Background

A simplified equation for quantification of mechanical energy per breath at the bed side has been proposed in adults, but it is unclear if it is also applicable in a paediatric context.

Objectives

To compare the correlation between the calculated energy per breath (E_{LUNG_C}) normalised to body weight between the simplified equation of motion versus the integral of the area of the dynamic pressure-volume loop (E_{LUNG_M}).

Methods

Using a paediatric lung model with different compliance and resistance settings, we compared the energy delivered to the lungs (E_{LUNG_M}) by measuring the integral of the dynamic pressure-volume area with the energy computed by the simplified equation of motion E_{LUNG_C} = ΔV • (Ppeak__LUNG - ½DP) • 0.098 (mJoules) (E_{LUNG_C :} elastic energy for lung inflation, ΔV variation of tidal volume, Ppeak__LUNG peak pressure in the lung, DP driving pressure). Measurements were made during Pressure (PC) and Volume (VC) controlled ventilation with PEEP 5cmH₂0. Endotracheal tube sizes from 3.0 to 8.0mm were studied.

Results

E_{LUNG_M} was constantly overestimated for a mean of 2.9mJ/kg (mean 5.9±6.3 vs 8.8±6.2 mJ/kg, p<0.05). Bland-Altman analyses showed that computed and measured mechanical energy were significantly different when PC mode was used (beta -0.49 p<0.001) and compliance was above 0.6ml/cmH₂0/kg (beta -0.49 p<0.001). Large ETT sizes showed better accuracy than small (beta 0.01 p=0.11 vs beta -0.03, p=0.002, respectively).

Conclusion

The adult simplified motion of equation is not applicable in the paediatric context. Further clinical studies are needed to verify whether automated calculation of mechanical energy could be applied in mechanically ventilated children.

Background

Weaning children from the ventilator can be performed by gradual reduction of ventilator support or by attempted with alternating periods of complete ventilatory support and graded spontaneous breathing with assistance, also called sprinting.

Objectives

To study the effect of spontaneous breathing on end-expiratory lung volumes (EELV) and center of ventilation (CoV).

Methods

Prospective study in spontaneously breathing, ventilated children aged <5 years who are ventilated >24 hours. CoV and EELV was measured by electrical impedance tomography (EIT). Sixteen electrodes were applied circumferentially around the paediatric chest and measurements were made at a scan rate of 13 Hz for 60 seconds. Patients were studied during pressure regulated ventilation (pressure A/C) or pressure support (PS) ventilation. Secondary, patients were switched to CPAP/PS and PS was reduced up to 6cm H₂O in steps of 2cm H₂O.

Results

22 patients were studied. Median age was 6.4 months (IQR 2.4 – 14.2). No differences in CoV were found when between CPAP/PS (median 49.9%, IQR 45.4 - 51.9) and pressure A/C (49.3%, IQR 45.7 – 51.8), whereas a value <50% indicated that the CoV was located in the anterior half. EELV increased when patients were breathing spontaneously (∆Z -6.63 (IQR -9.75 - -4.69) compared to conventional ventilation ((∆Z -7.46 (IQR -11.37 - -6.22)). Reducing PS shifted the CoV to more the more dependent lung regions, although not statistically significant and clinical relevant. No differences in EELV were found when PS was downgraded.

Conclusion

Spontaneous breathing during weaning from mechanical ventilation did not affect EELV or CoV.

Background

In adult populations, esophageal pressure monitoring is increasingly proving its potential to guide mechanical ventilation. In the paediatric population, the data is limited.

Objectives

To observe and objectify esophageal pressure (Pes) in relationship to illness, biometric data and airway pressure (Paw).

Methods

In mechanically ventilated children, an air-filled balloon catheter is placed in the esophagus. After appropriately positioning, ventilator and esophageal pressures during zero-flow state end-inspiration and end-expiration were recorded. For statistical analysis, the relation between Pes and age, and between Pes and Paw was studied by linear regression analysis. Transpulmonary pressures of patients with and without lung injury and patients with normal and decreased chestwall compliance were compared using unpaired testing.

