1481
Activists, depending on their stance, will threaten
to use
against manufacturers who give offence by or by withholding an abortifacient product. supplying Abortion opponents have threatened a boycott of all products of manufacturers of antiprogestagens, and of products of their parent companies. Abortion rights supporters similarly pressured the Governor of Idaho with a boycott of that state’s agricultural products, particularly potatoes, and deterred him from signing anti-abortion market forces
legislation. Manufacturers should not succumb to the pressure from either direction. They should respect the plurality of views and make products available for use according to the judgment and conscience of patients and the health professionals. Their goal must continue to be the supply of scientifically proven products to doctors willing to supply services that their patients choose. A company that decides not to seek approval of a potentially safe and effective product that serves a legitimate need should respect market plurality by making the product available to other manufacturers--or surrender its rights. 1. Editorial. Mifepristone—contragestive agent or medical abortifacient? Lancet 1987; ii: 1308-10. 2. Gupta JK, Johnson N. Effect of mifepristone on the pregnant and non-pregnant cervix. Lancet 1990; 335: 1238-40. 3. Silvestre L, Dubois C, Renault M, Rezvani Y, Baulieu E-E, Ulmann A. Voluntary interruption of pregnancy with mifepristone (RU 486) and a prostaglandin analogue. A large-scale French experience. N Engl J Med 1990; 322: 645-48. 4. Rodger MW, Baird DT. Induction of therapeutic abortion in early pregnancy with mifepristone in combination with prostaglandin pessary. Lancet 1987; ii: 1415-18. 5. UK Multicentre Trial. The efficacy and tolerance of mifepristone and prostaglandin in first trimester termination of pregnancy. Br J Obstet Gynaecol 1990; 97: 480-86. 6. Anon. Mifepristone: application for UK licence. Lancet 1990; 336: 240. 7. McKenzie I. The potential effects on NHS resources. In: Williams C, ed. The abortion pill. London: Birth Control Trust, 1990: 41-47. 8. Cook RJ. Antiprogestin drugs: medical and legal issues. Fam Plann Perspect 1989; 21: 267-72.
the
haemoglobin available for measured carbon monoxide
uptake. A 1% increase in carbon monoxide saturation of haemoglobin will reduce the measured TLco by 1 %;9 since smokers may have up to 10% saturation of their haemoglobin, the relation of the test to smoking habit is important for interpretation of the results. TLco is reduced in anaemia and increased in polycythaemia. The constellation of dyspnoea, infiltrates on the chest radiograph, non-obstructive spirometric findings, and reduced lung volumes with a reduced TLco defines restrictive lung disease. These conditions include a group of interstitial disorders such as fibrosing alveolitis, sarcoidosis, asbestosis, farmer’s lung, connective tissue diseases, and polyarteritis nodosa. There is often associated hypoxaemia, because of alterations in ventilation and perfusion matching and not, as formerly thought, because of an alveolar block. In such disorders the TLco can be used as an indicator of progression and sometimes—eg, in sarcoidosis-as an indicator of the response to treatment, although this application is not universally accepted.lO Low values of TLco also occur in association with obstructive lung disease, especially when there is a nonuniform distribution of alveolar ventilation to perfusion, as in cystic fibrosis, and also in emphysema owing to a decrease in the gas exchange area. TLco can help to define subgroups of patients with airways obstruction. Knudson and colleagues lately described the relation between asthma and TLco in patients with obstructive airways disease.l TLC() was normal or increased in patients with asthma but reduced in patients with airways obstruction in whom asthma had not been diagnosed and who smoked. Pulmonary thromboembolic disorders also reduce TL, whereas pulmonary haemorrhage will increase the Kco because haemoglobin is sequestered in the alveolar compartment. Overall, TLco and Kco are subtle indicators of lung function; changes are not specific to individual disorders, although they can help in the diagnosis and management of parenchymal lung disease.
DIFFUSION CONFUSION Epidemiology standardisation project. Am Rev Respir Dis 1978; 118: 1-120. 2. Spicer WS, Johnson RL, Forster RE. Diffusing capacity and blood flow in different regions of the lung. J Appl Physiol 1962; 17: 587-95. 3. Filley GF, MacIntosh DJ, Wright GW. CO uptake and pulmonary diffusing capacity in normal subjects at rest and during exercise. J Clin Invest 1954; 33: 530-39. 4. Lewis BM, Lin T, Noe FE, Hayford-Welsing EJ. The measurement of pulmonary diffusing capacity for carbon monoxide by a rebreathing method. J Clin Invest 1959; 38: 2073-86. 5. Crapo RO, Morris AH, Gardener RM, Schaap RN. Computational techniques for rebreathing lung volume and pulmonary capillary blood flow. J Appl Physiol 1982; 52: 1375-77. 6. Knudson RJ, Kaltenborn WT, Knudson DE, Burrows B. The single-breath carbon monoxide diffusing capacity: reference equations derived from a healthy nonsmoking population and effects of hematocrit. Am Rev Respir Dis 1987; 135: 805-11. 7. Cadigan JB, Marks A, Ellicott MF, Jones RH, Gaensler EA. An analysis of factors affecting the measurement of pulmonary diffusing capacity by the single breath method. J Clin Invest 1961; 40: 1495-514. 8. Hyland RH, Krastins IRB, Aspin N, Mansell AL, Zanid N. Effect of body position on carbon monoxide diffusing capacity in asymptomatic smokers and nonsmokers. Am Rev Respir Dis 1978; 117: 1045-53. 9. Knudson RJ, Kaltenbom WT, Burrows B. The effects of cigarette smoking and smoking cessation on the carbon monoxide diffusing capacity of the lung in asymptomatic subjects. Am Rev Respir Dis 1989; 1. Ferns GB.
