Weight ranges of the patients in each age category were assumed to be consistent with data from the National Center for Health Statistics (http://www.cdc.gov/growthcharts, 2000). Mass critical care equipment size ranges were then planned for each age group, consistent with American Heart Association recommendations on weight-appropriate equipment sizes (4). Pediatric equipment lists for mass critical care are provided for two types of patients. For purposes of planning, it is arbitrarily assumed that 25% of the patients would have disorders unrelated to the public health emergency and would represent patients across the usual age category distribution, with equipment size distribution as described earlier. However, 75% of the patients would represent a public health emergency surge and would come entirely from any one of the six age categories. Thus, larger equipment stockpiles would be necessary to serve the largest need for each size item, across any of the age groups. This complete list would be more expensive to purchase and would result in some redundant, unused items, but large numbers of patients from any narrow age group would be adequately served (Table 3).
5) For most equipment, it is assumed that a single item per patient will serve throughout the patient's PICU stay.
Exceptions include the following: 1.5 endotracheal tubes/patient to account for patients needing reintubation; ten peripheral intravenous catheters/patient to account for unsuccessful attempts and the need for new catheters to replace infiltrated catheters during the PICU stay; one central venous catheter for every two patients; and one chest tube for every four patients.
The recommended size-specific pediatric mass critical care equipment stockpile is expressed as equipment needs per ten mass critical care beds, which would serve 26 patients over a 10-day period (Tables 2 and 3). Some specific comments should be noted. At a minimum, cardiac, apnea, and oximeter monitoring should be provided. Of course, usual complete PICU monitoring, including invasive pressures and end-tidal CO2, would be desirable, when available. However, in a mass critical care situation, central venous catheters may be more important for reliable vascular access than for monitoring (5). Pediatric-size self-inflatable ventilation bags should be provided for infants and children, since infant-size bags cannot be used to ventilate a larger infant, toddler, or child. Cuffed endotracheal tubes are recommended to avoid wasting a small tube when it is necessary to upsize the uncuffed tube that has an unacceptably large airleak. Cuffed tubes also allow a reduced inventory of sizes to accommodate all patient ages. Blood pressure cuffs are assumed to be reusable for the next patient after cleaning. Approximately three laryngoscope sets with all sizes of blades would serve each ten beds and allow time for resterilization. It is important to avoid environmental cold stress in burn patients and small infants. Radiant warmers already available at a hospital may be supplemented by ancillary equipment to warm entire rooms serving multiple patients.
Many other hospital equipment and supply items, including beds, linen, bedpans, and tape, are not detailed here but are essential for care in any hospital location. As recommended by the adult task force, when equipment resources are depleted, it may be necessary to resterilize and reuse equipment that is usually disposable.
Previously published specifications and guidelines on mechanical ventilation capabilities and oxygen supply requirements to address adult mass critical care needs are equally relevant to pediatric patients and are not repeated here (1). However, several specific concerns related to any equipment planning exercise for pediatric mass critical care must be addressed taking into account the following: 1) whether the pediatric hospital is a stand-alone facility or part of an adult facility with a shared ventilator inventory; 2) mechanical ventilation capability must be technically suitable across the pediatric age and development spectrum, from newborns to adolescents effectively of adult body mass; 3) consideration must also be given to more sophisticated life-sustaining treatment capabilities across the pediatric age and development spectrum, such as the use of high-frequency oscillatory ventilation; and 4) the development of a regional plan to establish reliable communication among tertiary care PICUs for sharing of resources, as needed, including transport facilities and equipment on site to move patients to a higher level of care. Even in a stand-alone pediatric hospital, it may be necessary to adapt transport ventilators, anesthesia ventilators, and bilevel positive pressure breathing devices for use in the PICU. Temporary manual bag ventilation may be necessary if there is a short delay in obtaining a ventilator or in the event of electrical power failure.
