A narrative review of diaphragm ultrasound to predict weaning from mechanical ventilation: where are we and where are we heading?

Advances in Point-of-Care Ultrasound in Pediatric Acute Care Medicine

Pediatric point-of-care ultrasonography (POCUS) has grown in utilization and is now an integral part of pediatric acute care. Applications within the pediatric critical care, neonatology and pediatric emergency were once limited to evaluation of undifferentiated shock states, abdominal free fluid assessments in trauma resuscitation and procedural guidance. The body of pediatric POCUS literature is ever expanding and recently published international consensus guidelines are available to guide implementation into clinical practice. The authors present a review of emerging applications and controversies within thoracic, hemodynamic, neurologic, and ocular POCUS in pediatric acute care medicine.

The effects of robot-assisted laparoscopic surgery with Trendelenburg position on short-term postoperative respiratory diaphragmatic function

OBJECTIVE

To study how Pneumoperitoneum under Trendelenburg position for robot-assisted laparoscopic surgery impact the perioperative respiratory parameters, diagrammatic function, etc. METHODS: Patients undergoing robot-assisted laparoscopic surgery in the Trendelenburg position and patients undergoing general surgery in the supine position were selected. The subjects were divided into two groups according to the type of surgery: robot-assisted surgery group and general surgery group. ① Respiratory parameters such as lung compliance, oxygenation index, and airway pressure were recorded at 5 min after intubation, 1 and 2 h after pneumoperitoneum. ② Diaphragm excursion (DE) and diaphragm thickening fraction (DTF) were recorded before entering the operating room (T1), immediately after extubation (T2), 10 min after extubation (T3), and upon leaving the postanesthesia care unit (T4). ③ Peripheral venous blood (5 ml) was collected before surgery and 30 min after extubation and was analyzed by enzyme-linked immunosorbent assay to determine the serum concentration of Clara cell secretory protein 16 (CC16) and surfactant protein D (SP-D).

RESULT

① Compared with the general surgery group (N = 42), the robot-assisted surgery group (N = 46) presented a significantly higher airway pressure and lower lung compliance during the surgery(P < 0.001). ② In the robot-assisted surgery group, the DE significantly decreased after surgery (P < 0.001), which persisted until patients were discharged from the PACU (P < 0.001), whereas the DTF only showed a transient decrease postoperatively (P < 0.001) and returned to its preoperative levels at discharge (P = 0.115). In the general surgery group, the DE showed a transient decrease after surgery(P = 0.011) which recovered to the preoperative levels at discharge (P = 1). No significant difference in the DTF was observed among T1, T2, T3, and T4. ③ Both the general and robot-assisted surgery reduced the postoperative serum levels of SP-D (P < 0.05), while the robot-assisted surgery increased the postoperative levels of CC16 (P < 0.001).

CONCLUSION

Robot-assisted laparoscopic surgery significantly impairs postoperative diaphragm function, which does not recover to preoperative levels at PACU discharge. Elevated levels of serum CC16 after surgery suggest potential lung injury. The adverse effects may be attributed to the prolonged Trendelenburg position and pneumoperitoneum during laparoscopic surgery.

The Role of Ultrasonography in the Process of Weaning from Mechanical Ventilation in Critically Ill Patients

Weaning patients from mechanical ventilation (MV) is a complex process that may result in either success or failure. The use of ultrasound at the bedside to assess organs may help to identify the underlying mechanisms that could lead to weaning failure and enable proactive measures to minimize extubation failure. Moreover, ultrasound could be used to accurately identify pulmonary diseases, which may be responsive to respiratory physiotherapy, as well as monitor the effectiveness of physiotherapists' interventions. This article provides a comprehensive review of the role of ultrasonography during the weaning process in critically ill patients.

