Comparative study between propofol and thiopental for anesthesia induction in surgery of short duration]

To compare anesthetic characteristics of thiopental and propofol in short duration surgical interventions, we have studied 40 patients undergoing gynecologic and proctologic surgery. Patients were randomly assigned to two groups receiving 2.5 mg/kg of propofol or 5 mg/kg of thiopental. In both groups, arterial hypotension of comparable intensity occurred. Heart rate was significantly higher in thiopental anesthesia. Postanesthesia recovery was significantly more rapid with propofol. Some of these results can be influenced by the different immediate premedication (atropine and diazepam in thiopental group) and duration of anesthesia.     

Comparative hemodynamic study of anesthesia induction with propofol (Diprivan), thiopental, methohexital, etomidate and midazolam in patients with coronary disease

In patients undergoing cardiac surgery, the induction of anesthesia is not without risk because of specific cardiovascular effects of the anesthetic and the preoperative state of the patient. The hemodynamic effects of etomidate, midazolam, thiopental, and methohexital are well known: etomidate is an anesthetic that induces only minor cardiovascular changes; its influence on the endocrine system, however, has reduced its clinical indication. Barbiturates such as thiopental and methohexital produce negative inotropic effects in combination with an increase in heart rate and myocardial oxygen consumption; midazolam reduces pre- and afterload in patients with poor left ventricular function. Propofol, a new short-acting induction agent with good anesthetic properties, is said to diminish arterial pressure as well as myocardial oxygen consumption. METHODS: In a randomized study we investigated the hemodynamic effects of intravenous induction with propofol (2 mg/kg body wt.), thiopental (5 mg/kg), methohexital (1 mg/kg), etomidate (0.3 mg/kg), and midazolam (0.15 mg/kg) in 50 patients undergoing coronary artery bypass grafting. All patients were premedicated with flunitrazepam (0.03 mg/kg up to 2 mg) and morphine hydrochloride (0.2 mg/kg up to 15 mg) 100 min before the investigation. After 0.003 mg/kg fentanyl the patients received the induction agent in the above-mentioned dosage within 40 s followed by 0.1 mg/kg pancuronium bromide. Hemodynamic measurements were performed 1, 3, and 5 min after the end of the injection as well as 1 and 5 min after intubation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inotropic and anesthetic potencies of etomidate and thiopental in dogs

The effects of etomidate and thiopental on myocardial contractility were compared in 10 experiments on isolated papillary muscle preparation perfused by a conscious donor dog. Equianesthetic doses of etomidate (1.4 mg/kg) and thiopental (15.5 mg/kg) were determined separately in conscious dogs. Tension developed by the papillary muscle decreased significantly less after etomidate (17 +/- 2%) than after thiopental (33 +/- 3%) (P less than 0.002) when injected intravenously in equianesthetic doses in donor dogs. When added to arterial blood perfusing the papillary muscle, etomidate had 4-5 times more negative inotropic effect than thiopental. At the same time, the anesthetic potency of etomidate was approximately 11 times greater than that of thiopental. We conclude that both etomidate and thiopental produce a dose-dependent direct negative inotropic effect but that in equianesthetic doses, etomidate causes less pronounced depression of myocardial contractility than thiopental.     

依托咪酯和丙泊酚单一制剂在胃镜操作全麻方案的比较研究

目的 比较依托咪酯和丙泊酚单一制剂在全麻胃镜操作中的应用特点.方法 择期行胃镜检查术100例,用随机数字表法随机分为依托咪酯(E)组和丙泊酚(P)组,双盲法给药.E组静注依托咪酯0.3 mg/kg,术中胃镜置入时追加0.1 mg/kg.P组静注丙泊酚2.5 mg/kg,术中胃镜置入时追加1 mg/kg.Ramsay分级...     

