The use of high frequency oscillatory ventilation in a pediatric oncology intensive care unit

The effect of high-frequency oscillatory ventilation or airway pressure release ventilation on children with acute respiratory distress syndrome as a rescue therapy

BACKGROUND

To investigate the effects of high-frequency oscillatory ventilation (HFOV) or airway pressure release ventilation (APRV) as a rescue therapy on children with moderate and severe acute respiratory distress syndrome (ARDS).

METHODS

We retrospectively enrolled 47 children with ARDS who were transitioned from synchronized intermittent mandatory ventilation (SIMV) to either HFOV or APRV for 48 h or longer after failure of SIMV. The parameters of demographic data, arterial blood gases, ventilator settings, oxygenation index (OI), and PaO₂/FiO₂ (PF) ratio during the first 48 h of HFOV and APRV were recorded.

RESULTS

There was no significant difference between the HFOV and APRV groups with survival rates of 60% and 72.7%, respectively. Compared to pre-transition, the mean airway pressures at 2 and 48 h after transition were higher in both groups (P<0.01), and the PF ratio at 2 and 48 h in both modes was significantly improved (P<0.001). PF ratio and PaCO₂ have significant differences at 48 h between two groups. The OI at 2 h after transition had no improvement in either group and was substantially lower at 48 h relative to the pre-transition level (P<0.001) in both groups. At 48 h after the transition to both HFOV and APRV, the survivors had lower mean airway pressures, higher PF ratios, and a lower OIs than non-survivors (P<0.01).

CONCLUSIONS

There was no significant difference on the survival rates of HFOV and APRV application as a rescue therapy for ARDS, but improved oxygenation at 48 h reliably discriminated survivors from non-survivors in both groups.

The impact of high frequency oscillatory ventilation on mortality in paediatric acute respiratory distress syndrome

BACKGROUND

High-frequency oscillatory ventilation (HFOV) use was associated with greater mortality in adult acute respiratory distress syndrome (ARDS). Nevertheless, HFOV is still frequently used as rescue therapy in paediatric acute respiratory distress syndrome (PARDS). In view of the limited evidence for HFOV in PARDS and evidence demonstrating harm in adult patients with ARDS, we hypothesized that HFOV use compared to other modes of mechanical ventilation is associated with increased mortality in PARDS.

METHODS

Patients with PARDS from 10 paediatric intensive care units across Asia from 2009 to 2015 were identified. Data on epidemiology and clinical outcomes were collected. Patients on HFOV were compared to patients on other modes of ventilation. The primary outcome was 28-day mortality and secondary outcomes were 28-day ventilator- (VFD) and intensive care unit- (IFD) free days. Genetic matching (GM) method was used to analyse the association between HFOV treatment with the primary outcome. Additionally, we performed a sensitivity analysis, including propensity score (PS) matching, inverse probability of treatment weighting (IPTW) and marginal structural modelling (MSM) to estimate the treatment effect.

RESULTS

A total of 328 patients were included. In the first 7 days of PARDS, 122/328 (37.2%) patients were supported with HFOV. There were significant differences in baseline oxygenation index (OI) between the HFOV and non-HFOV groups (18.8 [12.0, 30.2] vs. 7.7 [5.1, 13.1] respectively; p < 0.001). A total of 118 pairs were matched in the GM method which found a significant association between HFOV with 28-day mortality in PARDS [odds ratio 2.3, 95% confidence interval (CI) 1.3, 4.4, p value 0.01]. VFD was indifferent between the HFOV and non-HFOV group [mean difference - 1.3 (95%CI - 3.4, 0.9); p = 0.29] but IFD was significantly lower in the HFOV group [- 2.5 (95%CI - 4.9, - 0.5); p = 0.03]. From the sensitivity analysis, PS matching, IPTW and MSM all showed consistent direction of HFOV treatment effect in PARDS.

CONCLUSION

The use of HFOV was associated with increased 28-day mortality in PARDS. This study suggests caution but does not eliminate equivocality and a randomized controlled trial is justified to examine the true association.

Severe infections in neutropenic patients

PURPOSE OF REVIEW

Severe infections in neutropenic patients can rapidly progress to septic shock and multiorgan failure with a high associated mortality. In this article we discuss current practice, emerging trends and controversies, including the prophylactic and empiric use of antimicrobial therapy, and advances in cellular and immunotherapy.

