Pulse transit time reveals drug kinetics on vascular changes affected by propofol

Pulse transit time (PTT) is the duration in which a pulse wave travels between two arterial sites within the same cardiac cycle. The aim of our study is to use PTT to examine propofol's effects on the vascular system. Methods. We collected data from 50 healthy women, between 28 and 51 years old, who underwent gynaecological surgery under general anaesthesia. The general anaesthesia was induced with propofol injection (2 mg/kg). PTT measurements were obtained from the R-wave of electrocardiogram and the pulse wave of photoplethysmograph. Two PTT values were obtained; one before (the control) and the other after propofol injection. The results were analysed by Student's t-test. Results. After propofol injection, the PTT was prolonged. The change in the PTT value from that of baseline was significant statistically (P < 0.05, by Student's t-test). The PTT change over time correlated with the degree of vasodilatation over time. Monitoring of PTT not only revealed the magnitude of vascular changes but also demonstrated the onset of vascular dilation, its peak and duration. We conclude that PTT is a useful guide in monitoring the drug kinetics of propofol.     

Propofol-induced vascular permeability change is related to the nitric oxide signaling pathway and occludin phosphorylation

The present study was undertaken to elucidate the mechanism of intra-arterial propofol-induced vascular permeability change resulting in tissue edema. The mechanism of propofol-induced hyperpermeability was examined in a rat femoral artery injection model. Vascular permeability was determined by measuring the Evans blue content of the dorsal skin of the infused limb at 15, 30, 45 and 60 min after propofol injection. The total content of the tight junction proteins occludin, ZO-1 and claudin-5 under experimental conditions was also determined by western blotting. Intra-arterial injection with propofol resulted in a marked dose-dependent increase in vascular permeability of the rat hindpaw. Pretreatment with 10 mg/kg of N-nitro-l-arginine methyl ester (l-NAME) but not aminoguanidine significantly inhibited the change in vascular permeability after challenge with propofol. Pretreatment with l-arginine and nitroprusside increased the propofol-induced permeability change. Intra-arterial injection of propofol significantly increased occludin phosphorylation after 15 min, which was consistent with the time profile of the vascular permeability change. l-NAME partially reversed the change in occludin phosphorylation, whereas aminoguanidine had no effect compared with that in the controls. Our observations indicate that nitric oxide (NO) is an important mediator in the induction of vascular permeability induced by propofol. Occludin phosphorylation is a determining factor in the vascular permeability change induced by propofol. NO synthase (NOS) inhibitors might be useful in the treatment of accidental intra-arterial injection of propofol, in the reduction of any adverse effects.     

Skin blood flow changes in anaesthetized humans: comparison between skin thermal clearance and finger pulse amplitude measurement

The effect of general anaesthesia on skin blood flow in the left hand, measured by a new non-invasive probe using the thermal clearance method was examined. A mercury silastic gauge was placed around the third left finger and the plethysmographic wave amplitude was recorded to measure changes in finger pulse amplitude. Heart rate (HR), mean arterial blood pressure (MABP) and skin temperature were also recorded. General anaesthesia was induced by droperidol and phenoperidine injection and propanidid infusion in eight female patients. Skin thermal clearance, plethysmographic wave amplitude, HR, MABP and skin temperature were 0.40 +/- 0.02 w X m-1 degree C-1, 9 +/- 1 mm, 98 +/- 5 beats X min-1, 12.50 +/- 0.93 kPa and 33.3 +/- 3.4 degrees C respectively. The minimal value of MABP was 9.58 +/- 1.06 kPa, whereas skin thermal clearance, plethysmographic wave amplitude, HR and skin temperature increased to 0.45 +/- 0.02 w X m-1 degree C-1, 29 +/- 3 mm, 110 +/- 4 beats X min-1 and 34.4 +/- 0.4 degrees C. Changes in skin thermal clearance correlated well with plethysmographic wave amplitude. Statistically significant changes in these two parameters occurred before significant change in HR, MABP or skin temperature. The results show that the new non-invasive probe using the thermal clearance method appears to be a useful device for measuring cutaneous microcirculation in anaesthetized humans, and responds more quickly than change in skin temperature, which is a delayed effect of skin blood flow change. Our results also show that the intensity of cutaneous vasodilatation induced by general anaesthesia did not relate to the vascular tone before anaesthesia.     

