Exchange transfusion to reverse severe pertussis-induced cardiogenic shock

Exchange transfusion in the management of critical pertussis in young infants: a case series

BACKGROUND AND OBJECTIVES

It is proposed that severe leucocytosis mainly contributes to pulmonary hypertension by blocking pulmonary capillaries and restricting blood flow. Exchange transfusion (ET) in pertussis has been demonstrated as a safe and useful technique for depleting the leucocyte mass. We aim to discuss four cases of pertussis-induced respiratory distress and the effectiveness of ET in such a setting.

MATERIALS AND METHODS

We conducted a retrospective case series at the Infectious Disease Department of Children's Hospital 2 in Ho Chi Minh City, Vietnam, and included four pertussis patients that were confirmed by PCR tests on respiratory secretions, presented with severe leucocytosis and respiratory distress and required mechanical ventilation.

RESULTS

Among the included patients, three underwent a double volume ET for leucodepletion, two of whom were discharged after the procedure with proper vitals and laboratory test results. On the other hand, one patient died despite ET, performed late in the course of the disease. Exchange transfusion was not performed in the last patient who died as well.

CONCLUSION

Early ET may be a useful and rapid life-saving treatment in children with critical pertussis and severe leucocytosis before cardiopulmonary complications appear.

Risk factors associated with death in infants <120 days old with severe pertussis: a case-control study

Background and purpose

Pertussis is a serious infectious disease in young infants, and severe cases frequently cause death. Our study explored risk factors for death from severe pertussis.

Method

A case-control study of infants with severe pertussis admitted to the paediatric intensive care unit (PICU) in the Children’s Hospital of Chongqing Medical University, China, from January 1, 2013, to June 30, 2019, was conducted. Pertussis was confirmed by clinical features and laboratory examinations. Severe pertussis was defined as patients with pertussis resulting in PICU admission or death. To understand the risk factors for death, we compared fatal and nonfatal cases of severe pertussis in infants aged < 120 days by collecting clinical and laboratory data.

Results

The participants included 63 infants < 120 days of age with severe pertussis. Fifteen fatal cases were confirmed and compared with 44 nonfatal severe pertussis cases, Four patients with termination of treatment were excluded. In the univariate analysis, the risk factors associated with death included apnoea (P = 0.001), leukocytosis (white blood cell (WBC) count≥30 × 10⁹/L (P = 0.001) or ≥ 50 × 10⁹/L (P = 0)), highest lymphocyte count (P = 0), pulmonary hypertension (P = 0.001), and length of PICU stay (P = 0.003). The multivariate analysis revealed that apnoea (OR 23.722, 95%CI 2.796–201.26, P = 0.004), leukocytosis (OR 63.708, 95%CI 3.574–1135.674, P = 0.005) and pulmonary hypertension (OR 26.109, 95%CI 1.800–378.809, P = 0.017) were significantly associated with death.

Conclusion

Leukocytosis and pulmonary hypertension exhibited the greatest associations with death in infants with severe pertussis admitted to the PICU. Vaccination is still the most effective protection method against pertussis.

Clinical Profile of Critical Pertussis in Children at a Pediatric Intensive Care Unit in Northern India

Objective

To delineate the clinical profile, complications, intensive care needs, and predictors of mortality in children with critical pertussis.

Methods

Retrospective analysis of case records of children in the pediatric intensive care unit of a tertiary-care hospital, with a diagnosis of critical pertussis over 3 years. Diagnostic criteria included CDC case definition and confirmation by polymerase chain reaction (PCR), when available. Survivors and nonsurvivors were compared to identify predictors of mortality.

Results

36 records were analysed, most cases were infants (31, 86.1%). 10 (27.7%) were (below 6 weeks of age). In the rest, 16 (61.5%) were partially immunized or unimmunized against pertussis. Rapid breathing (88.9%), paroxysmal cough (86.1%) and apnea (41.7%) were common presenting complaints. Hypoxemia (97.2%), hyperleukocytosis (61.1%) and encephalopathy (52.8%) were common complications. Intensive care needs were mechanical ventilation in 11 (30.6%), vasoactive support in 7 (19.4%) and exchange transfusion in 3 (8.3%). Female gender, apnea, hyperleukocytosis, encephalopathy, need for vasoactive support, and mechanical ventilation predicted mortality.

Conclusion

Pertussis demands attention due to its varied presentation, increased complications and higher mortality.

