- Email: [email protected]
A rockwool fibre worker with lung fibrosis
CORRESPONDENCE
Sir—In his commentary on awareness in anaesthesia, Bruno Simini1 rightly emphasises that postoperative memory of intraoperative events is only the most extreme (and presumably least frequent) part of the phenomenon. On the other hand it is not possible to get any impression of unconscious perception. The patients with awareness described in the study by Rolf Sardin and colleagues2 seem to have had only temporary recall, but it is only a matter of belief (or hope) to imagine that all perception was then simultaneously switched off. Anaesthesia is, as Simini initially states, an “indeterminable state”. There can be no doubt that what is commonly understood as awareness in anaesthesia is undesirable and potentially harmful. It is quite possible that such awareness during anaesthesia occurs all the time, or at least very often, without necessarily causing harm to the patients. How can you prevent something which occurs very often, do you need to prevent it, and are other measures necessary? The differences between sleep and anaesthesia is an ill-explored area.3 Patients and surgeons expect sleep during anaesthesia and it is generally possible to provide this impression (no recall of intraoperative events). However, anaesthetists should not believe that no intraoperative awareness will occur. Patients should be treated with respect during anaesthesia in case of awareness: no personal remarks should be made and there should be no discussion of metastasis or bad prognosis.4 Such restriction to comment would be difficult for surgeons who expect total unconsciousness in their patients. Even if benzodiazepines fail to prevent recall of intraoperative events, they may, in the condition of unconscious awareness, be useful as anxiolytics (which is, of course, entirely speculative). Use of devices such as electroencephalography could mislead the anaesthetist to use more anaesthetic than would be good for the patient, in terms of recovery from an operation. The method used by Sandin and colleagues for finding 19 cases of awareness among 11 785 patients was laborious but valuable. Following surgery patients should be asked about conscious awareness (or bad dreams) upon discharge from recovery, and anaesthetists should be alerted to positive reports. Postoperative questioning 1 day or more after surgery should be considered part of
THE LANCET • Vol 355 • May 13, 2000
the anaesthetist’s job, because it will prompt precautions against this and other adverse consequences and allow patients to receive therapy when necessary. John Schou County Hospitals, D-79539 Lörrach, Germany (e-mail: [email protected]) 1
2
3 4
Simini B. Awareness of awareness during general anaesthesia. Lancet 2000; 355: 672–74. Sandin RH, Enlund G, Samuelsson P, Lennmarken C. Awareness during anaesthesia: a prospective case study. Lancet 2000; 355: 707–11. Schou J. A philsophical approach to anaesthesia. Copenhagen: Alix Publ, 1994. Bennett HL. Influencing the brain with information during general anaesthesia: a theory of unconscious hearing. In: Bonke B, Fitch W, Millar K, eds. Memory and awareness in anaesthesia. Amsterdam: Swets & Zeitlinger, 1990: 50–56.
A rockwool fibre worker with lung fibrosis Sir—Richard Hubbard and colleagues (Feb 5, p 466)1 describe the increased mortality from cryoptogenic fibrosing alveolitis in metal-workers. We describe a case of rockwool-induced lung fibrosis, in a patient who had a history of rockwool inhalation for 12 years. A man aged 72 years was admitted to the Tohoku University Hospital, Sendai, Japan, in Sept, 1998, because of progressive pleural thickness in the lower and apical part of the right lung, and reticular shadows in the lower lobe of both sides of the lung seen on chest radiographs. In the preceding 12 years, the patient had been employed full time as a rockwool spray insulator.