Some children's hospitals have supplies of ventilators with the necessary software and circuits for use in any patient across the entire size and age spectrum. In other hospitals, adult ventilators may have to be adapted for use in infants. The following difficulties may be encountered in using adult ventilators in small infants:
- The inspiratory flow or pressure sensor may be insensitive to an infant's small inspiratory air flow and effort. Thus, triggering of assisted inspiration may fail for synchronized intermittent mandatory ventilation, assist control, or pressure support. Likewise, when inspiratory flow for spontaneous breathing between ventilator breaths requires activation of a demand valve, an infant's small inspiratory air flow and effort may be inadequate to trigger demand flow.
- Ventilator algorithms to terminate pressure support inspiration may fail in the presence of airleaks around an endotracheal tube. Airleaks around an endotracheal tube may activate frequent ventilator alarms for low pressure and/or low exhaled tidal volume.
- In a volume-controlled mode, adult ventilators may be unable to provide small tidal volumes and reduced inspiratory flow rates appropriate for a small infant.
- Pressure-dependent losses of tidal volume in compressible spaces of compliant adult ventilator circuits exaggerate breath-to-breath variation in delivered tidal volume, especially if peak inspiratory pressure varies with patient effort and respiratory mechanics. Effectively providing small tidal volumes may be facilitated by use of time-cycled, pressure-limited mode of ventilation.
Given the relatively small number of PICUs compared to hospitals designed to care for critically ill adult patients, the formalization of a regional pediatric critical care referral system becomes a high priority when planning for mass casualties. A 2007 inventory of U.S. hospitals estimated that there are 62,188 full-feature ventilators owned by acute care hospitals (6). This amounts to 20.5 ventilators per 100,000 total population, or 0.7 ventilators per total intensive care unit beds. However, variation among states is wide (12–78/100,000 population). Forty-six percent of the full-feature ventilators are said to have pediatric-neonatal capability, amounting to 50.7 with age-appropriate capability per 100,000 children younger than 14 yrs (range among states is 22–206/100,000 pediatric population). In addition, an estimated 98,738 other ventilators are owned by acute care hospitals, including transport, older generation, and noninvasive devices. The inventory did not include ventilators owned by rental companies, nursing and rehabilitation facilities, stored in stockpiles, or in chronic home use. The estimated availability of ventilators in the United States is substantially greater than previously published estimates for Australia, New Zealand, and Ontario, Canada. Wide statewide variation in ventilator availability requires regional inventories to enable operational planning for mass critical care. Table 4 is an example of such an inventory developed by the PICUs in New England and could be used as a template for other regions.
Alternative modes of ventilation
In many tertiary care pediatric centers, alternative ventilation strategies, such as high-frequency oscillatory ventilation and extracorporeal membrane oxygenation (ECMO), are used as rescue therapies in children with acute hypoxic respiratory failure that cannot be reversed with conventional ventilation and positive end-expiratory pressure. Planning in these centers should include a regional stockpile of oscillators that could be accessed during a major surge. High-frequency oscillatory ventilation is a technique that could be learned and adopted in a crisis requiring a surge in capacity to care for critically ill children with the guidance of regional experts in this mode of ventilation. However, in the event of a pandemic of respiratory illness, the use of conventional ventilators allows for a greater number of patients to be treated.
The use of ECMO in a mass critical care setting is more problematic given that, as currently structured, it requires more resource utilization above and beyond the amount needed for conventional mechanical ventilation or high-frequency oscillatory ventilation. ECMO has been used in the ordinary surge circumstances of the 2009 Influenza A/H1N1 Pandemic, although the adult task force did not address the use of ECMO as an option for severe acute respiratory distress syndrome/hypoxic respiratory failure during a mass critical care situation. Despite this, it was extensively used in adults during the 2009 Influenza A/H1N1 epidemic in Australasia (7). ECMO is offered in the treatment of single-system pulmonary disease, unresponsive to conventional treatment, in many tertiary care pediatric centers. The overall survival of 48% where it was used in pediatric patients during the 2009 pandemic will continue to make this a controversial issue (www.elso.med.umich.edu/H1N1Registry). The accepted standard for staffing of one ECMO patient is one nurse and one ECMO specialist per patient, as well as the immediate availability of a senior specialist in pediatric critical care. This could be altered to a single-caregiver model in the event of a surge situation. However, unlike the 2009 pandemic surge, mass critical care involves a tripling of PICU capacity with altered levels of care, which would involve one PICU nurse supervising non-PICU supplement providers caring for perhaps three to six patients. It is therefore unlikely that ECMO would be available as a therapeutic option. A model of decision making for pandemics of acute respiratory illness based on available resources is provided in Figure 1.
