Failure of nitrous oxide and oxygen pin-indexing

Images

Cameco anaesthetic ventilator with a modified Mapleson D circuit

A modified Mapleson D circuit has been used in connection with a Cameco anaesthetic ventilator during neuroradiological procedures in general anaesthesia. In order to increase mobility of the patient, two or three lengths of corrugated rubber tubing were used to connect the patient to the ventilator. Blood gas analysis was carried out in 20 patients after ventilation to steady state with both circuits. The respiratory minute volume and fresh gas flow were preset in Bain's (Bain & Spoerel 1975) predictions. No significant difference could be detected in respect to Paco2 or Po2, whether 2 or 3 lengths of tubing were used. Mean values of Paco2 were higher compared with the results of Bain (0.37 kPa s.d. 0.50). It is concluded that this system gives maximum mobility of the patient during the radiological procedure and offers reliable adjustment of Paco2, even in patients with apparent increase of intracranial pressure.

[Functional evaluation of "tekatest", a test equipment for halothane-vaporizers (author's transl)]

The results of investigations on the reliability of a commericially available test equipment for anaesthetic vaporizers based on the Rotameter principle (s.c. "Tekatest") are reported. In prototype devices scattered differences up to 27% between the results obtained by the Tekatest and those derived from gas chromatography and mass-spectrometry were noted; in a somewhat improved version an unidirectional error of about 24% became evident. Up to now, therefore, this test equipment cannot be recommended for recalibration of vaporizers in clinical use.

[A simple modification for the electrochemical oxygen analyzer to improve accuracy during prolonged closed system anaesthesia (author's transl)]

A simple modification of the condenser used with the electro-chemical oxygen analyzer (Dräger BioMarine OA202 R) consists of filling the distal chamber with hygroscopic silicagel. This prevents condensation of water vapour on the sensor thus allowing the accuracy during prolonged closed system anaesthesia to remain nearly unaffected (fade less than 0.5%/h).

Anaesthetic experiences in orthodontic surgery

The anaesthetic experiences and problems have been analysed, based on 100 orthognathic operations. The material includes all kinds of operations; operating time was about 4 hours, except for 8 very extensive procedures, lasting 6--7 hours. The importance of adequate premedication is emphasized. The use of nasal drops for decongestion is especially highly recommended for the prevention of bleeding during nasal intubation. An armoured nasal tube is always used; however, special care must be taken to detect leaks on the cuff. On four occasions the tubes had to be changed because of leaks in the cuff. The most annoying complication was tachycardia, due to: insufficient premedication, insufficient analgesics during operation, or the use of hypotensive drugs. Blood loss was clearly diminished by controlled hypotension. Postoperative vomiting was prevented by the use of a nasogastric tube for the first 6--8 hours. Major complications were not encountered.

[Prevention of intra, and postoperative complications. Capabilities of the anesthesist]

Prevention of intra- and postoperative complications is one of the main tasks of the anesthesiologist. It is achieved by avoidance of specific anesthesiological dangers and mistakes and by adjustment of anesthetic techniques to the course of operation. Recognition and consideration of preexisting diseases as possible causes of complications and appropriate preoperative measures are the responsibility of the surgical-anesthesiological team. Depending on the given situation and the risk state of the patient during and after operation, special anesthetic procedures may be necessary.

Anaesthetic machine hazards

The anaesthetist is ultimately responsible for ensuring that the machine used for a particular anaesthetic is in a safe condition before the procedure is commenced. He can only do this if he understands how the machine operates, and has established for himself a checking procedure which will uncover potentially lethal faults in the apparatus. The importance of a systematic and thorough check cannot be overemphasized. Continuing monitoring of the machine and the patient during the anaesthetic is mandatory.

The flomasta. A new anaesthetic ventilator

A new ventilator for use during anaesthesia is described. It operates as a minute-volume divider and derives its power from the energy stored in a distended reservoir bag. The unit is autoclavable, suitable for use with explosive anaesthetics and has a rational control system which avoids many of the hazards associated with other ventilators when the mode of ventilation is changed. The nature of the inspired gas mixture is known accurately because the internal volume of the ventilator is small and the system is non-rebreathing. The design of the exhaust system facilitates ventilation monitoring, the use of positive end-expiratory pressure and connection to ducted pollution-control systems.

[The paedi-circle. A new paediatric anaesthesia system (author's transl)]

A new anaesthesia system for infants and small children has been designed. The system--consisting of clinically proven - is easy to handle and to be exchanged; the components problem of anaesthesia gas exhausting (filters or central suction system) has been simplified, compared to the previous fresh gas system (Kuhn or Rees).

Problems in general anaesthesia. Dental

Administration of general anaesthetics in the dentist's surgery is widely practised in Australia. There is considerable demand for this service, and those doctors who supply it fill a very real need. Where medical practitioners fail to supply this service, dentists are forced to use sedation techniques and may be tempted to push these beyond the limits of safety.

Problems in general anaesthesia. Paediatrics

Many general practitioners are involved in anaesthesia and consequently, from time to time are called upon to anaesthetize children. This paper is aimed at provideing information on the differences between adults and children, and indicating how recognition of these differences will prevent many of the problems that may occur in paediatric general anaesthesia.