Diaphragmatic atrophy and dysfunction in critically ill mechanically ventilated children

Impact of Sedation on Ventilator-Induced Diaphragmatic Dysfunction in Extremely Preterm Infants

BACKGROUND

Ventilator-induced diaphragmatic dysfunction is associated with poor patient outcomes. However, the detailed pathophysiology and risk factors underlying the exacerbation of diaphragmatic dysfunction remain unclear. We aimed to evaluate the effect of sedation on diaphragmatic function in extremely preterm infants (EPIs) using ultrasound.

METHODS

A prospective observational study was conducted on 30 EPIs requiring mechanical ventilation within 6 h of birth between July 2020 and September 2023. Diaphragm ultrasound was performed to measure the end-expiratory and end-inspiratory thicknesses of the diaphragm (Tde and Tdi, respectively) and to calculate diaphragm thickening fraction (DTF) after birth and on day 1 of life. Patients receiving continuous fentanyl administration on day 1 were categorized into the sedated group, whereas those not receiving were categorized into the non-sedated group. Changes in Tde, Tdi, and DTF from day 0 to day 1 were compared between groups.

RESULTS

Baseline Tde, Tdi, and DTF did not differ between groups, and both groups showed significant reductions in Tde, Tdi, and DTF from day 0 to day 1. Analysis of covariance after controlling for gestational age and birth weight revealed that sedation significantly affected the change ratios (Tde, -0.343 vs. -0.157, p = 0.038; Tdi, -0.4 vs. -0.169, p = 0.008; DTF, -0.385 vs. -0.194, p = 0.038).

CONCLUSION

In this pilot study, we found that sedation may affect Tde, Tdi, and DTF in ventilated EPIs, and that larger, adequately powered studies are required to validate these preliminary findings.

POCUS in the PICU: A Narrative Review of Evidence-Based Bedside Ultrasound Techniques Ready for Prime-Time in Pediatric Critical Care

Point-of-care ultrasound (POCUS) is an accessible technology that can identify and treat life-threatening pathology in real time without exposing children to ionizing radiation. We aim to review current evidence supporting the use of POCUS by pediatric intensivists with novice-level experience with bedside ultrasound. Current evidence supports the universal adoption of POCUS-guided internal jugular venous catheter placement and arterial line placement by pediatric critical care physicians. Focused cardiac ultrasound performed by PICU physicians who have completed appropriate training with quality assurance measures in place can identify life-threatening cardiac pathology in most children and important physiological changes in children with septic shock. POCUS of the lungs, pleural space, and diaphragm have great potential to provide valuable information at the bedside after validation of these techniques for use in the PICU with additional research. Based on currently available evidence, a generalizable and attainable POCUS educational platform for pediatric intensivists should include training in vascular access techniques and focused cardiac examination. A POCUS educational program should strive to establish credentialing and quality assurance programs that can be expanded when additional research validates the adoption of additional POCUS techniques by pediatric intensive care physicians.

Advancements in imaging techniques for monitoring the respiratory muscles

This review highlights the latest advancements in imaging techniques for monitoring respiratory muscles in critically ill patients. At the bedside, conventional ultrasound has been widely adopted to measure diaphragm thickness, thickening and excursion. It has also been used to assess extradiaphragmatic respiratory muscles, including parasternal intercostal and abdominal muscles. Advanced ultrasound-derived techniques have expanded its applications, enabling the evaluation of tissue velocity (tissue Doppler imaging), stiffness (shear wave elastography), and local tissue displacement (speckle tracking). Facility-based imaging modalities such as magnetic resonance imaging and chest tomography provide complementary insights into respiratory muscles structure and function, offering valuable information for evaluating the effects of therapeutic interventions. Finally, imaging techniques have emerged as valuable tools for evaluating the metabolic demands of respiratory muscles, with advanced methods such as positron emission tomography and contrast-enhanced ultrasound showing significant potential.

Clinical study on the predictive utility of high flow CPAP in weaning from prolonged mechanical ventilation in critical paediatric surgery patients

INTRODUCTION AND OBJECTIVES

Weaning paediatric patients from mechanical ventilation (MV) often results in extubation failure (EF) (14%-22%) and 2% of patients will require tracheostomy (2%).

METHODS

We performed an observational study in 115 critically ill patients in whom a novel high-flow CPAP (CPAP-ANRI) system was connected to the tracheal tube during ventilation (CPAP + TI). After extubation, the same system was connected to various interfaces.

