Evaluation of the Greenbaum sub-Tenon's block

A prospective, randomized blind study was conducted in 40 patientsundergoing phacoemulsification and posterior chamber intraocularlens implantation. They received anaesthetic infiltration of2% lidocaine with 1:200 000 epinephrine and hyaluronidase150 U ml^–1 in a volume of 2, 3, 4 or 5 mlinto the sub-Tenon’s fascial space through a Greenbaumcannula after a conjunctival incision. Reduction of ocular movements,anaesthesia, pain on injection and any incidental complicationswere recorded. Akinesia and anaesthesia occurred within 5 minwith 4 and 5 ml of local anaesthetic, and no supplementaryinjections were required. There were marked reductions in thefrequency of forced eyelid movements with these volumes. Chemosisand conjunctival haemorrhage were noted in the majority of patientsbut caused no intraoperative problems. Approximately 10–15%of patients reported slight discomfort at the time of injection.Four to 5 ml of 2% lidocaine with 1:200 000 epinephrineand 150 U ml^–1 of hyaluronidase is the optimumvolume to achieve adequate akinesia, anaesthesia and reductionof lid movements during the Greenbaum sub-Tenon’s block. Br J Anaesth 2001; 87: 631–3     

Transoesophageal echocardiography in cardiac and vascular surgery: implications and observer variability

Transoesophageal echocardiography (TOE) has gained widespreadacceptance among cardiac anaesthetists as a tool to facilitateperi-operative decision-making. This observational study analysesthe impact of TOE and its inter-observer variability on intra-operativepatient management during cardiac and major vascular surgery.From June 1996 to December 1998, standardized reports were obtainedfrom 11 anaesthetists in 1891 adult cardiac and vascular surgerypatients undergoing routine biplane or multiplane TOE. Inter-observervariability and the difference between variables of interestwere tested using the chi-squared test or factorial analysisof variance as appropriate. TOE examinations were performedbefore and after the operation; 1673 (88.5%) patients underwentcardiopulmonary bypass (CPB), and 218 (11.5%) patients had surgerywithout CPB, including 42 (2.2%) coronary revascularizations.In 923 patients (49%), TOE provided additional information thatinfluenced the patient’s therapy. In 968 patients (51%),TOE had only minor or no impact on clinical decision-making.In two patients (0.10%) the scheduled operation was not performed,and in another two patients the TOE examination led to majorcomplications. Observer-dependent variables were: implicationsof TOE for intra-operative decision-making (P<0.0001), estimationof image quality (P<0.0001), pre-operative left ventricularfractional area change (FAC) (P=0.0026), difference betweenpre-operative FAC and post-operative FAC (P=0.033), and requestsfor supervision (P<0.0001). There was no significant differencein the case mix between observers. TOE had an important impacton intra-operative patient management. Inter-observer variabilitywas significant for several variables but not for the frequencyof additional surgical procedures. Br J Anaesth 2001; 86: 497–505     

Epidural haematoma after dural puncture in a parturient with neurofibromatosis

A case of epidural analgesia in a parturient with neurofibromatosis(von Recklinghausen’s disease) complicated by dural punctureand epidural haematoma is described and the management of thecase is discussed. The case emphasizes the need for antenatalassessment of parturients with neurofibromatosis in order thatthe necessary investigations can be arranged and informed consentfor analgesia and anaesthesia can be obtained. Br J Anaesth 2001; 87: 932–4     

Intra-operative and post-operative hypercapnia leading to delayed respiratory failure associated with transanal endoscopic microsurgery under general anaesthesia

We present an unusual case of hypercapnia and surgical emphysemaduring transanal endoscopic microsurgery, which led to delayedpost-operative ventilatory failure. The hypercapnia and surgicalemphysema were secondary to rectal insufflation with carbondioxide used to facilitate visualization and resection of arectal tumour. Despite a return to wakefulness after surgery,the patient’s level of consciousness deteriorated in therecovery area as a result of hypercapnia. The Pa_CO2 rose to16.8 kPa because of absorption of carbon dioxide from the surgicalemphysema. On close examination, surgical emphysema was identifiedin unusual areas, including the anterior abdominal wall, bothloins, both groins and the left thigh. Reventilation was requireduntil these unusual carbon dioxide stores had dissipated. Wediscuss the need for prolonged post-operative vigilance in patientswith surgical emphysema secondary to carbon dioxide insufflation,and the risk of delayed ventilatory failure. Br J Anaesth 2001: 86; 586–9     

