COLPOSCOPY

690 of the population must concentrate on altering the taste for salt of that population--otherwise, people will add salt at home to foods processed without salt. James and colleagues imply that dietary salt restriction is an established means of limiting the usual rise in blood pressure with age, and thus the development of coronary artery and cerebrovascular disease. However, in the references they cite, not one provides any evidence that dietary salt restriction actually limits the genesis of hypertension in normotensive subjects; indeed, the majority are reviews and some are reviews of reviews. Only one paper reports the effects of a controlled trial of sodium restriction in essential hypertension. To point out as justification for dietary salt restriction that current intake in affluent communities exceeds the physiological requirement is nonsense. Do they propose limiting the intake of other minerals or vitamins to the physiological requirement (where known), or indeed would they limit water, protein, carbohydrate, and fat-all consumed in excess of requirement? Our diet has evolved on the principle of excess consumption of all essential nutrients. What we need is used or stored, and any left is eliminated. If we are serious about controlling hypertension, then what is needed is wider use of the sphygmomanometer and not another diet sheet. 20 Wimpole Street, London W1M 7AD

ALEXANDER L. MACNAIR

COMMUNITY CAMPAIGN FOR IRON DEFICIENCY

SIR,-Your editorial (Jan 17, p 141) draws attention to the relation between iron deficiency and psychomotor development in children. There is much evidence for an association between iron deficiency and delayed or impaired development.l However, the differences between iron-deficient and iron-replete children, though statistically significant, are small and within the normal range. It should not be assumed that children with iron deficiency are suffering from a major impairment of intellectual development. Furthermore, similar changes have been shown in adolescents2 and adults.3 If iron deficiency needs investigation and treatment, our efforts should not be directed solely towards toddlers. Royal Manchester Children’s Hospital, Pendlebury, Manchester M27 1HA

D. I. K. EVANS

1. Evans DIK. Cerebral function in iron deficiency: A review. Child Care Health Dev 1985; 11: 105-12. 2. Webb TE, Oski FA. J Special Ed 1974; 8: 153-56. 3. Tucker DM, Sandstead HH, Penland JG, Dawson SL, Milne DB. Iron status and brain function: Serum ferritin levels associated with asymmetries of cortical electrophysiology and cognitive performance. Am J Clin Nutrition 1984; 39: 105-13.

EARLY-ONSET AND LATE-ONSET PNEUMONIAS IN INTENSIVE CARE UNITS

SIR,-We have a different interpretation for the data of Dr Mandelli and colleagues (Nov 8, p 1094) and we also have new data on the pathogenic mechanisms of nosocomial pneumonias in intensive care units (ICU). Mandelli and colleagues suggest that patients with early-onset pneumonia (EOP) constitute a specific subgroup of patients in an ICU whose pneumonia may differ in pathogenesis, prevention, and treatment from those with later-onset pneumonia (LOP). The evidence included the consistent proportion (about 55%) of EOP in all pneumonias in ICUs from 1978 to 1984, and an unchanged case-fatality rate of about 35% during this period. However, we think that most cases of EOP (clinically present before the fourth day in an ICU) are acquired in hospital wards before entry to the ICU where the clinical debut occurs. The reason that the stay in the ICU of EOP cases is usually shorter than the expected incubation period for pneumonia. Despite a different place of infection EOP and LOP may share the same pathogenic mechanisms of aspiration of bacillicontaminated pharyngeal secretions in debilitated patients. The frequency of EOP has decreased in the same proportion as all pneumonias have decreased from 1978 to 1984 (see table in original letter). This consistency is explained if the prevention measures that

PHARYNGEAL COLONISATION AND PNEUMONIA INCIDENCE IN UNTREATED PATIENTS AND IN PATIENTS TREATED WITH ORAL WASHINGS WITH CLORHEXIDINE

I

I

instituted in ICUs from 1978 act on the same risk factors or pathogenic mechanisms for both groups of pneumonias. We have retrospectively studied 1034 consecutive patients admitted to a surgical-medical-respiratory ICU between January, 1984, and April, 1985. More than half the pneumonias occurred before the sixth day in the ICU. The mean time to the occurrence of pneumonia was 7 days (SD 5), However, except for those whose pneumonia was clinically evident the first day in the ICU, pharyngeal colonisation preceded pneumonia, both EOP and LOP. This temporal relation suggests a role for colonisation in the induction of pneumonia, but the relationship occurred in both groups of pneumonias. From November, 1984, to April, 1985, we treated all patients admitted to the ICU with oral washings with chlorhexidine (5 % in saline solution), three times daily. We checked for a similar distribution of the main risk factors for pneumonia in the two groups before and after this period.2 Chlorhexidine washings produced a similar decrease (33% and 29%) in the incidence of pharyngeal colonisation and pneumonia (table), which suggests that, when colonisation is prevented, pneumonia incidence is reduced. We do not claim that chlorhexidine oral washing is effective for pneumonia control in an ICU because there was no overall improvement in case-fatality in our ICU and the results

were

obtained in a randomised trial. However, the effect of chlorhexidine in decreasing colonisation and pneumonia was the same in EOP and LOP, which suggests that pharyngeal colonisation is a common pathogenic mechanism for both groups of

were not

pneumonia. Why has the case-fatality rate of EOP not decreased between 1978 and 1984 (according to Mandelli and colleagues)? A plausible reason is that EOP usually occurs in patients with serious underlying diseases. In these patients, mortality is strongly influenced by the underlying disease and only slightly influenced by the occurrence of pneumonia. Thus recent therapeutic advances, especially those for the treatment of pneumonia, have not increased survival. Department of Preventive Medicine and Intensive Care Unit, Hospital "La Paz", P- de la Castellana 261, 28046 Madrid, Spain

FERNANDO RODRÍGUEZ ARTALEJO JUAN GARCÍA CABALLERO ANTONIO AGUADO MATORRAS JUAN DEL REY CALERO

Artalejo FR. Epidemiologia de las neumonias de las UCIs: Factores de riesgo y prevención. Madrid: Universidad Autónoma de Madrid, 1986. Thesis. 2. La Force FM. Hospital acquired pneumonia: Epidemiologic summary and clinical approach. In: Pennington JE, ed. Respiratory infections: diagnostic and 1.

management. New York: Raven Press, 1983: 135-42.

COLPOSCOPY

SIR,-Further to your editorial on colposcopy (Feb 28, p 486) I follow-up of previously treated cervical intra-epithelial neoplasia should routinely include cervical curettage. After lasertherapy, cryotherapy, and cone-treatment, the transformation zone/squamocolumnar junction will be inverted, and not accessible by colposcopy. Cytological tests alone can be unreliable. The benefit of colposcopy in cytologically detected dysplasias cannot be stressed enough. Directed biopsies of minor lesions will prevent an increasing number of mutilating surgical interventions.

feel that

Dyewadsgate 2, Majorstuen, 0367 Oslo 3, Norway

PEER HOEVIK