RESULTS

Mean (± SD) age was 31 ± 49 months, PRISM-III score was 2.9 ± 2.4, and duration of intermittent positive pressure ventilation with tracheal intubation (IPPV + TI) was 6 ± 5.6 days followed by CPAP + TI for 1.4 ± 1.7 days. The initial rate of EF was 10.4% for either haemodynamic (n = 4) or respiratory (n= 8) reasons, although the final rate of EF requiring tracheostomy was only 0.8%. After progressing from IPPV + TI to CPAP + TI, PO2/FiO2 values in successfully extubated patients immediately increased by 27% (p < 0.0003) vs only 13% (p > 0.3) in patients presenting EF. Switching to CPAP + TI increased the percentage of patients with pO2/FiO2 > 200, particularly in patients with heart disease, in whom >30% increase in pO2/FiO2 over baseline had a positive predictive value for successful extubation (AUC = 0.708; p = 0.056).

CONCLUSIONS

The CPAP-ANRI device is a simple respiratory aid that is highly effective in optimizing cardiopulmonary interaction to facilitate weaning from MV and identifying most cases in which extubation is likely to be successful.

Serial sonographic assessment of diaphragmatic atrophy and lung injury patterns in mechanically ventilated preterm infants to predict extubation failure: a prospective observational study

Diaphragmatic atrophy (DA) and lung injury (LI) have been associated with mechanical ventilation (MV). We aimed to assess the ultrasonographic changes in diaphragmatic thickness and LI during MV and their prediction for extubation failure in preterm infants. In this prospective observational study, mechanically ventilated preterm infants, < 30 weeks gestation, within the first 24 h of life underwent a baseline, within 24 h of MV, and serial diaphragmatic and lung ultrasounds scans until their first extubation attempt. DA was defined as a decline in pre-extubation expiratory diaphragmatic thickness (DTexp) by ≥ 10% compared to baseline. A total of 251 ultrasound scans were performed on 38 preterm infants with a mean gestational age of 26.6 ± 1.7 weeks. Of these, 18 infants (47%) had DA. Among infants with DA, a pattern of progressive decline in DTexp was associated with a concomitant pattern of increase in the lung ultrasound score (LUS). Infants in the DA group experienced a significantly higher percentage of extubation failure [13 (72%) versus 5 (25%), p = 0.004] compared to the no-DA group. Pre-extubation LUS was significantly higher in the DA compared to the no-DA group (14.2 ± 6.0 versus 10.3 ± 5.2, p = 0.04). Logistic regression analysis controlling for gestational age, pre-extubation weight, and mean airway pressure at extubation showed that LUS [OR 1.27, 95% CI (1.04-1.56), p = 0.02] was an independent predictor of for extubation failure.

CONCLUSION

In this cohort of preterm infants, lung ultrasound score has proved to be a stronger predictor of successful extubation compared to diaphragmatic thickness.

WHAT IS KNOWN

• Ultrasonographic assessment of the diaphragm and lungs is a sensitive tool in diagnosis of ventilator induced diaphragmatic atrophy and lung injury in preterm infants. Accuracy of lung and diaphragmatic ultrasound in predicting extubation outcome in preterm infants is questionable.

WHAT IS NEW

• A pattern of progressive decline in diaphragmatic thickness was associated with a concomitant pattern of increase in the lung ultrasound score in mechanically ventilated preterm infants. Lung ultrasound score has proved to be a stronger predictor of successful extubation compared to diaphragmatic thickness.

What every paediatrician needs to know about mechanical ventilation

Invasive mechanical ventilation (MV) is one of the most practiced interventions in the intensive care unit (ICU) and is unmistakably lifesaving for children with acute respiratory failure (ARF). However, if delivered inappropriately (i.e. ignoring the respiratory system mechanics and not targeted to the need of the individual patient at a specific time point in the disease trajectory), the side effects will outweigh the benefits. Decades of experimental and clinical investigations have resulted in a better understanding of three important detrimental effects of MV. These are ventilation-induced lung injury (VILI), patient self-inflicted lung injury (P-SILI), and ventilation-induced diaphragmatic injury (VIDD). VILI, P-SILI, and VIDD have in common that they occur when there is either too much or too little ventilatory assistance.Conclusion: The purpose of this review is to give the paediatrician an overview of the challenges to prevent these detrimental effects and titrate MV to the individual patient needs.

