674
in the Netherlands. Health Policy 1987; 8: 197-206. 3. Gevers JKM. Legal developments concerning active euthanasia on request in the Netherlands. Bioethics 1987; 1: 156-62. 4. Fenigsen R. Mercy, murder and morality perspectives on euthanasia: a case against Dutch euthanasia. Hastings Center Rep 1989; 19: 22-30. 5. van der Maas PJ, van Delden JJM, Pijnenborg L. Medical decisions concerning the end of life (in Dutch). The Hague: Staatsuitgeverij, 1991. 6. Commission on the Study of Medical Practice concerning Euthanasia. Medical decisions concerning the end of life (in Dutch). The Hague: Staatsuitgeverij, 1991. 7. Central Bureau of Statistics. The end of life in medical practice (in Dutch). The Hague: Staatsuitgeverij, 1991. 8. Bartelds AIM, Fracheboud J, van der Zee J. The Dutch sentinel practice network: relevance for public health policy. Utrecht: NIVEL, 1989; 259-83. 9. Oliemans AP, Nijhuis HGJ. Euthanasie in de huisartsenpraktijk. Med Contact 1986; 41: 691. 10. Schudel WJ. Euthanasie (verzoek). Epidemiol Bull GG&GD 1987 (May). The Hague: GG&GD, 1987. 11. GG&GD. Amersterdams peilstationproject (annual report, 1986). Amsterdam: GG&GD, 1987. 12. van der Wal G, van Eijk JThM, Leenen HJJ, Spreeuwenberg C. Euthanasie en hulp bij zelfdoding in de huisartsenpraktijk. Med Contact 1991; 46: 174-76. 13. Kuhse H. Voluntary euthanasia in the Netherlands. Med J Aust 1987;
process about euthanasia, had benefited from the public discussion in the Netherlands. MDEL should receive increasing attention in research, in teaching, and in public debate. An open discussion which starts from the premise that MDEL are being taken and have to be taken in any
country with high standards of medical care and with an involved medical profession, will contribute to a better quality care for the dying. This study was funded by the Dutch Ministry of Justice and the Ministry of Welfare, Health and Culture. We thank the thousands of Dutch physicians who provided information for this study, the Royal Dutch Medical Association, and the Chief Inspector of Health. We also thank the following for their invaluable help: Department of Public Health and Social Medicine. M. C. M. van den Akker, G. J. Bonsel, A. E. de Bruyn, J. M. Eimers, A. F. C. Gerritsen, A. G. Griffioen-Kisjes, J. D. F. Habbema, M. J. P. van Hooft, H. M. van Lamoen, J. P. Mackenbach, H. G. M. Rigter, D. R. Le Sage, Th.E. van der Starre-Bout, K. A. M. Wissink. Central Bureau of Statistics: W. Begeer, J. T. P. Bonte, L. M. Friden-Kill, J. J. Glerum, A. Z. Israels, W. A. M. de Jong, J. W. P. F. Kardaun, P. Kooiman, M. F. P. van der Poel, S. J. M. de Ree, E. van der Schoor, E. J. M. van der Splinter, H. K. van Tuinen, P. de Wolf. Commission of Inquiry into Medical Practice with Regard to Euthanasia: E. Borst-Eilers, D. van Dijk, W. H. B. den Hartog Jager, A. Kors, S. A. de Lange, J. van Londen, J. J. M. Michels, J. Remmelink, T. M. Schalken, C. J. M. Schuyt. And J. J. C. Pieters, C. Spreeuwenberg, B. A. van Hout, A. B. Leussink, P. G. H. Mulder, W. Tijssen, J. B. Verouden, F. C. B. van
147: 394-96. 14. Angell M. Euthanasia. N Engl J Med 1988; 319: 1348-50. 15. British Medical Association. Euthanasia. London: BMA, 1988. 16. Vos M. Toetsing bij euthanasie. Med Contact 1985; 40: 1059-60. 17. Neu S, Kjellstrand CM. Stopping long-term dialysis: an empirical study of withdrawal of life-supporting treatment. N Engl J Med 314: 14-20. 18. Smedira NG, Evans BH, Grais LS, et al. Withholding and withdrawal of life support from the critically ill. N Engl J Med 1990; 322: 309-15. 19. Brown NK, Thompson DJ. Nontreatment of fever in extended-care facilities. N Engl J Med 1979; 300: 1246-50.
