Evaluation of the oesophageal-tracheal double-lumen tube (Combitube) during general anaesthesia

OBJECTIVES: Evaluation of safety and effectiveness of the Combitube during general anaesthesia. PATIENTS AND METHODS: 250 patients undergoing general anaesthesia were enrolled in the study. The respective types and duration of surgery, ease of insertion of the Combitube, and potential complications were recorded. Maximum ventilatory pressures and leak fraction were also evaluated in this study. RESULTS: Duration of surgery varied between 20 and 410 min. More than 96% of the blind Combitube insertions were successful at the first attempt, with a mean time of less than 18 +/- 5 seconds (range 12-24 seconds). In 99% of patients the Combitube worked well, and adequate oxygenation and ventilation was possible. All patients were haemodynamically stable during the entire duration of surgery. In all patients, pulse oximetry showed an oxygen saturation of 97 +/- 2% and an end-tidal carbon dioxide of 38 +/- 6 mmHg. Leak fraction, calculated as a fraction of the inspired volume, did not increase to more than 5% up to a ventilation pressure of 40 cm H2O. Superficial laceration occurred in 18 patients (7.2%) without further sequelae. No severe injuries were observed during the study period. CONCLUSION: Ventilation via the Combitube appears to be safe and effective during general anaesthesia. Practice in elective cases is a requirement for successful use in an emergency situation.     

Comparative evaluation of the bispectral index (BIS) and BISpro during propofol anaesthesia

ObjectiveTo compare the accuracy, correlation and agreement between the bispectral index (BIS) and BISpro during propofol anaesthesia.MethodsThe BIS, BISpro, heart rate, target-concentration of propofol and Observer’s Assessment of Alertness and Sedation (OAA/S) score were recorded every 30 s in female patients scheduled for hysteroscopic surgery. Propofol anaesthesia was induced by an initial target-controlled concentration (1.0 μg/ml) followed by a stepwise increase (0.5 μg/ml) until the patient was unresponsive. Spearman’s correlation coefficient and prediction probability were calculated for the association between sedation levels and the above parameters. The ability of investigated parameters to distinguish between OAA/S scores was analysed. Bland–Altman analysis was used to compare the agreement between BIS and BISpro. The BIS and BISpro cut-off values for lost response were also determined.ResultsOut of 30 patients in total, a high correlation was found between BIS and BISpro, and both correlated well with OAA/S score. Only BIS was able to distinguish all investigated OAA/S states accurately, but the ability to predict OAA/S score 5 to loss of response was comparable between BIS and BISpro. The calculated cut-off values were 68 for BIS and 70 for BISpro.ConclusionBISpro and BIS are reliable monitors of general anaesthesia during sedation.Trial registration number: Chinese Clinical Trial Registry (URL: www.chictr.org.cn): ChiCTR1900024037 (retrospectively registered).     

Implementation of a standards-based anaesthesia record compliant with the health level 7 (HL7) clinical document architecture (CDA)

With the increasing use of anaesthesia information management systems (AIMS) there is the opportunity for different institutions to aggregate and share information both nationally and internationally. Potential uses of such aggregated data include outcomes research, benchmarking and improvement in clinical practice and patient safety. However, these goals can only be achieved if data contained in records from different sources are truly comparable and there is semantic inter-operability. This paper describes the development of a standard terminology for anaesthesia and also a Domain Analysis Model and implementation guide to facilitate a standard representation of AIMS records as extensible markup language documents that are compliant with the Health Level 7 Version 3 clinical document architecture. A representation of vital signs that is compliant with the International Standards Organization 11073 standard is also discussed.     