Lessons from the 2009 Influenza A/H1N1 Pandemic
Pediatric mass critical care crises are more likely to arise from pandemics of acute respiratory illness. However, there is little experience of mass critical care during pandemics of respiratory illness in children on which to base planning assumptions for equipment and supplies. The severe acute respiratory syndrome pandemic in 2003 resulted in very few seriously ill children admitted to intensive care units (8). The 2009 Influenza A/H1N1 pandemics of April to June 2009 in the northern and southern hemispheres revealed that the highest age-specific incidence of the disease was in children younger than 4 yrs. Approximately 10% to 20% of children admitted to pediatric hospitals were transferred to intensive care, and the majority of these required positive-pressure ventilation (9–16). Many PICUs experienced a doubling of children admitted with respiratory failure, and a significant number also had hemodynamic compromise compared with the usual numbers of patients with seasonal flu. The experience in the second wave of the disease seen in North America in October and November 2009 was similar and in no instance invoked a mass critical care response.
Medications necessary to provide mass critical care have been suggested by the adult Mass Critical Care Task Force (17), but we lack evidence to guide quantitative recommendations. Essential categories include sedatives, analgesics, paralytics, bronchodilators, crystalloids, vasopressors, antimicrobials, selected antidotes, insulin, and glucocorticoids. Experience suggests that the need for analgesics may quickly exhaust usual stockpiles even in modest and temporary public health emergencies (18).
The usual numbers of critical care staff may be insufficient to meet the needs of a mass critical care surge. If available, supplemental providers with skills in nonpediatric critical care, or noncritical care pediatrics, may bring invaluable assistance to pediatric mass critical care. These may include physicians, nurse practitioners, physician assistants, nurses, respiratory therapists, pharmacists, and emergency medical technicians, particularly those having backgrounds in certain surgical subspecialties, anesthesia, and emergency medicine. Residents, medical students, and veterinary practitioners should also be considered in the event of a national pandemic situation. An altered or “crisis” standard of care would need to be adopted. Rapid credentialing procedures, just-in-time training, and close supervision by experienced PICU clinicians would promote the effective role of supplemental providers. The regulations governing work hours for physicians would need to be suspended. The Accreditation Council for Graduate Medical Education should consider the relaxation of duty hour restrictions during a national pandemic.
As suggested by the adult task force (19), some therapeutic interventions that are routine in ordinary, everyday critical care must be considered optional in mass critical care, either because they are not immediately lifesaving, or because they are so resource intensive. The adult task force identified renal replacement therapy and enteral nutrition as optional for mass critical care. Local leaders may decide to attempt optional therapies in a public health emergency if resources are available. However, mass critical care goals to maximize population outcomes require that optional therapy must not limit evidence-based care of patients who would benefit from simpler interventions.
Since infants and children have a large surface-area-to-mass ratio, they are far more prone to the deleterious effects of environmental hypothermia than adult patients. Thus, it is imperative to avoid environmental cold stress in burn patients and infants and small children. As such, radiant warmers already available at a hospital may need to be supplemented by ancillary equipment to warm entire rooms serving multiple patients.
While many of the recent and comprehensive plans for mass adult casualties can be directly adapted to surge capacity plans to care for critically ill infants and children, comprehensive planning (Table 5) also requires collaboration within healthcare systems and within regions to meet the peculiar and essential equipment and supply needs of pediatric patients.
The Pediatric Emergency Mass Critical Care Task Force thanks the American Academy of Pediatrics and its Disaster Preparedness Advisory Council for their review and contributions to this issue.
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Keywords:©2011The Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies
children; critical illness; disaster; emergency mass critical care; equipment; mass casualties; pandemics; pediatric; supplies