Avian influenza (H5N1): implications for intensive care

Selected microwave irradiation effectively inactivates airborne avian influenza A(H5N1) virus

The highly pathogenic avian influenza A(H5N1) virus threatens animal and human health globally. Innovative strategies are crucial for mitigating risks associated with airborne transmission and preventing outbreaks. In this study, we sought to investigate the efficacy of microwave inactivation against aerosolized A(H5N1) virus by identifying the optimal frequency band for a 10-min exposure and evaluating the impact of varying exposure times on virus inactivation. A(H5N1) was aerosolized and exposed to various microwave frequencies ranging from 8 to 16 GHz for a duration of 10 min. Viral titers were quantified using TCID50, and inactivation was assessed by comparing irradiated samples to controls. The 11-13 GHz band yielded the highest inactivation, with an average 89% mean reduction in A(H5N1) titer, particularly within the 11-12 GHz range, which exhibited peak efficacy. Based on the overall results, the optimal frequency band (8-12 GHz) was further tested with exposure durations of 1, 3, and 5 min. Inactivation was time-dependent, with a 5-minute exposure resulting in a 94% mean reduction, compared to 58% and 48% for 3- and 1-minute exposures, respectively. We conclude that optimized microwave emitters in high-risk environments like poultry farms and veterinary clinics could offer a novel, non-chemical approach to mitigating avian influenza spread and outbreaks.

Portable UV-C device to treat high flow of infectious aerosols generated during clinical respiratory care

Respiratory interventions including noninvasive ventilation, continuous positive airway pressure and high-flow nasal oxygen generated infectious aerosols may increase risk of airborne disease (SARS-CoV-2, influenza virus) transmission to healthcare workers. We developed and tested a prototype portable UV-C254 device to sterilize high flows of viral-contaminated air from a simulated patient source at airflow rates of up to 100 l/m. Our device consisted of a central quartz tube surrounded 6 high-output UV-C254 lamps, within a larger cylinder allowing recirculation past the UV-C254 lamps a second time before exiting the device. Testing was with nebulized A/PR/8/34 (H1N1) influenza virus. RNA extraction and qRT-PCR showed virus transited through the prototype. Turning on varying numbers of lamps controlled the dose of UVC. Viability experiments at low, medium and high (100 l/min) flows of contaminated gas were conducted with 6, 4, 2 and 1 lamp activated (single-pass and recirculation were tested). Our data show 5-log reduction in plaque forming units from a single lamp (single- pass and recirculated conditions) at high and low flows. UVC dose at 100 l/m was calculated at 11.6 mJ/cm2 single pass and 104 mJ/cm2 recirculated. The protype device shows high efficacy in killing nebulized influenza virus in a high flow of contaminated air.

Portable UV-C Device to Treat High Flow of Infectious Aerosols Generated during Clinical Respiratory Care

Respiratory interventions including noninvasive ventilation, continuous positive airway pressure and high-flow nasal oxygen generated infectious aerosols may increase risk of airborne disease (SARS-CoV-2, influenza virus) transmission to healthcare workers. We developed/tested a prototype portable UV-C254 device to sterilize high flows of viral-contaminated air from a simulated patient source at airflow rates of up to 100 l/m. Our device consisted of a central quartz tube surrounded 6 high-output UV-C254 lamps, within a larger cylinder allowing recirculation past the UV-C254 lamps a second time before exiting the device. Testing was with nebulized A/PR/8/34 (H1N1) influenza virus. RNA extraction and qRT-PCR showed virus transited through the prototype. Turning on varying numbers of lamps controlled the dose of UVC. Viability experiments at low, medium and high (100 l/min) flows of contaminated gas were conducted with 6, 4, 2 and 1 lamp activated (single-pass and recirculation were tested). Our data show 5-log reduction in particle forming units from a single lamp (single- pass and recirculated conditions) at high and low flows. UVC dose at 100 l/m was calculated at 11.6 mJ/cm2 single pass and 104 mJ/cm2 recirculated. The protype device shows high efficacy in killing nebulized influenza virus in a high flow of contaminated air.

Preventing Airborne Disease Transmission: Implications for Patients During Mechanical Ventilation

The organisms causing respiratory infections such as influenza are spread in droplets or aerosols or by direct or indirect contact with contaminated surfaces. Certain medical procedures have been termed aerosol generating because they are associated with high or augmented inspiratory and expiratory flows, which can increase microbial dissemination. Invasive ventilation maneuvers and noninvasive ventilation (NIV) fall into that category. We discuss the risk of transmitting these procedures and the strategies for mechanical ventilation in future airborne epidemics with special consideration given to the issue of protecting health care workers (HCWs).