Wijmen. REFERENCES
Rigter HGM. Euthanasia in the Netherlands: distinguishing facts from fiction. Hastings Center Rep 1989; 19: 31-32. 2. Leenen HJJ. Euthanasia, assistance to suicide and the law: developments 1.
Urine collection from
Urine was collected for microscopy and culture by standard use of sterile adhesive bags and by extraction from wet disposable nappies from 45 patients aged 1 to 23 months. Urine can readily be obtained by compression of wet nappy fibres within a 20 ml syringe if highly absorbent brands that contain gel beads are avoided. Red and white cell numbers were reduced on light microscopy of specimens obtained from nappies, but bacterial counts were unchanged. On culture, 6 children were shown to have urinary tract infections by both methods; of the children who did not have a urine infection, the contamination rate was lower from nappy collections (10/39 vs 17/39 from urine bags). Biochemical analysis of urine collected from 11 older children showed very close correlation for sodium, potassium, urea, and creatinine concentrations and osmolality between freshly voided urine and samples obtained after they were soaked into disposable nappies for 3 h and reclaimed, although there was greater variation for measurements of calcium and phosphate. Extraction of urine from disposable nappies put on within 4 h and which are not soiled by faeces is an inexpensive, rapid, and simple method to collect urine from young children for culture, microscopy for bacteria, and biochemical analysis.
disposable nappies
Introduction Examination of a urine sample should be an integral part of clinical assessment in paediatric practice because of the diversity of symptoms among children with urinary tract infection. Although midstream specimens are easily obtained from older children, urine is usually collected from infants in sterile adhesive bags. This technique has drawbacks: bags may not adhere adequately; the adhesive may cause discomfort, particularly for children with skin disorders; and, in the UK, such collection bags are not prescribable and many general practitioners are reluctant to provide them because of their cost. Urine obtained from cotton-wool balls held within disposable nappies can be used for the measurement of several of its constituents.! This technique is simple and overcomes some of the problems associated with the use of adhesive bags. We investigated whether it was possible to obtain more information, including collection for microscopy and culture, by retrieval of urine from the fibre padding of the disposable nappies themselves.
ADDRESSES: Department of Child Health (T. Ahmad, MRCP, D Vickers, MRCP, S Campbell, BNurs, M. G Coulthard, FRCP), and Department of Microbiology (S Pedler, MRCPath), Royal Victoria Infirmary, Newcastle upon Tyne, UK. Correspondence to Dr M.G Coulthard, Department of Child Health, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK.