The combined use of parasternal intercostal muscle thickening fraction and P0.1 for prediction of weaning outcomes

BACKGROUND

A variety of parameters and diaphragmatic ultrasound in ventilator weaning has been studied extensively, and the findings yield inconsistent conclusions. The parasternal intercostal muscle holds important substantial respiratory reserve capacity when the central drive is enhanced, the predictive value of combining parasternal intercostal muscle ultrasound parameters with P0.1(airway occlusion pressure at 100 msec) in assessing ventilator weaning outcomes is still unknown.

OBJECTIVES

Our study aimed to evaluate the predictive efficacy of parasternal intercostal muscle ultrasound in conjunction with P0.1 in determining weaning failure.

METHODS

We recruited patients who had been admitted to ICU and had been receiving mechanical ventilation for over two days. All patients underwent a half-hour spontaneous breathing trial (SBT) with low-level pressure support ventilation (PSV). They were positioned semi-upright for parasternal intercostal muscle ultrasound evaluations, including parasternal intercostal muscle thickness (PIMT), and parasternal intercostal muscle thickening fraction (PIMTF); P0.1 was obtained from the ventilator. Weaning failure was defined as the need for non-invasive positive pressure ventilation or re-intubation within 48 h post-weaning.

RESULTS

Of the 56 enrolled patients with a mean age of 63.04 ± 15.80 years, 13 (23.2%) experienced weaning failure. There were differences in P0.1 (P = .001) and PIMTF (P = .017) between the two groups, but also in patients with a diaphragm thickness ≥ 2 mm. The predictive threshold values were PIMTF ≥ 13.15% and P0.1 ≥ 3.9 cmH2O for weaning failure. The AUROC for predicting weaning failure was 0.721 for PIMTF, 0.792 for P0.1, and 0.869 for the combination of PIMTF and P0.1.

CONCLUSIONS

The parasternal intercostal muscle thickening fraction and P0.1 are independently linked to weaning failure, especially in patients with normal diaphragm thickness. The combination of parasternal intercostal muscle thickening fraction and P0.1 can serve as a valuable tool for the precise clinical prediction of weaning outcomes.

TRIAL REGISTRATION

Chinese Clinical Trial Registry website (ChiCTR2200065422).

Is the mNutric Score, the Only Independent Risk Factor for Abdominal Muscle Thickness Influencing Weaning?

How to cite this article: Goswami A, Bhattacharya D, Mandal M, Esquinas AM. Is the mNutric Score, the Only Independent Risk Factor for Abdominal Muscle Thickness Influencing Weaning? Indian J Crit Care Med 2023;27(9):686-687.

Ultrasound utilization in the diagnosis of diaphragm dysfunction compared to other modalities: A retrospective study

Objectives

Diaphragm is dome-shaped fibro-muscular assembly, composed of central tendon surrounded by peripheral muscle fibers. It plays a significant role in respiration and maintenance of lumber spine stability. Any condition that interferes with diaphragmatic innervation, contractile muscle function or mechanical coupling to chest wall can cause diaphragm dysfunction; which is usually manifests as elevation at chest radiography. Functional imaging with M-mode ultrasonography has been used in assessment of diaphragm kinetics in a variety of normal and pathological conditions. In this study, we evaluate the departmental ultrasound accuracy in diaphragm motion assessment and compare its results with other institutional parameters.

Methods

We retrospectively reviewed the recorded laboratory investigation and chest radiograph of 163 pediatric patients. A total of 131 patients met clinical inclusion criteria for our study, patients under age of 14 years having clinical suspicion of diaphragmatic dysfunction. Patients having neuromuscular blockers, surgical plication, and phrenic nerve pacing were excluded. The mean age was 1.6 (SD 2.6) years and there were 44.3% of male and 55.7% of female patients.

Results

The data demonstrated that ultrasonography is a highly sensitive and specific diagnostic tool compared to X-ray and laboratory investigation and clinical suspicion. The second-best results were obtained by X-ray and less accurate results were obtained by laboratory investigation.

Conclusion

In proper sonographic technique; diaphragmatic ultrasound appears to be a valid and reliable diagnostic too; for diaphragmatic dysfunction. Diaphragm ultrasound may act as an imaging tool guiding rehabilitation success in diaphragmatic dysfunction cases.