A modified sequential organ failure assessment score for critical care triage

OBJECTIVE

The Sequential Organ Failure Assessment (SOFA) score has been recommended for triage during a mass influx of critically ill patients, but it requires laboratory measurement of 4 parameters, which may be impractical with constrained resources. We hypothesized that a modified SOFA (MSOFA) score that requires only 1 laboratory measurement would predict patient outcome as effectively as the SOFA score.

METHODS

After a retrospective derivation in a prospective observational study in a 24-bed medical, surgical, and trauma intensive care unit, we determined serial SOFA and MSOFA scores on all patients admitted during the 2008 calendar year and compared the ability to predict mortality and the need for mechanical ventilation.

RESULTS

A total of 1770 patients (56% male patients) with a 30-day mortality of 10.5% were included in the study. Day 1 SOFA and MSOFA scores performed equally well at predicting mortality with an area under the receiver operating curve (AUC) of 0.83 (95% confidence interval 0.81-.85) and 0.84 (95% confidence interval 0.82-.85), respectively (P = .33 for comparison). Day 3 SOFA and MSOFA predicted mortality for the 828 patients remaining in the intensive care unit with an AUC of 0.78 and 0.79, respectively. Day 5 scores performed less well at predicting mortality. Day 1 SOFA and MSOFA predicted the need for mechanical ventilation on day 3, with an AUC of 0.83 and 0.82, respectively. Mortality for the highest category of SOFA and MSOFA score (>11 points) was 53% and 58%, respectively.

CONCLUSIONS

The MSOFA predicts mortality as well as the SOFA and is easier to implement in resource-constrained settings, but using either score as a triage tool would exclude many patients who would otherwise survive.

A computationally optimized hemagglutinin virus-like particle vaccine elicits broadly reactive antibodies that protect nonhuman primates from H5N1 infection

BACKGROUND

Highly pathogenic H5N1 avian influenza viruses continue to spread via waterfowl, causing lethal infections in humans. Vaccines can prevent the morbidity and mortality associated with pandemic influenza isolates. Predicting the specific isolate that may emerge from the 10 different H5N1 clades is a tremendous challenge for vaccine design.

METHODS

In this study, we generated a synthetic hemagglutinin (HA) on the basis of a new method, computationally optimized broadly reactive antigen (COBRA), which uses worldwide sequencing and surveillance efforts that are specifically focused on sequences from H5N1 clade 2 human isolates.

RESULTS

Cynomolgus macaques vaccinated with COBRA clade 2 HA H5N1 virus-like particles (VLPs) had hemagglutination-inhibition antibody titers that recognized a broader number of representative isolates from divergent clades as compared to nonhuman primates vaccinated with clade 2.2 HA VLPs. Furthermore, all vaccinated animals were protected from A/Whooper Swan/Mongolia/244/2005 (WS/05) clade 2.2 challenge, with no virus detected in the nasal or tracheal washes. However, COBRA VLP-vaccinated nonhuman primates had reduced lung inflammation and pathologic effects as compared to those that received WS/05 VLP vaccines.

CONCLUSIONS

The COBRA clade 2 HA H5N1 VLP elicits broad humoral immunity against multiple H5N1 isolates from different clades. In addition, the COBRA VLP vaccine is more effective than a homologous vaccine against a highly pathogenic avian influenza virus challenge.

A porcine model for initial surge mechanical ventilator assessment and evaluation of two limited-function ventilators

OBJECTIVES

To adapt an animal model of acute lung injury for use as a standard protocol for a screening initial evaluation of limited function, or "surge," ventilators for use in mass casualty scenarios.

DESIGN

Prospective, experimental animal study.

SETTING

University research laboratory.

SUBJECTS

Twelve adult pigs.

INTERVENTIONS

Twelve spontaneously breathing pigs (six in each group) were subjected to acute lung injury/acute respiratory distress syndrome via pulmonary artery infusion of oleic acid. After development of respiratory failure, animals were mechanically ventilated with a limited-function ventilator (simplified automatic ventilator [SAVe] I or II; Automedx, Germantown, MD) for 1 hr or until the ventilator could not support the animal. The limited-function ventilator was then exchanged for a full-function ventilator (Servo 900C; Siemens-Elema, Solna, Sweden).

MEASUREMENTS AND MAIN RESULTS

Reliable and reproducible levels of acute lung injury/acute respiratory distress syndrome were induced. The SAVe I was unable to adequately oxygenate five animals with Pao2 (52.0±11.1 torr) compared to the Servo (106.0±25.6 torr; p=.002). The SAVe II was able to oxygenate and ventilate all six animals for 1 hr with no difference in Pao2 (141.8±169.3 torr) compared to the Servo (158.3±167.7 torr).