不同麻醉方式对兔眼心反射牵拉阈值的影响

目的 探讨何种麻醉方式能最大限度的降低牵拉兔内直肌引起眼心反射的牵拉阈值,从而对眼科手术中预防眼心反射的发生给予指导.方法 根据不同的麻醉方式,将40只家兔均分为4组:A组:未干预组;B组:表面麻醉组,C组:球后麻醉组,D组:氯胺酮全身麻醉组.牵拉兔内直肌,以心率下降至基础心率的10%作为发生了眼心反射,记录此时数显拉力计数值为引起兔眼心反射的牵拉阈值.进行统计学分析.结果 牵拉兔内直肌引起眼心反射的牵拉阈值,不同麻醉方式之间有差别(P<0.01).表面麻醉组牵拉阈值高于未干预组,但差异无显著性(P>0.05),球后麻醉组牵拉闭值高于表面麻醉组,差异有显著性(P<0.05),氯胺酮全身麻醉组牵拉阈值高于球后麻醉组,差异有显著性(P<0.05).结论 氯胺酮全身麻醉与球后麻醉及表面麻醉比较,可显著提高牵拉兔内直肌引起眼心反射的牵拉阈值.     

Empirical mode decomposition analysis of HRV data from patients undergoing local anaesthesia (brachial plexus block)

Spectral analysis of heart rate variability (HRV) is used for the assessment of cardiovascular autonomic control. In this study, a data-driven adaptive technique called empirical mode decomposition (EMD) and the associated Hilbert spectrum has been used to evaluate the effect of local anaesthesia on HRV parameters in a group of 14 patients undergoing axillary brachial plexus block. The normalized amplitude Hilbert spectrum was used to calculate the error index associated with the instantaneous frequency. The amplitude and the frequency values were corrected in the region where the error was higher than twice standard deviation. The intrinsic mode function (IMF) components were assigned to the LF and the HF part of the signal by making use of the centre frequency and the standard deviation spectral extension estimated from the marginal spectrum of the IMF components. The optimal range of the stopping criterion was found to be between 4 and 9 for the HRV data. The statistical analysis showed that the LF/HF ratio decreased within an hour of the application of the brachial plexus block compared to the values at the start of the procedure. These changes were observed in 13 of the 14 patients included in this study.     

Local anaesthesia – Part 1: Regional anaesthesia of the head

ABSTRACT:

Regional anaesthesia is one of the most effective ways of providing pain relief to veterinary patients. The equipment list for a significant number of local anaesthesia techniques includes just a syringe, needle, local anaesthetic and appropriate knowledge of anatomy. So why aren't they being used more in veterinary medicine? As veterinary nurses, it is important that we have a good comprehension of the analgesic techniques available, how they work and in which scenarios they can be helpful for our patients. This is part one of three articles examining regional anaesthesia of the head, thoracic limbs and hind limbs.     

Local anaesthesia versus general anaesthesia for cardioverter-defibrillator implantation.

AIMS: Cardioverter-defibrillators are conventionally implanted under general anaesthesia. However, implantation under conscious sedation is being increasingly used. It has been shown that cardioverter-defibrillators can be implanted in a more pacemaker-like approach: under local anaesthesia for the surgical procedure, and with mild sedation for defibrillation threshold testing only. The aim of the present study was to compare local and general anaesthesia in defibrillation threshold testing and implantation of cardioverter-defibrillators. METHODS AND RESULTS: Forty patients were assigned to two groups: in the first 20 consecutive patients the cardioverter-defibrillator was implanted under general anaesthesia (GA), and in the subsequent 20 patients under local anaesthesia (LA). There was no significant difference between the two groups in regard of age, body weight, underlying disease, left ventricular ejection fraction, and NYHA classification. The defibrillation threshold was 13.7 +/- 5.5 J under local anaesthesia versus 10.7 +/- 4.7 J under general anaesthesia (n.s.). For defibrillation threshold testing 7.9 +/- 3.6 shocks had to be applied in patients under general anaesthesia versus 6.2 +/- 1.3 shocks under local anaesthesia (n.s.). Mean heart rate, arterial oxygen saturation and mean arterial blood pressure remained stable throughout defibrillation threshold testing, irrespective of the type of anaesthesia used. The duration of the surgical procedure was 62 +/- 16 min under GA and 60 +/- 14 min under LA (n.s.), however, the entire implantation procedure was significantly longer in patients under general anaesthesia than in those under local anaesthesia (124 +/- 24 min and 97 +/- 22 min, respectively, p < 0.005). There were no complications in either group and the procedure was well tolerated. With the use of local anaesthesia the cost of anaesthesia were reduced by 72%. CONCLUSION: Local anaesthesia in combination with mild sedation is as safe and well tolerated as general anaesthesia in cardioverter-defibrillator implantation. Lidocaine used for local anaesthesia does not adversely affect the defibrillation threshold. Device implantation in a pacemaker-like approach results in a significant reduction in total procedure time and costs, and facilitates scheduling of the procedure.     