Lung and diaphragm ultrasound in noninvasive respiratory support: A real tool or fashion?

Introduction

Over the past few years, there has been an increase in lung and diaphragm ultrasound applications as a tool to evaluate the outcomes and settings of noninvasive respiratory supports. However, actual clinical practices in this field are yet to be known. The aim of this study was to investigate the current clinical utilization of ultrasound for noninvasive respiratory supports on an international level.

Materials and Methods

The study employed an online survey consisting of 32 items, which was sent via email to intensivists, pulmonologists, emergency medicine physicians, and other specialists with expertise in using ultrasound and/or noninvasive respiratory supports.

Result

We collected 52 questionnaires. The ultrasound study of diaphragm dysfunction was well-known by the majority of respondents (57.7%). Diaphragm performance was used as a weaning failure predictor (48.5%), as a predictor of noninvasive ventilation failure (38.5%) and as a tool for the ventilator settings adjustment (30.8%). In patients with acute respiratory failure, 48.1% used ultrasound to assess the damaged lung area to set up ventilatory parameters, 34.6% to monitor it after noninvasive ventilation application, and 32.7% to match it with the ventilatory settings for adjustment purposes. When administering high flow nasal cannula - oxygen therapy, 42.3% of participants used ultrasound to evaluate lung involvement and assess flow parameters.

Conclusions

Lung and diaphragm ultrasound is an established clinical practice to evaluate noninvasive respiratory supports outcomes and settings. Further studies are needed to evaluate the educational aspects to increase confidence and indications for its use.

The Role of Thoracic Ultrasound for Diagnosis of Diseases of the Chest Wall, the Mediastinum, and the Diaphragm-Narrative Review and Pictorial Essay

The diagnostic capabilities of ultrasound extend far beyond the evaluation of the pleural space and lungs. Sonographic evaluation of the chest wall is a classic extension of the clinical examination of visible, palpable, or dolent findings. Unclear mass lesions of the chest wall can be differentiated accurately and with low risk by additional techniques such as color Doppler imaging, contrast-enhanced ultrasound, and, in particular, ultrasound-guided biopsy. For imaging of mediastinal pathologies, ultrasound has only a complementary function but is valuable for guidance of percutaneous biopsies of malignant masses. In emergency medicine, ultrasound can verify and support correct positioning of endotracheal tubes. Diaphragmatic ultrasound benefits from the real-time nature of sonographic imaging and is becoming increasingly important for the assessment of diaphragmatic function in long-term ventilated patients. The clinical role of thoracic ultrasound is reviewed in a combination of narrative review and pictorial essay.

Ultrasonographic Assessment of Diaphragmatic Function and Its Clinical Application in the Management of Patients with Acute Respiratory Failure

Acute respiratory failure (ARF) is a common life-threatening medical condition, with multiple underlying etiologies. In these cases, many factors related to systemic inflammation, prolonged use of steroids, and lung mechanical abnormalities (such as hyperinflation or increased elastic recoil due to pulmonary oedema or fibrosis) may act as synergic mechanisms leading to diaphragm dysfunction. The assessment of diaphragm function with ultrasound has been increasingly investigated in the emergency department and during hospital stay as a valuable tool for providing additional anatomical and functional information in many acute respiratory diseases. The diaphragmatic ultrasound is a noninvasive and repeatable bedside tool, has no contraindications, and allows the physician to rapidly assess the presence of diaphragmatic dysfunction; this evaluation may help in estimating the need for mechanical ventilation (and the risk of weaning failure), as well as the risk of longer hospital stay and higher mortality rate. This study presents an overview of the recent evidence regarding the evaluation of diaphragmatic function with bedside ultrasound and its clinical applications, including a discussion of real-life clinical cases.