CONCLUSIONS

We describe a novel in vivo model of acute lung injury/acute respiratory distress syndrome that can be used to initially screen limited-function ventilators considered for mass respiratory failure stockpiles and that is intended to be combined with additional studies to definitively assess appropriateness for mass respiratory failure. Specifically, during this study we demonstrate that the SAVe I ventilator is unable to provide sufficient gas exchange, whereas the SAVe II, with several more functions, was able to support the same level of hypoxemic respiratory failure secondary to acute lung injury/acute respiratory distress syndrome for 1 hr.

Pandemic influenza: implications for preparation and delivery of critical care services

In a 5-week span during the 1918 influenza A pandemic, more than 2000 patients were admitted to Cook County Hospital in Chicago, with a diagnosis of either influenza or pneumonia; 642 patients, approximately 31% of those admitted, died, with deaths occurring predominantly in patients of age 25 to 30 years. This review summarizes basic information on the biology, epidemiology, control, treatment and prevention of influenza overall, and then addresses the potential impact of pandemic influenza in an intensive care unit setting. Issues that require consideration include workforce staffing and safety, resource management, alternate sites of care surge of patients, altered standards of care, and crisis communication.

Oseltamivir in seasonal, avian H5N1 and pandemic 2009 A/H1N1 influenza: pharmacokinetic and pharmacodynamic characteristics

Oseltamivir is the ester-type prodrug of the neuraminidase inhibitor oseltamivir carboxylate. It has been shown to be an effective treatment for both seasonal influenza and the recent pandemic 2009 A/H1N1 influenza, reducing both the duration and severity of the illness. It is also effective when used preventively. This review aims to describe the current knowledge of the pharmacokinetic and pharmacodynamic characteristics of this agent, and to address the issue of possible therapeutic drug monitoring. According to the currently available literature, the pharmacokinetics of oseltamivir carboxylate after oral administration of oseltamivir are characterized by mean ± SD bioavailability of 79 ± 12%, apparent clearance of 25.3 ± 7.0 L/h, an elimination half-life of 7.4 ± 2.5 hours and an apparent terminal volume of distribution of 267 ± 122 L. A maximum plasma concentration of 342 ± 83 μg/L, a time to reach the maximum plasma concentration of 4.2 ± 1.1 hours, a trough plasma concentration of 168 ± 32 μg/L and an area under the plasma concentration-time curve from 0 to 24 hours of 6110 ± 1330 μg · h/L for a 75 mg twice-daily regimen were derived from literature data. The apparent clearance is highly correlated with renal function, hence the dosage needs to be adjusted in proportion to the glomerular filtration rate. Interpatient variability is moderate (28% in apparent clearance and 46% in the apparent central volume of distribution); there is no indication of significant erratic or limited absorption in given patient subgroups. The in vitro pharmacodynamics of oseltamivir carboxylate reveal wide variation in the concentration producing 50% inhibition of influenza A and B strains (range 0.17-44 μg/L). A formal correlation between systemic exposure to oseltamivir carboxylate and clinical antiviral activity or tolerance in influenza patients has not yet been demonstrated; thus no formal therapeutic or toxic range can be proposed. The pharmacokinetic parameters of oseltamivir carboxylate after oseltamivir administration (bioavailability, apparent clearance and the volume of distribution) are fairly predictable in healthy subjects, with little interpatient variability outside the effect of renal function in all patients and bodyweight in children. Thus oseltamivir carboxylate exposure can probably be controlled with sufficient accuracy by thorough dosage adjustment according to patient characteristics. However, there is a lack of clinical study data on naturally infected patients. In addition, the therapeutic margin of oseltamivir carboxylate is poorly defined. The usefulness of systematic therapeutic drug monitoring in patients therefore appears to be questionable; however, studies are still needed to extend the knowledge to particular subgroups of patients or dosage regimens.

Epidemic viral pneumonia

PURPOSE OF REVIEW

Two recent viral epidemics producing pneumonitis (severe acute respiratory syndrome and pandemic influenza A H1N1) have highlighted the potential for viral infections to cause respiratory failure with a significant risk of mortality. This review describes these epidemics and other causes of epidemic viral pneumonia.

RECENT FINDINGS

The recent literature highlights the rapidity with which these emerging viral infections can be characterized and how management strategies, including supportive care, antiviral therapy and infection control precautions, can be rapidly shared and implemented.

