Anaesth. Tntens. Care (1979), 7, 258
A NEW TUBE FOR MICROLARYNGEAL SURGERY BRUCE BENJAMIN* AND DAVID GRONOW**
Royal Alexandra Hospital for Children and Sydney Hospital, Sydney SUMMARY
A technique of anaesthesia for micro laryngeal surgery is described lItilizing a new catheter and the venturi jet injector. Access and exposure for the surgeon are excellent and the laser can be used without special precalltions. The central position and lack of movement of the distal end of the tube in the trachea prevent the potential complication of rupture of the trachea or of a bronchus. Microlaryngeal surgery is firmly established as part of modern laryngology. It offers the advantages of variable magnification, brilliant illumination, binocular vision and use of a self-retaining and self-supporting laryngoscope. Thus micro laryngoscopy allows thorough examination for accurate diagnosis and precise surgical treatment, more recently with the carbon dioxide laser. Nevertheless there are some disadvantages. A general anaesthetic is necessary and techniques which require a standard endotracheal tube do not allow adequate exposure for the surgical procedure; the presence of an endotracheal tube obstructs the surgeon's view. Anaesthetic methods without a tube are preferable for the surgeon but not so acceptable to the anaesthetist as there may not be sufficient control of ventilation. Anaesthesia for examination or manipulation within the larynx has exercised the ingenuity of anaesthetists for years and new techniques are regularly proposed, the more so since the advent of microsurgery of the larynx has posed new problems. The techniques which have been used * O.B.E.. M.B.. B.S.. D.L.O., F.R.A.C.S. Lecturer. in Diseases of the Ear. Nose and Throat. Sydney Untversily. Honorary E.N .T. Surgeon. Sydney Hospital and Royal Alexandra Hospital for Children. ** M.B., B.S., F.F.A.R.A.C.S. Staff Anaesthetist. Sydney Hospital. Address for reprints: Or. B. Benjamin. Sydney Hospital. Mac4uarie Street. Sydney. N.S.W. 2(X)O, Australia.
generally come into one or more of the following groupS: No endotracheal tube with controlled respiration using an external chest respirator such as the cuirass; spontaneous respiration with insufflation of anaesthetic gases (Lines 1973); a venturi jet used proximally in the lumen of the laryngoscope (Norton 1976, Vourch et al. 1977, Sanders 1967). A standard endotracheal tube used either with the patient paralysed or with the patient breathing spontaneously. A modified endotracheal tube. Use of a small diameter standard endotracheal tube; a catheter with high flow oxygen insufflation; the 'Pollard' tube (Pollard 1968), the 'Carden' tube (Carden and Vest 1974) or a catheter with a jet (EI-Nagger et al. 1974, Carden and Ferguson 1973, Tobias et al. 1974 ). Various transtracheal techniques (Spoerel, et al. 197 I) have been used and lastly anaesthesia may be delivered via a tracheotomy. The requirements for laryngeal microsurgery include simplicity, rapid induction yet prompt recovery, an immobile and unobstructed operative field, no restriction on time, control of secretions, prevention of aspiration and safe use of the laser. These ideals must be compatible with maximum safety and minimum patient discomfort. AIlae\'lhesia and lntet1\i\'(' Care. Vol. VII. No. 3. August, 1979
MICROLARYNGEAL SURGERY
General anaesthesia with a muscle relaxant and maintenance of adequate pulmonary ventilation achieves these requirements when a peroral, translaryngeal, endotracheal catheter of small diameter is used to maintain adequate gaseous exchange. Because of difficulties which we had with various existing techniques we looked for a means of using the venturi jet with a small diameter tube which would be stable in the larynx and in the trachea. In particular we wished to avoid the potentially dangerous 'whip' effect seen with a long, free-lying catheter as each jet causes the distal end to lash about in the trachea. A mucosal tear or traumatic laceration might allow gas to be injected into the mediastinum with production of pneumothorax.