675
Methods Urine samples were obtained for microscopy and culture from 45 infants aged 1 to 23 months, with a wide range of symptoms, who were seen in outpatient clinics or who had been admitted to hospital. Urine was collected from each child by use of standard urine collection bags and from disposable nappies. Before application of urine bags the skin was cleaned with chlorhexidine wipes; the times at which the bag was put on and the urine collected were recorded. Disposable nappies were put on by parents according to their normal routine, with no specific instructions given about cleaning of the perineum. In many cases we simply used the nappy that the infant was wearing on arrival. The make of the nappy was noted and the times at which it was put on and the sample taken were recorded; nappies that had been on for longer than 4 h and those soiled with faeces were excluded. For extraction of urine the nappy lining layer was tom away and the damp fibres pushed into the barrel of a standard 20 ml disposable syringe from which the plunger had been removed; urine is readily obtained by replacement of the plunger and compression of the fibres. However, it was immediately apparent that the ultra-absorbent types of nappies which contain gel were unsuitable because extraction of urine was often impossible and samples frequently contained gel-like material, and such nappies were not used in this investigation. Half of each sample obtained was sent to a laboratory for routine culture on MacConkey and blood agar plates, and the other half was examined by light microscopy within 2 h of collection (by T. A. or M. G. C.) on a ’Labophot’ (Nikon, Tokyo, Japan) microscope with phase contrast and a Neubaur counting chamber (’Crystalite’, Hawksley, Lancing, West Sussex, UK) with a mirrored surface. Each specimen was examined and scored for red and white blood cells, epithelial cells, crystals, debris, and bacteria. To determine whether the material of the nappy might inhibit bacterial growth, broth cultures of representative bacteria (Escherichia coli and Streptococcus faecalis) were prepared and diluted in sterile physiological saline to an approximate initial count of 106 organisms/ml. 20 ml of this solution were inoculated onto 6 nappies which were incubated at 37°C. Specimens were reclaimed from the lining at hourly intervals for 6 h by the above technique. Midstream samples from 11 children aged 10-14 years were used to investigate possible use of urine collected from disposable nappies for biochemical analysis. 10 ml of the sample was retained for direct analysis, and the remainder (15-75 ml) was poured onto a disposable nappy and left at room temperature for 3 h and reclaimed as described above. Both samples were analysed for sodium, potassium, urea, creatinine, calcium, and phosphate by standard
u
14U
u
su
Fig 1-Linear
unne
concentration
(mmol/l)
regression plots of urinary constituent concentrations in nappy against bag urine samples.
I u
15 t)
(mmol/I)
Fig 2-Bland-Altman plots of bag minus nappy concentrations against mean urine concentrations.
autoanalyser techniques; osmolality point depression.
was
measured
urine
by freezing-
Results Extraction of urine with
a
syringe from fibrealways simple and effective 20 ml
padded disposable nappies procedure. 37 of 45 (82%) urine cultures showed complete agreement between samples collected by the two techniques (22 sterile urines, 9 with mixed growth, and 6 with more than 105 colony forming units [CFU]ml of the same single organism). For 7 infants mixed growth was obtained from the bag specimen when that collected from the disposable nappy was sterile; on no occasion did the nappy sample show a mixed growth when the bag sample was sterile. For 1 infant both samples showed more than 105 CFU/ml of different organisms; repeat specimens without treatment were sterile on culture. On incubation of nappies soaked with the test bacterial solution, counts of viable organisms on the fluid obtained showed no change over 6 h, when compared with the original suspension, which indicated that the nappy material was not toxic to the organisms studied. Bacterial counts on light microscopy were identical for matched specimens obtained by the two collection techniques. However, much more debris in the form of cotton fibres was seen in urine obtained from the disposable nappies. Specimens obtained from disposable nappies had was
Bag
::>
Mean urine concentration
a
strikingly lower white cell counts than those collected from bags. For the 5 patients with white cell counts above
urine
676
50/mm3 (50 000/ml) in urine samples obtained by either technique, counts/mm3 (bag vs nappy) were 750 vs 0, 90 vs 10, 500 vs 220, 500 vs 20, and 70 vs 0. To investigate this difference further, urine that contained large numbers of