SUMMARY

The severe acute respiratory syndrome outbreak was too short to allow management protocols to be tested in a research environment. The current 2009 influenza A (H1N1) pandemic is fortunately not associated with as high a mortality rate as the avian influenza A (H5N1), another potential pandemic candidate virus. Prior pandemic planning as well as research planning has allowed a rapid response to this outbreak, with a significant amount of literature generated in a few months. Other common seasonal viruses, such as respiratory syncytial virus and parainfluenza, as well as previously poorly recognized viruses such as hantavirus, have the ability to cause significant respiratory morbidity and mortality.

Pandemic influenza and pediatric intensive care

OBJECTIVE

To assess the adequacy of preparedness planning for an influenza pandemic by modeling the pediatric surge capacity of healthcare facility and pediatric intensive care unit (PICU) requirements over time. Governments and Public Health authorities have planned preparedness activities and training for a flu pandemic. PICU facilities will be the limiting factor in healthcare provision for children but detailed analyses for needs and demands in PICU care have not been published.

DESIGN

Based on the Center for Disease Control and Prevention and World Health Organization estimates and published models of the expected evolution of pandemic flu, we modeled the pediatric surge capacity of healthcare facility and PICU requirements over time. Various scenarios with different assumptions were explored. We compared these demands with estimates of maximal PICU capacity factoring in healthcare worker absenteeism as well as reported and more realistic estimates derived from semistructured telephone interviews with key stakeholders in ICUs in the study area.

SETTING

All hospitals and intensive care facilities in the Northern Region in The Netherlands with near 1.7 million inhabitants, of whom approximately 25% is <18 yrs.

MEASUREMENTS AND MAIN RESULTS

Using well-established modeling techniques, evidence-based medicine, and incorporating estimates from the Centers for Disease Control and Prevention and World Health Organization, we show that PICU capacity may suffice during an influenza pandemic. Even during the peak of the pandemic, most children requiring PICU admission may be served, even those who have nonflu-related conditions, provided that robust indications and decision rules are maintained, both for admission, as well as continuation (or discontinuation) of life support.

CONCLUSIONS

We recommend that a model, with assumptions that can be adapted with new information obtained during early stages of the pandemic that is evolving, be an integral part of a preparedness plan for a pandemic influenza with new human transmissible agent like influenza A virus.

Emergency department surge capacity: recommendations of the Australasian Surge Strategy Working Group

For more than a decade, emergency medicine (EM) organizations have produced guidelines, training, and leadership for disaster management. However, to date there have been limited guidelines for emergency physicians (EPs) needing to provide a rapid response to a surge in demand. The aim of this project was to identify strategies that may guide surge management in the emergency department (ED). A working group of individuals experienced in disaster medicine from the Australasian College for Emergency Medicine Disaster Medicine Subcommittee (the Australasian Surge Strategy Working Group) was established to undertake this work. The Working Group used a modified Delphi technique to examine response actions in surge situations and identified underlying assumptions from disaster epidemiology and clinical practice. The group then characterized surge strategies from their corpus of experience; examined them through available relevant published literature; and collated these within domains of space, staff, supplies, and system operations. These recommendations detail 22 potential actions available to an EP working in the context of surge, along with detailed guidance on surge recognition, triage, patient flow through the ED, and clinical goals and practices. The article also identifies areas that merit future research, including the measurement of surge capacity, constraints to strategy implementation, validation of surge strategies, and measurement of strategy impacts on throughput, cost, and quality of care.

[Organization of intensive care in situation of avian flu pandemic]

The influenza pandemic will create a major increase in demand for hospital admissions, particularly for critical care services. The recommendations detailed herein have been elaborated by experts from medical societies potentially involved in this situation and focus on general hospital organization. Intensive care units will initially face high demand for admission; the Healthcare Authorities must therefore study how ICU capacity can be expanded. Pediatric intensive care units will be particularly affected by this situation of relative bed shortage, since young children, particularly infants, are expected to be affected by severe clinical forms of avian flu. Therefore, the weight threshold for admission to the adult ICU was lowered to 20 kg. Neonatal intensive care units (NICU) should remain, if possible, low viral density areas. Mixed (neonatal and pediatric) intensive care units could be dedicated to infants and children only. NICU admission of extreme premature babies should be limited in this difficult situation. Pediatric intensive care units (PICU) admission capacity could be doubled by using intermediate care and postoperative care units. The staff could be increased by doctors and nurses involved in canceled programmed activities. Healthcare workers transferred to PICU should be given special training.