A long-term porcine model for measurement of gastrointestinal motility

Animal models have become an essential tool in the investigations of gut motility under experimental conditions. To determine the influence of various anaesthetic drugs on the motility pattern of the gastroduodenal tract, a new long-term model has had to be developed for allowing measurements in conscious and unrestrained as well as in sedated and analgosedated pigs. Since mechanical ventilation influences gut motility, it was necessary that this animal model enabled the investigation of the effect of drugs causing sedation and analgosedation during spontaneous breathing. Seven male, castrated pigs, German landrace, 32-40 kg bodyweight (BW) were investigated in this study. After habituation of the pigs to local housing conditions over 5 days, the animals were trained over 4 days to prepare for experimental situations and investigators. Pigs were inserted with a central venous catheter and with percutaneous enterogastrostomy (PEG) under general anaesthesia. Intestinal motility was measured by intraluminal impedancometry. The catheter was introduced over the PEG into the stomach and positioned into the duodenum by duodenoscopy. Measurements were done in conscious, unrestrained pigs and with sedated, and analgosedated animals on subsequent days. The habituation and training of the pigs to the investigators and for the laboratory conditions took between 7 and 9 days. The initial anaesthesia protocol for the instrumentation using remifentanil/propofol led to pyloric spasm and was thus unsuitable for duodenal intubation with an endoscope. In contrast, a combination of ketamine/propofol enabled this procedure. It was practicable to measure gut motility in conscious, unrestrained pigs. Spontaneous breathing was sufficient under propofol sedation and analgosedation using fentanyl-propofol. Systematically local application of polividon iodine in the area of the subcutaneous catheters avoided the necessity of using systemic prophylactic antibiotics. In conclusion, the habituation and training for 9 days enabled the measurement of gut motility by intraluminal impedancometry in conscious pigs. The insertion of the catheter was done during general anaesthesia using a combination of propofol and ketamine. For the future determination of gut motility performed under general anaesthesia, each sedation and analgosedation concept has to be evaluated to see whether it allows spontaneous breathing or whether mechanical ventilation is necessary.     

Cognitive and functional competence after anaesthesia in patients aged over 60: controlled trial of general and regional anaesthesia for elective hip or knee replacement.

OBJECTIVE--To determine the influence of general or regional anaesthesia on long term mental function in elderly patients. DESIGN--Prospective study of patients randomly allocated to receive general or regional anaesthesia. SETTING--The patients'' homes and a large teaching hospital in Cardiff. SUBJECTS--146 Patients aged 60 and over scheduled for elective hip or knee replacement. MAIN OUTCOME MEASURES--Scores achieved in tests of cognitive function and functional competence. RESULTS--72 Patients were allocated to receive general anaesthesia and 74 regional anaesthesia. Anaesthetic technique did not influence the duration of the operation, time to mobilisation postoperatively, requirements for analgesia after the operation, or duration of stay in hospital. Three months after the operation there was an improvement in the score for the recognition component (76 ms, 95% confidence interval 9 to 144) and the response component (82 ms, 5 to 158) of the choice reaction time in the group receiving general anaesthesia compared with the group receiving regional anaesthesia. This was the only significant difference between the two groups in the assessments of cognitive and functional competence. Eleven patients receiving regional anaesthesia and 12 receiving general anaesthesia reported that their memory and concentration were worse than before the operation, but this was not confirmed by testing. CONCLUSION--Cognitive and functional competence in elderly patients was not detectably impaired after either general or regional anaesthesia when attention was paid to the known perioperative influences on mental function.     