259
and ensure even distribution of gas. The tube is simple, cheap, sterile, easy to introduce and remove, cannot be kinked, is unobtrusive in the larynx, stable in the tracheal lumen, atraumatic and above all it appears to be safe. Access and visualization for the surgeon are excellent (Fig. 1). The adult tube is 4.0 mm in external diameter with a black mark 8 cm from its distal tip and the paediatric tube is 2.8 mm in external diameter with a similar mark 5 cm from its distal tip (Fig. 2). Both tubes are 35 cm long. The jet opening at the distal end is approximately 1.7 mm in internal diameter (equivalent to a 16 gauge needle). The tubes have been used extensively in the last two years and have been found satisfactory in over 100 adults and 100 children, with no complications attributable to the tube.
The 'Benjamin Jet Tube' The tube is made of fairly rigid plastic. It has a proximal Luer-lock connection. There are four soft plastic 'petals' at the distal end, designed to maintain it in a central position in the trachea, prevent trauma to the tracheal wall
FIGURE
Anaesthetic Technique The actual and potential problems for each case are discussed by the anaesthetist and the surgeon. Use of the tube is contraindicated in the presence of significant laryngeal obstruction.
I.-The paediatric tube in the posterior commissure of a 5 year old patient with laryngeal papillomata.
Anaesthesia alld IlItensi .. e Care, Vol. VII, No. 3, AUjiust, 1979
260
B. BENJAMIN AND D. GRONOW
FIGURE
FIGURE
2.-The adult and paediatric tubes.
3.-General view of the tube in use. The four plastic "petals" maintain the end of the tube in the mid-trachea. Anaesthesia and Intensive Care, Vol. Vll, No. 3, AI/gllst, 1979
MICROLARYNGEAL SURGERY
Preparation with papaveretum and scopolamine in appropriate dosage is given intramuscularly one hour pre-operatively. After pre-oxygenation, anaesthesia is induced with Althesin 60 ftl/kg. Test ventilation with a mask is performed to detect any airway obstruction, then suxamethonium is given for relaxation and intubation. In every case topical analgesia, lignocaine (up to 5 mg/kg) is applied to the epiglottis, larynx and trachea using a Cass needle (Cass and Waldie 1964). The jet tube is inserted and to ensure the expiratory phase a Guedel airway or a nasopharyngeal airway is placed. It is more convenient to use a nasopharyngeal airway as it can be left in situ throughout the whole procedure.
FIGURE
THE EXPIRATORY PHASE MUST BE UNIMPAIRED AT ALL TIMES. Proper placement of the tube is assessed visually, the black mark on the tube acting as a guide, so that the distal end of the tube is in the mid-trachea (Fig. 3). Ventilation of both lungs is checked by auscultation and the tube is fixed to the face by strapping. The tube normally sits in the posterior commissure of the larynx but it can easily be displaced and maintained anteriorly for access to posterior pathology. The proximal end of the tube is securely attached to the "bronchoflator" equipment (Komesaroff and McKie 1972 ) (Fig. 4). The eyes are always protected, with wet pads when the laser is in use.
4.-DetaiIed view of the tube in use.
