981
seems ritualistic. Similarly, sticky mats can seem pointless unless they trap a large amount of soil, fluff, or dust. Such a mat that becomes dirty quickly is needed; if this does not happen the mat is unnecessary. The reason for rapid accumulation of dirt should be investigated-often the design of traffic flow, air flow, and theatre should be questioned. A sticky mat is an "extended corridor".
How much soil can be tolerated on the theatre floor? To test whether there is dispersion to table height, we must load the floor before doing the test. Hambraeus et al3 have demonstrated such dispersion. Does this matter? Does infection occur? Dr Heneghan (Jan 19, p 179) rightly states that there are few hard data to show the relation between design, procedures of transfer, dress, and infection rates in modem theatres. An important factor is the virulence and number of microorganisms allowed into the wound. I fear that most correspondents who question the design features and procedures that were instituted 20-30 years ago have not been exposed to the virulence of the "old-type" staphylococcus or the haemolytic streptococcus. Although I agree with their questioning of rituals, they must ensure that they do not become too blase and relax procedures unless they first thoroughly investigate all the associated
factors. Microbiology and Infectious Disease, Alfred Hospital, 3181 Melbourne, Australia
ALLAN PERCEVAL
1. Lewis DA, Weymont G, Nokes
CM, et al. A bacteriological study of the effect on the environment of using a one- or two-trolley system in theatre. J Hosp Infect 1990; 15: 35-53. 2. Ayliffe GAJ, Babb JR, Collins BJ, et al. Transfer areas and clean zones in operating
suites. J Hyg 1969, 67: 417-25. 3. Hambraeus A, Bengtsson S, Laurell G. Bacterial contamination in a modem operating suite 3: importance of floor contamination as a source of airborne bacteria. J Hyg 1978; 80: 169-74.
Criteria for
registering births
SiR,—Your Feb 9 editorial (p 331) emphasises the need for a new boundary between registrable and non-registrable births, to make mortality statistics more reliable. To estimate the consequences of new registration rules we calculated mortality rates using several registration limits in the same population. Data were derived from the medical records of two teaching hospitals in 1983 and 1984. In these two units registration of deliveries started at 20 weeks’ gestation. We used the following viability limits: (1) for all fetuses and infants, at least 500 g or, when birthweight was not available, gestational age of 22 weeks or more (World Health Organisation’s recommendation for national statistics); (2) for all fetuses and infants, at least 1000 g or, when birthweight was not available, gestational age of 28 weeks or more (WHO recommendation for international comparisons1); (3) for all fetuses and infants, at least 500 g or 22 weeks of gestation; (4) for all fetuses, at least 28 weeks’ gestational age and no registration limit for neonatal deaths (regulation for vital statistics in most European Community [EC] countries2). Figures based on the usual regulation in EC countries were very close to those based on the WHO recommendation for international comparisons (table). However, the perinatal mortality rate was 18-7 per 1000 (EC) and 27-3 per 1000 (WHO national). The major difference lay in stillbirths: the stillbirth rate according to the WHO national limit was twice as high as the rate according to the usual EC limit. These results are consistent with those observed by Hertoghe et al on hospital data in South Hainaut, Belgium.3 They illustrate the great variation in mortality rates when the registration limit is modified. In practice there is not such a clear-cut boundary between registered and non-registered births as the use of strict guidelines might imply. Under-reporting is frequent among very preterm or very-low-birthweight babies 3415 especially when doctors judge that they would not have been viable. Thus, moving from the actual registration to the WHO recommendation for national statistics might result in a larger increase in perinatal mortality than that recorded in the table . The registration limit recommended by WHO is based on
DEATHS AND RATES ACCORDING TO REGISTRATION LIMIT
birthweight, the main reason being that birthweight is more reliably recorded than gestational age. This argument is getting less important as ultrasound examinations are becoming routine. Furthermore, obstetricians are more interested in statistics based on age than in those based on birthweight because the former are useful criteria for medical decisions during pregnancy.6 To meet these needs registration should include all fetuses and infants weighing at least 500 g or having a gestational age of 22 weeks or more. In our population the perinatal mortality rate with this limit (28per 1000) was close to the one obtained with the WHO recommendation for national statistics (27-3). With this new registration limit it would also be possible to provide two sets of mortality rates-for fetuses and infants weighing 500 g or more and for fetuses and infants of 22 weeks of more.
