Diagnosis of Abnormal Diaphragm Motion after Cardiothoracic Surgery: Ultrasound Performed by a Cardiac Intensivist vs. Fluoroscopy

Diaphragmatic Ultrasound in Children With Asthma Exacerbations

OBJECTIVES

Asthma is a leading cause of pediatric emergency department visits, yet few tools exist to objectively measure asthma severity. Diaphragmatic ultrasound (DUS) is a novel method of assessing respiratory distress; however, data are lacking for children.Our primary aim was to determine if diaphragmatic excursion (DE), diaphragmatic thickening (DT), or diaphragmatic thickening fraction (TF) correlated with asthma severity as determined by the Pediatric Respiratory Assessment Measure (PRAM) score. Secondarily, we examined if these parameters correlated with need for respiratory support and evaluated interrater reliability.

METHODS

We conducted a prospective study of children 5-18 years presenting to a pediatric emergency department with an asthma exacerbation. Diaphragmatic ultrasound was performed by a trained pediatric emergency medicine sonologist in subcostal (DE) and midaxillary (DT). Thickening fraction was calculated from DT values as previously described in literature. To evaluate interrater reliability, a subset of subjects had DUS performed by a second sonologist.

RESULTS

We enrolled 47 subjects for a total of 51 encounters. The mean age was 9.1 ± 3.7 years. Twenty-five (49%) had mild, 24 (47%) had moderate, and 2 (4%) had severe asthma. There was a significant difference in midaxillary DT and TF between children with mild and moderate asthma (P = 0.02; mean difference, 0.2 mm; 95% confidence interval [CI], 0.03-0.4 and P = 0.02; mean difference, 0.11 mm; 95% CI, 0.02-0.2, respectively). No difference was found in subcostal DE (P = 0.43; mean difference, 1.4 mm; 95% CI, -2.1 to 4.8). No association was found between use of positive pressure and DUS parameters. Fourteen encounters had 2 sonologists perform DUS, with strong interrater reliability found for midaxillary DT (Pearson correlation, 0.56) and poor association for subcostal DE (Pearson correlation, 0.18).

CONCLUSIONS

In this pilot study, we conclude that DUS may be helpful in assessing severity of asthma. The midaxillary view assessment for DT and TF had the best correlation with asthma severity and the best interrater reliability. Future studies may benefit from focusing on the midaxillary view for DT and TF.

[Diaphragmatic ultrasonography for the pulmonologist: Technique and clinical use]

INTRODUCTION

Ultrasonography is an emerging tool that helps to assess diaphragmatic function. It is now widely used in ICUs to predict weaning from mechanical ventilation. Ultrasonography is readily available, harmless (no radiation), and repeatable with good interoperator reproducibility. Over the past few years, ultrasonography has seen increasing use in patients with chronic pulmonary pathologies.

STATE OF THE ART

The aim of this review is (1) to describe the ultrasound techniques used to assess diaphragmatic excursion and thickening, (2) to indicate the expected, normal values in healthy patients, and (3) to summarize the main findings and clinical applications in treatment of chronic respiratory disorders.

CONCLUSIONS

Chronic pulmonary diseases are associated with diaphragmatic dysfunction that can be assessed with ultrasound. Diaphragmatic dysfunction is primary in neuromuscular disorders and secondary to respiratory disease in other chronic pulmonary conditions (COPD, ILD). Ultrasound is correlated with the severity of the underlying disease (functional and clinical parameters).

PERSPECTIVES

The prognostic interest of diaphragm ultrasonography remains to be established, after which its utilization should become routine.

Changes in diaphragmatic ultrasonography findings and their association with postoperative complications in children undergoing pulmonary resection: A single-centre, prospective, observational study

BACKGROUND

Few studies have investigated the changes in diaphragmatic function and their association with postoperative pulmonary complications (PPCs) in paediatric patients after lung resection.

OBJECTIVE

This study aimed to evaluate diaphragmatic function using ultrasound after lung resection and its influence on PCCs in children.

DESIGN

Prospective observational study.

SETTING

A tertiary children's hospital.

PATIENTS

Children aged 6 years or less who were scheduled for video-assisted thoracoscopic lung resection.

INTERVENTION

Ultrasonographic measurements of diaphragmatic excursion (DE) and thickening fraction (TF) were performed for three epochs: before anaesthesia induction (T0), 1 h postoperatively (T1) and 24 h postoperatively (T2). The thickening fraction is calculated from the thickness of the diaphragm at end expiration and end inspiration at each time point. DE T1 /DE T0 , DE T2 /DE T0 , TF T1 /TF T0 and TF T2 /TF T0 (%) were calculated. The incidence of PCCs was also determined.

MAIN OUTCOME MEASURES

The primary outcomes were changes in diaphragmatic excursion and thickening fraction over time, from T0 to T2. The secondary outcomes were the association between ultrasound parameters of diaphragm function and the occurrence of early PPCs within 3 days.

RESULTS

Data from 74 children were analysed. On the operated side, both diaphragmatic excursion and thickening fraction decreased at T1 and recovered slightly at T2, and were significantly lower than the T0 values. Children with PPCs had significantly lower DE T2 /DE T0 and TF T2 /TF T0 scores on the operated side than those without PPCs. According to the receiver operating characteristic analysis, the DE T2 /DE T0 (< 61.1%) on the operated side was associated with PPCs with an area under the curve of 0.764.

CONCLUSIONS

Peri-operative diaphragmatic function assessed by ultrasonography changed after lung resection in children. The diaphragmatic excursion and thickening fraction decreased postoperatively, and a prolonged decrease in diaphragmatic excursion was associated with pulmonary complications after lung surgery in children.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov, NCT04400370.

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.