Association of diaphragmatic dysfunction with duration of mechanical ventilation in patients in the pediatric intensive care unit: a prospective cohort study

BACKGROUND

Mechanical ventilation (MV) can cause diaphragmatic injury and ventilator induced diaphragmatic dysfunction (VIDD). Diaphragm ultrasonography (DU) is increasingly used to assess diaphragmatic anatomy, function and pathology of patients receiving MV in the pediatric intensive care unit (PICU). We report the poor contractile ability of diaphragm during ventilation of critically ill patients in our PICU and the association to prolonged length of MV and PICU stay.

METHODS

Patients who received MV within 24 h of admission to the PICU, expected to undergo continuous MV for more than 48 h and succeeded to extubate were included in the study. DU monitoring was performed daily after the initiation of MV until extubation. Diaphragm thickening fraction (DTF) measured by DU was used as an indicator of diaphragmatic contractile activity. Patients with bilateral DTF = 0% during DU assessment were allocated into the severe VIDD group (n = 26) and the rest were into non-severe VIDD group (n = 29). The association of severe VIDD with individual length of MV, hospitalization and PICU stay were analyzed.

RESULTS

With daily DU assessment, severe VIDD occurred on 2.9 ± 1.2 days after the initiation of MV, and lasted for 1.9 ± 1.7 days. Values of DTF of all patients recovered to > 10% before extubation. The severe VIDD group had a significantly longer duration (days) of MV [12.0 (8.0-19.3) vs. 5.0 (3.5-7.5), p < 0.001] and PICU stay (days) [30.5 (14.9-44.5) vs. 13.0 (7.0-24.5), p < 0.001]. The occurrence of severe VIDD, first day of severe VIDD and length of severe VIDD were significantly positively associated with the duration of MV and PICU stay. The occurrence of severe VIDD on the second and third days after initiation of MV significantly associated to longer PICU stay (days) [43.0 (9.0-70.0) vs. 13.0 (3.0-40.0), p = 0.009; 36.0 (17.0-208.0) vs. 13.0 (3.0-40.0), p = 0.005, respectively], and the length of MV (days) was significantly longer in those with severe VIDD on the third day after initiation of MV [16.5 (7.0-29.0) vs. 5.0 (2.0-22.0), p = 0.003].

CONCLUSIONS

Daily monitoring of diaphragmatic function with bedside ultrasonography after initiation of MV is necessary in critically ill patients in PICU and the influences and risk factors of severe VIDD need to be further studied. (355 words).

Reliability and reference values for diaphragmatic excursion, thickness, and thickening fraction and quadriceps femoris muscle thickness in full-term newborns evaluated by ultrasound

To determine the diaphragm thickness, thickening fraction, and excursion and thickness of the quadriceps femoris muscle in full-term newborns and to evaluate the intra- and interrater reliability of these measurements. This was a prospective, observational clinical study including full-term newborns born within the first 48 h after birth. Serial measurements of the thickness, thickening fraction, and mobility of the diaphragm muscles and the thickness of the quadriceps muscle were obtained using ultrasound images. A total of 69 newborns with a mean gestational age of 39 weeks were included. The following measurements were obtained and are expressed as the mean (standard deviation): inspiratory diaphragm thickness, 0.19 cm (0.04); expiratory diaphragm thickness, 0.16 cm (0.04); diaphragm thickness fraction, 16.70 cm (10.27); diaphragmatic excursion, 0.68 cm (0.22); and quadriceps thickness, 0.99 cm (0.14). Intrarater reliability was assessed using intraclass correlation coefficients (ICCs). Excellent intrarater agreement was observed for the two groups of operators (ICC > 0.86, p < 0.001) for all measurements except for the diaphragm thickening fraction, which showed good agreement for both operator groups (ICC = 0.70, p < 0.001). Regarding interrater reliability, moderate agreement between the raters was observed in the means of all measures (ICC > 0.49, p < 0.001), except for the diaphragm thickening fraction, which showed poor agreement.    Conclusion: Good intrarater and moderate interrater reliability were achieved in ultrasound evaluations of the thickness and mobility of the diaphragm and quadriceps femoris muscles in full-term newborns, demonstrating the feasibility of this technique for clinical use. This pioneering study offers reference values for these muscles in a single study, allowing comparisons between different clinical conditions. What is Known: • Ultrasound is a highly reliable tool for muscle assessment that can be used to assess muscular atrophy in critically ill patients. • Muscle atrophy worsens the patient's condition and has been associated with worse outcomes. What is New: • To our knowledge, this is the first study to jointly evaluate the diaphragm and quadriceps muscle thickness and evaluate the reliability of all measurements. • Our study presents reference values for both muscles, enabling comparisons between different clinical conditions.

