Case note: Duty of Care and Material Increase in Risk

Duty of care: failure to consider sepsis in paediatric burns patient.

Mabior by her Next Friend Mary Kelei v Child and Adolescent Health Service

Reproduced article, originally published in Health Law Bulletin, Issue 26.4, a publication by LexisNexis Australia.

In the case of Mabior by her Next Friend Mary Kelei v Child and Adolescent Health Service (Mabior), Derrick DCJ of the District Court of Western Australia (the WADC) considered the question of liability of the defendant, for the failure of the doctors in its burns unit at Princess Margaret Hospital (PMH) to detect and treat a young burns patient for sepsis.

Background

At 5 pm on 9 December 2005, the plaintiff, aged 1 year and 4 months, was brought to Mirrabooka Medical Centre by her mother. She had suffered from water scald burns to her body, including partial thickness burns. Following examination by a doctor, the  plaintiff was transferred to PMH where she was admitted to the burns unit at 8.40 pm the same day. The plaintiff was assessed as having superficial and partial thickness burns to 18% of her total body surface area.

Throughout her time in the burns unit, the plaintiff demonstrated signs and symptoms, often present in a sterile inflammatory response or sepsis (separate conditions with similar indicators), both of which can lead to the development of Acute Respiratory Distress Syndrome (ARDS). However, the plaintiff tested positive for bacterial growth in her right knee and presented with a low neutrophil count — which are indicators more suggestive of sepsis.

Prior to her admission into PMH’s intensive care unit (ICU) the plaintiff was not treated with antibiotics. She went on to suffer hypoxic brain injury consequential to ARDS. The plaintiff alleged that the doctors responsible for treating the plaintiff in the burns unit breached the duty of care that they owed to her by failing to consider and treat for sepsis, accordingly, that their omission resulted in the ARDS and subsequent organ damage that ensued.

His Honour assessed whether the applicable standard of care is that of the hospital as a whole, or of an ordinary skilled practitioner in the relevant field of specialisation. Further, on the issue of causation, and in situations where the current state of medical knowledge does not explain the precise way in which the negligence of the defendant caused the plaintiff’s injury, his Honour was satisfied that an act or omission of the defendant which materially increases the risk of injury within the area of foreseeable risk may be relied upon to establish causation (in the context of s 5C of the Civil Liability Act 2002 (WA) (the CLA). Only the question of liability was considered by Derrick DCJ.

Issues considered

Derrick DCJ identified the following issues for determination:

  • Did the plaintiff develop sepsis?
  • What is the relevant standard of care?
  • Did the doctors breach the standard of care?
  • Did the breach cause the injury?

Did the plaintiff develop sepsis?

The defendant did not agree that the plaintiff suffered from sepsis. While the plaintiff showed clinical signs of sepsis, blood samples taken from her (and cultured) never confirmed the diagnosis. Derrick DCJ concluded on the balance of probabilities that the plaintiff did have sepsis on the evening of 10 December 2005, which evolved up until the time that she was transferred to the ICU late on 11 December 2005.

The medical experts appearing for the plaintiff put forward evidence that the constellation of symptoms (being tachycardia, tachypnoea, high temperature, neutropenia and raised inflammatory markers) furthered by the extreme magnitude of the respective symptoms for a paediatric burns patient, with burns to the extent that the plaintiff had suffered, were overwhelmingly likely the result of sepsis, as opposed to a sterile inflammatory response. The experts for the defendant submitted that a sterile inflammatory response was most likely the cause. Sepsis required treatment by antibiotics (which was eventually administered), whereas a sterile inflammatory response would not.

His Honour preferred the evidence of the intensivist and infectious disease experts for the plaintiff, giving particular weight to the evidence submitted by Dr Numa, an intensive care and paediatric respiratory physician and expert in ARDS and its causes, over the paediatric burns experts. His Honour reasoned that sepsis, the result of a bacterial infection, falls within the expertise of an infectious disease specialist; whereas ARDS, a respiratory disorder, is treated by intensive care physicians.

