Ketamine eliminates propofol pain but does not affect hemodynamics during induction with double-lumen tubes

Background and objective  

Propofol injection during induction of anesthesia induces pain. Ketamine has been shown to reduce the injection pain. However, ketamine has unfavorable adverse effects, including increased secretion production and hemodynamic responses, which might induce pulmonary or hemodynamic adverse events, especially in patients undergoing lung surgery who require a double-lumen tube (DLT). The aim of this study was to determine whether ketamine can safely reduce propofol injection pain during induction of anesthesia for lung surgery.     

Premedication with oral dexmedetomidine alters hemodynamic actions of intravenous anesthetic agents in chronically instrumented dogs.

Dexmedetomidine (the D-stereoisomer of medetomidine), a highly selective alpha 2-adrenoceptor agonist, has been demonstrated to produce analgesia and sedation and attenuate hemodynamic responses to emergence from inhalational anesthetics, which suggests a potential use for this drug as a premedicant for general anesthesia. The authors examined hemodynamic interactions between dexmedetomidine and three commonly used intravenous anesthetic agents with markedly different hemodynamic effects. Conscious, chronically instrumented dogs received intravenous induction doses of ketamine, propofol, or etomidate, followed by continuous infusions of each drug at four different doses for 15-min intervals on different days. Studies in six separate groups (range, 9-12 dogs/group) with and without pretreatment with oral dexmedetomidine (20 micrograms/kg) were completed. Heart rate, arterial pressure, left ventricular pressure, rate of increase of left ventricular pressure at 50 mmHg (dP/dt50), and cardiac output were continuously recorded. Dexmedetomidine administration caused a significant (P less than 0.05) decrease in heart rate, rate-pressure product, left ventricular dP/dt50, and cardiac output. Dexmedetomidine abolished or attenuated the increase in heart rate, rate-pressure product, cardiac output, and arterial pressure produced during induction of anesthesia with ketamine. After the dexmedetomidine pretreatment, continuous infusion of ketamine caused no increase in heart rate or rate-pressure product. However, ketamine significantly reduced left ventricular dP/dt50 compared to control in dogs premedicated with dexmedetomidine. Except for a significant reduction in systemic vascular resistance, dexmedetomidine did not significantly affect the hemodynamic response to induction of anesthesia with propofol. Similarly, dexmedetomidine did little to alter the hemodynamic response to induction of anesthesia with etomidate.(ABSTRACT TRUNCATED AT 250 WORDS)     

七氟醚麻醉诱导在患儿全身麻醉中的应用

目的 观察七氟醚麻醉诱导与氯胺酮麻醉诱导在患儿全身麻醉中的应用.方法 选择30例3～7岁的患儿,随机均分为七氟醚组和氯胺酮组.观察两组诱导时间、苏醒时间、麻醉费用以及对循环、呼吸功能的影响.结果 七氟醚组诱导时间、苏醒时间短于氯胺酮组(P<0.01);七氟醚组血流动力学变化较氯胺酮组小(P<0.05);两组的呼吸抑制作用都较轻;七氟醚组入室时SpO<,2>低于氯胺酮组(P<0.05),但在可以接受的范围内.两组患儿的麻醉费用差异无统计学意义.结论 七氟醚麻醉诱导起效快,苏醒快,对循环呼吸影响小,手术室停留时问短,麻醉费用低廉,易于推广.     

Influence of Ketamine on Non-Pregnant Uterus in Vivo

This investigation was performed to evaluate the effect of ketamine anesthesia on non-pregnant uterine activity. Seven healthy non-pregnant women took part in the study. Anesthesia was induced with an i.v. bolus injection of ketamine 2 mg/kg and maintained with a continuous i.v. ketamine infusion, mean dosage 39 μg/kg/min. Before induction of anesthesia, each patient was placed in the lithotomy position, and a catheter fitted with two microtransducers for monitoring of intra-uterine pressures was fed through the cervix into the uterine cavity. For determination of plasma concentrations of ketamine and norketamine, venous blood samples were collected. The assay was based on a gas-liquid chromatographic technique. It was found that ketamine induced an increased uterine activity, both in basal tone and intensity of contractions. Only minor effects on the frequency were observed. This stimulatory effect was simultaneous with a hemodynamic stimulation with increases in heart rate and arterial blood pressure, and with the peak plasma concentration of ketamine.     