Anaesthesia and Intensive Care, Vol. Vll, No. 3, AI/gust, 1979
261
H. BENJAMIN AND D. GRONOW
Maintenance of anaesthesia depends on the expected duration of the procedure; for short procedures intermittent doses of suxamethonium and Althesin are used; for long procedures (longer than 15 minutes) aIcuronium is used with intermittent doses of Althesin and fentanyl. In children sodium thiopentone has been used instead of AIthesin. The movement of the chest is the usual clinical guide to adequacy of ventilation. The base of the self-retaining laryngoscope holder should rest not on the chest, but on a table. In five random adult cases, blood gas analysis was performed to assess the performance of the tube. With prior consent of the patient, a radial artery cannula was inserted after performance of the AlIen's test (Alien 1929) and serial blood gas analysis was performed. In all cases adequate oxygenation and ventilation were achieved. On completion of the procedure the laryngoscope is withdrawn, the jet tube is left in situ and a Guedel airway is re-inserted, or the nasopharyngeal airway left in place. Ventilation is continued via the jet tube until the patient is ready for extubation, neostigmine and atropine being used when appropriate. Oxygen supplementation is continued in a recovery ward. DISCUSSION
All anaesthetic techniques utilizing the venturi jet ventilation system have certain disadvantages. The jet blast can rupture the trachea or a bronchus (Carden and Crutchfield 1973, Clarkson and Davies 1978) and some jetting systems have been discarded because of this hazard. The tube we have described prevents this potential complication. The four soft plastic petals stabilize the tube firmly in the centre of the tracheal lumen and the end cannot impinge on the tracheal mucosa. The central position of the tube and the lack of movement during ventilation have been repeatedly confirmed by direct examination with a bronchoscopic telescope (Fig. 5). Jet ventilation in the trachea must not be used when the expiratory phase is unsatisfactory. Simple use of a Guedel airway before and after the laryngoscope is in place, or even better, a nasopharyngeal tube left in sitlt throughout the procedure will prevent oropharyngeal obstruction. Expiratory obstruction may also be due to a large, pre-existing
lesion in the larynx, for example in an adult with advanced malignancy or in a child having the first endoscopic examination to clear a large mass of papilloma. Where obstructive laryngeal pathology is suspected the endoscopist himself should assess the nature and extent of the lesion before any relaxant is given and the jet tube used. In an occasional patient there may be a more serious degree of obstruction than was expected and a suitable size of standard endotracheal tube can then be used. With these exceptions the technique is suitable for all patients over the age of three years. The injector jet technique is capable of maintaining satisfactory conditions for long periods and blood gases have been shown to be satisfactory (Spoerel and Greenway 1973). With some techniques (Norton 1976, Vourch et al. 1977) the venturi injector jet is used in the proximal lumen of the laryngoscope and the blast of gas produces unwanted vocal cord movement, drying of the mucosa of the larynx and there is a chance of foreign particulate matter, for example papilloma or blood clot passing into the tracheobronchial tree. None of these problems occur with the tube we have described. Compared to some other tubes designed for microlaryngoscopy anaesthesia, this new tube is easy to insert and there is no likelihood of kinking or of obstruction due to pressure. From the surgeon's point of view there is
FI(;URE
5.-The distal end of the tube remains stahle in the centre of the trachea.
AlllleHJu-'.\ia allt! Jnll!lnil'l' Ctlre,
Fol. 1'11, No. 3,
AllglHt,
1979
MICROLARYNGEAL SURGERY
excellent access to an immobile operative field, there is no limitation on time and attention need not be directed to or distracted by the method of anaesthesia. The tube is especially suitable for laser surgery in the larynx. The ability to easily position the small diameter tube in the anterior or posterior larynx means the laser beam may be used at a safe distance from the tube. It does not need protection with aluminium foil as has been suggested for other tubes. The tube is inexpensive and disposable being produced in a gamma-radiated plastic pack for single use only.
ACKNOWLEDGEMENTS
The authors wish to thank their colleagues in the Departments of Anaesthesia at both Sydney Hospital and at the Royal Alexandra Hospital for Children. Technical assistance to manufacture the tube was given by Tuta Laboratories (Australia) Pty. Ltd, Sydney, from whom supplies may be obtained.
REFERENCES
Alien, E. V. (1929): "Thromboangeitis Obliterans. Method of diagnosis of chronic occlusive arterial lesions distal to the wrist with illustrative cases", Amer. J. Med. Sc., 178, 237. Carden, E., and Crutch field, W. (1973): "Anaesthesia for Microsurgery of the Larynx (a new method)", Can ad. Anaesth. Soc. J., 20, 3, 378.
