Diaphragm Ultrasound for Assessing Diaphragmatic Function and Predicting Ventilator Weaning Success: A Review of the Literature

Background: In the treatment of critically ill children, mechanical ventilation (MV) is a crucial life support method, with weaning being a key process. Currently, predicting successful weaning in mechanically ventilated children presents numerous challenges. Traditional predictors have notable shortcomings, including instability of specificity, inconsistency of thresholds, and limited clinical applicability. There is an urgent need for more accurate and reliable methods to predict weaning to prevent ventilator-related lung injury and ventilator-induced diaphragmatic dysfunction (VIDD) in children due to improper weaning. Objectives: This study aims to assess the prognostic value of diaphragmatic ultrasound parameters in predicting successful weaning outcomes in pediatric patients undergoing MV, compared to healthy controls. Patients and Methods: This was a retrospective case-control study. Sixty critically ill pediatric patients undergoing MV in our hospital's Pediatric Intensive Care Unit (PICU) were included in the study as the observation group (MV group), which was subdivided into a successful weaning group (39 cases) and a failed weaning group (21 cases) based on clinical weaning outcomes. Additionally, forty age-, gender-, and Body Mass Index (BMI)-matched healthy children undergoing routine health examinations were selected as the control group. Diaphragmatic ultrasound parameters measured included diaphragmatic excursion (DE), diaphragmatic end-inspiratory thickness (Tei), diaphragmatic end-expiratory thickness (Tee), diaphragmatic thickening fraction (DTF), diaphragmatic excursion to rapid shallow breathing index (DE-RSBI), and diaphragmatic thickening fraction to rapid shallow breathing index (DTF-RSBI). The changes in diaphragmatic function in MV patients were assessed by comparing these parameters between the control and MV groups. Furthermore, the diaphragmatic ultrasound parameters between the successful and failed weaning groups were compared, and the predictive accuracy for weaning outcomes was assessed through receiver operating characteristic (ROC) curve analysis, determining the area under the curve (AUC), sensitivity, and specificity. Results: (1) The control group exhibited significantly higher DE, Tei, Tee, and DTF values compared to the MV group, while DE-RSBI and DTF-RSBI were significantly lower, indicating statistically significant differences (P < 0.05). (2) The failed weaning group had longer durations of MV and total hospital stays compared to the successful weaning group (P < 0.05); the successful weaning group exhibited higher DE and DTF, and lower DE-RSBI and DTF-RSBI than the failed weaning group (P < 0.05). (3) ROC curve analysis revealed that the AUCs for DE, DE-RSBI, DTF, and DTF-RSBI in predicting weaning outcomes were 0.882, 0.810, 0.723, and 0.725, respectively, suggesting their value in guiding clinical weaning decisions. Conclusion: Diaphragmatic ultrasound provides an effective method for assessing diaphragmatic function in pediatric patients on MV and offers a valuable reference for clinicians in making weaning decisions.

BackgroundWith the increased ageing of society, more and more elderly people are admitted to the intensive care unit, How to accurately predict whether elderly patients can successfully wean from the ventilator is more complicated. Diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF) were measured by bedside ultrasound to assess diaphragm function. The lung ultrasound score (LUS) and the rapid shallow breathing index (RBSI) were used as indices of diaphragm function to predict the outcome of weaning from mechanical ventilation. The aim of this study was to examine the clinical utility of these parameters in predicting extubation success.MethodsThis prospective study included 101 consecutive elderly patients undergoing a trial of extubation in the ICU of Haidian Hospital between June 2017 and July 2020. Patients were divided into the successful weaning group (n = 69) and the failed weaning group (n = 32). Baseline characteristics, including RSBI, were recorded. Measurements of DE, DTF and LUS were made using ultrasound within 24 h before extubation.ResultsMedian DE was greater in patients with extubation success than in those with extubation failure (1.64 cm vs. 0.78 cm, p = 0.001). Patients with extubation success had a greater DTF than those with extubation failure (49.48% vs. 27.85%, p = 0.001). The areas under the receiver operating curves for the RSBI, LUS, DE and DFT were 0.680, 0.764, 0.831 and 0.881, respectively. The best cut-off values for predicting successful weaning were DTF ≥ 30%, DE ≥ 1.3 cm, LUS ≤ 11, and RSBI ≤ 102. The specificity of DTF (84%) in predicting weaning outcome was higher than that of RBSI (53%), that of LUS (55%), and that of DE (62%). The sensitivity of DTF (94%) was greater than that of RBSI (85%), that of LUS (71%), and that of DE (65%). The combination of RSBI, LUS, DE, and DTF showed the highest AUC (AUC = 0.919), with a sensitivity of 96% and a specificity of 89%.ConclusionsDTF has higher sensitivity and specificity for the prediction of successful weaning in elderly patients than the other parameters examined. The combination of RSBI, LUS, DE and DFT performed well in predicting weaning outcome. This has potentially important clinical application and merits further evaluation.