Fatal malignant pertussis with hyperleukocytosis in a Chinese infant: A case report and literature review

RATIONALE

Pertussis has re-emerged on a global scale and is an ongoing public health problem, even in countries with high rates of vaccination. Hyperleukocytosis [white blood cell (WBC) count >100 × 10/L] is a rare complication that strongly predicts mortality in cases of severe pertussis.

PATIENT CONCERNS

We report a case of severe pertussis in an infant who initially presented with persistent cyanotic cough, tachypnea, and grunting. The infant's condition deteriorated rapidly, and she was transferred to the pediatric intensive care unit (PICU) during her third hour of hospitalization. On the third hospital day, her WBC count had increased to 101.85 × 10/L with a lymphocyte count of 36.76 × 10/L, and her hemoglobin level had fallen to 6.9 g/dL. Bone marrow examination found no evidence of tumor cells. Her initial echocardiogram showed no abnormal findings; however, a subsequent echocardiogram 10 days later revealed pulmonary hypertension.

DIAGNOSES

The patient was diagnosed with severe pneumonia, which was confirmed to be pertussis based on a persistent cough in the infant's mother and the polymerase chain reaction and culture of the infant's nasopharyngeal secretions being positive for Bordetella pertussis.

INTERVENTIONS

The infant was treated with supportive care, early macrolide antibiotics, and broad-spectrum antibiotics before being transferred to the PICU for further management, including continuous venovenous hemodiafiltration.

OUTCOMES

Unfortunately, the infant died as a result of pulmonary hypertension and multiorgan failure.

LESSONS

Exchange transfusion should be considered in all infants who present with severe pertussis with hyperleukocytosis. This guideline is supported by the findings of a comprehensive literature review, which is included in this article, as well as newly published criteria for exchange transfusion therapy. Finally, we hope that adults in China will be vaccinated against B. pertussis in order to prevent the infection of infants within their households.

Extracorporeal Membrane Oxygenation for Pertussis: Predictors of Outcome Including Pulmonary Hypertension and Leukodepletion

OBJECTIVE

The recent increase of pertussis cases worldwide has generated questions regarding the utility of extracorporeal membrane oxygenation for children with pertussis. We aimed to evaluate factors associated with extracorporeal membrane oxygenation outcome.

DESIGN

The study was designed in two parts: a retrospective analysis of the Extracorporeal Life Support Organization Registry to identify factors independently linked to outcome, and an expanded dataset from individual institutions to examine the association of WBC count, pulmonary hypertension, and leukodepletion with survival.

SETTING

Extracorporeal Life Support Organization Registry database from 2002 though 2015, and contributions from 19 international centers.

PATIENTS

Two hundred infants from the Extracorporeal Life Support Organization Registry and expanded data on 73 children.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 200 infants who received extracorporeal membrane oxygenation for pertussis, only 56 survived (28%). In a multivariable logistic regression analysis, the following variables were independently associated with increased chance of survival: older age (odds ratio, 1.43 [1.03-1.98]; p = 0.034), higher PaO2/FIO2 ratio (odds ratio, 1.10 [1.03-1.17]; p = 0.003), and longer intubation time prior to the initiation of extracorporeal membrane oxygenation (odds ratio, 2.10 [1.37-3.22]; p = 0.001). The use of vasoactive medications (odds ratio, 0.33 [0.11-0.99]; p = 0.047), and renal neurologic or infectious complications (odds ratio, 0.21 [0.08-0.56]; p = 0.002) were associated with increased mortality. In the expanded dataset (n =73), leukodepletion was independently associated with increased chance of survival (odds ratio, 3.36 [1.13-11.68]; p = 0.03) while the presence of pulmonary hypertension was adverse (odds ratio, 0.06 [0.01-0.55]; p = 0.01).

CONCLUSIONS

The survival rate for infants with pertussis who received extracorporeal membrane oxygenation support remains poor. Younger age, lower PaO2/FIO2 ratio, vasoactive use, pulmonary hypertension, and a rapidly progressive course were associated with increased mortality. Our results suggest that pre-extracorporeal membrane oxygenation leukodepletion may provide a survival advantage.

The use of cytapheresis in the treatment of infectious diseases

Cytapheresis (removal of cellular blood components) has been employed for treatment of infectious diseases since the 1960s. Techniques have included thrombocytapheresis (buffy coat apheresis) for loiasis, erythrocytapheresis for malaria and babesiosis, and leukocytapheresis for pertussis-associated lymphocytosis. Published data on these applications is largely limited to case level data and small observational studies; as such, recommendations for or against the use of cytapheresis in the treatment of infections have been extrapolated from these limited (and at times flawed) data sets. Consequently, utilization of cytapheresis in many instances is not uniform between institutions, and typically occurs at the discretion of treating medical teams. This review revisits the existing literature on the use of cytapheresis in the treatment of four infections (loasis, malaria, babesiosis, and pertussis) and examines the rationale underlying current treatment recommendations concerning its use.

