Sabrina M. Heidemann

High-frequency oscillatory ventilation in pediatric respiratory failure: A multicenter experience

ObjectiveThe use of high-frequency oscillatory ventilation (HFOV) has increased dramatically in the management of respiratory failure in pediatric patients. We surveyed ten pediatric centers that frequently use high-frequency oscillation to describe current clinical practice and to examine factors related to improved outcomes. DesignRetrospective, observational questionnaire study. SettingTen tertiary care pediatric intensive care units. PatientsTwo hundred ninety patients managed with HFOV between January 1997 and June 1998. InterventionsNone. Measurements and Main ResultsPatients were classified according to presence or absence of preexisting lung disease, symptomatic respiratory syncytial virus infection, or presence of cyanotic heart disease or residual right-to-left intracardiac shunt. In addition, patients for whom HFOV acutely failed were analyzed separately. Those patients with preexisting lung disease were significantly smaller, had a significantly higher incidence of pulmonary infection as the triggering etiology, and had a significantly greater duration of conventional ventilation before institution of HFOV compared with patients without preexisting lung disease. Stepwise logistic regression was used to predict mortality and the occurrence of chronic lung disease in survivors. In patients without preexisting lung disease, the model predicted a 70% probability of death when the oxygenation index (OI) after 24 hrs was 28 in the immunocompromised patients and 64 in the patients without immunocompromise. In the immunocompromised patients, the model predicted a 90% probability of death when the OI after 24 hrs was 58. In survivors without preexisting lung disease, the model predicted a 70% probability of developing chronic lung disease when the OI at 24 hrs was 31 in the patients with sepsis syndrome and 50 in the patients without sepsis syndrome. In the patients with sepsis syndrome, the model predicted a 90% probability of developing chronic lung disease when the OI at 24 hrs was 45. ConclusionsGiven the number of centers involved and the size of the database, we feel that our results broadly reflect current practice in the use of HFOV in pediatric patients. These results may help in deciding which patients are most likely to benefit from aggressive intervention by using extracorporeal techniques and may help identify high-risk populations appropriate for prospective study of innovative modes of supporting gas exchange (e.g., partial liquid breathing or intratracheal pulmonary ventilation).

Does prematurity alter the course of respiratory syncytial virus infection

We compared previously healthy prematurely born infants with full-term infants hospitalized with respiratory syncytial virus (RSV) infection to evaluate the role of prematurity on the clinical course of the illness. During a 5-yr period (1984 to 1989), 484 previously healthy patients were admitted to the hospital with RSV infection. No differences were found in the presenting symptoms of respiratory distress, cough, fever or shock, although the premature group was more likely to present with apnea (p < .001). Chest roentgenograms revealed that premature infants had a higher incidence of atelectasis/infiltrate and hyperinflation (p < .05). Premature infants had longer hospital stays as well as a higher Physiologic Stability Index and Therapeutic Intervention Score (p < .001). They were also more likely to receive supplemental oxygen, ICU admission, mechanical ventilation, and nothing by mouth status (p < .001). We conclude that premature birth increases the risk of more severe and prolonged RSV disease.

Predicting outcome in children with severe acute respiratory failure treated with high-frequency ventilation

OBJECTIVES a) To demonstrate the effect of high-frequency ventilation on gas exchange in children with severe acute respiratory failure unresponsive to conventional ventilation; b) to identify patients at high risk of death early after institution of high-frequency ventilation. SETTING Tertiary care pediatric intensive care unit in a university hospital. DESIGN A cross-sectional, observational study with factorial design. PATIENTS Thirty-one patients with severe acute respiratory failure defined as a Pao2/F1o2 of < 150 torr (< 20 kPa) with a positive end-expiratory pressure of > or = 8 cm H2O and/or Paco2 of > 60 torr (> 8 kPa) with an arterial pH < 7.25. INTERVENTIONS Patients received either high-frequency oscillation or jet ventilation if respiratory failure was unresponsive to conventional ventilation and if the underlying disease process was deemed reversible. MEASUREMENTS AND MAIN RESULTS Thirty-one children were managed with high-frequency ventilation, 11 children with jet and 20 children with oscillator. Arterial blood gases and level of ventilatory support were recorded before and at 6, 24, 48, 72, and 96 hrs after institution of high-frequency ventilation. There was an improvement in an arterial pH, Paco2, Pao2, and Pao2/FID2 6 hrs after institution of high-frequency ventilation (p < .01). This improvement, along with decreased need for oxygen, was sustained through the subsequent course. Twenty-three (74%) of 31 children treated with high-frequency ventilation survived. Survivors showed an increase in an arterial pH, Pao2, Pao2/FIO2, and a decrease in Paco2 within 6 hrs, whereas nonsurvivors did not. Oxygenation index was the best predictor of outcome. A combination of an initial oxygenation index of > 20 and failure to decrease the oxygenation index by > 20% by 6 hrs after initiation of high-frequency ventilation predicted death with 88% (7/8) sensitivity and 83% (19/23) specificity, with an odds ratio of 33 (p = .0036, 95% confidence interval 3-365). CONCLUSIONS In patients with potentially reversible underlying diseases resulting in severe acute respiratory failure that is unresponsive to conventional ventilation, high-frequency ventilation improves gas exchange in a rapid and sustained fashion. The magnitude of impaired oxygenation and its improvement after high-frequency ventilation can predict outcome within 6 hrs.