Sonographic assessment of diaphragmatic thickening and excursion as predictors of weaning success in the intensive care unit: A prospective observational study

Background and Aims

Ultrasonographic assessment of diaphragmatic function can be a useful bedside tool in the weaning and extubation of mechanically ventilated patients, especially in patients with difficult weaning, in whom diaphragmatic weakness is suspected. Thus, this study was planned to assess the role of bedside sonographic assessment of diaphragmatic indices such as diaphragmatic thickening fraction (DTf) and diaphragmatic excursion (DE) in predicting successful extubation or extubation failure in weaning eligible patients by comparing the measurements with outcome.

Methods

This prospective observational study was conducted on 50 mechanically ventilated, weaning-ready patients during the spontaneous breathing trial (SBT). The DE and DTf of patients were noted along with conventional parameters of weaning. Probability value <0.05 was considered statistically significant. Receiver operating characteristic (ROC) curves were used for analysis. Area under the curve (AUC) was measured, and sensitivity and specificity for different cut-off values were estimated.

Results

Out of 50 patients, 15 (30%) had SBT failure and 4 had extubation failure. The group with SBT failure had significantly higher rapid shallow breathing index (RSBI) and airway occlusion pressure (P0.1s), whereas DE and DTf were lower compared to the SBT successful group. Strong correlation existed between RSBI, DTf, DE and P0.1s. DTf of nearly 24% (sensitivity 93.5%, specificity 94.7%) and DE of 1.10 cm (84% sensitivity, 89.5% specificity) were associated with best outcome.

Conclusion

Along with conventional parameters of weaning, sonographic assessment of diaphragmatic parameters can be useful in predicting the success of SBT and in avoiding unnecessary extubation failures and thereby help in achieving a successful weaning outcome.

Competencies for Point-of-care Ultrasonography in ICU: An ISCCM Expert Panel Practice Recommendation

How to cite this article: Srinivasan S, Kumar PG, Govil D, Gupta S, Kumar V, Pichamuthu K, et al. Competencies for Point-of-care Ultrasonography in ICU: An ISCCM Expert Panel Practice Recommendation. Indian J Crit Care Med 2022;26(S2):S7-S12.

The effects of external diaphragmatic pacing on diaphragm function and weaning outcomes of critically ill patients with mechanical ventilation: a prospective randomized study

BACKGROUND

Diaphragmatic pacing can improve diaphragm function, which is beneficial for the prognosis of patients treated with prolonged mechanical ventilation (MV). While most previous studies have focused on the role of implanted diaphragm pacing (IDP), our study is the first to examine the effects of external diaphragmatic pacing (EDP) in mechanically ventilated patients. Specifically, the effect of EDP on diaphragm function, the success rate of weaning, the duration of MV (DMV), and the intensive care unit (ICU) length of stay (ILOS) were assessed.

METHODS

From September 2019 to December 2020, a total of 51 mechanically ventilated patients in the ICU of the Sun Yat-sen Memorial Hospital, Sun Yat-sen University were enrolled and randomly divided into an EDP group of 27 patients and a control group of 24 patients. The control group received routine treatment, and the EDP group received EDP treatment in addition to routine treatment. The diaphragm excursion (DE), diaphragm thickening fraction (DTF), DMV, ILOS, and average survival time were recorded to evaluate efficacy.

RESULTS

Patients treated with EDP had increased DE [exp(B) =1.86, 95% CI: 1.39 to 2.50, P<0.001] and DTF [exp(B) =1.35, 95% CI: 1.05 to 1.76, P=0.022], shortened weaning time (P=0.026) and prolonged average survival time (P<0.001) compared to patients who did not receive EDP therapy. Especially in cases with difficult weaning, the improvement of DE and DTF in the EDP treatment group was more obvious than that in the control group (P=0.013 and P=0.032). Moreover, the DTF upon attempted spontaneous breathing trial (SBT) was negatively correlated with the fraction of inspired oxygen (FiO2) [r=-0.54; 95% confidence interval (CI): -0.77 to -0.19; P=0.004], the arterial partial pressure of oxygen (PaO2) (r=-0.58; 95% CI: -0.79 to -0.25; P=0.001), the PaO2/FiO2 ratio (r=-0.52; 95% CI: -0.75 to -0.16; P=0.006), and the serum lactate concentration (Lac) (r=-0.39; 95% CI: -0.68 to 0.003; P=0.046).

