HALOTHANE HEPATOTOXICITY

1438 You raise the possibility that neutrons may be useful in other than squamous carcinoma. This has already been demonstrated. A controlled trial in the USA showed a significant advantage to the neutron-containing treatment of locally advanced prostatic cancer, both in local control and in survival.7 Cohen, et al8 reviewing the world results, reported 70% local control by neutrons in unresectable, non-epidermoid cancers in 600 patients. These included salivary gland tumours, soft tissue sarcoma, and melanoma. He drew attention to the consistency of the results from ten different centres. Your statement that the high-energy cyclotron at Clatterbridge Hospital on Merseyside will provide clear answers in the next few years is, unfortunately, incorrect. With the existing protocols it will take a decade to achieve results of any significance. In the meantime, patients with otherwise incurable tumours who could expect 70% chance of local control with neutrons have no access to neutron therapy in the UK. tumours

Fast Neutron Clinic, MRC Cyclotron Unit, Hammersmith Hospital, London W12 0HS 1. Griffin

MARY CATTERALL

TW, Pajak T, Laramore G, Davis L. Analysis of neutron radiotherapy complications. Bull Cancer (in press).

treatment

2. Medical Research Council Neutron Therapy Working Group. A comparative review of the Hammersmith (1970-75) and Edinburgh (1977-82) neutron therapy trials of certain cancers of the oral cavity, oropharynx, larynx and hypopharynx. Br J Radiol 1986; 59: 429-40. 3. Catterall M, Sutherland I, Bewley DK. First results of a randomized clinical trial of fast neutrons compared with X or gamma rays in treatment of advanced tumours of the head and neck. Br Med J 1975; ii: 653-56. 4. Catterall M, Bewley DK, Sutherland I. Second report on results of randomized clinical trial of fast neutrons compared with X or gamma rays in treatment of advanced tumours of head and neck. Br Med J 1977; i: 1642. 5. Griffin TW, Davis R, Laramore GE et al. Mixed beam radiation therapy for unresectable squamous cell carcinomas of the head and neck: The results of a randomized RTOG study. Int J Radiat Oncol Biol Phys 1984; 10: 2211-16. 6. Griffin TW, Davis R, Hendrickson FR, Maor MH, Laramore GE. Fast neutron radiation therapy for unresectable squamous cell carcinoma of the head and neck: The results of a randomized RTOG study. Int J Radiat Oncol Biol Phys 1984; 10: 2217-22. 7. Laramore GE, Krall JM, Thomas TJ, Griffin TW, Maor MH, Hendrickson F. Fast neutron radiotherapy for locally advanced prostate cancer: Results of an RTOG randomized study. Int J Radiat Oncol Biol Phys 1985; 2: 1621-27. 8. Cohen L, Hendrickson F, Kurup PD, et al. Clinical evaluation of neutron beam therapy: Current results and prospects 1983. Cancer 1985; 55: 10-17.

Penicillium spp identified in air from compressed air plant and from ICU.

plate) was found in both. Fungi (especially 47/M spp) are likely contaminants since they may be found in atmospheric air. Such a finding might be of major importance for immunosuppressed patients. Rhame et al2 noted the importance of atmospheric air as a vehicle for transport of Aspergillus spores, and have noted the value of an air-filtered air supply for reduction of infection in bonemarrow transplants. A research programme has been set up by the Department of Health and Social Security’s Health Building Directorate to investigate the potential microbiological problems of medical compressed air using a trial compressor which is being subjected to microbial challenges, and to which various types of HEPA filter are being added. Pending the outcome of this work any compressed air used for ventilating or humidifying patients should be filtered at the point of use. Department of Bacteriology, Addenbrooke’s Hospital, Cambridge CB2 2QQ

R. E. WARREN S. W. B. NEWSOM J. A. MATTHEWS

DHSS Health London NW1

L. W. M. ARROWSMITH

1.

Building Directorate,

Berg B, Bjerring P. Pneumatic surgical instruments and postoperative infection 1985;

ii:

1436. Streifel

2. Rhame FS, in the patient

at

Lancet

AJ, Kersey JH, McGlave PB. Extrinsic risk factors for pneumonia high risk of infection. Am J Med 1984; 76: 42-52.

MEDICAL GRADE COMPRESSED AIR

SIR,-Equipment for producing compressed air does not include special antibacterial filters, and in the UK at least no such requirement has been identified. UK plants should, however, comply with Hospital Technical Memorandum no 22. Hospitals have central air-compressor systems supplying pipelines. The area that concerns us most is the intensive care unit (ICU) where some ventilators are air-driven and where some equipment delivers compressed air to the patient’s lungs. Like Berg and Bjerringl we have

on

occasion demonstrated microbial contamination in the air,

although it is very difficult to separate this from contamination in room air, unless the compressed air is collected directly and separately into an air sampler. The medical air compressor uses outdoor air, and the main steps in "conditioning" are oil removal and desiccation, and then coarse filtration to prevent particles of desiccant entering the pipework. The dewpoint of the end product is so low that Pseudomonas spp would find it hard to survive. However, we did find gram-negative bacilli in both ICU air and in the discharge of the compressed air receiver (upstream of the conditioning equipment) on one occasion. A drain had blocked, possibly due to excess oil, leaving water in the compressed air receiver. It is difficult to envisage how skin bacteria

reported1

could be found in the air, and we wonder if those were artefacts of the collecting method. By a careful technique, in which 1800 litres of air was taken from the compressed air plant test point in a hospital basement into a sterile impinger containing collection fluid, and a similar volume of ICU air was sampled into another impinger, Penicillium spp (see

HALOTHANE HEPATOTOXICITY

SIR,-Your May 31 editorial (p 1251) provides important insight into knowledge of halothane hepatitis and raises some interesting discussion points. Perhaps now, in view of the fact that there are now many alternatives, repetitive halothane anaesthesia should not be given in any circumstances. The risk of hepatitis should also preclude the use of this agent in seriously ill or hypoxic patients. Giving patients bracelets to wear should be encouraged only if the "at risk" group has been identified by a specialist liver unit, otherwise a huge population of "false positives" who have had malaise or fever postoperatively but who are not at risk of halothane hepatitis will be generated. The suitability of enflurane as an alternative to halothane for repetitive anaesthesia is controversial. There may be cross-sensitivity to halothane, and enflurane also undergoes some hepatic metabolism. There has been a report! of 24 cases of enflurane-associated hepatitis. The ideal agent for situations requiring repetitive inhalational anaesthesia now appears to be isoflurane. Department of Anaesthesia, Royal Marsden Hospital, London SW3 6JJ

1. Lewis

P. N. ROBINSON B. M. BRAY

JH, Zimmerman HJ, Ishak KG, Mullick FG. Enflurane hepatotoxicity: a Ann Intern Med 1983; 98: 984-92.

clinicopathologic study of 24 cases.