Diaphragm Ultrasound in Critically Ill Patients on Mechanical Ventilation—Evolving Concepts

Mechanical ventilation (MV) is a life-saving respiratory support therapy, but MV can lead to diaphragm muscle injury (myotrauma) and induce diaphragmatic dysfunction (DD). DD is relevant because it is highly prevalent and associated with significant adverse outcomes, including prolonged ventilation, weaning failures, and mortality. The main mechanisms involved in the occurrence of myotrauma are associated with inadequate MV support in adapting to the patient’s respiratory effort (over- and under-assistance) and as a result of patient-ventilator asynchrony (PVA). The recognition of these mechanisms associated with myotrauma forced the development of myotrauma prevention strategies (MV with diaphragm protection), mainly based on titration of appropriate levels of inspiratory effort (to avoid over- and under-assistance) and to avoid PVA. Protecting the diaphragm during MV therefore requires the use of tools to monitor diaphragmatic effort and detect PVA. Diaphragm ultrasound is a non-invasive technique that can be used to monitor diaphragm function, to assess PVA, and potentially help to define diaphragmatic effort with protective ventilation. This review aims to provide clinicians with an overview of the relevance of DD and the main mechanisms underlying myotrauma, as well as the most current strategies aimed at minimizing the occurrence of myotrauma with special emphasis on the role of ultrasound in monitoring diaphragm function.

New International Guidelines and Consensus on the Use of Lung Ultrasound

Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different fields (clinical and technical) reviewed and updated the original international consensus for point-of-care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.

Ultrasound imaging of diaphragmatic motion

The diaphragm is the key muscle of respiration, especially in infants. Diaphragmatic dysfunction and paralysis can have significant implications for medical management and treatment, and they can be challenging to diagnose by clinical parameters alone. Multiple imaging modalities are useful for assessing the diaphragm, but US - specifically M-mode US - offers several distinct advantages and few limitations compared to fluoroscopy, radiography, CT and MRI. The purpose of this manuscript is to discuss the pathophysiology of the diaphragm, review common indications for dynamic diaphragmatic US, describe optimal imaging technique, and discuss how to avoid imaging pitfalls.

Diagnostic Utility of Point-of-Care Ultrasound in the Pediatric Cardiac Intensive Care Unit

Purpose of Review

Recent Findings

Summary

Supplementary Information

Diaphragm Dysfunction after Cardiac Surgery: Insights from Ultrasound Imaging during Cardiac Rehabilitation

Diaphragm dysfunction is common after cardiac surgery and can be evaluated with ultrasonography (US). We aimed at assessing with US the incidence of diaphragmatic dysfunction and the impact of cardiovascular rehabilitation (CR) on its recovery. A single-center cohort study was performed. Patients were enrolled after cardiac surgery. The 6-min walking test (6MWT) and diaphragm US were performed at CR admission and after 10 rehabilitative sessions. One hundred eighty-five patients were eligible for final analysis. One hundred thirty-one patients (70.8%) were found to have diaphragm dysfunction (excursion <2 cm). After CR, 68 patients regained normal diaphragmatic function; those with persistent dysfunction had a lower level of functional performance on the 6MWT (metabolic equivalents of tasks: 3.3 vs. 3.6, p = 0.013). The patients who underwent combined surgery (adjusted odds ratio [aOR] = 4.09, p = 0.001) and those with post-operative pneumothorax (aOR = 3.02, p = 0.042) were at increased risk of failure to improve diaphragmatic excursion. US parameters were more powerful tools in predicting diaphragmatic evolution compared with the 6MWT indexes: baseline diaphragm excursion and thickening fraction were associated with complete diaphragmatic functional recovery after CR (aOR = 9.101, p < 0.001, and aOR = 1.058, p = 0.020 respectively). US is a valuable tool for the assessment of post-operative diaphragmatic dysfunction and can identify patients at risk of diaphragmatic recovery failure.

Type 2 respiratory failure secondary to left hemidiaphragmatic paralysis

A 73-year-old man presented to the emergency department with worsening orthopnoea and exertional dyspnoea. He denied any other cardiorespiratory symptoms. The patient had a body mass index (BMI) of 23.3 kg·m⁻² (height 163 cm, weight 62 kg). Lung function tests 3 months before admission showed a ratio of forced expiratory volume in 1 s (FEV₁) to forced vital capacity (FVC) of 88%. He had a past medical history of hypothyroidism, for which he was on levothyroxine 50 μg daily, and type 2 diabetes mellitus, for which he was on metformin 500 mg twice daily. Past surgical history included a gastrectomy 3 years prior to admission performed for gastric cancer, which was subsequently complicated by a subphrenic abscess, pancreatitis and residual pancreatic insufficiency. The patient was a lifelong non-smoker, worked in construction, reared birds as a hobby, and lived in an urban area. He was not on any other medication.

This case describes an uncommon presentation of type 2 respiratory failure secondary to left hemidiaphragmatic paralysis. Emphasis is on the multitude of possible causes of hemidiaphragmatic paralysis and how to manage such a presentation.https://bit.ly/3Mcd2XI

Diaphragmatic Function Assessed by Bed Side Ultrasonography in Patients with Sepsis or Septic Shock Admitted to Intensive Care Unit

BACKGROUND: Sepsis and septic shock are major problems faced the healthcare systems all over the world every year. The ultrasound (US) is a simple, non-invasive, easily accessible technique, and showed great accuracy in diaphragm assessment. AIM: We evaluated the diaphragmatic function assessed by US in patients with sepsis and septic shock and correlated these assessments with different parameters. MATERIALS AND METHODS: A prospective observational study carried out on 30 patients admitted to the intensive care unit (ICU) diagnosed with sepsis and/or septic shock. Both diaphragmatic excursion (DE) and thickness fraction (diaphragm thickening fraction [TDI] %) were assessed by US on admission and every 48 h along the patients’ ICU stay. RESULTS: In the current study, there was a statistically significant reverse relationship between mortality and the different diaphragmatic function parameters (DE on admission, average DE, on admission TDI%, average TDI%). On the other hand, the DE (on admission and average) showed a statistically significant reverse relation with the need and duration of mechanical ventilation (MV) while the TDI% showed a statistically significant reverse relation only with the duration of MV. Besides, there was a statistically significant direct relationship between successful weaning from MV and all the measured parameters. CONCLUSION: We proposed that the diaphragmatic function parameters (DE on admission, average DE, on admission TDI% and average TDI%) assessed by US of septic ICU patients could be used as a predictor of the need, duration, and successful weaning from MV and also as a predictor of mortality.