Anaesthesia and Illtellsive Care, Vol. Vll, No 3, August, 1979
263
Carden, E., and Ferguson, G. B. (1973): "A new technique for microlaryngeal surgery in infants", Laryngoscope, 83, 691. Carden, E., and Vest, H. R. (1974): "Further Advances in Anaesthetic Techniques for Microlaryngeal Surgery", Anaesth. Ana/g., 53, 584. Cass, N. M., and Waldie, I. A (1964): "A robust reliable throat spray", Brit. Anaesth., 36, 61. Clarkson, W. B., and Davies, J. R. (1978): "Anaesthesia for Carinal Resection", Anaesthesia, 33, 815. El-Nagger, M., Keh, E., Stemmers, A, and Coli ins, V. J. (1974): "Jet ventilation for microlaryngoscopic procedures. A further simplified technique", Anaesth. Analg., 53, 794. Komesaroff, D., and McKie, B. (1972): "The Bronchoflator. A new technique for bronchoscopy under general anaesthesia", Brit. J. Anaesth., 44, 1057. Lines, V. (1973): "Anaesthesia for Laryngoscopy and Microlaryngeal Surgery in Children", Anaesth. [ntens. Care, 1, 507. Norton, M. L. (1976): "Endotracheal Intubation and Venturi (jet) Ventilation for Laser Microsurgery of the Larynx", Annals of Otology, 85. 656. Pollard, B. J. (1968): "Anaesthesia for Laryngeal Microsurgery", Anaesthesia, 23, 534. Sanders, R. D. (1967): "Two ventilating attachments for bronchoscopes", Delaware Medical Journal, 39, 170. Spoerel, W. E., and Greenway, R. E. (1973): "Technique of ventilation during Endolaryngeal Surgery under general anaesthesia", Can ad. Anaesth. Soc. J., 20. 369. Spoerel, W. E., Narayanan, P. S., and Singh, N. P. (1971): "Transtracheal ventilation", Brit. J. Anaesth., 43, 932. Tobias, M. A, Nassar, W. Y., and Richards, D. C. (1977): "Naso-tracheal jet ventilation for microlaryngeal procedures", Anaesthesia, 32, 359. Vourch, G., Freche, G., and Tran Ban Hui, I. H. P. (1977): "Suspension laryngoscopy under general anaesthesia. A technique using an injector", Anaesthesia, 32, 803.
A NEW TUBE FOR MICROLARYNGEAL SURGERY BRUCE BENJAMIN* AND DAVID GRONOW**
Royal Alexandra Hospital for Children and Sydney Hospital, Sydney SUMMARY
A technique of anaesthesia for micro laryngeal surgery is described lItilizing a new catheter and the venturi jet injector. Access and exposure for the surgeon are excellent and the laser can be used without special precalltions. The central position and lack of movement of the distal end of the tube in the trachea prevent the potential complication of rupture of the trachea or of a bronchus. Microlaryngeal surgery is firmly established as part of modern laryngology. It offers the advantages of variable magnification, brilliant illumination, binocular vision and use of a self-retaining and self-supporting laryngoscope. Thus micro laryngoscopy allows thorough examination for accurate diagnosis and precise surgical treatment, more recently with the carbon dioxide laser. Nevertheless there are some disadvantages. A general anaesthetic is necessary and techniques which require a standard endotracheal tube do not allow adequate exposure for the surgical procedure; the presence of an endotracheal tube obstructs the surgeon's view. Anaesthetic methods without a tube are preferable for the surgeon but not so acceptable to the anaesthetist as there may not be sufficient control of ventilation. Anaesthesia for examination or manipulation within the larynx has exercised the ingenuity of anaesthetists for years and new techniques are regularly proposed, the more so since the advent of microsurgery of the larynx has posed new problems. The techniques which have been used * O.B.E.. M.B.. B.S.. D.L.O., F.R.A.C.S. Lecturer. in Diseases of the Ear. Nose and Throat. Sydney Untversily. Honorary E.N .T. Surgeon. Sydney Hospital and Royal Alexandra Hospital for Children. ** M.B., B.S., F.F.A.R.A.C.S. Staff Anaesthetist. Sydney Hospital. Address for reprints: Or. B. Benjamin. Sydney Hospital. Mac4uarie Street. Sydney. N.S.W. 2(X)O, Australia.