Cholinesterase and anaesthesia

There appear to be two genetic loci for cholinesterase, E₁ and E₂. The first allele is closely linked with the transferrin locus and is probably on chromosome number 1. At the second (E₂) locus only one variant has been described. At the E₁ locus at least 4 alleles have been detected: the usual (E₁^u), atypical (E₁^a), fluoride-resistant (E₁^r) and silent (E₁^s) alleles, while the latter is probably composed of 2 subgroups.A few other very rare variants have been described and are listed in Table I.     

氟比洛芬酯对异丙酚-瑞芬太尼全凭静脉麻醉深度的影响

目的评价氟比洛芬酯对异丙酚-瑞芬太尼全凭静脉麻醉患者麻醉深度的影响。方法择期全身麻醉手术患者30例,ASAⅠ～Ⅱ级,麻醉深度采用脑电双频指数(BIS)和听觉诱发电位指数(AAI)监测,静脉注射咪唑安定0.05 mg/kg、异丙酚2 mg/kg、芬太尼3μg/kg、罗库溴铵1 mg/kg,行气管插管。术中异丙酚5 mg.kg-1.h-1、瑞芬太尼0.15μg.kg-1.min-1维持麻醉,维库溴铵间断加入维持肌松。调节麻醉药物输注速率使AAI值维持在20±5,BIS值维持在50±5。待各项麻醉监测指标稳定维持20 min后,静脉注射氟比洛芬酯1 mg/kg,分别记录氟比洛芬酯注射即刻?注射后5 min、10 min、15 min、20 min、30 min的AAI、BIS、平均动脉压(MAP)和心率(HR)值。结果给药后各时点患者的AAI、BIS、MAP和HR值与给药前相比较差异无统计学意义(P>0.05)。结论临床剂量的氟比洛芬酯在异丙酚-瑞芬太尼全凭静脉麻醉中对麻醉深度无明显影响。     

Measuring the performance of audible alarms for anaesthesia

The ergonomic performance of an integrated set of 17 audible alarm sounds, divided into low, medium and high priority classes has been undertaken. The sounds were tested for their ease of learning/recall, and how closely their intrinsic perceived urgency matched to a clinical assessment of urgency. The tests were computer-administered and performed on 21 volunteers aged from 18 to 52, in two sessions a few days apart. Session 1 taught the meanings of the alarm sounds and session 2 measured the performance of the sounds. The mean correct identification rate for the sounds was 48.4% (range 10.3-90.0%) with 97.5% of misidentifications within sound priority class. The urgency correlation was statistically significant (r=0.85, p<0.001) with all priority classes included but within priority class correlations were not statistically significant. Poor within priority class performances were ascribable to a priori aspects of the design of the sound system.     