Intraperitoneal propofol and propofol fentanyl, sufentanil and remifentanil combinations for mouse anaesthesia

The combination of propofol and a rapid-acting opioid, such as fentanyl, sufentanil or remifentanil, is a relatively safe, total intravenous anaesthesia technique, commonly used in humans and which has been investigated in laboratory animals. The objective of this study was to evaluate these combinations for anaesthesia of mice by the intraperitoneal (i.p.) route. Sixty-seven mice, divided into groups of four, were used to test 28 combinations of propofol alone and propofol with fentanyl, sufentanil or remifentanil administered i.p. The dose ranges of drugs studied were propofol 50-200 mg/kg, fentanyl 0.2-0.4 mg/kg, sufentanil 0.05-0.1 mg/kg and remifentanil 0.2-1.0 mg/kg. The loss of righting reflex (RR) and the loss of pedal withdrawal reflex (PWR) were recorded along with the duration and quality of recovery. The results obtained in these studies were unpredictable. The same dose combinations of propofol and opioids were associated with different responses in different individuals. Higher doses did not induce loss of RR and PWR in all animals and were associated with high mortality rates. An adequate hypnotic level was only observed with higher doses of propofol. The synergistic effect of propofol and the opioids was not sufficient to allow surgical procedures. Animals that reached PWR loss showed tail rigidity, shaking limbs and scratched their heads with their forefeet. Higher opioid doses induced respiratory depression and higher death rates. The inconsistency between and within groups may be associated with the i.p. route. The results reported here show that the i.p. route is not appropriate for mouse anaesthesia using propofol alone or in combination with fentanyl, sufentanil or remifentanil.     

Relationship of bispectral index values, haemodynamic changes and recovery times during sevoflurane or propofol anaesthesia in rabbits

The aim of this study was to determine and compare the degree of hypnosis achieved during propofol or sevoflurane anaesthesia in rabbits using bispectral index (BIS), and to evaluate its usefulness as a predictor of both haemodynamic changes during anaesthesia and recovery times. Twenty adult male New Zealand White rabbits, average weight 4.4 +/- 0.4 kg, were used for this study. Animals were randomly allocated to one of two groups with 10 rabbits/group. An electroencephalographic recording was obtained from each conscious rabbit prior to drug administration. All animals received buprenorphine as a preanaesthetic medication (0.05 mg/kg, intravenous [i.v.]). Anaesthesia was induced with propofol (8 mg/kg, i.v.) in all animals; 10 rabbits were maintained with sevoflurane via inhalation (1 minimum alveolar concentration--end-tidal sevoflurane concentration of 3.7%--at a fresh gas flow rate of 3 L/min; group I), and 10 were maintained with i.v. propofol (0.6 mg/kg/min; group II). The rabbits were orotracheally intubated and spontaneous ventilation was maintained throughout the study (100% oxygen). After abdominal surgery through a ventral midline laparotomy, rabbits were allowed to recover from anaesthesia. Cardiovascular variables and BIS values were recorded at intervals throughout the procedure, as was the duration of recovery from anaesthesia. In both groups, mean BIS values were significantly decreased immediately after induction, compared with baseline values obtained during consciousness. Anaesthetic depth (evaluated by clinical observation) was similar in both groups; however, group II rabbits had significantly higher (P<0.001) BIS values from 30 s before incision until anaesthesia was discontinued. There was no significant difference in BIS recorded 1 and 5 min after incision as compared with values obtained 30 s before incision in either group. During sevoflurane or propofol administration, correlations were found between BIS values and mean arterial blood pressure (MABP), and between BIS values and heart rate (HR). Mean BIS values at discontinuation of administration of the anaesthetic agent were greater in group II (69.1 +/- 6.0) than in group I (49.3 +/- 2.2). However, recovery from anaesthesia was significantly longer in group II (38.4 +/- 7.2 min) than in group I (11.5 +/- 2.5 min). In conclusion, BIS can be used to differentiate between conscious and unconscious states during anaesthesia in rabbits. BIS values derived from an electroencephalogram at the end of anaesthesia were not useful for predicting the speed of anaesthetic recovery in sevoflurane or propofol-anaesthetized rabbits undergoing abdominal surgery. Despite the correlation found between BIS and haemodynamic parameters, its usefulness as a predictor of clinically important changes in arterial blood pressure and HR in anaesthetized rabbits was limited.     

