Nonpulmonary organ failure and outcome in children treated with high-frequency oscillatory ventilation

High-Frequency Oscillatory Ventilation Use and Severe Pediatric ARDS in the Pediatric Hematopoietic Cell Transplant Recipient

INTRODUCTION

The effectiveness of high-frequency oscillatory ventilation (HFOV) in the pediatric hematopoietic cell transplant patient has not been established. We sought to identify current practice patterns of HFOV, investigate parameters during HFOV and their association with mortality, and compare the use of HFOV to conventional mechanical ventilation in severe pediatric ARDS.

METHODS

This is a retrospective analysis of a multi-center database of pediatric and young adult allogeneic hematopoietic cell transplant subjects requiring invasive mechanical ventilation for critical illness from 2009 through 2014. Twelve United States pediatric centers contributed data. Continuous variables were compared using a Wilcoxon rank-sum test or a Kruskal-Wallis analysis. For categorical variables, univariate analysis with logistic regression was performed.

RESULTS

The database contains 222 patients, of which 85 subjects were managed with HFOV. Of this HFOV cohort, the overall pediatric ICU survival was 23.5% (n = 20). HFOV survivors were transitioned to HFOV at a lower oxygenation index than nonsurvivors (25.6, interquartile range 21.1-36.8, vs 37.2, interquartile range 26.5-52.2, P = .046). Survivors were transitioned to HFOV earlier in the course of mechanical ventilation, (day 0 vs day 2, P = .002). No subject survived who was transitioned to HFOV after 1 week of invasive mechanical ventilation. We compared subjects with severe pediatric ARDS treated only with conventional mechanical ventilation versus early HFOV (within 2 d of invasive mechanical ventilation) versus late HFOV. There was a trend toward difference in survival (conventional mechanical ventilation 24%, early HFOV 30%, and late HFOV 9%, P = .08).

CONCLUSIONS

In this large database of pediatric allogeneic hematopoietic cell transplant subjects who had acute respiratory failure requiring invasive mechanical ventilation for critical illness with severe pediatric ARDS, early use of HFOV was associated with improved survival compared to late implementation of HFOV, and the subjects had outcomes similar to those treated only with conventional mechanical ventilation.

High-frequency oscillatory ventilation for acute respiratory distress syndrome

OBJECTIVE

To evaluate the effectiveness of HFOV in pediatric patients with acute respiratory distress syndrome.

METHODS

In this retrospective study, we reviewed all 20 pediatric patients, who were consecutively ventilated with HFOV in the pediatric intensive care unit of a tertiary medical center, from January 2006 to February 2007.

RESULTS

A total of 20 patients were enrolled. The median age of the subjects was 70 (3-168) months; 10 were male. All patients received conventional ventilation before HFOV. After initiation of HFOV, there was an immediate and sustained increase in PaO(2)/FiO(2) ratio. The PaO(2)/FiO(2) ratio was elevated and OI was decreased significantly after 10-20 minutes and maintained for at least 48 hours (p= 0.03, both). Thirteen of the 20 patients were successfully weaned. No significant change in the mean arterial pressure and heart rate was noted after HFOV. Overall survival rate was 65%. Of 20 patients, 11 patients suffered from extrapulmonary ARDS (ARDSexp) and 9 from pulmonary ARDS (ARDSp). When HFOV was initiated, there was significant increase in PaO(2)/FiO(2) and decrease in OI in ARDSexp compared to ARDSp (p= 0.03, both). Also mortality rate was significantly lower in patients with ARDSexp (9% vs.66%), (p= 0.01).

CONCLUSION

In our study, HFOV was effective in oxygenation and seems to be safe for pediatric ARDS patients. HFOV affected ARDSp and ARDSexp paediatric patients differently. However prospective, randomized controlled trials are needed to identify its benefits over conventional modes of mechanical ventilation.

High-frequency oscillatory ventilation in infants and children

The goal of mechanical ventilation in patients with acute lung injury is to support gas exchange and mitigate ventilator-associated lung injury. High-frequency oscillatory ventilation relies on the generation of a constant distending pressure, small tidal volumes and rapid respiratory rates with the intent to recruit atelectatic lung, reduce peak inflating pressures and limit volutrauma. The utilization of high-frequency oscillatory ventilation has dramatically increased in neonatal and pediatric intensive care units. As there is an overlap between the intensive care unit and the operating room, anesthesiologists must be familiar with recent advances in the care of infants and children with acute respiratory failure. High-frequency oscillatory ventilation has been used successfully to manage patients with severe respiratory failure who have failed conventional mechanical ventilation. When initiated early, high-frequency oscillatory ventilation has been shown to improve oxygenation and reduce acute and chronic lung injury in neonates, infants and children. Further trials are necessary to better delineate the benefits and risks of this therapy in various patient populations.

High-frequency oscillatory ventilation in pediatric patients with acute respiratory failure

OBJECTIVE

To evaluate the effectiveness of high-frequency oscillatory ventilation (HFOV) in pediatric patients with acute respiratory failure, failing conventional ventilation.