CONCLUSIONS

EDP treatment can effectively reduce the DMV and prolong the average survival time of mechanically ventilated patients.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR1900024096.

Diaphragmatic ultrasound in weaning ventilated patients: a reliable predictor?

Timely weaning of mechanical ventilation is clinically difficult, as both early and late discontinuations are associated with adverse events impeding the patient's favorable course in the critical care unit. Many parameters aid in judging whether the patient is going to be safely extubated; however, some remain deficient. We herein describe diaphragmatic ultrasound as a new modality for this purpose, detailing diaphragm excursion and thickness as means of it.

Diyafram ultrasonografisinin weaning başarısını tahmin etmedeki gücü

Amaç: Bu çalışmada amaç; diyafram kalınlığının weaning üzerine etkilerini ultrasonografi (USG) ile değerlendirmektir. Gereç ve Yöntem: Prospektif olarak yapılan bu çalışmada; hastaların demografik özellikleri, yoğun bakıma yatış ve mekanik ventilasyon endikasyonları, ek hastalıkları, diyafram kalınlığı, Sıralı Organ Yetmezliği Değerlendirmesi (SOFA) skoru ve Basitleştirilmiş Akut Fizyoloji Skoru (SAPS) II, mortalite oranı, periferik oksijen satürasyonu (SpO2), IMV süresi, dakika hacmi, solunum sayısı (RR), ekspiratuar hacimleri, RSBI değerleri kaydedildi.Hastalar invaziv mekanik ventilatör (IMV) basınç desteği (PS) modunda 30 dakika boyunca spontan olarak ventile edildi . Diyafram kalınlığı (DT), B moduna ayarlanmış 7-10 MHz lineer ultrason probu kullanılarak ölçüldü. Sağ hemidiyafram, 8. ve 10. interkostal boşluklar arasındaki midaksiller çizgide diyafram ve göğüs kafesinin birleştiği bölgede görüntülendi. Ölçümler sonrasında hastalar stabil hale geldikten sonra 1 saat boyunca T-tüpe alındı. T-tüpte spontan solunum denemeleri (SBT)'ni başarıyla tamamlayan hastalar ekstübe edildi. Hastalar başarılı ve başarısız weaning olmak üzere 2 gruba ayrıldı. Bulgular: Toplam 72 hasta çalışmaya dahil edilme kriterlerini sağlayarak değerlendirilmeye alındı. Hastaların 4 tanesi 24 saatten daha kısa süre IMV desteği aldığı için çalışma dışı bırakıldı. Diyafram kalınlık indeksi (DTI) ve diyafram kalınlaşma fraksiyonu (DTF) oranlarında gruplar arasında bir farklılık gözlenmedi. İnspirasyon sonunu diyafram kalınlığı (DTV) ve ekspirasyon sonunu diyafram kalınlığı (DFRV) olarak tanımlanan diyaframın kalınlık ölçümleri başarılı weaning grubunda daha yüksekti. Weaning başarısını tahmin etmek için DTV'nin en iyi eşik değeri 0.72, DFRV değeri 0.669 olarak bulundu. Sonuç: Weaning başarısı diyafram fonksiyonları, diyafram kalınlık parametreleri ve akciğer kapasiteleri ile yakından ilişkilidir. USG, diyaframı değerlendirmek için kullanılabilecek pratik, hasta başı uygulanabilen, noninvaziv bir yöntemdir. DTV ve DFRV weaning sürecinde başarıyı tahmin edebilecek parametreler arasındadır. DTF ve DTI weaning başarısını öngörmede yetersiz bulundu.

