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Intensive Care implications

Up Features & treatment Intensive Care implications References


Pascale Gruber, Charles Gomersall, Gavin Joynt

First posted 224th April 2006

This page is based on: Gruber PC, Gomersall CD, Joynt GM. Avian influenza (H5N1): implications for intensive care, published in Intensive Care Medicine. Reproduced here, in part, with the permission of Springer Verlag. Click here to download the published version (requires subscription).

As influenza A/H5N1 spreads around the globe the risk of an epidemic increases. Review of the cases of influenza A/H5N1 reported to date suggests that it causes a severe illness. The infectious nature, severity and clinical manifestations of the disease and its potential for pandemic spread have considerable implications for Intensive Care in terms of infection control, patient management, staff morale and Intensive Care expansion.

Infection control

  • Even in the absence of efficient human-human transmission the consequences of transmission are potentially catastrophic because of the severity of the disease and the risk of genetic reassortment.

  • Click here for recommendations on preparation of infection control facilities in Intensive Care Units [31]

  • Infection control guidelines from the World Health Organization and Centers for Disease Control and Prevention recommend the use of standard, contact and airborne protection including respirators of N95 standard or higher [32,33]. However, the United Kingdom guidelines recommend the use of surgical masks with FFP3 (N100 equivalent) respirators only for aerosol generating procedures [34]. We believe that the WHO and CDC guidelines are more appropriate given the frequency of aerosol generating procedures in ICU, the risk of accidental disconnection of ventilator circuits, the high mortality associated with avian influenza and the relatively ineffective filtration provided by surgical masks [35]. Furthermore surgical masks were ineffective in controlling the spread of Spanish flu [36].

  • Once efficient human-human transmission occurs, based on data from human influenza viruses, it will have to be assumed that even asymptomatic individuals may be infectious and quarantine of healthcare workers will be necessary.

Centralized vs decentralized resources

Admission of all cases to an infectious diseases referral centre may have advantages in terms of ensuring adequate isolation and laboratory facilities, minimization of risk of human to human transmission and acquisition of expertise in managing the disease. However the rapid progression of disease and requirement for advanced organ support means that the timeframe available for safe transport of the patient is short.

Equipment

The high incidence of ARDS and pneumothorax has implications for the type of ventilators that should be stockpiled for use in an epidemic and ventilatory management.

  • Low volume low pressure strategy for ventilation of patients with ARDS has been shown to reduce mortality with a number needed to treat of 4.52 [37].

  • Although lung recruitment and the level of PEEP have not be proven to alter outcome [38,39], current expert opinion favours the use of recruitment manoeuvres and titration of PEEP to individual patient requirements [40].

It is, therefore, appropriate to stockpile ventilators capable of accurate measurement of tidal volume, plateau pressure and intrinsic PEEP and that will allow accurate titration of extrinsic PEEP, militating against purchase of simple transport ventilators. The high incidence of pneumothorax dictates a cautious approach to lung recruitment.

Given the high incidence of ARDS it is unlikely that non-invasive ventilation (NIV) will provide substantial benefit [41,42,43]. As there are concerns that non-invasive ventilation will increase the risk of disease transmission [31,47] the risk:benefit ratio does not favour use of NIV. In addition haemodynamic instability is a relative contraindication to NIV and cardiovascular failure is common in avian flu.

Paediatrics

A disproportionately large number of children are affected by avian influenza making it likely that paediatric ICU services will be rapidly overwhelmed. As a result adult ICUs need to stockpile appropriate equipment for managing paediatric patients and adult healthcare workers will need prior training in essential aspects of paediatric intensive care.

Time for preparation

The short time between hospital and ICU admission (median 2 days) and the high requirement for advanced organ support (63% of all reported patients) means that there will be limited time for preparation in the event of an epidemic. Many preparations are time consuming and need to be made in advance [31,48,49] We have previously recommended that additional staff should be trained to work in expanded ICUs, suggesting initial courses followed by refresher courses in the event of an outbreak [31]. In the case of avian influenza this may not be appropriate as there may be insufficient time to hold refresher courses once the outbreak becomes apparent.

Expansion of Intensive Care

Two recent publications have addressed the issue of expansion of Intensive Care in an epidemic. Rubinson et al have made recommendations based on the premise that provision of a lower level of Intensive Care to more patients is preferable to provision of a higher level of care to fewer patients [48]. We have taken a different approach and have made recommendations on how to expand Intensive Care without a significant reduction in quality of care [31]. While both approaches have merits in different situations we believe that the nature of avian influenza make the low level approach less suitable. The mortality of cases requiring advanced life support is 90% and the incidence of multiorgan failure is high. Given the complexity of cases it is likely that a reduction in the level of Intensive Care would result in a substantial rise in mortality. This could raise mortality to the point that it becomes questionable whether, on the basis of triage, patients with avian influenza should be admitted to ICU [50]. Indeed, even at the current 90% mortality diversion of resources from other critically ill patients is only justified by the young age of the patients with avian influenza. Age per se is unimportant but it would reasonable to expect young survivors to have a long life expectancy. Furthermore the small benefit to patients may not justify the risk to staff. We believe, therefore, that ICUs may only have a useful role in relatively small avian flu epidemics (assuming the epidemic form is as pathogenic as the current form) in which an increase in ICU capacity of 50-100% would be sufficient and that contingency plans should be made on that basis. In larger epidemics it may be more appropriate to re-deploy ICU staff to care for less severely ill patients. There are currently insufficient data to determine which patients with avian influenza should be admitted to Intensive Care and which should be refused.

Staff morale

Staff morale is important in an epidemic [31]. Poor morale may lead to high absenteeism which will have a severe impact on the provision of services. The high mortality rate and the high proportion of children may exacerbate morale issues and the need for staff counseling. The need to support bereaved parents will further increase the need for counseling services and preparations to meet this demand should be made.


©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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