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Comment

the positioning as normal. The small size of these tubes has caused no problems with ventilation as a result of surgical manipulation or in obese patients. The head-up position normally used for thyroid surgery is obviously helpful in the latter context. P CHARTERS BA MD MRCP FFARCS Consultant Anaesthetist D CAVE-BIGLEY MD FRCS Consultant Surgeon Walton Hospital Liverpool

References I Tanigawa K, Inoue Y, Iwata S. Protection of recurrent laryngeal nerve during neck surgery: A new combination of neurotracer, laryngeal mask airway, and fibreoptic bronchoscope. Anesthesiology 1991;74:966-7. 2 Charters P, Cave-Bigley D. Should a laryngeal mask be routinely used in patients undergoing thyroid surgery? Anesthesiology 1991;75:918-19. We read the paper written by R A Greatorex and N M Denny (Annals, November 1991, vol 73, p352) with interest, but feel several points require further comment. The use of the fibreoptic laryngoscope to visualise the vocal cords while simultaneously stimulating the recurrent laryngeal nerve (RLN) during thyroid surgery has been described previously (1,2). These patients had endotracheal intubation which did not interfere with assessing vocal cord movement. Though we agree with the authors that vocal cord trauma is prevented using the Laryngeal Mask Airway (LMA) this risk has been estimated at only 3% using endotracheal tubes (3). More importantly, identification of the external laryngeal nerve (ELN) in addition to the RLN reduces the incidence of voice change from 25% to 5% (3). Damage to the ELN causes paralysis of the cricothyroid muscle resulting in hoarseness and a reduction in both vocal pitch and range (4). We are unclear as to their advice on the use of LMA during thyroid surgery when the trachea is deviated or narrowed. In their conclusion they assert surgery can be safely undertaken with the LMA in these patients, but contradict this in their next sentence by stating tracheal narrowing or deviation is a relative

contraindication to the use of LMA. We should mention two patients with retrosternal goitres causing tracheal compression and who presented with stridor on whom we have operated (see Fig. 1). Anaesthesia was maintained only by the use of a reinforced endotracheal tube and clearly would not have been possible using the LMA. D J PREMACHANDRA FRCS Consultant ENT Surgeon James Paget Hospital Great Yarmouth R D R MCRAE FRCS Registrar in ENT Surgery The Royal London Hospital Whitechapel, London References I Premachandra DJ, Radcliffe GJ, Stearns MP. A technique for intraoperative identification of the recurrent laryngeal nerve and demonstration of its function. Laryngoscope 1990;100:94-6. 2 Premachandra DJ, Milton CM. Cord examination after thyroidectomy. Anaesthesia 1989;44:937. 3 Kark AE, Kissin MW, Auerbach R, Meikle M. Voice changes after thyroidectomy: role of external laryngeal nerve. Br Med J 1984;289:1412-15. 4 Friedman M, Toriumi DM. Functional identification of the external laryngeal nerve during thyroidectomy. Laryngoscope 1986;95: 1291-2.

Branchial cysts: congenital or acquired? As we had a similar case recently I read with interest the article by C Shinkwin et al. (Annals, November 1991, vol 73, p379). It is important to stress the role of fine-needle aspiration cytology [FNAC] in neck lumps, even if one is clinically confident of the diagnosis. Our patient had what was thought to be the most classical thyroglossal cyst. She was discussed with all the students! Histological report showed how wrong we were and she underwent a second procedure to remove the primary papillary tumour in the thyroid. An 'FNA in time might save the knife the second time'. R SRINIVASAN Locum Senior Surgical Registrar Leicester Royal Infirmary

Prevention of occupational transmission of HIV in the ENT clinic

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We found the article by Rowe-Jones and Pringle (Annals, January 1992, vol 74, pS) on the prevention of HIV transmission in the ENT clinic most interesting and write to make one comment on the common use of Rogers' Crystal Spray(* as a possible source of cross-infection. Careful consideration has been given to cross-infection, in particular to the prevention of hepatitis B and HIV transmission. For ENT staff the management of epistaxis carries potential hazards, but there is also a risk of patient-to-patient cross-infection with the administration of local anaesthetic. Topical local analgesia is commonly administered via a Rogers' Crystal Spray and not infrequently blood from the nasal cavity syphons back into the lignocaine and adrenaline solution. It is essential, therefore, that the equipment be sterilised after each use and replenished with fresh local anaesthetic solution. The unrecognised syphoning of nasal fluid in other situations

G =Large retrosternal goitre. T =Compressed trachea. Figure 1 Enhanced CAT scan showing the compressed retro-

* Rogers' Crystal Spray® manufactured by Frank A Rogers, 1 Beaumont Street, London, and is available from local hospital

sternal trachea.

suppliers.

