Ultrasonographic Assessment of Diaphragm Function in Critically Ill Subjects

Association between nutritional risk status and both diaphragmatic dysfunction and diaphragm atrophy in medical ıntensive care unit patients

AIM

critical illness often leads to malnutrition and diaphragmatic dysfunction (DD), common in intensive care units (ICU). Ultrasonography (US) is a potent tool for detecting DD. This study examines the connection between malnutrition risk and DD in ICU patients using ultrasonographic diaphragm measurements in medical ICU patients.

METHODS

we assessed nutritional risk using risk screening tools and mid-upper arm circumference measurements (MUAC). Diaphragm atrophy (DA) and DD were evaluated by measuring diaphragmatic excursion (DE), thickness, and thickening fraction (TF) by US. We then compared these diaphragmatic measurements in patients based on their nutritional risk scores.

RESULTS

of the fifty patients studied, 54 % to 78 % were at risk of malnutrition, 28 % exhibited diaphragm atrophy (DA), and 24 % showed DD upon ICU admission. Malnutrition risk diagnosed by all nutritional risk screening tools was significantly more frequent in patients with DD, while diagnosed by MUAC was considerably higher in patients with DA. A total of 16 patients (32 %) died during their ICU stay, with DD, DA, and malnutrition risks (as identified by the mNUTRIC Score) being more prevalent among non-survivors (p < 0.05). Malnutrition risk (as determined by the mNUTRIC Score) was an independent risk factor for DD [OR (95 % CI): 6.6 (1.3-34), p = 0.03].

CONCLUSION

malnutrition risk may be significantly associated with DD and DA in medical ICU patients upon ICU admission.

Ultrasonography to Access Diaphragm Dysfunction and Predict the Success of Mechanical Ventilation Weaning in Critical Care: A Narrative Review

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Diaphragmatic US can be a useful and accurate tool to detect diaphragmatic dysfunction in critically ill patients and predict weaning outcome.

Perioperative Diaphragm Dysfunction

Diaphragm Dysfunction (DD) is a respiratory disorder with multiple causes. Although both unilateral and bilateral DD could ultimately lead to respiratory failure, the former is more common. Increasing research has recently delved into perioperative diaphragm protection. It has been established that DD promotes atelectasis development by affecting lung and chest wall mechanics. Diaphragm function must be specifically assessed for clinicians to optimally select an anesthetic approach, prepare for adequate monitoring, and implement the perioperative plan. Recent technological advancements, including dynamic MRI, ultrasound, and esophageal manometry, have critically aided disease diagnosis and management. In this context, it is noteworthy that therapeutic approaches for DD vary depending on its etiology and include various interventions, either noninvasive or invasive, aimed at promoting diaphragm recruitment. This review aims to unravel alternative anesthetic and operative strategies that minimize postoperative dysfunction by elucidating the identification of patients at a higher risk of DD and procedures that could cause postoperative DD, facilitating the recognition and avoidance of anesthetic and surgical interventions likely to impair diaphragmatic function.

Ultrasonographic Features of Muscular Weakness and Muscle Wasting in Critically Ill Patients

Muscle wasting begins as soon as in the first week of one's ICU stay and patients with multi-organ failure lose more muscle mass and suffer worse functional impairment as a consequence. Muscle wasting and weakness are mainly characterized by a generalized, bilateral lower limb weakness. However, the impairment of the respiratory and/or oropharyngeal muscles can also be observed with important consequences for one's ability to swallow and cough. Muscle wasting represents the result of the disequilibrium between breakdown and synthesis, with increased protein degradation relative to protein synthesis. It is worth noting that the resulting functional disability can last up to 5 years after discharge, and it has been estimated that up to 50% of patients are not able to return to work during the first year after ICU discharge. In recent years, ultrasound has played an increasing role in the evaluation of muscle. Indeed, ultrasound allows an objective evaluation of the cross-sectional area, the thickness of the muscle, and the echogenicity of the muscle. Furthermore, ultrasound can also estimate the thickening fraction of muscle. The objective of this review is to analyze the current understanding of the pathophysiology of acute skeletal muscle wasting and to describe the ultrasonographic features of normal muscle and muscle weakness.