面神经液压与面神经电图的相关性研究

目的　探讨面神经电图作为面神经减压手术指征的病理生理学基础。方法　利用电生理仪和伺服微变量微压系统 ,对正常和压榨伤后面瘫不同时期的豚鼠 ,作面神经电图检查 ,再采用微创测压法进行面神经液压的测量 ,得出面神经损伤后不同时期的面神经动作电位降幅及相应的面神经液压 ,并观察不同时期面神经光镜和电镜下的组织学改变。结果　面神经损伤 3d至 3周 ,随着面神经液压的升高 ,面神经动作电位降幅百分数亦增加 ,二者间有明显相关性 ,损伤后 2周和 3周 ,面神经液压和面神经动作电位降幅的相关系数分别为 0 88和 0 51。神经液压的变化与面神经Wallerian变性各期组织学改变相一致。结论　在面瘫 3周内 ,面神经电图的改变可间接反映面神经液压的变化 ,并可为面神经减压术的时机提供客观、可靠的实验依据。     

蛋白质不稳定性及其分析技术

蛋白质不稳定性包括两种形式：化学不稳定性和物理不稳定性，这两种不稳定性可采取不同的分析技术。了解蛋白质不稳定性及其分析技术在生物工程药物的质量控制中有十分重要的作用。     

Surgical Techniques to Facilitate Endoscopic Second-Look Mastoidectomy

Objectives/Hypothesis: Mastoidoscopy has shown to be a safe, effective alternative to traditional second-look mastoidectomy. This study was undertaken to review surgical modifications to facilitate successful mastoidoscopy. Study Design: Retrospective database review of all surgical procedures performed by the senior author (t.j.h. ) since January 1995. All surgeries were performed in a tertiary hospital setting. Results: Fifteen second-look procedures were performed in this series. Five were performed endoscopically, 10 with traditional techniques. In the traditional surgeries five were prior to the use of endoscopy, five had contraindications to endoscopic mastoidectomy. There were six residual cholesteatomas in the series, one in the endoscopic cases (20%), and five in the traditional cases (50%). No cholesteatomas were identified with microscopic examination performed after endoscopy. There were no complications in the series. Mastoidoscopy gives limited access to the mesotympanum, eustachian tube and, in particular, the sinus tympani. The creation of a wide extended facial recess with removal of the buttress at the fossa incudis and removal of the incus and head of the maleus will facilitate inspection of the middle ear. Additional techniques are necessary to view the sinus tympani. The fallopian bridge technique, and the infratympanic extended facial recess technique may allow better visualization of the middle ear. Conclusion: Mastoidoscopy offers a safe alternative to traditional techniques for second-look surgery. The morbidity appears similar to traditional techniques.     

Spiral CT of the neck: When do neck malignancies delineate best during contrast enhancement?

The aim of this study was to determine the time of best contrast of neck malignancies in contrast-enhanced CT. The CT was done in 20 patients with squamous cell carcinoma using a standard protocol (100 ml contrast agent at 2 ml/s). Dynamic series of the tumors were performed (scan interval 6 s). In all relevant structures of the neck, densities were measured to obtain time-density curves. The best tumor contrast was measured > or =50 s after the start of the injection, and the best contrast of lymph nodes < or =75 s. For staging and volume measurements of neck primaries the best achievable contrast is necessary. Using the examined single-bolus technique, spiral CT allows a combination of perfect tumor contrast with a good contrast between lymph nodes and neck vessels between 50 and 75 s after starting the injection.     