Critical Pertussis Illness in Children: A Multicenter Prospective Cohort Study*

Objective: Pertussis persists in the United States despite high immunization rates. This report characterizes the presentation and acute course of critical pertussis by quantifying demographic data, laboratory findings, clinical complications, and critical care therapies among children requiring admission to the PICU. Design: Prospective cohort study. Setting: Eight PICUs comprising the Eunice Kennedy Shriver National Institute for Child Health and Human Development Collaborative Pediatric Critical Care Research Network and 17 additional PICUs across the United States. Patients: Eligible patients had laboratory confirmation of pertussis infection, were younger than 18 years old, and died in the PICU or were admitted to the PICU for at least 24 hours between June 2008 and August 2011. Interventions: None. Measurements and Main Results: A total of 127 patients were identified. Median age was 49 days, and 105 (83%) patients were less than 3 months old. Fifty-five (43%) patients required mechanical ventilation and 12 patients (9.4%) died during initial hospitalization. Pulmonary hypertension was found in 16 patients (12.5%) and was present in 75% of patients who died, compared with 6% of survivors (p < 0.001). Median WBC was significantly higher in those requiring mechanical ventilation (p < 0.001), those with pulmonary hypertension (p < 0.001), and nonsurvivors (p < 0.001). Age, sex, and immunization status did not differ between survivors and nonsurvivors. Fourteen patients received leukoreduction therapy (exchange transfusion [12], leukopheresis [1], or both [1]). Survival benefit was not apparent. Conclusions: Pulmonary hypertension may be associated with mortality in pertussis critical illness. Elevated WBC is associated with the need for mechanical ventilation, pulmonary hypertension, and mortality risk. Research is indicated to elucidate how pulmonary hypertension, immune responsiveness, and elevated WBC contribute to morbidity and mortality and whether leukoreduction might be efficacious.

Ratio of PICU Versus Ward Cardiopulmonary Resuscitation Events Is Increasing

Objectives:The aim of this study was to evaluate the relative frequency of pediatric in-hospital cardiopulmonary resuscitation events occurring in ICUs compared to general wards. We hypothesized that the proportion of pediatric cardiopulmonary resuscitation provided in ICUs versus general wards has increased over the past decade, and this shift is associated with improved resuscitation outcomes. Design:Prospective and observational study. Setting:Total of 315 hospitals in the American Heart Association’s Get With The Guidelines-Resuscitation database. Patients:Total of 5,870 pediatric cardiopulmonary resuscitation events between January 1, 2000 and September 14, 2010. Cardiopulmonary resuscitation events were defined as external chest compressions longer than 1 minute. Interventions:None. Measurements and Main Results:The primary outcome was proportion of total ICU versus general ward cardiopulmonary resuscitation events over time evaluated by chi-square test for trend. Secondary outcome included return of spontaneous circulation following the cardiopulmonary resuscitation event. Among 5,870 pediatric cardiopulmonary resuscitation events, 5,477 (93.3%) occurred in ICUs compared to 393 (6.7%) in inpatient wards. Over time, significantly more of these cardiopulmonary resuscitation events occurred in the ICU compared to the wards (test for trend: p < 0.01), with a prominent shift noted between 2003 and 2004 (2000–2003: 87–91% vs 2004–2010: 94–96%). In a multivariable model controlling for within center variability and other potential confounders, return of spontaneous circulation increased in 2004–2010 compared with 2000–2003 (relative risk, 1.08; 95% CI, 1.03–1.13). Conclusions:In-hospital pediatric cardiopulmonary resuscitation is much more commonly provided in ICUs than in wards, and the proportion has increased significantly over the past decade, with concomitant increases in return of spontaneous circulation.

