1025 studv. Some of these are methodological and one relates to the interpretation of the findings. Needleman et al. analysed the lead content of deciduous teeth of a large sample of 6-7-year-old children. The 10% of children with the highest and the 10% of children with the lowest lead levels were extensively studied with a battery of psychological tests. After statistical correction for social factors which favoured the "low lead" group, "high lead" children still did less well on most measures, in many cases to a statistically significant degree. Needleman et al. conclude "The impaired function of children with high lead ... appears to be an early adverse effect of exposure to lead". It still seems to me possible that children who were more disturbed and duller in intelligence for other reasons were more likely to have ingested lead-contaminated materials in their everyday activity. Needleman et al. offer in their paper no other explanation as to why the children varied in the lead content in their teeth. This issue is a difficult one to resolve. In the comments on the preliminary report of this study, it was suggested that differences between high and low lead groups could have been due to parental inattention/neglect. Dr Needleman suggests in his letter that this possibility is ruled out in the full paper, but this is not so. For example, high and low dentine lead groups are reported to be similar on "parental attitude" scores, but details of the reliability and validity of the measures used are not given. Parental attitude questionnaires are notoriously poor indicators of parental behaviour’ and with the available information it is difficult to know how similar the groups really were, for example, in the quality of parental stimulation, the consistency of parental discipline, and parental warmth and affection. All these factors affect intelligence or behaviour. These reservations are not trivial. The differences between the high and low lead groups, although significant, are small. For example, a 4.5point difference in W.I.S.C. full-scale i.Q. is significant at the 3% level even after a 3.11 point difference in parental i.Q. and a highly significant difference in paternal education in the same direction have been taken into account. It would not be surprising if differences in children’s intelligence of this magnitude were due to factors difficult to evaluate. Such doubts are compounded by the fact that only a small proportion of the children at risk were studied, thus raising the possibility that selection factors affected the results. For example, data are presented on only 58 (31%) of the 187 highlead children. Reasons are given in the paper for not including children in the study (bilingual home, parents not interested, and so on) and reasons are also given for assuming that those studied did not differ from non-studied children in teachers’ behaviour ratings. However, there is strong evidence to suggest that, in studies of this type, responders differ from non-responders to a much greater degree than has hitherto been thought,2 and, although non-response was only one reason for exclusion, the proportion of children at risk who were studied inevitably casts some doubt on the degree to which the findings can be generalised. I would like to end with a brief general observation on the relation between science and social policy. It is the main, though not the only, task of applied medical and social scientists to enhance understanding of problems so that sensible political decisions can be taken by others. It would be a pity, however, if my comments on the comprehensive paper by Needleman et al. were taken to imply any lack of concern on the issue of lead in the environment.

1

Yarrow,

31,131

a

used to describe a complex of symptoms, which may be observed in different pathological states. It manifests as extravasation of protein-rich fluid in the lungs, decreased pulmonary compliance, hypoxsemia, and "white lungs" on chest X-ray.’ The pathophysiology remains at issue, through shock and disseminated intravascular coagulation have been suggested as precipitating factors. Pulmonary oedema may be observed in acute salicylate poisoning and may be the cause of death.2-5 The clinical course in a patient we have seen suggests that a high concentration of salicylate may elicit the complex of symptoms described as A.R.D.s. and, that the pulmonary oedema observed in acute salicylate poisoning is of the type observed in conjunction with A.R.D.S. Consequently, the methods used in the treatment of A.R.D.S. should be applied to patients with pulmonary complications due to salicylate intoxication. A 54-year-old woman was admitted with pulmonary oedema. She had no history of cardiac disease, and E.C.G. on admission was normal. During the days before admission she had felt increasingly dyspnoeic. She had taken no medicines apart from acetylsalicylic acid (aspirin), ingested in large quantities for arthritic pain. On admission she had a metabolic acidosis (plasma-bicarbonate 12-6 mmol/1). The concentration of acetylsalicylic acid in plasma was 3-8 mmol/1, indicating that she had probably taken 10-20 g aspirin; normal doses of aspirin usually yield plasma concentrations below 0.5 mmol/1. She was severely hypoxxmic, and during the next 24 h Pa02 rose to only 48 mm Hg (6-4 kPa) despite administration of diuretics and subsequent treatment in a respirator with positive-pressure ventilation (Fpz=0.8) and 5 cm water peak end-expiratory pressure. A total ventilation of 14-16 1/min was needed to maintain PaCO2 within the normal range. The inflation pressures required were high (50-60 cm water) indicating a low pulmonary compliance. Chest X-ray showed white lungs characteristic of A.R.D.S. Her condition improved only slowly, and she had to be kept on a respirator for nearly 3 weeks. During the first week the thrombocyte-count and hxmoglobin concentration fell, and the laboratory findings indicated activation of the coagulation system. There was no apparent source of bleeding, and it could not be established whether coagulation had occurred intravascularly or extravascularly. 1 month after admission the patient could be transferred from intensive care to the department of physical rehabilitation. She is now in good health. This patient had symptoms and a clinical course which are characteristic of A.R.D.S. We could not find any cause of these symptoms, other than a high concentration of salicylate in blood on admission. This case suggests that salicylate poisoning may be one cause of A.R.D.S. Pulmonary oedema fluid in A.R.D.S. has a high protein content suggesting an increased pulmonary capillary permeability and indeed, acetylsalicylic acid has been shown to increase pulmonary capillary permeability.6 Pulmonary complications in patients with salicylate poisoning should be treated in the same way as A.R.D.S. from other

causes-i.e., by adding oxygen to inspired air, by ventilatory support with positive end-expiratory pressure or continuous positive airway pressure, and diuretics. The clearing of the protein-rich fluid from the or even weeks.

lung

interstitial space may take

days

SØREN C. SØRENSEN

PHILIP GRAHAM

M. R., Campbell, J. D., Burton, R. V. Child Rearing: an enquiry research methods. San Francisco, 1968. 2 Cox, A. D., Rutter, M., Yule, B. A., Quinton, D. Br. J. prev. soc. Med. 1977, into

SIR,-Adult respiratory-distress syndrome (A.R.D.S.) is term

Department of Anæsthesiology, Copenhagen Municipal Hospital, 1399 Copenhagen K, Denmark

Department

of Child Psychiatry, Institute of Child Health, Hospital for Sick Children, London WC1N 3JH

ADULT RESPIRATORY-DISTRESS SYNDROME IN SALICYLATE INTOXICATION

1. Sørensen, S C in Shock (edited by H. Skjoldborg), p. 31. Amsterdam, 1978. 2 Granville-Grossmann, K. L., Sergeant, H. G. S. Lancet, 1960, i, 575 3. Proudfott, A. T , Brown, S. S. Br med. J. 1969, ii, 547 4 Davis, P R, Burch, R E Ann. intern. Med 1974, 80, 553. 5. Andersen, R , Refstad, S Intens Care Med. 1978, 4, 211. 6. Bowets, R. E., and others. Am Rev. resp. Dis. 1977, 115, 261.

Adult respiratory-distress syndrome in salicylate intoxication.

1025 studv. Some of these are methodological and one relates to the interpretation of the findings. Needleman et al. analysed the lead content of deci...
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