He based his decision on the following findings, among others:

  • Although Systemic Inflammatory Response Syndrome (SIRS) and ARDS can occur as a result of a sterile inflammatory response, the more common, if not most common, cause for both syndromes is sepsis.
  • The chance of a child of the plaintiff’s age, with such burns developing ARDS in the absence of sepsis is, if not “vanishingly small”, very low.
  • The plaintiff did have an Enterobacter infection of her right knee which was “more than a mere skin contaminant” and “was capable of contributing to or causing the infection”.
  • By the evening of 11 December 2005, the plaintiff presented with several features suggestive of sepsis rather than a sterile inflammatory response.
  • Although the symptoms are sometimes seen in patients suffering from SIRS in the absence of infection, the “severity and breadth” of the symptoms and the plaintiff’s “catastrophic and rapid decline” are more suggestive of sepsis.

Was the defendant negligent?

Standard of care

Derrick DCJ rejected the submission of the plaintiff that the proper standard is of an expert in paediatrics and that the standard of care should be “judged by reference to the standard of care of the hospital as a whole”. If the plaintiff’s view was accepted, the relevant standard of care would encompass the expertise of intensive care specialists and infectious disease experts, among other relevant specialties. His Honour regarded the concept of the duty of care of the hospital as a whole as “nebulous”, preferring the proposition that the conduct was attributable to the individual doctors who were responsible for the treatment of the plaintiff in the burns unit; therefore, that the standard should be constructed with reference to them. PMH was vicariously liable for the acts of its practitioners.

As a result, his Honour instead found that the proper standard of care is of an “ordinary skilled practitioner within the relevant field of specialisation” (being paediatric burns). However, his Honour qualified this by importing into the standard duty of a doctor of the relevant specialty to consult or seek the opinion from a doctor in a different specialty where the circumstances call for it.

Breach of duty

Widely accepted as proper professional practice

It was submitted by the defendant and accepted by Derrick DCJ that if it can be shown by the defendant that the doctors acted in accordance with a practice that is widely accepted as competent professional practice, then there can be no finding of breach of duty as per s 5PB of the CLA (widely accepted medical practice), unless it can be shown that the conduct was “in the circumstances of the particular case, so unreasonable that no reasonable health professional in the health professional’s position could have engaged in conduct in accordance with the practice.”

His Honour noted that the Western Australia Supreme Court of Appeal was yet to consider where the onus of proof lies under s 5PB, but that two decisions of the WADC had accepted that the onus of proving that the act or omission was not widely accepted as in accordance with competent professional practice lies with the plaintiff (the relevant standard being the balance of probabilities).

His Honour determined that the relevant question was not whether the plaintiff’s burns were treated in accordance with a widely-accepted practice, as submitted by the defendant, but rather, whether the failure to recognise that she was suffering or might be suffering from sepsis, the failure to test for signs of sepsis and commence antibiotic treatment was widely-accepted as competent professional practice. After consideration of the expert evidence, Derrick DCJ concluded that the answer to this question was “self-evidently ‘no'”.

Did the doctors breach the duty they owed to the plaintiff?

His Honour found that the failure of the doctors in the burns unit to recognise that the plaintiff may have been suffering from sepsis, and then to test for it and treat it, was a breach of the standard of care they owed to the plaintiff.

The expert evidence was mixed. However, the weight of opinion as assessed by Derrick DCJ established that although it is not recommended that antibiotics be used prophylactically in paediatric burns patients, they should be used where sepsis is either suspected or proven. His Honour reasoned that the appropriate course of action in the case of a paediatric burns patient where sepsis is suspected on clinical grounds is to take a sample of blood from the patient for culture and commence the administration of broad spectrum antibiotics as soon as possible — without waiting for the return of the results of a blood culture.

His Honour reached this conclusion, as the expert evidence suggested that the rapid decline that patients with sepsis often suffer in conjunction with the minimal risks that are faced as a consequence of administering antibiotics in cases where it turns out that there is no infection, weighs heavily in favour of treatment at an early stage before a diagnosis of sepsis is conclusive.

In relation to the facts of the case, his Honour judged that the plaintiff’s clinical symptoms warranted treatment with antibiotics by 2 am on 11 December 2005 at the latest. This was the time at which the results of the Full Blood Picture analysis on the blood sample taken at 10 pm on 10 December 2005 were available to the doctors. His Honour found that a reasonable person in the position of the burns unit doctors would have treated the plaintiff with antibiotics at the above time, in light of the “foreseeable and not insignificant risk” that the plaintiff did have evolving sepsis, as the disadvantages of administering the antibiotics in the case that it turned out that she did not have sepsis were “far outweighed” by the disadvantages of not administering antibiotics in the case that she did have sepsis.

