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PICU in the MICU

Initial waves of the COVID-19 pandemic have largely spared children. With the advent of vaccination in many older age groups and the spread of the highly contagious Delta variant, however, children now represent a growing percentage of COVID-19 cases. PICU capacity is far less than that of adult ICUs. Adult ICUs may need to support pediatric care, much as PICUs provided adult care earlier in the pandemic. Critically ill children selected for care in adult settings should be at least 12 years of age and ideally have conditions common in children and adults alike (eg, community-acquired sepsis, trauma). Children with complex, pediatric-specific disorders are best served in PICUs and are not recommended for transfer. The goal of such transfers is to maintain critical capacity for those children in greatest need of the PICU’s unique abilities, therefore preserving systems of care for all children.

Earlier waves of the COVID-19 pandemic have largely spared children; however, an increased risk for severe illness and death has been described in older adolescents, children with obesity, children with developmental disorders, and Black or Hispanic children, similar to that seen in adults. 1 In the first waves of the pandemic, PICUs in many centers modified their admission criteria to assume care of younger adult patients, decompressing adult ICUs and increasing critical care capacity in their regions. 2 In general, COVID-19 in children has been less severe, with less direct impact on pediatric hospital care than in adult settings. 3 In the summer of 2021, this situation changed. After a period of marked decline in COVID-19 incidence with the availability of vaccines, case rates and hospitalizations again rose sharply in many countries, in part because of the emergence of the highly contagious Delta (B.1.617.1) variant. 4 Because vaccines against SARS-CoV-2 remain highly protective against hospitalization and death, this wave has become a pandemic of the unvaccinated. 5 The current vaccines available in the United States are presently authorized for use in people $ 12 years of age; however, vaccine uptake in eligible children remains incomplete, similar to older groups. 6 This leaves children among ABBREVIATIONS: CCI = chronic critical illness; CCP = critical clinical prioritization; CF = cystic fibrosis; CSC = crisis standards of care; ECMO = extracorporeal membrane oxygenation; HSCT = hematopoietic stem cell transplantation; PCCI = pediatric chronic critical illness; SOT = solid organ transplantation those most susceptible to SARS-CoV-2 infection, and PICU capacity has been confronted by marked increases in demand because of COVID-19 and other reemergent infections (eg, respiratory syncytial virus) in many regions. 7 Surge Continuum Framework to Increase PICU Capacity With dwindling ICU capacity, much attention has been given to crisis standards of care (CSC) protocols, in the press and by government agencies. As a critical care community, we must harness much energy to plan and build ICU surge capacity in a community effort to avoid the need for CSC protocols. This must also be true for PICU surge capacity, given the potentially catastrophic moral distress we could encounter in a pediatric CSC scenario.
We propose using the established surge continuum framework to use understood nomenclature to build PICU surge capacity as subsequently described. In 2014, the American College of Chest Physicians (CHEST) 8 and the Task Force for Mass Critical Care recommended that health systems use a previously described framework for critical care surge responses. In this framework, responses to a disaster are divided into conventional (where existing hospital resources are sufficient to meet increased demand), contingency (where additional resources, such as staff and space, are needed but the normal standard of care can be met), and crisis (where severe resource limitations force a modification in standards of care). 8,9 More recently, a transition between contingency and crisis has been proposed, a critical clinical prioritization (CCP) level. CCP reflects a stage before a formal crisis where physicians modify their use of resources in ways that are broadly within the standard of care but vary in important ways. For example, patients requiring continuous renal replacement therapy might receive treatment for 12 h/d instead of 24 h/d, allowing two patients to receive therapy instead of one. This CCP level, while still falling within the boundaries of contingency care, is an indicator that a system is approaching crisis. 10 Of the approximately 84,000 staffed nonneonatal ICU beds in nonfederal hospitals in the United States, only 5,115 (6.0%) are pediatric beds 11 ; these also have less surge capacity and tend to be consolidated in densely populated cities. 12 Additionally, there are fewer health care workers skilled at caring for younger children, and pediatric supplies are not available at all hospitals. The surge continuum framework previously cited can increase PICU capacity during emergencies in a standard fashion, based on regional requirements. Similar principles were used by PICUs to increase adult ICU capacity for the adult COVID-19 ICU surge during the first COVID-19 wave in the United States. 13 In 2011, the Pediatric Emergency Mass Critical Care Task Force 14 emphasized that all hospitals, pediatric or otherwise, must maintain a baseline capacity to care for children in the event of a mass casualty event or similar emergency. Using the concepts of conventional, contingency, CCP, and crisis responses, we propose in Table 1 specific age cutoffs for pediatric care in adult ICUs. The goal of this structure is to avoid crisis by increasing capacity during the contingency and CCP phases.

