Corresponcdence of hospital, their contract, their committee experience, age, sex, etc. clearly influence their attitude. The matter was fully discussed in a Report of a Working Party under the chairmanship of Dr J.S. Inkster which was sent to members in September 1974. Incidentally, one of the three continuing elected members from London was never a Council nominee and was elected in a contested ballot in
291
1975. The eliminated candidates all worked well away from London. The Association of Anaesthetists M.D. VICKERS of Great Britain and Ireland Honorary Secretary
(In the November 1976 election there was a 'clean sweep' for the provinces. Two of the 6 Council nominees were not elected. One of these was from London and one from the provinces-Editor.)
Jet ventilation for microlaryngoscopy-a modification Many techniques have been described for ventilating patients undergoing microlaryngoscopy using a jet of oxygen or nitrous oxide-oxygen mixture through an intratracheal catheter placed ~rotracheally'-~or nasotra~heally.~ We would like to communicate the use of a modification of a readily available disposable bronchoscopy suction cannula (Argyle 12FG) as a jetting tube, which has proved satisfactory in clinical practice. The semirigid bronchoscopy suction cannula with an internal diameter of 2.5 mm (12FG) is cut to a length of 25 cm and the distal end flared to form a small flange by pressing it on a flat metal surface after mild heating over a spirit lamp. The proximal bulbous end is easily connected by high pressure hosing to a wall outlet of oxygen (414 kPa*) with an on-off button and an adjustable reducing valve interposed in between. The driving pressure of the jet is varied by manipulating the adjustable reducing valve. In all cases, and especially in the presence of any degree of laryngeal obstruction detected pre-operatively or assessed intra-operatively, the minimal driving pressure of the jet necessary to obtain an adequate amount of chest movement should be used; this is accomplished by gradually increasing the driving pressure by 34.5 kPa increments, starting with 138 kPa and going up to 414 kPa if necessary. Maximal plateau airway pressures recorded beyond the cannula from the lumen of an 11 mm armoured endotracheal tube in an experimental set-up with a Drliger model lung and a Validyne DP15 transducer were as follows: Driving pressure Maximal airway pressure @Pa) (cm H20)t 138 16 207 32 276 40 345 44 414 47
* 1 H a = 0.01 Bar = 0.145 psi. t 1 cmH,O = 0.0981 kPa.
We feel that this technique provides excellent operating conditions for the surgeon while at the same time providing adequate oxygenation and ventilation, with little likelihood of soiling of the trachea because of outflow of gas during inspiration and expiration. Careful pre-operative and intraoperative assessment of laryngeal obstruction, the use of the correct driving pressure together with constant monitoring of chest movement and adequate anaesthesia and paralysis at all times contribute to its success. Department of Anaesthesia & Intensive Care, Royal Adelaide Hospital, V.S. IYER Adelaide, S.A . 5000, South Australia D.G. FENWICK References I . EL-NAGGAR, M., KEH,E., STEMMERS, A. & COLLINS,
2. 3.
4. 5.
V.J. (1974) Jet ventilation for microlaryngoscopic procedures. Anesthesia and Analgesia; Current Researches, 53, 797. SMITH,R.B., BEBINSKI, M. & PETRUSACK, J. (1974) A method of ventilating patients during laryngosscopy. Laryngoscope, 85, 553. CARDEN, E. & CRUTCHFIELD, W. (1973) Anaesthesia for microsurgery of the larynx. Canadian Anaesthetists' Society Journal, 20, 378. DAGHLIAN, B.D. (1976) A useful tube for anaesthesia during laryngeal microsurgery. British Journal of Anaesthesia, 48, 607. SPOEREL, W.E. & GREENWAY, R.E. (1973)Techniques of ventilation during endolaryngeal surgery under general anaesthesia. Canadian Anaesthetists' Society Journal, 20, 369.
291
1975. The eliminated candidates all worked well away from London. The Association of Anaesthetists M.D. VICKERS of Great Britain and Ireland Honorary Secretary
(In the November 1976 election there was a 'clean sweep' for the provinces. Two of the 6 Council nominees were not elected. One of these was from London and one from the provinces-Editor.)
Jet ventilation for microlaryngoscopy-a modification Many techniques have been described for ventilating patients undergoing microlaryngoscopy using a jet of oxygen or nitrous oxide-oxygen mixture through an intratracheal catheter placed ~rotracheally'-~or nasotra~heally.~ We would like to communicate the use of a modification of a readily available disposable bronchoscopy suction cannula (Argyle 12FG) as a jetting tube, which has proved satisfactory in clinical practice. The semirigid bronchoscopy suction cannula with an internal diameter of 2.5 mm (12FG) is cut to a length of 25 cm and the distal end flared to form a small flange by pressing it on a flat metal surface after mild heating over a spirit lamp. The proximal bulbous end is easily connected by high pressure hosing to a wall outlet of oxygen (414 kPa*) with an on-off button and an adjustable reducing valve interposed in between. The driving pressure of the jet is varied by manipulating the adjustable reducing valve. In all cases, and especially in the presence of any degree of laryngeal obstruction detected pre-operatively or assessed intra-operatively, the minimal driving pressure of the jet necessary to obtain an adequate amount of chest movement should be used; this is accomplished by gradually increasing the driving pressure by 34.5 kPa increments, starting with 138 kPa and going up to 414 kPa if necessary. Maximal plateau airway pressures recorded beyond the cannula from the lumen of an 11 mm armoured endotracheal tube in an experimental set-up with a Drliger model lung and a Validyne DP15 transducer were as follows: Driving pressure Maximal airway pressure @Pa) (cm H20)t 138 16 207 32 276 40 345 44 414 47
* 1 H a = 0.01 Bar = 0.145 psi. t 1 cmH,O = 0.0981 kPa.
We feel that this technique provides excellent operating conditions for the surgeon while at the same time providing adequate oxygenation and ventilation, with little likelihood of soiling of the trachea because of outflow of gas during inspiration and expiration. Careful pre-operative and intraoperative assessment of laryngeal obstruction, the use of the correct driving pressure together with constant monitoring of chest movement and adequate anaesthesia and paralysis at all times contribute to its success. Department of Anaesthesia & Intensive Care, Royal Adelaide Hospital, V.S. IYER Adelaide, S.A . 5000, South Australia D.G. FENWICK References I . EL-NAGGAR, M., KEH,E., STEMMERS, A. & COLLINS,
2. 3.
4. 5.
V.J. (1974) Jet ventilation for microlaryngoscopic procedures. Anesthesia and Analgesia; Current Researches, 53, 797. SMITH,R.B., BEBINSKI, M. & PETRUSACK, J. (1974) A method of ventilating patients during laryngosscopy. Laryngoscope, 85, 553. CARDEN, E. & CRUTCHFIELD, W. (1973) Anaesthesia for microsurgery of the larynx. Canadian Anaesthetists' Society Journal, 20, 378. DAGHLIAN, B.D. (1976) A useful tube for anaesthesia during laryngeal microsurgery. British Journal of Anaesthesia, 48, 607. SPOEREL, W.E. & GREENWAY, R.E. (1973)Techniques of ventilation during endolaryngeal surgery under general anaesthesia. Canadian Anaesthetists' Society Journal, 20, 369.