RECENT FINDINGS

Neutropenia is no longer a consistent factor predicting poor outcome in haematological patients admitted to the ICU. Severe infections in neutropenic patients are often polymicrobial, and pathogen resistance remains a challenge. Invasive fungal infection is still predictive of poor outcome. There has been a rapid expansion in the diagnostics and treatment modalities available for patients with invasive fungal infection. Use of growth factors, polyvalent immunoglobulin, and cellular therapy appear to be of value in certain groups of patients. There is a move away from the use of noninvasive ventilation and the use of high-flow nasal oxygen therapy is one of a number of novel respiratory support strategies that is yet to be evaluated in this patient population.

SUMMARY

Translation of current advances in antimicrobial, cellular and immunotherapy, and diagnostics to aid clinical management by the bedside is important in reducing morbidity and mortality for neutropenic patients with severe infection.

[Critically ill pediatric hemato-oncology patient: What we do is what we should do?]

OBJECTIVE

Primary objective, to describe the management and monitorization of critically ill pediatric hemato-oncology patient (CIPHO) in the Spanish pediatric intensive care units (PICU). Secondary objective, through a literature review, to identify possible areas of improvement.

MATERIAL AND METHODS

Observational transversal descriptive study. An anonymous web-based survey was sent to 324 Spanish pediatric intensivists from April 2011 to May 2011. None of them were pediatric residents.

RESULTS

The survey was answered by 105 intensivists, 59/105 always agreed their treatment with the oncologist. In case of hemodynamic instability, non-invasive blood pressure monitoring is always done by 85/105 and almost always optimized by intra-arterial measuring (85/105) and central venous pressure (70/105). If respiratory failure the use of non-invasive ventilation (NIPPV) is always (36/105) or frequently (60/105) established prior to conventional mechanical ventilation. To replace or withdraw non-invasive ventilation only 44/96 of the respondents to this question use a clinical protocol. Before the instauration of conventional mechanical ventilation the oncological prognosis is considered by 72/105. In case of acute oliguric renal failure the renal replacement techniques are widely used (74/105). The withdrawal of sustaining life support is frequently discussed (75/103) and agreed with the oncologist (91/103) and caregivers (81/103).

CONCLUSIONS

In our study, despite there is not a defined standard-of-care, the respondents showed similar therapeutics and monitorization choices. The use of NIPPV as first respiratory assistance is extended. Prospective, observational and multicenter studies should be developed to establish the results of this management in this population.

Respiratory Failure in Children With Hemato-oncological Diseases Admitted to the PICU: A Single-center Experience

Respiratory failure (RF) is a main cause of pediatric intensive care unit (PICU) admission in children with hemato-oncological diseases. We present a retrospective chart review of children admitted to our PICU because of RF (January 2006 to December 2010). The aims of this study are the following: (1) to describe the demographical and clinical characteristics and respiratory management of these children; and (2) to identify the factors associated with mechanical ventilation (MV) and mortality. A total of 69 patients, encompassing 88 episodes, were included (55/88 cases were hypoxemic RF). The first respiratory support at PICU admission was, in decreasing order of frequency, high-flow oxygen nasal cannula (HFNC; 50/88), noninvasive ventilation (NIV; 13/88), and oxygen nasal cannula (16/88). MV was necessary in 47/88 episodes, 38/47 after another respiratory support. In 18/28 children with initial NIV, MV was required later. MV was associated with O-PRISM score, NIV requirement, suspected respiratory infection, and days of PICU treatment. Patients without MV showed an increased survival rate (P=0.001). In summary, the hypoxemic RF was the main cause of PICU admission, and HFNC or NIV was almost always the first respiratory support. The use of MV was associated with a higher mortality rate. The utility of precocious HFNC or NIV should be investigated in larger clinical studies.

Improved oxygenation 24 hours after transition to airway pressure release ventilation or high-frequency oscillatory ventilation accurately discriminates survival in immunocompromised pediatric patients with acute respiratory distress syndrome*

OBJECTIVES

Children with an immunocompromised condition and requiring invasive mechanical ventilation have high risk of death. Such patients are commonly transitioned to rescue modes of nonconventional ventilation, including airway pressure release ventilation and high-frequency oscillatory ventilation, for acute respiratory distress syndrome refractory to conventional ventilation. Our aim was to describe our experience with airway pressure release ventilation and high-frequency oscillatory ventilation in children with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation and to identify factors associated with survival.

DESIGN

Retrospective cohort study.

SETTING

Tertiary care, university-affiliated PICU.

