Select Committee on Science and Technology Minutes of Evidence


Memorandum by the Intensive Care Society

THE PROBLEM

  1.  A recent paper from the Intensive Care Society1 used a model provided by the US Center for Disease Control and Prevention (CDC)2 to estimate the impact of an influenza pandemic on critical care services in England.

  2.  Using plausible inputs for this model (a 25 per cent attack rate and 8 week pandemic duration) we estimated bed occupancy for Level 3 critical care beds that exceeded 200 per cent from the pandemic alone. This scenario does not account for prevailing high occupancy rates in UK ICUs in the absence of a pandemic (typically 85-90 per cent).

  3.  Current ICU resources would be overwhelmed if the assumed 15 per cent ICU admission rate and 7.5 per cent ventilation rate for hospitalised patients were to materialise. These are not outlandish figures - there is a clear problem

  4.  However, the exact magnitude of this problem is difficult to estimate, given the paucity of data for ICU admission rates with influenza. Some data are available for the surrogate of community-acquired pneumonia,3-7 but there are wide variations in both ICU admission rates (3-20 per cent of hospitalised patients) and mechanical ventilation (37-88 per cent of ICU admissions). The available evidence suggests that inter-institutional variations in provision of ventilatory support are less than those for ICU admission.5 Since the need for artificial ventilation is a hard outcome in terms of health economics and resource requirement, this may be a better end point to focus on.

  5.  Best North American estimates for community acquired pneumonia suggest ICU admission rates of ®10 per cent overall, with about half of these requiring ventilatory support.5

  6.  However, these figures need to be viewed with some caution in the light of the high incidence of primary viral pneumonia and reported mortality of >50 per cent for recent human cases of H5N1infection in the Far East.8 The current strain of the virus would seem to be extremely virulent, suggesting a higher rate of admission to intensive care and need for mechanical ventilation. In addition, the need for ICU facilities may be significantly modified by the propensity of the virus to cause exaggerated cytokine responses. Indeed, in past episodes, the morbidity and mortality have been related to these aspects of viral pathogeneicity.10

  7.  In the event of human-to-human transmission with a virus of this virulence and high infectivity, intensive care colleagues in Hong Kong (population 7 million) are bracing themselves for 2 million infected subjects with a 10 per cent ICU requirement (200,000 patients). Many hospitals in Hong Kong have expanded ICU isolation facilities. When the Hong Kong Infectious Diseases Centre is finished next year it will have 12 purpose built ICU Isolation Rooms with negative pressure ventilation (Buckley T, Personal Communication). The whole centre, which consists of 108 beds, will have negative pressure ventilation. The total number of ICU beds with negative ventilation in Hong Kong is reported to be in the hundreds (this is not fully substantiated).

  8.  It has been reported that no patient who has been infected by the avian H5N1 strain in Vietnam, and has required ventilatory support, has survived. There may be questions regarding the promptness and quality of critical care delivered to these patients. However, if these issues are clarified and the report is confirmed, then we need to think carefully about when and where we deploy scarce critical care resources. Indeed, informal reports from the Far East and Australia suggest that they have at least considered conceding that it would be impossible to provide conventional intensive care in this context. At the very least, we may need to develop robust triage systems.

  9.  Unlike ICUs in Australasia and Canada (which experienced the SARS outbreak), UK intensive care units have little experience of dealing with, or even preparing for, an infectious disease outbreak of this magnitude. There needs to be close attention paid to infection control education and enforcement - including and up to the designation of enforcement officers who ensure that precautions are adhered to.

  10.  The availability of staff for ICU expansion, or even running current levels of capacity, may be severely compromised by staff sickness (25 per cent) and fear of coming to work. Indeed, a recent publication suggests that less than 50 per cent of nursing staff would be able to or willing to report for work in such circumstances,9 because of staff sickness, sickness in family members, or the fear of acquiring and transmitting the disease. It is important to recognise this latter factor, and make attempts to assure the safety of staff, as far as is possible, by providing protective equipment, antivirals, and the best immunisation available at the time. It may be important to find hospital based accommodation for key staff who are exposed to high risk of infection, so that they can minimise the risk of taking infection home to their families.

  11.  These problems of inadequate critical care would be worsened by variable resource availability, which may be appropriate for current casemix, but not necessarily for pandemic geography.

  12.  We also need to consider the impact of disease specific epidemiology - clustering in urban areas or near regions where disease entry into the country is likely.