Imaging of the Diaphragm Following Cardiac Surgery: Focus on Ultrasonographic Assessment

Diaphragm dysfunction is a common complication following cardiac surgery. Its clinical impact is variable, ranging from the absence of symptoms to the acute respiratory failure. Post-operative diaphragm dysfunction may negatively affect patients' prognosis delaying the weaning from the mechanical ventilation (MV), extending the time of hospitalization and increasing mortality. Ultrasonography is a valid tool to evaluate diaphragmatic impairment in different settings, like the Intensive Care Unit, to predict successful weaning from the MV, and the Cardiovascular Rehabilitation Unit, to stratify patients in terms of risk of functional recovery failure. The aim of this review is to describe the pathophysiology of post-cardiac surgery diaphragm dysfunction, the techniques used for its diagnosis and the potential applications of diaphragm ultrasound.

Prediction of Weaning Outcome from Mechanical Ventilation Using Ultrasound Assessment of Parasternal Intercostal Muscle Thickness

Background

Monitoring the function of parasternal intercostal muscles provides information on respiratory load and capacity and thus can be a weaning monitoring tool.

Objective

The goal was to study the diagnostic accuracy of parasternal intercostal muscle thickness fraction (PICTF%) as a predictor of weaning.

Materials and methods

A prospective observational study on consecutively admitted patients who were intubated and mechanically ventilated for a duration of at least 48 hours was carried out. When an SBT was planned by the treating physician, the study examiner performed the ultrasound measurements of parasternal intercostal muscle thickness (inspiration and expiration) and thickening fraction using M-mode ultrasonography (USG). The PICTF% was calculated as "(peak inspiratory thickness - end-expiratory thickness)/end-expiratory thickness) × 100." Weaning failure was defined if the patient had a failed spontaneous breathing trial (SBT) or the need for a reintubation within 48 hours following extubation. The SBT failure was defined as the need to connect the patient back to the ventilator prior to its completion due to any reason as decided by the clinician.

Results

Of 81 screened patients, 60 patients met the inclusion criteria, of whom 49 patients had successful SBT, and 48 patients could be successfully extubated. The PMTF% cut-off value more than or equal to 15.38% was associated with the best sensitivity (75%) and specificity (87.8%) in predicting extubation failure.

Conclusion

The PICTF% has a good diagnostic accuracy in predicting weaning failure.

How to cite this article

Ramaswamy A, Kumar R, Arul M, Ish P, Madan M, Gupta NK, et al. Prediction of Weaning Outcome from Mechanical Ventilation Using Ultrasound Assessment of Parasternal Intercostal Muscle Thickness. Indian J Crit Care Med 2023;27(10):704-708.

Value of Diaphragm Ultrasonography for Extubation: A Single-Blinded Randomized Clinical Trial

Introduction

Daily evaluation of mechanically ventilated (MV) patients is essential for successful extubation. Proper withdrawal prevents complications and reduces the cost of hospitalization in the intensive care unit (ICU). Diaphragm ultrasonography (DUS) has emerged as a potential instrument for determining whether a patient is ready to be extubated. This study compared the efficacy rate of extubation using a standard withdrawal protocol and DUS in patients with MV.

Methods

A randomized, parallel, single-blind, controlled study was conducted on ICU patients undergoing MV. Patients were randomly assigned to either the control (conventional weaning protocol) group or intervention (DUS-guided weaning) group in a 1 : 1 ratio. The primary outcome measure was the rate of reintubation and hospital mortality.

Results

Forty patients were randomized to the trial. The mean age of the sample was 70 years, representing an older population. The extubation success rate was 90% in both groups. There was no reintubation in the first 48 hours and only two reintubations in both groups between the second and seventh days. The hospital mortality risk in patients with acute kidney injury was positively correlated with age and the need for hemodialysis. Discussion. This study demonstrates the usefulness of DUS measurement protocols for withdrawing MV. The rate of reintubation was low for both cessation methods. As a parameter, the diaphragm thickness fraction comprehensively evaluates the diaphragm function. The results demonstrate that DUS has the potential to serve as a noninvasive tool for guiding extubation decisions. In conclusion, using DUS in patients with respiratory failure revealed no difference in reintubation rates or mortality compared with the conventional method. Future research should concentrate on larger, multicentered, randomized trials employing a multimodal strategy that combines diaphragmatic parameters with traditional clinical withdrawal indices.

