Hemodynamic physiology and thermoregulation in liposuction

Little is known about the physiology of large-volume liposuction. Patients are exposed to prolonged procedures, general anesthesia, fluid shifts, and infusion of high doses of epinephrine and lidocaine. Consequently, the authors examined the thermoregulatory and cardiovascular responses to liposuction by assessing multiple physiologic factors. The aims of their study were to serially determine hemodynamic parameters perioperatively, to quantify perioperative and postoperative plasma epinephrine levels, and to chronologically document fluctuations in core body temperature. Five female volunteers with American Society of Anesthesiologists' physical status I and II underwent moderate- to large-volume liposuction. Heart rate, blood pressure, mean pulmonary arterial pressure, cardiac index, and central venous pressure were monitored. Serum epinephrine levels and core body temperature were assessed perioperatively. The hemodynamic responses to liposuction were characterized by an increase in cardiac index (57 percent), heart rate (47 percent), and mean pulmonary arterial pressure (44 percent) (p < 0.05). Central venous pressure was not significantly altered. Maximum epinephrine levels were observed 5 to 6 hours after induction. Significant correlations between cardiac index and epinephrine concentrations were shown intraoperatively (r = 0.75). All patients developed intraoperative low body temperatures (mean 35.5 degrees C). An overall enhanced cardiac function was observed in patients subsequent to large-volume liposuction. The etiology of the altered cardiac parameters was multifactorial but may have been attributable in part to the administration of epinephrine, which counters the effects of general anesthesia and operative hypothermia. Additional explanations for raised cardiac output may be hemodilution or emergence from general anesthesia. Elevated mean pulmonary arterial pressure may be a result of subclinical fat embolism demonstrated in previous porcine studies, although fat was not observed in urine. The unchanged central venous pressure levels indicate that young healthy patients with compliant right ventricles can accommodate the fluid loads of large-volume liposuction. Overall hemodynamic parameters remained within safe limits. Within these surgical parameters, patients should be clinically screened for cardiovascular and blood pressure disorders before liposuction is undertaken, and preventative measures should be taken to limit intraoperative hypothermia.     

Body mass index: risk predictor for cosmetic day surgery

Body mass index (BMI; weight per unit surface area) is the scientific yardstick by which overweight is gauged relative to the population norm. The contrary association between obesity and diabetes or hypertension is only too well known. Less appreciated is the heightened sensitivity to respiratory depressants such as sedatives and analgesics in the obese (BMI >/= 30) and the increased incidence of sleep apnea in the morbidly obese (BMI >/= 35)-either or both of which raise the risk of cosmetic surgery when sedation or anesthesia is contemplated. Guided by the BMI, a gender-independent measure of fatness, the surgeon now can inform the patient of her or his relative operative risk and offer an objective rationale for advising overnight hospitalization rather than office-based day surgery.The BMI is readily calculated when height and weight are expressed in metric units, much less so when measured in foot-pound units. In fact, the calculations are sufficiently cumbersome that the BMI remains underused in U.S. office surgery. The author's complimentary "BMI Calculator"-an Excel workbook available on-line to society members-is designed so that office staff need enter only height (in feet and inches) and weight (in pounds) to print the BMI for the patient's permanent record.The BMI places patient weight relative to height in proper perspective for aesthetic surgery, whether with sedation or under general anesthesia. The BMI ought to be as routine a part of the preoperative assessment as blood pressure or hemoglobin content.     

Optimization of conscious sedation in plastic surgery.