POTENTIAL RESPONSES

  1.  The ICU community needs to be involved in contingency planning (the ICS has specific individuals with responsibilities for these issues).

  2.  We need better modelling with hard UK data to address the magnitude of the problem and the extent of available solutions. Dr Menon and the ICS have begun to address modelling with UK data as part of a dialogue with the DoH (collaboration with Daniel Wood and Peter Grove, with potential involvement of David Harrison of the Intensive Care National Audit and Research Centre (ICNARC).

  3.  There are potential means of expanding ICU capacity temporarily, which have been explored in published contingency plans.11 In the UK setting, this may be initially achieved by converting Level 2 to Level 3 beds, and creating temporary critical care resource in operating theatres and recovery areas.

  4.  Individuals who work in these areas (recovery nurses and operating department assistants) have the requisite clinical and technical skills to support critical care staff. It is essential that we accelerate rotation of non-ICU staff through ICU areas to build up a larger cohort of staff that could be called on to help in the context of a pandemic.

  5.  There is likely to be a fine balance between useful ICU expansion (with preserved basic care standards) and over-expansion (to an extent that the care systems, clinical skills, and discipline inherent in critical care are lost). There is no point in admitting patients to expanded ­intensive care areas" if they do not get a higher standard of care. Discussions with colleagues in Hong Kong with experience of the SARS epidemic suggest that a 50 per cent expansion may be tolerated, but this will vary from hospital to hospital.

  6.  We should consider, on a hospital-by-hospital basis, the development of critical care services in isolation/infectious disease wards. If this is thought appropriate we need to organise the services that will be required in these areas - piped oxygen, suction and air, and protected power supply.

  7.  Non-NHS (eg private sector) critical care resources should be logged and quantified. The NHS should develop agreements that will allow us to use these resources in the event of a pandemic. Consideration should be given to using these facilities, where adequate and appropriate, as centres for ­clean" (ie non pandemic related) essential clinical activity.

  8.  We need to have clear central triggers to move from standard to crisis mode - ideally as a staged escalation. This will avoid any confusion about when current priorities (eg waiting lists etc.) can be set aside to deal with the pandemic.

  9.  We need to create and maintain libraries of critical care equipment in hospitals. Equipment shortages may also be addressed (at least partly) by dialogue with industry and imaginative resource expansion schemes. For example, it may be possible to induce vendors of clinical monitoring, ventilation, and infusion devices to increase their stock levels. This would provide equipment that was available for rapid deployment. Increases in stock levels may require the payment of a relatively small retainer.

  10.  Such ICU expansion is not compatible with continuing adherence to conventional clinical standards and targets - public education is essential to manage expectations.

  11.  There need to be clear plans at a hospital level, including rapid access to protective equipment for staff (perhaps chemoprophylaxis for carefully defined subgroups of key hospital workers). We also need to stockpile antibiotics (especially antistaphylococcal antibiotics) for the treatment of secondary infections.

  12.  Regardless of preparations, resources may be overwhelmed in many hospitals, and we need to consider two options (both may be required, and should certainly be explored):

    a.  transfers will occur, and we need to make provision for this;

    b.  we may need to bring skilled staff to hotspots, rather than transfer patients.

  13.  We need to make plans for the recovery and aftermath - catching up with waiting lists etc.

  14.  It may be prudent to consider whether current indemnities will provide adequate cover, both in terms of individual life insurance (if clinical staff voluntarily go into areas with high infection risk) or organisational responsibility (where the NHS utilises staff working at the margins of their clinical competence).

POTENTIAL OPPORTUNITIES

  While an influenza pandemic may be clinically devastating, it may also offer unique research opportunities. There is a strong argument for identifying research funding, developing research protocols, and applying for regulatory authorisation to conduct such studies now, so that we are prepared if and when a pandemic strikes. This process needs to be urgently undertaken, and should involve (but not be limited to) epidemiologists, public health physicians, virologists, immunologists, general physicians and intensivists.