Did the breach of duty cause the injuries?

Section 5C of the CLA deals with causation and s 5C(2) states:

In determining in an appropriate case, in accordance with established principles, whether a fault that cannot be established as a necessary condition of the occurrence of harm should be taken to establish factual causation, the court is to consider (amongst other relevant things) —

(a) whether and why responsibility for the harm should, or should not, be imposed on the tortfeasor; and
(b) whether and why the harm should be left to lie where it fell.

His Honour approved of the proposition, that the following principle is incorporated into the law of negligence under s 5C(2) of the CLA: That in cases of medical negligence, where it is impossible to determine whether the act or omission was a factor that materially contributed to the injury (in light of the state of medical knowledge at the time), if the act or omission materially increased the risk of injury to the plaintiff within the area of foreseeable risk, then a prima facie case is established that it led to the injury (material increase in risk). For this proposition, Derrick DCJ cited a range of authority, stating that Australian courts (including the High Court of Australia (the HCA)) have made statements in support of the principle, while falling short of adopting it.

Applying the “but for” test, which his Honour reiterated was adopted by use of the words “necessary condition” in s 5C of the CLA, his Honour concluded, based on the expert evidence that, it was more probable than not, that had the plaintiff been commenced on
antibiotics by around 3 am on 11 December 2005, she would not have developed ARDS to the extent that she did and the consequential injuries. Moreover, his Honour made a finding in the alternative that the plaintiff was otherwise successful on the point of causation, as the defendant failed to raise any evidence to rebut the pleading that the above described failures materially increased the risk of the plaintiff suffering injury.

Whether a material increase in risk can establish causation

Derrick DCJ considered that the incorporation of this concept was envisaged by the Review of the Law of Negligence: Final Report (the Ipp Report). The Ipp Report recommended that the principle be adopted in certain circumstances where it is appropriate to “bridge the evidentiary gap”, however warned that the difficult question of determining the appropriate circumstances to which the rule should be applied should be left to the common law.

In his judgment, Derrick DCJ noted that the HCA in Strong v Woolworths Ltd t/as Big W (Strong v Woolworths) proposed that, whether or not the concept of material increase in risk is imported into the common law, is yet to be decided. In its discussion of the New South Wales equivalent of s 5C of the CLA, the HCA in Strong v Woolworths justified its discussion with reference to the Ipp Report, which describes two types of cases (said to be exemplified by judgments given in the House of Lords), in which it may be appropriate to bridge the evidentiary gap. These are:

  • where there are cumulative causes and the extent to which each has contributed to the injury cannot be determined;
  • “material increase in risk” cases

Provisions similar to s 5C(2) of the CLA exist in New South Wales, Queensland, Tasmania and Victoria. Legislation in the Australian Capital Territory and South Australia makes it possible for the scope of liability to be extended in cases where it is “impossible to assign responsibility for causing the harm”, but only in circumstances where multiple persons have exposed the plaintiff to a “similar risk of harm”. The SA legislation refers to the United Kingdom case of Fairchild v Glenhaven Funeral Services Ltd by way of a note within the relevant provision. In that case, the House of Lords considered causation of mesothelioma in plaintiffs who were exposed to asbestos dust by more than one employer. The judgment is cited in the Ipp Report in relation to the concept of material increase in risk.

In the context of the Ipp Report and subsequent judgment of the HCA in Strong v Woolworths, courts of Australia (including superior courts) are generally supportive of the proposition that material increase in risk is adopted by s 5C of the CLA and its interstate equivalents. However, the proper scope of the provision, that is, the question of what constitutes an “appropriate case” for which departure from “factual causation” is justified, is yet to be elucidated by the HCA.

Conclusion

Mabior highlights the scope for causation to be taken as proved in difficult cases where the state of medical knowledge is not sufficient to clarify the relationship between the act or omission and the resulting injury. While there is strong judicial support for the application of the proposition that exposing the plaintiff to a material increase in risk within the area of foreseeable risk may be said to cause the plaintiff’s injuries, the point has not been finally determined. Greater clarity is needed as to whether this is a principle of law imported into the CLA, and its equivalent in other jurisdictions and if so, the scope of its application.

Reproduced article, originally published in Health Law Bulletin, Issue 26.4, a publication by LexisNexis Australia.

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