generally come into one or more of the following groupS: No endotracheal tube with controlled respiration using an external chest respirator such as the cuirass; spontaneous respiration with insufflation of anaesthetic gases (Lines 1973); a venturi jet used proximally in the lumen of the laryngoscope (Norton 1976, Vourch et al. 1977, Sanders 1967). A standard endotracheal tube used either with the patient paralysed or with the patient breathing spontaneously. A modified endotracheal tube. Use of a small diameter standard endotracheal tube; a catheter with high flow oxygen insufflation; the 'Pollard' tube (Pollard 1968), the 'Carden' tube (Carden and Vest 1974) or a catheter with a jet (EI-Nagger et al. 1974, Carden and Ferguson 1973, Tobias et al. 1974 ). Various transtracheal techniques (Spoerel, et al. 197 I) have been used and lastly anaesthesia may be delivered via a tracheotomy. The requirements for laryngeal microsurgery include simplicity, rapid induction yet prompt recovery, an immobile and unobstructed operative field, no restriction on time, control of secretions, prevention of aspiration and safe use of the laser. These ideals must be compatible with maximum safety and minimum patient discomfort. AIlae\'lhesia and lntet1\i\'(' Care. Vol. VII. No. 3. August, 1979
MICROLARYNGEAL SURGERY
General anaesthesia with a muscle relaxant and maintenance of adequate pulmonary ventilation achieves these requirements when a peroral, translaryngeal, endotracheal catheter of small diameter is used to maintain adequate gaseous exchange. Because of difficulties which we had with various existing techniques we looked for a means of using the venturi jet with a small diameter tube which would be stable in the larynx and in the trachea. In particular we wished to avoid the potentially dangerous 'whip' effect seen with a long, free-lying catheter as each jet causes the distal end to lash about in the trachea. A mucosal tear or traumatic laceration might allow gas to be injected into the mediastinum with production of pneumothorax.
259
and ensure even distribution of gas. The tube is simple, cheap, sterile, easy to introduce and remove, cannot be kinked, is unobtrusive in the larynx, stable in the tracheal lumen, atraumatic and above all it appears to be safe. Access and visualization for the surgeon are excellent (Fig. 1). The adult tube is 4.0 mm in external diameter with a black mark 8 cm from its distal tip and the paediatric tube is 2.8 mm in external diameter with a similar mark 5 cm from its distal tip (Fig. 2). Both tubes are 35 cm long. The jet opening at the distal end is approximately 1.7 mm in internal diameter (equivalent to a 16 gauge needle). The tubes have been used extensively in the last two years and have been found satisfactory in over 100 adults and 100 children, with no complications attributable to the tube.
The 'Benjamin Jet Tube' The tube is made of fairly rigid plastic. It has a proximal Luer-lock connection. There are four soft plastic 'petals' at the distal end, designed to maintain it in a central position in the trachea, prevent trauma to the tracheal wall
FIGURE
Anaesthetic Technique The actual and potential problems for each case are discussed by the anaesthetist and the surgeon. Use of the tube is contraindicated in the presence of significant laryngeal obstruction.
I.-The paediatric tube in the posterior commissure of a 5 year old patient with laryngeal papillomata.
Anaesthesia alld IlItensi .. e Care, Vol. VII, No. 3, AUjiust, 1979
260
B. BENJAMIN AND D. GRONOW
FIGURE
FIGURE
2.-The adult and paediatric tubes.
3.-General view of the tube in use. The four plastic "petals" maintain the end of the tube in the mid-trachea. Anaesthesia and Intensive Care, Vol. Vll, No. 3, AI/gllst, 1979
MICROLARYNGEAL SURGERY
Preparation with papaveretum and scopolamine in appropriate dosage is given intramuscularly one hour pre-operatively. After pre-oxygenation, anaesthesia is induced with Althesin 60 ftl/kg. Test ventilation with a mask is performed to detect any airway obstruction, then suxamethonium is given for relaxation and intubation. In every case topical analgesia, lignocaine (up to 5 mg/kg) is applied to the epiglottis, larynx and trachea using a Cass needle (Cass and Waldie 1964). The jet tube is inserted and to ensure the expiratory phase a Guedel airway or a nasopharyngeal airway is placed. It is more convenient to use a nasopharyngeal airway as it can be left in situ throughout the whole procedure.
