Dear Editor

As well emphasized by Koppen et al,[1] congenital pulmonary arteriovenous malformation presenting in the neonatal period is an exceedingly rare anomaly, perhaps underdiagnosed. The index of suspition should be high if appropriate treatment is to be offered to these babies and, unfortunately, this was not the case in a 6-day-old patient seen by us 7 years ago.[2] Adding to the severe hypoxaemia, our case had isolated left ventricular overload demonstrated by the EKG and 2D-echo, which should have raised the strong possibility of a right to left shunt. Our index of suspition was moderate but not enough for the patient, despite attempted cardiac catheterization. This case should, in our view, be added to the other 12 mentioned by Koppen and so far reported in the literature. Also,this is perhaps the youngest patient reported and awareness of this possibility should be useful for the neonatologist.

Fernando Amaral
UNAERP Medical School

References

(1) S Koppen, CRW Korver, M Dalinghaus, CJJ Westermann. Neonatal pulmonary arteriovenous malformation in hereditary haemorrhagic telangiectasia. Arch Dis Child Fetal Neonatal 2002; 87:F226-F227.

(2) Amaral FTV, Félix PR, Granzotti JA, Rugolo LMS, Bernardes TA, Nunes MA. Fístula arteriovenosa pulmonar maciça. Causa rara, potencialmente curável de hipóxia neonatal. Arq Bras Cardiol 1995; 66:353- 355.

Dear Editor

Having recently reviewed the case notes of babies readmitted to hospital in the first 10 days of life (over a 1 year period), we firmly agree with the views expressed by Laing and Wong.[1] The incidence of documented hypernatraemic dehydration secondary to the failure of lactation in Bristol is 1.7 per 1000 live births much higher than that described by Oddie et al. [2] in the Northern Region (2.5 per 10,000 live births). In addition only 50% of infants readmitted with weight loss of <10% had a plasma sodium concentration measured. The true incidence of hypernatraemic dehydration secondary to lactation problems in Bristol could thus be as high 3.4 per 1000 live births. Our estimate could be an underestimate as our study looked only at infants readmitted within 10 days(Oddie et al looked at infants readmitted up to one month of age) and due to failure of recognition of this condition.

Laing and Wong [1] have proposed weighing all infants when the Guthrie blood samples are taken to identify those infants at risk of dehydration. We believe that this is too late as in many areas this occurs on days 7 or on day 10 with hand-over of care to the health visitor. We have already described a series of babies with hypernatraemic dehydration where all presented to hospital before day 7.[3]

The case has been made correctly [1, Newman] that newborn hypernatraemia is due to failure of successful feeding. While we agree that careful examination, observation of the infant while feeding etc may identify these babies we would dispute that this is currently universally possible. Due to midwifery shortages, postnatal wards are short staffed, community midwives are fully stretched and many women are discharged within a few hours of delivering. If a midwifery home visit does not coincide with a feed the mother’s assessment of feeding is assumed to be correct (as indeed it usually is). Weighing will reassure most mothers that their baby is following the normal pattern of loss followed by gain. Identification of excessive weight loss should prompt the health professional to examine the baby for evidence of illness and carefully observe breast-feeding technique. These mother-baby dyads could then be given additional support and advice in the community and thus successfully establish feeding. In our experience once the baby has become ill and required readmission to hospital the mother is reluctant to continue to attempt to breast-feed.

There continues to be confusion regarding the best way to manage this problem [1, Smith]. It should be remembered that these babies have normal guts and are suffering from starvation. If the infant is not shocked the rehydration can safely occur using enteral fluids – expressed breast milk or a breast milk substitute. Serum sodium should initially be measured six hourly and the volume of milk altered to ensure a slow return to normality.

We believe we need to foster a greater awareness of this problem and weigh the babies at risk around day 5 if we are to prevent tragedies from a common condition affecting otherwise well babies.