HighlightsWhat are the main findings?•Diaphragmatic excursion increases during the first 48 h in healthy neonates.•On day two, TTN infants show lower diaphragmatic excursion compared with controls, and a negative correlation develops between excursion and LUS, indicating impaired diaphragmatic function in the context of lung disease.What are the implications of the main findings?•Diaphragmatic ultrasound may help identify early functional impairment in neonates with TTN, complementing lung ultrasound to characterize disease severity.•Integrated lung–diaphragm ultrasound assessment may support monitoring of disease progression and guide decisions on respiratory support, especially during the first 48 h of life.Background: The role of diaphragmatic function in transient tachypnea of the newborn (TTN) remains poorly understood. This study aimed to compare diaphragmatic ultrasound parameters between neonates with TTN requiring non-invasive ventilation (NIV) and healthy neonates. Secondary objectives include the relationships between these parameters and gestational age (GA), birth weight (BW), and the evaluation of inter-operator reproducibility. Methods: This prospective observational pilot study involved neonates with GA ≥ 34 weeks with clinical and ultrasound diagnosis of TTN treated with NIV. An equal number of healthy neonates served as controls. Diaphragmatic and lung ultrasound were performed on day 1 (T0) and day 2 (T1) of life. Measurements included end-inspiratory and end-expiratory diaphragmatic thickness (DTi and DTe, respectively), diaphragmatic excursion (DE), and Lung Ultrasound Score (LUS). Inter-operator reproducibility was tested in 31 neonates (62 scans in total). Results: Forty neonates were enrolled (20 TTN, 20 controls). DE was significantly higher in controls compared with TTN neonates (4.6 ± 0.9 mm vs. 5.4 ± 1.3 mm, p = 0.03) and increased from T0 to T1 in the control group (4.6 ± 1.1 mm vs. 5.4 ± 1.3 mm, p = 0.04), while no significant variation was observed in TTN cases. A negative correlation, approaching significance, was found between DE and LUS at T1 (p = 0.05). DTi and DTe increased linearly with GA and BW (p < 0.001). Bland–Altman analysis showed low bias and acceptable limits of agreement between measurements. Conclusions: The underlying pulmonary disease may influence diaphragmatic function in neonates with TTN. The integration of lung and diaphragmatic ultrasound could be useful for monitoring disease progression and follow-up.

Background:Successful weaning is a crucial element in care toward critically ill patients on mechanical ventilation. An attempt was made to propose and assess a reliable predictor of weaning outcome.Materials and Methods:A prospective observational study was conducted on 76 patients on mechanical ventilation, assessed by Acute Physiology and Chronic Health Evaluation II (APACHE II) score. For all these patients we calculate Rapid shallow breathing index (RSBI), Ultrasonographic diaphragmatic parameters namely diaphragmatic excursion (DEx), diaphragmatic thickening fraction (DTF) and diaphragmatic contraction velocity (DCV). Values were compared among patients with two groups of successful and failed weaning outcomes, respectively, and statistically analyzed.Results:Of 76 patients included in the study, with ultrasonographic diaphragmatic parameters being measured 30 min into SBT, 71 patients tolerated spontaneous breathing test (SBT) for 2 h and were extubated. Of these, 61 patients did not require reintubation or any form of ventilatory support within 48 h after extubation. There was a statistically significant difference in APACHE II scores, duration of ventilation, oxygen saturation levels, RSBI, DEx, DTF, and DCV between groups of patients who showed successful and failed weaning from mechanical ventilation. There were a significant positive correlation between the duration of ventilation and the RSBI and a significant negative correlation between DEx, DCV, DTF, and duration of ventilation. As predictors of weaning outcome, RSBI showed the best validity, followed by DCV, DTF, and DEx.Conclusion:RSBI can be reliably used as a predictor of weaning outcome in critically ill patients on mechanical ventilation.