Diaphragm Dysfunction and ICU-Acquired Weakness in Septic Shock Patients with or without Mechanical Ventilation: A Pilot Prospective Observational Study

Sepsis is a risk factor for diaphragm dysfunction and ICU-acquired weakness (ICU-AW); however, the impact of mechanical ventilation (MV) on these relationships has not been thoroughly investigated. This study aimed to compare the incidence of diaphragm dysfunction and ICU-AW in patients with septic shock, with and without MV. We conducted a single-center prospective observational study that included consecutive patients diagnosed with septic shock admitted to the ICU between March 2021 and February 2022. Ultrasound measurements of diaphragm thickness and manual measurements of limb muscle strength were repeated after ICU admission. The incidences of diaphragm dysfunction and ICU-AW, as well as their associations with clinical outcomes, were compared between patients with MV and without MV (non-MV). Twenty-four patients (11 in the MV group and 13 in the non-MV group) were analyzed. At the final measurements in the MV group, eight patients (72.7%) had diaphragm dysfunction, and six patients (54.5%) had ICU-AW. In the non-MV group, 10 patients (76.9%) had diaphragm dysfunction, and three (23.1%) had ICU-AW. No association was found between diaphragm dysfunction and clinical outcomes. Patients with ICU-AW in the MV group had longer ICU and hospital stays. Among patients with septic shock, the incidence of diaphragm dysfunction was higher than that of ICU-AW, irrespective of the use of MV. Further studies are warranted to examine the association between diaphragm dysfunction and clinical outcomes.

The increase in diaphragm thickness in preterm infants is related to birth weight: a pilot study

Diaphragm ultrasound (DU) has been used in adult and pediatric critical patients in relation to prediction of extubation success or to detect diaphragm dysfunction, but there is a lack of evidence in neonates. Our aim is to study the evolution of diaphragm thickness in preterm infants, as well as related variables. This prospective monocentric observational study included preterm infants born before 32 weeks (PT32). We performed DU to measure right and left inspiratory and expiratory thickness (RIT, LIT, RET, and LET) and calculated the diaphragm-thickening fraction (DTF) in the first 24 h of life and then weekly until 36 weeks postmenstrual age, death, or discharge. Using multilevel mixed-effect regression, we evaluated the influence of time since birth on diaphragm measurements, as well as bronchopulmonary dysplasia (BPD), birth weight (BW), and days of invasive mechanical ventilation (IMV). We included 107 infants, and we performed 519 DUs. All diaphragm thickness increased with time since birth, but the only additional variable that influenced this growth was BW: beta coefficients RIT = 0.00006; RET = 0.00005; LIT = 0.00005; and LET = 0.00004, p < 0.001. Right DTF values remained stable since birth but left DTF increased with time only in infants with BPD.   Conclusion: In our population we found that the higher the BW, the higher diaphragm thicknesses at birth and follow-up. Contrary to the previously published findings in adult and pediatric settings, we were unable to describe a relationship between days of IMV and diaphragm thickness in PT32. The final diagnosis of BPD does not influence this increase either, but it does increase left DTF. What is Known: • Diaphragm thickness and diaphragm thickening fraction have been related to the time on invasive mechanical ventilation in adults and pediatric patients, as well as with extubation failure. • Very few evidence is yet available on the use of diaphragmatic ultrasound in preterm infants. What is New: • Birth weight is the only variable related to diaphragm thickness in preterm infants born before 32 weeks postmenstrual age. • Days of invasive mechanical ventilation do not influence diaphragm increase in thickness in preterm infants.

Assessment of Inspiratory Effort in Spontaneously Breathing COVID-19 ARDS Patients Undergoing Helmet CPAP: A Comparison between Esophageal, Transdiaphragmatic and Central Venous Pressure Swing

INTRODUCTION

The clinical features of COVID-19 are highly variable. It has been speculated that the progression across COVID-19 may be triggered by excessive inspiratory drive activation. The aim of the present study was to assess whether the tidal swing in central venous pressure (ΔCVP) is a reliable estimate of inspiratory effort.

