EFFECTS OF SUBARACHNOID SPINAL NERVE BLOCK AND ARTERIAL PCO2 ON COLON BLOOD FLOW IN THE DOG

Changes in colon blood flow in greyhounds were measured in responseto acute changes in arterial PCO₂, before and after spinal nerveblock. Colon blood flow increased significantly after spinalnerve block, irrespective of PCO₂. The findings may be of clinicalimportance in man. ^*University Department of Anaesthesia, The General Hospital,Gwendolen Road, Leicester. Department of Surgery, Royal Infirmary, Glasgow. Victoria Infirmary, Glasgow.     

VOLTAGE FIELDS SURROUNDING NEEDLES USED IN REGIONAL ANAESTHESIA

Using a bench model, we have studied the voltage fields surroundingboth insulated and uninsulated needles used in regional anaesthesia.The findings were compared with earlier computer predictionswhich suggested that the fields would be markedly differentfor the two types of needle. The results confirm that the fieldsdiffer markedly and suggest that the use of insulated needlesmay not necessarily improve the accuracy of nerve location andthat uninsulated needles may be more appropriate. ^*Present addresses: Department of Anaesthetics, Hull Royal Infirmary,Hull, Humberside. Droitwich Knee Foundation, Saga House, SansomePlace, Worcester Present addresses: Droitwich Knee Foundation, Saga House, SansomePlace, Worcester.     

METHOXYFLURANE ANALGESIA FOR BURNS DRESSINGS: EXPERIENCE WITH THE ANALGIZER

Methoxyflurane has been used to provide analgesia for burnsdressings on sixty occasions in eleven patients. It was administeredby way of a new, disposable vaporizer, the Analgizer, whichis described. Three patients required either supplementary analgesicsor tranquillizers. No side effects were noted, and patient acceptanceof the Analgizer was good. This method is thought to representan advance over previous methods of analgesia for burns dressings,since there is no undue sedation, pre-operative starvation isunnecessary, and venepunctures are avoided. ^*This device is not yet marketed in the United Kingdom. Present address:Department of Anaesthesia, Royal HampshireCountyHospital, Romsey Road,Winchester Present address:Department of Surgery, University of Chicago,Chicago,Illinois 60637     

HAEMODYNAMIC RESPONSES TO ENFLURANE ANAESTHESIA AND HYPOVOLAEMIA IN THE DOG, AND THEIR MODIFICATION BY PROPRANOLOL

The haemodynamic responses to minumum equipotent concentrationsof halothane and enflurance were compared in seven dogs. Thehaemodynamic responses to increasing concentrations of enflurane,and to induced hypovolaemia during enflurane anaesthesia, werestudied in the same dogs, both before and after administrationof propranolol 0.3 mg kg^-1 i.v. In equipotent concentrations,enflurane caused marginally greater impairment of left ventricularfunction than halothane, and caused a dose-dependent reductionof arterial pressure, cardiac output and myocardial contractility.Following administration of propranolol, these haemodynamiceffects of enflurane were marked, and withdrawal of 20% of estimatedblood volume was tolerated poorly. ^*Present addresses :Department of Anaesthetics, St Vincent'sHospital,Darlinghurst, N.S.W. 2010, Australia. Present addresses :Department of Anaesthesia, University ofBristol,Royal Infirmary, Bristol BS2 8HW. Present addresses :Department of Anesthesiology, Universityof California,San Francisco Medical Center, San Francisco, U.S.A. Present addresses :Department of Anaesthesia, Flinders Universityof South Australia, Bedford Park, South Australia 5042.     

EXTRADURAL METHADONE AND BUPIVACAINE IN LABOUR

We performed a double-blind placebocontrolled study of the effectsof extradural administration of methadone 5 mg or saline, followedby bupivacaine, in 42 women in early labour. Motor block andpain scores were significantly less in the methadone group.The requirement for bupivacaine also was reduced by methadone,but this was not statistically significant. There were no troublesomeside effects attributable to methadone. ^*Department of Anesthesiology, University of Maryland Schoolof Medicine, 22 South Greene Street, Baltimore, Maryland 21201,U.S.A. Anaesthetic Department, Leicester Royal Infirmary, LeicesterLE1 5WW.     