咪唑安定复合氯胺酮用于小儿基础麻醉的临床研究

目的　研究咪唑安定复合氯胺酮肌注或口服用于小儿基础麻醉的可能性。方法　 80例 1～ 8岁、ASAⅠ～Ⅱ级的患儿随机等分成四组 :A组 ,肌注氯胺酮 6mg/kg ;B组 ,肌注氯胺酮 4mg/kg +口服咪唑安定 0 2mg/kg ;C组 ,口服氯胺酮 5mg/kg +咪唑安定 0 5mg/kg ;D组 ,口服咪唑安定0 7mg/kg。观察各组麻醉诱导效果、循环呼吸变化及不良反应。 结果　 (1)B组与A组相比 ,起效更快 ,术中不良反应发生率更低 (P <0 0 5 ) ,而麻醉诱导效果无明显差异 (P >0 0 5 ) ;(2 )C组与A组相比 ,小儿更为合作 (P <0 0 1) ,HR增加不明显 (P >0 0 5 ) ,但起效更慢 (P <0 0 5 ) ,镇静程度不如后者 (P <0 0 5 ) ,但 80 %的患儿尚能与父母分离。结论　咪唑安定复合氯胺酮肌注用于小儿麻醉诱导要优于单纯肌注氯胺酮 ,而咪唑安定复合氯胺酮口服仍不失为一种可行的诱导方法。     

A ketamine-propofol admixture does not reduce the pain on injection compared with a lidocaine-propofol admixture

BACKGROUND: Propofol injection pain is a well-known problem in pediatric anesthesia. Premixture of lidocaine with propofol although effective does not abolish injection pain in all children. Promising results have been reported with pretreatment of the vein with ketamine. The purpose of this prospective, double-blind randomized, clinical trial with active control was to evaluate the efficacy of premixing propofol with ketamine in the prevention of injection pain in children. METHODS: After ethics committee and parental approval and children's assent, 116 children, aged 1-12 years, were randomly allocated to receive an IV induction dose of admixture of racemic ketamine 0.5 mg x ml(-1) (ketamine group) or lidocaine 1 mg x ml(-1) in propofol 10 mg x ml(-1) (lidocaine group). The outcome measures were signs and symptoms of injection pain (primary outcome: the incidence of injection pain), hemodynamic and respiratory parameters, and adverse effects during anesthesia induction (secondary outcomes). RESULTS: Patients' characteristics were similar in the two groups. Fewer children (13/58) in the lidocaine group than in the ketamine group (26/58) (mean difference 23%, 95% CI for difference 6-40%, P = 0.018) developed pain on injection of propofol. There were no differences in hemodynamic parameters between the two groups. One child in the lidocaine group developed laryngospasm, but no other adverse events were recorded. Conclusions: Injection pain was twice as common with ketamine-propofol admixture than with lidocaine-propofol admixture.     

Comparison of propofol versus ketamine for anesthesia in pediatric patients undergoing cardiac catheterization.

Intravenous propofol was compared with ketamine in 20 pediatric patients undergoing cardiac catheterization. The study patients were randomly assigned to treatment groups so that 10 patients received ketamine and 10 patients received propofol. The hemodynamic responses and recovery characteristics of the two groups were compared. On induction of anesthesia, seven patients in the propofol group experienced a transient decrease in mean arterial blood pressure greater than 20% of baseline accompanied by mild arterial desaturation in four patients. Only one patient in the ketamine group experienced such a decrease in arterial blood pressure. This was the only significant difference (P less than 0.05) in hemodynamic effects between the two groups. Time to full recovery (mean +/- SD) was significantly less in the propofol group (24 +/- 19 min vs 139 +/- 87 min, P less than 0.001). In the ketamine group only, significant correlations (P less than 0.05) included time to full recovery with duration of anesthetic (r = 0.71) and time to full recovery with total drug dose per kilogram (r = 0.82). The authors conclude that propofol anesthesia is a practical alternative for pediatric patients undergoing elective cardiac catheterization and may be preferable to ketamine because of the significantly shorter recovery time.     