METHODS

Thirty critically ill patients with COVID-19 ARDS underwent a PEEP trial (0-5-10 cmH₂O) during helmet CPAP. Esophageal (ΔPes) and transdiaphragmatic (ΔPdi) pressure swings were measured as indices of inspiratory effort. ΔCVP was assessed via a standard venous catheter. A low and a high inspiratory effort were defined as ΔPes ≤ 10 and  >15 cmH2O, respectively.

RESULTS

During the PEEP trial, no significant changes in ΔPes (11 [6-16] vs. 11 [7-15] vs. 12 [8-16] cmH2O, p = 0.652) and in ΔCVP (12 [7-17] vs. 11.5 [7-16] vs. 11.5 [8-15] cmH2O, p = 0.918) were detected. ΔCVP was significantly associated with ΔPes (marginal R² 0.87, p < 0.001). ΔCVP recognized both low (AUC-ROC curve 0.89 [0.84-0.96]) and high inspiratory efforts (AUC-ROC curve 0.98 [0.96-1]).

CONCLUSIONS

ΔCVP is an easily available a reliable surrogate of ΔPes and can detect a low or a high inspiratory effort. This study provides a useful bedside tool to monitor the inspiratory effort of spontaneously breathing COVID-19 patients.

Evaluation of IntelliVent-ASV® and PS-SIMV Mode Using Ultrasound (US) Measurements in Terms of Diaphragm Atrophy

BACKGROUND

 Mechanical ventilation is a life-saving intervention for critically ill patients, but it can also lead to diaphragm atrophy, which may prolong the duration of mechanical ventilation and the length of stay in the intensive care unit. IntelliVent-ASV® (Hamilton Medical, Rhäzüns, Switzerland) is a new mode of ventilation that has been developed to reduce diaphragm atrophy by promoting spontaneous breathing efforts. In this study, we aimed to evaluate the effectiveness of IntelliVent-ASV® and pressure support-synchronized intermittent mandatory ventilation (PS-SIMV) mode in reducing diaphragm atrophy by measuring diaphragm thickness using ultrasound (US) imaging.

METHODS

 We enrolled 60 patients who required mechanical ventilation due to respiratory failure and were randomized into two groups: IntelliVent-ASV^® and PS-SIMV. We measured the diaphragm thickness using US imaging at admission and on the seventh day of mechanical ventilation.

RESULTS

Our results showed that diaphragm thickness decreased significantly in the PS-SIMV group but remained unchanged in the IntelliVent-ASV^® group. The difference in diaphragm thickness between the two groups was statistically significant on the seventh day of mechanical ventilation.

CONCLUSIONS

IntelliVent-ASV^® may reduce diaphragm atrophy by promoting spontaneous breathing efforts. Our study suggests that this new mode of ventilation may be a promising approach to preventing diaphragm atrophy in mechanically ventilated patients. Further studies using invasive measures of diaphragm function are warranted to confirm these findings.

A new non-invasive index for the prediction of endotracheal intubation in patients with SARS COVID-19 infection, in the emergency department, pilot study

BACKGROUND

In the current context of the SARS COVID-19 pandemic, where the main cause of death is respiratory failure, and since early recognition would allow timely measures to be implemented and probably improve outcomes, it is important to have tools that allow the emergency room to predict quickly and without the use of large resources which will need invasive mechanical ventilation. This study proposes using a new predictive index of noninvasive characteristics, based on the relationship between oxygenation and work of breathing measured by ultrasound-assessed diaphragmatic function, for the need for invasive mechanical ventilation in patients with SARS-COV2 infection who are admitted to the emergency department.

METHODS

A prospective predictive cohort study was performed, collecting all patients admitted to the emergency room with respiratory failure (not severe or in imminent respiratory arrest) and a confirmed diagnosis of SARS-CoV-2 pneumonia. Diaphragmatic excursion measurements were taken within the first 24 h after admission to the department. The relationship between diaphragmatic excursion and SAFI was calculated, establishing the ultrasound diaphragmatic excursion So2/FiO2 index (U.D.E.S.I). The index's performance was determined by analysis of sensitivity, specificity, and area under the curve (AUC).