Oxygen diffuses from air in the alveolar space to haemoglobin in the red blood cell across a series of resistances-alveolar lining cells; lung interstitium; endothelial cells; a plasma layer; erythrocyte membrane; erythrocyte cytoplasm; and the haemoglobin molecule. Thus diffusion may be altered by changes in any of these Since diffusion of oxygen (D2) is difficult to for routine purposes carbon monoxide diffusion is measure, measured instead.l-4 However, there are differences between Dca and Doz because of the nature of the gases, concentration gradients, and binding characteristics of the gases to haemoglobin. Carbon monoxide diffusion is usually called transfer factor (TL,). The single-breath method, which is most commonly used, includes a measure of alveolar volume (VJ. The ratio TLco/VA or Kco indicates the quality of diffusion in ventilated alveoli. Technical factors (eg, breath-holding time and incorrect collection of alveolar gas) may affect TLco results. There are physiological variations in TLco according to gender and height; TLco also declines with age. Consequently, correction factors are usually applied and normal ranges and predicted values are used to aid interpretation.6 TL, increases with lung inflation,7 and in the supine posture owing to the effect of gravity on ventilation perfusion matching.8 Tobacco smoking reduces structures.
140: 645-51.
Ogilvie C. The single-breath carbon monoxide transfer test 25 years on: a reappraisal. 2-clinical considerations. Thorax 1983; 38: 5-9. 11. Knudson RJ, Kaltenborn WT, Burrows B. Single breath carbon 10.
monoxide trasfer factor in different forms of chronic airflow obstruction in a general population sample. Thorax 1990; 45: 514-19.
Activists, depending on their stance, will threaten
to use
against manufacturers who give offence by or by withholding an abortifacient product. supplying Abortion opponents have threatened a boycott of all products of manufacturers of antiprogestagens, and of products of their parent companies. Abortion rights supporters similarly pressured the Governor of Idaho with a boycott of that state’s agricultural products, particularly potatoes, and deterred him from signing anti-abortion market forces
legislation. Manufacturers should not succumb to the pressure from either direction. They should respect the plurality of views and make products available for use according to the judgment and conscience of patients and the health professionals. Their goal must continue to be the supply of scientifically proven products to doctors willing to supply services that their patients choose. A company that decides not to seek approval of a potentially safe and effective product that serves a legitimate need should respect market plurality by making the product available to other manufacturers--or surrender its rights. 1. Editorial. Mifepristone—contragestive agent or medical abortifacient? Lancet 1987; ii: 1308-10. 2. Gupta JK, Johnson N. Effect of mifepristone on the pregnant and non-pregnant cervix. Lancet 1990; 335: 1238-40. 3. Silvestre L, Dubois C, Renault M, Rezvani Y, Baulieu E-E, Ulmann A. Voluntary interruption of pregnancy with mifepristone (RU 486) and a prostaglandin analogue. A large-scale French experience. N Engl J Med 1990; 322: 645-48. 4. Rodger MW, Baird DT. Induction of therapeutic abortion in early pregnancy with mifepristone in combination with prostaglandin pessary. Lancet 1987; ii: 1415-18. 5. UK Multicentre Trial. The efficacy and tolerance of mifepristone and prostaglandin in first trimester termination of pregnancy. Br J Obstet Gynaecol 1990; 97: 480-86. 6. Anon. Mifepristone: application for UK licence. Lancet 1990; 336: 240. 7. McKenzie I. The potential effects on NHS resources. In: Williams C, ed. The abortion pill. London: Birth Control Trust, 1990: 41-47. 8. Cook RJ. Antiprogestin drugs: medical and legal issues. Fam Plann Perspect 1989; 21: 267-72.