The administration of conscious sedation by the plastic surgeon must be safe, efficient, and consistent. In the proper setting, with trained staff and appropriate backup, conscious sedation can allow optimal patient satisfaction with expedient recovery in addition to cost containment. The highly effective local anesthesia afforded by dilute, high-volume ("tumescent") infiltration extends the use of conscious sedation to cases previously performed under general anesthesia or deep sedation. The purpose of this analysis was to identify variables in conscious sedation that affect traditional outcome parameters in ambulatory surgery, particularly the duration of recovery and adverse events such as nausea and emesis. All perioperative and operative records of 300 consecutive patients having plastic surgical procedures under conscious sedation were carefully reviewed. Patients were ASA class I or II by requisite. Conscious sedation followed a standardized administration protocol, using incremental doses of two agents: midazolam (0.25 to 1 mg) and fentanyl (12.5 to 50 mcg). A subset of patients received preoperative oral sedation. Multivariate statistical analysis was conducted using SPSS 8.0 for Windows (SPSS Inc., Chicago, Ill.). Of the 300 patients, same-day discharge was intended for 281. Eight procedure categories were defined. No anesthetic complications occurred. As expected, recovery time was significantly correlated with the duration and type of procedure (p < 0.001) and the total dosage of both intraoperative sedative agents (p < 0.001). Interestingly, a negative correlation with advancing age existed (p < 0.001), likely reflecting the significantly higher intraoperative sedative dosing in younger patients (p < 0.001). When controlled for the effects of procedure duration and intraoperative sedative dosing, two other variables-use of preoperative oral sedation and postoperative nausea/emesis-significantly lengthened recovery time (p = 0.0001 for each). Fifteen unintended admissions occurred secondary to nausea, prolonged drowsiness, or pain control needs. Conscious sedation is an effective anesthetic choice for routine plastic surgical procedures, many of which would commonly be performed under general anesthesia. In our experience with a carefully structured and controlled conscious sedation protocol, the technique has proven to be safe and effective. This analysis of outcome parameters identified two important and potentially avoidable causes of recovery delay following conscious sedation-oral premedication and nausea/emesis. Nausea and emesis were particularly problematic in that they were responsible for 11 of 15 (73 percent) unintended admissions. Preoperative sedation is valuable in certain circumstances, and its use is not discouraged; however, its benefits must be weighed against its unwanted effects, which can include a prolongation of recovery.     

Managing intentions: the end-of-life administration of analgesics and sedatives, and the possibility of slow euthanasia

There has been much debate regarding the 'double-effect' of sedatives and analgesics administered at the end-of-life, and the possibility that health professionals using these drugs are performing 'slow euthanasia.' On the one hand analgesics and sedatives can do much to relieve suffering in the terminally ill. On the other hand, they can hasten death. According to a standard view, the administration of analgesics and sedatives amounts to euthanasia when the drugs are given with an intention to hasten death. In this paper we report a small qualitative study based on interviews with 8 Australian general physicians regarding their understanding of intention in the context of questions about voluntary euthanasia, assisted suicide and particularly the use of analgesic and sedative infusions (including the possibility of voluntary or non-voluntary 'slow euthanasia'). We found a striking ambiguity and uncertainty regarding intentions amongst doctors interviewed. Some were explicit in describing a 'grey' area between palliation and euthanasia, or a continuum between the two. Not one of the respondents was consistent in distinguishing between a foreseen death and an intended death. A major theme was that 'slow euthanasia' may be more psychologically acceptable to doctors than active voluntary euthanasia by bolus injection, partly because the former would usually only result in a small loss of 'time' for patients already very close to death, but also because of the desirable ambiguities surrounding causation and intention when an infusion of analgesics and sedatives is used. The empirical and philosophical implications of these findings are discussed.     

右美托咪定在临床麻醉中的应用进展

右美托咪定(Dexmedetomidine,Dex)是一种高度选择性α2肾上腺素受体激动剂,自1999年被FDA批准作为一种短期的镇静-镇痛药在重症监护室使用以来,Dex广泛应用于整个围术期的镇静和镇痛,即可作为术前用药,又可作为一种兼用于一般性和区域性的麻醉药,或是作为术后镇静和镇痛药。目前研究表明,Dex是许多临床应用的一种有效药物,该药已在减少阿片样药物、苯二酚和异丙酚的需求中显示出其功效。在广泛的临床条件中,Dex即被认为是一种有效的、安全的辅药,又已成为一种有效的治疗剂,其在临床麻醉应用中具有广泛的前景。本文从Dex的作用机制、围术期使用、术后使用、ICU镇静、清醒光纤插管、心脏外科手术及肥胖患者外科手术中应用等方面对其在临床麻醉中的应用现状作一综述,为Dex的临床应用及基础研究提供理论依据。     