FIGURE
THE EXPIRATORY PHASE MUST BE UNIMPAIRED AT ALL TIMES. Proper placement of the tube is assessed visually, the black mark on the tube acting as a guide, so that the distal end of the tube is in the mid-trachea (Fig. 3). Ventilation of both lungs is checked by auscultation and the tube is fixed to the face by strapping. The tube normally sits in the posterior commissure of the larynx but it can easily be displaced and maintained anteriorly for access to posterior pathology. The proximal end of the tube is securely attached to the "bronchoflator" equipment (Komesaroff and McKie 1972 ) (Fig. 4). The eyes are always protected, with wet pads when the laser is in use.
4.-DetaiIed view of the tube in use.
Anaesthesia and Intensive Care, Vol. Vll, No. 3, AI/gust, 1979
261
H. BENJAMIN AND D. GRONOW
Maintenance of anaesthesia depends on the expected duration of the procedure; for short procedures intermittent doses of suxamethonium and Althesin are used; for long procedures (longer than 15 minutes) aIcuronium is used with intermittent doses of Althesin and fentanyl. In children sodium thiopentone has been used instead of AIthesin. The movement of the chest is the usual clinical guide to adequacy of ventilation. The base of the self-retaining laryngoscope holder should rest not on the chest, but on a table. In five random adult cases, blood gas analysis was performed to assess the performance of the tube. With prior consent of the patient, a radial artery cannula was inserted after performance of the AlIen's test (Alien 1929) and serial blood gas analysis was performed. In all cases adequate oxygenation and ventilation were achieved. On completion of the procedure the laryngoscope is withdrawn, the jet tube is left in situ and a Guedel airway is re-inserted, or the nasopharyngeal airway left in place. Ventilation is continued via the jet tube until the patient is ready for extubation, neostigmine and atropine being used when appropriate. Oxygen supplementation is continued in a recovery ward. DISCUSSION
All anaesthetic techniques utilizing the venturi jet ventilation system have certain disadvantages. The jet blast can rupture the trachea or a bronchus (Carden and Crutchfield 1973, Clarkson and Davies 1978) and some jetting systems have been discarded because of this hazard. The tube we have described prevents this potential complication. The four soft plastic petals stabilize the tube firmly in the centre of the tracheal lumen and the end cannot impinge on the tracheal mucosa. The central position of the tube and the lack of movement during ventilation have been repeatedly confirmed by direct examination with a bronchoscopic telescope (Fig. 5). Jet ventilation in the trachea must not be used when the expiratory phase is unsatisfactory. Simple use of a Guedel airway before and after the laryngoscope is in place, or even better, a nasopharyngeal tube left in sitlt throughout the procedure will prevent oropharyngeal obstruction. Expiratory obstruction may also be due to a large, pre-existing
lesion in the larynx, for example in an adult with advanced malignancy or in a child having the first endoscopic examination to clear a large mass of papilloma. Where obstructive laryngeal pathology is suspected the endoscopist himself should assess the nature and extent of the lesion before any relaxant is given and the jet tube used. In an occasional patient there may be a more serious degree of obstruction than was expected and a suitable size of standard endotracheal tube can then be used. With these exceptions the technique is suitable for all patients over the age of three years. The injector jet technique is capable of maintaining satisfactory conditions for long periods and blood gases have been shown to be satisfactory (Spoerel and Greenway 1973). With some techniques (Norton 1976, Vourch et al. 1977) the venturi injector jet is used in the proximal lumen of the laryngoscope and the blast of gas produces unwanted vocal cord movement, drying of the mucosa of the larynx and there is a chance of foreign particulate matter, for example papilloma or blood clot passing into the tracheobronchial tree. None of these problems occur with the tube we have described. Compared to some other tubes designed for microlaryngoscopy anaesthesia, this new tube is easy to insert and there is no likelihood of kinking or of obstruction due to pressure. From the surgeon's point of view there is
FI(;URE
5.-The distal end of the tube remains stahle in the centre of the trachea.