erythrocytes and white blood cells was poured onto a nappy and left at room temperature for 3 h. Microscopic examination of the extracted urine showed an 8-fold drop in both cell counts, which indicates retention or lysis of the cells by the nappy material. The results of biochemical analysis of urinary constituents from midstream urine specimens before and after retrieval from disposable nappies are shown in the figures. Fig 1 shows linear regression plots: correlation coefficients (r) were 0-999 for sodium, 0-997 for potassium, 0-999 for creatinine, 0-999 for osmolality, 0-999 for urea, 0-997 for phosphate, and 0-978 for calcium (all p < 0-001). Fig 2 shows Bland-Altman2 plots, which compare the differences between the methods (y axis) against the mean of the two methods (x axis), with results expressed as bias (mean difference) and limits of agreement (mean difference ± 2 SD). In general there was good agreement between concentrations measured in fresh and recovered urine, with values of bias from the Bland-Altman plots of approximately 0; the largest variations were seen for calcium and phosphate concentrations, and urine from nappies may be unsuitable for measurement of these constituents. Discussion Culture results from urine specimens obtained from
padded disposable nappies showed that children with urinary tract infections were correctly identified, and that most children without infections had sterile samples. Contaminated samples that gave a mixed growth of organisms or less than 10s CFU/ml of one species were seen with both types of urine collection, but were almost twice as
bag collections compared with nappy samples (17/45 vs 10/45, respectively). As urine passed into a bag will wash repeatedly over the perineum, whereas urine voided into a nappy rapidly passes through the surface layer to remain in deeper fibres which are not in contact with the skin, this finding may be less surprising than it first appears. On light microscopy of urine obtained by both techniques, erythrocyte and leucocyte counts were much lower, and therefore unreliable, in nappy samples, but bacterial counts, which may be more helpful for diagnosis of urine infections in children,3were not altered. Urine specimens collected from disposable nappies are also usable for the measurement of most commonly analysed biochemical constituents (with the probable exception of calcium and phosphate) and of osmolality. Our findings indicate that urine collection from a padded (not ultra-absorbent) disposable nappy which has been common
from
for less than 4 h and is not soiled with faeces is a convenient and, for most urinary constituents, an accurate alternative to collection in urine bags. This novel technique is simple, non-invasive, rapid, and inexpensive (in the UK the cost of a 20 ml syringe is less than a tenth of the cost of a urine bag); it should be particularly useful in hospital and outpatient departments and general practitioners’ surgeries, and for domiciliary visits-indeed, the specimen may often worn
arrive with the
patient. REFERENCES
SB, Lucas A. A nappy collection method for measuring urinary constituents and 24-hour urine output in infants. Arch Dis Child 1985; 60: 1018-20. 2. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; i: 307-10. 3. Vickers D, Ahmad T, Coulthard MG. Diagnosis of urinary tract infection in children: fresh urine microscopy or culture? Lancet (in 1. Roberts
press).
Critical incidents in the intensive therapy unit
Preventable mishaps in an intensive therapy unit were studied over 12 months by the critical incident technique. Staff were encouraged to complete confidential questionnaires describing incidents in which they had participated or had observed. This allowed classification of the events and examination of the views of staff on causes, detection, and prevention. 110 (80%) of 137 events were felt to have been due to human error; the remainder were due to equipment failure. Inexperience with equipment and shortage of trained staff were the factors most often felt to contribute to incidents. The critical incident technique is a useful way of improving standards of clinical care.
Introduction The critical incident technique was developed by Flanagan and others in the 1940s and was shown to be useful in the investigation of aircraft accidents. By examining factors responsible for an accident, the technique
draws attention to certain critical incidents that have an observable effect on the course of events. The technique has been widely appliedand we wondered whether it could be helpful in investigating mishaps in an intensive therapy unit
(ITU). We based our study on investigations of anaesthetic mishaps.3A critical incident was defined as an occurrence that could have led (if not discovered or corrected in time), or did lead, to an undesirable outcome. The incident had to involve an error by a member of staff or a failure of equipment. It had to have occurred while a patient was under the care of ITU staff but not necessarily within the ITU. The incident had to be describable in detail by a participant or observer and it had to be clearly preventable.
