1023 in the hours immediately after the accident. A which will give an immediate result while needed is test is still in the accident-and-emergency departthe patient et al. 12 have advocated testing serumment. Champion which correlates closely with blood-alcohol. osmolality, the time taken to perform the test short They emphasise It is whether this offers any advandebatable (2 min). a test. The difference in time (2 blood-alcohol over tage and min for blood-alcohol) for 30 min serum-osmolality be more than real for the serum-osmolaapparent may takes 30 min to reach the required about lity apparatus in a state of readiif not kept permanent temperature ness. Both tests normally require a trained technician. There may be advantages for very seriously injured patients in having both readings. A paper dipstick test would probably be accurate enough for immediate diagnosis and treatment of many patients, with a more accurate report from the laboratory confirming this on the following morning. Until reliable clinical tests are found, good patient care demands a laboratory test with an immediate report.

mostly

Fig.

1-Seasonal variation of temperature and

humidity

in

Zaria, Nigeria.

and the beginning of the rains. This report describes study of whether this was a real seasonal variation and also whether or not it was peculiar to P.P.C.F.

son

our

Patients, Methods, and Seasons Studied Zaria lies at latitude 111North and has pronounced seaWhen the rains end in October it is hot and humid at first but the temperature falls in November when a cold dry wind, the harmattan, begins to blow from the Sahara. The lowest temperature and humidity are reached at the end of December and in early January. When the harmattan stops blowing, usually in February, the temperature and the humidity rise. Sporadic heavy rainfall heralds the rainy season in April and May. It is extremely hot at this time and also humid. The temperature during the rainy season moves within a relatively narrow range. These major seasonal changes in temperature, humidity, and rainfall are shown in fig. 1. We first made a prospective study of 224 patients admitted to Ahmadu Bello University Hospital, Zaria, with P.P.C.F. from March, 1969, to March, 1972. P.P.C.F. was defined as cardiac failure occurring within six months of childbirth, but without any recognisable cause. Symptoms began within the first four weeks of delivery in over 50% of our patients. In our second study, we reviewed the admissions for all types of cardiac failure, in men and women, from July, 1972, to June, 1975. During this three-year period, we also compared our patients with the total number of patients admitted to the female medical wards. The detailed results of this study are reported elsewhere. Diagnosis of some cases of cardiac failure was difficult. Idiopathic cardiomegaly was defined as cardiac failure without evidence of hypertension, or other recognisable cardiac disease, and, in women, without relationship to childbirth. Hypertensive heart-failure was defined as cardiac failure in which the blood-pressure was at least 150 mm Hg (systolic) and 100 mm Hg (diastolic) in two separate readings more than six hours apart. A few patients otherwise fulfilling the criteria for P.P.C.F. are included in this group. sons.

My thanks are due to Mr T. D. Lavery of the biochemistry laboratory, Royal Victoria Hospital, Belfast, who carried out the blood-alcohol tests, to Mrs J. Armstrong for help with the records, to the doctors and nurses of the accident and emergency department, who tolerated the work of a research project on top of a heavy burden of work, and to the Department of Health and Social Services, Northern Ireland, for a research grant. REFERENCES

1. Potter, J. M. Practical Management of Head Injuries. London, 1974. 2. Ellis, M. Casualty Officer’s Handbook. London, 1966. 3. Plewes, L. W. Accident Service. London, 1966. 4. London, P. S. Practical Guide to the Care of the Injured. Edinburgh, 1967. 5. Sproul, W. S., Mullaney, P. D. Emergency Care. St. Louis, 1974. 6. American

College of Surgeons, Early Care of the Injured

phia, 1972. 7. Rentoul, E., Smith,

H. Glaister’s Medical

Patient. Philadel-

Jurisprudence

and

Toxicology.

Edinburgh, 1973. 8. Simpson, K. Forensic Medicine. London, 1974. 9. British Medical Association, Drinking Driver. London, 1965. 10. Making, P. B. N. Z. med. J. 1971, 74, 278. 11. Rutherford, W. H., Merrett, J. D., McDonald, J. R. Lancet, 12. Champion, H. R., Caplan, Y. H., Baker, S. P., Long, W. Cowley, R. A., Fisher, R., Gill, W. ibid. 1975, i, 1402.

1977, i, 1. B., Benner, C.,

SEASONAL VARIATION OF CARDIAC FAILURE IN NORTHERN NIGERIA N. McD. DAVIDSON HELEN WATKINS

E. H. O. PARRY G. O. A. LADIPO

Department of Medicine, Ahmadu Bello University Hospital, Zaria, Nigeria The number of patients with cardiac failure admitted to hospital in Zaria, Nigeria, month by month during 1972-75 differed highly significantly between the cooler dry months and the hot wet months. The reasons are uncertain, but seasonal changes in blood-pressure and the effects of heat on the circulation and of humidity on the efficiency of be sweating may responsible.

Summary

Introduction PERI-PARTUM cardiac failure (P.P.c.F.) is the common cardiac disease in

northern

Zaria,

an

old

town

most

in the

guinea savanna of Nigeria., During our early investigations of p.p.c.F., we found that patients tended to appear in hospital more frequently during the hot sea-

Results

Peri-partum Cardiac Failure 1969-72 Admissions reached a peak in the middle of the year, just after the hottest season, but fell away quickly after August and- only began to rise again in the following February. These data have not been corrected for total female ward admissions because, during this study period, patients with P.P.C.F. were preferentially admitted and also because the number of patients who could be admitted to the female ward was strictly limited. These data are shown in fig. 2 (lower histogram). 1972-75 Cardiac Failure Study In this

three-year period,

cardiac failure in men, and

1024 TOTAL ADMISSIONS AND ADMISSIONS FOR CARDIAC FAILURE FOR MEN AND WOMEN CUMULATIVELY MONTH BY MONTH FOR THREt YEARS

JULY,

1972,

TO

JUNE, 1975

Figures for women are shown in brackets. in

related

unrelated to childbirth, was also more common in the middle months of the year. This variation, apparently independent of sex and of the total number of admissions, is shown in the accompanying table and fig 2. women

or

Statistical Analysis of Results The ratio of patients admitted with cardiac failure of all types to total admissions, month by month, is not constant throughout the year. A X2 test was used for goodness of fit (X2=55.22, d.f.=l1, P