the
haemoglobin available for measured carbon monoxide
uptake. A 1% increase in carbon monoxide saturation of haemoglobin will reduce the measured TLco by 1 %;9 since smokers may have up to 10% saturation of their haemoglobin, the relation of the test to smoking habit is important for interpretation of the results. TLco is reduced in anaemia and increased in polycythaemia. The constellation of dyspnoea, infiltrates on the chest radiograph, non-obstructive spirometric findings, and reduced lung volumes with a reduced TLco defines restrictive lung disease. These conditions include a group of interstitial disorders such as fibrosing alveolitis, sarcoidosis, asbestosis, farmer’s lung, connective tissue diseases, and polyarteritis nodosa. There is often associated hypoxaemia, because of alterations in ventilation and perfusion matching and not, as formerly thought, because of an alveolar block. In such disorders the TLco can be used as an indicator of progression and sometimes—eg, in sarcoidosis-as an indicator of the response to treatment, although this application is not universally accepted.lO Low values of TLco also occur in association with obstructive lung disease, especially when there is a nonuniform distribution of alveolar ventilation to perfusion, as in cystic fibrosis, and also in emphysema owing to a decrease in the gas exchange area. TLco can help to define subgroups of patients with airways obstruction. Knudson and colleagues lately described the relation between asthma and TLco in patients with obstructive airways disease.l TLC() was normal or increased in patients with asthma but reduced in patients with airways obstruction in whom asthma had not been diagnosed and who smoked. Pulmonary thromboembolic disorders also reduce TL, whereas pulmonary haemorrhage will increase the Kco because haemoglobin is sequestered in the alveolar compartment. Overall, TLco and Kco are subtle indicators of lung function; changes are not specific to individual disorders, although they can help in the diagnosis and management of parenchymal lung disease.
DIFFUSION CONFUSION Epidemiology standardisation project. Am Rev Respir Dis 1978; 118: 1-120. 2. Spicer WS, Johnson RL, Forster RE. Diffusing capacity and blood flow in different regions of the lung. J Appl Physiol 1962; 17: 587-95. 3. Filley GF, MacIntosh DJ, Wright GW. CO uptake and pulmonary diffusing capacity in normal subjects at rest and during exercise. J Clin Invest 1954; 33: 530-39. 4. Lewis BM, Lin T, Noe FE, Hayford-Welsing EJ. The measurement of pulmonary diffusing capacity for carbon monoxide by a rebreathing method. J Clin Invest 1959; 38: 2073-86. 5. Crapo RO, Morris AH, Gardener RM, Schaap RN. Computational techniques for rebreathing lung volume and pulmonary capillary blood flow. J Appl Physiol 1982; 52: 1375-77. 6. Knudson RJ, Kaltenborn WT, Knudson DE, Burrows B. The single-breath carbon monoxide diffusing capacity: reference equations derived from a healthy nonsmoking population and effects of hematocrit. Am Rev Respir Dis 1987; 135: 805-11. 7. Cadigan JB, Marks A, Ellicott MF, Jones RH, Gaensler EA. An analysis of factors affecting the measurement of pulmonary diffusing capacity by the single breath method. J Clin Invest 1961; 40: 1495-514. 8. Hyland RH, Krastins IRB, Aspin N, Mansell AL, Zanid N. Effect of body position on carbon monoxide diffusing capacity in asymptomatic smokers and nonsmokers. Am Rev Respir Dis 1978; 117: 1045-53. 9. Knudson RJ, Kaltenbom WT, Burrows B. The effects of cigarette smoking and smoking cessation on the carbon monoxide diffusing capacity of the lung in asymptomatic subjects. Am Rev Respir Dis 1989; 1. Ferns GB.
Oxygen diffuses from air in the alveolar space to haemoglobin in the red blood cell across a series of resistances-alveolar lining cells; lung interstitium; endothelial cells; a plasma layer; erythrocyte membrane; erythrocyte cytoplasm; and the haemoglobin molecule. Thus diffusion may be altered by changes in any of these Since diffusion of oxygen (D2) is difficult to for routine purposes carbon monoxide diffusion is measure, measured instead.l-4 However, there are differences between Dca and Doz because of the nature of the gases, concentration gradients, and binding characteristics of the gases to haemoglobin. Carbon monoxide diffusion is usually called transfer factor (TL,). The single-breath method, which is most commonly used, includes a measure of alveolar volume (VJ. The ratio TLco/VA or Kco indicates the quality of diffusion in ventilated alveoli. Technical factors (eg, breath-holding time and incorrect collection of alveolar gas) may affect TLco results. There are physiological variations in TLco according to gender and height; TLco also declines with age. Consequently, correction factors are usually applied and normal ranges and predicted values are used to aid interpretation.6 TL, increases with lung inflation,7 and in the supine posture owing to the effect of gravity on ventilation perfusion matching.8 Tobacco smoking reduces structures.
140: 645-51.
Ogilvie C. The single-breath carbon monoxide transfer test 25 years on: a reappraisal. 2-clinical considerations. Thorax 1983; 38: 5-9. 11. Knudson RJ, Kaltenborn WT, Burrows B. Single breath carbon 10.
monoxide trasfer factor in different forms of chronic airflow obstruction in a general population sample. Thorax 1990; 45: 514-19.