References

(1) Hypernatraemia in the first few days: is the incidence rising? Laing IA, Wong M. Arch Dis Child 2002;87:F158-161.

(2) Hypernatraemic dehydration and breast feeding: a population study. Oddie S, Richmond S, Coulthard M. Arch Dis Child 2001;85:318-20.

(3) Hypernatraemia: why bother weighing breast fed babies? Harding D, Cairns P, Gupta S, Cowan F. Arch Dis Child Fetal Neonatal Ed 2001; 85: F145.

Dear Editor

We are grateful to colleagues for their comments on our annotation.[1] We would stress that we merely abstracted the views of others so any criticisms (apart from our brevity) will be of the lawyers, doctors, nurses, physiotherapists and parents who contributed to the Royal Commission Report. We found it to be systematic, rational and objective.

We strongly refute any suggestion that any of the New Zealand professionals should be criticised let alone made scapegoats (witness our final paragraph). We are puzzled that Drs Rosenbloom and Ryan discount the quoted witness statements of the parents and involved clinicians. The lawyers and doctors are clear that the physiotherapy and nursing practices did occur and that the levels of head shaking were not monitored.

We are concerned with infant brain injuries not lung disease and consider this to be topical. We share colleagues’ concern at the need to base opinions on speculative presumption extrapolated from animal or accident research and are aware of the limited evidence that identifies the minimal forces needed to cause shaken brain damage in neonates or older infants. We found the reported experiences to be a helpful insight.

We are delighted that Dr Rushton (eLetter) has taken this opportunity to state he thought vigorous chest physiotherapy without supporting the head was responsible for the porencephalic lesions and to inform of his pivotal involvement in advising New Zealand colleagues. We understand there were earlier concerns that publishing the speculation about physiotherapy would open liability to litigation. Lawyers might consider the inference that fear of litigation led to suppression of information that might have prevented the New Zealand deaths and the dilemma facing clinicians who reported the cerebral implications of vigorous physiotherapy. Dr Knight reports (eLetter) their unit has been ‘subject to a long official public inquiry, law suits and had twenty medical, nursing and physiotherapy staff investigated by registration authorities, lasting 8 years.’

We do not accept criticisms of inaccurate references. The Cochrane review we both cited was last updated in 1997. There has been an updated review this year (dealing with lung not brain disease), which was unavailable to the editors or us at the time of submission. Dr Knight (eLetter) states there was no change in the vigour of chest physiotherapy from 1985 until the end of 1994 but he co-authored the paper [2] we cited that states that there was no policy to support the head during chest physiotherapy and no data on the extent the head moved during physiotherapy whether given by nurses or physiotherapists. The Royal Commission Report found no record of the vigour of chest percussion and understood there was considerable variation with no standardisation of training.

We recommend interested colleagues to read this Report and the publications of Knight and Harding et al before dismissing the possibility that vigorous chest physiotherapy without supporting the head may cause brain injuries in certain circumstances.

References

(1) Williams AN, Sunderland R, Neonatal shaken baby syndrome: an aetiological view from Down Under. Arch Dis Child 2002;87:F29-30

(2) Knight DB, Bevan CJ, Harding JE, et al. Chest physiotherapy and porencephalic lesions in very preterm infants. J Paediatr Child Health 2001;37:554–8.

Dear Editor

I am grateful to Laing and Wong for raising once again the issue of hypernatraemic dehydration in the first few days of life.[1] However, I think it is important to remember that hypernatraemic dehydration, like anaemia, is a sign of disease not a diagnosis in itself. A low haemoglobin concentration in blood can be caused by a large number of different pathological and physiological processes. Hypernatraemic dehydration should be seen in the same light.

Laing and Wong’s article describes two situations in which a child can be found to exhibit the typical biochemical and clinical features of hypernatraemic dehydration, i.e. weight loss and hypernatraemia. The first mentioned is associated with gastroenteritis in a bottle fed infant, commonly a few weeks old and the second is seen in ‘breastfed’ infants in the first few days of life. The hypernatraemia associated with these situations is caused by different problems with water balance – in neither is the problem an increased intake of sodium. In the infant with diarrhoea there is an excess loss of water and in the ‘breastfed’ baby an insufficient intake of water.