Rockwool is a man-made mineral fibre. He smoked 10 cigarettes a day for 20 years. A chest radiograph done before he started this work showed no abnormal shadows. He had no cough, sputum, dyspnoea, or fever. A computed-tomography (CT) scan of his chest showed pleural thickness and calcification, linear, trabecular, and round nodular shadows on both sides of the lower lobes of both lungs. The heart was normal but he had crepitations of lung sounds in both sides of the lower lung field. PaO2 was 78 mm Hg, PaCO2 was 42 mm Hg, and pH was 7·44 (breathing room air). Spirometry showed a mild restrictive impairment with a forced vital capacity of 72% and a forced expiratory volume in 1 s of 92%. Peripheral blood and serum were normal for all values tested. Autoimmune antibodies including antibodies to nuclei and DNA were negative. Light-microscope examination of lung tissue from the round nodular shadow obtained by aspiration needle lung biopsy guided by the CT scan, showed interstitial pulmonary fibrosis with hypertrophy of the alveolar wall and foreign-body deposition. No asbestos body, inflammatory granuloma, lung cancer, or malignant methothelioma was found. Electron-microscope examination of the same lung specimen showed nonstructural fibres (<2·5 m long and 0·3 m in diameter), which had identical dimensions to rockwool fibre (figure). Man-made mineral fibres, including rockwool, have been widely used because of their thermal, acoustic, and fire-resistance properties and to reduce asbestos use. Man-made mineral fibres have been said not to induce the lung fibrosis seen in
Electron microscopy shows deposition of nonstructural fibres in the macrophages (black arrows)
1723
CORRESPONDENCE
asbestosis and silicosis.2 Risk factors of the biological effects of inhaled fibres of asbestos and silica on lung cells are duration of exposure, cumulative exposure, characteristics and size of fibres, and exposure to other pollutants, such as cigarette smoking.3,4 The size of fibres has been thought to be associated with the biological effects, because small fibres are easily inhaled and deposited in the lung, but large fibres are easily cleared from the lung.2,4 Workers involved in the production of smaller diameter (1 m) glasswool fibres show an increased risk of small opacities on chest radiographs.5 We recommend that people who work with rockwool should be followed up with chest radiographs. Mutsuo Yamaya, Katsutoshi Nakayama, Masayoshi Hosoda, Masaru Yanai, *Hidetada Sasaki Department of Geriatric and Respiratory Medicine, Tohoku University School of Medicine, Sendai 980-8574, Japan 1
2
3
4
5
Hubbard R, Cooper M, Antoniak M, et al. Risk of cryptogenic fibrosing alveolitis in metal workers. Lancet 2000; 355: 466–67. Weil H, Jones RN. Occupational pulmonary diseases. In: Fishman AP, ed. Pulmonary diseases and disorders. New York: McGraw-Hill, 1988: 819–60. Merchant JA. Human epidemiology: a review of fiber type and characteristics in the development of malignant and nonmalignant disease. Environ Health Perspect 1990; 88: 287–93. Mossman BT, Chung A. Mechanisms in the pathogenesis of asbestosis and silicosis. Am J Respir Crit Care Med 1998; 157: 1666–80. Weil H, Hughes JM, Hammad YY, Glindmeyer HW III, Sharon G, Jones RN. Respiratory health in workers exposed to man-made vitreous fibers. Am Rev Respir Dis 1983; 128: 104–12.