Results

Fifty-two children (median age of 6.5 months) were studied. N = 41 patients (78.8%) were ventilated for lung injury and 7 patients (13.5%) had a decreased chestwall compliance. Both end-inspiratory and end-expiratory, Pes was not related to age (regression coefficient P values of 0.868 and 0.790, resp.). Only in patients with lung injury, Pes was significantly related to Paw both at end-inspiration and end-expiration (regression coefficient P values 0.038 and 0.002, resp.). In both patients with decreased and normal chestwall compliance, Pes was significantly related to Paw at end-inspiration (regression coefficient P values 0.026 and 0.006, resp.). Transpulmonary plateau pressures are significantly lower in patients with a decreased chestwall compliance compared to patients with a normal chestwall compliance (p=0.038).

Conclusion

Bedside esophageal pressure monitoring is applicable in paediatric clinical setting, though its value remains uncertain due to lack of reference values.

Background

Lung ultrasound (LUS) is becoming an important point-of-care technique in intensive care units. Several semi-quantitative lung ultrasound scores, based on simple LUS signs are available and are used to describe lung aeration and guide respiratory care and interventions. There are currently few data on the relationship between lung mechanics and LUS scores.

Objectives

We aimed to study this relationship to gain an understanding of when a semi-quantitative evaluation of lung aeration may be reliable and useful in clinical practice.

Methods

This is a prospective observational cohort study enrolling NICU-admitted neonates subdivided into three groups:preterm babies with RDS needing intubation and surfactant administration (restrictive pattern group);preterm neonates with developing BPD needing invasive ventilation (mixed pattern group);neonates with no lung disease(control group).LUS was performed by a skilled ultrasonographer and a LUS score was calculated as previously published before surfactant administration, if any.Within 30’ from the LUS examination,respiratory mechanics were evaluated by measuring dynamic compliance(Cdyn) and resistances(Raw).

Results

Sixteen,eleven and eighteen neonates were enrolled in the restrictive,mixed and control groups,respectively.There is a highly significant correlation between LUS and Cdyn for the restrictive pattern group(r= -0.6; p=0.016),but not for either of the other two groups(mixed: r= -0.39; p=0.228; control: r= -0.37; p=0.130).There is no correlation between LUS and Raw for any of the groups(restrictive:r= 0.2; p=0.635; mixed:r= -0.28; p=0.594; control:r= 0.21; p=0.653).

Conclusion

There is an inverse and significant correlation between Cdyn and LUS scores exclusively for patients with a restrictive pattern.The LUS score may be better adapted to evaluate lung mechanics and aeration in restrictive respiratory failure.

Background

Prevention of admission to the Paediatric Intensive Care Unit (PICU) is the aim of any paediatric service. The use of non-invasive respiratory support in the form of HFNC is increasingly popular. Studies indicate that the use of HFNC therapy at the onset of a respiratory illness has the potential to stabilise the child without the need for intubation and ventilation.

Objectives

To establish whether differences exist in children who have received HFNC prior to invasive ventilation compared to those who have not.

Methods

All children admitted to a regional PICU over a 12 month period requiring invasive ventilation were enrolled into the study. Basic demographic data were recorded and the use of HFNC therapy prior to their intubation was noted.

Results

Of the 522 PICU admissions,178 required invasive ventilation. 43/178 (24.2%) of these received HFNC therapy prior to intubation. These children were younger in age - median (IQR) age of 6.4 (1.68-28.33) months vs 47.4 (8.98-130.22) months, p<0.001. Pre-intubation HFNC was associated with a higher number of PICU-free days - median (IQR) of 22.6 (14.40-25.48) days vs 26.5 (23.26-28.38) days, p<0.001. Interestingly this was despite those with pre-intubation HFNC requiring a significantly greater duration of invasive ventilation - median (IQR) of 115.67 (179-184) hours vs 44 (16-89) hours, p<0.001.

Conclusion

HFNC therapy can safely be used in the initial phases of a respiratory illness in a paediatric population. These children may progress to require a longer course of invasive ventilation but with an overall shorter PICU stay.

Background

Pediatric acute respiratory distress syndrome (PARDS) has been recognized as a burden for critically ill pediatric patients. Previously, the definitions of PARDS were referenced from adults. In 2015, the Pediatric Acute Lung Injury Consensus Conference (PALICC) developed new criteria which were specific for the pediatric group.