DESIGN

A prospective, clinical study.

SETTING

Tertiary care pediatric intensive care unit.

PATIENTS

Twenty pediatric patients (ages 12 days to 5 yrs) with acute respiratory failure (pneumonia, 14; sepsis with acute respiratory distress syndrome, 3; pulmonary edema as a complication of upper airway obstruction, 2; salicylate intoxication with acute respiratory distress syndrome, 1), failing conventional ventilation (median alveolar-arterial oxygen difference [P(A-a)O2] 578 [489-624] torr, median oxygenation index 26 [21-32].

INTERVENTIONS

HFOV was instituted after a median length of conventional ventilation of 15.5 (3.3-43.5) hrs.

MEASUREMENTS AND MAIN RESULTS

Ventilator settings, arterial blood gases, oxygenation index, and P(A-a)O2 were recorded before HFOV (0 hrs) and at predetermined intervals during HFOV and compared using the one-way Friedman rank-sum procedure and a two-tailed Wilcoxon matched-pairs test. Initiation of HFOV caused a significant decrease in FiO2 at 1 hr that continued to 24 hrs (p <or= .04). In all patients, target ventilation was achieved, and 19 had improved oxygenation. After 1 hr, PaCO2 significantly decreased (p = .002) and remained within the target range thereafter. There were significant decreases in P(A-a)O2 and oxygenation index at 1 and 4 hrs, respectively, that were sustained up to 12 hrs (p <or= .04). No significant complications associated with HFOV were detected. Fifteen patients (75%) survived to hospital discharge. Only one patient died from respiratory failure.

CONCLUSIONS

In pediatric patients with acute respiratory failure, failing conventional ventilation, HFOV improves gas exchange in a rapid and sustained fashion. However, randomized controlled trials are needed to identify its benefits over conventional modes of mechanical ventilation.

Oxygenation index predicts outcome in children with acute hypoxemic respiratory failure

To define outcome and time dependence of predictors of outcome in pediatric acute hypoxemic respiratory failure, 131 patients (age range, 1 month to 18 years) were prospectively followed. Parametric models were used to describe time-related events, and competing risks analysis was performed for mortality estimates. Multiple logistic analysis was applied to describe time-related predictors of ventilation time and mortality. Overall mortality was 27%. Peak oxygenation index (OI) measured at any time point (p < 0.001, 91% reliability in bootstrapping, after inverse transformation) and Pediatric Risk of Mortality, or PRISM, score within the first 12 hours of mechanical ventilation (p < 0.001, 63% reliability in bootstrapping, after square transformation) were identified as independent predictors of mortality. Peak OI, younger age, and need for renal replacement therapy were significantly associated with a longer time to extubation. Although OI was less reliable as outcome predictor within the first 12 hours of intubation, it still predicted duration of mechanical ventilation. No clear-cut threshold of OI was identified that could accurately predict mortality. Survival was characterized by a peak rate of extubations at approximately 1 week, with a more gradual decline thereafter, whereas death appeared as a constant risk over time, which exceeded chances of survival at approximately 4 weeks. Severity of oxygenation failure at any point in time during acute hypoxemic respiratory failure correlates with duration of mechanical ventilation and mortality. This is best reflected by the OI, which shows a direct correlation to outcome in a time-independent manner.

High-frequency oscillatory ventilation in paediatric patients with acute respiratory distress syndrome--early rescue use

In order to determine the response to high-frequency oscillatory ventilation (HFOV), used as an "early rescue" therapy, in a cohort of paediatric patients with acute respiratory distress syndrome (ARDS), a prospective clinical study was performed in a tertiary care paediatric intensive care unit. Ten consecutive patients, aged 12 days to 5 years with ARDS and hypoxaemic respiratory failure on conventional ventilation (CV), using a lung protective strategy, were managed with HFOV early in the course of the disease process (median length of CV 4 h). Arterial blood gases, oxygenation index (OI), alveolar-arterial oxygen difference (P(A-a)O2) and PaO2/FIO2 ratio were prospectively recorded prior to HFOV (0 h) and at predetermined intervals throughout the course of the HFOV protocol. There was a significant improvement in PaCO2 4 h after institution of HFOV (P = 0.012). A significant and sustained increase (P < 0.001) in PaO2/FIO2 ratio and a significant and sustained decrease (P < 0.001) in OI and P(A-a)O2 were demonstrated during the HFOV trial. These improvements were achieved 4 h after initiating HFOV (P < 0.05). Eight patients survived. There were no deaths from respiratory failure.

CONCLUSION

In paediatric patients with acute respiratory distress syndrome and hypoxaemic respiratory failure on conventional ventilation, using a lung protective strategy, high-frequency oscillatory ventilation used as an "early rescue" therapy, improves gas exchange in a rapid and sustained fashion and provides a good outcome. Use of this therapy should probably be considered early in the course of the disease process.

