10、5mm trocar穿刺进腹,钝性剥离囊肿。查创面无活动性出血,生理盐水冲洗,拔镜放气。术后1h患者血压87/67mm Hg,脉搏165次/min;术后2h,血压继续降至70/50mm Hg,贫血貌,下腹叩诊有移动性浊音,各穿刺孔敷料清洁干燥。考虑“腹壁下动脉损伤,失血性休克”,急诊行腹腔镜探查术,见左侧穿刺孔处活动性出血,于搏动性出血部位电凝止血,共出血约2000ml。术后1周复查血红蛋白131g/L,拆除腹壁缝线,痊愈出院。术后病理:符合左卵巢冠囊肿...     

术后腹膜壁层粘连对腹腔镜穿刺安全性的影响

目的　探讨腹部手术后腹膜壁层粘连对腹腔镜穿刺安全性的影响。方法　回顾性分析 13年 810例腹腔镜手术中 12 6例有腹部手术史患者既往腹部手术情况、腹腔镜穿刺方法。结果　腹腔镜下发现 12 6例发生盆、腹腔粘连 3 2例 ,发生率为 2 5 .4% ( 3 2 /12 6)。该 3 2例中附件手术(宫外孕或卵巢囊肿手术 ) 16例 ( 5 0 .0 % ) ,子宫手术 (剖宫产或肌瘤挖出术 ) 10例 ( 3 1.3 % ) ,阑尾切除术 4例 ( 12 .5 % ) ,腹腔镜手术 2例 ( 6.2 % ) ,胆囊切除术后无腹腔粘连。 3 2例术后粘连根据粘连部位划分 ,腹膜壁层粘连 18例 ( 5 6.3 % ) ,原手术部位粘连 14例 ( 4 3 .7% )。无穿刺并发症发生。结论　腹部手术后部分病例腹膜壁层合并大网膜及肠管粘连 ,增加了腹腔镜穿刺的危险 ,但腹部手术史不应成为腹腔镜手术的禁忌证。详细了解既往手术史 ,正确选择第一穿刺部位 ,注意操作 ,是腹腔镜手术穿刺成功的关键     

腹腔镜手术穿刺建立气腹损伤脏器的预防

我院 1995～ 2 0 0 2年 7年中共进行了腹腔镜手术 15 0 0例 ,发生穿刺建立气腹时损伤腹腔脏器 5例 ,报告如下。临床资料我院进行的腹腔镜手术 15 0 0例 ,均是采取 Veress针穿刺建立气腹 ,绝大部分病例是在全麻下进行。总共发生 5例于穿刺建立气腹时损伤腹腔脏器 ,4例损伤大网膜或肠系膜血管的病例 ,1例因出血而中转开腹予以处理 ,另 3例均于腹腔镜中钳夹出血点予以处理 ;1例损伤肠壁 ,被迫中转开腹处理。腹腔镜手术穿刺建立气腹损伤脏器的比例为 0 .33%。另外 5例中有 3例是在用 Vesress针穿刺建立气腹时 ,病人的麻醉深度不够 ,腹肌突然收…     

妇科手术中泌尿系损伤9例临床分析

目的探讨妇科手术中泌尿系损伤的易发因素、临床特点及预防方法。方法对2001年1月1日至2010年12月31日10年间在中山大学附属三院妇科手术中发生泌尿系损伤的9例病例的损伤高危因素、损伤情况、损伤后诊治及预后进行回顾性分析。结果 10年间妇科手术8672例,发生泌尿系损伤9例,发生率为0.10%,其中输尿管损伤6例,发生率0.07%,膀胱损伤3例,发生率0.03%。主要疾病为子宫腺肌症、子宫内膜异位症4例（44.4%）,子宫肌瘤2例（22.2%）,宫颈肌瘤1例（11.1%）,晚期卵巢癌1例（11.1%）,宫颈癌1例（11.1%）。9例中有盆腔粘连7例（77.8%）,子宫增大（6～13周）7例（77.8%）,盆腹腔手术史4例（44.4%）,2例（22.2%）为新开展宫、腹腔镜手术时发生。发现损伤的时间,术中6例（66.7%）,术后3例（33.3%）,术后发现者均为输尿管损伤,症状出现于术后3～14天,包括腹胀、腰疼、低热、尿量减少、阴道流水等。结论盆腹腔的严重粘连、子宫增大、盆腹腔手术史是妇科手术中泌尿系损伤的易发因素,输尿管损伤在术中易漏诊,应重视泌尿系损伤的易发因素,术前术中积极防治以减少损伤。     