Comparative study between thiopental and propofol in short-duration anesthesia

In a randomized study, 80 healthy unpremedicated female patients were included. For short gynaecological procedures (curettage) they were anaesthetized with either propofol 2 mg/kg (n = 40) or thiopentone 5 mg/kg (n = 40) in combination with nitrous oxide/oxygen (1/1). Supplementary doses of propofol (25 mg) or thiopentone (50 mg) were given when necessary during the procedure. Propofol caused a significant fall in arterial blood pressure (greater than thiopentone in diastolic pressure) and a decrease in heart rate (thiopentone did not change heart rate). Discomfort on injection was similar in both groups. Recovery times were shorter in propofol group: Patients opened their eyes at 1.3 minutes, were awake at 2.2 minutes and could seat with no help at 5.2 minutes. In the thiopentone group, there was a greater incidence of nausea. Propofol was associated with euphoria, "clear-headedness" and pleasant dreams more than thiopentone. We conclude that propofol is a good alternative to thiopentone in short operative procedures.     

Induction and recovery characteristics of propofol, thiopental and etomidate

Propofol, thiopental and etomidate, with 20 patients in each group, were compared for anesthesia of short duration in women undergoing termination of pregnancy, with respect to: 1: pain on injection (equally often after propofol and etomidate, but more rarely after thiopental); 2: apnea following induction (no difference); 3: involuntary muscular movements more frequent after etomidate); 4: blood pressure (larger drop after propofol); 5: heart rate (greater increase after thiopental); 6: time to eye opening on command (longer after propofol); 7: Steward score on eye opening (no difference); 8: coin counting after 15, 30 and 60 min (performance better after propofol at 15 and 30 min, producing even shorter times than preoperatively at 60 min); 9: reaction time after 15, 30 and 60 min (performance better after propofol, producing even shorter times than preoperatively at 60 min. It is concluded that the faster recovery gives propofol an advantage over thiopental and etomidate in outpatient anesthesia.     

Comparative study of the efficacy and tolerance of propofol and thiopental in induction and in continuous perfusion with neuroleptanesthesia

We have studied 40 ASA I/II patients aged from 18 to 65 years undergoing otorhinolaryngologic surgery of 40-100 minutes of duration. Patients were randomly assigned to two groups. Anesthesia in group I was induced with thiopental, 4 mg/kg and maintained with N2O at 66% and a variable perfusion of fentanyl. In group II, anesthesia was induced with propofol, 2.5 mg/kg and maintained with a perfusion of 6-12 mg/kg/hour and an initial perfusion of fentanyl, 4 micrograms/kg/hour. Loss of consciousness occurred in 37.49 +/- 9.78 seconds in group I and in 46.25 +/- 12.62 seconds in group II, with no significant differences. Two minutes after induction, propofol group presented a significant decrease in systolic blood pressure of - 12 mm Hg and both groups presented comparable increases in systolic blood pressure and heart rate during intubation. Five minutes later, systolic blood pressure regained normal values. Maintenance in group II was achieved in a proper fashion with a mean propofol consumption of 9.5 +/- 2.6 mg/kg/hour and fentanyl consumption of 4.94 +/- 2.22 micrograms/kg/hour whereas in group II, with N2O at 66%, the amount of fentanyl required was 6.85 +/- 2.95 micrograms/kg/hour, which was significantly higher. Eye opening from the time of interruption of anesthetics was achieved at 6.6 +/- 3.2 minutes in group I and 12.44 +/- 6.34 in group II. Consciousness was regained at 11.25 +/- 3.96 and 16.87 +/- 6.95 minutes, respectively. Pain on injection occurred in 15% with propofol and in 10% with thiopental. No patient presented major complications nor phlebitis after administration of the anesthetic.     

The effects of etomidate, thiopental, and propofol in induction on hypoperfusion-reperfusion phenomenon during laparoscopic cholecystectomy

