A MODEL OF THE EXTRADURAL SPACE AND A REAPPRAISAL OF THE EXTRADURAL SPACE PRESSURE

A model is described which was used to study the genesis ofthe pressure in the extradural space. It consists of a Perspexouter tube, with perforations covered with rubber septa to allowthe insertion of needles, and Paul‘s tubing on the inside,representing the dura mater. The Paul's tubing is filled withwater through a constant head of pressure apparatus. The responseof the model to the insertion of an extradural needle and thereproduction of various clinical phenomena are described. Thepressure in the extradural space is discussed in relation tothe performance of the model.     

A REASSESSMENT OF THE VALIDITY OF THE ISO-SHUNT GRAPH

The iso-shunt diagram was introduced in 1973 to simplify theselection of the optimal inspired oxygen concentration in patientsundergoing intensive therapy. A further study of 25 patientsin a District General Hospital showed that plots of arterialPO₂ against inspired oxygen concentration closely follow predictediso-shunt lines. There was no significant difference in calculatedmean values for shunt with inspired oxygen concentrations between30 and 100%. Results are compared with other studies and itis suggested that some reported discrepancies may be explainedby the reduced response of many polarographic electrodes whenmeasuring high values for arterial PO₂ ^*Present adress: South Cleveland Hospital, Middlesborough, ClevelandTS4 3BW     

THE USE OF THE APPENDIX AS A CONTINENT CATHETERIZABLE STOMA

Purpose

We review the results of 5 years of using the unmodified appendix for reconstruction of neobladders and native bladders, and describe the mechanism of continence.

Materials and Methods

Between 1993 and 1997, 24 patients have undergone continent urinary diversion using the unaltered appendix. Median patient age at the time of surgery was 62 years. Patients were followed at the urological outpatient clinic for a mean of 18 months (range 7 to 47). Video urodynamic studies were performed once in the first 6 months postoperatively and repeated if there was any history of incontinence or bladder problems.

Results

Of the patients with an appendicovesicostomy onto the native bladder 80% were dry during the day and night. This figure was improved to 94% when 2 patients with incontinence catheterized more frequently. Patients with a neobladder were more likely to be continent and had a longer interval between catheterizations, which reflects the larger reservoir volume rather than better continence mechanism in these patients. The level of continence is at the appendiceal bladder junction in the native bladder and the appendicocecal junction in the neobladder, which is able to withstand reservoir pressures of 30 to 40 cm. water. Stress incontinence driven by abdominal pressure did not occur. Instead incontinence occurred when the bladder became over full and the pressure increased, or during an unstable contraction.

Conclusions

The appendix does not need to be tunneled through the bladder wall to achieve satisfactory continence. In a low pressure reservoir continence may be achieved simply by anastomosing the appendix directly onto the bladder or leaving it in situ when creating a neobladder.     

EVALUATION OF A NEW METHOD FOR THE CONTINUOUS MEASUREMENT OF THE DISTRIBUTION OF THE BLOOD FLOW BETWEEN THE TWO LUNGS

The magnitude of the pulmonary vasoconstrictor response to alveolarhypoxia may be studied by measuring the reduction in blood flowwhen one lung is ventilated with nitrogen. A radioisotope techniquehas been developed which permits the distribution of blood flowbetween the two lungs to be measured continuously. This techniquewas evaluated in dogs and found to be satisfactory.     

THE EVALUATION OF THE ISOLATED PERFUSED LIVER AS A MODEL FOR THE ASSESSMENT OF LIVER PRESERVATION

An ex vivo isolated perfused porcine liver model was tested to assess its suitability for rapid, reliable and relatively cheap testing of organ preservation solutions for liver transplantation. The model consists of a machine driven recirculating system incorporating an organ chamber. blood pump and membrane oxygenator. Autologous blood was used for perfusion for a period of 2 h at a temperature of 37°C. The model was tested with five groups of livers which had sustained varying degrees of injury ranging from minimally damaged to those known to be incapable of sustaining life when used for liver transplantation. The groups of livers were: (i) controls; (ii) preserved in University of Wisconsin solution (UW) for 6 h; (iii) preserved in an albumin-based extracellular fluid (ALB) for 6 h; (iv) preserved in UW for 18 h; and (v) preserved in ALB for 18 h. Bile production was found to be a reliable parameter of preservation damage. Changes in perfusate levels of aspartate aminotransferase, potassium, glucose and calcium also occurred in relationship to preservation damage. In contrast, weight gain of the liver, sequestration of the white cells and platelets in the liver. urea production and oxygen consumption were unreliable predictors of liver damage. Histology of biopsy specimens revealed apparently well preserved livers in all cases after preservation but before perfusion, but serious abnormalities after perfusion in long preserved livers, with features in these suggestive of damage to the sinusoidal endothelium. We believe that the model is a worthwhile adjunct to research into liver preservation.     