Outcome of children with carbon monoxide poisoning treated with normobaric oxygen

OBJECTIVE To evaluate the clinical characteristics and neurologic outcome of children with carbon monoxide poisoning treated with normobaric oxygen therapy. METHODS We reviewed the medical records of all children with a diagnosis of carbon monoxide exposure admitted during a 10-year period. Exposures were categorized as (1) severely toxic, carboxyhemoglobin level >25%; (2) toxic, carboxyhemoglobin level 10.1 to 25%; (3) suspected toxic, carboxyhemoglobin level < or = 10% with acute neurologic manifestations; or (4) nontoxic, carboxyhemoglobin < or = 10% without acute neurologic manifestations. RESULTS One hundred six patients (median age, 3.5 years; range, 0.1-14.9 years) were identified, 37 with severe toxic, 37 with toxic, 13 with suspected toxic, and 19 with nontoxic exposures. The most common presenting signs or symptoms included altered level of consciousness, metabolic acidosis, tachycardia, and hypertension. All patients received normobaric oxygen for 5.5 hours (range, 0.6-44 hours). Carboxyhemoglobin levels decreased to less than 3% in 3.6 hours (range, 0-15.5 hours). Fifteen patients died, three from massive burn injury, eight from hypoxic-ischemic encephalopathy after cardiopulmonary arrest at presentation, and four from late complications of burn injury. Seven survivors did not recover their premorbid neurologic state, four of whom had respiratory arrest when rescued. Two patients had initial neurologic recovery followed by transient deterioration at 4 and 14 days after exposure. One patient developed seizures and was found to have bilateral occipital lobe infarctions 51 days after exposure. CONCLUSION Acute neurologic manifestations after carbon monoxide exposure are common in children. These resolve rapidly with normobaric oxygen, however. Persistent sequelae are primarily related to asphyxia. Delayed neurologic syndromes are uncommon in children treated with normobaric oxygen.

Pressure-controlled ventilation in children with severe status asthmaticus.

Objective The optimum strategy for mechanical ventilation in a child with status asthmaticus is not established. Volume-controlled ventilation continues to be the traditional approach in such children. Pressure-controlled ventilation may be theoretically more advantageous in allowing for more uniform ventilation. We describe our experience with pressure-controlled ventilation in children with severe respiratory failure from status asthmaticus. Design Retrospective review. Setting Pediatric intensive care unit in a university-affiliated children’s hospital. Patients All patients who received mechanical ventilation for status asthmaticus. Interventions Pressure-controlled ventilation was used as the initial ventilatory strategy. The optimum pressure control, rate, and inspiratory and expiratory time were determined based on blood gas values, flow waveform, and exhaled tidal volume. Measurement and Main Results Forty patients were admitted for 51 episodes of severe status asthmaticus requiring mechanical ventilation. Before the institution of pressure-controlled ventilation, median pH and Pco2 were 7.21 (range, 6.65–7.39) and 65 torr (29–264 torr), respectively. Four hours after pressure-controlled ventilation, median pH increased to 7.31 (6.98–7.45, p < .005), and Pco2 decreased to 41 torr (21–118 torr, p < .005). For patients with respiratory acidosis (Pco2 >45 torr) within 1 hr of starting pressure-controlled ventilation, the median length of time until Pco2 decreased to <45 torr was 5 hrs (1–51 hrs). Oxygen saturation was maintained >95% in all patients. Two patients had pneumomediastinum before pressure-controlled ventilation. One patient each developed pneumothorax and subcutaneous emphysema after initiation of pressure-controlled ventilation. All patients survived without any neurologic morbidity. Median duration of mechanical ventilation was 29 hrs (4–107 hrs), intensive care stay was 56 hrs (17–183 hrs), and hospitalization was 5 days (2–20 days). Conclusions Based on this retrospective study, we suggest that pressure-controlled ventilation is an effective ventilatory strategy in severe status asthmaticus in children. Pressure-controlled ventilation represents a therapeutic option in the management of such children.

Association of bleeding and thrombosis with outcome in Extracorporeal Life Support