THE EFFECTS OF VARIATIONS IN END-EXPIRATORY INFLATION PRESSURE ON CARDIORESPIRATORY FUNCTION IN NORMO-, HYPO AND HYPERVOLAEMIC DOGS

The effects of altering end-expiratory inflation pressure werestudied in mechanically ventilated dogs in the normo-, hypo-and hypervolaemic state. The mean fall in cardiac output resultingfrom an increase in end-expiratory pressure was smaller in thehypervolaemic group than in the other two groups. A positiveend-expiratory pressure increased the mean deadspace/tidal volumeratio in all groups. A negative end-expiratory pressure increasedvenous admixture, particularly in the over-transfused animals,but the increase was not significant in the hypovolaemic group.A negative end-expiratory pressure did not affect deadspace/tidalvolume ratio. ^*Radcliffe Infirmary, Oxford Western Infirmary, Glasgow St George's Hospital, London Paddington Green Technical College, London     

A NEW TECHNIQUE FOR DOMICILIARY FLYING SQUAD ANAESTHESIA

A technique of domiciliary midwifery anaesthesia using Entonoxon a demand basis and minimal trichloroethylene is described.The method employs apparatus using the drawover principle, andalso includes facilities for neonatal resuscitation. ^*Liverpool Maternity Hospital, Liverpool 7. Department of Anaesthetics, Bristol University. Whiston Hospital, Prescot, Lanes.     

DELAYED EXCITATORY REACTION FOLLOWING INTERACTION OF COCAINE AND MONOAMINE OXIDASE INHIBITOR (PHENELZINE)

A case report is presented in which a patient receiving themonoamine oxidase inhibitor, phenelzine, developed a delayedexcitatory reaction following administration of topical cocainespray during anaesthesia for vocal cordsurgery. The pharmacologicalbasis of the drug interaction is discussed. ^*Department of Anaesthesia, St Bartholomew's Hospital, WestSmithfield, London EC1A 7BE. Shackleton Department of Anaesthetics, Southampton General Hospital,Tremona Road, Southampton S09 4XY. Harefield Hospital, Uxbridge, Middx UB9 6JH.     

DANGERS OF ANAESTHESIA IN MUNCHAUSEN'S SYNDROME

Patients with Munchausen's syndrome often undergo multiple surgicaloperations under general anaesthesia. They tend to have multipleexposures to routinely used anaesthetic agents. A patient withMunchausen's syndrome who developed an anaphylactoid reactionto thiopentone is described and the importance of obtainingprevious case notes is stressed. ^*Present addresses: Department of Anaesthesia, South ClevelandHospital, Marton Road, Middlesbrough, Cleveland TS3 4BW. Department of Anaesthesia, Edinburgh Royal Infirmary, EdinburghEH3 9YW.     

USE OF REGIONAL ANAESTHESIA IN A PATIENT WITH ACUTE PORPHYRIA

The porphyrias are inherited disorders of haemmetabolism, acuteattacks of which may be precipitated by anaesthesia, surgeryand pregnancy. The principal clinical feature of the diseaseis an acute neuropathy. A patient with acute intermittent porphyriawas given bupivacaine as part of a regional anaesthetic forCaesarean section. The course of anaesthesia was uneventful. ^*Department of Anaesthesia, Royal Infirmary, 84 Castle Street,Glasgow. Department of Anaesthesia, University of Uppsala, Uppsala, Sweden.     