快通道麻醉在小儿先天性心脏病手术中的应用及对镇静、镇痛效果的影响

目的:探讨快通道麻醉在小儿先天性心脏病手术中的应用及对镇静、镇痛效果的影响。方法:选择2016年6月至2018年5月在桂林医学院附属医院进行手术治疗的小儿先天性心脏病患儿82例,按照随机数字表法分为对照组(41例)和观察组(41例),对照组进行常规麻醉,观察组则采用快通道麻醉。对比两组患儿麻醉药物用量、手术时间、阻断时间、体外循环时间、术后拔管时间、住院时间、住院费用及并发症发生情况,观察两组患儿术后12h镇静、镇痛效果。结果:观察组患儿芬太尼和罗库溴铵用量明显低于对照组(P0.05)。两组患儿的术中各指标比较无统计学差异(P0.05),而与对照组相比,观察组患儿术后住院时间、拔管时间均缩短,且住院费用减少(P0.05)。观察组患儿术后12h的镇静及镇痛效果均优于对照组(P0.05)。观察组患儿术后并发症发生率为17.07%(7/41),低于对照组的39.02%(16/41)(P0.05)。结论:快通道麻醉可减少小儿先天性心脏病手术的芬太尼和罗库溴铵用量,不仅缩短术后拔管时间和住院时间,降低住院费用,而且可改善镇静及镇痛效果,安全有效。     

Comparison of Neurologic Responses to the Use of Medetomidine as a Sole Agent or Preanesthetic in Laboratory Beagles

Different dose regimens of medetomidine (a potent α2-adrenergic agonist), adding up to a combined dose of 80 µg/kg, were administered to laboratory beagles to determine physiologic responses including neurologic. The study was intended to determine EEG responses where sufficient sedative and analgesic effects are reached with medetomidine and in contrast its effects when used with ketamine or halothane. Cardiopulmonary responses were very similar in each dose regimen, showing the characteristic properties of single doses of 80 µg/kg of medetomidine. Effective sedative and analgesic duration seemed to be a function of when the largest dose was administered. Adequate additional sedative and analgesic could be gained from injections at doses of half of the initial one. The potent sedative and analgesic effects of medetomidine confirmed by neurologic evaluation supports its potential use as a premedication to general anesthesia in dogs. In this study, 2 different doses of medetomidine were also tested as premedication to both ketamine HCl and halothane anesthesia. Neorologic responses were determined at the same time cardiopulmonary parameters, anesthetic quality, and dose requirements were recorded. Medetomidine was found to have favorable qualities in conjunction with these anesthetics. Cardiopulmonary parameters remained satisfactory in both groups as preanesthetic medication prior to halothane, but no additional benefits could be seen from doses of 40 µg/kg medetomidine compared to 20 µg/kg, except a significant 30% reduction in halothane requirement. The positive chronotropic and inotropic properties of ketamine restored the medeto-midine-induced bradycardia and produced a short anesthetic period of 15 to 30 min depending on the dose of medetomidine. The quality of anesthesia was better when 40 µg/kg medetomidine was used, but recorvery was quicker with 20 µg/kg medetomidine. Medetomidine significantly reduced cerebral activity as demonstrated by recordings of total amplitude and frequency evaluation of the EEG with compressed spectral analysis. This analytical method was effective in confirming clinical signs of sedation, analgesia, and anesthesia in canine subjects.     

Low-dose propofol infusion for sedation during local anesthesia

The safety and efficacy of lose-dose propofol for sedation were investigated on 90 consenting patients who had undergone surgical procedures with local anesthesia. After being premedicated with intravenous midazolam 0.05 mg.kg(-1), all patients were randomly divided into two groups and received intravenously either a loading dose of propofol 0.8 mg.kg(-1) followed by a continuous infusion of propofol 30 microg.kg(-1)min(-1) (propofol group) or an equivalent volume of saline (placebo group) during operation. Study groups were compared with respect to the level of sedation, hemodynamic variables, oxygen saturation, and the incidence of intraoperative side effects. In addition, the discharge time and the satisfaction of both patients and surgeons with this sedative technique were assessed. Propofol reduced patients' discomfort and lowered their arterial pressure and heart rate during the infiltration of local anesthetics. It also promoted an adequate level of sedation without clinically significant oxygen desaturation in the intraoperative period. Surgeons and patients in the propofol group showed a higher level of satisfaction than those in the placebo group. There was no significant difference between the two groups with regard to the incidence of adverse effects and the discharge time. In conclusion, it was found that the use of low-dose propofol infusion was a safe and effective sedative technique for local anesthesia.     