Mechanical ventilation in an airborne epidemic

With the increasing threat of pandemic influenza and catastrophic bioterrorism, it is important for intensive care providers to be prepared to meet the challenge of large-scale airborne epidemics causing mass casualty respiratory failure. The severe acute respiratory syndrome outbreak exposed the vulnerability of health care workers and highlighted the importance of establishing stringent infection control and crisis management protocols. Patients who have acute lung injury and acute respiratory distress syndrome who require mechanical ventilation should receive a lung protective, low tidal volume strategy. Controversy remains regarding the use of high-frequency oscillatory ventilation and noninvasive positive pressure ventilation. Standard, contact, and airborne precautions should be instituted in intensive care units, with special care taken when aerosol-generating procedures are performed.

Influenza A/H5N1 infection: other treatment options and issues

Antiviral therapy and vaccination are important strategies for the control of human influenza/H5N1 disease, but the efficacy of these modalities is limited by timing of administration and shortage of supply. Lung protective ventilation strategy with a low tidal volume and low pressure, in addition to a conservative fluid management approach, is recommended when treating patients with ARDS. Low-dose steroids may be considered in the treatment of refractory septic shock. Non-invasive positive pressure ventilation (NPPV) may play a limited supportive role for early ARDS/acute lung injury, but it is contra-indicated in critically ill patients with multi-organ failure and haemodynamic instability. NPPV and oxygen therapy should be applied in healthcare facilities with good ventilation and respiratory protection as substantial exposure to exhaled air occurs within a 0.5 m and 0.4 m radius of patients receiving NPPV and oxygen via a simple mask, respectively. Intravenous gammaglobulin should be used with caution for treatment of reactive haemo-phagocytosis due to its thrombogenic effects, whereas the role of etoposide needs evaluation with animal models. Passive immunotherapy in the form of convalescent plasma may be useful as rescue therapy. More data are needed to explore the potential role of other drugs with immuno-modulating properties such as statins. Healthcare workers currently must apply strict standards, contact and droplet precautions when dealing with suspected cases, and upgrade to airborne precautions when performing aerosol-generating procedures. Non-pharmacological measures such as early case isolation, household quarantine, school/workplace closure, good community hygiene and restrictions on travel are useful measures in controlling a pandemic.

Intensive care management of life-threatening avian influenza A (H5N1)

A large proportion of patients with avian influenza A (H5N1) develop life-threatening manifestations, often including ARDS, acute renal failure and multiple organ failure that requires aggressive intensive care management. The pace of development of respiratory failure is often rapid and can occur in previously healthy hosts, mandating close observation and timely intervention of infected individuals. Use of standard, contact, droplet and airborne isolation precautions is recommended to protect healthcare workers. Key components of ARDS management encompass appropriate mechanical ventilation including limiting tidal volume to </=6 mL/kg of predicted body weight, maintaining transpulmonary pressures </=30 cm H(2)O, and utilizing positive end-expiratory pressure to limit alveolar deflation and to improve oxygenation. Additional strategies include conservative fluid management and using nutrition supplemented with antioxidants. Use of corticosteroids is controversial for both early and late ARDS and although often used for avian influenza, beneficial effects on outcomes have not been demonstrated for corticosteroids. Prone positioning can improve oxygenation temporarily and might be useful as rescue therapy for severe hypoxemia. Administration of inhaled nitric oxide and high frequency oscillatory ventilation can improve oxygenation but have not been demonstrated to improve survival in ARDS-their role in avian influenza is uncertain and availability limited. Management of multiple organ failure may include vasopressor support for septic shock and renal replacement therapy for acute renal failure.

Review of clinical symptoms and spectrum in humans with influenza A/H5N1 infection

Influenza A/H5N1 infection has become the major emerging infectious disease of global concern again since late 2003. A history of exposure to dead or sick poultry or wild birds occurs in over 60% of cases of human H5N1 infection. The incubation period of avian-to-human transmission is generally between 2 and 5 days and the median duration of symptoms before hospitalization is about 4.5 days. The clinical spectrum has ranged from asymptomatic infection or mild influenza-like illness to severe pneumonia and multi-organ failure. Fever > 38 degrees C, cough and dyspnoea are the major symptoms on presentation, whereas gastrointestinal symptoms such as watery diarrhoea, vomiting and abdominal pain are common early in the course of the disease. In contrast, upper respiratory tract symptoms are less prominent in human H5N1 infection when compared to seasonal influenza. Laboratory features of human H5N1 infection include leucopoenia, especially lymphopenia, elevated amino-transaminases, thrombocytopenia, prolonged prothrombin time and activated partial thromboplastin time, increased D-Dimer, increased serum lactate dehydrogenase and creatinine phospho-kinase, and hypoalbuminemia. A low absolute lymphocyte count on admission is associated with more severe disease and death. Radiographic abnormalities include multi-focal airspace consolidation, interstitial infiltrates, patchy or lobar involvement, with rapid progression to bilateral and diffuse ground-glass opacities consistent with ARDS. However, none of the clinical, laboratory and radiographic features are specific to H5N1 infection. A detailed exposure history needs to be elicited, including any close contact with sick or dead poultry, wild birds, other severely ill persons, travel to an area with A/H5N1 activity or work in laboratory handling samples possibly containing A/H5N1 virus.

