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A SIMPLE ANAESTHETIC EXPIRATION FLUE AND ITS FUNCTIONAL ANALYSIS
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CORRESPONDENCE
2 cm and that the flow rate should not exceed 60 L/min. With such a system at flow rates up to 25 L/min, the Sir,—An editorial in Anaesthesia (1972, 27, 1) commenting increase in pressure was found to be less than 0.5 cm on the hazards of prolonged or repeated exposure to anaes- of HiO. Readily available standard corrugated tubing thetic agents suggests that some means of extracting ex- satisfies the above criteria. Extraction efficiency. The extraction efficiency of the haled anaesthetic gases from the theatre should be used. For more than six months we and our colleagues have device was tested using a Hook and Tucker halnthan^ been using such a device which is simple and inexpensive analyser in the laboratory and in the theatre and was to make but is able to reduce the concentration of found to be satisfactory. Typical readings in the theatre anaesthetic vapour round a Heidbrink "BOC" valve to showed that at a flow rate of 8 l./min with the Fluotec at 1% the concentration of halothane in the tubing virtually zero. between the reservoir bag and the expiratory valve was 0.9% and at the expiratory valve without the device it Description of the device. The device is made from the disposable container of was 0.4%. With the expiration flue in position no a 20-ml Brunswick syringe. The bottom of the barrel of measurable reading was obtained on the analyser, whereas the container is cut off about 1 cm from its end and the at the end of the tubing of the flue it was 0.8%. We wish to thank Mrs V. M. Murchison of the top is cut through below the bulbous end (with a fine hack-saw blade) at a level so that the cut surface of the Medical Illustration Department for the photograph. bulbous end makes a flush fit with the expiratory valve. W. SNIPER The centre of the cap is removed at the level of the A. G. MURCHISON inner flange, using a strong scalpel, and the bottom of Glasgow, Scotland the barrel is inserted through the hole so formed. This produces a tight fit which can be made airtight by fusing the barrel to the flange. The method of construction is PRE-STRETCHED CUFFS ON TRACHEOSTOMY TUBES shown in the photograph. An appropriate length of Sir,—The reduction of tracheal damage by the pretubing is attached to the other end of the barrel. stretching of inflatable cuffs on endotracheal and tracheostomy tubes is well documented (Geffin and Pontoppidan, 1969). We wish to report a hazard which arose as a result of pre-stretching the cuff on a tracheostomy tube. The patient, a 56-year-old man, required prolonged ventilation following a road traffic accident. An elective tracheostomy was performed and a 36 F.G. Portex tracheostomy tube, with pre-stretched cuff, inserted. Postoperatively reduced movement and an expiratory wheeze developed on the right side of the chesL Chest X-ray showed right-sided hyperinflation. Cuff deflation considerably relieved the symptoms. The tube was therefore changed and the patient's condition immediately improved. The original tube was then examined and inflated in the barrel of a 20-ml syringe. It was then observed that the cuff herniated posteriorly and to the right, partially occluding and displacing the lumen of the tube to the left. It would therefore appear that the patient's condition The advantage of our device is that, if desired, the was caused by the partial occlusion of the right main bulbous end can be left attached to the expiratory valve bronchus by the pre-stretched tracheal cuff, resulting in without interfering with the function or adjustment of impaired right lung deflation. the latter and, when extraction is required, the cap and It is worth recording that the pre-stretching was done barrel with tube attached can be fitted immediately. In rapidly, as the original tube selected at operation was addition, there are no moving parts which can go wrong. too large to fit the trachea and a smaller tube was hastily prepared. This highlights the need for careful preparation Functional analysis. of pre-stretched cuffs if they are required. Expiratory "resistance". With the object in mind of J. G. WANDLESS finding the optimum length and diameter of tube attached F. M. EMERY to the expiratory flue which would produce the least J. EVANS increase in expiratory pressure, tubes of varying lengths R. J. E. FOLEY and diameters were attached to a gas supply of varying London flow rates and the pressure changes at the patient end REFERENCE of the apparatus measured. To keep the increase in expiratory pressure below Geffin, B., and Pontoppidan, H. (1969). Reduction of tracheal damage by the pre-stretching of inflatable "3 cm of HsO", it was found that the tubing should not cuffs. Anestheswlogy, 31, 462. exceed 5 metres in length, with a diameter more than A SIMPLE ANAESTHETIC EXPIRATION FLUE AND ITS FUNCTIONAL ANALYSIS
Primed In Great Britain by John Sberrau & Son Ltd, Puk Road, Aftrindmm, Cbotdtc WA14 5QQ