PATIENTS

Sixty pediatric patients with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographic data, ventilator settings, arterial blood gases, oxygenation index, and PaO(2)/FIO(2) were recorded before transition to either mode of nonconventional ventilation and at predetermined intervals after transition for up to 5 days. Mortality in the entire cohort was 63% and did not differ between patients transitioned to airway pressure release ventilation and high-frequency oscillatory ventilation. For both airway pressure release ventilation and high-frequency oscillatory ventilation, improvements in oxygenation index and PaO(2)/FIO(2) at 24 hours expressed as a fraction of pretransition values (oxygenation index(24)/oxygenation index(pre) and PaO(2)/FIO(224)/PaO(2)/FIO(2pre)) reliably discriminated nonsurvivors from survivors, with receiver operating characteristic areas under the curves between 0.89 and 0.95 (p for all curves < 0.001). Sensitivity-specificity analysis suggested that less than 15% reduction in oxygenation index (90% sensitive, 75% specific) or less than 90% increase in PaO(2)/FIO(2) (80% sensitive, 94% specific) 24 hours after transition to airway pressure release ventilation were the optimal cutoffs to identify nonsurvivors. The comparable values 24 hours after transition to high-frequency oscillatory ventilation were less than 5% reduction in oxygenation index (100% sensitive, 83% specific) or less than 80% increase in PaO(2)/FIO(2) (91% sensitive, 89% specific) to identify nonsurvivors.

CONCLUSIONS

In this single-center retrospective study of pediatric patients with an immunocompromised condition and acute respiratory distress syndrome failing conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation, improved oxygenation at 24 hours expressed as PaO(2)/FIO(224)/PaO(2)/FIO(2pre) or oxygenation index(24)/oxygenation indexpre reliably discriminates nonsurvivors from survivors. These findings should be prospectively verified.

High-frequency oscillatory ventilation in children with acute respiratory distress syndrome: experience of a pediatric intensive care unit

OBJECTIVE

To describe the effects of high-frequency oscillatory ventilation (HFOV) as a rescue ventilatory support in pediatric patients with acute respiratory distress syndrome (ARDS).

METHODS

Twenty-five children (1 month < age < 17 years) admitted to a university hospital pediatric intensive care unit (ICU) with ARDS and submitted to HFOV for a minimum of 48 hours after failure of conventional mechanical ventilation were assessed.

RESULTS

Twenty eight days after the onset of ARDS, the mortality rate was 52% (13/25). Over the course of 48 hours, the use of HFOV reduced the oxygenation index [38 (31-50) vs. 17 (10-27)] and increased the ratio of partial arterial pressure O2 and fraction of inspired O2 [65 [44-80) vs. 152 (106-213)]. Arterial CO2 partial pressure [54 (45-74) vs. 48 (39-58) mmHg] remained unchanged. The mean airway pressure ranged between 23 and 29 cmH2O. HFOV did not compromise hemodynamics, and a reduction in heart rate was observed (141±32 vs. 119±22 beats/min), whereas mean arterial pressure (66±20 vs. 71±17 mmHg) and inotropic score [44 (17-130) vs. 20 (16-75)] remained stable during this period. No survivors were dependent on oxygen.

CONCLUSION

HFOV improves oxygenation in pediatric patients with ARDS and severe hypoxemia refractory to conventional ventilatory support.

Stem cell transplantation and lung dysfunction

PURPOSE OF REVIEW

To identify factors that impact the incidence and severity of lung dysfunction after haematopoietic stem cell transplantation (HSCT) for preventive and therapeutic purposes.

RECENT FINDINGS

Respiratory failure from lung dysfunction after HSCT is a serious and often fatal transplant-related complication, but recent data reveal decreasing incidence and improving outcome over time. Idiopathic pneumonia syndrome (IPS) and bronchiolitis obliterans are now recognized as part of a spectrum of post-HSCT lung diseases involving both aspects of innate and adaptive immune responses, but may differ in the main lung structure affected: alveolar versus airway epithelium. There exists a strong association between acute graft-versus-host disease (GVHD) and IPS, and bronchiolitis obliterans is pathognomonic of chronic GVHD. Experimental models of IPS and bronchiolitis obliterans have proven useful to test strategies designed to limit lung injury including the effects of allogeneity, chemoradiotherapy and stem cell therapy. Recent advances in critical care practices, early diagnosis and utilizing ARDS Network ventilatory and conservative fluid management recommendations have also contributed to better outcome from lung dysfunction after HSCT.

SUMMARY

Understanding the factors that contribute to post-HSCT lung injury should lead to safer transplant practices that will allow the broader use of HSCT for sicker children with comorbidities.