Objectives

To examine the incidence and the factors predicting the severity and mortality of ARDS according to PALICC definition in a single tertiary center in Thailand.

Methods

Children aged 1 month to 15 years with acute respiratory failure admitted to the Pediatric intensive care unit (PICU) in Songklanagarind Hospital from January 2013 to December 2016 were reviewed retrospectively.

Results

129 patients (7.4%) were diagnosed as PARDS using the PALICC definition whereas 97 patients (5.5%) by using Berlin definition. From PALICC definition; fifty-seven (44.2%) patients were mild, 35 (27.1%) were moderate, and 37 (28.1%) were severe. After multivariable analysis was performed, factors significantly associated with moderate to severe disease were PRISM III score (p =0.004), underlying oncologic/hematologic disorder (p=0.012), and serum albumin level (p=0.006). The 30-day all-cause mortality rate was 51.2% (66/129). The predictors of mortality were the PRISM III score (p=0.017), underlying oncologic/hematologic disorder (p=0.002), receiving systemic steroid (p=0.019), having airleak syndrome (p=0.008), and presenting with multiorgan dysfunction (p=0.003).

Conclusion

The incidence and mortality rate of PARDS in a developing country are high. The oncologic/hematologic comorbidity had a significant impact on severity and mortality.

Background

Prolonged duration of mechanical ventilation can be associated with complications and an increased risk of extubation failure. Adult studies showed that the maximal inspiratory pressure (MIP) and inspiratory occlusion pressure after 100ms (P100) can predict extubation outcome.

Objectives

To study the level and time course of MIP and P100 during mechanical ventilation in paediatrics and to study its clinical correlate.

Methods

Observational pilot-study in spontaneous breathing and mechanically ventilated children aged <18 years. MIP and P100 was measured during a maximum of five days before extubation. During an occlusion test available on the ventilator, the inspiratory valve was closed during 3-5 inspirations. This manoeuvre was repeated twice and the most negative value was considered as best of three.

Results

A total of 104 patients were included in this study. Median MIP and P100 on day of extubation was -16cm H2O (IQR -20 - -10) and -5cm H2O (-7 - -4), respectively. A significant improvement of MIP (p=0.036) on day of extubation was found. Ventilation duration did affect the level of MIP and P100. No correlation was found between the level of MIP and P100 and age and no differences were found between patients who failed and succeed extubation.

Conclusion

Measuring MIP and P100 during mechanical ventilation in paediatrics can give the clinician insight in respiratory muscle strength when extubation is to be expected. However, predicting extubation success is still to be wished for.

Background

Most paediatric asthma guidelines offer evidence-based or best practice approaches to the management of asthma exacerbations but struggle with an evidence-based approach for severe acute asthma (SAA). The current practices in children with SAA who are admitted to a paediatric intensive care unit (PICU) vary greatly between PICUs worldwide.

Objectives

The aim of this study is to investigate the current management practices concerning children with SAA admitted to a PICU in Europe.

Methods

Cross-sectional electronic survey across European PICUs that admit children with SAA aged 0-18 years.

Results

Thirty-seven PICUs from 11 European countries responded to the survey. In 8 PICUs (22%) a written guideline for the management of SAA children was not available. In the majority of the PICUs (95-100%) SAA treatment consisted of nebulization with beta-agonists and anticholinergics, systemic corticosteroids and intravenous (IV) magnesium sulphate (MgSO₄). In 7 PICUs (19%) a loading dose of a short-acting beta agonist was part of the SAA treatment. Variations existed mainly in the use of adjunct therapies (respiratory support and medication). An asthma severity score to assess the SAA severity was used in 18 PICUs (49%), with 8 different asthma scores used.

Conclusion

Inhaled beta-agonists and anticholinergics, combined with systemic steroids and IV MgSO₄ was central in the treatment of SAA children in nearly all PICUs. Importantly, in 22% of the PICUs written guidelines were not available. Variations existed in the use of adjunct therapies and an asthma severity score. Standardizing SAA guidelines across PICUs in Europe may improve quality of care.

Background

The neuropeptide substance P (SP) is a key mediator of neurogenic inflammation. It is known that SP after binding to NK-1 receptor upregulate this pathological process. However, the presence of SP and NK-1 receptor in acute respiratory distress (ARDS) is unknown.