The Narcotrend Index: classification algorithm, correlation with propofol effect-site concentrations, and comparison with spectral parameters.

A reliable assessment of the depth of hypnosis during sedation and general anaesthesia using the EEG is a subject of current interest. The Narcotrend Index implemented in the latest version 4.0 of the EEG monitor Narcotrend provides an automatic classification of the EEG on a scale ranging from 100 (awake) to 0 (very deep hypnosis, EEG suppression). The classification algorithms implemented in the EEG monitor Narcotrend are described. In a study the correlation of the propofol effect-site concentration with the Narcotrend Index and with the traditional spectral parameters total power, relative power in the standard frequency bands delta, theta, alpha, and beta, median frequency, 95% spectral edge frequency, burst-compensated spectral edge frequency, and spectral entropy was investigated. The Narcotrend Index had the highest average correlation with the propofol effect-site concentration and the smallest variability of the individual correlation values. Moreover, the Narcotrend Index was the only parameter which showed a monophasic trend over the whole investigated time period. The Narcotrend monitor can make a significant contribution to the improvement of the quality of anaesthesia by adjusting the dosage of hypnotics to individual patient needs.     

Effect of anaesthesia on the pattern of breathing.

The pattern of breathing of male rats was studied after stimulating respiration with carbon dioxide at different levels of general anaesthesia. Anaesthesia was induced by the inhalation of halothane or by the i.p. injection of urethane. Ventilation values were measured in intubated rats in body plethysmograph. It was found that a linear relationship between minute ventilation and tidal volume was maintained during the decrease of minute ventilation due to deepening of anaesthesia. The slope of the relationship after stimulating respiration with carbon dioxide also diminished during deeper anaesthesia. The duration of inspiration did not alter significantly, despite marked changes in tidal volume. Tidal volume correlated with the duration of expiration at different anaesthesia levels. In vagotomized rats, the duration of expiration shortened as ventilation was depressed by deepening anaesthesia.     

DNA fingerprinting data and the analysis of population genetic structure by comparing band-sharing patterns

Genetic isolation among populations can be effectively investigated by multilocus DNA fingerprinting. If populations have diverged, it is expected that the mean proportion of bands shared by individuals from the same population, Bw, exceeds the corresponding mean, Bb, calculated from pairs of individuals from distinct populations. A problem arises in deciding whether any difference between Bw and Bb is statistically significant. In fact, any two band-sharing data (bij), contributing to Bw or Bb, are not independent if they share a common individual (like bij and bjl). This prevents a correct application of parametric tests, such as the Student's t-test. Recently, a modification of this test has been proposed that should avoid the independence problem. Using a large number of samples of fingerprints, simulated from an appropriate 'genetic' model, under a wide range of conditions, we compared the performances of the Student's t-test, the modified t-test and five new permutation tests, where individuals, rather than bij values, are permuted. We found that: (i) the Student's t-test can be very permissive, rejecting too often the null hypothesis when true, but is correct or conservative in certain cases; (ii) the modified t-test is extremely conservative when the null hypothesis is true and very inefficient otherwise; (iii) all five permutation tests are strictly correct, provided that individuals are ordered randomly on gels; and (iv) in this case, the permutation tests are equally efficient, and are not inferior to the Student's t-test when the latter is approximately correct and provides a fair benchmark.     