Ventilator weaning is the process of discontinuing mechanical ventilation from patients with respiratory failure. Previous investigations reported that 39%-40% of the intensive care unit (ICU) patients need mechanical ventilator for sustaining their lives. Among them, 90% of the patients can be weaned from the ventilator in several days while other 5%-15% of the patients need longer ventilator support. Modern mechanical ventilators are believed to be invaluable tools for stabilizing the condition of patients in respiratory failure. However, ventilator support should be withdrawn promptly when no longer necessary so as to reduce the likelihood of known nosocomial complications and costs. Although successful ventilator weaning of ICU patients has been widely studied, indicators for accurate prediction are still under investigation. Furthermore, the predication rate of successful weaning is only 35-60% based on previous studies. It is desirable to have objective measurements and predictors of weaning that decrease the dependence on the wisdom and skill of an individual physician. However, one study showed that clinicians were often wrong when predicting weaning outcome. In this study, 189 patients, who had been supported by mechanical ventilation for longer than 21 days and were clinically stable were recruited from our all-purpose ICUs. Twenty-seven variables in total were recorded, while only 8 variables which reached significant level were used for support vector machine (SVM) classification after logistic regression analysis. The result shows that the successful prediction rate achieves as high as 81.5% which outperforms a recently published predictor (78.6%) using combination of sample entropy of three variables, inspiratory tidal volume, expiratory tidal volume, and respiration rate.

BackgroundWeaning from mechanical ventilation is one of the most common challenges in the intensive care unit (ICU). Most of predictive indices of weaning from mechanical ventilation are often inaccurate. This study was performed to assess the accuracy of diaphragmatic ultrasonography for predicting weaning outcome in mechanically ventilated patients with sepsis in ICU.ResultsSixty patients with sepsis in medical ICU were prospectively enrolled. All patients were ventilated in pressure support. Patients underwent a spontaneous breathing trial (SBT) on T-piece when they met all the following criteria: FiO2 < 0.6, PEEP ≤5 cmH2O, PaO2/FiO2 > 200, respiratory rate <30 breaths per minute, absence of fever, alert and cooperative, hemodynamic stability without or with low-dose vasoactive therapy support, and rapid shallow breathing index (RSBI)<105. During the trial, the patient was instructed to perform deep breathing to total lung capacity (TLC) and then exhaling to residual volume (RV) and the diaphragm was visualized in the 8th or 9th intercostal space between anterior and mid-axillary lines using a 3–5-MHz curved ultrasound probe to measure diaphragmatic excursion (DE) and a 7–11-MHz linear ultrasound probe to measure diaphragmatic thickness (DT) at TLC and RV, and the diaphragmatic thickness fraction (DTF) was calculated as percentage from the following formula (thickness at end inspiration—thickness at end expiration)/thickness at end expiration. According to weaning outcome, patients were divided into 2 groups: successful weaning group and weaning failure group. Weaning failure was defined as the inability to maintain spontaneous breathing for at least 48 h, without any form of ventilatory support.In the present study, right DTF of more than 37% and DE during deep breathing of more than 6.1 and 5.4 cm on the Rt and Lt side, respectively, were associated with successful weaning from MV. In the study, the sensitivities for right and left DE and DTF were 58.33, 62.5, and 58.33%, respectively, and the pooled specificities were 83.33, 83.33, and 100%, respectively, with p value = 0.032, 0.028, and 0.001, respectively. The area under curve (AUC) for Rt, Lt DE, and DTF were 0.701, 0.712, and 0.840, respectively. The present data indicate a satisfactory diagnostic accuracy in predicting extubation outcome.ConclusionsUltrasonography-based determination of diaphragm function by assessing DTF and DE can be used as predictor of weaning outcome in mechanically ventilated patients with sepsis.