利多卡因经气管内给药和静脉给药对全麻苏醒期患者镇静镇痛效果、血流动力学和呛咳反应的影响

摘要 目的：探讨利多卡因经气管内给药和静脉给药对全麻苏醒期患者镇静镇痛效果、血流动力学和呛咳反应的影响。方法：选取2018年3月~2019年8月于我院在气管内全麻下完成泌尿外科、腹部外科并预计于术后可以迅速拔除气管导管的患者63例,上述患者根据随机数字表法分为A组（n=31）和B组（n=32）,A组患者给予利多卡因静脉给药,B组患者给予利多卡因经气管内给药,比较两组患者苏醒时间、拔管时间、镇静镇痛效果、血流动力学及呛咳反应。结果：两组苏醒时间、拔管时间组间比较差异无统计学意义（P>0.05）。两组插管时、拔管时、拔管后10 min心率（HR）、收缩压（SBP）、舒张压（DBP）均呈先升高后降低趋势,且B组插管时、拔管时、拔管后10 min的HR、SBP、DBP均低于A组（P<0.05）。两组拔管时、拔管后10 min组内及组间镇静-躁动评分(SAS)比较差异无统计学意义（P>0.05）;两组拔管后10 min疼痛视觉模拟量表(VAS)评分高于拔管时,但B组低于A组（P<0.05）。B组患者插管时、拔管时呛咳反应发生率均低于A组（P<0.05）。结论：与静脉给药相比,全麻苏醒期患者给予利多卡因经气管内给药,镇静镇痛效果确切,可减轻血流波动,降低插管时、拔管时呛咳反应发生率。     

Pharmacokinetics and safety of lidocaine and monoethylglycinexylidide in liposuction: a microdialysis study

High doses of lidocaine are administered to patients undergoing liposuction. Monoethylglycinexylidide, the active metabolite of lidocaine, is 80 to 90 percent as potent as lidocaine, and its relative toxicity is approximately that of lidocaine. Monoethylglycinexylidide has not previously been measured in studies on lidocaine in liposuction. The aims of this study were to characterize systemic exposure to lidocaine and monoethylglycinexylidide and to measure lidocaine and monoethylglycinexylidide levels within the tissues. Five female volunteers between the ages of 29 and 40 years underwent liposuction. Lidocaine (1577 to 2143 mg, corresponding to 19.9 to 27.6 mg/kg) was infiltrated during the procedure. Levels of lidocaine and monoethylglycinexylidide in blood and lipoaspirate were assessed perioperatively. Tissue lidocaine and monoethylglycinexylidide levels were measured postoperatively using a microdialysis technique in vivo. The peak (maximal) concentration of lidocaine plus monoethylglycinexylidide was 2.2 to 2.7 microg/ml. Time to peak lidocaine plus monoethylglycinexylidide was 8 to 28 hours after infiltration began. Absorbed lidocaine was estimated to be 911 to 1596 mg; therefore, 45 to 93 percent (mean, 64 percent) of the infiltrated dose was ultimately absorbed. Lipoaspirate analysis showed that 9.1 to 10.8 percent (mean, 9.7 percent) of the infiltrated dose was removed during the procedure. Tissue lidocaine levels below 5 microg/ml were demonstrated from 4 to 8 hours postoperatively. The peak lidocaine plus monoethylglycinexylidide concentration was within safe limits in this group of subjects. Time to peak lidocaine plus monoethylglycinexylidide signifies a delayed peak and therefore a longer period of potential lidocaine toxicity than was originally thought. Microdialysis results demonstrated that tissue lidocaine levels may be subtherapeutic within 4 to 8 hours of the procedure. Investigation into factors controlling the resorption of lidocaine during liposuction is warranted in an effort to improve the duration of effect. Furthermore, considering the active metabolite monoethylglycinexylidide, longitudinal studies are necessary to determine whether improving the side effect profile of lidocaine by reducing the dose administered during liposuction may be possible without decreasing the perioperative analgesic effect.     

