感染性心内膜炎急诊外科治疗

目的　报告一组感染性心内膜炎病人行急诊外科治疗的经验。方法　 36例病人中 ,34例次 (94% )有赘生物 ,19例次 (5 2 % )瓣膜穿孔 ,2 9例次 (81% )严重瓣膜关闭不全 ,均在体外循环下行紧急外科手术 ,切除和清除感染瓣膜、组织、赘生物。用 0 2 %呋喃西林、先锋霉素溶液反复冲洗 ;置入机械瓣 ,矫治心内畸形。结果　 33例恢复出院 ,包括 2例术前因进行性充血性心力衰竭、休克 ,心跳骤停 ,在心肺复苏、呼吸机辅助下行急诊瓣膜置换手术者。 3例术后死亡 ,病死率为 8 3%。 1例死于心力衰竭及多器官功能衰竭伴III度房室传导阻滞 ,2例死于严重低心输出量综合征及急性肾功能衰竭。 36例术后病理证实为感染性心内膜炎。结论　感染性心内膜炎出现进行性充血性心力衰竭和感染不能控制时 ,赘生物需接受紧急外科手术治疗 ;紧急手术不会使感染灶扩散 ;置换瓣膜时可选用人工机械瓣膜     

感染性心内膜炎的外科治疗

目的探讨感染性心内膜炎（IE）的外科手术治疗效果及围术期处理原则。方法回顾性分析2001年3月～2010年10月接受感染性心内膜炎手术治疗患者15例的临床资料。术前经超声心电图检查证实心内赘生物形成者15例。所有患者均经外科手术清除感染病灶及赘生物,并纠治瓣膜病变和心脏畸形,术前术后应用大剂量敏感抗生素。结果术后早期死亡1例（6.7%）,术后随访时间3～48月,随访14例（93.3%）,均无心内膜炎复发,心功能恢复I级12例,Ⅱ级2例。结论外科手术治疗感染性心内膜炎是一种有效的治疗方法。正确掌握手术时机,彻底清除感染病灶,恢复瓣膜功能以及围手术期应用有效抗生素是提高感染性心内膜炎治愈率的生要措施。     

感染性心内膜炎104例的临床分析

摘要：目的探索感染性心内膜炎的临床特点及治疗结果,以提高其临床疗效。方法回顾性分析2008年1月至2009年12月北京阜外心血管病医院104例感染性心内膜炎患者的临床资料,其中男64例、女40例,平均年龄40．8岁,血培养阳性47例（45．2％）。超声心动图检查提示：90例（86．5％）心脏瓣膜或流出道有赘生物,赘生物位于主动脉瓣36例,二尖瓣32例,三尖瓣11例,右心室流出道3例,多个瓣膜6例。据血培养结果行药物或外科手术治疗,术前及术后应用敏感抗生素治疗。结果全组33例行内科药物治疗,病死率为33．3％（11／33）;72例行外科手术清除赘生物及进行心脏基础病变治疗,病死率为4．1％（3／72）。死亡原因1例为低心排血量,1例感染,1例脑梗塞。赘生物培养均为阴性。体外循环时间（117．5±63.3）min,主动脉阻断时间（82．7±44．8）min。总的中位住院时间30．9d,术后住院时间13（6～41）d。术后有3例感染再发,2例因为瓣周漏引起感染再发,1例行瓣膜成形术后感染再发。结论基础心脏病仍是感染性心内膜炎常见病因。早期、有效、规律的抗生素治疗仍是治疗基础,及时的外科治疗可降低病死率。     

三尖瓣感染性心内膜炎的外科治疗

目的分析三尖瓣感染性心内膜炎的外科治疗效果。方法回顾性分析接受心血管外科手术治疗的右心感染性心内膜炎病人51例的临床资料,所有病人在体外循环下行赘生物清除、合并心脏畸形矫治及三尖瓣手术,术后抗生素使用2～4周。结果术后1例病人二次开胸止血,1例病人术后1年出现二尖瓣赘生物,1例病人术后3个月间断发热持续4年再次出现三尖瓣赘生物行二次手术,1例病人术后蛛网膜下腔出血、急性肾损害、败血症转院,50例病人治愈出院,随访6个月～13年,病人心力衰竭症状明显改善,2例复发。结论通过外科手术可有效治疗由先天性心脏病、瓣膜病或做过心脏手术引起的三尖瓣感染性心内膜炎,并得到满意效果。     

静脉注射吸毒者感染性心内膜炎的外科治疗

目的 探讨静脉注射毒品所致感染性心内膜炎的外科治疗经验.方法 17例患者静脉注射毒品史2～10年,均有心脏瓣膜赘生物;其中三尖瓣赘生物并关闭不全16例,二尖瓣赘生物并关闭不全合并室间隔缺损1例,术前血培养阳性8例.三尖瓣置换术8例,三尖瓣成形术8例,二尖瓣置换同期室间隔缺损修补术1例.术后平均随访(44.7 ±19.1)月.结果 全部患者治愈出院,心功能明显改善,随访期间抗凝不当致大咯血1例,三尖瓣重度返流1例.结论 外科手术修复受累瓣膜或置换瓣膜是治疗静脉吸毒性感染性心内膜炎的有效手段.     