BACKGROUND: A hypoperfusion-reperfusion human model is observed during and soon after laparoscopic surgery. The aim of the study was to research the preventive effects of etomidate, thiopental, and propofol in induction on hypoperfusion- reperfusion phenomenon during laparoscopic cholecystectomy. METHODS: Thirty-six consecutive ASA I-II patients were randomized into three groups of 12 patients each. Anaesthesia was induced with etomidate in group 1, thiopental in group 2, and propofol in group 3. Venous blood samples were obtained at different time points for measurement of plasma malondialdehyde (MDA) levels. Arterial blood and gastric juice samples were obtained for the calculation of gastric intramucosal pH (pHi). Also changes in aminotransferases, alkaline phosphatase and total bilirubin levels were assessed. RESULTS: There was a significant decrease in pHi at 1 min before desufflation (BD) and 20 min after desufflation (AD) compared with before insufflation (BI) in all groups. Plasma level of MDA was significantly increased in group 1 at 1 min BD and 20 min AD compared with before induction of anaesthesia (baseline). Malondialdehyde levels were decreased significantly in group 3 and increased non-significantly in group 2 at the same time points. Also AST and ALT levels were significantly increased in both groups 1 and 2 at 24 h postoperatively. CONCLUSION: Propofol with antioxidant activity may offer many advantages by scavenging reactive oxygen species and their metabolites in case of anticipated hypoperfusion-reperfusion phenomenon, such as would occur in laparoscopic surgery.     

Comparative study of propofol and sodium thiopental in short-duration anesthesia

We have compared propofol and sodium thiopental in two groups of 20 women undergoing curettage. Patients received premedication with diazepam and were randomly allotted to propofol group (2 mg/kg, intravenously) or sodium thiopental group (5 mg/kg, intravenously). Anesthesia maintenance was carried out with spontaneous ventilation with 0(2)-N2O. When complementary doses were required, 20% of the initial dose was administered. There were no significant differences with respect to base arterial blood pressure and heart rate on induction, 2 minutes after induction and at the end of the operation. The time from the end of the operation to the patient began to respond to the order of open eyes and to the patient was aware enough to establish a coherent talk and to seat without help was similar in both groups. Adverse effects were minor in bith groups and significantly more frequent in propofol group. We conclude that propofol is a particularly interesting new anesthetic agent for short duration anesthesia.     

Gastroesophageal reflux during anesthetic induction with thiopental and succinylcholine

The effects of patient physiology and the prior administration of a nondepolarizing muscle relaxant on the frequency of gastroesophageal reflux during induction with thiopental sodium and succinylcholine were investigated. Forty patients underwent anesthetic induction during continuous esophageal pH monitoring. Twenty patients had preoperative symptoms of gastroesophageal reflux, and 20 asymptomatic patients served as controls. Half the patients in each group received a small dose of nondepolarizing muscle relaxant prior to induction. Five patients (25%) with gastroesophageal reflux and none of the control patients showed significant decreases in esophageal pH during induction. Two of these patients received prior administration of a nondepolarizing drug. In all five patients, reflux occurred during laryngoscopy and intubation, suggesting the possibility that succinylcholine did not play a role in the generation of reflux. Preoperative gastroesophageal reflux symptomatology is associated with an increased frequency of reflux during induction, and the vulnerable period seems to occur after the achievement of neuromuscular blockade during laryngoscopy. Preinduction administration of a non-depolarizing muscle relaxant prior to succinylcholine use had no demonstrable effect on the frequency of reflux during induction, although the numbers studied were too small to be conclusive.     

The effects of thiopental and generic and nongeneric propofol on respiratory resistance during anesthetic induction in patients with reactive airways

STUDY OBJECTIVE: To demonstrate a favorable effect of propofol on respiratory system resistance during anesthetic induction, and to determine if generic propofol causes adverse effects on respiratory resistance. DESIGN: Randomized pilot study. SETTING: Anesthetic induction for elective surgery. PATIENTS: 27 consenting ASA physical status II and III patients with reactive airways (positive smoking history or chronic obstructive pulmonary disease), but not receiving bronchodilator therapy. INTERVENTIONS: Patients were randomized equally to one of three anesthetic induction (and maintenance) drugs: sodium thiopental, 5 mg/kg (25 microg/kg/min), generic or nongeneric propofol, 1.25 mg/kg (50 microg/kg/min). They received preinduction midazolam and fentanyl (2 mg and 150 microg) and intravenous lidocaine (0.5 mg/kg). After anesthetic induction, tracheal intubation was established, and predetermined settings for mechanical ventilation were initiated. MEASUREMENTS: Immediately after intubation, a sensor was placed on the 8-mm endotracheal tube to detect baseline airway pressure and flow. During maintenance, repeat measurements of pressure and flow were obtained at 2.5-minute intervals for 10 minutes. Respiratory system resistance was derived off-line using the isovolumetric technique. MAIN RESULTS: Patients were similar across groups. The respiratory resistance measured after anesthetic induction did not differ among groups. During the maintenance infusion of thiopental or propofol, respiratory resistance increased gradually across all groups. There was no difference in the response of respiratory resistance either at induction or during the 10-minute maintenance between the generic and the nongeneric propofol groups. CONCLUSIONS: In contrast to earlier reports, this pilot study was unable to document a difference in the respiratory resistance in patients induced with thiopental or propofol. In addition, we were unable to demonstrate any different respiratory responses between generic propofol, containing sodium metabisulfite preservative, and nongeneric propofol.     