THE CARDIORESPIRATORY EFFECTS OF HAEMORRHAGE AND OVERTRANSFUSION IN DOGS

Changes in cardiorespiratory function resulting from haemorrhageand overtransfusion were measured in forty-seven dogs duringcontrolled ventilation. In the animals bled to a mean arterialpressure of 70 mm Hg there were significant reductions in arterialPco₂, carbon dioxide output and oxygen consumption, cardiacoutput and total venous admixture. In the animals transfusedto a mean central venous pressure of 15 mm Hg there was a significantfall in total thoracic compliance and arterial Po₃ and significantincreases in the alveolar-arterial Po₃, difference and carbondioxide output. ^*Radcliffe Infirmary, Oxford. Western Infirmary, Glasgow. Mount Sinai School of Medicine, New York, U.S.A. Vancouver General Hospital, Vancouver, Canada.     

A CASE OF MASSIVE ASPIRATION OF GASTRIC CONTENTS DURING OBSTETRIC ANAESTHESIA: Treatment by Tracheostomy and Prolonged Intermittent Positive Pressure Ventilation

A case is described of massive aspiration of liquid gastriccontents into the lungs of an obstetric patient undergoing generalanaesthesia. Pre-operative treatment with oral alkali to neutralizegastric acid did not prevent a severe reaction in the lungs.Treatment was by general supportive measures and long-term intermittentpositive pressure ventilation via a tracheostomy. Great difficultywas experienced in ventilating the lungs because of their lowcompliance and the large physiological deadspace. Recovery wascomplicated by a severe reduction in pulmonary diffusing capacityand by the development of tracheal stenosis. The factors influencingthe treatment and complications are discussed. ^*Present addresses:United Oxford Hospitals Present addresses:Tottenham Group of Hospitals Present addresses:St. George's Hospital, London     

THE EFFECTS OF VARIATIONS OF INSPIRATORY FLOW WAVEFORM ON CARDIORESPIRATORY FUNCTION DURING CONTROLLED VENTILATION IN NORMO-, HYPO- AND HYPERVOLAEMIC DOGS

The effects of changes in applied positive pressure waveformduring inspiration were studied in anaesthetized dogs mechanicallyventilated with air in the normo-, hypo- and hypervolaemic states.Four waveforms were used (sine, square, late peak and earlypeak flow patterns), these being delivered from a speciallyconstructed ventilator which behaved as a volume preset machinein the inspiratory phase. Controlled ventilation was performedat a constant frequency of 20 respirations per minute at a fixedinspiratory: expiratory ratio of 1:2. None of the waveformsused was found to produce significant changes in cardiorespiratoryfunction within any of the three states of blood volume. ^*Radcliffe Infirmary, Oxford. Paddington Green Technical College, London. Western Infirmary, Glasgow.     

THE AMNESIC EFFECT OF DIAZEPAM (VALIUM)

A double-blind trial of intravenous diazepam (0.24 mg/kg) versussaline was carried out on twelve young intelligent male volunteersto examine the amnesic effect of the drug. Complex psychologicaltesting extended over a 2-hour period. Dense anterograde amnesiawas found for approximately 10 minutes with a less severe impairmentof memory persisting at least half an hour after injection.It is considered that the memory difficulties were not due toserious reduction of level of consciousness but do focus onthe input or "consolidation" processes rather than on retrieval.Further studies are needed to define more clearly the natureof the deficit. ^*Whiteley Wood Clinic, Woofindin Road, Sheffield S10 3TL. Dept. of Anaesthetics, Royal Infirmary, Sheffield 6. Dept. of Psychology, University of Sheffield, Western Bank,Sheffield S10 2TN.     

COMPARISON OF TWO METHODS OF AXILLARY BRACHIAL PLEXUS ANAESTHESIA

Comparison of the trans-arterial and Winnie techniques of axillarybrachial plexus block was made in two groups of patients. Thisstudy did not find any statistical difference between the twotechniques. Present address, for correspondence: Anaesthetic Department,Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF.     