Methods We used a questionnaire based on one developed by Williamson and colleagues.’ The questionnaire asked staff to describe the ADDRESS: Intensive Therapy Unit, Western General Hospital, Edinburgh EH4 2XU, UK (D. Wright, FCAnaes, S. J. Mackenzie, FCAnaes, I. Buchan, RGN, Dip N, C. S. Cairns, RGN, L. E. Price, RGN) Correspondence to Dr David Wright.
in the Netherlands. Health Policy 1987; 8: 197-206. 3. Gevers JKM. Legal developments concerning active euthanasia on request in the Netherlands. Bioethics 1987; 1: 156-62. 4. Fenigsen R. Mercy, murder and morality perspectives on euthanasia: a case against Dutch euthanasia. Hastings Center Rep 1989; 19: 22-30. 5. van der Maas PJ, van Delden JJM, Pijnenborg L. Medical decisions concerning the end of life (in Dutch). The Hague: Staatsuitgeverij, 1991. 6. Commission on the Study of Medical Practice concerning Euthanasia. Medical decisions concerning the end of life (in Dutch). The Hague: Staatsuitgeverij, 1991. 7. Central Bureau of Statistics. The end of life in medical practice (in Dutch). The Hague: Staatsuitgeverij, 1991. 8. Bartelds AIM, Fracheboud J, van der Zee J. The Dutch sentinel practice network: relevance for public health policy. Utrecht: NIVEL, 1989; 259-83. 9. Oliemans AP, Nijhuis HGJ. Euthanasie in de huisartsenpraktijk. Med Contact 1986; 41: 691. 10. Schudel WJ. Euthanasie (verzoek). Epidemiol Bull GG&GD 1987 (May). The Hague: GG&GD, 1987. 11. GG&GD. Amersterdams peilstationproject (annual report, 1986). Amsterdam: GG&GD, 1987. 12. van der Wal G, van Eijk JThM, Leenen HJJ, Spreeuwenberg C. Euthanasie en hulp bij zelfdoding in de huisartsenpraktijk. Med Contact 1991; 46: 174-76. 13. Kuhse H. Voluntary euthanasia in the Netherlands. Med J Aust 1987;
process about euthanasia, had benefited from the public discussion in the Netherlands. MDEL should receive increasing attention in research, in teaching, and in public debate. An open discussion which starts from the premise that MDEL are being taken and have to be taken in any
country with high standards of medical care and with an involved medical profession, will contribute to a better quality care for the dying. This study was funded by the Dutch Ministry of Justice and the Ministry of Welfare, Health and Culture. We thank the thousands of Dutch physicians who provided information for this study, the Royal Dutch Medical Association, and the Chief Inspector of Health. We also thank the following for their invaluable help: Department of Public Health and Social Medicine. M. C. M. van den Akker, G. J. Bonsel, A. E. de Bruyn, J. M. Eimers, A. F. C. Gerritsen, A. G. Griffioen-Kisjes, J. D. F. Habbema, M. J. P. van Hooft, H. M. van Lamoen, J. P. Mackenbach, H. G. M. Rigter, D. R. Le Sage, Th.E. van der Starre-Bout, K. A. M. Wissink. Central Bureau of Statistics: W. Begeer, J. T. P. Bonte, L. M. Friden-Kill, J. J. Glerum, A. Z. Israels, W. A. M. de Jong, J. W. P. F. Kardaun, P. Kooiman, M. F. P. van der Poel, S. J. M. de Ree, E. van der Schoor, E. J. M. van der Splinter, H. K. van Tuinen, P. de Wolf. Commission of Inquiry into Medical Practice with Regard to Euthanasia: E. Borst-Eilers, D. van Dijk, W. H. B. den Hartog Jager, A. Kors, S. A. de Lange, J. van Londen, J. J. M. Michels, J. Remmelink, T. M. Schalken, C. J. M. Schuyt. And J. J. C. Pieters, C. Spreeuwenberg, B. A. van Hout, A. B. Leussink, P. G. H. Mulder, W. Tijssen, J. B. Verouden, F. C. B. van
147: 394-96. 14. Angell M. Euthanasia. N Engl J Med 1988; 319: 1348-50. 15. British Medical Association. Euthanasia. London: BMA, 1988. 16. Vos M. Toetsing bij euthanasie. Med Contact 1985; 40: 1059-60. 17. Neu S, Kjellstrand CM. Stopping long-term dialysis: an empirical study of withdrawal of life-supporting treatment. N Engl J Med 314: 14-20. 18. Smedira NG, Evans BH, Grais LS, et al. Withholding and withdrawal of life support from the critically ill. N Engl J Med 1990; 322: 309-15. 19. Brown NK, Thompson DJ. Nontreatment of fever in extended-care facilities. N Engl J Med 1979; 300: 1246-50.