Acute febrile respiratory illness in the ICU: reducing disease transmission

Acute febrile respiratory illness (FRI) leading to respiratory failure is a common reason for admission to the ICU. Viral pneumonia constitutes a portion of these cases, and often the viral etiology goes undiagnosed. Emerging viral infectious diseases such as severe acute respiratory syndrome and avian influenza present with acute FRIs progressing to respiratory failure and ARDS. Therefore, early recognition of a viral cause of acute FRI leading to ARDS becomes important for protection of health-care workers (HCWs), lessening spread to other patients, and notification of public health officials. These patients often have longer courses of viral shedding and undergo higher-risk procedures that may potentially generate aerosols, such as intubation, bronchoscopy, bag-valve mask ventilation, noninvasive positive pressure ventilation, and medication nebulization, further illustrating the importance of early detection and isolation. A small number of viral agents lead to acute FRI, respiratory failure, and ARDS: seasonal influenza, avian influenza, coronavirus associated with severe ARDS, respiratory syncytial virus, adenovirus, varicella, human metapneumovirus, and hantavirus. A systematic approach to early isolation, testing for these agents, and public health involvement becomes important in dealing with acute FRI. Ultimately, this approach will lead to improved HCW protection, reduction of transmission to other patients, and prevention of transmission in the community.

[The organisation of intensive care in a situation of pandemic avian influenza]

The development of an epidemic of avian influenza will have a major impact on the organisation and structure of the facilities for treatment. This paper, the product of collaboration between the six learned societies concerned, analyses the impact of a possible pandemic on the various aspects of management of patients requiring intensive care. It describes the organisation of hospital pathways for flu and non-flu patients with, in particular, the necessary actions in terms of separation of care facilities, the triage of patients and the cancellation of non-urgent activities. It analyses the preconditions necessary for the efficient functioning of intensive care and the predictable limiting factors. It underlines the importance of training of medical and paramedical personnel. Finally, it tackles the specific problems of paediatric intensive care: organisation, capacity for admissions and training.

Mass-casualty incidents: how does an ICU prepare?

Despite the ever-present risk of mass-casualty incidents (MCIs) in all geographical regions, there is a limited body of literature detailing specifically how an intensive care unit (ICU) prepares for such an event. When responding to an overwhelming volume of severely injured victims, the intensivist must make a paradigm shift away from providing complete care to all patients to one of preferentially administering care to those with the greatest likelihood of survival. To do this effectively, ICU directors must possess a detailed understanding of the entire disaster response, including organization, triage, staffing, and treatment. This article provides a comprehensive review of each of these topics, as well as a framework on specific elements of critical care and treatment based on published literature and expert opinion to assist the clinician in directing care to where it is most appropriate.

Definitive care for the critically ill during a disaster: medical resources for surge capacity: from a Task Force for Mass Critical Care summit meeting, January 26-27, 2007, Chicago, IL

BACKGROUND

Mass numbers of critically ill disaster victims will stress the abilities of health-care systems to maintain usual critical care services for all in need. To enhance the number of patients who can receive life-sustaining interventions, the Task Force on Mass Critical Care (hereafter termed the Task Force) has suggested a framework for providing limited, essential critical care, termed emergency mass critical care (EMCC). This article suggests medical equipment, concepts to expand treatment spaces, and staffing models for EMCC.

METHODS

Consensus suggestions for EMCC were derived from published clinical practice guidelines and medical resource utilization data for the everyday critical care conditions that are anticipated to predominate during mass critical care events. When necessary, expert opinion was used. TASK FORCE MAJOR SUGGESTIONS: The Task Force makes the following suggestions: (1) one mechanical ventilator that meets specific characteristics, as well as a set of consumable and durable medical equipment, should be provided for each EMCC patient; (2) EMCC should be provided in hospitals or similarly equipped structures; after ICUs, postanesthesia care units, and emergency departments all reach capacity, hospital locations should be repurposed for EMCC in the following order: (A) step-down units and large procedure suites, (B) telemetry units, and (C) hospital wards; and (3) hospitals can extend the provision of critical care using non-critical care personnel via a deliberate model of delegation to match staff competencies with patient needs.

DISCUSSION

By using the Task Force suggestions for adequate supplies of medical equipment, appropriate treatment space, and trained staff, communities may better prepare to deliver augmented essential critical care in response to disasters.