Diaphragm and Phrenic Nerve Ultrasound in COVID-19 Patients and Beyond: Imaging Technique, Findings, and Clinical Applications

The diaphragm, the principle muscle of inspiration, is an under-recognized contributor to respiratory disease. Dysfunction of the diaphragm can occur secondary to lung disease, prolonged ventilation, phrenic nerve injury, neuromuscular disease, and central nervous system pathology. In light of the global pandemic of coronavirus disease 2019 (COVID-19), there has been growing interest in the utility of ultrasound for evaluation of respiratory symptoms including lung and diaphragm sonography. Diaphragm ultrasound can be utilized to diagnose diaphragm dysfunction, assess severity of dysfunction, and monitor disease progression. This article reviews diaphragm and phrenic nerve ultrasound and describes clinical applications in the context of COVID-19.

Integrated ultrasound protocol in predicting weaning success and extubation failure: a prospective observational study

BACKGROUND

Difficulty in weaning from mechanical ventilation is encountered in appro-ximately 20% of patients in the intensive care unit. We assessed the utility of a combined lung, diaphragmatic, and cardiac ultrasound protocol to predict extubation failure.

MATERIAL

All patients extubated following a successful spontaneous breathing trial (SBT) were included in the study. Lung ultrasonography score (LUS), diaphragmatic thickness fraction (DTF), changes in velocity time integral (VTI) to passive leg raise at the beginning of SBT, and change in LUS following SBT were recorded.

RESULTS

A total of 60 patients who underwent successful SBT were included in the study. Twenty-seven patients required either non-invasive or invasive mechanical ventilation during the next 48 hours and were classified as weaning failure (Group F). The remaining 33 patients were designated as weaning success (Group S). Compared to group S, patients in Group F had significantly longer ICU length of stay (6.96 ± 4.30 days vs. 11.66 ± 3.85 days, P < 0.001), higher LUS change during SBT (1 [0-2] vs. 2 [1-4], P < 0.001), lower DTF (30.87 ± 5.32 vs. 27.88 ± 6.24, P = 0.04), and showed lower VTI increment to PLR (13.63 ± 3.44 vs. 9.11 ± 4.59, P < 0.001). Using a binary logistic regression model, DTF < 26% (odds ratio 6.20, 95% CI: 1.06-36.04) and VTI change to PLR < 10.2% (odds ratio 6.16, 95% CI: 1.14-33.13) were found to be significant predictors of weaning failure (P < 0.05). The AUROC for VTI and DTF for predicting weaning failure were 0.79 and 0.64, respectively.

CONCLUSIONS

An integrated ultrasound protocol using a combination of lung, diaphragm, and cardiac sonography was a reliable predictor of weaning failure.

Predictive Value of Diaphragmatic Ultrasonography for the Weaning Outcome in Mechanically Ventilated Children Aged 1-3 Years

BACKGROUND

There are estimated 20% of mechanically ventilated patients having difficulty in weaning from the ventilators, and the weaning process accounts for 40% of the whole ventilation time. Reliable tools are urgently needed to estimate the weaning outcome. Diaphragmatic ultrasonography, as a relatively good predictive method for the adults, was measured in this study, assessing the value of each indicator of diaphragmatic ultrasonography to predict the outcomes of ventilator weaning from mechanically ventilated children of 1-3 years old.

METHODS

Between November 2018 and November 2019, children who were mechanically ventilated and ready for weaning in the pediatric intensive care unit (PICU) were enrolled in the study. Diaphragmatic ultrasonography was performed to the children to measure the right diaphragm excursion (DE), contraction velocity, thickness, and diaphragm thickening fraction (DTF), which were recorded followed by spontaneous breathing trial (SBT). The receiver operator characteristic (ROC) curves were also used to assess the value of each indicator to predict the weaning outcome.

RESULTS

During this study period, a total of 72 children were enrolled, and of them, 56 children passed the weaning process, while 16 children failed. There were significant differences in DE, contraction velocity, thickness, and DTF parameters between the weaning success group and the failure group. The areas under the ROC curves (AUC) and the optimal threshold of the above indicators were as follows: 0.72 and 8.08 mm for DE, 0.71 and 26.1% for right DTF (DTF^R), 0.71 and 20.7% for left DTF (DTF^L), 0.78 and 14.8% for minimum DTF (DTF^MIN), 0.79 and 26.1% for maximum DTF (DTF^MAX), 0.71 and 1.24 mm for maximum diaphragm thickness at the end of inspiration (Dtei^MAX), and 0.65 and 10.0 mm/s for contraction velocity.