Ultrasound Protocols to Assess Skeletal and Diaphragmatic Muscle in People Who Are Critically Ill: A Systematic Review

This study aims to review published studies that use protocols and ultrasound measurements to evaluate skeletal and diaphragmatic muscles in patients who are critically ill. We searched for references on databases through September 2020 and included in our systematic review studies that used muscular ultrasound to assess skeletal or diaphragm muscles in patients who are critically ill. Seventy-six studies were included, 32 (1720 patients) using skeletal-muscle ultrasound and 44 (2946 patients) using diaphragmatic-muscle ultrasound, with a total of 4666 patients. The population is predominantly adult men. As for designs, most studies (n = 62) were cohort studies. B-mode B was dominant in the evaluations. Medium-to-high frequency bands were used in the analysis of peripheral muscles and medium-to-low frequency bands for diaphragmatic muscles. Evaluation of the echogenicity, muscle thickness and pennation angle of the muscle was also reported. These variables are important in the composition of the diagnosis of muscle loss. Studies demonstrate great variability in their protocols, and sparse description of the important variables that can directly interfere with the quality and validity of these measures. Therefore, a document is needed that standardizes these parameters for ultrasound assessment in patients who are critically ill.

The Utility of Point-of-Care Ultrasound in the Pediatric Intensive Care Unit

Objectives: Point of care ultrasound (POCUS) in adult critical care environments has become the standard of care in many hospitals. A robust literature shows its benefits for both diagnosis and delivery of care. The utility of POCUS in the pediatric intensive care unit (PICU), however, is understudied. This study describes in a series of PICU patients the clinical indications, protocols, findings and impact of pediatric POCUS on clinical management. Design: Retrospective analysis of 200 consecutive POCUS scans performed by a PICU physician. Patients: Pediatric critical care patients who required POCUS scans over a 15-month period. Setting: The pediatric and cardiac ICUs at a tertiary pediatric care center. Interventions: Performance of a POCUS scan by a pediatric critical care attending with advanced training in ultrasonography. Measurement and Main Results: A total of 200 POCUS scans comprised of one or more protocols (lung and pleura, cardiac, abdominal, or vascular diagnostic protocols) were performed on 155 patients over a 15-month period. The protocols used for each scan reflected the clinical question to be answered. These 200 scans included 133 thoracic protocols, 110 cardiac protocols, 77 abdominal protocols, and 4 vascular protocols. In this series, 42% of scans identified pathology that required a change in therapy, 26% confirmed pathology consistent with the ongoing plans for new therapy, and 32% identified pathology that did not result in initiation of a new therapy. Conclusions: POCUS performed by a trained pediatric intensivist provided useful clinical information to guide patient management.

The Use of Angle-Independent M-Mode in the Evaluation of Diaphragmatic Excursion: Towards Improved Accuracy

Assessment of diaphragmatic function has been well described in the intensive care setting as well as in emergency medicine and pediatrics. Conventional M-mode evaluation of diaphragmatic excursion is frequently associated with over and under-estimations of diaphragmatic excursion. Angle-independent M-mode allows free rotation and movement of the analysis line to obtain M-mode images in a direction that more accurately reflects diaphragmatic excursion. In order to provide a standardized approach to the evaluation of diaphragmatic excursion with angle-independent M-mode, we propose a landmark-based approach utilizing the spine in order to target the same diaphragmatic segment consistently throughout the diaphragmatic analysis. While the proposed approach is not intended to replace current methods, it may improve accuracy and inter-rater reliability. The relevant background, as well as three patient cases, are presented demonstrating the use of a landmark-based approach in the emergency department. Angle-independent M-mode may provide a more accurate and consistent evaluation of diaphragmatic excursion, an examination that can be used to guide clinical care and anticipate outcomes.

A narrative review of diaphragmatic ultrasound in pediatric critical care

The use of point of care ultrasound (POCUS) at the bedside has increased dramatically within emergency medicine and in critical care. Applications of POCUS have spread to include diaphragmatic assessments in both adults and children. Diaphragm POCUS can be used to assess for diaphragm dysfunction (DD) and atrophy or to guide ventilator titration and weaning. Quantitative, semi-quantitative and qualitative measurements of diaphragm thickness, diaphragm excursion, and diaphragm thickening fraction provide objective data related to DD and atrophy. The potential for quick, noninvasive, and repeatable bedside diaphragm assessments has led to a growing amount of literature on diaphragm POCUS. To date, there are no reviews of the current state of diaphragm POCUS in pediatric critical care. The aims of this narrative review are to summarize the current literature regarding techniques, reference values, applications, and future innovations of diaphragm POCUS in critically ill children. A summary of current practice and future directions will be discussed.

Incidence of early diaphragmatic dysfunction after lung transplantation: results of a prospective observational study

BACKGROUND

Diaphragmatic dysfunction is common after cardiothoracic surgery, but few studies report its incidence and consequences after lung transplantation. We aimed to estimate the incidence of diaphragmatic dysfunction using ultrasound in lung transplant patients up to 3 months postoperatively and evaluated the impact on clinical outcomes.

METHODS

This was a single-center prospective observational cohort study of 27 lung transplant recipients using diaphragmatic ultrasound preoperatively, at 1 day, 1 week, 1 month, and 3 months postoperatively. Diaphragmatic dysfunction was defined as excursion < 10 mm in men and < 9 mm in women during quiet breathing. Clinical outcomes measured included duration of mechanical ventilation, length of stay (LOS) in Intensive Care (ICU), and hospital LOS.

RESULTS

Sixty-two percentage of recipients experienced new, postoperative diaphragmatic dysfunction, but the prevalence fell to 22% at 3 months. No differences in clinical outcomes were found between those with diaphragmatic dysfunction compared to those without. Patients who experienced diaphragmatic dysfunction at 1 day postoperatively were younger and had a lower BMI than those who did not.

CONCLUSIONS

Diaphragmatic dysfunction is common after lung transplant, improves significantly within 3 months, and did not impact negatively on duration of mechanical ventilation, LOS in ICU or hospital, or discharge destination.