Lessons Learned From Pediatric Intensivists Caring for Adult Patients
In March 2020, COVID-19 first swept through the United States and led to unanticipated surges in adult ICUs; pediatric physicians, nurses, and others were recruited to help increase system capacity. Although not specifically trained in adult medicine, the underlying concepts in respiratory failure and sepsis management are similar. In many centers, adult hospitalists assisted during rounds and managed patients' chronic needs, whereas pediatric professionals focused on the acute management of respiratory failure, shock, and other ICU concepts. Invasive procedures could be performed by practitioners with training in both adult and pediatric care (eg, pediatric surgeons, anesthesiologists). These concepts can be similarly applied to adult ICUs should PICUs be confronted with a pediatric surge. We suggest these lessons be applied, but in reverse, to provide pediatric care in adult units. A proposed staffing model for pediatric patients in an adult ICU is presented in Figure 1.

Patient Tracking
A clear system for tracking children displaced to adult facilities is vital. This was critically underlined after Hurricane Katrina in 2005, when < 25% of > 2,400 displaced children were reunited with their parents 2 weeks after the disaster. 15 Keys to implementation of such a system include the following: (1) advanced planning for communication throughout the regional system of care; (2) inclusion of schools, daycare centers, law enforcement, EDs, and transport services in planning and tracking; and (3) predesignation of appropriate transport teams and admission criteria for children in adult ICUs vs PICUs. 16 It is important that the date, time, location, and manner of entry into the system are documented. Protocols designed for photographic tracking within the system and regional distribution of pediatric patients should be nested within local and regional surge planning. 17 For additional guidance, the American Academy of Pediatrics reunification toolkit is a useful resource (  These younger children should be weighed and medications administered according to standard medication references. When a scale is not available or in emergency situations, length-based systems can rapidly estimate weights and therefore appropriate medication doses and equipment sizing. Standardized tape-based methods that correlate body length with weight are sufficiently accurate for the calculation of drug doses. 18,19 Length-based resuscitation aids can also reduce the number of nonautomatic decisions (and hence cognitive load) when taking care of a smaller child, improving both dose accuracy and time to intervention. Pediatric code sheets are amenable to length-based dosing and can be especially helpful in environments less familiar with pediatric resuscitation, when the cognitive load for physicians can be high.
Pharmacists must be closely involved with any pediatric dosing plan in a nonpediatric hospital. Medication supplies should be evaluated by the pharmacy for availability of standard pediatric concentrations of common medications for the age group receiving care, including vaccinations. Special attention should be paid to medication differences in smaller children (ie, < 12 years of age and/or 40 kg) including the following: (1) maximum total dose limits (in addition to the dose/kg), (2) age-specific weight-based dosing (especially in infancy and related to glomerular filtration rate, such as with vancomycin), (3) obesity (especially with sedation and volume of distribution, and ventilator management and ideal body weight), (4) failure to thrive (as is common in pediatric chronic critical illness [PCCI]), (5) medication pump library access to weight-based dosing, and (6) online order entry capability for pediatricappropriate doses.
Indications for noninvasive and invasive ventilation and for central venous catheterization in adolescents are similar to those in young adults. As expected, this population tends to be resilient with better outcomes than older adults, assuming no significant comorbidities. Although infants and younger children are more likely to present in cold shock (eg, vasoconstriction with delayed capillary refill, tachycardia, and poor contractility), necessitating epinephrine for fluidrefractory hypotension, adolescents are more likely to present in distributive shock with bounding pulses and flash capillary refill. For them, initial vasopressor therapy with norepinephrine is reasonable. 20 Of note, the definition of hypotension for children is derived from the formula of systolic BP < 70 þ 2 (age in years) until it reaches 90 mm Hg. Therefore, a 12-year-old patient would have the same threshold for systolic hypotension as an adult (systolic BP < 90 mm Hg). 21 Mechanical ventilation should be managed the same as for a young adult, using ARDSnet criteria to calculate predicted body weight to optimize tidal volumes at 4 to 8 mL/kg. 22 Common PICU Diagnoses The admitting diagnosis and comorbidities of the ill child in the PICU will play a major role in the decision to transfer to an adult ICU. Certain diseases are common in both adults and older children, and an adult intensivist will have little difficulty managing these conditions (and may have considerable experience in these disorders). A previous comparison of 12-year-old to 19-year-old patients admitted to adult vs PICUs in the United Kingdom found similar mortality rates in both groups. 23 Conversely, other diseases are largely unique to pediatrics, and children suffering from these often have complex needs requiring extensive expertise that will be lacking in adult ICUs. A summary of relevant diagnoses is found on Table 3.

