The overriding principle of military surgery is the delayed primary suture of wounds. Therefore. by definition, battle casualties will receive more than one anaesthetic for the treatment of their injuries. The use of the Triservice anaesthetic apparatus (TSA) has bccii well tried and documented.',' It is a drawover system that uses ambient air iis the primary carrier gas, and halothane and trichlorocthylcnc a the volatile anaesthetic agcnts.However, in view of current opinions about liver damage due 10 repeated halothane it would be prcferablc if this agent were no1 used in the first instance. In addition, the manufacture of trichloroethylene has been threatened in the past and the future production of this agent cannot be guaranteed. The use of the newer inhalational agents, entlurane and isoflurane. has been rec o n~m c n d c d .~ Unfortunately. enflurane, which does have analgesic p r o p e r t i~s .~ has a high MAC and isoflurane, at present. is very expensive.We felt that ;I total intravenous technique is an obvious altcrnative in the treatment of battle casualties. This study was therefore designed to assess the suitability of such a technique using a mixture that contained ketamine, niidamlarn and vecuronium, ;iccuratcly dclivered intravenously by ineans of a syringe pump. Ketaminc has becn uscd widely as the induction and maintenance drug of choice for trauma cases but the high incidence of unpleasant side effects has limited its acceptance. Vecuronium bromide, one of the rnore recently introduced non-depolarising muscle relaxants. has been used because it is available as an anhydrous powder and therelhre stores well. Vccuronium is frcc of advcrsc circulatory effects and the incidence of release of histamine is minirnal.'j It is our contention that all battle casualties will have a full stomach, irrespective of the interviil between timc of injury and time of surgery. Therefore, tracheal intubation is mandatory and intermittent positive pressure venlilation can be iiscd for the duration of the surgical procedure. Another essential recluiremcnt for w x surgery is (hat patients should recover quickly and be able to maintain clear airway as soon as possible. MrriiorliOne hundred patients, 36 male and 64 Ccmale. age range 16-50 years. who presented for elective abdominal, thoracic or body surface surgery at this hospital wcre studied. All patients were in ASA classes 1 and 2. It MBS estimated that their operations would last at least 45 minutes. Patients with a past medical history of psychiatric illness. with hypertension and those with a history of ;I previous ccrcbrovascular iiccidcnt wcrc not studied. All patients were seen prc-operativcly. Thc following details were recorded: initials, sex, body weight. relevant medical history and physical findings. All were prcnicdicated with papavereturn and hyoscinc one hour preoperatively. Monitoring of the electrocardiogram a n d blood pressure (Dinamap) wis commenced on arrival in the anaesthetic room and a vein on thc dorsiun of the hand or forearm was cannulate...
SummaryBench testing was carried out to establish whether the vapour output from an OMV50 vaporizer, as used in the Triservice apparatus, difers according to whether the carrier gas is either drawn or pushed through the vaporizer. Results show that the diferences in output concentration between the two modes were clinically insign8cant. Key wordsAnaesthetic techniques; drawover, inhalation. Equipment; Triservice anaesthetic apparatus.The Triservice apparatus based on the use of the OMVSO vaporizer (Penlon) [l] was primarily designed to function as a drawover system for spontaneously breathing patients. When used for positive pressure ventilation this principle holds true with the vaporizer upstream of the self-inflating bag or suitable mechanical ventilator. The ventilator is used to suck the gas through the vaporizer instead of the patient's own inspiratory effort.The British Army field anaesthesia kit includes the Cape TC50 ventilator (Penlon) which can be used with the Triservice apparatus [2] (Fig. 1). This is a small, robust and simple ventilator. It works on the principle of a rubber bellows which sucks in fresh gas when it is expanded by a spring. The gas is then expelled from the bellows under the influence of a piston pushed by a cam. This is powered by a 240 v AC electric motor. There is a one-way valve on the gas intake and a Laerdal Resuscitator non-rebreathing valve at the patient end of the system. Both these valves are required to ensure the correct flow of anaesthetic gas. The ventilator is designed so that the two OMV50 vaporizers can be placed on the built-in back-bar. The apparatus is conventionally used as a drawover system, with the ventilator downstream of the supplementary oxygen and the vaporizers. This arrangement works very well [3].Unfortunately, in the field, this configuration of the apparatus is not always convenient. It may become necessary, for a variety of reasons, to have the vaporizer between the ventilator and the patient. These reasons include: (1) The Triservice apparatus was originally designed to use a self-inflating bag as the means of performing intermittent positive pressure ventilation (IPPV). The complete set-up could then be sat easily upon the shelf at the head of the Macvicar operating table. The TC50 ventilator is significantly heavier than a self-inflating bag, therefore in field use it is usually more convenient and practical to position it on the ground. In order to view the agent level window, or @ able to adjust the control lever whilst holding a mask on the patient's face, it is far easier and safer to position the OMV50 vaporizer on the shelf attached to the table rather than attach it to the back-bar of the TCSO. This means that the vaporizer must be between the ventilator and the patient. (2) The length of tubing required for the breathing system in drawover set-up is considerably greater than that required if the vaporizer can be positioned on the shelf between the ventilator and the patient. When lengths of tubing get lost or damaged in the field this ...