Leukemoid Reaction in Infant Pertussis: Is There a Place for Hydroxyurea? A Case Report

A 73-days old infant of 34 weeks' gestation was hospitalized with a co-infection of respiratory syncytial virus (RSV) and Bordetella pertussis (BP). She required invasive ventilation for 9 days in the context of malignant pertussis with persistent hypoxemia and hypercapnia secondary to a leukemoid reaction. Despite an increase of white blood cell (WBC) count up to 70 G/L and ensuing pulmonary hypertension, no hemodynamic compromise occurred. Without clear indication for leukapheresis nor exchange transfusion, an off-label treatment with hydroxyurea was given for 5 days with gradual decrease of WBC count, without any complication and hospital discharge on day 29. To our knowledge, no effective therapy for malignant pertussis has been described in the literature and complications are frequent with leukoreduction procedures. We discuss an alternative to invasive procedures in young infants to fulfill the need to decrease rapidly leukocyte counts in a leukemoid reaction associated with Bordetella pertussis infection. To our knowledge, hydroxyurea has never been used in malignant pertussis but is a well-known medication for oncologic and hematologic diseases such as acute myeloid leukemia or sickle cell anemia. Its effects in this setting are not well understood but the positive outcome in our patient supports the need for further studies.

Bordetella pertussis

Pertussis is a highly infectious vaccine-preventable cough illness that continues to be a significant source of morbidity and mortality around the world. The majority of human illness is caused by Bordetella pertussis, and some is caused by Bordetella parapertussis. Bordetella is a Gram-negative, pleomorphic, aerobic coccobacillus. In the past several years, even countries with high immunization rates in early childhood have experienced rises in pertussis cases. Reasons for the resurgence of reported pertussis may include molecular changes in the organism and increased awareness and diagnostic capabilities, as well as lessened vaccine efficacy and waning immunity. The most morbidity and mortality with pertussis infection is seen in infants too young to benefit from immunization. Severe infection requiring hospitalization, including in an intensive care setting, is mostly seen in those under 3 months of age. As a result, research and public health actions have been aimed at better understanding and reducing the spread of Bordetella pertussis. Studies comparing the cost benefit of cocooning strategies versus immunization of pregnant women have been favorable towards immunizing pregnant women. This strategy is expected to prevent a larger number of pertussis cases, hospitalizations, and deaths in infants <1 year old while also being cost-effective. Studies have demonstrated that the source of infection in infants usually is a family member. Efforts to immunize children and adults, in particular pregnant women, need to remain strong.

Identifying Children at Risk of Malignant Bordetella pertussis Infection

OBJECTIVE

To identify factors associated with malignant pertussis.

DESIGN

A retrospective case notes review from January 2003 to August 2013. Area under the receiver-operator characteristic curve was used to determine how well vital sign and white cell characteristics within 48 hours of hospital presentation identified children with malignant pertussis.

SETTING

The national children's hospital in Auckland, New Zealand.

PATIENTS

One hundred fifty-two children with pertussis.

MEASUREMENTS AND MAIN RESULTS

There were 152 children with confirmed pertussis identified, including 11 children with malignant pertussis. The area under the receiver-operator characteristic curve was 0.88 (95% CI, 0.78-0.97) for maximum heart rate. The optimal cut-point was 180 beats/min, which predicted malignant pertussis with a sensitivity of 73% and a specificity of 91%. The area under the receiver-operator characteristic curve was 0.92 (95% CI, 0.81-1.0) for absolute neutrophil count, 0.85 (95% CI, 0.71-0.99) for total WBC count, 0.80 (95% CI, 0.63-0.96) for neutrophil-to-lymphocyte ratio, and 0.77 (95% CI, 0.58-0.92) for absolute lymphocyte count. All children with malignant pertussis had one or more of heart rate greater than 180 beats/min, total WBC count greater than 25 × 10/L, and neutrophil-to-lymphocyte ratio greater than 1.0 with an area under the receiver-operator characteristic curve of 0.96 (95% CI, 0.91-1.0) for a multivariate model that included these three variables.

