妊娠产妇在血凝指标筛选试验的临床应用

目的:为探讨常规血凝筛选试验PT,APTT,FIB,TT,在妊娠产妇不同生理条件下的变化,凝血部分的改变会导致在妊娠期特别是晚期或分娩前后发生某些出血、血栓性疾病.方法:对823例妊娠产妇与798例非妊娠产妇(对照组)的凝血功能即凝血酶原时间(PT)活化部分凝血活酶时间(APTT)凝血酶时间(TT)纤维蛋白原(FIB)进行检测.结果:PT,APTT明显缩短于对照组(P＜0.001),FIB高于对照组(P＜0.001)TT值,两组差异无统计学意义(P＞0.05).结论:在产前及分娩过程中,及时检测凝血功能各项指标对预测和治疗产妇异常出血的状态,保护母婴健康有临床意义.     

乌司他丁对肠源性脓毒症大鼠凝血四项和血小板的影响

目的观察乌司他丁（Ulinastatin，UTI）对严重脓毒症大鼠凝血四项和血小板的影响。方法将Wistar大鼠随机分为4组：假手术组（SC组，n=36）、脓毒症组（SEP组，n=30）、乌司他丁3h给药组（UTI3h组，n=30）和12h给药组（UTI12h组，n=18）。利用经典盲肠结扎穿孔法建立脓毒症模型，分别在制模后0、6h、12h、24h、48h及72h心脏取血测定血小板（PLT）和凝血四项[凝血酶原时间（PT）、凝血酶时间（TT）、活化部分凝血活酶时问（APTT）、纤维蛋白原（FIB）]的情况。结果与SC组相比，SEP组大鼠的PT、TT、APTT在造模后逐渐升高，PLT降低，差异有统计学意义（P〈0．05）。与SEP组相比，乌司他丁治疗组大鼠的PT、TT、APTT升高程度及PLT降低的程度都有减轻，差异有统计学意义（P〈0．05），且乌司他丁3h给药组效果好于12h给药组。结论乌司他丁能有效改善严重脓毒症大鼠的凝血紊乱情况，在一定程度上阻断了凝血一炎症间的相互促发的恶性循环，减轻由于凝血系统异常导致的组织器官的损害，保护了器官功能。     

白眉蛇毒血凝酶局部使用对减少胃癌根治术后渗出的疗效观察

观察在胃癌根治术的手术创面局部使用白眉蛇毒血凝酶减少术后渗出的疗效。胃癌根治术治疗患者68例随机分为药物组和对照组各34例。药物组在常规基础治疗的基础上,创面均匀喷洒白眉蛇毒血凝酶4 kU,对照组只喷洒生理盐水。术后观察引流液的量、引流液中VEGF(血管内皮生长因子)、FIB(纤维蛋白原)、t-PA(组织性纤溶酶原激激活物)含量,以及血浆凝血酶原时间(PT)、凝血酶时间(TT)、部分活化凝血活酶时间(APTT)、FIB指标。结果显示,药物组术后5d内每天的引流量都显著低于对照组;术后3h渗出液内FIB含量和t-PA含量显著低于对照组,VEGF含量显著高于对照组,但凝血常规指标无明显变化。结果表明,局部使用注射用白眉蛇毒血凝酶可以显著减少胃癌根治术后创面渗出量,且对凝血常规无影响。     

不同孕期孕妇凝血指标的变化

唐山市人民医院检验科邮编063000摘要:目的:通过检测不同孕期妇女的血浆中的凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)和纤维蛋白原(FIB).探讨不同孕期孕妇凝血功能变化及临床意义.方法:采用美国贝克曼ACL-9000全自动血疑仪,对128例不同孕期组及对照组进行PT、APTT、TT、m指标检测和分析比较.结果:早孕组与对照组比较没有明显差异.中孕组、晚孕组、妊高征组与对照组比较,PT、APTT和TT明显缩短(P＜0.01),m明显增高(P＜0.01).晚孕组和中孕组比较,APTT明显缩短(P＜0.01),Fib明显增高(P＜0.01),PT和TT变化不明显.妊高征组与晚孕组比较,PT、APTT、TT及FIB差异均有显著性(P＜0.01).结论:检测不同孕期孕妇血浆凝血功能指标是否有出血倾向和血栓形成,对预后的发展方向及动态观察有一定临床价值.     

凝血与纤溶系统水平在产妇DIC中的效果比较

目的探讨凝血与纤溶指标在产妇弥漫性血管内凝血（DIC）诊断中的临床意义。方法分别比较DIC产妇（DIC组62例）和健康产妇（健康组55例）的凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）、凝血酶时间（TT）、血浆纤维蛋白原（Fib）及D-二聚体（D-Dimmer）水平。结果与妊娠组相比,DIC组产妇的PT、APTT、TT明显延长（P〈0.05）,FIB明显降低（P〈0.05）,D-D明显升高（P〈0.05）。结论对凝血与纤溶系统水平检测是诊断DIC的必备条件,能够早期提示DIC并及早进行治疗,终止和切断DIC发展。     