感染性心内膜炎的外科治疗

目的评价外科手术治疗感染性心内膜炎的经验和效果。方法回顾性分析15例感染性心内膜炎的外科治疗方法。先天性心脏病5例,风湿性心脏瓣膜病9例,右心室异物1例。术前超声检查赘生物形成14例,血培养阳性4例。全组病例中行心脏缺损矫正修补5例,主动脉瓣置换术5例,二尖瓣置换术4例。结果全组病例均无术中死亡,1例术后因严重低心排综合征早期死亡,14例治愈出院,随访6个月～4a,预后良好,无复发及死亡病例。结论手术治疗感染性心内膜炎是一种有效的治疗措施,它降低了感染性心内膜炎的病死率。正确掌握手术时机,彻底清除感染病灶,恢复瓣膜功能以及围手术期应用有效抗生素是提高感染性心内膜炎治愈率的关键。     

静脉注射毒品致感染性心内膜炎的外科治疗

目的总结静脉注射毒品所致感染性心内膜炎的外科治疗经验。方法15例静脉注射毒品患者,均有心脏瓣膜赘生物,其中三尖瓣赘生物并关闭不全14例,二尖瓣赘生物并关闭不全合并室间隔缺损1例,术前血培养阳性8例。行三尖瓣置换术6例,三尖瓣成形术8例,二尖瓣置换同期行室间隔缺损修补术1例。结果均手术治愈,心功能明显改善,2例有轻度三尖瓣关闭不全。术后均获随访,平均时间(46.8±22.3)月。随访期间抗凝不当致大咯血1例,予维生素K1治疗后痊愈,三尖瓣重度关闭不全1例,予强心利尿等内科处理维持。结论外科手术修复受累瓣膜或置换瓣膜是治疗静脉注射毒品致感染性心内膜炎的有效手段。     

儿童感染性心内膜炎的外科治疗

目的：总结儿童感染性心内膜炎的外科治疗经验，以期掌握好手术时机及指征，提高手术成功率。方法：28例儿童心内膜炎病人，7例因急性心力衰竭、栓塞或严重败血症急诊手术；21例经抗生素治疗体温正常后择期手术。彻底清除赘生物后，同时行主动脉瓣瓣膜置换5例，主动脉根部拓宽、主动脉瓣瓣膜置换2例，室间隔缺损（室缺）修补5例，室缺修补、右室流出道疏通2例，室缺和佛氏窦瘤修补2例，室缺修补、主动脉瓣瓣膜置换2例，动脉导管缝扎3例，动脉导管缝扎、主动脉瓣瓣膜置换1例，二尖瓣瓣膜置换3例，二尖瓣瓣膜置换、左冠前降支取栓并搭桥1例，法洛四联症矫正、Rastelli手术和1例。同期行三尖瓣成形6例、肺动脉瓣成形7例。结果：手术死亡1例（3．6％），死亡原因为术后霉菌性感染不能控制、多器官功能衰竭。术后平均随访2．6年，心内膜炎复发2例，无远期死亡。结论：儿童感染性心内膜炎手术治疗的远期效果满意，其手术时机及指征的掌握对治疗效果至关重要。     

复杂性感染性心内膜炎的外科治疗

目的评价瓣周脓肿、心肌脓肿以及瓣膜严重毁损等复杂性感染性心内膜炎手术治疗的近、远期疗效.方法回顾性分析1988年12月至2002年6月手术治疗的复杂性心内膜炎患者57例临床资料,均为原发性心内膜炎,其中感染侵犯主动脉瓣25例、二尖瓣16例、二尖瓣和主动脉瓣16例.术中发现瓣叶严重毁损32例、主动脉瓣周脓肿19例、主动脉根部环形脓肿导致左心室-主动脉连接破坏4例、二尖瓣后瓣环脓肿11例、心肌脓肿6例、瓣膜赘生物形成55例.脓肿清除后遗留残腔采用间断褥式缝合6例、自体心包片修补19例、牛心包片修补6例、聚四氟乙烯膨体补片修补4例;施行以带瓣管道作升主动脉根部替换和左、右冠状动脉移植术4例,主动脉瓣替换术21例,二尖瓣替换术16例,主动脉瓣及二尖瓣双瓣替换术16例.结果早期死亡6例(11%),死亡主要原因为低心输出量综合征、人造心脏瓣膜性心内膜炎和多脏器功能衰竭.随访4个月至14年,平均(5.93±0.20)年.晚期死亡5例,晚期主要并发症为人造瓣膜性心内膜炎.术后1年心功能恢复NYHA分组Ⅰ～Ⅱ级占96%(44/46);5年再手术免除率为(84±3)%,5年实际生存率为(61±9)%.结论复杂性心内膜炎局部组织破坏较多,应限期手术或急症手术,清创后残腔的处理是影响手术本身能否成功以及术后近、远期效果的关键.     

85例感染性心内膜炎的临床诊断与外科治疗

【摘要】 目的 总结感染性心内膜炎(IE)的临床诊断、外科手术和围手术期处理的经验。方法 回顾性分析2004年9月至2012年12月在我院接受手术治疗的85例IE患者的临床资料。其中男52例,女33例,年龄15~71岁,平均年龄35±16.2岁。85例患者中,12例患者接受了急诊手术治疗;71例患者术前进行了血培养检查,其中阳性18例(阳性率25.4%);超声心动图检查发现赘生物患者73例。所有患者均经外科手术清除感染病灶,纠治瓣膜病变及心脏畸形。结果 全组无手术死亡,均痊愈出院。随防72例,随防时间2~95月,平均53.3±26月,1例因自行停服抗凝药导致机械瓣栓塞死于出院后半年。其余71例术后感染性心内膜炎均未复发。术后心功能恢复至I级61例,心功能恢复至II级24例。结论 早期诊断、适时手术,彻底清除感染病灶,和正确使用抗生素是治疗感染心内膜的重要措施。     

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.