Rehabilitation in children with home invasive mechanical ventilation

Children with home invasive mechanical ventilation need special health care and rehabilitation services due to complications caused by both the pulmonary system and physical inactivity. Children who are dependent on invasive mechanical ventilators due to breathing difficulties and lung problems can benefit from rehabilitation programs. Rehabilitation requires a close relationship between the child, parents and/or caregivers, and healthcare professionals. The main goal of rehabilitation is to improve breathing, lung function and overall quality of life. In this review, although full standard approaches have not been determined yet, rehabilitation approaches for children dependent on home-type invasive mechanical ventilator will be discussed.

Evaluation of the combined predictive value of multiple indicators based on diaphragmatic ultrasound using logistic regression and ROC curve in weaning from mechanical ventilation in pediatric patients

Background

Conventional single indicators have low sensitivity and specificity for predicting weaning from mechanical ventilation in pediatric patients, necessitating the establishment of a combined prediction model for predicting weaning outcomes.

Objectives

To explore the combined predictive value of PaO2/FiO2 Ratio (P/F ratio), diaphragm excursion-rapid shallow breathing index (DE-RSBI), diaphragm thickening fraction-rapid shallow breathing index (DTF-RSBI), and Pediatric Critical Illness Score (PCIS) in weaning from mechanical ventilation in pediatric patients.

Methods

Sixty critically ill pneumonia pediatric patients requiring mechanical ventilation treatment from July 2022 to June 2023 at the Second Affiliated Hospital of Jiaxing University were selected. They all underwent a spontaneous breathing trial (SBT) and were divided into the weaning success group (42 cases) and weaning failure group (18 cases) based on the weaning outcome. Parameters including total duration of illness, mechanical ventilation duration, heart rate (HR), P/F ratio, diaphragm excursion (DE), DE-RSBI, diaphragm thickening fraction (DTF), DTF-RSBI, and PCIS were included in univariate and multivariate logistic regression analyses to determine independent factors affecting pediatric weaning success. Receiver operating characteristic (ROC) curves were plotted to evaluate the predictive value of P/F ratio, DE-RSBI, DTF-RSBI, PCIS alone or in combination for weaning success.

Results

Comparing P/F ratio, DE, DE-RSBI, DTF, DTF-RSBI and PCIS, there were statistically significant differences (P < 0.05). Through collinearity analysis and binary logistic regression analysis,P/F ratio [OR = 0.777, 95% CI (0.641,0.941)], DE-RSBI [OR = 1.694, 95% CI (1.172, 2.447)], DTF-RSBI [OR = 1.057, 95% CI (1.002, 1.114)], and PCIS [OR = 0.661, 95% CI (0.445, 0.982)] were identified as independent factors affecting successful weaning(P < 0.05).The regression equation was: LogitP = 73.299-0.253 P/F ratio + 0.525DE-RSBI + 0.055DTF-RSBI-0.43PCIS.The sensitivity of the combined indicator Logit(P) in predicting successful weaning from mechanical ventilation in pediatric patients was 88.9%, with a specificity of 95.2% (optimal cutoff value of 0.511), and the area under the ROC curve (AUC) was 0.960 [95% CI (0.915, 1.000)]. The AUC of the combined prediction model for predicting pediatric weaning was greater than that of P/F ratio, DE-RSBI, DTF-RSBI and PCIS alone (Z values = 9.129, 2.061, 2.075, 8.326, P < 0.05).

Conclusions

In mechanically ventilated pediatric patients, the combined prediction model has better predictive value for weaning success compared to using P/F ratio, DE-RSBI, DTF-RSBI, or PCIS alone.