RADIOGRAPHIC STUDY OF INTERCOSTAL NERVE BLOCKADE IN HEALTHY VOLUNTEERS

The spread of solutions injected to the intercostal space wasstudied in 10 healthy volunteers. Up to 20 ml of a 50:50 mixtureof local anaesthetic solution and a radiopaque dye was injectedthrough a modified extradural catheter placed in an intercostalspace at the posterior angle of the rib. Radiographic filmsdemonstrated spread by an extrapleural route into adjacent intercostalspaces and this was confirmed by the occurrence of analgesiain the corresponding dermatomes. The relevance of these resultsto clinical practice is discussed. ^*University Department of Anaesthesia, Royal Victoria Infirmary,Newcastle upon Tyne NE1 4LP. Department of Anaesthesia, University of Sheffield, SheffieldS10 2RX     

EFFECTS OF VARYING INSPIRATORY FLOW WAVEFORM AND TIME IN INTERMITTENT POSITIVE PRESSURE VENTILATION I: INTRODUCTION AND METHODS

A general review of the physiological alterations with artificialventilation is presented with particular emphasis on the alterationof inspiratory time and flow waveform. The general methods andphysiological calibration procedures used in a more elaboratestudy of inspiratory time and waveform effects are described,with the results of testing these methods showing that the modelis satisfactory. ^*Present addresses:Department of Anaesthesia, University ofOtago, New Zealand. Present addresses:Princess Margaret Hospital, Swindon, Wilts. Present addresses:St Vincent's Hospital, Melbourne, Australia.     

THE PRESSOR RESPONSE TO VENOUS CANNULATION: ATTENUATION BY PRIOR INFILTRATION WITH LOCAL ANAESTHETIC

We have compared the cardiovascular response to insertion ofan 18-gauge venous cannula in 40 healthy patients. In 20 ofthe patients, cannulation was preceded by infiltration of localanaesthetic. Both rate-pressure product and mean arterial pressureincreased significantly (? <0.01) compared with baselinewhen no local infiltration was used, but there was no significantchange from baseline when infiltration with local anaestheticpreceded cannulation. We conclude that there is a significantpressor response to venous cannulation which is obtunded byprior infiltration with local anaesthetic. We recommend, therefore,that s.c. injection of lignocaine should be considered beforeinsertion of an i. v. cannula, especially in the high risk patient.(Br. J. Anaesth. 1993; 70: 519–521) ^*Department of Anaesthesia, Leicester Royal Infirmary,LeicesterLEI 5WW. Department of Anaesthesia, Royal Hallamshire Hospital, Sheffield.     

SEDATION FOR ENDOSCOPY: MIDAZOLAM OR DIAZEPAM AND PETHIDINE?

One hundred patients received either diazepam given with pethidine,antagonized with nalo-xone, or midazolam alone in a double-blindrandomized study of sedation for upper gastro-intestinal endoscopy.Midazolam produced better amnesia for the procedure (P <0.0001) but diazepam and pethidine resulted in less retchingduring the procedure (P < 0.01) and less sedation after theprocedure, as judged by a simple performance test (P < 0.02)and patient recall of results (P < 0.02). ^*Department of Respiratory Medicine, East Birmingham HospitalBirmingham Department of Medicine, Section of Dermatology, University ofWales College of Medicine, Cardiff Department of Radiology, Royal Hallamshire Hospital Sheffield     

AN EVALUATION OF GAMMA-HYDROXYBUTYRIC ACID IN PAEDIATRIC PRACTICE

Gamma-hydroxybutyric acid was used as a sedative for 54 childrenundergoing cardiac catherization and as a form of anaesthesiain 159 children undergoing paediatric surgery and various paediatricinvestigations. In 16 of the cardiac group and 22 of the surgicalgroup, an assessment of blood-gas status was made. Clinicalimpressions were favourable and the biochemical findings underlinethe safety, efficacy and usefulness of this drug in paediatricpractice. ^*Department of Cardiology, Newcastle General Hospital, Newcastleupon Tyne. Department of Surgery, The Hospital for Sick Children, GreatOrmond Street, London W.C.I. The Maudsley Hospital, Denmark Hill, London S.E.5.