Point-of-Care Ultrasound Measurement of Diaphragm Thickening Fraction as a Predictor of Successful Extubation in Critically Ill Children

Ventilation-induced diaphragm dysfunction can delay weaning from mechanical ventilation. Identifying the optimal time for extubation has always been a challenge for intensivists. Diaphragm ultrasound is gaining immense popularity as a surrogate to measure diaphragm function. We attempted to assess the utility of diaphragm function in predicting extubation success using point-of-care ultrasound examination. We conducted a prospective observational study in a single-center tertiary care pediatric intensive care unit (PICU). All children aged between 1 month and 16 years admitted to the PICU and who underwent invasive mechanical ventilation for more than 24 hours were included in the study. Children who died during mechanical ventilation and those with conditions affecting diaphragm function like neuromuscular disorders, pneumothorax, chronic respiratory diseases, and intraabdominal hypertension were excluded from the study. Diaphragm thickening fraction (DTf) was measured during spontaneous breathing trial and correlated to predict extubation success. We found that DTf is an independent predictor of extubation success. DTf more than or equal to 20% was associated with extubation success with a positive predictive value of 85%. The area under the curve for DTf showed good accuracy.

Outcome analysis of a conservative approach to diaphragmatic paralysis following congenital cardiac surgery in neonates and infants: a bicentric retrospective study

 

OBJECTIVES

Diaphragmatic paralysis following congenital cardiac surgery is associated with significant morbidity and mortality. Spontaneous recovery of diaphragmatic function has been described, contrasting with centres providing early diaphragmatic plication. We aimed to describe the outcomes of a conservative approach, as well as to identify factors associated with a failure of the strategy.

METHODS

This is a retrospective study of patients admitted after cardiac surgery and suffering unilateral diaphragmatic paralysis within 2 French Paediatric Cardiac Surgery Centers. The conservative approach, defined by the prolonged use of ventilation until successful weaning from respiratory support, was the primary strategy adopted in both centres. In case of unsuccessful evolution, a diaphragmatic plication was scheduled. Total ventilation time included invasive and non-invasive ventilation. Diaphragm asymmetry was defined by the number of posterior rib segments counted between the 2 hemi-diaphragms on the chest X-ray after cardiac surgery.

RESULTS

Fifty-one neonates and infants were included in the analysis. Patients' median age was 12.0 days at cardiac surgery (5.0-82.0), and median weight was 3.5 kg (2.8-4.9). The conservative approach was successful for 32/51 patients (63%), whereas 19/51 patients (37%) needed diaphragm plication. There was no difference in patients' characteristics between groups. Respiratory support prolonged for 21 days or more and diaphragm asymmetry more than 2 rib segments were independently associated with the failure of the conservative strategy [odds ratio (OR) 6.9 (1.29-37.3); P = 0.024 and OR 6.0 (1.4-24.7); P = 0.013, respectively].

CONCLUSIONS

The conservative approach was successful for 63% of the patients. We identified risk factors associated with the strategy's failure.

Diaphragm Dysfunction After Cardiac Surgery: Reappraisal

OBJECTIVES

The aim of this study was to re-investigate the incidence, risk factors, and outcomes of postoperative diaphragmatic dysfunction (DD) with actual cardiac surgery procedures.

DESIGN

Single-center, retrospective, observational study based on a prospectively collected database.

SETTING

Tertiary care cardiac surgery center.

PARTICIPANTS

Patients who underwent cardiac surgery between January 2016 and September 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The DD group included patients with clinically perceptible diaphragmatic paralysis, which was confirmed by chest ultrasound (amplitude of the diaphragm movement in time-motion mode at rest, after a sniff test). The primary endpoint was the incidence of DD. Among 3,577 patients included, the authors found 272 cases of DD (7.6%). Individuals with DD had more arterial hypertension (64.3% v 52.6%; p < 0.0001), higher body mass index (BMI) (28 [25-30] kg/m²v 26 [24-29] kg/m²; p < 0.0002), and higher incidence of coronary bypass grafting (CABG) (58.8% v 46.6%; p = 0.0001). DD was associated with more postoperative pneumonia (23.9% v 8.7%; p < 0.0001), reintubation (8.8% v 2.9%; p < 0.0001), tracheotomy (3.3% v 0.3%; p < 0.0001), noninvasive ventilation (45.6% v 5.4%; p < 0.0001), duration of mechanical ventilation (five [four-11] hours v four [three-six] hours; p < 0.0001), and intensive care unit and hospital stays (14 [11-17] days v 13 [11-16] days; p < 0.0001). In multivariate analysis, DD was associated with CABG (odds ratio [OR] 1.9 [1.5-2.6]; p = 0.0001), arterial hypertension (OR 1.4 [1.1-1.9]; p = 0.008), and BMI (OR per point 1.04 [1.01-1.07] kg/m²; p = 0.003).

CONCLUSIONS

The incidence of symptomatic DD after cardiac surgery was 7.6%, leading to respiratory complications and increased ICU stay. CABG was the principal factor associated with DD.

Diaphragmatic ultrasound: a review of its methodological aspects and clinical uses

The diaphragm is the main muscle of respiration, acting continuously and uninterruptedly to sustain the task of breathing. Diaphragmatic dysfunction can occur secondary to numerous pathological conditions and is usually underdiagnosed in clinical practice because of its nonspecific presentation. Although several techniques have been used in evaluating diaphragmatic function, the diagnosis of diaphragmatic dysfunction is still problematic. Diaphragmatic ultrasound has gained importance because of its many advantages, including the fact that it is noninvasive, does not expose patients to radiation, is widely available, provides immediate results, is highly accurate, and is repeatable at the bedside. Various authors have described ultrasound techniques to assess diaphragmatic excursion and diaphragm thickening in the zone of apposition. Recent studies have proposed standardization of the methods. This article reviews the usefulness of ultrasound for the evaluation of diaphragmatic function, addressing the details of the technique, the main findings, and the clinical applications.

Lung ultrasound in children: What does it give us?