  We should plan to get regulatory approval from MREC that covers issues relating to the Mental Capacity Act (the sickest patients will be unable to provide consent), EU Clinical Trials Directive (to assess antiviral drug and vaccine efficacy and safety), the Human Tissue Act (research will almost inevitably involve blood samples), and the Data Protection Act (to allow clinical data collection and processing). I would suggest the following actions:

    [a]  We define a minimum clinical dataset from all patients that would be used for epidemiological analysis, and could provide data for use across many studies. This would be best designed as a series of nested data collection instruments, with increasing complexity of data collection as the severity of disease increased. NHS Direct are keen to provide the base for this, and I would see them collecting basic data on demographics, comorbidities and symptomatology. A proportion of patients would present to GPs, either directly or via referral by NHS Direct, and could have additional data collected on these topics, as well as information about vaccination and antiviral drug use. A smaller number would present to hospital, where detailed clinical and laboratory data could be collected. Finally, we expect a small proportion of hospitalised patients to come into ICUs, where additional data will be available. It is essential that we have good quality outcome data for the hospital and ICU segments of the populations, including length of hospital stay, treatment and mortality.

    [b]  It would be ideal if we could achieve such data collections within the framework of existing administrative datasets. As far as the ICU segment was concerned, the perfect framework would be the ICNARC Casemix Program, which provides high quality audit for the vast majority of ICUs in England and Wales (including data on disease severity and organ failure quantitation and 28 day mortality). The additional resource required to obtain data of specific relevance to the pandemic have not been quantified, but are likely to be small. We should explore the use and expansion of similar administrative datasets in less acute settings.

    [c]  We should identify a matrix of GP surgeries, hospitals and critical care units wishing to participate as stakeholders in a research collaboration that pursued a range of pre-specified studies. A collaboration covering 2 million individuals (®2 SHAs), would result in an estimated 100,000 GP consultations, 3,000 hospitalisations, 1000 ICU admissions, and 2,000 deaths (based on HPA estimates).

    [c]  In the subset of the NHS identified in [b] above, patients could be involved in more detailed studies. In these patients we should bank a sample of blood for DNA extraction, and store acute and convalescent blood samples to assess host responses, including the development of immunity. Possible synergies with the UK Biobank initiative that should be explored.

  Two potential research areas are described below as examples. I have listed studies at two ends of the research spectrum to provide a view of the range of opportunities available:

  1.  Clinical trials of antiviral therapy and vaccination in the early phases of the epidemic

    When the pandemic first strikes we will be using neuraminidase inhibitors and/or novel vaccines with an extremely small (or possibly nonexistent) evidence base. Rapid processing of results from early in the epidemic may allow more optimal use of a range of therapeutic options in subsequent pandemic waves, or even later in the course of the first wave of the pandemic (especially if it is prolonged). Similar considerations apply to the use of protective measures. Assessing the efficacy of barrier protection and antiviral chemoprophylaxis in hospital staff at high risk of infection might provide important early pointers for the use of these interventions in the general population. We need to identify the key interventions that we wish to evaluate now, but provide enough flexibility in funding and study organisation to respond to unexpected challenges and opportunities.

2.  Genotype and outcome from major illness    There has been much interest in how genetic regulation of the innate immune response affects survival from critical illness. At one extreme, an inadequate proinflammatory cytokine response may result in high mortality from infection. At the other extreme, an excessive proinflammatory host response may, in itself, predispose to multiple organ failure and death.

      The ability to define critical components and optimal levels of the immune response that enable survival could allow risk stratification and selection of patients for intensive monitoring and specific anti-inflammatory therapy. However, clear understanding in this area has been limited by small patient numbers in most studies, and by the heterogeneity of critical illness (in terms of aetiology, disease severity, therapy, and host variability).

      An influenza pandemic presents a unique opportunity to address these questions in situations where a large number of individuals (potentially up to 25 per cent of the UK population) have a stereotyped biological insult, have similar therapy, and clear outcome measure (mortality). The data that result from a genetic study which involved only a fraction of individuals in this setting would be immensely valuable, not only in the context of influenza, but also for other infections and for non-infectious critical illness.

ACTION POINTS:

  1.  Complete the ICS/ICNARC/DH calculation of ICU admission rates for seasonal flu like illness.

  2.  Individual hospitals to run Flusurge 2.0 for their practice, with a range of inputs decided after the ICS/ICNARC/DH simulation exercise.

  3.  The DH should talk to the independent sector nationally, and encourage individual hospitals to do the same on a local basis. It is important to identify the ICU facilities that are available in these hospitals, and agree on ways in which these can be used in the event of a pandemic.

  4.  The DH should talk to medical equipment manufacturers and define current stock levels. We should also explore ways of rapidly making additional equipment available (eg by increasing stock levels).