Community-Acquired Sepsis
Community-acquired sepsis includes the following: pneumonia, bacterial meningitis, or pyelonephritis.

Cystic Fibrosis
With improvements in cystic fibrosis (CF) care, patients commonly survive to adulthood; therefore, many adult intensivists are familiar with CF management in the ICU. Additionally, many US-trained intensivists are also trained in pulmonary medicine and have additional expertise in CF; however, this may not be true in other countries.

Sickle Cell Disease
Many adult intensivists have considerable experience with sickle cell disease given the increased lifespan, especially given the limited differences between adult and adolescent management in the acute setting.

History of Solid Organ Transplantation
In solid organ transplantation (SOT) recipients, the underlying immunosuppression and complications are similar in older children and younger adults. Institutional expertise may be more important than age; a 15-year-old patient with a history of kidney transplantation might be better served in an adult SOT center than in a pediatric center without SOT experience.

Hematopoietic Stem Cell Transplantation
Similarly, hematopoietic stem cell transplantation (HSCT) in adolescents may share similar underlying disease processes (eg, acute lymphoblastic leukemia) as young adults. ICU readmission is common among critically ill pediatric HSCT recipients, with 29% of children with HSCT admitted to PICUs in one series requiring three or more such admissions. 24 In these cases, patients may acquire features of PCCI (subsequently described) and therefore be best served in a pediatric center.

Diabetes Mellitus
The management of diabetic ketoacidosis and other hyperglycemic crises are not significantly different in .

Diabetes mellitus .
Adolescent trauma (if the adult ICU is part of a trauma center) and poisonings .
Multisystem inflammatory syndrome in children .
chestjournal.org adolescents, and both adult and pediatric intensivists are likely to have wide experience.

Adolescent Trauma, Poisonings, and Other Ingestions
Assuming affected children are in good health prior to their injury or poisoning, they can be managed safely with appropriate specialty consultation.

Critical Illness Because of COVID-19 Pneumonia
Therapy for severe pediatric illness because of COVID-19 pneumonia may include supportive care, glucocorticoids, thromboprophylaxis, antiviral medications (remdesivir), and immunomodulators (eg, IL-6 antagonists, Janus kinase inhibitors). It is fair to assume that a typical adult intensivist today is intimately familiar with COVID-19 management.