CONCLUSION

Diaphragmatic ultrasonography is feasible in guiding ventilator weaning, and the indicators of DE, DTF, and Dtei^MAX guide the weaning more accurately. Among them, DTF may act as a more reliable predictor of weaning by avoiding the influence of diaphragm development in children.

The novel use of diaphragmatic excursion on hospital admission to predict the need for ventilatory support in patients with coronavirus disease 2019

Background

We aimed to evaluate the ability of diaphragmatic excursion at hospital admission to predict outcomes in patients with coronavirus disease-2019 (COVID-19).

Methods

In this prospective observational study, we included adult patients with severe COVID-19 admitted to a tertiary hospital. Ultrasound examination of the diaphragm was performed within 12 h of admission. Other collected data included peripheral oxygen saturation (SpO₂), respiratory rate, and computed tomography (CT) score. The outcomes included the ability of diaphragmatic excursion, respiratory rate, SpO₂, and CT score at admission to predict the need for ventilatory support (need for non-invasive or invasive ventilation) and patient mortality using the area under the receiver operating characteristic curve (AUC) analysis. Univariate and multivariable analyses about the need for ventilatory support and mortality were performed.

Results

Diaphragmatic excursion showed an excellent ability to predict the need for ventilatory support, which was the highest among respiratory rate, SpO₂, and CT score; the AUCs (95% confidence interval [CI]) was 0.96 (0.85–1.00) for the right diaphragmatic excursion and 0.94 (0.82–0.99) for the left diaphragmatic excursion. The right diaphragmatic excursion also had the highest AUC for predicting mortality in relation to respiratory rate, SpO₂, and CT score. Multivariable analysis revealed that low diaphragmatic excursion was an independent predictor of mortality with an odds ratio (95% CI) of 0.55 (0.31–0.98).

Conclusion

Diaphragmatic excursion on hospital admission can accurately predict the need for ventilatory support and mortality in patients with severe COVID-19. Low diaphragmatic excursion was an independent risk factor for in-hospital mortality.

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.

Diaphragm and Lung Ultrasonography During Weaning From Mechanical Ventilation in Critically Ill Patients

Aim: Optimum timing is crucial to avoid negative outcomes of weaning. We aimed to investigate predictive values of diaphragmatic thickening fraction (DTF), diaphragmatic excursion (DE), and anterolateral lung ultrasound (LUS) scores in extubation success and compare with rapid shallow breathing index (RSBI) in patients extubated under traditional parameters.

Methods: Patients undergoing mechanical ventilation for >48 hours were included in the study. In patients planned for extubation, sonographic evaluations of the diaphragm and lung were performed at the T-tube stage. RSBI was achieved in the pressure support (PS) ventilation stage. Predictive values of DTF, DE, and anterolateral LUS scores were compared with RSBI in extubation success.

Results: Sixty-two patients were enrolled in the study. The study population consisted mostly of trauma patients (77%). A cut-off value of 64 was obtained for RSBI. The positive predictive value (PPV) was found at 97% in extubation success. Cut-off values of 27.5 for DTF, 1.3 cm for the DE, and 6.5 for LUS scores were obtained at the T-tube stage, respectively. PPVs of all sonographic parameters were found over 90%. At the first stage, weaning and extubation failures were determined as 35 and 9.6%, respectively. RSBI was found as a powerful parameter in determining extubation success (r=0.774, p≤0.001) and moderately correlated with sonographic parameters.

Conclusion: Investigating the lung and diaphragm via ultrasound provides real-time information to increase extubation success. Cut-off values of 64 for RSBI, 27.5 for DTF, 1.3 cm for the DE, and 6.5 for LUS scores were obtained, respectively, and PPVs of all sonographic parameters were found over 90%. We consider that sonographic evaluations accompanied by an RSBI will increase extubation success in the weaning process.