The effect of propofol-ketamine anesthesia on hemodynamics and analgesia in comparison with propofol-fentanyl

Propofol (Diprivan), a modern intravenous hypnotic, produces a reduction in both cardiac index (CI) and mean arterial pressure (MAP). Ketamine (Ketanest), a potent analgesic, in contrast, causes an increase in MAP and CI. The aim of the present study was to investigate whether the combination of propofol and ketamine can give better hemodynamic stability during the induction and maintenance of general anesthesia than propofol used with fentanyl, whose cardiodepressant actions may cumulate. METHODS. For induction of general anesthesia 10 patients (ASA I and II) each received 3-5 boluses of propofol (0.5 mg.kg-1 during 35 s until predetermined level of anesthesia was reached (stage D2/E0 according to [20]) followed by a continuous propofol infusion (0.120 mg.kg-1.min). Fentanyl 0.1 mg was administered to each patient in group A for induction of anesthesia and again if evident pain was present. In group B ketamine was given following a pharmacokinetic model based on computer-simulated calculation. After an initial bolus of 38 mg injected within 2 min further doses of 42 mg, 35 mg, 32 mg and 28 mg ketamine were administered over 30 min at a time. Signs of evident pain were treated by means of supplementary doses of 0.5 mg.kg-1. RESULTS. In both groups a moderate drop of MAP was observed after the induction of general anesthesia. Two patients in each group showed a distinct decrease in MAP (-32%). The heart rate dropped slightly (-9%) in group A, but did not change in group B. Following intubation the MAP rose by less in group A (+8%) than in group B (+21%). After the beginning of the operation the group treated with propofol/fentanyl showed major hemodynamic changes; in particular, bradycardia with less than 40 bpm was observed in more patients than in the propofol/ketamine group. Postoperatively, fewer patients in group B required rescue doses of analgesics (1 of 10) than these in group A (7 of 10), though vigilance was better in group B. DISCUSSION. The dose of ketamine administered during the induction of general anesthesia may have been not high enough to neutralize the cardiodepressant effect of propofol. But during the maintenance of anesthesia there was in fact better hemodynamic stability in group B than in group A as a result of the neutralization of opposing actions. Fentanyl even intensified the fall in MAP after propofol. Patients in group B showed better vigilance as well as better pain relief postoperatively. The population of the fentanyl group was obviously more deeply sedated and analgesia was still inadequate. In our study general intravenous anesthesia with propofol and ketamine offered the advantages of better analgesia, a higher state of vigilance and the absence of respiratory depression during the postoperative phase compared with the combination of propofol and fentanyl.     

Efficacy of ketamine and midazolam as co-induction agents with propofol for laryngeal mask insertion in children

Objectives: Use of midazolam and ketamine lowers the induction dose of propofol (co‐induction) producing hemodynamic stability. Background: Large doses of propofol needed for induction and laryngeal mask (LM) insertion in children may be associated with hemodynamic and respiratory effects. Co‐induction has the advantage of reducing dose and therefore maintaining hemodynamic stability. Aim: To examine the effect of co‐induction on hemodynamics, LM insertion and recovery in children. Methods/Materials: A prospective, randomized, double‐blind, controlled study was conducted in 60 ASA I/II children, age 1–8 years. Normal saline, ketamine 0.5 mg·kg^?1, midazolam 0.05 mg·kg^?1 were administered in groups P (propofol), PK (propofol–ketamine) and PM (propofol–midazolam), respectively, 2 min prior to the administration of the induction dose of propofol. Propofol 3.5 mg·kg^?1 (group P) or 2.5 mg·kg^?1 (groups PK and PM) was used for induction, LM inserted 30 s later and insertion conditions assessed. Heart rate and blood pressure were recorded immediately after propofol bolus, then every min till 2 min after LMA insertion. Recovery was assessed using Steward’s Score. Result: In group P, systolic blood pressure (SBP) showed a significantly greater decrease compared to group PK and group PM (P < 0.005). Only 5% of patients in groups PK and PM showed >20% fall in SBP compared to 89% in group P (P < 0.005). More children in groups PK and PM had acceptable conditions for LM insertion compared to group P (P < 0.05). The time to achieve Steward Score of 6 was longer in groups PK and PM compared to group P (P < 0.005). Conclusion: In children, the combination of propofol with ketamine or midazolam produces stable hemodynamics and improved LM insertion conditions but is associated with delayed recovery.     