Multisystem Inflammatory Syndrome in Children
This postviral inflammatory complication of COVID-19 occurs in younger adults but is more common in children. As a new and relatively rare disorder, it is likely that few intensivists (adult or pediatric) have extensive experience outside of large referral centers. In both cases, reference to institutional multisystem inflammatory syndrome in children guidelines (Table 2) and rheumatology consultation will be useful.

Pediatric Illnesses Preferably Managed in a PICU
There are conditions for which continued PICU care is necessary, even when they occur in older children. These include the following: Congenital heart disease in patients under the routine care of a pediatric cardiologist (eg, single ventricle physiology, repaired defects with significant residual disease). Adult intensivists and cardiologists rarely have significant experience in these disorders. Pediatric malignancies, particularly those treated on a Children's Oncology Group protocol, with infrequent exceptions (eg, some cases of acute lymphoblastic leukemia that normally could receive care in either the adult or pediatric settings). Chronic kidney disease and end-stage kidney disease in children under the routine care of a pediatric nephrologist. As with heart disease, these differ in their etiology, metabolic effects, and management from adult disease. PCCI. A common population receiving care in PICUs are children with PCCI, defined as children who remain hospitalized in a PICU for > 14 consecutive days or have a history of prolonged ICU stays and two or more acute care of ICU admissions within 12 months, plus either ongoing dependence on one or more forms of technology to sustain vital functions (eg, ventilator, gastrostomy) and/or persistent multisystem disease. 25 These children may include survivors of serious neonatal illnesses, children with significant developmental delay, children with chromosomal or rare genetic disorders, survivors of complex polytrauma, or members of other groups with particularly debilitating clinical courses.
Chronic critical illness (CCI) is described in adults, and patients with CCI have been estimated as reflecting 7.6% of all adult ICU admissions. 26 Adults with CCI have a high mortality rate, with > 60% dying in-hospital and > 50% of survivors dying within 6 months of discharge. 27 Children with PCCI have a more variable risk of death and may comprise $ 40% of patients admitted to PICUs. 28 Although acute issues seen in these children may be within an adult intensivist's scope of practice, the complex multidisciplinary nature of care for these children and their families requires an institutional infrastructure that will almost certainly be absent in an adult center.

Informed Consent and Pediatric Decision-making
Critically ill children who are unable to communicate are treated as a similar adult patient would be: emergency care is rendered first and not delayed for contacting the parent or guardian, as mandated by the Emergency Medical Treatment and Active Labor Act. In the ICU, most care that is delivered is necessary for the survival and well-being of the child. In this context, the goals of care are established by the care team along with parents or guardians. It is not legally necessary to solicit specific assent from minor children; however, they should be fully informed of the treatment plan and decision-making process, if able. If there is discord between the care team and parents, ethics consultation should be obtained. If there are concerns that harm or neglect has occurred to the child, the local Child Protective Services organization should be contacted. 29 Visitation, Family Support, and Staff Wellness Visitation needs for the parents and guardians of children may differ from those of families of adult patients. Although family visitation is important for all patients, these rights are often limited in the setting of COVID-19. We suggest that two adult visitors, typically parents or guardians, be authorized daily visitation for a hospitalized child in an adult ICU, to the greatest extent possible while maintaining staff and patient safety. 30 Critical care physicians in an adult ICU may be accustomed to dying adults, but it is probable that the prospect of a dying child would be uniquely distressing; family visitation, along with appropriate team-based and individual psychosocial support, may be important for patient and physician well-being alike.
Palliative and End-of-Life Care Discussions surrounding pediatric end-of-life care, as in adults, primarily involves the immediate family, but specifically the parents or guardians. There are excellent publications that provide guidance on palliative care in children that go beyond the scope of this article; readers should refer to these publications for further insights. 31,32 As is typical in the delivery of critical care, end-of-life issues should involve a multidisciplinary team and include social workers, chaplains, and palliative care experts when available.