Midazolam potentiates thiopental sodium anesthetic induction in patients

STUDY OBJECTIVE: To test the hypothesis that midazolam potentiates thiopental sodium-induced unconsciousness. DESIGN: Randomized, double-blind study. SETTING: A university medical center. PATIENTS: Fifty nonpremedicated ASA physical status I and II adult patients scheduled for eye surgery. INTERVENTIONS: Intravenous (IV) injections of thiopental sodium in doses ranging from 1.0 mg/kg to 4 mg/kg with or without the addition of midazolam 0.02 mg/kg. MEASUREMENTS AND MAIN RESULTS: Inability to open eyes on command was used as an end point of anesthesia and the dose-response curves were determined using a probit procedure. A dose of 0.02 mg/kg, which constitutes less than one-tenth of the hypnotic ED50 value for midazolam, potentiated thiopental sodium anesthesia. The thiopental sodium ED50 value was decreased from 2.4 mg/kg to 1.6 mg/kg (p less than 0.001). Midazolam also reduced individual variability in the response to thiopental sodium. As a result, the thiopental sodium dose that reliably induced any nonpremedicated patient decreased from 6 mg/kg (ED99 of 5.57 mg/kg) to 2.5 mg/kg (ED99 of 2.37 mg/kg). CONCLUSIONS: A subhypnotic dose of midazolam potentiates thiopental sodium-induced unconsciousness. This effect suggests the possibility that midazolam enhances barbiturate binding.     

Anaesthetic induction with alfentanil: comparison with thiopental, midazolam, and etomidate

The speed, side effects and cardiovascular changes associated with anaesthetic induction and endotracheal intubation following alfentanil (20 micrograms/kg/min, IV), thiopental (84 micrograms/kg/min, IV), etomidate (5 micrograms/kg/min, IV) and midazolam (20 micrograms/kg/min, IV) prior to halothane-nitrous oxide general anaesthesia were evaluated and compared in 80 patients undergoing elective general surgical operations. Anaesthetic induction was fastest with etomidate and thiopental (approximately one minute) and slowest with midazolam (about two minutes). Systolic arterial blood pressure (SBP) was decreased at the moment of unconsciousness with thiopental but unchanged with the other compounds. Heart rate (HR) was increased at unconsciousness with midazolam and thiopental but unchanged with etomidate and alfentanil. After intubation HR was increased in all groups except those induced with alfentanil. Arrhythmias were infrequent (5 per cent or less in all groups). Rigidity during induction only occurred with alfentanil (55 per cent) and pain on injection only with etomidate (35 per cent) and alfentanil (5 per cent). Postoperative vomiting was infrequent in all groups (15 per cent) except etomidate (55 per cent). No patient remembered any aspect of laryngoscopy or the operation and all rapidly regained consciousness at the end of operation. The results of this study demonstrate that with the exception of rigidity (which is easily overcome with succinylcholine) and a slightly slower onset of action, alfentanil compares favourably as an induction agent with thiopental and is better than midazolam and etomidate. Alfentanil is superior to all three other induction agents with respect to cardiovascular stability during induction and intubation.     

