Wilsher v Essex Area Health Authority

Martin Wilsher was born on 14 December 1978. He was a tiny baby, and his birth was nearly three months early. His prospects of survival were very poor: according to one estimate they were as low as one chance in five. He could not breathe effectively, and for more than eleven weeks he needed extra oxygen. Repeatedly, the oxygen, carbon dioxide and acid balances of his blood went awry. From time to time he ceased to breathe. An early extra-ventricular haemorrhage led to hydrocephalus, for which he required surgery. On one occasion he was believed to have pneumonia. Undoubtedly, he lingered close to death, and there was always present the spectre of brain damage. Yet Martin is alive and well today with his intellect unimpaired. Beyond doubt this is due to the treatment which he received during his long days and nights in the special care baby unit at the Princess Alexandra Hospital, Harlow.

Sadly, Martin is nearly blind. He suffers from retrolental fibroplasia, an incurable condition of the retina. On his behalf it is said that this condition was caused by an excess of oxygen tension in his bloodstream during the early weeks, attributable to a want of proper skill and care in the management of his oxygen supply. A claim was put forward on his behalf against the Essex Area Health Authority, which is still before the courts, more than seven years after the event. After a trial which was made more difficult than it need have been by circumstances which I shall later describe, Peter Pain J. held the defendants liable in the sum of £116,199.14. Against that judgment the defendants now appeal.

This action, and the resulting appeal, give rise to three groups of questions:

1. Were there occasions during Martin's stay on the special baby care unit when the oxygen tension of his blood was allowed to attain and remain at an unacceptably high level? For this purpose, it is necessary to distinguish between a related series of incidents occurring in the first two days after the baby's birth, and a number of isolated occasions during the succeeding weeks. I will call these the "first episodes" and "later episodes" respectively.

2. Did any of the episodes of which complaint is made take place through any breach of duty for which the defendants are liable?

3. If so, was any breach of duty the proximate cause of the physical affliction, and the financial loss, of which the plaintiff now complains?

At the trial, there were other issues, relating to the aetiology of the plaintiff's current problems with his right eye, and to the proper quantification of his financial loss. The findings of the learned judge on these issues are not now disputed.

NARRATIVE

Before addressing the difficult issues of fact and law to which these questions give rise, it is convenient first to summarise the physiological and clinical background to the dispute, and then to set out in outline those aspects of the story which are not in dispute.

First, as to the bloodstream. Blood is the medium by which substances are carried from one part of the body to another. To each living cell are conveyed the materials which it needs in order to live and perform its own particular task: one of these materials is oxygen. The bloodstream also removes from the cells those waste products whose presence inhibits their functions: amongst these products is carbon dioxide. The blood is enabled to act as an efficient carrier of oxygen and carbon dioxide by the special properties of haemoglobin, the principal component of the red blood cell, which has the capacity to enter into reversible reaction with oxygen and carbon dioxide. The amount of these gases taken up by the haemoglobin is dependent on the partial pressure (or tension) of the gas in the blood. The reaction is rapidly reversible. Thus, the haemoglobin takes up oxygen under the high partial pressures encountered at the alveoli in the lungs and releases it rapidly when the partial pressure falls, at the tissues. Haemoglobin does not absorb oxygen indefinitely. There comes a point at which all the available haemoglobin has been converted to oxyhaemoglobin. This is reached at a partial pressure (PO ₂) of about 12 KiloPaschals (KPa). Beyond this point, a very small proportion of gas enters directly into solution in the blood fluids. As partial pressures are increased, the amount of oxygen thus transported by the blood is increased, but not in an efficient Banner, so that there is no point in increasing the PO ₂ indefinitely.

The transportation of carbon dioxide proceeds in a similar manner, but in the reverse direction. The partial pressure of carbon dioxide (PCO ₂) and the PO ₂ are related in a manner which it is unnecessary to describe. Another related variable is the pH value of the blood, a measure of the acidity or alkalinity of the fluid.

The blood is moved from one part of the body to another through the circulatory system. The motive agent is the heart. The right-hand portion of the heart is responsible for the circulation of venous blood. In the fully-formed human it receives into the right atrium the oxygen-depleted blood, via the inferior and superior vena cava. The blood passes to the right ventricle through a valve and is forced into the lungs via the pulmonary artery. Thence the oxygenated blood returns to the left atrium, enters the left ventricle and is pumped into the arterial system through the aorta and other vessels.

In the foetal child the mechanism is different. The baby depends entirely on the placental blood of the mother, which is already oxygenated. The infant lungs have no part to play. Accordingly, most of the blood flow across the lungs is short-circuited by two routes. First, the ductus arteriosus connects the pulmonary artery, which in the self-sufficient human conveys venous blood to the lungs, to the aorta which conveys arterial blood away from the heart. Second, a valve between the right and left atria, named the foramen ovale, admits blood from the right (venous) side of the heart to the left atrium, and thence to the left ventricle and the arterial side of the system. In the full-term infant, which can and must breathe through its own lungs, these short circuits are useless. The ductus arteriosus becomes vestigial, and the foramen ovale is soon tightly sealed.

The premature child is in a quite different situation. Mechanically and biochemically its system is not yet fully formed. It cannot breathe properly, or cannot breathe at all. Formerly, premature babies would die, or if they survived would suffer brain damage for want of sufficient oxygen. During the first half of this century medical science began to put this right. Premature babies were helped to breathe by artificial means, and were enabled to live in environments which were much richer in oxygen than ordinary atmospheric air. The result was a precipitous decline in the perinatal mortality of premature babies. Various methods are currently used to ameliorate the respiratory problems of premature babies. First, there is ventilation, called intermittent mandatory ventilation ("IMV") in the case papers, which employs electro-mechanical means to make the baby breathe. Second, there is continuous positive air pressure ("CPAP"), which maintains a pressure sufficient to prevent the lungs from entirely closing, and hence facilitates the opening of the lungs on the in-breath. Third, there is the provision of an oxygen enriched atmosphere, by a headbox or other devices, in which the baby can breathe spontaneously, with its respiratory deficiencies compensated by higher oxygen content of the air in the lungs. The records report the degree of enrichment in terms of percentages: sometimes the baby is breathing 100 per cent oxygen. The higher the percentage of oxygen when the baby is breathing, the higher the PO ₂ is likely to be, but the units in which the figures are expressed are different, and the two are only loosely connected.

The success of these developments in the neonatal care of premature babies has been dramatic. There are untold numbers of people alive today who would have perished, if born more than fifty years ago: or, if they had survived, would have suffered from irreversible brain damage. But after a while it began to seem that there might be a price to pay. In the early 1940's a quite new affliction was noticed. It was found that some premature babies were suffering from a formation of fibrous tissue behind the lens of the eye. For this novel complaint the term retrolental fibroplasia (hereafter "RLF") was coined. For a while, it was regarded simply as a disease of prematurity: i.e., as a disease to which premature babies were subject, but which had not previously been observed, because most premature babies died. In the 1950's, however, it was observed that there appeared to be an association, if not a correlation in strictly statistical terms, between the use of enriched oxygen to save premature babies from death or brain damage and the incidence of RLF. This led to a reaction, whereby...