Macronutrient and Micronutrient Intake in Children with Lung Disease

This review article aims to summarize the literature findings regarding the role of micronutrients in children with lung disease. The nutritional and respiratory statuses of critically ill children are interrelated, and malnutrition is commonly associated with respiratory failure. The most recent nutrition support guidelines for critically ill children have recommended an adequate macronutrient intake in the first week of admission due to its association with good outcomes. In children with lung disease, it is important not to exceed the proportion of carbohydrates in the diet to avoid increased carbon dioxide production and increased work of breathing, which potentially could delay the weaning of the ventilator. Indirect calorimetry can guide the process of estimating adequate caloric intake and adjusting the proportion of carbohydrates in the diet based on the results of the respiratory quotient. Micronutrients, including vitamins, trace elements, and others, have been shown to play a role in the structure and function of the immune system, antioxidant properties, and the production of antimicrobial proteins supporting the defense mechanisms against infections. Sufficient levels of micronutrients and adequate supplementation have been associated with better outcomes in children with lung diseases, including pneumonia, cystic fibrosis, asthma, bronchiolitis, and acute respiratory failure.

The Relationship Between Esophageal Pressure and Diaphragm Thickening Fraction in Spontaneously Breathing Sedated Children: A Feasibility Study

OBJECTIVES

Diaphragm ultrasound is a novel alternative to esophageal pressure measurements in the evaluation of diaphragm function and activity, but data about its reliability in a pediatric setting are lacking. We aimed to compare the esophageal pressure swing (∆P es , gold standard) with the diaphragmatic thickening fraction (DTF) as a measure of inspiratory effort in sedated children. Additionally, we studied the effect of positive end-expiratory pressure (PEEP) on the end-expiratory thickness of the diaphragm (DT ee ).

DESIGN

Prospective open-label non-randomized interventional physiological cohort study.

SETTING

Operating room in tertiary academic hospital.

PATIENTS

Children 28 days to 13 years old scheduled for elective surgery with general anesthesia, spontaneously breathing through a laryngeal mask airway, were eligible for inclusion. Exclusion criteria were disorders or previous surgery of the diaphragm, anticipated difficult airway or acute cardiopulmonary disease. All measurements were performed prior to surgery.

INTERVENTIONS

Patients were subjected to different levels of respiratory load, PEEP and anesthetic depth in a total of seven respiratory conditions.

MEASUREMENTS AND MAIN RESULTS

The esophageal pressure and diaphragm thickening fraction were simultaneously recorded for five breaths at each respiratory condition. The relation between ∆P es and DTF was studied in a mixed model. We analyzed 407 breaths in 13 patients. Both DTF ( p = 0.03) and ∆Pes ( p = 0.002) could detect respiratory activity, and ∆P es and DTF were associated across respiratory conditions ( p < 0.001; R2 = 31%). With increasing inspiratory load, ∆P es increased significantly, while DTF did not ( p = 0.08). Additionally, DT ee did not differ significantly between 10, 5, and 0 cm H 2 O PEEP ( p = 0.08).

CONCLUSIONS

In spontaneously breathing sedated children and across different respiratory conditions, DTF could differentiate minimal or no inspiratory effort from substantial inspiratory effort and was associated with ∆P es . Increased efforts resulted in higher ∆P es but not larger DTF.

Tests and Indices Predicting Extubation Failure in Children: A Systematic Review and Meta-analysis

INTRODUCTION

There is lack of consensus on what constitutes best practice when assessing extubation readiness in children. This systematic review aims to synthesize data from existing literature on pre-extubation assessments and evaluate their diagnostic accuracies in predicting extubation failure (EF) in children.

METHODS

A systematic search in PubMed, EMBASE, Web of Science, CINAHL, and Cochrane was performed from inception of each database to 15 July 2021. Randomized controlled trials or observational studies that studied the association between pre-extubation assessments and extubation outcome in the pediatric intensive care unit population were included. Meta-analysis was performed for studies that report diagnostic tests results of a combination of parameters.

RESULTS

In total, 41 of 11,663 publications screened were included (total patients, n = 8111). Definition of EF across studies was heterogeneous. Fifty-five unique pre-extubation assessments were identified. Parameters most studied were: respiratory rate (RR) (13/41, n = 1945), partial pressure of arterial carbon dioxide (10/41, n = 1379), tidal volume (13/41, n = 1945), rapid shallow breathing index (RBSI) (9/41, n = 1400), and spontaneous breathing trials (SBT) (13/41, n = 5652). Meta-analysis shows that RSBI, compliance rate oxygenation pressure (CROP) index, and SBT had sensitivities ranging from 0.14 to 0.57. CROP index had the highest sensitivity [0.57, 95% confidence interval (CI) 0.4-0.73] and area under curve (AUC, 0.98). SBT had the highest specificity (0.93, 95% CI 0.92-0.94).