An outcome study comparing intravenous sedation with midazolam/fentanyl (conscious sedation) versus propofol infusion (deep sedation) for aesthetic surgery

The purpose of this study was to determine the differences in measurable outcomes following aesthetic procedures performed under intravenous sedation with incremental doses of midazolam and fentanyl and those performed under propofol infusion. The authors' hypothesis was that the differences in these outcome parameters are not significant between these intravenous sedation protocols. All intraoperative and perioperative records of 84 consecutive patients having aesthetic surgery under a conscious sedation protocol using incremental doses of intravenous midazolam and fentanyl were retrospectively reviewed and compared with the records of a second group of 85 patients having aesthetic surgery under a deep sedation regimen based primarily on propofol infusion. All procedures were hospital based and performed by two surgeons. Twenty-eight different parameters were examined by chart review. In addition, a patient questionnaire was used to assess patient satisfaction and patient recall of operative and perioperative pain, anxiety, nausea, and vomiting. Multivariate statistical analysis was conducted. The two sedation groups were similar with regard to aesthetic procedures performed and patient demographics. The mean duration of operative time was statistically equivalent (152 minutes and 153 minutes). In both groups, there were minor adverse intraoperative events reported but no significant complications. Transient hypotension was more common in the propofol infusion group (12.9 percent versus 2.4 percent, p = 0.018), but no patient required intervention beyond reducing the sedative agent or increasing intravenous fluids. The amount of supplemental fentanyl given intraoperatively was significantly higher in the group whose primary agent for sedation was propofol infusion than the group who received midazolam/fentanyl (209 mug and 143 mug, respectively). The overall questionnaire response rate was 80 percent for both groups. The midazolam/fentanyl sedation group had more recall of "unpleasant intraoperative events" (17 percent versus 3 percent, p = 0.007). However, both groups had low recall of intraoperative pain, anxiety, and nausea. The propofol infusion group experienced significantly more nausea in the recovery room (p = 0.002), nausea at the time of discharge (p = 0.009), and nausea the evening after the operation (p = 0.013). Greater than 90 percent of the patients in both groups would have the same anesthetic in the future rather than undergo general anesthesia. Patient safety, outcomes, and satisfaction are similar in plastic surgery procedures performed under sedation protocols using either incremental doses of midazolam and fentanyl or propofol infusion. All operative and postoperative outcomes for pain, anxiety, and vomiting were similar in the two groups except for immediate postoperative nausea, which was higher in the propofol infusion group. The overall satisfaction of patients undergoing plastic surgery procedures under these intravenous sedation protocols appears very high.     

右美托咪定和丙泊酚对髋部骨折手术患者术后镇静效果及谵妄的影响

目的:探讨右美托咪定和丙泊酚对髋部骨折手术患者术后镇静效果及谵妄改善效果的影响。方法:选取2016年4月-2018年3月于我院行髋部骨折手术的108例患者作为研究对象,按随机数字表法分为观察组(n=54)和对照组(n=54),两组患者术中均采用全身静脉麻醉,观察组患者给予右美托咪定进行镇静诱导,对照组患者给予丙泊酚进行镇静诱导。术后24h,采用Ramsay镇静评分评价两组患者术后的镇静效果,采用视觉模拟量表(VAS)评分评价术后镇痛效果,术后1周,对两组患者术后谵妄发生率、谵妄评定量表(CAM)评分、简易智能精神状态检查量表(MMSE)评分进行比较,记录不良反应发生情况。结果:术后24h,观察组患者的Ramsay镇静评分高于对照组,VAS评分及镇痛药追加量低于对照组,差异有统计学意义(P0.05)。术后1周,观察组患者谵妄发生率、CAM评分低于对照组,MMSE评分高于对照组,差异有统计意义(P0.05)。观察组不良反应发生率为9.26%,与对照组的14.81%比较,差异无统计学意义(P0.05)。结论:与丙泊酚相比,髋部骨折手术患者应用右美托咪定可获得更好的术后镇静、镇痛效果,能够降低谵妄的发生率,且无严重不良反应发生,有较高的临床应用价值。     

Incidence of Inadvertent Intraoperative Hypothermia and Its Risk Factors in Patients Undergoing General Anesthesia in Beijing: A Prospective Regional Survey

Background/Objective

Inadvertent intraoperative hypothermia (core temperature <36⁰ C) is a recognized risk in surgery and has adverse consequences. However, no data about this complication in China are available. Our study aimed to determine the incidence of inadvertent intraoperative hypothermia and its associated risk factors in a sample of Chinese patients.