Wijmen. REFERENCES
Rigter HGM. Euthanasia in the Netherlands: distinguishing facts from fiction. Hastings Center Rep 1989; 19: 31-32. 2. Leenen HJJ. Euthanasia, assistance to suicide and the law: developments 1.
Urine collection from
Urine was collected for microscopy and culture by standard use of sterile adhesive bags and by extraction from wet disposable nappies from 45 patients aged 1 to 23 months. Urine can readily be obtained by compression of wet nappy fibres within a 20 ml syringe if highly absorbent brands that contain gel beads are avoided. Red and white cell numbers were reduced on light microscopy of specimens obtained from nappies, but bacterial counts were unchanged. On culture, 6 children were shown to have urinary tract infections by both methods; of the children who did not have a urine infection, the contamination rate was lower from nappy collections (10/39 vs 17/39 from urine bags). Biochemical analysis of urine collected from 11 older children showed very close correlation for sodium, potassium, urea, and creatinine concentrations and osmolality between freshly voided urine and samples obtained after they were soaked into disposable nappies for 3 h and reclaimed, although there was greater variation for measurements of calcium and phosphate. Extraction of urine from disposable nappies put on within 4 h and which are not soiled by faeces is an inexpensive, rapid, and simple method to collect urine from young children for culture, microscopy for bacteria, and biochemical analysis.
disposable nappies
Introduction Examination of a urine sample should be an integral part of clinical assessment in paediatric practice because of the diversity of symptoms among children with urinary tract infection. Although midstream specimens are easily obtained from older children, urine is usually collected from infants in sterile adhesive bags. This technique has drawbacks: bags may not adhere adequately; the adhesive may cause discomfort, particularly for children with skin disorders; and, in the UK, such collection bags are not prescribable and many general practitioners are reluctant to provide them because of their cost. Urine obtained from cotton-wool balls held within disposable nappies can be used for the measurement of several of its constituents.! This technique is simple and overcomes some of the problems associated with the use of adhesive bags. We investigated whether it was possible to obtain more information, including collection for microscopy and culture, by retrieval of urine from the fibre padding of the disposable nappies themselves.
ADDRESSES: Department of Child Health (T. Ahmad, MRCP, D Vickers, MRCP, S Campbell, BNurs, M. G Coulthard, FRCP), and Department of Microbiology (S Pedler, MRCPath), Royal Victoria Infirmary, Newcastle upon Tyne, UK. Correspondence to Dr M.G Coulthard, Department of Child Health, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK.