Intravenous ketamine attenuates injection pain and arterial pressure changes during the induction of anesthesia with propofol: a comparison with lidocaine

Objective: To compare the effects of lidocaine and ketamine pretreatment on injection pain and hypotension due to propofol induction. Design: Double blinded randomized controlled clinical trial. Place and Duration of the Study: Department of Anesthesiology, Surgical Intensive Care Unit and Pain Management, Dow University of Health Sciences and Civil Hospital, Karachi from February 2005 to December 2005. Patients and Methods: One hundred patients, age 20-60 years, of either gender, ASA I and II scheduled for elective gynaecological, urological, orthopedic or general surgical procedures under general anesthesia were randomly allocated into two groups i.e. group A to receive ketamine 0.5 mg/kg in volume of 2 ml with venous occlusion and group B to receive 2 ml of 1% lidocaine with venous occlusion as pretreatment before propofol induction. Venous occlusion was performed using rubber tourniquet after elevating the arm for 30 seconds, which was released 60 seconds after giving the pretreatment bolus and anesthesia was induced with propofol (2 mg/ml). Fifteen seconds after injection of 25%, the calculated dose of propofol and severity of injection pain was evaluated. Heart rate (HR) and noninvasive blood pressure were recorded pre-operatively, just before propofol induction, after propofol induction, immediately after intubation and 3 minutes after intubation. Results: Comparing the lidocaine group, the intensity and incidence of pain after propofol injection was lower in ketamine group but remained statistically insignificant. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly higher in ketamine group after induction with propofol. The maximum fall in SBP from baseline in ketamine group was 16% and 29.1% in lidocaine group, while maximum decrease in DBP in ketamine group was found to be12.66% vs. 26.47% in lidocaine group. There was no significant change in heart rate from baseline in either group. Conclusion: Ketamine pre-treatment with venous occlusion is an effective method in reducing pain and providing hemodynamic stability after propofol induction.     

Hemodynamic stability during induction of anesthesia and tracheal intubation with propofol plus fentanyl, ketamine, and fentanyl-ketamine

Purpose. This study was conducted to investigate hemodynamic and cardiac stability during anesthesia induction and intubation, using propofol plus fentanyl, propofol plus ketamine, and propofol plus fentanyl and ketamine. Methods. Forty-five adult patients were randomly allocated to one of three groups according to the agents used for induction: propofol (2 mg/kg) plus fentanyl (3 μg/kg) (PF), propofol (2 mg/kg) plus ketamine (0.1 mg/kg) (PK), and propofol (2 mg/kg) plus fentanyl (3 μg/kg) plus ketamine (0.1 mg/kg) (PFK). Hemodynamic responses were assessed by measuring changes in blood pressure (BP), heart rate (HR), and cardiac output (CO; using dye dilution combined with pulse dye densitometry [PDD]). Results. BP and HR changes during the induction of anesthesia tended to be greater in the PK group than in the PF and PFK groups. After the injection of propofol, the cardiac index (CI) fell significantly below baseline values in the PF and PFK groups, but remained unchanged in the PK group. After tracheal intubation, BP and HR increased significantly only in the PF and PK groups, and reached a level significantly above baseline values only in the PK group. The CO responses to tracheal intubation were: PK group > PF group > PFK group. Conclusion. A combination of propofol plus fentanyl plus ketamine would provide greater reduction of fluctuations in hemodynamic variables associated with induction of anesthesia and tracheal intubation than combinations of propofol plus fentanyl or propofol plus ketamine. Received: January 22, 2001 / Accepted: June 19, 2001     

Anesthetic management by total intravenous anesthesia with propofol, pentazocine and ketamine