In discussing hypernatraemic dehydration in association with diarrhoea in young infants Laing and Wong refer to a paper by Chambers and and Steel [2] where attention is drawn to the slightly increased concentration of sodium in artificial milk mixed incorrectly by parents. This is a red herring. The excess sodium concentration of the artificial milk mixed incorrectly by the mothers reached a maximum of 59 mmol/L with a mean of 37.2 mol/L. Those who believe that this concentration of sodium could be responsible for hypernatraemic dehydration should remember that the concentration of sodium in the standard oral rehydration solutions in use in this country is 60 mmol/L (Dioralyte®, Dioralyte Relief®, Rehidrat®), or in one case 50 mmol/L (Electrolade®) and that the WHO formulation for oral rehydration solution contains 90 mmol/L of sodium.

In fact the cause of this association of hypernatraemic dehydration with diarrhoea is the continued feeding with artificial milk after the onset of diarrhoea. The intestinal hurry associated with gastroenteritis results in the delivery of a solution rich in protein and complex carbohydrates to the colon which, after digestion by colonic bacteria, produces a considerable osmotic load in the colon which in turn results in the production of voluminous stool low in sodium.[3] The result is hypernatraemic dehydration due to excessive water loss. Those who require further discussion of this hypothesis are advised to read the excellent paper by Hirschhorn.[3]

The second situation relates to the title of the piece namely, hypernatraemic dehydration in the first few days of life in association with ‘breastfeeding’. Though the breast milk produced, in very small quantities, by the mothers of these children is often found to contain a high concentration of sodium, this has nothing to do with their hypernatraemic state. As Jack Newman so eloquently puts it in his electronic response to Laing and Wong, these babies are not dehydrated because they are breastfed but because they are only pretending to breastfeed. They are, in fact, starving. This is amply illustrated by the case described in Oddie et al of a ‘bottle fed’ baby admitted at six days of age with hypernatraemic dehydration whose dehydration had nothing to do with the bottle milk being ‘fed’ to her but was caused by the fact that she had oesophageal atresia. Hypernatraemic dehydration is frequently seen in the elderly and the mentally handicapped when their need for basic care, and presumably a regular intake of water, is neglected. [5,6,7]

Hypernatraemic dehydration is a sign of illness not a diagnosis. It is commonly caused by excess water loss or by insufficient water intake either alone or in combination. It is almost never the result of excess sodium intake which would result in retention of water and an increase in body weight, though this would obviously require intact thirst mechanisms and access to sufficient water.

Sam Richmond

References

(1) Laing IA, Wong CM, Hypernatraemia in the first few days: is the incidence rising? Arch Dis Child Fetal Neonatal Ed 2002; 87: F158-F162.

(2) Chambers TL, Steel AE. Concentrated milk feeds and their relation to hypernatraemic dehydration in infants. Arch Dis Child 1975; 50: 610-5.

(3) Hirschhorn N. The treatment of acute diarrhea in children. An historical and physiological perspective. Amer J Clin Nutrition 1980; 33: 637-63.

(4) Oddie S, Richmond S, Coulthard M. Hypernatraemic dehydration and breastfeeding: a population study. Arch Dis Child 2001; 85: 318-20.

(5) Aaronson L, Seaman LP. Managing hypernatremia in fluid deficient elderly. J Gerontol Nurs 1989; 15: 29-34

(6) Miller PD, Krebs RA, Neal BJ. McIntyre DO. Hypodipsia in geriatric patients. Am J Med 1982; 73: 354-6.

(7) Himmelstein DU, Jones AA, Woolhandler S. Hypernatremic dehydration in nursing home patients: an indicator of neglect. J Am Geriatr Soc 1983;31: 466-71.