675
Methods Urine samples were obtained for microscopy and culture from 45 infants aged 1 to 23 months, with a wide range of symptoms, who were seen in outpatient clinics or who had been admitted to hospital. Urine was collected from each child by use of standard urine collection bags and from disposable nappies. Before application of urine bags the skin was cleaned with chlorhexidine wipes; the times at which the bag was put on and the urine collected were recorded. Disposable nappies were put on by parents according to their normal routine, with no specific instructions given about cleaning of the perineum. In many cases we simply used the nappy that the infant was wearing on arrival. The make of the nappy was noted and the times at which it was put on and the sample taken were recorded; nappies that had been on for longer than 4 h and those soiled with faeces were excluded. For extraction of urine the nappy lining layer was tom away and the damp fibres pushed into the barrel of a standard 20 ml disposable syringe from which the plunger had been removed; urine is readily obtained by replacement of the plunger and compression of the fibres. However, it was immediately apparent that the ultra-absorbent types of nappies which contain gel were unsuitable because extraction of urine was often impossible and samples frequently contained gel-like material, and such nappies were not used in this investigation. Half of each sample obtained was sent to a laboratory for routine culture on MacConkey and blood agar plates, and the other half was examined by light microscopy within 2 h of collection (by T. A. or M. G. C.) on a ’Labophot’ (Nikon, Tokyo, Japan) microscope with phase contrast and a Neubaur counting chamber (’Crystalite’, Hawksley, Lancing, West Sussex, UK) with a mirrored surface. Each specimen was examined and scored for red and white blood cells, epithelial cells, crystals, debris, and bacteria. To determine whether the material of the nappy might inhibit bacterial growth, broth cultures of representative bacteria (Escherichia coli and Streptococcus faecalis) were prepared and diluted in sterile physiological saline to an approximate initial count of 106 organisms/ml. 20 ml of this solution were inoculated onto 6 nappies which were incubated at 37°C. Specimens were reclaimed from the lining at hourly intervals for 6 h by the above technique. Midstream samples from 11 children aged 10-14 years were used to investigate possible use of urine collected from disposable nappies for biochemical analysis. 10 ml of the sample was retained for direct analysis, and the remainder (15-75 ml) was poured onto a disposable nappy and left at room temperature for 3 h and reclaimed as described above. Both samples were analysed for sodium, potassium, urea, creatinine, calcium, and phosphate by standard
u
14U
u
su
Fig 1-Linear
unne
concentration
(mmol/l)
regression plots of urinary constituent concentrations in nappy against bag urine samples.
I u
15 t)
(mmol/I)
Fig 2-Bland-Altman plots of bag minus nappy concentrations against mean urine concentrations.
autoanalyser techniques; osmolality point depression.
was
measured
urine
by freezing-
Results Extraction of urine with
a
syringe from fibrealways simple and effective 20 ml
padded disposable nappies procedure. 37 of 45 (82%) urine cultures showed complete agreement between samples collected by the two techniques (22 sterile urines, 9 with mixed growth, and 6 with more than 105 colony forming units [CFU]ml of the same single organism). For 7 infants mixed growth was obtained from the bag specimen when that collected from the disposable nappy was sterile; on no occasion did the nappy sample show a mixed growth when the bag sample was sterile. For 1 infant both samples showed more than 105 CFU/ml of different organisms; repeat specimens without treatment were sterile on culture. On incubation of nappies soaked with the test bacterial solution, counts of viable organisms on the fluid obtained showed no change over 6 h, when compared with the original suspension, which indicated that the nappy material was not toxic to the organisms studied. Bacterial counts on light microscopy were identical for matched specimens obtained by the two collection techniques. However, much more debris in the form of cotton fibres was seen in urine obtained from the disposable nappies. Specimens obtained from disposable nappies had was
Bag
::>
Mean urine concentration
a
strikingly lower white cell counts than those collected from bags. For the 5 patients with white cell counts above
urine
676
50/mm3 (50 000/ml) in urine samples obtained by either technique, counts/mm3 (bag vs nappy) were 750 vs 0, 90 vs 10, 500 vs 220, 500 vs 20, and 70 vs 0. To investigate this difference further, urine that contained large numbers of