AlllleHJu-'.\ia allt! Jnll!lnil'l' Ctlre,
Fol. 1'11, No. 3,
AllglHt,
1979
MICROLARYNGEAL SURGERY
excellent access to an immobile operative field, there is no limitation on time and attention need not be directed to or distracted by the method of anaesthesia. The tube is especially suitable for laser surgery in the larynx. The ability to easily position the small diameter tube in the anterior or posterior larynx means the laser beam may be used at a safe distance from the tube. It does not need protection with aluminium foil as has been suggested for other tubes. The tube is inexpensive and disposable being produced in a gamma-radiated plastic pack for single use only.
ACKNOWLEDGEMENTS
The authors wish to thank their colleagues in the Departments of Anaesthesia at both Sydney Hospital and at the Royal Alexandra Hospital for Children. Technical assistance to manufacture the tube was given by Tuta Laboratories (Australia) Pty. Ltd, Sydney, from whom supplies may be obtained.
REFERENCES
Alien, E. V. (1929): "Thromboangeitis Obliterans. Method of diagnosis of chronic occlusive arterial lesions distal to the wrist with illustrative cases", Amer. J. Med. Sc., 178, 237. Carden, E., and Crutch field, W. (1973): "Anaesthesia for Microsurgery of the Larynx (a new method)", Can ad. Anaesth. Soc. J., 20, 3, 378.
Anaesthesia and Illtellsive Care, Vol. Vll, No 3, August, 1979
263
Carden, E., and Ferguson, G. B. (1973): "A new technique for microlaryngeal surgery in infants", Laryngoscope, 83, 691. Carden, E., and Vest, H. R. (1974): "Further Advances in Anaesthetic Techniques for Microlaryngeal Surgery", Anaesth. Ana/g., 53, 584. Cass, N. M., and Waldie, I. A (1964): "A robust reliable throat spray", Brit. Anaesth., 36, 61. Clarkson, W. B., and Davies, J. R. (1978): "Anaesthesia for Carinal Resection", Anaesthesia, 33, 815. El-Nagger, M., Keh, E., Stemmers, A, and Coli ins, V. J. (1974): "Jet ventilation for microlaryngoscopic procedures. A further simplified technique", Anaesth. Analg., 53, 794. Komesaroff, D., and McKie, B. (1972): "The Bronchoflator. A new technique for bronchoscopy under general anaesthesia", Brit. J. Anaesth., 44, 1057. Lines, V. (1973): "Anaesthesia for Laryngoscopy and Microlaryngeal Surgery in Children", Anaesth. [ntens. Care, 1, 507. Norton, M. L. (1976): "Endotracheal Intubation and Venturi (jet) Ventilation for Laser Microsurgery of the Larynx", Annals of Otology, 85. 656. Pollard, B. J. (1968): "Anaesthesia for Laryngeal Microsurgery", Anaesthesia, 23, 534. Sanders, R. D. (1967): "Two ventilating attachments for bronchoscopes", Delaware Medical Journal, 39, 170. Spoerel, W. E., and Greenway, R. E. (1973): "Technique of ventilation during Endolaryngeal Surgery under general anaesthesia", Can ad. Anaesth. Soc. J., 20. 369. Spoerel, W. E., Narayanan, P. S., and Singh, N. P. (1971): "Transtracheal ventilation", Brit. J. Anaesth., 43, 932. Tobias, M. A, Nassar, W. Y., and Richards, D. C. (1977): "Naso-tracheal jet ventilation for microlaryngeal procedures", Anaesthesia, 32, 359. Vourch, G., Freche, G., and Tran Ban Hui, I. H. P. (1977): "Suspension laryngoscopy under general anaesthesia. A technique using an injector", Anaesthesia, 32, 803.