Objective: Changes in technology and increased reports of successful extracorporeal life support use in patient populations, such as influenza, cardiac arrest, and adults, are leading to expansion of extracorporeal life support. Major limitations to extracorporeal life support expansion remain bleeding and thrombosis. These complications are the most frequent causes of death and morbidity. As a pilot project to provide baseline data for a detailed evaluation of bleeding and thrombosis in the current era, extracorporeal life support patients were analyzed from eight centers in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network. Study Design: Retrospective analysis of patients (< 19 yr) reported to the Extracorporeal Life Support Organization registry from eight Collaborative Pediatric Critical Care Research Network centers between 2005 and 2011. Setting: Tertiary children’s hospitals within the Collaborative Pediatric Critical Care Research Network. Subjects: The study cohort consisted of 2,036 patients (13% with congenital diaphragmatic hernia). Interventions: None. Main Results: In the cohort of patients without congenital diaphragmatic hernia (n = 1,773), bleeding occurred in 38% of patients, whereas thrombosis was noted in 31%. Bleeding and thrombosis were associated with a decreased survival by 40% (relative risk, 0.59; 95% CI, 0.53–0.66) and 33% (odds ratio, 0.67; 95% CI, 0.60–0.74). Longer duration of extracorporeal life support and use of venoarterial cannulation were also associated with increased risk of bleeding and/or thrombotic complications and lower survival. The most common bleeding events included surgical site bleeding (17%; n = 306), cannulation site bleeding (14%; n = 256), and intracranial hemorrhage (11%; n = 192). Common thrombotic events were clots in the circuit (15%; n = 274) and the oxygenator (12%; n = 212) and hemolysis (plasma-free hemoglobin > 50 mg/dL) (10%; n = 177). Among patients with congenital diaphragmatic hernia, bleeding and thrombosis occurred in, respectively, 45% (n = 118) and 60% (n = 159), Bleeding events were associated with reduced survival (relative risk, 0.62; 95% CI, 0.46–0.86) although thrombotic events were not (relative risk, 0.92; 95% CI, 0.67–1.26). Conclusions: Bleeding and thrombosis remain common complications in patients undergoing extracorporeal life support. Further research to reduce or eliminate bleeding and thrombosis is indicated to help improve patient outcome.

Functional Status Scale: New Pediatric Outcome Measure

OBJECTIVE: The goal was to create a functional status outcome measure for large outcome studies that is well defined, quantitative, rapid, reliable, minimally dependent on subjective assessments, and applicable to hospitalized pediatric patients across a wide range of ages and inpatient environments. METHODS: Functional Status Scale (FSS) domains of functioning included mental status, sensory functioning, communication, motor functioning, feeding, and respiratory status, categorized from normal (score = 1) to very severe dysfunction (score = 5). The Adaptive Behavior Assessment System II (ABAS II) established construct validity and calibration within domains. Seven institutions provided PICU patients within 24 hours before or after PICU discharge, high-risk non-PICU patients within 24 hours after admission, and technology-dependent children. Primary care nurses completed the ABAS II. Statistical analyses were performed. RESULTS: A total of 836 children, with a mean FSS score of 10.3 (SD: 4.4), were studied. Eighteen percent had the minimal possible FSS score of 6, 44% had FSS scores of ≥10, 14% had FSS scores of ≥15, and 6% had FSS scores of ≥20. Each FSS domain was associated with mean ABAS II scores (P < .0001). Cells in each domain were collapsed and reweighted, which improved correlations with ABAS II scores (P < .001 for improvements). Discrimination was very good for moderate and severe dysfunction (ABAS II categories) and improved with FSS weighting. Intraclass correlations of original and weighted total FSS scores were 0.95 and 0.94, respectively. CONCLUSIONS: The FSS met our objectives and is well suited for large outcome studies.

Incidence and Outcomes of Cardiopulmonary Resuscitation in PICUs.

Objectives:To determine the incidence of cardiopulmonary resuscitation in PICUs and subsequent outcomes. Design, Setting, and Patients:Multicenter prospective observational study of children younger than 18 years old randomly selected and intensively followed from PICU admission to hospital discharge in the Collaborative Pediatric Critical Care Research Network December 2011 to April 2013. Results:Among 10,078 children enrolled, 139 (1.4%) received cardiopulmonary resuscitation for more than or equal to 1 minute and/or defibrillation. Of these children, 78% attained return of circulation, 45% survived to hospital discharge, and 89% of survivors had favorable neurologic outcomes. The relative incidence of cardiopulmonary resuscitation events was higher for cardiac patients compared with non-cardiac patients (3.4% vs 0.8%, p <0.001), but survival rate to hospital discharge with favorable neurologic outcome was not statistically different (41% vs 39%, respectively). Shorter duration of cardiopulmonary resuscitation was associated with higher survival rates: 66% (29/44) survived to hospital discharge after 1-3 minutes of cardiopulmonary resuscitation versus 28% (9/32) after more than 30 minutes (p < 0.001). Among survivors, 90% (26/29) had a favorable neurologic outcome after 1-3 minutes versus 89% (8/9) after more than 30 minutes of cardiopulmonary resuscitation. Conclusions:These data establish that contemporary PICU cardiopulmonary resuscitation, including long durations of cardiopulmonary resuscitation, results in high rates of survival-to-hospital discharge (45%) and favorable neurologic outcomes among survivors (89%). Rates of survival with favorable neurologic outcomes were similar among cardiac and noncardiac patients. The rigorous prospective, observational study design avoided the limitations of missing data and potential selection biases inherent in registry and administrative data.