  5.  Published infection control measures need to be cascaded down to ICUs, and their preparedness audited (both in terms of knowledge and availability of equipment).

  6.  Critical Care Medical and Nursing leaders to identify areas in which non-ICU staff can provide useful support - can be within the auspices of the Critical care Contingency Planning Group. Similarly, the Intensive Care Society should identify core medical skills that will allow expansion of ICU medical staff.

  7.  Hospitals should undertake evaluation of the ability to expand or upgrade the physical space available for critical care. This may require a specific simulation exercise which should be funded. Such expansion will include conversion of Level 2 to Level 3 facilities, and utilisation of operating theatres and recovery areas. Where geography is favourable, individual hospitals may consider expanding infrastructure for critical care (medical gases, suction and protected power supply) to infectious disease wards.

  8.  Initiate hospital based cataloguing of spare ventilatory and monitoring equipment. When operating theatre and recovery ward equipment are taken into account, every hospital ought to be able to expand ICU capacity by 50 per cent if elective surgery is stopped. Consider the case for purchase of small amounts of additional equipment.

  9.  Identify the theatre and recovery staff theatre would be freed by above changes. These staff would be the first port of call for the ancillary ICU training identified by   3 above. See if this can allow expansion of ICU nursing numbers to allow staffing of 150 per cent of current capacity, even if there was a 25 per cent sickness/absenteeism rate in both cohorts of staff.

  10.  The DH should provide additional funds for medical and nursing staff to undertake core critical care medicine training, and find ways to ensure their willingness to be called in the event of an emergency (eg payment of a retainer to undergo initial and refresher training, and be available in the event of an emergency; these would be the equivalent of the Territorial Army for the hospital's critical care services).

  11.  There needs to be explicit statement and restatement of the principle that staff involved in the care of patients with influenza will receive the best available personal protection, in terms of vaccination, antivirals and personal protective equipment.

REFERENCES:

  1.  Menon DK, Taylor BL, Ridley SA. Intensive Care Society, UK. Modelling the impact of an influenza pandemic on critical care services in England. Anaesthesia 2005; 60: 952-954.

  2.  Zhang X, Meltzer MI, Wortley P. FluSurge 1.0: a manual to assist state and local public health officials and hospital administrators in estimating the impact of an influenza pandemic on hospital surge capacity (Beta test version). Centers for Disease Control and Prevention, U.S. Department of Health and Human Services; 2004. http://www.cdc.gov/flu/flusurge.htm

  3.  Mandell LA, Marrie TJ, Grossman RF et al. Summary of Canadian Guidelines for the initial management of community-acquired pneumonia: An evidence-based update by the Canadian Infectious Disease Society and the Canadian Thoracic Society. Can Respir J 2000; 7: 371-382.

  4.  Marrie TJ, Lau CY, Wheeler SL et al. A controlled trial of a Critical Pathway for treatment of community-acquired pneumonia. JAMA 2000; 283: 749-755.

  5.  Angus DC, Marrie TJ, Obrosky DS et al. Severe community-acquired pneumonia. Use of intensive care services and evaluation of American and British Society diagnostic criteria. Am J Respir Crit Care Med 2002; 166; 717-723.

  6.  Riley PD, Aronsky D, Dean NC. Validation of the 2001 American Thoracic Society criteria for severe community-acquired pneumonia. Chest 2004; 32: 2398-2402.

  7.  Halm EA, Horowitz C, Silver A, et al. Limited impact of a multicentre intervention to improve the quality and efficiency of pneumonia care. Chest 2004; 126: 100-107.

  8.  http://www.who.int/csr/disease/avian_influenza/country/cases_table_2005_10_20/en/index.html

  9.  Qureshi K, Gershon RR, Sherman MF, et al. Health care workers' ability and willingness to report to duty during catastrophic disasters. J Urban Health 2005; 82: 378_88.

  10.  Osterholm MT. Preparing for the next pandemic. N Engl J Med 2005; 352: 1839_1842.

  11.  Rubinson L, Nuzzo JB, Talmor DS, et al. Augmentation of hospital critical care capacity after bioterrorist attacks or epidemics: Recommendations of the Working Group on Emergency Mass Critical Care. Crit Care Med 2005; 33: 2393_2403.

  12.  Personal communication. Frances Chinemana, Access and Health Protection, NHS Direct.

27 October 2005


 
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