Clinical review: update of avian influenza A infections in humans

Influenza A viruses have a wide host range for infection, from wild waterfowl to poultry to humans. Recently, the cross-species transmission of avian influenza A, particularly subtype H5N1, has highlighted the importance of the non-human subtypes and their incidence in the human population has increased over the past decade. During cross-species transmission, human disease can range from the asymptomatic to mild conjunctivitis to fulminant pneumonia and death. With these cases, however, the risk for genetic change and development of a novel virus increases, heightening the need for public health and hospital measures. This review discusses the epidemiology, host range, human disease, outcome, treatment, and prevention of cross-transmission of avian influenza A into humans.

Pandemic preparedness

PURPOSE OF REVIEW

Pandemic influenza remains a threat to world health and will probably result in an overwhelming number of critically ill patients. Preparations should be made now to meet this threat.

RECENT FINDINGS

Limited data are available on which to base preparations. Adequate staffing is crucial to the functioning of an ICU and therefore occupational safety is of central concern. In the absence of knowledge of the method of spread of a pandemic disease, it would seem appropriate to take airborne and contact precautions, and the literature related to this area is reviewed. Methods of recruiting and training additional staff and the issues of bed capacity, stockpiling, triage and ethics are discussed.

SUMMARY

Extensive preparation is needed in advance of an epidemic. This should include occupational safety measures, stockpiling of equipment and drugs, staff training, development of triage policies, and discussion of the limits of duty of care to patients. These preparations take considerable time and therefore these issues should be tackled urgently.

Pandemic influenza and hospital resources

Using estimates from the Centers for Disease Control and Prevention, the World Health Organization, and published models of the expected evolution of pandemic influenza, we modeled the surge capacity of healthcare facility and intensive care unit (ICU) requirements over time in northern Netherlands (approximately 1.7 million population). We compared the demands of various scenarios with estimates of maximum ICU capacity, factoring in healthcare worker absenteeism as well as reported and realistic estimates derived from semistructured telephone interviews with key management in ICUs in the study area. We show that even during the peak of the pandemic, most patients requiring ICU admission may be served, even those who have non-influenza-related conditions, provided that strong indications and decision-making rules are maintained for admission as well as for continuation (or discontinuation) of life support. Such a model should be integral to a preparedness plan for a pandemic with a new human-transmissible agent.

The critically ill avian influenza A (H5N1) patient

OBJECTIVE

This review examines perspectives of human infection with avian influenza A H5N1 (AI H5N1), specifically focusing on the presentation, diagnosis, and management of those critically ill with AI H5N1.

DATA SOURCE

PubMed (1966-2006), PubMed "related articles," publications and Web sites of the World Health Organization and the Centers for Disease Control and Prevention, personal files, abstract proceedings, and reference lists.

STUDY SELECTION

We reviewed English-language publications pertaining to clinical presentation, diagnosis, and management of AI H5N1 and infection control expressly relating to the intensive care setting.

DATA SYNTHESIS

The majority of reported patients with AI H5N1 are critically ill and require intensive care management. These patients progress rapidly to severe acute respiratory distress syndrome. Multiorgan failure occurs in a large proportion. Because of the nonspecific clinical, laboratory, and radiologic features, it is critical to seek a history of exposure to poultry or wild birds in suspected cases. Reverse transcription polymerase chain reaction performed on nasopharyngeal aspirate is the most reliable method for the laboratory diagnosis of AI H5N1. Treatment includes starting neuraminidase inhibitor oseltamivir as early as possible in addition to the standard supportive management. Aerosol generating procedures should be minimized to avoid nosocomial transmission. Strict infection control procedures are paramount to staff safety, although human-to-human transmission is rare as of this time.

CONCLUSIONS

Many patients with AI H5N1 are critically ill either at presentation or shortly thereafter. Intensivists and intensive care units are therefore at the front line for this new cause of severe lung injury. Practitioners must be familiar with the nonspecific presentation of AI H5N1 and its diagnostic and therapeutic options. Although treating the infected patient with AI H5N1 is a priority, safeguarding healthcare workers and other patients must be considered of equal priority.

The prospect of using alternative medical care facilities in an influenza pandemic

Alternative care facilities (ACFs) have been widely proposed in state, local, and national pandemic preparedness plans as a way to address the expected shortage of available medical facilities during an influenza pandemic. These plans describe many types of ACFs, but their function and roles are unclear and need to be carefully considered because of the limited resources available and the reduced treatment options likely to be provided in a pandemic. Federal and state pandemic plans and the medical literature were reviewed, and models for ACFs being considered were defined and categorized. Applicability of these models to an influenza pandemic was analyzed, and recommendations are offered for future ACF use. ACFs may be best suited to function as primary triage sites, providing limited supportive care, offering alternative isolation locations to influenza patients, and serving as recovery clinics to assist in expediting the discharge of patients from hospitals.