Lung ultrasound (LUS), a non-invasive non-ionizing radiation tool, has become essential at the bedside in both adults and children, particularly in the critically ill. This manuscript reviews normal LUS patterns and the most important pathologies that LUS allows to diagnose. Normal LUS is represented by the pleural line, the lung-sliding and the A-lines and B-lines. These two last findings are artifacts derived from the pleural line. Pleural effusion appears as an anechoic collection. Pneumothorax is suspected when only A-lines are present, without lung-sliding and B-lines. Alveolo-interstitial syndrome is characterized by different degrees of confluent B-lines and can be present in different pathologies such as pulmonary edema and acute respiratory distress syndrome. The distribution of B-lines helps to differentiate between them. LUS is useful to evaluate the response to lung recruitment in pathologies such as acute respiratory distress syndrome or acute chest syndrome. The distribution of B-lines also appears to be useful to monitor the response to antibiotics in pneumonia. However, further studies are needed to further ascertain this evidence. LUS is also useful to guide thoracocentesis.

Ultrasonographic postoperative evaluation of diaphragm function of patients with congenital heart defects

Background

This study aims to investigate the role of ultrasonography in the postoperative evaluation of diaphragm function in patients with congenital heart defect.

Methods

This prospective study included a total of 360 patients (176 males, 184 females; mean age 2 years; range, 1 month to 8 years) who underwent congenital heart surgery and 44 patients (22 males, 22 females; mean age 1 years; range, 1 month to 4 years) who underwent diaphragm ultrasonography between September 2018 and March 2019. Ultrasonography was performed for the patients who had difficulty in weaning from mechanical ventilation or who were thought to have diaphragm dysfunction due to pathological findings on postoperative chest X-rays. The findings were interpreted as normal, paresis, or paralysis.

Results

Diaphragm dysfunction was demonstrated in 23 patients (6.3%), paralysis in 11 patients (3%), and paresis in 12 patients (3.3%). A median sternotomy was performed in 21 patients (91%), and seven of them (30%) were redo cases. Five patients (21%) had single ventricle physiology. Six patients (1.6%) needed an intervention due to diaphragm dysfunction. The interventional procedures were diaphragm plication in three patients (0.8%) and tracheotomy in three patients (0.8%). Three of these patients had a single ventricle and three had biventricular physiology. The median time after surgery for these procedures was 36 days. One patient (0.2%) died in the intensive care unit. The mean length of stay in the intensive care unit and hospital was 36±12 and 48±21 days, respectively.

Conclusion

Diaphragm dysfunction should be kept in mind in patients undergoing congenital heart surgery and in those who need prolonged intubation during the postoperative period. Ultrasonography is a non-invasive diagnostic tool which can be used to identify diaphragm dysfunction and the best course of management of this clinical condition.

Diaphragmatic paralysis in young children: A literature review

Diaphragmatic paralysis (DP) is a rare cause of respiratory distress in young children. In the first years of life, the main cause is phrenic nerve injury after cardiothoracic surgery or obstetrical trauma. DP usually presents as respiratory distress. Asymmetrical thorax elevation, difficulty weaning from mechanical ventilation, pulmonary atelectasis, and repeated pulmonary infections are other suggestive signs or complications. DP is usually suspected on chest X-ray showing abnormal hemidiaphragm elevation. Although fluoroscopy was considered the gold standard for DP confirmation, it has gradually been replaced by ultrasound, which can be done at the bedside. Some electrophysiological tools may be useful for a better characterization of phrenic nerve injury and chance of recovery. The management of DP is mainly based on clinical severity. In mild asymptomatic cases, DP may only require close monitoring. In more severe cases, adequate ventilatory support and/or surgical diaphragmatic plication may be needed. Electrophysiological tools may help clinicians assess the ideal timing for diaphragmatic plication.

Diagnostic Value of Ultrasound in Detecting Causes of Pediatric Chest X-Ray Opacity

OBJECTIVES

Computed tomography is considered as the diagnostic gold standard for following up the majority of pediatric chest X-ray (CXR) opacities. However, radiation, cost, and waiting times have led to search for diagnostic alternatives. This study was conducted to determine the diagnostic accuracy of the ultrasound (US) in detecting the causes of pediatric CXR opacities.

MATERIALS AND METHODS

This study was conducted on the pediatric patients with CXR opacity referring to Dr. Sheikh Hospital in Mashhad, Iran during 2016-2017. After undergoing the US exam, the patients were followed to obtain the final diagnosis based on reference standard (RF). The accuracy of the US was calculated in detection of thoracic lesions. P value <0.05 was considered to be significant.

RESULTS

The most common diagnostic cause of CXR opacity based on RF was pneumonia (n=46, 35-38%), thymus (n=37, 28-46%), bone and soft tissue mass (n=12, 9.23%), cystic lesions (n=11, 8.46%), and diaphragmatic lesions (n=10, 7.69%), as well as intrathoracic masses and empyema (n=7, 5.38%). In only four patients (3.07%), the final diagnosis based on RF was inconsistent with the US diagnosis. The diagnostic accuracy of the US was 100% in the diagnosis of bone and soft tissue masses, diaphragmatic lesions, empyema, and normal thymus, and the accuracy was 96.92% for pneumonia, and 99.23% for cystic lesions and intrathoracic masses.

CONCLUSION

Regarding the assessed diagnostic accuracy, the US can be a reliable diagnostic tool to differentiate the main cause of pediatric CXR opacity.

Body Position Affects Ultrasonographic Measurement of Diaphragm Contractility

PURPOSE

(1) Determine whether ultrasonography can detect differences in diaphragm contractility between body positions. (2) Perform reliability analysis of diaphragm thickness measurements in each test condition.

METHODS

We used a repeated-measures experimental design with 45 healthy adults where 3 B-mode ultrasound images were collected at peak-inspiration and end-expiration in supine, sitting, and standing. Mean diaphragm thickening fractions were calculated for each test position. Statistical significance was tested using 1-way repeated-measures analysis of variance with planned comparisons. For reliability analysis, the intraclass correlation coefficient (3, 3) was calculated.

RESULTS

Mean diaphragm thickening fraction increased from 60.2% (95% confidence interval [CI] 53.0%, 67.9%) in supine, to 96.5% (95% CI 83.2%, 109.9%) while seated and to 173.8% (95% CI 150.5%, 197.1%) while standing. Body position was a significant factor overall (P < .001), as were comparisons between each individual position (P < .001). Intraobserver reliability was excellent (>0.93) for all body positions tested.