CONCLUSIONS

Pre-extubation assessments studied thus far remain poor predictors of EF. CROP index, having the highest AUC, should be further explored as a predictor of EF. Standardizing the EF definition will allow better comparison of pre-extubation assessments.

Accuracy of lung and diaphragm ultrasound in predicting successful extubation in extremely preterm infants: A prospective observational study

OBJECTIVE

Chest ultrasound has emerged as a promising tool in predicting extubation readiness in adults and children, yet its utility in preterm infants is lacking. Our aim was to assess the utility of lung ultrasound severity score (LUSS) and diaphragmatic function in predicting extubation readiness in extremely preterm infants.

STUDY DESIGN

In this prospective cohort study, preterm infants < 28 weeks gestational age (GA) who received invasive mechanical ventilation for ≥12 h were enrolled. Chest ultrasound was performed before extubation. The primary outcome was lung ultrasound accuracy for predicting successful extubation at 3 days. Descriptive statistics and logistic regression were done using SPSS version 22.

RESULTS

We enrolled 45 infants, of whom 36 (80%) were successfully extubated. GA and postmenstrual age (PMA) at extubation were significantly higher in the successful group. The LUSS was significantly lower in the successful group compared to failed group (11.9 ± 3.2 vs. 19.1 ± 3.1 p < 0.001). The two groups had no statistically significant difference in diaphragmatic excursion or diaphragmatic thickness fraction. Logistic regression analysis controlling for GA and PMA at extubation showed LUSS was an independent predictor for successful extubation (odd ratio 0.46, 95% confidence interval [0.23-0.9], p = 0.02). The area under the receiver operating characteristic curve was 0.95 (p ˂ 0.001) for LUSS, and a cut-off value of ≥15 had 95% sensitivity and 85% specificity in detecting extubation failure.

CONCLUSION

In extremely preterm infants, lung ultrasound has good accuracy for predicting successful extubation. However, diaphragmatic measurements were not reliable predictors.

Diaphragmatic Thickening Fraction by Ultrasound in Mechanically Ventilated Pediatric Patients: Pilot Observations During Spontaneous Breathing Trials

OBJECTIVES

In critically ill, mechanically ventilated adults, diaphragmatic atrophy and reduced diaphragmatic thickening fraction (DTF) has been associated with poor extubation outcomes. Diaphragmatic ultrasound assessment in critically ill pediatric patients shows similar results, though studies are on-going. We sought to explore the feasibility and utility of using DTF, obtained during a spontaneous breathing trial (SBT) in predicting weaning outcomes.

METHODS

We conducted a prospective, observational study in a single-center tertiary noncardiac pediatric intensive care unit (PICU) in a children's hospital. Mechanically ventilated pediatric patients were included except for those with preexisting conditions of neuromuscular weakness, diaphragm paresis, or chronic respiratory failure requiring non-invasive or invasive mechanical ventilation at baseline. A convenience sample of 38 patients were included in the study.

RESULTS

Weaning failure occurred in 10/38 (26%) instances with 9/38 (24%) occurring due to failed SBT and 1/38 (2%) due to failed extubation requiring reintubation. Median DTF was 24% (IQR: 12-33). DTF was significantly lower in instances of failed SBT, 12% compared to 27% (P < .01). The odds ratio (OR) of SBT failure utilizing: TF < 25% is 12 (CI: 1.33-108.0, Z-score: 2.22, P = .027), TV <5 mL/kg was 10.4 (CI: 1.76-61.67, Z-score: 2.58, P = .01), and combined TV <5 mL/kg and TF < 25% is 17.6 (CI: 1.19-259.61, Z-score: 2.09, P = .04).

CONCLUSIONS

Our preliminary study suggests that ultrasound measurements of diaphragm thickening fraction during spontaneous breaths in mechanically ventilated pediatric patients may be a useful addition in predicting weaning readiness.