Objectives

We studied the immunolocalization of SP and its NK-1 receptor in the lung with ARDS and in the healthy lung. To identify differences in the expression, location and distribution of SP and NK-1 receptor in the pathological lung with respect to the healthy lung.

Methods

An immunohistochemical study was performed in 37 lung samples from autopsies performed in patients with ARDS and without pulmonary pathology for SP and NK-1 receptor, assessing the location and distribution of both in the different cells identified in the lung.

Results

In samples from patients with ARDS, the SP and the NK1 receptor are expressed in 90% of the cytoplasms of the pneumocytes with an intensity 3/3, of the alveolar macrophages and in the endothelial cells with intensity 2/3. The alveolar-capillary interstitium is thickened, observing inmurreactividad to SP and NK1R. SP is also expressed in 40% of nuclei with intensity 3/3. By contrast, in samples of lung healthy the SP and the NK-1 receptor expression are very low.

Conclusion

These findings suggest that SP and the NK-1 receptor are involved in the physiopathology of ARDS. Thus, the NK-1 receptor would be a potential therapeutic target and the use of NK-1 receptor antagonists could be considered as a new approach in the treatment of ARDS.

Background

HFNC is increasingly used to prevent the need for invasive ventilation. Little is known of its use post extubation with no formal guidelines for implementation within PICU.

Objectives

To ascertain whether there are clinical pre-extubation predictors for the use of HFNC post extubation in critically ill children.

Methods

Clinical and bedside measurements were recorded on all ventilated admissions, including ventilator requirements and blood gas measurements. Use of HFNC post extubation was assessed in those who survived and did not require long term ventilation via tracheostomy.

Results

522 admissions were recorded during this time period:178 required invasive ventilation. Of these, 10 died and 4 progressed to tracheostomy. The remaining 164 were examined. 51/164 (31.1%) patients received HFNC post-extubation. Children placed on HFNC post extubation appeared to have a greater requirement for oxygen and ventilation on day 1 of their illness. Median (IQR) peak inspiratory pressure (PIP)-24.2 (19.0-27.8) for those extubated to HFNC and 19.1(16.15-23.8) for those without HFNC, p=0.001. Median (IQR) PEEP-5 (5-7) vs 5 (5-5), p<0.001. Median (IQR) FiO₂-0.55 (0.4-0.7) and 0.4 (0.35-0.5), p=0.001.There was no difference in median values for ETCO₂. In the 24 hours prior to extubation, median (IQR) PEEP-5 (5-7) vs 5 (5-5), p=0.012. Median (IQR) FiO₂ -0.4 (0.3-0.55) and 0.35 (0.28-0.4), p=0.041. There were no differences in median values for ETCO₂ or PIP.

Conclusion

A higher need for oxygenation support during invasive ventilation is associated with greater use of HFNC post extubation. Further work is needed to determine whether HFNC subsequently reduces the risk of extubation failure in this cohort.

Background

Impairment of the cerebral blood flow (CBF) may be a key component for secondary neurologic injury in HIE. Influence of positive-pressure ventilation on CBF remains negative but using of Neurally Adjusted Ventilatory Assist looks promising because of better synchronizing and less transpulmonary pressure.

Objectives

To compare the influence of different modes of ventilation on cerebral blood flow in term neonates with HIE.

Methods

172 term neonates with HIE babies were treated in NICU Level III in 2009-2019 using therapeutic hypothermia for 72 hours, assisted positive-pressure ventilation under routine control of acid-base balance, control of systemic, antibiotics, TPN, if needed. Basing on mode of ventilation all the babies were randomly divided on NAVA and control group, receiving PC, SIMV and PRVC respiratory support. To compare the impact of different modes of ventilation on cerebral perfusion we selected such criteria as transfontanel Doppler Resistant Index (RI) and Pulsatile Index (PI) on day 3, after finishing of hypothermia period.

Results

Table 1. Comparative analysis of Doppler indices on the 3^rd day in NAVA and control groups.

The data shows significant differences in RI and PI level between NAVA and control groups.

Conclusion

Neurally Adjusted Ventilatory Assist has significantly less impact on cerebral perfusion in term neonates with HIE comparing to other modes of positive-pressure ventilation.