CONCLUSIONS

Ultrasound imaging detected positional differences in diaphragm contractility. The effect of gravitational loading on diaphragm length-tension, and body position-mediated changes in intra-abdominal pressure may explain the differences found. Future research should address methodological concerns and apply this method to patients participating in early mobilization programs in the intensive care unit.

Point of care diaphragm ultrasound in infants with bronchiolitis: A prospective study

BACKGROUND

Bronchiolitis is the most common reason for hospitalization of children worldwide. Many scoring systems have been developed to quantify respiratory distress and predict outcome, but none of them have been validated. We hypothesized that the ultrasound evaluation of the diaphragm could quantify respiratory distress and therefore we correlated the ultrasound diaphragm parameters with outcome.

METHODS

Prospective study of infants with bronchiolitis (1-12 months) evaluated in a pediatric emergency department. Ultrasonography examinations of the diaphragm was performed (diaphragm excursion [DE], inspiratory excursion [IS], inspiratory/expiratory relationship [I/E], and thickness at end-expiration [TEE] and at end-inspiration [TEI]; thickening fraction [TF]).

RESULTS

We evaluated 61 infants, 50.8 % males. Mean TF was 47% (IQR 28.6-64.7), mean I/E 0.47 (± 0.15), mean DE 10.39 ± 4 mm. There was a linear correlation between TF and oxygen saturation at first evaluation (P = 0.006, r = 0.392). All children with lower values of TF required HFNC and one of them required CPAP. A higher IS was associated with the future need of respiratory support during admission (P = 0.007). IS correlated with the hours of oxygen delivery needed (P = 0.032, r = 0.422). TEI (t = 3.701, P = 0.002) was found to be main predictor of hours of oxygen delivery needed.

CONCLUSION

This study described ultrasound diaphragmatic values of previously healthy infants with bronchiolitis. DE, IS, and TEI correlated with outcome. If confirmed in larger studies, bedside ultrasound semiology of the diaphragm can be a new objective tool for the evaluation and outcome prediction of infants with bronchiolitis.

Can Diaphragm Dysfunction Be Reliably Evaluated with Pocket-Sized Ultrasound Devices in Intensive Care Unit?

Background

Diaphragm dysfunction (DD) is frequently seen in critically ill patients, and ultrasound could be a useful tool to detect it and to predict extubation success or failure in mechanically ventilated patients. Besides, it would also be useful in differential diagnosis of dyspnea and respiratory failure. The aim of this study is to evaluate usefulness and accuracy of pocket-sized ultrasound devices (PSDs) in assessment of DD in intensive care unit (ICU) patients in comparison with standard ultrasound devices (SD).

Methods

In this prospective observational study, we compared the performance of PSD and SD in visualization of diaphragm, detection of paradoxical movement, measurement of tidal and maximal thickness, tidal and maximal excursion, and calculation of thickening fraction (TF) of the diaphragm. We used Bland and Altman test for agreement and bias analysis and intraclass correlation analysis to evaluate interobserver variability.

Results

Thirty-nine patients were included in the study. In 93% of the patients, diaphragm was visualized with PSD. There was very good agreement between the measurements of the devices, and there was no proportional bias in the measurements of tidal inspiratory and expiratory thickness, tidal TF, tidal excursion, and maximal inspiratory thickness. In interobserver reliability analysis of all measurements for both devices, ICC coefficients were higher than 0.8. Total diaphragm examination times of the devices were similar (p > 0.05).

Conclusion

These results suggest that PSD can be useful in ICU patients for evaluating DD. But further studies are required to determine the exact place of these devices in evaluation of DD in ICU patients.

Mechanical birth-related trauma to the neonate: An imaging perspective

Mechanical birth-related injuries to the neonate are declining in incidence with advances in prenatal diagnosis and care. These injuries, however, continue to represent an important source of morbidity and mortality in the affected patient population. In the United States, these injuries are estimated to occur among 2.6% of births. Although more usual in context of existing feto-maternal risk factors, their occurrence can be unpredictable. While often superficial and temporary, functional and cosmetic sequelae, disability or even death can result as a consequence of birth-related injuries. The Agency for Healthcare research and quality (AHRQ) in the USA has developed, through expert consensus, patient safety indicators which include seven types of birth-related injuries including subdural and intracerebral hemorrhage, epicranial subaponeurotic hemorrhage, skeletal injuries, injuries to spine and spinal cord, peripheral and cranial nerve injuries and other types of specified and non-specified birth trauma. Understandably, birth-related injuries are a source of great concern for the parents and clinician. Many of these injuries have imaging manifestations. This article seeks to familiarize the reader with the clinical spectrum, significance and multimodality imaging appearances of neonatal multi-organ birth-related trauma and its sequelae, where applicable.

Teaching points

• Mechanical trauma related to birth usually occurs with pre-existing feto-maternal risk factors.

• Several organ systems can be affected; neurologic, musculoskeletal or visceral injuries can occur.

• Injuries can be mild and transient or disabling, even life-threatening.

• Imaging plays an important role in injury identification and triage of affected neonates.

Point-of-care ultrasound in pediatric anesthesiology and critical care medicine

Ultrasound has increasingly become a clinical asset in the hands of the anesthesiologist and intensivist who cares for children. Though many applications for ultrasound parallel adult modalities, children as always are not simply small adults and benefit from the application of ultrasound to their management in various ways. Body composition and size are important factors that affect ultrasound performance in the child, as are the pathologies that may uniquely afflict children and aspects of procedures unique to this patient population. Ultrasound simplifies vascular access and other procedures by visualizing structures smaller than those in adults. Maturation of the thoracic cage presents challenges for the clinician performing pulmonary ultrasound though a greater proportion of the thorax can be seen. Moreover, ultrasound may provide unique solutions to sizing the airway and assessing it for cricothyroidotomy. Though cardiac ultrasound and neurosonology have historically been performed by well-developed diagnostic imaging services, emerging literature stresses the utility of clinician ultrasound in screening for pathology and providing serial observations for monitoring clinical status. Use of ultrasound is growing in clinical areas where time and diagnostic accuracy are crucial. Implementation of ultrasound at the bedside will require institutional support of education and credentialing. It is only natural that the pediatric anesthesiologist and intensivist will lead the incorporation of ultrasound in the future practice of these specialties.