熵指数监测下观察七氟烷在全麻过程中的应用

目的 研究熵指数指导下七氟烷在全麻过程中的应用，并与丙泊酚比较，初步探讨熵指数与OAA/S评分的相关性。方法 选择40例ASAⅠ或Ⅱ级在全麻下行择期腹腔镜下胆囊切除术的患者。随机分为七氟烷组和丙泊酚组，每组20例，麻醉期间分别采用七氟烷、雷米芬太尼和阿曲库铵或丙泊酚，雷米芬太尼和阿曲库铵维持。采用熵指数监测麻醉深度，将熵指数控制在40～60之间，术毕采用镇静/警觉评分OAA/S反映患者全麻后意识恢复程度，并记录到达不同评分的时间及相应熵值（RE和SE）,同时记录麻醉过程中及术毕清醒时对应的心率(HR)、平均动脉压(MAP)、脉搏血氧饱和度(SpO2)、呼气末二氧化碳(PETCO2),并计算比较两组参数的变化情况。 结果 手术维持在同等熵指数下，切皮时两组平均动脉压均高于术前，手术进行至10分钟时丙泊酚组的MAP持续升高，当30分钟时，丙泊酚组的SE值低于七氟烷组。手术结束苏醒时，最终到达OAA/S评分和定向力恢复时间，两组无统计学意义。结论 两组在麻醉维持有效性和安全性及苏醒时间上无明显差别，七氟烷的血流动力学稳定性优于丙泊酚,熵指数与OAA/S评分有良好相关性.     

Control of the haemodynamic response to surgical stimuli in semi-closed circuit or closed circuit anaesthesia using a multifunctional anaesthesia system

This study compared the ability of the Zeus multifunctional anaesthesia system to control haemodynamic response to surgical stimulation in semi-closed (SCA) or closed circuit anaesthesia (CCA) modes. Fifty patients undergoing gynaecological surgery were randomly assigned to SCA or CCA. Anaesthesia was induced with 2 mg propofol and 0.9 mg/kg rocuronium, intravenously, and maintained using sevoflurane (minimum alveolar concentration [MAC], 1.0) using 2 l/min oxygen plus 2 l/min nitrous oxide (SCA 4 l/min group) or 50% oxygen plus 50% nitrous oxide (CCA group). An increase in mean arterial pressure (MAP) > 20% above baseline in response to surgical stimulation provoked a stepwise increase in sevoflurane (1.3 MAC and then 1.6 MAC), followed by fentanyl 1 pg/kg intravenously (rescue drug). The time required for MAP to return to within 10% of baseline was significantly shorter in the CCA group (6.4 +/- 3.6 min) compared with the SCA 4 l/min group (10.2 +/- 6.0 min). The percentage of patients requiring fentanyl was significantly greater in the SCA 4 l/min group than in the CCA group. In conclusion, CCA controlled acute haemodynamic responses to surgical stimuli more successfully and rapidly than SCA 4 l/min, using a multifunctional anaesthesia machine.     

End-tidal versus manually-controlled low-flow anaesthesia

During low-flow manually-controlled anaesthesia (MCA) the anaesthetist needs constantly adjust end-tidal oxygen (EtO₂) and anaesthetic concentrations (EtAA) to assure an adequate and safe anaesthesia. Recently introduced anaesthetic machines can automatically maintain those variables at target values, avoiding the burden on the anaesthetist. End-tidal-controlled anaesthesia (EtCA) and MCA provided by the same anaesthetic machine under the same fresh gas flow were compared. Eighty patients were prospectively observed: in MCA group (n = 40) target end-tidal sevoflurane (1 %) and EtO₂ concentrations (≥35 %) were manually controlled by the anaesthetist. In EtCA group (n = 40) the same anaesthetic machine with an additional end-tidal control feature was used to reach the same targets, rendering automatic the achievement and maintenance of those targets. Anaesthetic machine characteristics, amount of consumed gases, oxygen and sevoflurane efficiencies, and the amount of interventions by the anaesthetist were recorded. In EtCA group EtAA was achieved later (145 s) than in MCA (71 s) and remained controlled thereafter. Even though the target expired gas fractions were achieved faster in MCA, manual adjustments were required throughout anaesthesia for both oxygen and sevoflurane. In MCA patients the number of manual adjustments to stabilize EtAA and EtO₂ were 137 and 107, respectively; no adjustment was required in EtCA. Low-flow anaesthesia delivered with an anaesthetic machine able to automatically control EtAA and EtO₂ provided the same clinical stability and avoided the continuous manual adjustment of delivered sevoflurane and oxygen concentrations. Hence, the anaesthetist could dedicate more time to the patient and operating room activities.