Methods

We conducted a regional cross-sectional survey in Beijing from August through December, 2013. Eight hundred thirty patients who underwent various operations under general anesthesia were randomly selected from 24 hospitals through a multistage probability sampling. Multivariate logistic regression analyses were applied to explore the risk factors of developing hypothermia.

Results

The overall incidence of intraoperative hypothermia was high, 39.9%. All patients were warmed passively with surgical sheets or cotton blankets, whereas only 10.7% of patients received active warming with space heaters or electric blankets. Pre-warmed intravenous fluid were administered to 16.9% of patients, and 34.6% of patients had irrigation of wounds with pre-warmed fluid. Active warming (OR = 0.46, 95% CI 0.26–0.81), overweight or obesity (OR = 0.39, 95% CI 0.28–0.56), high baseline core temperature before anesthesia (OR = 0.08, 95% CI 0.04–0.13), and high ambient temperature (OR = 0.89, 95% CI 0.79–0.98) were significant protective factors for hypothermia. In contrast, major-plus operations (OR = 2.00, 95% CI 1.32–3.04), duration of anesthesia (1–2 h) (OR = 3.23, 95% CI 2.19–4.78) and >2 h (OR = 3.44, 95% CI 1.90–6.22,), and intravenous un-warmed fluid (OR = 2.45, 95% CI 1.45–4.12) significantly increased the risk of hypothermia.

Conclusions

The incidence of inadvertent intraoperative hypothermia in Beijing is high, and the rate of active warming of patients during operation is low. Concern for the development of intraoperative hypothermia should be especially high in patients undergoing major operations, requiring long periods of anesthesia, and receiving un-warmed intravenous fluids.     

Anesthesia for outpatient female sterilization

This issue of the Bulletin deals with the principles of anesthesia for outpatient female sterilization with emphasis on techniques for laparoscopy and minilaparotomy. General anesthesia techniques provide analgesia, amnesia, and muscle relaxation and are particularly useful for managing the anxious patient. Disadvantages include increased expense, need for specialized equipment, and highly trained personnel, and delayed recovery. Complications, though relatively rare, can be life-threatening and include aspiration of stomach contents, hypoxia, hypercarbia, hypotension, hypertension, cardiac arrhythmias, cardiorespiratory arrest, and death. There is no single preferred technique of general anesthesia, athough most anesthetists employ methods that allow rapid recovery of faculties, enabling the patient to be discharged soon after surgery. To accomplish this end, light anesthesia with sodium thiopental induction and nitrous oxide maintenance is often used. Short duration muscle relaxation with an agent such as succinylcholine supplements this technique. Other techniques include light anesthesia with inhalational anesthetic agents and the use of intravenous ketamine. Local anesthesia augmented by systemic and/or inhalational analgesia is supplanting general anesthesia techniques for laparoscopy in many locales. This approach is also particularly well-suited for minilaparotomy in developing countries, where it has achieved its greatest popularity. The local technique carries with it reduced morbidity and mortality but may not entirely relieve discomfort. The primary danger of local anesthesia is respiratory depression due to excessive narcosis and sedation. The operator must be alert to the action of the drugs and should always use the minimal effective dose. Although toxicity due to overdosage with local anesthetic drugs is occasionally experienced, allergic reactions to the amide-linkage drugs such as lidocaine or bupivacaine are exceedingly rare. For outpatient laparoscopy or minilaparotomy, local anesthesia with proper preoperative counselling and premedication should provide adequate relief of pain and is the method of choice, unless the patient cannot be examined awake or is totally uncooperative. The decision to utilize either general or local anesthesia should be made by the patient after thorough counselling by the surgical team. In many cases, the circumstances of the surgical environment will dictate the choice, but patient comfort and safety should always be the goal.     