BACKGROUND: The authors evaluated the efficacy of anesthetic management by total intravenous anesthesia with propofol, pentazocine and ketamine. METHODS: Thirty-five patients for mastectomy were anesthetized by propofol, pentazocine and ketamine. Patients were divided into two groups by age; one is patients under 61 years of age and the others are patients above 61 years. Analysis was made retrospectively. Anesthesia was induced with propofol and ketamine and was maintained with propofol infusion and intermittent administration of vecuronium with 40% oxygen in air. Pentazocine was administrated as a bolus dose before incision. RESULTS: There were no differences in the patient background except age and height between the two groups. After induction of anesthesia, systolic and diastolic blood pressures decreased compared with those before induction in both groups. Systolic and diastolic blood pressures and heart rate increased after tracheal intubation, but the hemodynamics remained stable after the start of surgery. The induction and maintenance doses of propofol were not different between the two groups. Patients above 61 years had smaller dosage of pentazocine compared with those in patients under 61 years. The dosage of ketamine was not different between two groups. Awakening time in about 80% of patients was within 15 minutes and is not different between the two groups. Postoperative pain relief was good in both groups. Incidence of nausea and vomiting was 25% and was not the different between the two groups. CONCLUSIONS: Total intravenous anesthesia with propofol, pentazocine and ketamine would be useful to stabilize hemodynamic state, to obtain rapid recovery and to provide effective postoperative pain relief.     

Comparison of sevoflurane and ketamine for anesthetic induction in children with congenital heart disease

Background:  Sevoflurane is widely used in pediatric anesthesia for induction. Ketamine has been preferred in pediatric cardiovascular anesthesia. Aim of this study was to compare the hemodynamic effects and the speed of ketamine and sevoflurane for anesthesia induction in children with congenital heart disease.
Materials and methods:  Children with congenital heart disease undergoing corrective surgery were included in the study. After oral premedication with midazolam (0.5 mg·kg⁻¹), anesthesia induction was started with 5 mg·kg⁻¹ intramuscular ketamine (group K). In the second group, induction was achieved with sevoflurane (group S); the first concentration was 3% and increased after every three breaths. Intravenous access time and intubation times were enrolled for each child. Hemodynamic data and oxygen saturation were recorded every 2 min and any event during induction period was also noted.
Results:  Forty-seven children were included in the study; 23 in group K and 24 in group S. Heart rates and oxygen saturation values were similar between groups during the study. No difference was found between intravenous access time and intubation times. However, blood pressure levels were significantly lower in group S after recording baseline values till the intubation time (at 4, 6, and 8 min). Respiratory complications observed during the study were mild and were less frequent in group K than in group S (4 vs 13).
Conclusion:  Ketamine appears a good alternative for induction in patients with congenital heart disease. It permits preservation of hemodynamic stability with minimal side effects.     

Optimum dose of ketamine for prevention of postanesthetic shivering; a randomized double-blind placebo-controlled clinical trial

Our objective was to investigate the efficacy and the optimum dosage of ketamine for post anesthetic shivering prevention. One-hundred and twenty patients (ASA I-II) scheduled for elective orthopedic surgery were randomly allocated to receive ketamine in 3 groups ; groups A (0.125 mg/Kg), groups B (0.25 mg/Kg) and C (0.5 mg/Kg) along with those receiving 0.9% normal saline as the placebo group. Tympanic temperature was measured immediately after induction of anesthesia, 30 min after induction, before administration of the study drug and by the end of the surgery. The four groups did not differ significantly in their hemodynamic parameters and tympanic temperature. The frequency of shivering was significantly less in groups B (0.25 mg/Kg) and C (0.5 mg/Kg) than in groups A (0.125 mg/Kg) and D (placebo). In addition recovery, extubation time and hallucination was observed to be less in group B compared to group A. Prophylactic 0.25 and 0.5 mg/kg ketamine was found to be effective in preventing postanesthetic shivering with a better response observed with 0.25 mg/kg dosage.     