CONCLUSIONS

Clinical predictors of malignant pertussis are identifiable within 48 hours of hospital presentation. Early recognition of children at risk of malignant pertussis may facilitate early referral to a PICU for advanced life support and selection for trials of investigational therapies.

Pertussis: Microbiology, Disease, Treatment, and Prevention

Pertussis is a severe respiratory infection caused by Bordetella pertussis, and in 2008, pertussis was associated with an estimated 16 million cases and 195,000 deaths globally. Sizeable outbreaks of pertussis have been reported over the past 5 years, and disease reemergence has been the focus of international attention to develop a deeper understanding of pathogen virulence and genetic evolution of B. pertussis strains. During the past 20 years, the scientific community has recognized pertussis among adults as well as infants and children. Increased recognition that older children and adolescents are at risk for disease and may transmit B. pertussis to younger siblings has underscored the need to better understand the role of innate, humoral, and cell-mediated immunity, including the role of waning immunity. Although recognition of adult pertussis has increased in tandem with a better understanding of B. pertussis pathogenesis, pertussis in neonates and adults can manifest with atypical clinical presentations. Such disease patterns make pertussis recognition difficult and lead to delays in treatment. Ongoing research using newer tools for molecular analysis holds promise for improved understanding of pertussis epidemiology, bacterial pathogenesis, bioinformatics, and immunology. Together, these advances provide a foundation for the development of new-generation diagnostics, therapeutics, and vaccines.

Protecting Newborns Against Pertussis: Treatment and Prevention Strategies

Pertussis is a potentially severe respiratory disease, which affects all age groups from young infants to older adults and is responsible for an estimated 195,000 deaths occurred globally in 2008. Active research is ongoing to better understand the pathogenesis, immunology, and diagnosis of pertussis. For diagnosis, molecular assays (e.g., polymerase chain reaction) for detection of Bordetella pertussis have become more widely available and support improved outbreak detection. In children, pertussis vaccines have been incorporated into routine immunization schedules and deployed for pertussis outbreak control. Lower levels of vaccine coverage are now being observed in communities where vaccine hesitancy is rising. Additionally, recognition that newborn babies are at risk of pertussis in the USA and UK has led to recommendations to immunize pregnant women. Among adolescents and older adults in the USA, Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular pertussis (Tdap) Vaccines are recommended, but substantial individual- and system-level barriers exist that will make achieving national Healthy People 2020 targets for immunization challenging. Current antimicrobial regimens for pertussis are focused on reducing the severity of disease, reducing rates of sequelae, and minimizing transmission of infection to susceptible individuals. Continued surveillance for pertussis will be important to identify opportunities for reducing young infants' exposure and reducing the impact of outbreaks among school-aged children. Laboratory-based surveillance for newly emerging strains of B. pertussis will be important to identify strains that may evade protection elicited by currently available vaccines. Efforts to develop new-generation pertussis vaccines should be considered now in anticipation of vaccine development programs, which may require ten or more years to deliver a licensed vaccine.

[Malignant pertussis and exchange transfusion]

CASE REPORT

Malignant pertussis is a critical clinical state associated with fatal outcome in 70% of cases. The severity criteria are a lung infection with pulmonary hypertension and hyperleukocytosis usually above 50 G/L. We report the case of a 2.5-month-old girl hospitalized with critical pertussis in a pediatric intensive care unit. She had acute respiratory distress syndrome with pulmonary hypertension complicated by a bacterial secondary infection with Enterobacter cloacae managed by high-frequency oscillatory ventilation associated with pulmonary vasodilatation therapy. In the absence of clinical improvement and before considering extracorporeal life support, exchange transfusion was performed at day 9 to reduce hyperleukocytosis at 70 G/L. Exchange transfusion was successfully performed with a reduction of leukocytes to under 40 G/L followed by steady improvement of pulmonary function. Weaning from mechanical ventilation and discharge took place at day 23 and 38, respectively.

COMMENTS

Exchange transfusion should be considered in infants suffering from malignant pertussis with extreme leukocytosis before hemodynamic failure to improve the survival prognosis.

Severe pertussis and hyperleukocytosis: is it time to change for exchange?

BACKGROUND

Pertussis is an important cause of infant death worldwide and continues to be a public health concern even in countries with high vaccination coverage. Severe (critical) pertussis with hyperleukocytosis is a severe form of the disease with up to 80% mortality rate. Attempts have been reported to reduce the white blood cell burden by exchange transfusion (ET) with conflicting conclusions.