Downloaded from http://bja.oxfordjournals.org/ at Yale University on July 7, 2015
U
CORRESPONDENCE
2 cm and that the flow rate should not exceed 60 L/min. With such a system at flow rates up to 25 L/min, the Sir,—An editorial in Anaesthesia (1972, 27, 1) commenting increase in pressure was found to be less than 0.5 cm on the hazards of prolonged or repeated exposure to anaes- of HiO. Readily available standard corrugated tubing thetic agents suggests that some means of extracting ex- satisfies the above criteria. Extraction efficiency. The extraction efficiency of the haled anaesthetic gases from the theatre should be used. For more than six months we and our colleagues have device was tested using a Hook and Tucker halnthan^ been using such a device which is simple and inexpensive analyser in the laboratory and in the theatre and was to make but is able to reduce the concentration of found to be satisfactory. Typical readings in the theatre anaesthetic vapour round a Heidbrink "BOC" valve to showed that at a flow rate of 8 l./min with the Fluotec at 1% the concentration of halothane in the tubing virtually zero. between the reservoir bag and the expiratory valve was 0.9% and at the expiratory valve without the device it Description of the device. The device is made from the disposable container of was 0.4%. With the expiration flue in position no a 20-ml Brunswick syringe. The bottom of the barrel of measurable reading was obtained on the analyser, whereas the container is cut off about 1 cm from its end and the at the end of the tubing of the flue it was 0.8%. We wish to thank Mrs V. M. Murchison of the top is cut through below the bulbous end (with a fine hack-saw blade) at a level so that the cut surface of the Medical Illustration Department for the photograph. bulbous end makes a flush fit with the expiratory valve. W. SNIPER The centre of the cap is removed at the level of the A. G. MURCHISON inner flange, using a strong scalpel, and the bottom of Glasgow, Scotland the barrel is inserted through the hole so formed. This produces a tight fit which can be made airtight by fusing the barrel to the flange. The method of construction is PRE-STRETCHED CUFFS ON TRACHEOSTOMY TUBES shown in the photograph. An appropriate length of Sir,—The reduction of tracheal damage by the pretubing is attached to the other end of the barrel. stretching of inflatable cuffs on endotracheal and tracheostomy tubes is well documented (Geffin and Pontoppidan, 1969). We wish to report a hazard which arose as a result of pre-stretching the cuff on a tracheostomy tube. The patient, a 56-year-old man, required prolonged ventilation following a road traffic accident. An elective tracheostomy was performed and a 36 F.G. Portex tracheostomy tube, with pre-stretched cuff, inserted. Postoperatively reduced movement and an expiratory wheeze developed on the right side of the chesL Chest X-ray showed right-sided hyperinflation. Cuff deflation considerably relieved the symptoms. The tube was therefore changed and the patient's condition immediately improved. The original tube was then examined and inflated in the barrel of a 20-ml syringe. It was then observed that the cuff herniated posteriorly and to the right, partially occluding and displacing the lumen of the tube to the left. It would therefore appear that the patient's condition The advantage of our device is that, if desired, the was caused by the partial occlusion of the right main bulbous end can be left attached to the expiratory valve bronchus by the pre-stretched tracheal cuff, resulting in without interfering with the function or adjustment of impaired right lung deflation. the latter and, when extraction is required, the cap and It is worth recording that the pre-stretching was done barrel with tube attached can be fitted immediately. In rapidly, as the original tube selected at operation was addition, there are no moving parts which can go wrong. too large to fit the trachea and a smaller tube was hastily prepared. This highlights the need for careful preparation Functional analysis. of pre-stretched cuffs if they are required. Expiratory "resistance". With the object in mind of J. G. WANDLESS finding the optimum length and diameter of tube attached F. M. EMERY to the expiratory flue which would produce the least J. EVANS increase in expiratory pressure, tubes of varying lengths R. J. E. FOLEY and diameters were attached to a gas supply of varying London flow rates and the pressure changes at the patient end REFERENCE of the apparatus measured. To keep the increase in expiratory pressure below Geffin, B., and Pontoppidan, H. (1969). Reduction of tracheal damage by the pre-stretching of inflatable "3 cm of HsO", it was found that the tubing should not cuffs. Anestheswlogy, 31, 462. exceed 5 metres in length, with a diameter more than A SIMPLE ANAESTHETIC EXPIRATION FLUE AND ITS FUNCTIONAL ANALYSIS
Primed In Great Britain by John Sberrau & Son Ltd, Puk Road, Aftrindmm, Cbotdtc WA14 5QQ
Downloaded from http://bja.oxfordjournals.org/ at Yale University on July 7, 2015
U