Comparison of the effects of remifentanil or fentanyl on anaesthetic induction characteristics of propofol,thiopental or etomidate

BACKGROUND AND OBJECTIVE: This prospective, randomized, double-blinded study was designed to compare the effects of remifentanil or fentanyl on anaesthetic induction characteristics of propofol, thiopental or etomidate. METHODS: Seventy-two patients were enrolled in six groups of 12 individuals each. In three groups, fentanyl was given as a bolus dose of 1.5 microg kg(-1), whereas the others received a remifentanil infusion at 0.5 microg kg(-1) min(-1). Five minutes later, propofol, thiopental or etomidate were titrated to a state of unresponsiveness. Assessment included the amounts of drug necessary for induction, haemodynamics and the times to apnoea, loss of eyelash reflex, and the release of a water-filled syringe held in the patient's hand. RESULTS: Induction times to loss of the eyelash reflex were significantly shorter in the remifentanil than in the fentanyl groups: with propofol 50.7 +/- 13.6s (mean +/- SD) versus 74.9 +/- 27.0s (P < 0.01), with thiopental 42.9 +/- 16.8s versus 77.2 +/- 27.8s (P < 0.01) and with etomidate 54.7 +/- 17.6s versus 72.3 +/- 24.0s (P < 0.05). The times to respiratory arrest or for the syringe to fall were significantly shorter with remifentanil than with fentanyl for propofol and for thiopental, but not for etomidate. In terms of dosages per kg body weight necessary to achieve unresponsiveness, less propofol (-29%, P < 0.05), thiopental (-25%, P < 0.05) or etomidate (-32%, P < 0.01) was necessary with remifentanil than with fentanyl. Haemodynamic responses to tracheal intubation were controlled more effectively with remifentanil. However, within the remifentanil groups, mean arterial pressure significantly decreased during induction: -26% with propofol, -181% with thiopental and -14% with etomidate (all P < 0.01). CONCLUSIONS: During anaesthetic induction, a remifentanil infusion of 0.5 microg kg(-1) min(-1) over 5 min is a suitable alternative to a 1.5 microg kg(-1) bolus dose of fentanyl: induction times are shorter with reduced amounts of propofol, thiopental or etomidate.     

Biphasic EEG changes in relation to loss of consciousness during induction with thiopental, propofol, etomidate, midazolam or sevoflurane

The time course of four EEG effect variables, amplitude in the2–5 Hz and in the 11–15 Hz band, spectral edge frequency95% (SEF95), and bispectral index (BIS), in response to increasingconcentrations of thiopental, propofol, etomidate, midazolam,or sevoflurane during a 10 min induction of anaesthesia wasstudied in 25 patients to determine the existence of a biphasiceffect and to study the relationship of the EEG effect to themoment of loss of consciousness. A biphasic effect, that is,an initial increase of the effect variable followed by a decreaseat higher concentrations, during the transition from consciousnessto unconsciousness was found in EEG amplitude (both frequencybands) and in SEF95 for all anaesthetics except midazolam. Therewas a concentration-related decrease in BIS for all anaesthetics.There was no consistent relationship between the time of occurrenceof the peak EEG effect, or the value of the EEG variable andthe moment of loss of consciousness. With rapidly changing drugconcentrations during the induction of anaesthesia, none ofthese EEG effect variables could be correlated to the momentof loss of consciousness. Br J Anaesth 2001; 86: 354–60     

Computer simulation of intracranial pressure changes during induction of anesthesia: comparison of thiopental, propofol, and etomidate