Key wordsAnaesthetic techniques; total intravenous. Anaesthetics, intravenous; ketamine, propofol.In a previous study' we showed that a total intravenous anaesthetic technique with a mixture of ketamine, midazolam and vecuronium was a safe, simple and reliable alternative to inhalational anaesthesia for use in the field, and the method was proposed as a substitute for use in general civilian practice. We decided to compare this technique with another form of total intravenous anaesthesia for a relatively short surgical procedure, laparoscopy. Propofol has been used both alone2s3 and in combination with alfentani14 to provide anaesthesia for a variety of surgical procedures. The anaesthetic sequence described by Kay4 is suitable for laparoscopy and more major surgery and was used as a basis for comparison. We had noted previously the marked hypertensive response to tracheal intubation, so on this occasion we added alfentanil30 pg/kg a t induction 5 , 6 and excluded opioid prernedication. The aims were to compare the two techniques in terms of haemodynamic stability after induction, speed of recovery and incidence of complications after operation. MethodsPatient group. Eighty female patients scheduled for laparoscopy were included in the study. All were ASA grades 1-2 and aged between 1&45 years. None was taking any drugs likely to modify response to the agents used and all gave informed consent to the study.Procedure. All patients received temazepam 20 mg orally 2 hours before operation. An ECG monitor was connected and a cannula placed in a forearm vein on arrival in the anaesthetic room. Arterial pressure was observed using a Dinamap 846 noninvasive blood pressure monitor. Baseline values of blood pressure and pulse rate were recorded before induction and subsequently every 60 seconds for 10 minutes, and at I-3-minute intervals thereafter.The patients were allocated randomly to two groups at the pre-operative visit. Group 1 received alfentanil 10 pg/kg, propofol 2 mg/kg and vecuronium 0.1 mg/kg at induction. Anaesthesia was maintained with a mixture of propofol 200 mg and alfentanil 1 mg at six times the induction dose in ml/hour delivered by a syringe pump (Imed 800). Group 2 were given alfentanil 30 pg/kg, ketamine 1 mg/kg, midazolam 0.07 mg/kg and vecuronium 0.1 mg/kg a t induction. Maintenance was provided by a continuous infusion of ketamine 200 mg and midazolam 5 mg made up to 50 ml with NaCl and delivered by syringe pump at a rate, equal to half the patient's body weight in kg, in ml/hour.Correspondence should be addressed t o Brigadier J. Restall.
The effects of temazepam 20 mg and placebo were compared for premedication in patients anaesthetized with propofol and alfentanil and undergoing day surgery. Temazepam 20 mg significantly reduced preoperative anxiety and increased recovery time. A series of computerized cognitive tasks revealed significant deficits in attention and memory following anaesthesia, which were increased in range and magnitude by temazepam, which were apparent 30 min after surgery and had largely, but not completely, recovered at 4 h. This study has demonstrated that computerized cognitive testing can identify a wider profile of impairments produced by temazepam than has been found in previous work using non-computerized techniques.
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