Brain Death Evaluations
The current pediatric brain death guidelines were last updated in 2011. 33 The pediatric brain death evaluation is similar to adults. Unlike in adults, a second confirmatory examination is a criterion for brain death and is to be performed after a 12-h period of observation in children > 30 days to 18 years of age. There are technical considerations in the assessment of suspected brain death in children with COVID-19, including risks of aerosolization during apnea testing and transmission concerns if cerebral perfusion testing in the nuclear medicine suite is to be performed. In all cases, appropriate precautions including personal protective equipment are necessary. 34

Subspecialty Consultation
Adult intensivists know that patient care in the ICU requires more expertise than the specialty of critical care medicine alone. Like with adults, pediatric subspecialty services are essential to the care of critically ill children.
Although consultation practices vary between institutions, the need for pediatric subspecialist input will be increased when cared for in an adult ICU. Contingency planning should incorporate subspecialist availability both in-person and through telemedicine services. Unlike adult subspecialists, pediatric medical and surgical subspecialists are even fewer in number and more likely to be concentrated at dedicated referral centers. 35,36 Establishing a mechanism for formal collaboration with such a center will be useful for the adult ICU providing pediatric care.
PICUs will have varying levels of capability; these were previously described as level 1 or level 2 PICUs, but guideline statements have defined PICUs as quaternary/ specialized (eg, dedicated units for transplant or congenital heart disease), tertiary (capable of providing ECMO and other advanced general therapies), and community (capable of core ICU interventions such as invasive mechanical ventilation and care for septic shock, for example, but potentially lacking other therapies such as ECMO). 37 These capabilities are summarized in Table 4. Contingency plans should make every effort to meet the established standard of care for PICU services, which include subspecialty services as subsequently listed.
Specific consultative considerations include the following: Anesthesia. Anesthesia services for patients outside of infants and toddlers are often routinely covered by nonpediatric specialists, except for patients with In general, patients > 12 years of age with an endotracheal tube size of $ 6.0 should allow passage of an adult-sized bronchoscope. Lavage volumes in pediatric patients are usually smaller than those used in adults. Bronchoscopy in younger patients requires the assistance of pediatric pulmonologists and intensivists, at a minimum. Neurology. ICU-related neurologic issues require pediatric-specific consultation because seizure presentation and therapy differ significantly in younger patients. Similarly, the etiology and therapy for neurovascular diseases also differ from adults and will benefit from a pediatric neurologist. Nephrology. Although ICU-acquired acute kidney injury can likely be managed as with adult patients, electrolyte and fluid management will likely require a pediatric nephrologist, especially as related to renal replacement therapies. Dialysis catheter insertion in patients # 12 years of age will need specialist input.

Telecritical Care
Telemedicine services are a valuable tool for consultation with pediatric intensivists and consulting subspecialists. Peer-to-peer consultation or routine participation in daily rounding may be appropriate based on individual site factors, but a standard approach should be defined prior to initiating contingency care. Modern telemedicine technology allows for in-depth assessment and interactive abilities by the remote physician but may be too time consuming during surge operations without an established system and support team. Pediatric telehealth services have grown in recent years, particularly in response to the COVID-19 pandemic, in part because of the efforts of the Supporting Pediatric Research on Outcomes and Utilization of Telehealth (SPROUT) program, an initiative of the American Academy of Pediatrics. 38 Most of the impact of the program has been in outpatient care, and as mentioned previously, pediatric subspecialists (including intensivists) are few in number. Care will be necessary to identify mechanisms for appropriate telehealth referrals, including hospital credentialing and licensure issues. Lower fidelity approaches (eg, telephone calls) may be used as an alternative to synchronous consultation, but appropriate security and privacy considerations must be addressed.

Summary
There are more similarities than differences between the critical care of adults and older children. Much as PICUs provided care for adult patients early in the COVID-19 pandemic, adult ICUs should be able to support pediatric care for well-selected patients. Clear admission criteria, appropriate protocols, and the availability of regular pediatric consultation can permit adult centers to help preserve effective care for all children.