Treatment of pediculosis capitis by dry combing Sir—Olivier Chosidow (March 4, p 819)1 highlights the lack of good evidence to support non-drug treatments for the treatment of head lice. The incidence of head louse infestation is increasing,2 with some schools reporting outbreaks more than twice a year. Pediculicides in use in the UK include organophosphates (malathion), pyrethroids (permethrin and phenothrin), and carbaryl. None of these drugs is considered safe for people with asthma, in children younger than 6 months, or in contact with broken skin. Permethrin should not be used in pregnancy and lactation and carbaryl may be carcinogenic.3 There is widespread resistance to
1724
permethrin and malathion in the UK.2 Physical removal of lice and nits using a nit comb requires that the hair is wet and is combed with a special fine toothed nit comb and conditioner for at least 30 min every third or fourth day. There is no reliable evidence for the effectiveness of this method.1,2 With the hair wet and full of conditioner, it is difficult to see whether any lice or nits have been removed. However, dry combing, which is easier to do, allows success of louse removal to be seen and has been successful in ten out of ten separate infestations. With the infested person’s head over a sink the hair is brushed to remove knots and then combed with a nit comb from the crown down towards the sink. All lice removed can be inspected, counted, then washed away. The appearance of nits of different size and colour (younger ones are pale) suggests several generations (ie, longer duration of the infestation). The combing process is continued for at least 1 minute after the last nit has been seen. The back of the head is treated in a similar way. If the child does not lean backwards over the sink, nits can be caught on a white piece of paper. This procedure is repeated at least three times on the first day then twice a day for 5 days after the last louse has been seen. Thereafter, combing can be reduced to once a day, unless further lice have been seen. Since nits hatch within 6–10 days, and take a further 10 days to mature, the child can be judged clear of lice and viable nits 3 weeks after the last louse has been found. Although this method of combing does not remove nits, in all of the 10 incidents of infestation cases were free of lice within a week, and there was no late recurrence suggestive of hatched nits. This method has the advantage that it can be used repeatedly without fear of toxicity, there are no contraindications in asthmatic children or with pregnancy, and resistance does not develop. It is preferable to the method of wet combing, because the success of louse removal can be closely monitored and it can be repeated without the need to wash and dry the hair, as often as the child will allow. C Roffe Department of Geriatric Medicine, City General Hospital, Keele University, Stoke-on-Trent ST4 6QG, UK 1 2 3
Chosidow O. Scabies and pediculosis. Lancet 2000; 355: 819–26. Anon. Treating head lice. Effective Mat 1999; 4: 1–3. Joint Formulary Committee. Skin. In: British National Formulary 38. The Bath Press, Bath. Sept 1999: 522–25.
Needless treatment for presumed malignancy Sir—Sigi Rotmensch and Laurence Cole’s report (Feb 26, p 712)1 highlights the importance of a constructive relationship between pathology laboratory workers and clinicians, which requires informed discussion of results. The investigators recommend that human chorionic gonadotropin (hCG) should be measured in urine to confirm the presence of hCG in serum and avoid unnecessary treatment of women who have false positive serum hCG results. We agree with this suggestion, but fear that it will prove difficult to put into practice. Most laboratories which offer a clinical service for hCG measurements use commercial assays, most of which are not validated for measurement in urine. Laboratories which wish to use commercial assays for urine need to validate the use of the assay for urine. The poor performance in external quality assurance schemes of assays for cortisol in urine illustrates the inaccuracies introduced when methods applicable to serum or plasma are applied to urine without proper validation. It would be difficult to implement Rotmensch and Cole’s recommendation without the support of a network of laboratories that have validated urine hCG methods. Our own data highlight the unsuitability of urine as a matrix. Using our own validated urine hCG assay2 we selected 54 urine samples with results of less than 2 IU/L. When assayed using the ACS180 method (Bayer Diagnostics, Newbury, UK), the mean was 6·0 IU/L (95% CI 2·7–9·2 IU/L). In a separate study, we have attempted to adapt the