Low-dose intramuscular ketamine for anesthesia pre-induction in young children undergoing brief outpatient procedures

The authors sought to determine whether intramuscular ketamine (2 mg/kg) would facilitate inhaled induction of anesthesia in those children who are uncooperative. Thirty-five children were anesthetized with halothane and nitrous oxide for insertion of tympanotomy tubes. Twenty of those children were deemed by the anesthesiologist to be uncooperative and received 2 mg/kg of ketamine im prior to induction of anesthesia. The onset time (time from ketamine administration until induction of inhaled anesthesia could be started) was 2.7 +/- 0.3 min. The quality of the subsequent acceptance of inhaled induction with halothane was excellent in 61% of the patients and adequate in the remaining 39%. The recovery and discharge times were compared with those observed in 15 matched children who accepted induction of anesthesia via a mask without the use of ketamine. Recovery time was not prolonged, but home discharge was delayed by an average of 13 min in the ketamine group (P less than 0.04). Low-dose im ketamine was found to be an acceptable pre-induction drug in young children who are uncooperative for an inhaled induction of anesthesia.     

The effect of alfentanil versus ketamine on the intubation condition and hemodynamics with low-dose rocuronium in children

Purpose

We investigated the effect of alfentanil and ketamine on the intubation condition and hemodynamic parameters during propofol anesthesia with low-dose rocuronium in children.

Methods

Fifty-four children, aged 3–9 years undergoing tonsillectomy, were randomly allocated to receive either alfentanil 20 μg/kg (alfentanil group, n = 27) or ketamine 0.5 mg/kg (ketamine group, n = 27) 1 min before anesthesia induction. Anesthesia was induced with propofol 2.5 mg/kg and rocuronium 0.3 mg/kg and maintained with propofol infusion (6 mg/kg/h). The neuromuscular relaxation was monitored, and intubation conditions, hemodynamic changes, and recovery time were assessed.

Results

All patients were successfully intubated and there were no significant differences in the intubation conditions between alfentanil and ketamine groups. At the time of tracheal intubation, the median [inter-quartile range] twitch height was similar between two groups (37 [4–48] % in the alfentanil group vs. 29 [4–43.5] % in the ketamine group, p = 0.326).

Conclusions

This study showed that both ketamine 0.5 mg/kg and alfentanil 20 μg/kg provided adequate intubation condition during propofol induction with low-dose rocuronium in children. The mean arterial pressure and heart rate were higher in the ketamine group after propofol injection but they remained within the normal limit in both groups throughout the study period.     

Anesthesia for repair of ventricular septal rupture after acute myocardial infarction

A surgical patient with ventricular septal rupture after acute myocardial infarction is presented. The primary concern of general anesthesia was in the maintenance of systemic arterial pressure and reduction of afterload. General anesthesia was induced with a combination of fentanyl, ketamine, and propofol, which successfully suppressed fluctuations of hemodynamic variables associated with induction of anesthesia and tracheal intubation. Intravenous milrinone was used for inotropic support and reduction of systemic vascular resistance. The ventricular septal rupture was successfully repaired.     

Comparative study of 3 techniques for total intravenous anesthesia: midazolam-ketamine, propofol-ketamine, and propofol-fentanyl]

OBJECTIVE: To compare the characteristics of induction, maintenance and awakening for three techniques of combined total intravenous anesthesia (TIVA): propofol-ketamine, midazolam-ketamine and propofol-fentanyl. PATIENTS AND METHODS: Sixty patients were randomly assigned to three TIVA groups. Group 1 (n = 20) received midazolam, ketamine and vecuronium. Group 2 (n = 20) received propofol, ketamine and vecuronium. Group 3 (n = 20) received propofol, fentanyl and vecuronium. The variables compared were hemodynamic changes during induction and maintenance and upon awakening; time until awakening; and the incidence of postanesthetic complications. We also assessed whether propofol was better than midazolam at preventing the psychomimetic effects of ketamine. RESULTS: The demographic characteristics of the three groups were similar. Hemodynamic variables were most stable in group 2. Perfusion of midazolam-ketamine was accompanied by a significantly higher number of hypertensive peaks. Time to awakening was significantly shorter in Group I (11.8 +/- 5 min) than in group 2 (20.2 +/- 12.5 min); in group 2 time to awakening was 16.6 +/- 5.6 min. Eight patients in group 1, 5 in group 2 and 1 in group 3 reported having bad dreams, the difference between groups 1 and 3 reaching statistical significance. No patient experienced hallucinations and all reported satisfaction with the anesthetic technique used. CONCLUSIONS: TIVA with ketamine and propofol is comparable to the most commonly used combination of propofol and fentanyl and may be an appropriate choice when hemodynamic stability is of great importance; withdrawal 15 min before ending surgery prevents prolonged awakening. Perfusion of midazolam-ketamine is not recommendable for scheduled surgery because it induces too many hypertensive peaks. Although neither midazolam nor propofol completely prevents the psychomimetic effects of ketamine, such effects are not so severe that patients reject the anesthetic technique used.     

