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10. Critical care

The following guidance has been provided by the Intensive Care Society.

10.1 Building capacity

Existing guidance on expanding critical care capacity ⁴⁵ recommends a target of a 100% increase from normal bed availability, though it is clear that this is still unlikely to be sufficient to meet all demand. This is recognised by the guidance:

'In planning for this expansion of capacity, it must be recognised that only a basic or limited level of critical care may be possible. Local circumstances, including access to additional ventilators and the layout and proximity of facilities - such as the size of the normal elective workload or the location and size of facilities such as post recovery areas - will mean that some services may not be able to identify as much potential additional capacity as others.

'Modeling has been undertaken to examine the impact of a variety of scenarios involving pandemic influenza. It is clear that in the worst case scenarios services, including critical care, will not be able to provide the usual standards of care. Therefore, in seeking to identify additional capacity, NHS critical care services should take into account that it is assumed that all but the most urgent scheduled care will have been suspended and that it is anticipated that care in additional capacity will be at a basic level only with levels of staffing appropriate to an emergency. In these circumstances it is understood that ways of working and clinical practices may have to be adapted but should be sustainable for a period of up to three months.

To support this guidance, ' Phased Responses' has been developed by the Intensive Care Society with contributions from the expert working group and is helpful advice that can be applied during an emergency including pandemic influenza. ' Phased Responses' provides a framework for considering the implementation of phased response patterns and triage for the care of critically ill patients in the event of an emergency. ⁴⁶

The Intensive Care Society document on ' Phased Responses' (extract in appendix 13) has been published in the Journal of the Intensive Care Society. ⁴⁷

10.2 Admission and discharge criteria in the critical care setting

Despite such expansion plans, the potential number of referrals to critical care is likely to exceed bed availability. Calculations based on the National framework⁴⁸ suggest that even if existing critical care bed capacity can be maximally escalated, during the peak of a pandemic there may be ten times as many patients requiring mechanical ventilatory support as the number of beds available.

In such context, the principles that must apply are that:

• critical care is preferentially provided for individuals who are most likely to benefit, so as to minimise the number of avoidable deaths ⁴⁹
• people with an equal chance of benefiting from critical care should have an equal chance of receiving it
• triage/treatment decisions are made on a rational, non-arbitrary basis, supported by objective evidence.

There is an emerging literature from Canada and the USA around prioritisation and triage in a pandemic; ⁵⁰ Christian et al. ⁵¹ have proposed a protocol for triaging patient access to critical care during a pandemic. It consists of inclusion criteria, exclusion criteria, minimum qualifications for survival and a prioritisation tool that can be modified according to resource availability. The exclusion criteria consist of three categories of patients: those who have a poor prognosis even if cared for in an intensive care unit; those who require resources that will not be available during a pandemic; and those with advanced illness whose underlying illness means that they have a high likelihood of death even without their current, concomitant critical illness ( appendix 11). The inclusion/exclusion criteria for intensive care may have to be applied in the primary care setting to avoid admitting inappropriate patients to hospital.

Christian et al. also considered a number of different severity scoring systems for use in the assessment process, and opted for the Sequential Organ Failure Assessment ( SOFA), given its physiological basis, its ease of use and its validation in the critical care setting (a table showing the components of the system is given in appendix 14).

During a pandemic, if the usual standard of care were to be applied in intensive care, then it could be days or even weeks before the inevitability of a poor outcome was accepted, by which time several patients who might have benefited from treatment would have been denied treatment. During a pandemic, when staffed critical care and acute beds are scarce, it will be important to identify at an early stage those patients not responding to treatment and therefore likely to have a poor outcome. It is proposed that, once treatment and care start, in addition to any routine monitoring and assessment each patient should have regular, formal periodic assessments to determine whether:

• they are responding to treatment and either are fit enough to be discharged or still need further treatment
• they are not responding to treatment or are deteriorating despite treatment, and so further treatment should be withheld in favour of symptom relief.

SOFA scores can be used to assist in this process. High SOFA scores indicate a greater number of organs failing, the extent to which the organ is failing and therefore the higher probability of death. A SOFA score greater than 11 is associated with only a 10% chance of survival. A SOFA score of 11 or higher may be considered to represent 'a ceiling on the amount of resources that can be expended on any one patient. ⁵² In addition to the usual assessments, formal assessments using SOFA should be made on admission, at 48 hours and then again at 12-hourly periods, with the SOFA score being used to determine further action (Table 9). Full details of the process are described in the paper by Christian et al.

Table 9: Example of 48-hour assessment in critical care ^*

In addition to the use of SOFA, experienced clinicians should continue to work towards identifying other criteria or conditions which may assist in prediction of patients who have not been excluded by SOFA scale assessment but are unlikely to have sustained benefit from mechanical ventilation.

Clinicians should be alert to the possibility of emerging outcome/predictive clinical indicators which may become available from information accumulated during the evolution of a pandemic.

For patients in whom mechanical ventilatory support has already been initiated, it is recommended that subsequent decisions (including treatment withdrawal) can be based on the SOFA triaging system. This is controversial and will add additional challenges to the responsibilities of critical care teams. The problem with this approach in the context of a range of aspects of care, including mechanical ventilation in intensive care, is that withdrawal of the care can be reasonably predicted to result in death. This creates difficulties which are distinct from the normally accepted ethical position in this context whereby there is no ethical difference between withholding and withdrawal of aspects of intensive care when these decisions are being made on the basis of futility. Where such decisions are made on the basis of triage or prioritisation, significant divergence may emerge between withholding and withdrawing care. These may be on ethical, moral and/or legal grounds and require further exploration before this course of action can be absolutely recommended.

For patients with a low probability of survival, or for whom the predicted duration of critical care is likely to be such that many others will be consequently denied access to critical care, agreements will need to be reached on limits of treatment escalation and the point at which the priority of care changes to maintenance of comfort and dignity.

The necessity to triage critical care admissions using criteria that will differ from those used in routine clinical practice, will cause controversial ethical issues and the prospect of litigation (in 'real time' or retrospectively) directed against clinicians responsible for these decisions. In order to help maintain staff morale and prevent the potential of inappropriate professional criticism or litigation, triaging decisions should be shared by at least two experienced consultants, and should be in accordance with explicit local policies based on national standards agreed with high level local and regional management. Full documentation of the decision-making process should also be recorded.

Such agreements do not remove the responsibilities of staff to prioritise patient safety, but should ensure that they will not be vulnerable for doing the best that can be done under difficult circumstances.

Additional security measures may be necessary because of the risks of violence directed at staff making triage decisions.

The required strictness of triaging decisions will vary according to the scale of the problem and its geographical extent. The necessity for triaging patients will also be influenced if additional critical care capacity exists elsewhere and if transport logistics allow these to be accessed. Accordingly, a staged triaging structure should be created, with the progression criteria being agreed by local consultation. A staged approach to triaging is outlined in appendix 13.

Ranking according to benefit (including considering the benefit of ICU treatment, the harm of missing out and the potential to mitigate the harm should the patient miss out) will determine access for many patients. However, in the face of high demand there may be patients between whom the clinicians cannot differentiate on the basis of benefit. At this stage allocation of ICU treatment may require to be by a random selection (lottery) process taking into account the principles of the ethical framework ( appendix 2).

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