Roche 2010 assay (Lewes, Brighton, UK) for urine analysis. Dilution of five urine samples with hCG concentrations of 11 500–47 000 IU/L in urine with undetectable hCG gave a mean recovery of only 54·2% (95% CI 43·2–65·2). Neither Bayer nor Roche claim that their assays should be used with urine. Our experience emphasises the need for careful validation of any serum assay that the laboratory chooses to use. We have developed an alternative strategy. hCG concentrations in serum are rarely static: they usually increase or decrease consistently. Time is often a good discriminator of the false positive hCG result. If a serum hCG concentrations does not rise or fall there could be an artefact to blame. As Rotmensch and Cole showed, heterophilic antibodies are a common cause of a false positive hCG result. A simple means of testing for the
THE LANCET • Vol 355 • May 13, 2000
Sir—In his commentary on awareness in anaesthesia, Bruno Simini1 rightly emphasises that postoperative memory of intraoperative events is only the most extreme (and presumably least frequent) part of the phenomenon. On the other hand it is not possible to get any impression of unconscious perception. The patients with awareness described in the study by Rolf Sardin and colleagues2 seem to have had only temporary recall, but it is only a matter of belief (or hope) to imagine that all perception was then simultaneously switched off. Anaesthesia is, as Simini initially states, an “indeterminable state”. There can be no doubt that what is commonly understood as awareness in anaesthesia is undesirable and potentially harmful. It is quite possible that such awareness during anaesthesia occurs all the time, or at least very often, without necessarily causing harm to the patients. How can you prevent something which occurs very often, do you need to prevent it, and are other measures necessary? The differences between sleep and anaesthesia is an ill-explored area.3 Patients and surgeons expect sleep during anaesthesia and it is generally possible to provide this impression (no recall of intraoperative events). However, anaesthetists should not believe that no intraoperative awareness will occur. Patients should be treated with respect during anaesthesia in case of awareness: no personal remarks should be made and there should be no discussion of metastasis or bad prognosis.4 Such restriction to comment would be difficult for surgeons who expect total unconsciousness in their patients. Even if benzodiazepines fail to prevent recall of intraoperative events, they may, in the condition of unconscious awareness, be useful as anxiolytics (which is, of course, entirely speculative). Use of devices such as electroencephalography could mislead the anaesthetist to use more anaesthetic than would be good for the patient, in terms of recovery from an operation. The method used by Sandin and colleagues for finding 19 cases of awareness among 11 785 patients was laborious but valuable. Following surgery patients should be asked about conscious awareness (or bad dreams) upon discharge from recovery, and anaesthetists should be alerted to positive reports. Postoperative questioning 1 day or more after surgery should be considered part of
THE LANCET • Vol 355 • May 13, 2000
the anaesthetist’s job, because it will prompt precautions against this and other adverse consequences and allow patients to receive therapy when necessary. John Schou County Hospitals, D-79539 Lörrach, Germany (e-mail: [email protected]) 1
2
3 4
Simini B. Awareness of awareness during general anaesthesia. Lancet 2000; 355: 672–74. Sandin RH, Enlund G, Samuelsson P, Lennmarken C. Awareness during anaesthesia: a prospective case study. Lancet 2000; 355: 707–11. Schou J. A philsophical approach to anaesthesia. Copenhagen: Alix Publ, 1994. Bennett HL. Influencing the brain with information during general anaesthesia: a theory of unconscious hearing. In: Bonke B, Fitch W, Millar K, eds. Memory and awareness in anaesthesia. Amsterdam: Swets & Zeitlinger, 1990: 50–56.
A rockwool fibre worker with lung fibrosis Sir—Richard Hubbard and colleagues (Feb 5, p 466)1 describe the increased mortality from cryoptogenic fibrosing alveolitis in metal-workers. We describe a case of rockwool-induced lung fibrosis, in a patient who had a history of rockwool inhalation for 12 years. A man aged 72 years was admitted to the Tohoku University Hospital, Sendai, Japan, in Sept, 1998, because of progressive pleural thickness in the lower and apical part of the right lung, and reticular shadows in the lower lobe of both sides of the lung seen on chest radiographs. In the preceding 12 years, the patient had been employed full time as a rockwool spray insulator.