Cumulative influence of organ dysfunctions and septic state on mortality of critically ill children

The interaction between sepsis and multiple organ dysfunction syndrome is poorly defined in children. We analyzed by Cox regression models the cumulative influence of organ dysfunctions, using the pediatric logistic organ dysfunction (PELOD) score, and septic state (systemic inflammatory response syndrome or sepsis, severe sepsis, and septic shock) on mortality of critically ill children. We included 593 children (mortality rate: 8.6%) from three pediatric intensive care units; 514 patients had at least a systemic inflammatory response syndrome and 269 had two or more organ dysfunctions. Hazard ratio of death significantly increased with the severity of organ dysfunction, as estimated by the PELOD score, and the worst diagnostic category of septic state. Each increase of one unit in the PELOD score multiplied the hazard ratio by 1.096 (p < 0.0001); hazard ratio of diagnostic category was 9.039 (p = 0.031) for systemic inflammatory response syndrome or sepsis, 18.797 (p = 0.007) for severe sepsis and 32.572 (p < 0.001) for septic shock. Cumulative hazard ratio of death = (hazard ratio of PELOD score) x (hazard ratio of diagnostic category). We conclude that there is a cumulative accrual of the risk of death both with an increasing severity of organ dysfunction and an increasing severity of the diagnostic category of septic state.

Survival of severe ARDS with five-organ system failure following burns and inhalation injury in a 15-year-old patient

OBJECTIVE

To show the effectiveness of an integrated therapeutical approach in a severe case of acute respiratory distress syndrome (ARDS) following burns, inhalation injury with therapy-refractory oxygenation under maximized ventilatory settings, and an overall complicated clinical course.

PATIENT AND METHODS

Case report of a patient with severe inhalation injury and burns in an intensive care unit setting, undergoing cardiopulmonary resuscitation (CPR), nitric oxide (NO)-inhalation, surfactant-, kinetic-, and urodilatin-therapy.

CASE REPORT

A 15-year-old male presented with deep dermal and full thickness thermal injuries involving 25% of his total body surface area. Shortly after presentation, the patient developed therapy-refractory respiratory failure, cardiac arrest, and subsequently suffered five-organ system failure (lung, heart, gastrointestinal, liver, kidney), in addition to burn injury, and ischemia related cerebral lesions. The patient was successfully treated with cardiac resuscitation, extra corporeal membrane oxygenation (ECMO), NO, kinetic therapy, surfactant, urodilatin, and other standard intensive care regimens. Three months post-trauma the patient was discharged home, nearly fully recovered.

CONCLUSIONS

In a patient with severe ARDS, oxygenation failure under maximized ventilatory settings, and subsequent five-organ system failure, an integrated therapeutical approach comprising ECMO, NO, kinetic therapy, surfactant, and urodilatin did cross-bridge respiratory and vital functions, enabling overall survival.

Pediatric Extracorporeal Life Support After High Frequency Ventilation: Predictors of Survival

Previous studies of extracorporeal life support in pediatric patients have identified variables associated with survival. However, none of these studies focused on extracorporeal life support after failure of high frequency ventilation (HFV). In the present study, we determined variables associated with survival for pediatric respiratory failure patients who received HFV prior to extracorporeal life support, using data reported to the Extracorporeal Life Support Organization Registry from 1992 to 1998. Patients with neonatal diagnoses, immune compromising conditions, or congenital cardiac defects were excluded. The 243 patients who met inclusion criteria had a 58% survival rate (95% CI 48-66%). The mean age was 22 +/- 39 months. Mean duration of mechanical ventilation prior to extracorporeal life support was 6.6 +/- 5.8 days. Venoarterial extracorporeal life support was used in 72% of the patients; venovenous in 28%. The survival rate for the subset of patients with an oxygenation index greater than 42 cm H2O/torr on HFV (n = 122) was not significantly different from the overall sample. We determined that lower mean airway pressure, lower pressure amplitude, decreased oxygenation index, increased PaO2, and increased oxygen saturation on HFV were associated with increased survival in patients who were subsequently treated with extracorporeal life support.

Current concepts in adult respiratory distress syndrome in children

Acute respiratory distress syndrome (ARDS) is an acute form of severe alveolar-capillary injury that evolves after a direct or indirect lung insult. It begins as noncardiogenic pulmonary edema and develops into a neutrophilic alveolitis, and, later, pulmonary fibrosis. Mortality remains high among children with ARDS, particularly when serious underlying conditions co-exist, sepsis occurs, and when there is multi-organ failure. Lung function improves with time among survivors, but pulmonary fibrosis may persist. Advances in the care of children with ARDS include the use of lung-protective ventilator strategies, permissive hypercapnia, inhaled nitric oxide, high-frequency ventilation, and extra-corporeal life support. These approaches reduce ventilator-associated lung injury and may improve survival when used in combination with one another. Interventions that reduce alveolar inflammation, enhance alveolar fluid removal, and reduce pulmonary fibrosis will further improve survival and recovery from ARDS in the future.