gestational
INSERM U149, Maternal and Child Health
Epidemiological Research Unit Clinique Baudelocque, 123 blvd de Port-Royal, and
75014 Paris, France, and INSERM CJF 89-08, Biological and Clinical Research in and Hôpital de La Grave, Toulouse
BÉATRICE BLONDEL HÉLÈNE GRANDJEAN MONIQUE KAMINSKI GÉRARD BRÉAT GEORGES PONTONNIER Reproduction, CLAUDE SUREAU
1. WHO. International classification of diseases: 1975 revision. Geneva: WHO, 1977. 2. Blondel B, Bouvier-Colle M-H, Darchy P. Collecte et traitement des causes de décès dans les pays de la CEE. In: Kaminski M, Bouvier-Colle M-H, Blondel B, eds. Mortalité des jeunes dans le pays de la Communauté Européenne. Paris: INSERM-Doin, 1985. 3. Hertoghe L, De Wals P, Van Reempts P, Vincotte-Mols M, Borlee-Grimee I, Lechat MF. Problèmes de définition et de classification des décès périnatals. Rev Epidémiol Santé Publ 1986; 34: 161-67. 4. Keirse MJNC. Perinatal mortality rates do not contain what they purport to contain. Lancet 1984; i: 1166-69. 5. Doombos JPR, Nordbeck HJ, Treffers PE. The reliability of perinatal mortality statistics in the Netherlands. Am J Obstet Gynecol 1987; 156: 1183-87. 6. Working Group on the Very Low Birthweight Infant. European Community collaborative study of outcome of pregnancy between 22 and 28 weeks’ gestation. Lancet 1990; 336: 782-84.
Deprivation in infancy and risk of ischaemic heart disease SiR,—The geographical evidence does not persuade Dr BenShlomo and Dr Davey-Smith (March 2, p 530) that influences in fetal life and infancy determine risk of ischaemic heart disease. They recommend that longitudinal studies from infancy to adult life are done. Three such studies have been completed by this unit, and early findings reported.1,2 They provide further evidence that retardation of growth during critical periods of fetal and infant development has a major effect on cardiovascular disease. MRC Environmental Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton S09 4XY, UK
D.
J. P. BARKER
1. Ciba Foundation Symposium 156. The childhood environment and adult disease. Chichester: John Wiley, 1991. 2. Barker DJP. The intrauterine origins of cardiovascular and obstructive lung disease in adult life. J R Coll Phys Lond 1991; 25: 129-33.
Dehydration in dying patients SIR,-Dr Waller and his colleagues (March 23, p 745) ignore the practical reasons why intravenous fluids are rarely used in hospices. If people are fully hydrated just before they die, their bladders fill, causing either incontinence or distressing restlessness. Their
seems ritualistic. Similarly, sticky mats can seem pointless unless they trap a large amount of soil, fluff, or dust. Such a mat that becomes dirty quickly is needed; if this does not happen the mat is unnecessary. The reason for rapid accumulation of dirt should be investigated-often the design of traffic flow, air flow, and theatre should be questioned. A sticky mat is an "extended corridor".
How much soil can be tolerated on the theatre floor? To test whether there is dispersion to table height, we must load the floor before doing the test. Hambraeus et al3 have demonstrated such dispersion. Does this matter? Does infection occur? Dr Heneghan (Jan 19, p 179) rightly states that there are few hard data to show the relation between design, procedures of transfer, dress, and infection rates in modem theatres. An important factor is the virulence and number of microorganisms allowed into the wound. I fear that most correspondents who question the design features and procedures that were instituted 20-30 years ago have not been exposed to the virulence of the "old-type" staphylococcus or the haemolytic streptococcus. Although I agree with their questioning of rituals, they must ensure that they do not become too blase and relax procedures unless they first thoroughly investigate all the associated
factors. Microbiology and Infectious Disease, Alfred Hospital, 3181 Melbourne, Australia
ALLAN PERCEVAL
1. Lewis DA, Weymont G, Nokes
CM, et al. A bacteriological study of the effect on the environment of using a one- or two-trolley system in theatre. J Hosp Infect 1990; 15: 35-53. 2. Ayliffe GAJ, Babb JR, Collins BJ, et al. Transfer areas and clean zones in operating
suites. J Hyg 1969, 67: 417-25. 3. Hambraeus A, Bengtsson S, Laurell G. Bacterial contamination in a modem operating suite 3: importance of floor contamination as a source of airborne bacteria. J Hyg 1978; 80: 169-74.