Rockwool is a man-made mineral fibre. He smoked 10 cigarettes a day for 20 years. A chest radiograph done before he started this work showed no abnormal shadows. He had no cough, sputum, dyspnoea, or fever. A computed-tomography (CT) scan of his chest showed pleural thickness and calcification, linear, trabecular, and round nodular shadows on both sides of the lower lobes of both lungs. The heart was normal but he had crepitations of lung sounds in both sides of the lower lung field. PaO2 was 78 mm Hg, PaCO2 was 42 mm Hg, and pH was 7·44 (breathing room air). Spirometry showed a mild restrictive impairment with a forced vital capacity of 72% and a forced expiratory volume in 1 s of 92%. Peripheral blood and serum were normal for all values tested. Autoimmune antibodies including antibodies to nuclei and DNA were negative. Light-microscope examination of lung tissue from the round nodular shadow obtained by aspiration needle lung biopsy guided by the CT scan, showed interstitial pulmonary fibrosis with hypertrophy of the alveolar wall and foreign-body deposition. No asbestos body, inflammatory granuloma, lung cancer, or malignant methothelioma was found. Electron-microscope examination of the same lung specimen showed nonstructural fibres (<2·5 m long and 0·3 m in diameter), which had identical dimensions to rockwool fibre (figure). Man-made mineral fibres, including rockwool, have been widely used because of their thermal, acoustic, and fire-resistance properties and to reduce asbestos use. Man-made mineral fibres have been said not to induce the lung fibrosis seen in
Electron microscopy shows deposition of nonstructural fibres in the macrophages (black arrows)
1723
CORRESPONDENCE
asbestosis and silicosis.2 Risk factors of the biological effects of inhaled fibres of asbestos and silica on lung cells are duration of exposure, cumulative exposure, characteristics and size of fibres, and exposure to other pollutants, such as cigarette smoking.3,4 The size of fibres has been thought to be associated with the biological effects, because small fibres are easily inhaled and deposited in the lung, but large fibres are easily cleared from the lung.2,4 Workers involved in the production of smaller diameter (1 m) glasswool fibres show an increased risk of small opacities on chest radiographs.5 We recommend that people who work with rockwool should be followed up with chest radiographs. Mutsuo Yamaya, Katsutoshi Nakayama, Masayoshi Hosoda, Masaru Yanai, *Hidetada Sasaki Department of Geriatric and Respiratory Medicine, Tohoku University School of Medicine, Sendai 980-8574, Japan 1
2
3
4
5
Hubbard R, Cooper M, Antoniak M, et al. Risk of cryptogenic fibrosing alveolitis in metal workers. Lancet 2000; 355: 466–67. Weil H, Jones RN. Occupational pulmonary diseases. In: Fishman AP, ed. Pulmonary diseases and disorders. New York: McGraw-Hill, 1988: 819–60. Merchant JA. Human epidemiology: a review of fiber type and characteristics in the development of malignant and nonmalignant disease. Environ Health Perspect 1990; 88: 287–93. Mossman BT, Chung A. Mechanisms in the pathogenesis of asbestosis and silicosis. Am J Respir Crit Care Med 1998; 157: 1666–80. Weil H, Hughes JM, Hammad YY, Glindmeyer HW III, Sharon G, Jones RN. Respiratory health in workers exposed to man-made vitreous fibers. Am Rev Respir Dis 1983; 128: 104–12.