[Exploring the diaphragm: Ultrasound is essential]

The diaphragm is the muscle most implicated in breathing. Its morphological exploration usually depends on pulmonary radiography, fluoroscopy, CT-scanning and MRI. Its function is evaluated by the classical respiratory functional tests, the measurement of maximum inspiratory and expiratory pressures, the transdiaphragmatic pressure and even an electromyogram. Ultrasound is a technique still insufficiently used in respiratory medicine. It offers, however, many advantages: it is easy to implement, there is no irradiation, it is usable at the bedside, particularly when the patient is immobile or in intensive care. The results of the examination are immediately available. It allows morphological and dynamic study of each hemidiaphragm as well as providing invaluable information on the thoracic and subdiaphragmatic environment. Its field of exploration is extremely wide: raised hemidiaphragm, dyspnea following a stroke or a surgical procedure (thoracic or abdominal), road accident trauma, diagnosis and follow-up of a paresis or paralysis, evaluation of diaphragmatic mobility during the course of COPD (Chronic Obstructive Pulmonary Disease) and many other pathologies. Ultrasound is insufficiently used in pleural disease and even less so in the evaluation of the morphology and function of the diaphragm.

Ultrasound for diaphragmatic dysfunction in postoperative cardiac children

Introduction The use of ultrasound for assessing diaphragmatic dysfunction after paediatric cardiac surgery may be under-utilised. This study aimed to evaluate the role of bedside ultrasound performed by an intensivist to diagnose diaphragmatic dysfunction and the need for plication after paediatric cardiac surgery.

METHODS

We carried out a retrospective cohort study on prospectively collected data of postoperative children admitted to the paediatric cardiac ICU during 2013. Diaphragmatic dysfunction was suspected based on difficulties in weaning from positive pressure ventilation or chest X-ray findings. Ultrasound studies were performed by the paediatric cardiac ICU intensivist and confirmed by a qualified radiologist.

RESULTS

Out of 344 postoperative patients, 32 needed diaphragm ultrasound for suspected dysfunction. Ultrasound studies confirmed diaphragmatic dysfunction in 17/32 (53%) patients with an average age and weight of 10.8±3.8 months and 6±1 kg, respectively. The incidence rate of diaphragmatic dysfunction was 4.9% in relation to the whole population. Diaphragmatic plication was needed in 9/17 cases (53%), with a rate of 2.6% in postoperative cardiac children. The mean plication time was 15.1±1.3 days after surgery. All patients who underwent plication were under 4 months of age. After plication, they were discharged with mean paediatric cardiac ICU and hospital stay of 19±3.5 and 42±8 days, respectively.

CONCLUSIONS

Critical-care ultrasound assessment of diaphragmatic movement is a useful and practical bedside tool that can be performed by a trained paediatric cardiac ICU intensivist. It may help in the early detection and management of diaphragmatic dysfunction after paediatric cardiac surgery through a decision-making algorithm that may have potential positive effects on morbidity and outcome.

Bedside Ultrasound for the Diagnosis of Abnormal Diaphragmatic Motion in Children After Heart Surgery

OBJECTIVE

To assess the utility of bedside ultrasound combining B- and M-mode in the diagnosis of abnormal diaphragmatic motion in children after heart surgery.

DESIGN

Prospective post hoc blinded comparison of ultrasound performed by two different intensivists and fluoroscopy results with electromyography.

SETTING

Tertiary university hospital.

SUBJECTS

Children with suspected abnormal diaphragmatic motion after heart surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Abnormal diaphragmatic motion was suspected in 26 children. Electromyography confirmed the diagnosis in 20 of 24 children (83.3%). The overall occurrence rate of abnormal diaphragmatic motion during the study period was 7.5%. Median patient age was 5 months (range, 16 d to 14 yr). Sensitivity and specificity of chest ultrasound performed at the bedside by the two intensivists (91% and 92% and 92% and 95%, respectively) were higher than those obtained by fluoroscopy (87% and 83%). Interobserver agreement (k) between both intensivists was 0.957 (95% CI, 0.87-100).

CONCLUSIONS

Chest ultrasound performed by intensivists is a valid tool for the diagnosis of diaphragmatic paralysis, presenting greater sensitivity and specificity than fluoroscopy. Chest ultrasound should be routinely used after pediatric heart surgery given its reliability, reproducibility, availability, and safety.

Assessment of diaphragmatic dysfunction in the critically ill patient with ultrasound: a systematic review

PURPOSE

Diaphragmatic dysfunction (DD) has a high incidence in critically ill patients and is an under-recognized cause of respiratory failure and prolonged weaning from mechanical ventilation. Among different methods to assess diaphragmatic function, diaphragm ultrasonography (DU) is noninvasive, rapid, and easy to perform at the bedside. We systematically reviewed the current literature assessing the usefulness and accuracy of DU in intensive care unit (ICU) patients.

METHODS

Pubmed, Cochrane Database of Systematic Reviews, Embase, Scopus, and Google Scholar Databases were searched for pertinent studies. We included all original, peer-reviewed studies about the use of DU in ICU patients.

RESULTS

Twenty studies including 875 patients were included in the final analysis. DU was performed with different techniques to measure diaphragmatic inspiratory excursion, thickness of diaphragm (Tdi), and thickening fraction (TF). DU is feasible, highly reproducible, and allows one to detect diaphragmatic dysfunction in critically ill patients. During weaning from mechanical ventilation and spontaneous breathing trials, both diaphragmatic excursion and diaphragmatic thickening measurements have been used to predict extubation success or failure. Optimal cutoffs ranged from 10 to 14 mm for excursion and 30-36 % for thickening fraction. During assisted mechanical ventilation, diaphragmatic thickening has been found to be an accurate index of respiratory muscles workload. Observational studies suggest DU as a reliable method to assess diaphragm atrophy in patients undergoing mechanical ventilation.

CONCLUSIONS

Current literature suggests that DU could be a useful and accurate tool to detect diaphragmatic dysfunction in critically ill patients, to predict extubation success or failure, to monitor respiratory workload, and to assess atrophy in patients who are mechanically ventilated.