Update on Avian Influenza for Critical Care Physicians

Human influenza pandemics over the last 100 years have been caused by H1, H2, and H3 subtypes of influenza A viruses. More recently, avian influenza viruses have been found to directly infect humans from their avian hosts. The recent emergence, host expansion, and spread of a highly pathogenic avian influenza (HPAI) H5N1 subtype in Asia has heightened concerns globally, both in regards to mortality of HPAI H5N1 in humans and the potential of a new pandemic. In response, many agencies and organizations have been working collaboratively to develop early detection systems, preparedness plans, and objectives for further research. As a result, there has been a large influx of published information regarding potential risk, surveillance, prevention and control of highly pathogenic avian influenza, particularly in regards to animal to human and subsequent human to human transmission. This chapter will review the current human infections with avian influenza and its public health and medical implications.

Critical Care Pandemic Preparedness Primer

The first half decade of the 21^st century has brought with it infectious outbreaks such as severe acute respiratory syndrome (SARS) [1], bioterrorism attacks with anthrax [2], and the spread of H5N1 influenza A in birds across Asia and Europe [3, 4] sparking concerns reminiscent of the days of the Black Plague. These events, in the context of an instantaneous global-media world, have placed an unprecedented emphasis on preparing for a human influenza pandemic [5, 6]. Although some argue that the media have exaggerated the threat, the warnings of an impending pandemic are not without foundation given the history of past influenza pandemics [7], incidence of H5N1 infections among humans [8], and the potential impact of a pandemic. Reports of the 1918 pandemic vary, but most suggested that approximately one third of the world’s population was infected with 50 to 100 million deaths [9]. Computer modeling of a moderate pandemic, less severe then in 1918, in the province of Ontario, Canada predicts 73,252 admissions of influenza patients to hospitals over a 6-week period utilizing 72% of the hospital capacity, 171% of intensive care unit (ICU) capacity, and 118% of current ventilator capacity. Pandemic modeling by the Australian and New Zealand Intensive Care Society also showed that critical care resources would be overwhelmed by even a moderate pandemic [10]. This chapter will provide intensivists with a review of the basic scientific and clinical aspects of influenza as well as an introduction to pandemic preparedness.

Update on Avian Influenza for Critical Care Physicians

Human influenza pandemics over the last 100 years have been caused by H1, H2, and H3 subtypes of influenza A viruses. More recently, avian influenza viruses have been found to directly infect humans from their avian hosts. The recent emergence, host expansion, and spread of a highly pathogenic avian influenza (HPAI) H5N1 subtype in Asia has heightened concerns globally, both in regards to mortality of HPAI H5N1 in humans and the potential of a new pandemic. In response, many agencies and organizations have been working collaboratively to develop early detection systems, preparedness plans, and objectives for further research. As a result, there has been a large influx of published information regarding potential risk, surveillance, prevention and control of highly pathogenic avian influenza, particularly in regards to animal to human and subsequent human to human transmission. This chapter will review the current human infections with avian influenza and its public health and medical implications.

Critical Care Pandemic Preparedness Primer

The first half decade of the 21^st century has brought with it infectious outbreaks such as severe acute respiratory syndrome (SARS) [1], bioterrorism attacks with anthrax [2], and the spread of H5N1 influenza A in birds across Asia and Europe [3, 4] sparking concerns reminiscent of the days of the Black Plague. These events, in the context of an instantaneous global-media world, have placed an unprecedented emphasis on preparing for a human influenza pandemic [5, 6]. Although some argue that the media have exaggerated the threat, the warnings of an impending pandemic are not without foundation given the history of past influenza pandemics [7], incidence of H5N1 infections among humans [8], and the potential impact of a pandemic. Reports of the 1918 pandemic vary, but most suggested that approximately one third of the world’s population was infected with 50 to 100 million deaths [9]. Computer modeling of a moderate pandemic, less severe then in 1918, in the province of Ontario, Canada predicts 73,252 admissions of influenza patients to hospitals over a 6-week period utilizing 72% of the hospital capacity, 171% of intensive care unit (ICU) capacity, and 118% of current ventilator capacity. Pandemic modeling by the Australian and New Zealand Intensive Care Society also showed that critical care resources would be overwhelmed by even a moderate pandemic [10]. This chapter will provide intensivists with a review of the basic scientific and clinical aspects of influenza as well as an introduction to pandemic preparedness.