Azaperone and azaperone-ketamine as a neuroleptic sedative and anesthetic in rats and mice

Azaperone alone and combined with ketamine were evaluated as sedative and anesthetic agents in outbred rats and mice. Using azaperone alone the duration of immobility was 1.9 to 10.8 hours for mice and 0.9 to 2.4 hours for rats. The withdrawal reflex was not eliminated from mice receiving azaperone alone; however, the withdrawal reflex was eliminated from 0.9 to 2.4 hours in rats receiving azaperone. Azaperone produced a tachypnea in rats and male mice while a depressed respiratory rate was observed in female mice. Using azaperone combined with ketamine, the duration of immobilization was 1.1 to 8.8 hours for mice and 1.3 to 6.0 hours for rats. The duration loss of the withdrawal reflex, which was used as an indication of surgical anesthesia, was 0.9 to 1.8 hours for mice and 1.0 to 6.0 hours for rats. An increase in respiratory rate was observed in rats given the combination while mice given the combination showed transient tachypnea followed by bradypnea. Overall, azaperone alone was shown to provide sedation in mice as compared to a dose dependent anesthesia in rats. The azaperone-ketamine combination produced a surgical plane of anesthesia in both rats and mice. Azaperone and the azaperone-ketamine combination appear to be a suitable alternative to sedatives and anesthetics currently used in rats and mice.     

The effect of various centrally active drugs on adenosine uptake by the central nervous system

1. Adenosine and its analogs depress the firing of neurons in various brain regions. The primary mode of action of adenosine in exerting this effect appears to be the depression of transmitter release from presynaptic nerve terminals. This is a result of reduced calcium mobilization. 2. Adenosine uptake inhibitors and deaminase inhibitors depress the firing of central neurons. Adenosine antagonists, caffeine and theophylline, excite central neurons. Adenosine is therefore likely to be released in sufficient quantities to exert an ongoing modulation of synaptic transmission in the intact brain. 3. A number of groups of centrally active drugs inhibit adenosine uptake by brain synaptosomal preparations. These include the benzodiazepines, phenothiazines, various other sedatives and hypnotics, tricyclic antidepressants, non-steroidal anti-inflammatory analgesics, some steroids, diphenylhydantoin, puromycin and toyocamycin. 4. It is proposed that many agents with anxiolytic, sedative, analgesic or anti-convulsant actions may achieve their effects by inhibiting adenosine uptake and thus potentiating extracellular adenosine levels. 5. Morphine also elevates extracellular adenosine levels but achieves this by enhancing adenosine release.     

Postoperative pain management in patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis: a narrative review

Posterior spinal fusion for adolescent idiopathic scoliosis is one of the most invasive surgical procedures performed in children and adolescents. Because of the extensive surgical incision and massive tissue trauma, posterior spinal fusion causes severe postoperative pain. Intravenous patient-controlled analgesia with opioids has been the mainstay of postoperative pain management in these patients. However, the use of systemic opioids is sometimes limited by opioid-related side effects, resulting in poor analgesia. To improve pain management while reducing opioid consumption and opioid-related complications, concurrent use of analgesics and analgesic modalities with different mechanisms of action seems to be rational. The efficacy of intrathecal opioids and nonsteroidal anti-inflammatory drugs as components of multimodal analgesia in scoliosis surgery has been well established. However, there is either controversy or insufficient evidence regarding the use of other analgesic methods, such as continuous ketamine infusion, perioperative oral gabapentin, acetaminophen, continuous wound infiltration of local anesthetics, a single dose of systemic dexamethasone, and lidocaine infusion in this patient population. Moreover, appropriate combinations of analgesics have not been established. The aim of this literature review is to provide detailed information of each analgesic technique so that clinicians can make appropriate choices regarding pain management in patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion.     