Bilateral diaphragmatic palsy after congenital heart surgery: management options

Diaphragmatic paralysis following phrenic nerve injury is a major complication following congenital cardiac surgery. In contrast to unilateral paralysis, patients with bilateral diaphragmatic paralysis present a higher risk group, require different management methods, and have poorer prognosis. We retrospectively analysed seven patients who had bilateral diaphragmatic paralysis following congenital heart surgery during the period from July, 2006 to July, 2014. Considerations were given to the time to diagnosis of diaphragm paralysis, total ventilator days, interval after plication, and lengths of ICU and hospital stays. The incidence of bilateral diaphragmatic paralysis was 0.68% with a median age of 2 months (0.6-12 months). There was one neonate and six infants with a median weight of 4 kg (3-7 kg); five patients underwent unilateral plication of the paradoxical diaphragm following recovery of the other side, whereas the remaining two patients who did not demonstrate a paradoxical movement were successfully weaned from the ventilator following recovery of function in one of the diaphragms. The median ventilation time for the whole group was 48 days (20-90 days). The median length of ICU stay was 46 days (24-110 days), and the median length of hospital stay was 50 days (30-116 days). None of the patients required tracheostomy for respiratory support and there were no mortalities, although all the patients except one developed ventilator-associated pneumonia. The outcome of different management options for bilateral diaphragmatic paralysis following surgery for CHD is discussed.

Establishing intensivist-driven ultrasound at the PICU bedside--it's about time*

OBJECTIVE

To discuss pediatric intensivist-driven ultrasound and the exigent need for research and practice definitions pertaining to its implementation within pediatric critical care, specifically addressing issues in ultrasound-guided vascular access and intensivist-driven echocardiography.

CONCLUSIONS

Intensivist-driven ultrasound improves procedure safety and reduces time to diagnosis in clinical ultrasound applications, as demonstrated primarily in adult patients. Translating these applications to the PICU requires thoughtful integration of the technology into practice and would best be informed by dedicated ultrasound research in critically ill children.

Variability in diaphragm motion during normal breathing, assessed with B-mode ultrasound

STUDY DESIGN

Clinical measurement, cross-sectional.

OBJECTIVES

To establish a set of normal values for diaphragm thickening with tidal breathing in healthy subjects.

BACKGROUND

Normal values for diaphragm contractility, as imaged sonographically, have not been described, despite the known role of the diaphragm in contributing to spinal stability. If the normal range of diaphragm contractility can be defined in a reliable manner, ultrasound has the potential to be used clinically and in research as a biofeedback tool to enhance diaphragm activation/contractility.

METHODS

B-mode ultrasound was performed on 150 healthy subjects to visualize and measure hemi-diaphragm thickness on each side at resting inspiration and expiration. Primary outcome measures were hemi-diaphragm thickness and thickening ratio, stratified for age, gender, and body mass index. Interrater and intrarater reliability were also measured.

RESULTS

Normal thickness of the diaphragm at rest ranged from 0.12 to 1.18 cm, with slightly greater thickness in men but no effect of age. Average ± SD change in thickness from resting expiration to resting inspiration was 20.0% ± 15.5% on the right and 23.5% ± 24.4% on the left; however, almost one third of healthy subjects had no to minimal diaphragm thickening with tidal breathing.

CONCLUSION

There is wide variability in the degree of diaphragm contractility during quiet breathing. B-mode ultrasound appears to be a reliable means of determining the contractility of the diaphragm, an important muscle in spinal stability. Further studies are needed to validate this imaging modality as a clinical tool in the neuromuscular re-education of the diaphragm to improve spinal stability in both healthy subjects and in patients with low back pain.

Neuromuscular ultrasound for evaluation of the diaphragm

Neuromuscular clinicians are often asked to evaluate the diaphragm for diagnostic and prognostic purposes. Traditionally, this evaluation is accomplished through history, physical exam, fluoroscopic sniff test, nerve conduction studies, and electromyography (EMG). Nerve conduction studies and EMG in this setting are challenging, uncomfortable, and can cause serious complications, such as pneumothorax. Neuromuscular ultrasound has emerged as a non-invasive technique that can be used in the structural and functional assessment of the diaphragm. In this study we review different techniques for assessing the diaphragm using neuromuscular ultrasound and the application of these techniques to enhance diagnosis and prognosis by neuromuscular clinicians.

Diaphragmatic Nerve Palsy After Cardiac Surgery in Children in Egypt

Introduction: Diaphragmatic paralysis (DP) due to phrenic nerve injury is a complication which occurs in association with congenital cardiac surgery and may be a life-threatening event in infants and young children. Information about this complication is still scarce from the developing countries. Methods: Retrospective study evaluated the incidence of DP among 414 patients who underwent congenital cardiac surgery in Abo Elriesh Children’s Specialized Hospital, Cairo University, Egypt, in the duration from April 2009 to December 2011. Results: Incidence of DP was 3.6% (15 of 414 cases). Median age of affected patients was 10 months (ranged from 1 month to 13 years). Diagnosis of DP was observed after ventricular septal defect repair (3.9%), Glenn anastomosis (8.6%), Tetralogy of Fallot repair (4.3%), Senning operation (10%), arterial switch operation (3.2%), Fontan procedure (33%), coarctation of the aorta repair (7%), and pulmonary artery banding (6.4%). Diaphragmatic plication was performed in 4 of 15 cases. Patients with DP had significantly prolonged mechanical ventilation duration as compared to unaffected patients (median 120, range 48-600 vs 4, range 0-48 hours, P < .000). They also had a higher incidence of nosocomial pneumonia in 8 of 15 (53%) cases, longer duration of intensive care unit stay (median 15, range 4-62 days, P < .006), and significant mortality in 7 of 15 (46%; P < .004). Mortality among patients who underwent diaphragm plication was 1 of 4 (25%). Conclusion: Diaphragmatic paralysis is a relatively rare complication of congenital cardiac surgery in children. Its occurrence is associated with increased morbidity and mortality. A high index of clinical suspicion, utilization of bedside diagnostic tools, and a policy of early plication for certain patients may lead to improved outcomes.