CARCINOMA OF THE STOMACH: THE NEED FOR A NEW APPROACH

An analysis was performed of 229 cases of carcinoma of the stomach presenting between 1970 and 1975 and followed up until 1980. The average age of the patients was 67 years with a range of 24 to 96 years. The predominant symptoms were weight loss, epigastric pain, anorexia, vomiting and an abdominal mass of two to 18 months duration. All cancers were adenocarclnomata, most commonly In the distal third of the stomach; most were bulky (T₃) on diagnosis and of poor histological differentiation. Some tumours had not spread to nodes but most had nodal involvement of the first and second order. Over half showed evidence of wide-spread dissemination at presentation. The operative mortality of all procedures Including curative resection, palliative resection and by-pass was high, reflecting the high exploration rate (81.6%), high resection rate (56%) and the extent and hazards of major operation. Total gastrectomy was associated with twice the operative mortality of subtotal gastrectomy. Five year survival was In each case 17.3% and 16.3% respectively but It should be noted that the larger, more bulky and infiltrative tumours could not have been dealt with by anything Jess than total gastric resection. Average survival time in the “curative” surgery group was 27.9 months and of all 229 patients presenting, only 11 (4.8%) were alive after five years. Factors which may lead to Improvement In this dismal outlook are discussed. Earlier diagnosis and multimodal chemotherapy as an adjunct to traditional surgery appear to offer the greatest prospects of Improvement.     

THE PERFORMANCE OF A SCAVENGING VALVE

A simple, compact and lightweight device for coupling activescavenging systems to shrouded breathing system valves is described.Provided a scavenging minute flow rate greater than the expiredgas volume is available, the unit can handle automatically changesin both variables. Optimal function is achieved with scavengingflows from about twice the discharged gas flow to about 50 litremm^–1 At these flows the valve can accommodate the outflowof gas-driven ventilators where driving gas and circuit gasare discharged through the same port There is no interferencewith expiratory valve function in the event of scavenging failure     

急性出血坏死性胰腺炎非手术治疗关键环节的研究——附83例分析

从1970年1月至1996年4月共收治急性出血坏死性胰腺炎(AHNP)病人160例,1980年以前以简化手术为主,1980—1990年期间以经典手术为主,1990年以后以非手术治疗为主。非手术治疗组的各种并发症及死亡率均低于手术治疗组(p<0.05)。并发症ARDS、胰腺脓肿、腹腔出血可能和手术打击有关。因此非手术治疗值得提倡和推广。采用非手术治疗的关键环节:(一)诊断要十分明确;(二)早期(发病3—5日内)以纠正内环境紊乱及减轻胰外器官损害为主;(三)中期(发病2—4周内)以防治胰腺坏死组织继发感染为主;(四)后期(发病4周后)以处理胰腺坏死组织引起并发症为主。     

A RANDOMIZED COMPARATIVE STUDY OF THE BANDLOOP VERSUS THE STANDARD LOOP FOR TRANSURETHRAL RESECTION OF THE PROSTATE

PURPOSE: The Bandloop is a new electroresection loop that is broader than the standard loop and thickens from front to back. We compared the safety and efficacy of the Bandloop to the conventional loop electrode for transurethral prostatectomy. MATERIALS AND METHODS: A randomized prospective study was performed on 53 patients with lower urinary tract symptoms and estimated prostatic volume greater than 30 ml. on transrectal ultrasonography. The Bandloop was used in 25 cases (Bandloop group) and standard loop was used in 28 (standard group). Surgical outcomes, including International Prostate Symptom Score, resected prostatic weight, operative time, uroflowmetry, post-void residual urine, postoperative catheterization period, time to disappearance of macrohematuria, and serial changes of hemoglobin and urinalysis, between the 2 groups were compared. RESULTS: A total of 23 Bandloop and 28 standard loop cases were evaluable. There was no difference in preoperative estimated prostatic volume (mean 44.7 versus 47.8 ml.), resected prostatic weight (36.5 versus 29.4 gm.) or operative time (61 versus 60 minutes) between the 2 groups. The ratio of resected weight-to-estimated prostatic volume was significantly greater in the standard group (81.4% versus 61.9%). There was no difference in postoperative catheterization period (3.3 versus 3.4 days) or time to disappearance of macroscopic hematuria (5.0 versus 5.0 days). Postoperative changes in symptom score (-15.1 versus -15.9), maximum flow rate (11.8 versus 16.3 ml. per second at 12 weeks) and residual volume (-31.6 versus -48.6 ml. at 12 weeks) demonstrated no significant difference between the 2 groups. There was no difference in intraoperative and postoperative bleeding estimated by serial changes in serum hemoglobin and urinalysis after surgery. No patient had major complications or required transfusion. CONCLUSIONS: Transurethral prostatectomy using the Bandloop is as safe and effective in achieving subjective and objective improvements as standard transurethral prostatectomy. However, our randomized study indicates that the Bandloop offers no advantage compared to the standard loop electrode for transurethral prostatectomy.     