Criteria for
registering births
SiR,—Your Feb 9 editorial (p 331) emphasises the need for a new boundary between registrable and non-registrable births, to make mortality statistics more reliable. To estimate the consequences of new registration rules we calculated mortality rates using several registration limits in the same population. Data were derived from the medical records of two teaching hospitals in 1983 and 1984. In these two units registration of deliveries started at 20 weeks’ gestation. We used the following viability limits: (1) for all fetuses and infants, at least 500 g or, when birthweight was not available, gestational age of 22 weeks or more (World Health Organisation’s recommendation for national statistics); (2) for all fetuses and infants, at least 1000 g or, when birthweight was not available, gestational age of 28 weeks or more (WHO recommendation for international comparisons1); (3) for all fetuses and infants, at least 500 g or 22 weeks of gestation; (4) for all fetuses, at least 28 weeks’ gestational age and no registration limit for neonatal deaths (regulation for vital statistics in most European Community [EC] countries2). Figures based on the usual regulation in EC countries were very close to those based on the WHO recommendation for international comparisons (table). However, the perinatal mortality rate was 18-7 per 1000 (EC) and 27-3 per 1000 (WHO national). The major difference lay in stillbirths: the stillbirth rate according to the WHO national limit was twice as high as the rate according to the usual EC limit. These results are consistent with those observed by Hertoghe et al on hospital data in South Hainaut, Belgium.3 They illustrate the great variation in mortality rates when the registration limit is modified. In practice there is not such a clear-cut boundary between registered and non-registered births as the use of strict guidelines might imply. Under-reporting is frequent among very preterm or very-low-birthweight babies 3415 especially when doctors judge that they would not have been viable. Thus, moving from the actual registration to the WHO recommendation for national statistics might result in a larger increase in perinatal mortality than that recorded in the table . The registration limit recommended by WHO is based on
DEATHS AND RATES ACCORDING TO REGISTRATION LIMIT
birthweight, the main reason being that birthweight is more reliably recorded than gestational age. This argument is getting less important as ultrasound examinations are becoming routine. Furthermore, obstetricians are more interested in statistics based on age than in those based on birthweight because the former are useful criteria for medical decisions during pregnancy.6 To meet these needs registration should include all fetuses and infants weighing at least 500 g or having a gestational age of 22 weeks or more. In our population the perinatal mortality rate with this limit (28per 1000) was close to the one obtained with the WHO recommendation for national statistics (27-3). With this new registration limit it would also be possible to provide two sets of mortality rates-for fetuses and infants weighing 500 g or more and for fetuses and infants of 22 weeks of more.
gestational
INSERM U149, Maternal and Child Health
Epidemiological Research Unit Clinique Baudelocque, 123 blvd de Port-Royal, and
75014 Paris, France, and INSERM CJF 89-08, Biological and Clinical Research in and Hôpital de La Grave, Toulouse
BÉATRICE BLONDEL HÉLÈNE GRANDJEAN MONIQUE KAMINSKI GÉRARD BRÉAT GEORGES PONTONNIER Reproduction, CLAUDE SUREAU
1. WHO. International classification of diseases: 1975 revision. Geneva: WHO, 1977. 2. Blondel B, Bouvier-Colle M-H, Darchy P. Collecte et traitement des causes de décès dans les pays de la CEE. In: Kaminski M, Bouvier-Colle M-H, Blondel B, eds. Mortalité des jeunes dans le pays de la Communauté Européenne. Paris: INSERM-Doin, 1985. 3. Hertoghe L, De Wals P, Van Reempts P, Vincotte-Mols M, Borlee-Grimee I, Lechat MF. Problèmes de définition et de classification des décès périnatals. Rev Epidémiol Santé Publ 1986; 34: 161-67. 4. Keirse MJNC. Perinatal mortality rates do not contain what they purport to contain. Lancet 1984; i: 1166-69. 5. Doombos JPR, Nordbeck HJ, Treffers PE. The reliability of perinatal mortality statistics in the Netherlands. Am J Obstet Gynecol 1987; 156: 1183-87. 6. Working Group on the Very Low Birthweight Infant. European Community collaborative study of outcome of pregnancy between 22 and 28 weeks’ gestation. Lancet 1990; 336: 782-84.
Deprivation in infancy and risk of ischaemic heart disease SiR,—The geographical evidence does not persuade Dr BenShlomo and Dr Davey-Smith (March 2, p 530) that influences in fetal life and infancy determine risk of ischaemic heart disease. They recommend that longitudinal studies from infancy to adult life are done. Three such studies have been completed by this unit, and early findings reported.1,2 They provide further evidence that retardation of growth during critical periods of fetal and infant development has a major effect on cardiovascular disease. MRC Environmental Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton S09 4XY, UK
D.
J. P. BARKER
1. Ciba Foundation Symposium 156. The childhood environment and adult disease. Chichester: John Wiley, 1991. 2. Barker DJP. The intrauterine origins of cardiovascular and obstructive lung disease in adult life. J R Coll Phys Lond 1991; 25: 129-33.
Dehydration in dying patients SIR,-Dr Waller and his colleagues (March 23, p 745) ignore the practical reasons why intravenous fluids are rarely used in hospices. If people are fully hydrated just before they die, their bladders fill, causing either incontinence or distressing restlessness. Their