The effect of <Emphasis Type="Italic">UGT1A9</Emphasis>, <Emphasis Type="Italic">CYP2B6</Emphasis> and <Emphasis Type="Italic">CYP2C9</Emphasis> genes polymorphism on individual differences in propofol pharmacokinetics among Polish patients undergoing general anaesthesia

Propofol (2,6-diisopropylphenol) is one of the safest and most commonly used anaesthetic agents for intravenous general anaesthesia. However, in clinical practice, a large inter-individual variability in response to propofol is observed. To limit the risk of adverse effects, pharmacogenetic investigations are recommended. The aim of our study was to verify the impact of genetic changes c.516G>T in the CYP2B6, c.98T>C in the UGT1A9 and c.1075A>C in the CYP2C9 genes on the individual propofol pharmacokinetic profile in the Polish patients undergoing general anaesthesia. Eighty-five patients from the Department of Anaesthesiology and Intensive Therapy, Regional Hospital in Poznan, Poland, anaesthetised with propofol for surgery, were enrolled in the study. We have genotyped CYP2B6, UGT1A9 and CYP2C9 polymorphisms with the use of pyrosequencing. HPLC measurements of propofol plasma concentration were applied for a pharmacokinetic analysis of the anaesthetic. We identified poor (20), intermediate (42) and rapid (23) metabolisers of propofol, which constituted 24%, 49% and 27% of the group, respectively. Homozygotes c.516 T/T in the CYP2B6 gene were statistically more often found in the rapid metabolisers group (p?<?0.05). However, polymorphisms c.98T>C in the UGT1A9 and c.1075A>C in the CYP2C9 genes did not affect the pharmacokinetic profile of propofol. The mean propofol retention time (MRT) correlated with the patient’s body mass index (BMI) (p?<?0.05). From all the analysed changes, only polymorphism c.516G>T in the CYP2B6 gene and BMI affect the metabolism rate of propofol and may play an important role in the optimisation of propofol anaesthesia.     

Is pulse transit time useful in differentiating respiratory events for patients with a sleep breathing disorder? A pilot study

Variation of inspiratory effort in sleep disordered breathing induces the oscillation in blood pressure, which corresponds inversely to pulse transit time (PTT). This study evaluated the feasibility of PTT as a visual parameter for differentiating respiratory events in patients with a sleep breathing disorder. Sixteen patients who complained of snoring and sleep apnea were booked into the study. Polysomnographic data of Zopiclone induced daytime sleep were analyzed, PTT and intraesophageal pressure (Peso) were assessed for each respiratory event. With respect to Peso, the total accuracy of PTT was 51.8% for 1266 events. The relatively high coincidence rate could be observed in obstructive events (57.1%), with crescendo Peso pattern (71.5%), in lateral position (82.2%). Pulse transit time oscillation could only partly reflect respiratory rhythm to some degree (56.5%). Absolute PTT value presented a poor relationship with respiratory effort. Pulse transit time coincided well with crescendo Peso in lateral position for obstructive events. Swings in PTT could only partly fit respiratory wave data. Absolute PTT value and its change could not reflect respiratory effort. Although PTT is a non-invasive and convenient way for assessing inspiratory effort, its variable sensitivity to different events, respiratory patterns, positions, different patients and other situations, limit its feasibility. Further work is required.

     

Effect of propofol in altering pentylenetetrazol induced seizure threshold in rats

The present study was undertaken to evaluate the role of propofol in altering pentylenetetrazol induced seizure threshold in rats. Total 42 Wistar rats were used to evaluate different parameters (onset of action, duration of seizure, seizure severity score and number of seizure) following propofol injection. The present results showed that there was significant reduction in the time required for onset of seizure in propofol treated groups following PTZ treatment. If treated with propofol alone (2 and 5 mg/kg), there was no significant difference as compared to controls. In seizure severity score assessment, there was no significant difference with various doses of propofol alone treated groups, but the difference was observed in propofol (2 and 5 mg/kg) treated groups following PTZ treatment. Duration of seizure also significantly increased in propofol (5 mg/kg) treated group, but at 2 mg/kg of propofol treatment, no significant difference was observed. The present results showed that propofol ameliorate seizure threshold and caused prolongation of duration of seizure. However, further study and trials are needed to confirm the present results.     