A FELLOWSHIP IN THE USA: ESSENTIAL INFORMATION FOR THE AUSTRALASIAN MEDICAL GRADUATE

Background : There have been many recent changes to the immigration and educational requirements necessary to obtain both clinical and research positions in the USA. This paper describes these requirements in detail and examines the cost of obtaining a position. Methods : An extensive review of Medline and relevant documents from educational and immigration bodies is undertaken in addition to personal and peer experience of the processes necessary to fulfil educational and immigration requirements for funded medical positions in the USA. A cost analysis is performed based upon the latest charges for exam requirements and visa fees. A ‘minimum’ cost for fulfilling exam and visa requirements only and a ‘likely’ cost (which represents a more realistic appraisal of the expenses likely to be incurred) are investigated. Results : This review shows that many recent changes have made the attainment of a position difficult and expensive. Much foresight and planning is required to obtain the necessary requirements for medical licensure and to obtain working visa status in addition to the application for the position itself. The cost analysis reveals that the minimum cost is $4050 (AU$) and the ‘likely’ cost is $8600 (AU$). Conclusion : Australasian trainees and Fellows need to be fully aware of the difficulties and expenses likely to be encountered in order to make an informed decision with regard to overseas training in the USA.     

DELIBERATE HYPERVENTILATION IN THE TREATMENT OF A CRUSH INJURY OF THE CHEST: A Case Report

A case of severe crush injury of the chest associated with afracture-dislocation of the thoracic spine is reported. Thechest was stabilized for fourteen days by intermittent pressureventilation. Analgesia and sedation were achieved by constant hyperventilation,maintaining an arterial blood pH in excess of 7.5. No analgesicor sedative drugs were needed and the patient was pain-free,calm and co-operative. His impressions during the period of. controlled hyperventilation are recorded. A complete examinationof acid-base balance was carried out on alternate days. Thetreatment of similar severe chest injuries by deliberate hyperventilationis suggested.     

A STUDY OF THE EFFECTS OF DEXCLAMOL AS THE NEUROLEPTIC COMPONENT IN NEUROLEPTANAESTHESIA

In a double-blind cross-over study in dogs, dexclamol was comparedwith droperidol as the neuro-leptic component of a neuroleptanalgesiccombination. Fentanyl was the narcotic analgesic. Neuro-leptanaesthesiawas induced with a mixture of the neuroleptic, the analgesicand nitrous oxide in oxygen. Dexclamol 200 ng/kg i.v. was aseffective as droperidol at the same dose in inducing neuro-lepsyand in supplementing nitrous oxide anaesthesia. Changes in heartrate, respiratory rate and rectal temperature in the animalstreated with dexclamol were not different from those observedin the animals treated with droperidol. A comparison of theadrenolytic properties of dexclamol and droperidol was madeon the isolated rabbit aortic strip. Both compounds produceda parallel shift to the right of the noradrenaline cumulativedose-response curves, indicating competitive antagonism. ThepA2 values showed dexclamol to be approximately 15 times lesspotent than droperidol in inhibiting the noradrenaline-inducedcontraction of the rabbit aortic strip     

A BONY TUMOUR OF THE BREAST

Oesteosarcomas of the mammary glands are rare tumours and their mode of origin is controversial. The following case report records the clinical features and histological appearances of an osteosarcoma arising in a 50 year old female. The case described supports the view that most of these osteosarcomas arise from long standing fibroadenomas.     

COMPETENCY AND THE COLONOSCOPIST A LEARNING CURVE

The first 334 consecutive unassisted studies of a trainee colonoscopist were audited to analyse the relationship between experience and a target 90% completion rate of colonoscopy. The cumulative sum (cusum) score was applied to examine the time trend for the attaining of the target 90% completion rate. This technique described a learning curve which showed, in this instance, that approximately 100 studies were necessary before a 90% completion rate was approached. A further 100 studies were required before this target completion rate was achieved consistently. A trend for continued improvement above the 90% completion rate level was also seen after 200 studies. Polypectomy was completed in 117 of the 123 studies where indicated. Cusum analysis may be a useful method for monitoring the progress of the trainee colonoscopist and the attainment of satisfactory competence. Training requirements, therefore, might better emphasize the attainment of an acceptable completion rate rather than an arbitrary quota per se.