Extracorporeal support to achieve lung-protective and diaphragm-protective ventilation

PURPOSE OF REVIEW

Extracorporeal support allows ultraprotective controlled and assisted ventilation, which can prevent lung and diaphragm injury. We focused on most recent findings in the application of extracorporeal support to achieve lung protection and diaphragm- protection, as well as on relevant monitoring.

RECENT FINDINGS

A recent randomized trial comparing the efficacy of extracorporeal support as a rescue therapy to conventional protective mechanical ventilation was stopped for futility but post hoc analyses suggested that extracorporeal support is beneficial for patients with very severe acute respiratory distress syndrome. However, the optimal ventilation settings during extracorporeal support are still debated. It is conceivable that they should enable the highest amount of CO2 removal with lowest mechanical power.Extracorporeal CO2 removal can minimize acidosis and enable the use of ultra-protective lung ventilation strategies when hypoxemia is not a major issue. Moreover, it can protect lung and diaphragm function during assisted ventilation through control of the respiratory effort.Lung mechanics, gas exchange, diaphragm electrical activity, ultrasound, electrical impedance tomography could be integrated into clinical management to define lung and diaphragm protection and guide personalized ventilation settings.

SUMMARY

Technological improvement and the latest evidence indicate that extracorporeal support may be an effective tool for lung and diaphragm protection.

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.

Use of intraoperative ultrasonography for identification and management of pneumothorax caused by iatrogenic diaphragm defect: a case report and literature review

Transthoracic ultrasound has been widely accepted for the evaluation of many thoracic diseases, including pleural effusion, atelectasis, pneumothorax, and pneumonia with subpleural effusion. Application of ultrasonography for the diagnosis of pneumothorax is an effective and timely intraoperative technique. We herein present a patient who developed pneumothorax following diaphragmatic injury during laparoscopic cholecystectomy. The pneumothorax was rapidly identified by bedside ultrasound. The compressed lung was successfully re-expanded using positive end-expiratory pressure (PEEP) ventilation under real-time ultrasound monitoring, and closed thoracic drainage was avoided. Therefore, the correct use of ultrasound can identify the adequate PEEP level that is able to promote resolution of pneumothorax induced by diaphragmatic injury.

Diaphragm dysfunction detected with ultrasound to predict noninvasive mechanical ventilation failure: A prospective cohort study

OBJECTIVE

This study aimed to examine the use of point-of-care ultrasonography (POCUS) in detecting diaphragmatic dysfunction (DD) and evaluate its ability to predict noninvasive mechanical ventilation (NIV) failure in patients presented to the emergency department with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

METHODS

In this prospective cohort study, the diaphragm was examined using POCUS in patients with AECOPD. DD was defined as a diaphragm thickening fraction of less than 20% during spontaneous breathing. NIV failure was the primary outcome of the study, and duration of hospital stay and in-hospital mortality were the secondary outcomes. Specificity, sensitivity, positive predictive value, and negative predictive value were estimated for predicting NIV failure in DD and evaluating the diagnostic performance of POCUS.

RESULTS

60 patients were enrolled the study. NIV failure was found in 11 (73.3%) of 15 patients with DD and in 2 (4.4%) of 45 patients without DD. In predicting NIV failure, DD had a sensitivity of 84.6% (95% confidence interval [CI]:54.6-98.1), specificity of 91.5% (95% CI:79.6-97.6), positive predictive value of 73.3% (95% CI:51.2-87.8), and negative predictive value of 95.6% (95% CI:85.7-98.7). The duration of hospital stay was not different between groups (p = .065). No in-hospital mortality was seen in patients without DD.

CONCLUSIONS

DD has high sensitivity and specificity in predicting NIV failure in patients admitted to the emergency department with AECOPD. DD can be assessed by an experienced clinician noninvasively using POCUS in emergency departments.