We have developed a computer model of cerebrovascular hemodynamics that interacts with a pharmacokinetic drug model. We used this model to examine the effects of various stimuli occurring during anesthesia on cerebral blood flow (CBF) and intracranial pressure (ICP). The model is a seven-compartment constant-volume system. A series of resistances and compliances relate blood and cerebrovascular fluid fluxes to pressure gradients between compartments. Variable arterial-arteriolar resistance (Ra-ar) and arteriolar-capillary resistance (Rar-c) simulate autoregulation and drug effects, respectively. Rar-c is also used to account for the effect of CO2 on the cerebral circulation. A three-compartment pharmacokinetic model predicts concentration-time profiles of intravenous induction agents. The effect-site compartment is included to account for disequilibrium between drug plasma and biophase concentrations. The simulation program is written in VisSim dynamic simulation language for an IBM-compatible personal computer. Using the model, we have predicted ICP responses during induction of anesthesia for a simulated patient with normal as well as elevated ICP. Simulation shows that the induction dose of intravenous anesthetic reduces ICP up to 30% (propofol > thiopental > etomidate). The duration of this effect is limited to less than 5 minutes by rapid drug redistribution and cerebral autoregulation. Subsequent laryngoscopy causes acute intracranial hypertension, exceeding the initial ICP. ICP elevation is more pronounced in a nonautoregulated cerebral circulation. Simulation results are in good agreement with the available experimental data. The presented model allows comparison of various drug administration schedules to control ICP.     

四种常用静脉麻醉药对老年病人血液动力学影响的比较

目的 探讨脑电双频指数(BIS)为50时，硫喷妥钠、丙泊酚、咪唑安定、依托咪酯用于老年病人全麻诱导的剂量及其对血液动力学的影响。方法 65岁以上的老年病人48例，随机分为四组：硫喷妥钠组，丙泊酚组，咪唑安定组，依托咪酯组。四组均缓慢静注，并且用HXD-1型脑电监测仪测量每例病人的BIS。当BIS逐渐下降至50时停止静注，分别于注药前、注药后1、3、5、10min用Rheo Cardio Monitor连续非创伤性血液动力监测仪记录和计算出血液动力学有关参数。结果 BP下降以丙泊酚组为显著。丙泊酚组和硫喷妥钠组的PEP/LVEF比值明显增加，但丙泊酚组＞硫喷妥钠组。除依托咪酯组以外其他各组的每搏指数(SD、心脏指数(CI)、射血速率(EV)和每搏功(LVP)均有不同程度的降低，但以丙泊酚组为显著。依托咪酯组体循环血管阻力(SVR)无明显变化，硫喷妥钠组和咪唑安定组均有不同程度的升高，以咪唑安定组为显著，丙泊酚组明显下降。舒张末容量(EDV)咪唑安定组明显下降，其他各组无明显变化。结论 四种静脉麻醉药对老年病人血液动力学的影响由大到小依次为丙泊酚＞咪唑安定＞硫喷妥钠＞依托咪酯。BIS为50时，老年病人各静脉麻醉药的等效剂量为硫喷妥钠4mg／kg、丙泊酚1．2mg／kg、咪唑安定0．16mg／kg、依托咪酯0．34mg／kg。对于心功能较差和血容量不足的老年病人全麻诱导，依托咪酯是首选的静脉麻醉诱导药。     

麻醉诱导期间咪达唑仑、异丙酚、依托咪酯及硫喷妥钠对脑血流速率的影响

目的 观察不同麻醉药物在麻醉诱导期间对大脑中动脉血流速率的影响.方法 40例病人随机分为4组(每组10例),麻醉诱导药物分别为咪达唑仑0.15mg/kg、异丙酚2mg/kg、依托咪酯0.3mg/kg和硫喷妥钠5mg/kg.给药3min后行气管内插管.麻醉维持采用1%七氟醚-66%氧化亚氮和氧气吸入,同时机械通气维持PETCO2在35～40mmHg.采用经颅多普勒监测仪(TCD),分别于诱导前和诱导1、2、3、5、10、15min测定大脑中动脉血流速率(V-MCA),同时记录动脉血压、心率及PETCO2.结果 给药后1min,异丙酚、依托咪酯和硫喷妥钠可使V-MCA明显降低(P＜0.05),而咪达唑仑组无显著变化(P＞0.05).气管插管后,4组病人的Vm-MCA,其中仅咪达唑仑组与基础值相比有显著差异(P＜0.05),而其他3组与基础值相比无统计学差异(P＞0.05).结论 对于非神经外科手术病人,诱导剂量的异丙酚、依托咪酯和硫喷妥钠对V-MCA的有一定程度的影响,而咪达唑仑影响较小;在对气管插管引起的脑血流速率波动的抑制方面咪达唑仑则作用较弱.