CASE REPORT

We report a case of critical pertussis in a neonate who was treated with ET, in view of a comprehensive literature review.

RESULTS

The patient was discharged without any sequelae.

CONCLUSION

ET should be considered in all infants suffering from critical pertussis and hyperleukocytosis, even in secondary care community hospitals.

Exchange blood transfusion in the management of severe pertussis in young infants

We analyzed data from 10 young infants who received exchange blood transfusions for management of severe pertussis. Our data are insufficient to address efficacy of the procedure, but our data, as well as previous reports in the literature, indicate that if the procedure is to be successful, it should be done before organ failure has occurred and immediately if shock/hypotension occur.

Characteristics of Severe Bordetella pertussis Infection Among Infants ≤90 Days of Age Admitted to Pediatric Intensive Care Units - Southern California, September 2009-June 2011

BACKGROUND

Bordetella pertussis infection can cause severe illness and death among young infants.

METHODS

We collected demographic and clinical information from the medical records of infants who were ≤90 days of age and hospitalized for pertussis in 5 Southern California pediatric intensive care units (PICUs) from September 1, 2009 to June 30, 2011. Infants who died or were diagnosed with pulmonary hypertension were considered to have more severe pertussis.

RESULTS

Thirty-one infants were admitted to a participating PICU. Eight infants had more severe infections, 6 infants had pulmonary hypertension, and 4 infants died. The 8 infants with more severe infections had white blood cell counts that exceeded 30 000, heart rates that exceeded 170, and respiratory rates that exceeded 70 more rapidly after cough onset than the 23 infants with less severe illness.

CONCLUSIONS

Identifying higher-risk infants earlier might allow for more rapid implementation of interventions.

Leukoreduction in patients with severe pertussis with hyperleukocytosis

When pertussis is associated with hyperleukocytosis, mortality approaches to 80%. Immature leukocytes have been identified in pulmonary arterioles, small arteries and venules. Techniques aimed at reducing leukocyte mass might improve the prognosis of these patients. We report our experience with 3 patients in whom a leukoreduction was performed in the context of severe pertussis and hyperleukocytosis.

Hyperleukocytosis in a premature infant with intrauterine herpes simplex encephalitis

Herpes encephalitis is a rare but devastating infection in premature infants. We report a 29 week gestation infant with severe intrauterine cutaneous and central nervous system herpes accompanied by hyperleukocytosis. Leukemoid reactions are not uncommon in this population, but the association of herpes encephalitis and a leukemoid reaction or hyperleukocytosis has not been reported previously.

Clinical and laboratory features of pertussis in infants at the onset of a California epidemic

We report clinical characteristics and outcome of infants <3 months of age hospitalized with pertussis compared with viral respiratory infection (respiratory syncytial virus and influenza). Patients with pertussis more often were afebrile, had more visits before admission, and had longer hospital stays. Household coughing contacts were common.

Pertussis: should we improve intensive care management or vaccination strategies?

Bordetella pertussis, responsible for one of the oldest vaccine-preventable diseases in children, has resurged in North America, Europe, Latin America and many countries around the world. Despite new recommended vaccination strategies for adolescents, pregnant women and adults, mortality is still significant in developing and developed countries. For the critical care management of the infant with pertussis, strategies include conventional ventilation, high-frequency oscillatory ventilation, extracorporeal membrane oxygenation, inhaled nitric oxygen, exchange transfusion, plasmapheresis and, more recently, leukodepletion. The paper under evaluation describes the experience of UK investigators in the management of pertussis with rapid leukodepletion for infants with extreme leukocytosis. Using this strategy, a rapid fall in the number of leukocytes was observed in these patients. Their results suggest that rapid leukodepletion should be considered in severely ill infants with pertussis and severe leukocytosis.

Early blood exchange transfusion in malignant pertussis: a case report

OBJECTIVE

To report early blood exchange transfusion in malignant pertussis and a favorable clinical outcome.

SETTING

A pediatric intensive care unit in a tertiary hospital in Geneva, Switzerland.

DESIGN

A descriptive case report.

PATIENT

An 8-wk-old girl was diagnosed with malignant pertussis (extreme leukocytosis, seizures, pneumonia, and secondary severe hypoxic respiratory failure associated with pulmonary hypertension). After administration of a one-volume blood exchange transfusion, a rapid decrease in white blood cell count (from 119,000/mm(3) to 36,500/mm(3)) was observed and followed by clinical improvement and favorable outcome despite the initial presence of all described risk factors associated with a high mortality.