erythrocytes and white blood cells was poured onto a nappy and left at room temperature for 3 h. Microscopic examination of the extracted urine showed an 8-fold drop in both cell counts, which indicates retention or lysis of the cells by the nappy material. The results of biochemical analysis of urinary constituents from midstream urine specimens before and after retrieval from disposable nappies are shown in the figures. Fig 1 shows linear regression plots: correlation coefficients (r) were 0-999 for sodium, 0-997 for potassium, 0-999 for creatinine, 0-999 for osmolality, 0-999 for urea, 0-997 for phosphate, and 0-978 for calcium (all p < 0-001). Fig 2 shows Bland-Altman2 plots, which compare the differences between the methods (y axis) against the mean of the two methods (x axis), with results expressed as bias (mean difference) and limits of agreement (mean difference ± 2 SD). In general there was good agreement between concentrations measured in fresh and recovered urine, with values of bias from the Bland-Altman plots of approximately 0; the largest variations were seen for calcium and phosphate concentrations, and urine from nappies may be unsuitable for measurement of these constituents. Discussion Culture results from urine specimens obtained from
padded disposable nappies showed that children with urinary tract infections were correctly identified, and that most children without infections had sterile samples. Contaminated samples that gave a mixed growth of organisms or less than 10s CFU/ml of one species were seen with both types of urine collection, but were almost twice as
bag collections compared with nappy samples (17/45 vs 10/45, respectively). As urine passed into a bag will wash repeatedly over the perineum, whereas urine voided into a nappy rapidly passes through the surface layer to remain in deeper fibres which are not in contact with the skin, this finding may be less surprising than it first appears. On light microscopy of urine obtained by both techniques, erythrocyte and leucocyte counts were much lower, and therefore unreliable, in nappy samples, but bacterial counts, which may be more helpful for diagnosis of urine infections in children,3were not altered. Urine specimens collected from disposable nappies are also usable for the measurement of most commonly analysed biochemical constituents (with the probable exception of calcium and phosphate) and of osmolality. Our findings indicate that urine collection from a padded (not ultra-absorbent) disposable nappy which has been common
from
for less than 4 h and is not soiled with faeces is a convenient and, for most urinary constituents, an accurate alternative to collection in urine bags. This novel technique is simple, non-invasive, rapid, and inexpensive (in the UK the cost of a 20 ml syringe is less than a tenth of the cost of a urine bag); it should be particularly useful in hospital and outpatient departments and general practitioners’ surgeries, and for domiciliary visits-indeed, the specimen may often worn
arrive with the
patient. REFERENCES
SB, Lucas A. A nappy collection method for measuring urinary constituents and 24-hour urine output in infants. Arch Dis Child 1985; 60: 1018-20. 2. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; i: 307-10. 3. Vickers D, Ahmad T, Coulthard MG. Diagnosis of urinary tract infection in children: fresh urine microscopy or culture? Lancet (in 1. Roberts
press).
Critical incidents in the intensive therapy unit
Preventable mishaps in an intensive therapy unit were studied over 12 months by the critical incident technique. Staff were encouraged to complete confidential questionnaires describing incidents in which they had participated or had observed. This allowed classification of the events and examination of the views of staff on causes, detection, and prevention. 110 (80%) of 137 events were felt to have been due to human error; the remainder were due to equipment failure. Inexperience with equipment and shortage of trained staff were the factors most often felt to contribute to incidents. The critical incident technique is a useful way of improving standards of clinical care.
Introduction The critical incident technique was developed by Flanagan and others in the 1940s and was shown to be useful in the investigation of aircraft accidents. By examining factors responsible for an accident, the technique
draws attention to certain critical incidents that have an observable effect on the course of events. The technique has been widely appliedand we wondered whether it could be helpful in investigating mishaps in an intensive therapy unit
(ITU). We based our study on investigations of anaesthetic mishaps.3A critical incident was defined as an occurrence that could have led (if not discovered or corrected in time), or did lead, to an undesirable outcome. The incident had to involve an error by a member of staff or a failure of equipment. It had to have occurred while a patient was under the care of ITU staff but not necessarily within the ITU. The incident had to be describable in detail by a participant or observer and it had to be clearly preventable.
Methods We used a questionnaire based on one developed by Williamson and colleagues.’ The questionnaire asked staff to describe the ADDRESS: Intensive Therapy Unit, Western General Hospital, Edinburgh EH4 2XU, UK (D. Wright, FCAnaes, S. J. Mackenzie, FCAnaes, I. Buchan, RGN, Dip N, C. S. Cairns, RGN, L. E. Price, RGN) Correspondence to Dr David Wright.