Ventilator weaning is the process of discontinuing mechanical ventilation from patients with respiratory failure. Ventilator support should be withdrawn as soon as possible when it is no longer necessary in order to reduce the likelihood of known nosocomial complications and costs. Previous investigation indicated that clinicians were often wrong when predicting weaning outcome. The motivation of this study is that although successful ventilator weaning of ICU patients has been widely studied, indicators for accurate prediction are still under investigation. The goal of this study is to find a prediction model for successful ventilator weaning using variables such physiological variables, clinical syndromes, demographic variables, and other useful information. The data obtained from 231 patients who had been supported by mechanical ventilator for longer than 21 days within the period from Nov. 2002 to Dec. 2005 were studied retrospectively. Among them, 188 patients were recruited from the period within Nov. 2002 to Dec. 2004 and the other 43 patients from Jan. 2004 to Dec. 2005. All the patients were clinically stable before being considered to undergo a weaning trial. Twenty-seven variables in total were collected with only 6 variables reaching significant level (p<0.05) were used for support vector machine (SVM) classification after statistical analysis. The results show that the constructed model is valuable in assisting clinical doctors to decide if a patient is ready to wean from the ventilator with the sensitivity, specificity, and accuracy as high as 94.74%, 95.83%, and 95.35%, respectively. Further prospective bed side test is needed to verify the efficacy of the model.

DEVELOPMENT AND VALIDATION OF A CLINICAL DECISION-SUPPORT TOOL FOR PREDICTION OF WEANING OUTCOME ON ADMISSION TO THE ICU

Speckle tracking ultrasound is a novel technique for evaluating diaphragm movement, yet its guidance in weaning mechanically ventilated patients remains unclear. In this study, we assessed diaphragmatic function using speckle tracking ultrasound and guided the weaning process. A total of 86 mechanically ventilated patients were included and divided into successful or failed weaning groups. Diaphragmatic function was assessed using speckle tracking ultrasound, M-ultrasound diaphragm excursion (DE), and diaphragmatic twitch force (DTF) after 30 min spontaneous breathing trial (SBT). The diagnostic performance of these indicator in predicting weaning outcomes was also evaluated. In this study, a total of 86 patients completed the follow-up for weaning outcomes, with 35 cases of weaning failure and 51 cases of successful weaning. Logistic regression analysis identified whole strain (p = 0.037) and DE (p = 0.004) as independent predictors of weaning outcome. Receiver operating characteristic (ROC) curve showed that the strain threshold for Costal Diaphragm (Dlcos) was -9.836, Area Under the Curve (AUC) value was 0.760, the predictive specificity for weaning failure was 72.5%, and the sensitivity was 80%. DE value exceeding 1.015 cm had an AUC value of 0.785, noting that DE value had a high specificity (90.2%) for predicting successful weaning, but a lower sensitivity (60%). After merging, the AUC of whole strain and DE was 0.856, and the sensitivity (80%) and specificity (80.4%) were more balanced compared to using DE alone. The findings of this study demonstrate the feasibility of using speckle tracking ultrasound to assess diaphragmatic function in mechanically ventilated patients. The combined utilization of whole strain and DE provides a more precise evaluation of diaphragmatic function in ICU patient, which may improve patient outcome.

Rates of oxygen and ventilator weaning, and factors related to successful weaning in inpatient pediatric pulmonary programs for infants and young children, have not been frequently reported in the literature. A retrospective review was conducted of 34 infants and toddlers with either a diagnostic condition of prematurity (PM) or congenital anomalies/neuromuscular disease (CA/NM) discharged from an inpatient pulmonary program. These cases represent 67 hospital admission-discharge episodes over a 6-year period. The rate of successful oxygen weaning (decrease to 0 hr per day) and ventilator weaning (decrease to <12 hr per day) and predictive factors related to successful ventilator weaning per admission-discharge episode were examined. Successful oxygen weaning was achieved during 24% and successful ventilator weaning was achieved during 30% of the admission-discharge episodes. No significant relationships were found between the selected demographic and clinical factors and oxygen weaning. Using a logistic regression model, the major variable associated with successful ventilator weaning per admission-discharge episode was diagnostic condition. Age at admission and the presence of comorbidities added slightly to the prediction model. The overall model yielded 86% accuracy for predicting a decrease in ventilator hours. However, projecting in which episodes children will not be weaned (negative predictive value = 88.9%) was more accurate than projecting in which episodes children will be weaned (positive predictive value = 73.3%). Although the program achieved a relatively low rate of successful ventilator weaning, children with a diagnostic condition of prematurity were more likely to be successfully weaned during inpatient pulmonary rehabilitation.