227例颅脑创伤患者凝血功能的动态变化及其临床意义

目的：观察和研究各类颅脑创伤患者凝血功能异常的发生率及其临床意义。方法对本院2013年收治的227例单纯性颅脑创伤患者按损伤的性质和类型进行分组并分别检测凝血酶原时间（PT）、部分凝血活酶时间（APTT）、凝血酶时间（TT）和纤维蛋白原（FIB）等凝血功能指标的动态变化。结果227例患者中,颅脑外伤后24小时内凝血功能指标PT、APTT、TT和FIB检测值异常的发生率分别为11%、71.4%、34.4%和21.2%;颅脑外伤后72小时PT、APTT、TT和FIB检测值异常的发生率明显降至2.6%、33.9%、5.7%和17.6%。在各类颅脑创伤中,急性硬膜下血肿患者24小时、48小时、72小时和7天时间段凝血功能指标PT、APTT、TT和FIB检测值异常的发生率均明显高于其他颅脑外伤患者,差异有统计学意义（P＜0.05）。结论颅脑创伤患者伤后24小时内即可出现凝血功能异常,72小时后凝血功能异常的发生率明显降低;颅脑创伤患者凝血功能异常的发生率和持续时间可能与颅脑创伤的性质和类型有关。     

蛇毒血凝酶在腹部手术中止血作用以及对凝血功能的影响

目的：评价蛇毒凝血酶在腹部手术中的止血作用和对凝血功能的影响。方法：采用前瞻,随机、双盲,对照和多中心的方法,将180例腹部手术患者分为血凝酶组（60例）,立止血组（60例）和甘露醇组（60例）,3例患者具有可比性,术前2次分别注射相应药物,对手术切口出血的止血时间,出血时,单位面积同血量以及机体凝血功能（BT,CT,PT,APTT和PLT）等方面进行观察。结果：3组患者给予不同的药物后,血浆酶组的平均止血时间为121．6s,切口出血量为9．6g,单位面积出血量0．2g,与立止血组结果相似（P＞0．05）,而与甘露醇组结果（分别为159．2s,12.5s,0.3g)相比,2组差异有显著性（P＜0．05）,另外,血凝酶和立止血组均能缩短术后30min和术后1d的出,凝血时间,与甘露醇组相比差异有显著性（P＜0．05）,结论：蛇毒血浆酶对腹部切口毛细血管出血有较好的止血作用。     

无肝素连续性静脉-静脉血液滤过在高危出血患者中的应用

目的探讨对高危出血倾向患者行无肝素连续性静脉-静脉血液滤过（CVVH）治疗的可能性。方法37例患者共行CVVH治疗75例次,分为观察组和对照组。观察组43例次,有高危出血倾向,采用无肝素抗凝;对照组32例次,采用低分子量肝素钙抗凝。回顾性分析2组相关临床指标。结果2组治疗后血肌酐（SCr）、尿素氮（BUN）均降低,差异有统计学意义（P〈0．05）,2组SCr、BUN下降率均无统计学差异（P〉O．05）;观察组治疗前、后凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）差异无统计学意义（P〉0．05）,对照组治疗后PT、APTT较治疗前延长,差异有统计学意义（P〈0．05）;观察组有凝血功能障碍的患者管路和滤器使用寿命与对照组无统计学差异（P〉0．05）,观察组无凝血功能障碍的患者管路和滤器使用寿命短于对照组,差异有统计学意义（P〈0．01）。结论无肝素抗凝技术用于高危出血倾向患者的CVVH治疗疗效肯定,并无增加出血的风险。     

慢性肝病患者肝叶切除术凝血-纤溶活性检测的意义

目的探讨慢性肝病患者行肝叶切除术围手术期凝血-纤溶活性的变化及其意义。方法将2003年1月至2004年2月重庆医科大学附属第二医院肝胆外科收治的35例伴乙肝肝硬变的手术患者根据疾病和手术的不同分为肝叶切除术组（n=18）和非肝叶切除术组（n=17），并分别于术前、术毕和术后24h采集外周静脉血，测定其凝血酶原时间（PT）、活化部分凝血活酶时间（APTT）、凝血酶时间（TT）、纤维蛋白原（Fbg）和D-二聚体（D-D）含量。结果非肝叶切除组患者的PT、APTT和TT在手术前后不同时相间比较差异无统计学意义（P〉0．05）；肝叶切除组PT水平术前明显高于术毕和术后，并明显高于非肝叶切除组（P〈0．01），APTT术后则明显高于术前和术毕，也高于非肝叶切除组（P〈0．01），而TT在组内不同时相间及与非肝叶切除组相应时间比较差异无统计学意义（P〉0．05）。2组患者Fbg和D-D水平术后均较术前和术毕明显升高（P〈0．05），但2组间比较差异无统计学意义（P〉0．05）。结论慢性肝病患者实施肝叶切除术时，血液处于低凝和继发性纤溶亢进状态，提示有潜在出血的危险，应加强围手术期处理。     

凝血试验在妊娠晚期中的应用

目的:探讨妊娠晚期孕妇凝血系统的变化及临床意义.方法:用法国STAGO Compact CT全自动凝血仪,测定146例妊娠晚期产前孕妇的血装凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)及纤维蛋白原含量(FIB)并与正常非孕妇女对照比较.结果:PT、APTT、TT妊娠晚期组低于正常非孕妇女对照组,差异有显著性意义(P＜0.01).FIB妊娠晚期组高于正常非孕妇女对照组,差异有显著性意义(P＜0.01).结论:妊娠晚期孕妇血液凝血系统处于高凝状态,进行凝血功能测定有一定的临床意义.     

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.