CONCLUSION

The use of exchange blood transfusion early in the course of the disease might help to prevent a fatal outcome of malignant pertussis.

Impact of rapid leukodepletion on the outcome of severe clinical pertussis in young infants

OBJECTIVES

Bordetella pertussis is a common, underrecognized, and vaccine-preventable cause of critical illness with a high mortality in infants worldwide. Patients with severe cases present with extreme leukocytosis and develop refractory hypoxemia and pulmonary hypertension that is unresponsive to maximal intensive care. This may reflect a hyperviscosity syndrome from the raised white blood cell (WBC) count. Case reports suggest improved outcomes with exchange transfusion to reduce the WBC count. Our objective was to quantify possible benefits of aggressive leukodepletion.

METHODS

We, as a regional PICU and extracorporeal membrane oxygenation referral center, adopted a strategy of aggressive leukodepletion in January 2005. The impact of this strategy on crude and case mix-adjusted survival of all infants who were critically ill with B pertussis were compared with control subjects from January 2001 to December 2004 and Extracorporeal Life Support Organisation registry data.

RESULTS

Nineteen infants (7 [37%] boys) received intensive care for B pertussis from 2001 to 2009. Admission WBC counts were equivalent in 2 time periods: 2001-2004 (mean: 52,000/μL) and 2005-2009 (mean: 75,000/μL). In 2001-2004, 5 (55%) of 9 patients survived the ICU. Between 2005 and 2009, 9 (90%) of 10 patients survived. When case-mix adjustment for age, WBC count, and extracorporeal membrane oxygenation referral were considered, the 2001-2004 predicted survival (4.4 [49%] of 9.0) was equivalent to the observed mortality (4.0 [44%] of 9.0). Between 2005 and 2009, observed mortality (1.0 [10%] of 10.0) was significantly better than predicted (4.7 [47%] of 10.0).

CONCLUSIONS

Leukodepletion should be considered in critically ill infants with B pertussis and leukocytosis.

Pathology and pathogenesis of fatal Bordetella pertussis infection in infants

BACKGROUND

Each year, Bordetella pertussis infection causes an estimated 294,000 deaths worldwide, primarily among young, nonvaccinated children. Approximately 90% of all deaths due to pertussis in the Unites States occur in young infants. These children often develop intractable pulmonary hypertension; however, the pathophysiologic mechanism responsible for this complication has not been well characterized, and there have been no detailed descriptions of the pathology of this disease since the 1940s.

METHODS

Respiratory tissue samples obtained at autopsy from 15 infants aged <or=4 months who had polymerase chain reaction- or culture-confirmed B. pertussis pneumonia were evaluated by multiple histochemical stains, immunohistochemical evaluation, and electron microscopic examination.

RESULTS

The pulmonary histopathologic examination of the samples revealed a descending infection dominated by necrotizing bronchiolitis, intra-alveolar hemorrhage, and fibrinous edema. All samples had marked leukocytosis, and most showed luminal aggregates of abundant leukocytes in small pulmonary arteries, veins, and lymphatics. A novel immunohistochemical stain for B. pertussis revealed abundant extracellular bordetellae in cilia of the trachea, bronchi, and bronchioles, as well as intracellular bacteria and antigens in alveolar macrophages and ciliated epithelium.

CONCLUSIONS

Pertussis should be suspected in any infant death associated with marked leukocytosis, bronchopneumonia, or refractory pulmonary hypertension, particularly in children aged <or=4 months. The pathologic findings identified in the respiratory tracts of these children, in addition to recognized physiologic responses of the infant lung to hypoxia, suggest that B. pertussis pneumonia triggers a cascade of events that includes acute pulmonary vasoconstriction and pertussis toxin-mediated increases in circulating leukocyte mass. These responses ultimately compromise pulmonary blood flow, exacerbate hypoxemia, and create a vicious cycle of refractory pulmonary hypertension.

Multiple organ system extracorporeal support in critically ill children

Multiple organ system extracorporeal support effectively supports brain, heart, lung, liver, kidney, coagulation, red blood cell, and immune cell function in the sickest infants and children who have multiple organ system failure. These therapies have optimum benefit if: (1) the underlying disease is reversible; (2) the therapies are performed expertly and are monitored to prevent and minimize systemic hemolysis; and (3) the therapies are provided in a goal-directed manner. These therapies represent a significant advance in pediatric critical care medicine. This article provides a framework for this multidisciplinary team approach for implementing these therapies.