The aim of this study is to examine the diagnostic significance of using handgrip dynamometry and diaphragmatic ultrasound in intensive care unit-acquired weakness (ICU-AW). This study included patients who received mechanical ventilation in the ICU at the Fourth Hospital of Hebei Medical University from July to December 2020. We collected comprehensive demographic data and selected conscious patients for muscle strength and ICU-AW assessments. The evaluation comprised grip strength measurement and bedside ultrasound for diaphragmatic excursion (DE) and thickening fraction (DTF). Results were documented for comparative analysis between patient groups, focusing on the diagnostic efficacy of grip strength, DE, DTF, and their combined application in diagnosing ICU-AW. A total of 95 patients were initially considered for inclusion in this study. Following the exclusion of 20 patients, a final cohort of 75 patients were enrolled, comprising of 32 patients (42.6%) diagnosed with ICU-AW and 43 patients (57.4%) classified as non-ICU-AW. Comparative analysis revealed that grip strength, DE, and DTF were significantly lower in the ICU-AW group (P < 0.05). Subgroup analysis specific to male patients demonstrated a noteworthy decrease in grip strength, DE, and DTF within the ICU-AW group (P < 0.05). Receiver operating characteristic curve analysis indicated statistically significant diagnostic value for ICU-AW with grip strength, DE, DTF, and grip strength and diaphragmatic ultrasound (P < 0.01). Furthermore, it was observed that the amalgamation of grip strength and diaphragmatic ultrasound significantly enhanced the diagnostic accuracy of ICU-AW in patients who are critically ill. Grip strength, DE, DTF, and the combined use of grip strength with diaphragm ultrasound demonstrated diagnostic efficacy in ICU-AW. Notably, the integration of grip strength with diaphragm ultrasound exhibited a heightened capacity to enhance the diagnostic value specifically in patients diagnosed who are critically ill with ICU-AW.

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. 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. 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). 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.

Objective: To assess the predictive value of diaphragmatic ultrasound for successful weaning from mechanical ventilation. Methodology: This cross-sectional validation study was conducted in the ICU at PIMS from November 2023 to April 2024, on mechanically ventilated patients aged 16–60 years with a pre-illness frailty score of &lt;3 who met weaning criteria. After a successful 1-hour spontaneous breathing trial (SBT), the Rapid Shallow Breathing Index (RSBI) was recorded, and diaphragm ultrasound was performed by an independent anesthetist to measure diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF). Ultrasound assessments were done using curvilinear and linear probes in a semi-recumbent position. Maintaining the spontaneous breathing for 48 hours post-extubation was defined as successful weaning, while failure was defined as needing re-intubation within 48 hours. Data were analyzed using SPSS version 26. Results: Overall average age of patients was 37.82 years. There were 19 (28.8%) females and 47(71.2%) males. Mean days on mechanical ventilator was 5.48 days. The outcomes of weaning showed that 59 participants (89.4%) were successfully weaned, while 7 participants (10.6%) experienced failure in the weaning process. Further analysis of outcomes of weaning showed insignificant association with the gender and (P&gt;0.05). Conclusion: Diaphragmatic ultrasound provided a comprehensive assessment of diaphragmatic function and its role in predicting weaning outcomes. The high success rate suggests that diaphragmatic ultrasound could be a valuable tool in clinical practice for identifying patients who are likely to be successfully weaned from mechanical ventilation, thereby improving patient management and outcomes.

Weaning failure is common in mechanically ventilated patients, and whether ultrasound (US) can predict weaning outcome remains controversial. This review aims to evaluate the diaphragmatic function measured by US as a predictor of weaning outcome. PubMed was searched to identify original articles about the use of diaphragmatic US in ICU patients. A total of 61 citations were retrieved initially; available data of 26 studies were included in this review. To assess diaphragmatic dysfunction in adults, six studies evaluated excursion, five evaluated thickening fraction, and both in nine. Despite heterogeneity in the diagnostic accuracy of diaphragm US among the studies, the sonographic indices showed good diagnostic performance for predicting weaning outcome. Diaphragmatic US can be a useful and accurate tool to detect diaphragmatic dysfunction in critically ill patients and predict weaning outcome.

An 8-year-old boy, with a medical history of congenital myotonic dystrophy (CMD) and scoliosis, was admitted to the paediatric intensive care unit (PICU) with a lower respiratory tract infection. He...