Anaesthesia and the acute phase protein response in children undergoing circumcision

Concentrations of acute phase proteins (CRP: C-reactive protein, albumin) change during surgery. We investigated the acute phase response to circumcision and the effects of anaesthesia on this response. The children were divided into four groups; group 1 (intratracheal general anaesthesia, n=40), group 2 (general anaesthesia with mask, n=20), group 3 (ketamine, n=20), group 4 (local anaesthesia, n=35). Blood samples were obtained, 24 hours before circumcision, after premedication, and 24 hours after circumcision. CRP and albumin before circumcision were comparable for all groups. There was no increase in CRP, and albumin remained steady throughout the study. No difference was observed among the groups, and related to anaesthesia. No responsiveness may be explained with the size of injured tissue or anatomical and histological type of preputium.     

Influence of gender on the onset and duration of rocuronium-induced neuromuscular block

Aims: To assess the influence of gender on the course of rocuronium-induced neuromuscular block following a single bolus dose of 2 x ED(95) (0.6 mg kg(-1)). Methods: Following the ethics committee approval and informed consent, 245 patients (121 men, 124 women) scheduled for elective general surgery under TIVA with muscle relaxation were studied. After rocuronium 0.6 mg kg(-1), the onset time for maximal depression of T(1), clinical duration until 25 % recovery and recovery index (T(1) from 25 to 75 %) were determined with TOF-Watch(R) SX accelerometric monitor. The data for male and female groups were compared with appropriate statistical tests (Student's unpaired t-test, Mann-Whitney Rank Sum Test and Fisher's exact test). Results: Men were significantly larger (p < 0.001) and heavier (p < 0.05) than women, but the body mass index was comparable (ns). The onset time was shorter in females [92.5 (SD 14.2) vs. 104.7 (12.2) s, p < 0.0001]. Clinical duration was increased in females [43.1 (7.9) vs. 31.3 (5.5) min; p < 0.0001], while the recovery index was identical in both groups [14.7 (5.0) min in females and 14.8 (4.0) min in males; ns]. Conclusions: Women are more sensitive than men to the dose 0.6 mg kg(-1) of rocuronium. Under the study conditions described, the onset time was shortened and the clinical duration increased in female patients. This suggests that the routine dose of rocuronium should be reduced in women.     

An evaluation method for hematological and clinico-biochemical values in aged F 344 rats on chronic toxicity tests such as long-term inhalation studies on the effects of diesel exhaust]

To determine the chronic toxicity of diesel exhaust, 2,150 F 344 rats were made to inhale various dilutions of exhaust under specific pathogen-free conditions for 16 hours a day, 6 days a week, for 30 months. Ten experimental groups, each with 120 male and 95 female 5 week-old rats, were set up and 14 males and 9 females were usually sacrificed for measurement of the 51 hematological and clinico-biochemical parameters at 7, 13, 19, and 25 months of age, respectively. These parameters were also examined in all surviving rats after 30 months of exhaust inhalation. In this experiment, no remarkable change in any of the parameters was observed in the periodic examinations. Therefore, tendencies of change in parameters were examined by comparing histograms for control and experimental groups. For the reference histograms, we used the values obtained from 144 males and 116 females aged 13-31 months. The first histogram was based on data from 1,352 rats, and the range from the minimum to the maximum value was divided into eight parts. When almost all the values were centered on a peak in the first histogram, this peak was divided into a further eight parts in the second histogram. Histogram evaluation clarified the differences between the control and experimental groups better than general statistical methods such as Student's t-test.     

Increase of paradoxical sleep, induced by injection of ibotenic acid in the ventrolateral posterior hypothalamus in the cat

The intratissular injection of ibotenic acid into the ventrolateral part of the posterior hypothalamus induced a dramatic biphasic and transient hypersomnia immediately after disappearance of the anaesthesia (14 to 24 hrs. after injection). The duration of hypersomnia was related to the dose of neurotoxin injected. Its first period was characterized by an increase in paradoxical sleep (PS) (300%). Then, during the second phase, PS disappeared and there was a subsequent increase of slow wave sleep (SWS) (60%). Finally, on the third day, all cats recovered control level of PS and SWS.     