A pharmacodynamic analysis method to determine the relative importance of drug concentration and treatment time on effect

Purpose: The pharmacodynamics of most drugs follow the empirical relationship, Cⁿ × T=h, where C is drug concentration, T is exposure time and h is drug exposure constant. The value of n indicates the relative importance of C and T in determining the effect. An n value greater than 1.0 indicates that for two infusions that produce the same C × T, a short infusion that delivers high concentrations over a short duration will produce a greater Cⁿ × T and therefore a greater effect, compared to a long infusion that delivers lower concentrations. The reverse is true for an n value less than 1.0 and would support the use of a slow infusion. Hence, it is important to determine the n values and whether the n value significantly differs from 1.0. This report describes a three-step method for this purpose. Methods: First, we obtained experimental data on the relationship between drug concentration, treatment time and effect, and analyzed the data with a three-dimensional surface response method to obtain the pharmacodynamic model parameters and the magnitude of data variability. The experiments used mitomycin C and two human cancer cell lines, i.e. bladder RT4 and pharynx FaDu cells. The n values obtained from four experiments ranged from 1.04 to 1.16 for FaDu cells and from 1.14 to 1.46 for RT4 cells. The variability in the effect data decreased from 11.9% at 0% effect to 6.14% at 100% effect. Second, these results were used with Monte Carlo simulations to generate 100 concentration-time-effect data sets, which contained randomly and normally distributed data variability comparable to the experimentally observed variability, for each experimentally determined n value. This is analogous to performing 100 experiments under the same experimental conditions. Third, we analyzed the simulated data sets to obtain 100 estimated n values. The frequency with which these estimated n values fell above or below 1.0 indicated the probability that the experimentally determined n value used in the Monte Carlo simulations was truly different from 1.0. We defined this frequency for individual experiments as F_one, and calculated the overall probability for multiple experiments (F_multiple). A probability of greater than 97.5% (i.e. P < 0.05 for a two-tailed test) was considered statistically significant. Results: Analysis of the mitomycin C pharmacodynamic data yielded F_one and F_multiple of 99% to 100% for FaDu and RT4 cells, indicating that the n values for these cells were significantly higher than 1.0. A comparison of the statistical significance of the n value analyzed by the three-step pharmacodynamic analysis method, a conventional statistical method such as the Student's t-test and nonlinear regression analysis, indicated two advantages for the pharmacodynamic method: fewer experiments were required (theoretically only one experiment with three replicates would be sufficient) and a higher statistical significance of the n value was obtained. Conclusions: In summary, the three-step pharmacodynamic study design and analysis method can be used to define the relative importance of drug concentration and treatment time on drug effect. Received: 19 May 1999 / Accepted: 15 September 1999     

A quality assurance audit: Phase III trial of maximal androgen deprivation in prostate cancer (TROG 96.01)

In 1997 the Trans‐Tasman Radiation Oncology Group (TROG) performed a quality assurance (QA) audit of its phase III randomized clinical trial investigating the effectiveness of different durations of maximal androgen deprivation prior to and during definitive radiation therapy for locally advanced carcinoma of the prostate (TROG 96.01). The audit reviewed a total of 60 cases from 15 centres across Australia and New Zealand. In addition to verification of technical adherence to the protocol, the audit also incorporated a survey of centre planning techniques and a QA time/cost analysis. The present report builds on TROG’s first technical audit conducted in 1996 for the phase III accelerated head and neck trial (TROG 91.01) and highlights the significant progress TROG has made in the interim period. The audit provides a strong validation of the results of the 96.01 trial, as well as valuable budgeting and treatment planning information for future trials. Overall improvements were detected in data quality and quantity, and in protocol compliance, with a reduction in the rate of unacceptable protocol violations from 10 to 4%. Audit design, staff education and increased data management resources were identified as the main contributing factors to these improvements. In addition, a budget estimate of $100 per patient has been proposed for conducting similar technical audits. The next major QA project to be undertaken by TROG during the period 1998–1999 is an intercentre dosimetry study. Trial funding and staff education have been targeted as the key major issues essential to the continued success and expansion of TROG’s QA programme.