腹腔镜取腹腔内异物2例报告

例1,女,50岁。自行从脐旁插入一金属丝10d,伴右下腹疼痛人院。查体：脐右旁有一划痕愈合,右下腹压痛,无反跳痛,未及腹下包块,无腹肌紧张,腹部X线片示：右髂窝金属丝异物。完善检查后行腹腔镜探查术,于脐轮穿刺置入腹腔镜,脐平面两旁距脐6cm穿刺置入操作器械,镜下见右髂窝网膜与前腹壁粘连。分离粘连,显露一金属丝物,取出,检查腹腔内清洁,     

肠粘连患者选择实施腹腔镜粘连松解术的体会

目的：实施气腹造影CT检查诊断肠粘连，筛选局限性腹壁粘连患者施行腹腔镜肠粘连松解术，以获取最佳微创效益。方法：为8例术后疑有腹壁切口肠粘连患者采用腹腔内注气，气腹造影螺旋CT平扫，分析判断肠粘连的病理类型，5例选择性实施腹腔镜肠粘连松解术。结果：气腹造影CT扫描7例均清晰显示肠管、网膜与腹壁切口局限性粘连，其余区域未见粘连，1例为腹腔弥漫性广泛粘连。施5例腹腔镜手术均顺利，腹腔镜手术所见与术前判断完全吻合，仅1例发生1处肠管损伤。结论：CT气腹造影能清晰显示出术后腹壁肠粘连的粘连类型、分布和范围等形态特征，可以选择实施腹腔镜肠粘连松解术的适宜病例，获得理想的微创效果。     

腹腔镜手术穿刺相关出血的原因分析与对策

目的探讨腹腔镜手术中穿刺相关出血的常见原因及相应的对策。方法对2000年5月至2010年10月期间我院腹腔镜手术中发生与穿刺相关出血的16例患者的资料进行回顾性分析。结果 16例患者中腹壁穿刺孔腹膜层出血7例,肌层出血5例,误伤大网膜血管3例,误伤后腹膜血管1例,均在术中及时发现。误伤大网膜血管病例予镜下止血,误伤后腹膜血管病例及时中转开腹手术,腹膜层及肌层出血病例分别给予电灼或缝扎止血。患者均康复出院。结论直视进腹、规范操作和抽吸滴水试验是避免腹腔镜手术穿刺时血管误伤及出血遗漏的有效方法。     

妇科腹腔镜肠道损伤的防范与对策

虽然随着腹腔镜手术技术的提高,腹腔镜手术总的并发症呈下降趋势,但随着腹腔镜手术的广泛开展,手术适应证不断调整、拓宽,手术难度不断增加,并发症特别是严重并发症的发生并不一定减少。肠道损伤是妇科腹腔镜手术罕见(0.1%~0.54%)但严重的并发症之一[1,2]。由于很难在术中及时发现,具有较高的病死率,可造成极为严重的后果,因此应时刻警惕并发症的发生。1肠道损伤的原因既往盆腹部手术史、盆腹腔粘连、胃肠胀气等均为高危因素。①严重粘连:既往盆腹腔手术史,严重盆腹腔粘连,大网膜或肠管粘连,盆腹腔脏器正常位置改变,由于粘连分离中解剖关系错乱,组织层次显示不清,从而增加了进镜和手术器官暴露的困难,致使手术操作中误伤邻近器官。一是增加了气腹针及第一套管针穿刺所致的肠道损伤(发生率为0.07%)[3,4];二是在分离粘连中损伤肠道。重度子宫内膜异位症,由于病变广泛使盆腔严重粘连,在分离子宫与肠管致密粘连的过程中,创面弥漫性出血,子宫与肠管之间解剖层次显示不清,在锐性分离粘连时特别容易损伤直肠前壁。②胃肠胀气,手术空间缩小,操作局部解剖不清晰,手术操作频繁受到干扰。③“清晰而顺利”的手术,如同腹腔镜胆囊切除手术。乃术者麻痹大意,...     

腹腔镜结直肠手术并发症防治

腹腔镜手术与传统手术一样具有发生并发症的风险。有研究表明,术者的腹腔镜手术经验、手术方式及切除范围与并发症发生率密切相关。腹腔镜术中易损伤的器官涉及盆腹腔脏器、腹膜后大血管及神经(包括膀胱、输尿管、胃肠道、肠系膜、大网膜、腹壁血管、主动脉、髂动脉、闭孔神经等)。腹腔镜手术相关并发症主要由两大类原因引起:一方面是机械损伤,可由气腹针及trocar穿刺、各种手术器械如腹腔镜专用剪刀、分离钳、金属夹、结扎环等误伤所致;另一方面是热能量损伤,主要是能量平台如超声刀、电刀、巴克钳、电钩、电剪等电外科产品使用不当引起组织     

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.