Improved pulse transit time estimation by system identification analysis of proximal and distal arterial waveforms

We investigated the system identification approach for potentially improved estimation of pulse transit time (PTT), a popular arterial stiffness marker. In this approach, proximal and distal arterial waveforms are measured and respectively regarded as the input and output of a system. Next, the system impulse response is identified from all samples of the measured input and output. Finally, the time delay of the impulse response is detected as the PTT estimate. Unlike conventional foot-to-foot detection techniques, this approach is designed to provide an artifact robust estimate of the true PTT in the absence of wave reflection. The approach is also applicable to arbitrary types of arterial waveforms. We specifically applied a parametric system identification technique to noninvasive impedance cardiography (ICG) and peripheral arterial blood pressure waveforms from 15 humans subjected to lower-body negative pressure. We assessed the technique through the correlation coefficient (r) between its 1/PTT estimates and measured diastolic pressure (DP) per subject and the root mean squared error (RMSE) of the DP predicted from these estimates and measured DP. The technique achieved average r and RMSE values of 0.81 ± 0.16 and 4.3 ± 1.3 mmHg. For comparison, the corresponding values were 0.59 ± 0.37 (P < 0.05) and 5.9 ± 2.5 (P < 0.01) mmHg for the conventional technique applied to the same waveforms and 0.28 ± 0.40 (P < 0.001) and 7.2 ± 1.8 (P < 0.001) mmHg for the conventional technique with the ECG waveform substituted for the ICG waveform. These results demonstrate, perhaps for the first time, that the system identification approach can indeed improve PTT estimation.     

氯胺酮复合咪达唑仑全麻在无水乙醇治疗先天性周围血管畸形中的效果评价

目的:观察氯胺酮复合咪达唑仑在无水乙醇治疗儿童先天性周围血管畸形的应用效果。方法:选择择期全麻下行无水乙醇治疗周围血管畸形儿童50例,随机分为两组:氯胺酮复合咪达唑仑组(M组)和丙泊酚持续输注组(P组),M组以咪达唑仑和氯胺酮基础下全麻,P组采用芬太尼镇痛基础下丙泊酚持续静注全麻,观察并记录入室(T_0)、麻醉诱导后5 min(T_1)、手术开始后30、60、90 min(分别为T_2、T_3、T_4)、拔管后5 min(T_5)的MAP与HR,监测脑电双频指数(bispectral index,BIS)并记录BIS40次数、平均注射无水乙醇量、术中输液量、苏醒时间及苏醒后5 min视觉模拟评分(Visual analog scales,VAS)、Ramsay镇静评分结果。结果:(1)与M组相比,P组MAP(T_2～T_54个时间点)、HR(T_1～T_55个时间点)和BIS值(T_3和T_42个时间点)均显著降低,差异有统计学意义(P0.05);三个指标其余时间点两组患儿相比,差异均无统计学意义(P0.05);(2)与M组患儿相比,P组BIS值40的患儿例数以及应用阿托品和麻黄碱例数均显著增加,差异具有统计学差异(P0.05);两组患儿平均无水乙醇注射量比较显著差异无统计学意义(P0.05);(3)与M组相比,P组患儿全麻苏醒拔管后5 min VAS评分显著降低,Ramsay评分显著升高(P0.05);两组患儿不良事件发生率均无统计学差异(P0.05)。结论:氯胺酮复合咪达唑仑下全麻应用于无水乙醇注射治疗儿童周围血管畸形,能维持术中血流动力学平稳,且缩短苏醒时间。     

Anaesthetic effects of various ratios of ketamine and xylazine in rhesus monkeys (Macacca mulatta).

Intramuscular injection of selected ratios of ketamine and xylazine provided smooth anaesthetic induction, a wide safety margin, and no significant undersirable side effects. Induction and recovery times, duration of anaesthesia, and thermoregulatory ability can be affected by different combinations of ketamine and xylazine. The addition of xylazine to ketamine increases muscle relaxation, recovery time, and duration of anaesthesia, while generally decreasing induction time and thermoregulatory ability.