Comment could theoretically allow cross-infection, and although the conscientious clinician cleans the glass tip between patients this would not prevent cross-contamination. Perhaps the 'time honoured' use of Rogers' Crystal Spray should be reviewed. SIMON N ROGERS MB ChB FDSRCS Senior House Officer NICHOLAS VIOLARIs FRCS Senior Registrar Dudley Road Hospital Birmingham The paper by Rowe-Jones and Pringle (Annals, January 1992, vol 74, p5) raises some interesting points about how surgeons are facing up to the hazard of HIV infection. Of the 179 HIV-positive patients seen in the ENT clinic at St Mary's between 1989 and 1991, 20 (13%) of cases had pathology that was only visible by mirror examination or flexible endoscopy, and therefore it is essential not to shirk from giving all HIV-positive patients a full examination in the ENT clinic. Nevertheless, there have only been two occasions when salivary contamination of the examiner's facial region, fortunately protected by goggles, has occurred. Epistaxis, especially associated with zidovudine-related marrow-suppression, complicated 3% of our recent workload and so presents a real risk. Therefore, I was very encouraged to see the attention respondents gave to this situation. The questionnaire correctly distinguished between 'highrisk' and other patients. The majority of the patients we see fall into one of the well-recognised risk categories, but among the patients I have seen are a 16-year-old girl and a septagenarian lady, both with heterosexually acquired infection. Whilst such cases are rare, this may not always be the case as patterns of spread change, and so restriction of prophylactic measures to those judged 'at-risk' may become increasingly ineffective. With this in mind, I should like to draw attention to some of the practical measures outlined by Stotter et al. (1). We endorse the message carried in the Assessor's comment, and suggest a reappraisal of our practices for all patients and not just for those with overt AIDS. MARTIN A BIRCHALL FRCS FRCS(Otol) ENT Registrar St Mary's Hospital London

Reference I Stotter AT, Vipond MN, Guillou PJ. The response of general surgeons to HIV in England and Wales. Ann R Coll Surg Engl 1990;72:281-6.

Paraoesophageal hiatus hernia: surgery for all ages The paper by Hallissey et al. (Annals, January 1992, vol 74, p23) implies that mobilisation of the omentum and transverse colon to the left upper quadrant was advocated by Tanner in the surgical correction of paraoesophageal hernia. This is incorrect. Tanner devised this procedure for the treatment of gastric volvulus associated with eventration of the left diaphragm. He described only two patients with paraoesophageal hernia in that paper and both were treated by hiatal repair only. R WHISTON FRCS Registrar J D STAMATAKIS MS FRCS Consultant The Princess of Wales Hospital Bridgend

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Contamination of underwater seal drainage systems in thoracic surgery The article by Hornick et al. (Annals, January 1992, vol 74, p26) introduces a subject which we feel has previously been neglected. While we would agree with the authors' main conclusion that underwater seal drainage systems may be left for up to 6 days postoperatively without routine replacement, other aspects of the paper merit discussion. Only to culture the underwater seal fluid ignores the possibility of contamination of the intrathoracic part of the drain occurring via the open drain wound with a foreign body (the drain) passing through it. We suggest that if the authors had submitted the tips of the drains for culture, when removed, their results may have been different. The number of patients (38) in this study is too small to make any comment on the incidence of wound infections given the reported rate of 1% in non-cardiac thoracic surgery (1). The antibiotic regimen described (flucloxacillin 500 mg and ampicillin 500 mg four times daily until drains removed) would, we feel, result in a delayed presentation of any wound infection. By only reporting wound infections if present on the day of drain removal (in all patients by 6 days postoperatively and, in most, earlier) those occurring later will be missed. We suggest that this regimen is not typical in non-cardiac thoracic surgery and is unnecessarily prolonged. In a randomised controlled trial involving 119 patients and 185 drainage systems, we found that significant contamination did occur, even in those present for less than 6 days. However, these did not appear to be associated with clinical sequelae. There was no significant difference between systems changed daily and those left unchanged until removal. ALASTAIR N J GRAHAM FRCSEd Surgical Registrar JOHN R P GIBBONS MBE TD FRCS FCCP Consultant Thoracic Surgeon JIM A MCGUIGAN FRCSEd Consultant Thoracic Surgeon Royal Victoria Hospital Belfast Reference I Wells FC, Newsom SWB, Rowlands C. Wound infection in cardiothoracic surgery. Lancet 1983;1:1209-10.

Endoscopic transanal resection of large vilious tumours of the rectum We read with interest the paper by Stephenson et al.(Annals, January 1992, vol 94, p54) describing the endoscopic resection of six large villous tumours of the rectum varying in size up to 5 cm and arising up to 12 cm from the anal verge. When considering the alternatives to endoscopic resection, the authors state that submucous resection of a villous adenoma is generally only applicable to small, mobile, easily accessible lesions, and they offer endoscopic resection as an alternative to a more radical resection. In a series of 98 rectal villous adenomas in 87 patients reported from this unit (1), 61 sessile lesions could not be snared and 51 (84%) of these lesions were successfully removed by the technique of submucous resection employed in our unit (2) with low morbidity and no mortality. Far from being small, accessible and mobile, these lesions were up to 12 cm in length, extending up to 18 cm from the anal verge. Many were circumferential and fixed by areas of previous biopsy or malignant transformation with invasion, the latter having occurred in 14 patients. Our overall benign recurrence rate of 12.5% probably reflects to some extent a field change, since the interval from surgery to recurrence was up to