Comparing ventilation modes by electrical impedance segmentography in ventilated children

Electrical impedance segmentography offers a new radiation-free possibility of continuous bedside ventilation monitoring. The aim of this study was to evaluate the efficacy and reproducibility of this bedside tool by comparing synchronized intermittent mandatory ventilation (SIMV) with neurally adjusted ventilatory assist (NAVA) in critically-ill children. In this prospective randomized case-control crossover trial in a pediatric intensive care unit of a tertiary center, including eight mechanically-ventilated children, four sequences of two different ventilation modes were consecutively applied. All children were randomized into two groups; starting on NAVA or SIMV. During ventilation, electric impedance segmentography measurements were recorded. The relative difference of vertical impedance between both ventilatory modes was measured (median 0.52, IQR 0-0.87). These differences in left apical lung segments were present during the first (median 0.58, IQR 0-0.89, p = 0.04) and second crossover (median 0.50, IQR 0-0.88, p = 0.05) as well as across total impedance (0.52 IQR 0-0.87; p = 0.002). During NAVA children showed a shift of impedance towards caudal lung segments, compared to SIMV. Electrical impedance segmentography enables dynamic monitoring of transthoracic impedance. The immediate benefit of personalized ventilatory strategies can be seen when using this simple-to-apply bedside tool for measuring lung impedance.

Diaphragm ultrasound to predict weaning outcome: systematic review and meta-analysis

Proper timing for discontinuation of mechanical ventilation is of great importance, especially in patients with previous weaning failures. Different indices obtained by ultra-sonographic evaluation of the diaphragm muscle have improved determination of weaning success. The aim of the present systematic review was to evaluate and compare the accuracy of the diagnostic indices obtained by ultrasonographic examination, including diaphragm thickening fraction (DTF), diaphragmatic excursion (DE) and the rapid shallow breathing index (RSBI). A systematic literature search (Web of Science, MEDLINE, Embase and Google Scholar) was performed to identify original articles assessing diaphragm muscle features including excursion and thickening fraction. A total of 2738 citations were retrieved initially; available data of 19 cohort studies (1114 patients overall) were included in the meta-analysis, subdivided into groups based on the ultrasonographic examination type. Our results showed the superiority of the diagnostic accuracy of the DTF in comparison to the DE and the RSBI. Data on the combination of the different indices are limited. Diaphragmatic ultrasound is a cheap and feasible tool for diaphragm function evaluation. Moreover, DTF in the assessment of weaning outcome provides more promising outcomes, which should be evaluated more meti-culously in future randomised trials.

Evolution of inspiratory muscle function in children during mechanical ventilation

BACKGROUND

There is no universally accepted method to assess the pressure-generating capacity of inspiratory muscles in children on mechanical ventilation (MV), and no study describing its evolution over time in this population.

METHODS

In this prospective observational study, we have assessed the function of the inspiratory muscles in children on various modes of MV. During brief airway occlusion maneuvers, we simultaneously recorded airway pressure depression at the endotracheal tube (ΔPaw, force generation) and electrical activity of the diaphragm (EAdi, central respiratory drive) over five consecutive inspiratory efforts. The neuro-mechanical efficiency ratio (NME, ΔPaw/EAdimax) was also computed. The evolution over time of these indices in a group of children in the pediatric intensive care unit (PICU) was primarily described. As a secondary objective, we compared these values to those measured in a group of children in the operating room (OR).

RESULTS

In the PICU group, although median NMEoccl decreased over time during MV (regression coefficient - 0.016, p = 0.03), maximum ΔPawmax remained unchanged (regression coefficient 0.109, p = 0.50). Median NMEoccl at the first measurement in the PICU group (after 21 h of MV) was significantly lower than at the only measurement in the OR group (1.8 cmH2O/µV, Q1-Q3 1.3-2.4 vs. 3.7 cmH2O/µV, Q1-Q3 3.5-4.2; p = 0.015). Maximum ΔPawmax in the PICU group was, however, not significantly different from the OR group (35.1 cmH2O, Q1-Q3 21-58 vs. 31.3 cmH2O, Q1-Q3 28.5-35.5; p = 0.982).

CONCLUSIONS

The function of inspiratory muscles can be monitored at the bedside of children on MV using brief airway occlusions. Inspiratory muscle efficiency was significantly lower in critically ill children than in children undergoing elective surgery, and it decreased over time during MV in critically ill children. This suggests that both critical illness and MV may have an impact on inspiratory muscle efficiency.