Fatal outcomes from liposuction: census survey of cosmetic surgeons

Troubling reports of adverse outcomes after liposuction prompted a census survey of aesthetic plastic surgeons. All 1200 actively practicing North American board-certified ASAPS members were polled by facsimile, then mail, regarding deaths after liposuction. Patient initials together with case summaries precluded data replication yet assured patient anonymity and preserved surgeon privacy. Incomplete returns or ambiguous findings were authenticated, where feasible, by direct follow-up. Total number of lipoplasties performed by plastic surgeons was interpolated from the ASPRS procedure database for the survey time frame of 1994 to mid-1998. Lacking reliable annual case volume estimates, deaths from lipoplasties performed by non-ABPS surgeons were excluded from the actual mortality rate computation but were included in cause-of-death ranking statistics. Responding aesthetic plastic surgeons (917 of 1200) reported 95 uniquely authenticated fatalities in 496,245 lipoplasties. In this census survey, the mortality rate computed to 1 in 5224, or 19.1 per 100,000. A virtually identical 20.3 per 100,000 mortality rate was obtained in a 1997 random survey commissioned by the parent society. Pulmonary thromboembolism remains as the major killer (23.4+/-2.6 percent); lacking consistent medical examiners' toxicology data, the putative role of high-dose lidocaine cardiotoxicity could not be ascertained. Where so stated, many deaths occurred during the first night after discharge home; prudence suggests vigilant observation for residual "hangover" from sedative/anesthetic drugs after lengthy procedures. Taken together, these two independent surveys peg the late 1990s mortality rate from liposuction at about 20 per 100,000, or 1 in every 5000 procedures. Set beside the 16.4 per 100,000 fatality rates of U.S. motor vehicle accidents, liposuction is not an altogether benign procedure. We do not have comparable mortality data for lipoplasties performed by non-ABPS-certified physicians.     

Acute physiological responses to castration-related pain in piglets: the effect of two local anesthetics with or without meloxicam

Methods to reduce castration-related pain in piglets are still issues of concern and interest for authorities and producers. Our objectives were to estimate the effectiveness of two protocols of local anesthesia (lidocaine and the combination of lidocaine+bupivacaine) as well as the use of meloxicam as a postoperative analgesic in alleviating castration-related pain, measured by acute physiological responses. Eight groups (15 piglets/group) were included in the study: (1) castration without anesthesia or analgesia, without meloxicam (TRAD WITHOUT), (2) castration without anesthesia or analgesia, but with meloxicam (TRAD WITH), (3) handling without meloxicam (SHAM WITHOUT), (4) handling with meloxicam (SHAM WITH), (5) castration after local anesthesia with lidocaine but without meloxicam (LIDO WITHOUT), (6) castration after local anesthesia with lidocaine and meloxicam (LIDO WITH), (7) castration after local anesthesia with lidocaine+bupivacaine without meloxicam (LIDO+BUPI WITHOUT), (8) castration after local anesthesia with lidocaine+bupivacaine and meloxicam (LIDO+BUPI WITH). Acute physiological responses measured included skin surface temperature and serum glucose and cortisol concentrations. On days 4 and 11 post-castration BW was recorded and average daily gain was calculated over this period. Furthermore, piglet mortality was recorded over the 11-day post-castration period. Administration of local anesthetic or meloxicam did not prevent the decrease in skin surface temperature associated with castration. Lidocaine reduced the increase in glucose concentration associated with castration. For castrated pigs, the joint use of lidocaine and meloxicam caused a significant decrease in cortisol concentration; the combination of intratesticular lidocaine and bupivacaine did not seem to be more effective than lidocaine alone. No effect of treatments on mortality and growth were detected.     

HEADACHE—Pharmacological Approach to Treatment

The great majority of headaches a physician treats in office practice can be divided into two main categories, muscular contraction headache of tension type and vascular headaches of the migraine type.The most satisfactory symptomatic therapy for tension headache is by the use of a nonnarcotic analgesic agent combined with a tranquilizer or sedative. On the other hand, symptomatic relief of migraine is best obtained by the use of a suppository of ergotamine tartrate and caffeine combined with an antiemetic or antispasmodic.Interval treatment of patients with tension and migraine headache centers on helping the patient understand his emotional problems. Prophylactic drug therapy for patients with tension headache includes the limited use of tranquilizers and sedatives. Recently, striking benefits in some patients with migraine have been achieved by the prophylactic use of the antiserotonin drug methysergide (UML 491).