Optimal dosage strategies in total intravenous anesthesia using propofol and ketamine

The combination of propofol and ketamine for total intravenous anesthesia was investigated; the intention was to minimize the side effects of each drug by the concomitant application of the other drug. METHODS. Twenty patients scheduled for lower abdominal interventions were divided into two groups. In the first group anesthesia was induced and maintained by a simple administration regimen based upon pharmacokinetic principles. Ketamine and propofol were given as bolus injections (60 mg each) with a time interval of 60 s for induction followed by a two-step infusion regimen for propofol (15.5 mg/min) and later on by an additional ketamine infusion (1-2 mg/min). Bolus injections (20 mg) of ketamine were administered to increase the depth of anesthesia if necessary (Fig. 1). The second group received propofol and ketamine by microprocessor-controlled infusion pumps requiring the anesthetist to operate a single dial to preset the desired blood levels of both drugs according to the needs of the individual patient (Fig. 2). RESULTS. There were no difference (Table 1) between the two groups in the demographic data of the patients or duration of surgery (30-120 min). The total doses of propofol (750 +/- 262 vs 624 +/- 468 mg) and ketamine (158 +/- 41 vs 99 +/- 48 mg) were smaller in the computer-controlled infusion group, though this difference just failed to be significant. The hemodynamic changes during induction were minor, with a small nonsignificant increase in all parameters (Fig. 3) for 10 min. The controllability of the pharmacodynamic effects of both drugs during anesthesia was very satisfactory in the computer-assisted infusion group and quite satisfactory in the first group. There were no psychic disturbances during induction of or recovery from anesthesia. Respiration was adequate within a few minutes after the end of surgery. The patients were awake about 10 min later and fully oriented after 20 min. No major side effects were observed with this anesthetic technique. CONCLUSION. Total intravenous anesthesia with propofol and ketamine proved to be very satisfactory from a clinical point of view. The major known side effects of propofol (reduced hemodynamics during induction) and ketamine (psychic disturbances and cardiovascular stimulation) were absent and respiratory function was adequate after the end of surgery. This technique, therefore, can be used in risk patients and under disaster conditions when i.v. access is the only possible route of drug administration. The use of computer-assisted infusion pumps markedly enhances handling and controllability of total i.v. anesthesia.     

Effects of low dose ketamine before induction on propofol anesthesia for pediatric magnetic resonance imaging

BACKGROUND: We aimed to investigate effects of low dose ketamine before induction on propofol anesthesia for children undergoing magnetic resonance imaging (MRI). METHODS: Forty-three children aged 9 days to 7 years, undergoing elective MRI were randomly assigned to receive intravenously either a 2.5 mg x kg(-1) bolus of propofol followed by an infusion of 100 microg x g(-1) x min(-1) or a 1.5 mg x kg(-1) bolus of propofol immediately after a 0.5 mg x kg(-1) bolus of ketamine followed by an infusion of 75 microg x kg(-1) x min(-1). If a child moved during the imaging sequence, a 0.5-1 mg x kg(-1) bolus of propofol was given. Systolic and diastolic blood pressures, heart rate, peripheral oxygen saturation and respiratory rates were monitored. Apnea, the requirement for airway opening maneuvers, secretions, nausea, vomiting and movement during the imaging sequence were noted. Recovery times were also recorded. RESULTS: Systolic blood pressure and heart rate decreased significantly in the propofol group, while blood pressure did not change and heart rate decreased less in the propofol-ketamine group. Apnea associated with desaturation was observed in three patients of the propofol group. The two groups were similar with respect to requirements for airway opening maneuvers, secretions, nausea-vomiting, movement during the imaging sequence and recovery time. CONCLUSIONS: Intravenous administration of low dose ketamine before induction and maintenance with propofol preserves hemodynamic stability without changing the duration and the quality of recovery compared with propofol alone.