Treatment of pediculosis capitis by dry combing Sir—Olivier Chosidow (March 4, p 819)1 highlights the lack of good evidence to support non-drug treatments for the treatment of head lice. The incidence of head louse infestation is increasing,2 with some schools reporting outbreaks more than twice a year. Pediculicides in use in the UK include organophosphates (malathion), pyrethroids (permethrin and phenothrin), and carbaryl. None of these drugs is considered safe for people with asthma, in children younger than 6 months, or in contact with broken skin. Permethrin should not be used in pregnancy and lactation and carbaryl may be carcinogenic.3 There is widespread resistance to
1724
permethrin and malathion in the UK.2 Physical removal of lice and nits using a nit comb requires that the hair is wet and is combed with a special fine toothed nit comb and conditioner for at least 30 min every third or fourth day. There is no reliable evidence for the effectiveness of this method.1,2 With the hair wet and full of conditioner, it is difficult to see whether any lice or nits have been removed. However, dry combing, which is easier to do, allows success of louse removal to be seen and has been successful in ten out of ten separate infestations. With the infested person’s head over a sink the hair is brushed to remove knots and then combed with a nit comb from the crown down towards the sink. All lice removed can be inspected, counted, then washed away. The appearance of nits of different size and colour (younger ones are pale) suggests several generations (ie, longer duration of the infestation). The combing process is continued for at least 1 minute after the last nit has been seen. The back of the head is treated in a similar way. If the child does not lean backwards over the sink, nits can be caught on a white piece of paper. This procedure is repeated at least three times on the first day then twice a day for 5 days after the last louse has been seen. Thereafter, combing can be reduced to once a day, unless further lice have been seen. Since nits hatch within 6–10 days, and take a further 10 days to mature, the child can be judged clear of lice and viable nits 3 weeks after the last louse has been found. Although this method of combing does not remove nits, in all of the 10 incidents of infestation cases were free of lice within a week, and there was no late recurrence suggestive of hatched nits. This method has the advantage that it can be used repeatedly without fear of toxicity, there are no contraindications in asthmatic children or with pregnancy, and resistance does not develop. It is preferable to the method of wet combing, because the success of louse removal can be closely monitored and it can be repeated without the need to wash and dry the hair, as often as the child will allow. C Roffe Department of Geriatric Medicine, City General Hospital, Keele University, Stoke-on-Trent ST4 6QG, UK 1 2 3
Chosidow O. Scabies and pediculosis. Lancet 2000; 355: 819–26. Anon. Treating head lice. Effective Mat 1999; 4: 1–3. Joint Formulary Committee. Skin. In: British National Formulary 38. The Bath Press, Bath. Sept 1999: 522–25.
Needless treatment for presumed malignancy Sir—Sigi Rotmensch and Laurence Cole’s report (Feb 26, p 712)1 highlights the importance of a constructive relationship between pathology laboratory workers and clinicians, which requires informed discussion of results. The investigators recommend that human chorionic gonadotropin (hCG) should be measured in urine to confirm the presence of hCG in serum and avoid unnecessary treatment of women who have false positive serum hCG results. We agree with this suggestion, but fear that it will prove difficult to put into practice. Most laboratories which offer a clinical service for hCG measurements use commercial assays, most of which are not validated for measurement in urine. Laboratories which wish to use commercial assays for urine need to validate the use of the assay for urine. The poor performance in external quality assurance schemes of assays for cortisol in urine illustrates the inaccuracies introduced when methods applicable to serum or plasma are applied to urine without proper validation. It would be difficult to implement Rotmensch and Cole’s recommendation without the support of a network of laboratories that have validated urine hCG methods. Our own data highlight the unsuitability of urine as a matrix. Using our own validated urine hCG assay2 we selected 54 urine samples with results of less than 2 IU/L. When assayed using the ACS180 method (Bayer Diagnostics, Newbury, UK), the mean was 6·0 IU/L (95% CI 2·7–9·2 IU/L). In a separate study, we have attempted to adapt the Roche 2010 assay (Lewes, Brighton, UK) for urine analysis. Dilution of five urine samples with hCG concentrations of 11 500–47 000 IU/L in urine with undetectable hCG gave a mean recovery of only 54·2% (95% CI 43·2–65·2). Neither Bayer nor Roche claim that their assays should be used with urine. Our experience emphasises the need for careful validation of any serum assay that the laboratory chooses to use. We have developed an alternative strategy. hCG concentrations in serum are rarely static: they usually increase or decrease consistently. Time is often a good discriminator of the false positive hCG result. If a serum hCG concentrations does not rise or fall there could be an artefact to blame. As Rotmensch and Cole showed, heterophilic antibodies are a common cause of a false positive hCG result. A simple means of testing for the
THE LANCET • Vol 355 • May 13, 2000