RESULTS

This pilot study analyzed the first 100 patients enrolled and found in-hospital mortality of 19%, all patients who died required mechanical ventilation, the right index showed a specificity of 82.4% with a sensitivity of 76.9%, likewise for the left index an overall specificity of 90.5% with a sensitivity of 65.3% was found. The ideal cut-off point for the right index is 1.485, and for the left index, the threshold point was 1.856. AUC of the right index is 0.798 (0.676-0.920) and of the left index 0.793 (0.674-0.911), when comparing them no significant differences were found between these values p = 0.871.

CONCLUSION

The relationship of So2/FiO2 and diaphragm excursion measured by both right and left ultrasound could predict the need for mechanical ventilation of the patient with COVID-19 pneumonia in the emergency room and could constitute a valuable tool since it uses noninvasive parameters and is easily applicable at the patient's bedside. However, a more extensive study is needed to validate these preliminary results.

Intraoperative Ventilator Management of the Critically Ill Patient

Strategies for the intraoperative ventilator management of the critically ill patient focus on parameters used for lung protective ventilation with acute respiratory distress syndrome, preventing or limiting the deleterious effects of mechanical ventilation, and optimizing anesthetic and surgical conditions to limit postoperative pulmonary complications for patients at risk. Patient conditions such as obesity, sepsis, the need for laparoscopic surgery, or one-lung ventilation may benefit from intraoperative lung protective ventilation strategies. Anesthesiologists can use risk evaluation and prediction tools, monitor advanced physiologic targets, and incorporate new innovative monitoring techniques to develop an individualized approach for patients.

Update on Lean Body Mass Diagnostic Assessment in Critical Illness

Acute critical illnesses can alter vital functions with profound biological, biochemical, metabolic, and functional modifications. Despite etiology, patient's nutritional status is pivotal to guide metabolic support. The assessment of nutritional status remains complex and not completely elucidated. Loss of lean body mass is a clear marker of malnutrition; however, the question of how to investigate it still remains unanswered. Several tools have been implemented to measure lean body mass, including a computed tomography scan, ultrasound, and bioelectrical impedance analysis, although such methods unfortunately require validation. A lack of uniform bedside measurement tools could impact the nutrition outcome. Metabolic assessment, nutritional status, and nutritional risk have a pivotal role in critical care. Therefore, knowledge about the methods used to assess lean body mass in critical illnesses is increasingly required. The aim of the present review is to update the scientific evidence regarding lean body mass diagnostic assessment in critical illness to provide the diagnostic key points for metabolic and nutritional support.

Diaphragmatic Dynamics and Thickness Parameters Assessed by Ultrasonography Predict Extubation Success in Critically Ill Patients

INTRODUCTION

A frequent cause of weaning and extubation failure in critically ill mechanically ventilated patients is diaphragm muscle dysfunction. Ultrasound (US) evaluation of the diaphragm yields important data regarding its thickness (diaphragm thickening fraction [TFdi]) and its movement or excursion (diaphragmatic dynamics) that reveal the presence of diaphragmatic dysfunction.

METHODS

Cross-sectional study, which included patients older than 18 years with invasive mechanical ventilation with an expected duration of more than 48 h, in a tertiary referral center in Colombia. The excursion of the diaphragm, inspiratory and expiratory thickness, and TFdi were evaluated by US. Prevalence and use of medications were evaluated, and the association with failure in ventilatory weaning and extubation was analyzed.

RESULTS

Sixty-one patients were included. The median age and APACHE IV score were 62.42 years and 78.23, respectively. The prevalence of diaphragmatic dysfunction (assessed by excursion and TFdi) was 40.98%. The sensibility, specificity, positive predictive value, and negative predictive value for TFdi < 20% was 86%, 24%, 75%, and 40%, respectively, with an area under the receiver operating characteristic (ROC) curve of 0.6. The ultrasonographic analysis of excursion of the diaphragm, inspiratory and expiratory thickness, and TFdi (>20%) allow in its set and with normal values, predict success or failure for the extubation with an area under the ROC curve of 0.87.

CONCLUSION

Diaphragmatic dynamics and thickness parameters together assessed by ultrasonography could predict the success of extubation in critically ill patients in Colombia, based on the finding of diaphragmatic dysfunction.

The fully engaged inspiratory muscle training reduces postoperative pulmonary complications rate and increased respiratory muscle function in patients with upper abdominal surgery: a randomized controlled trial

BACKGROUND

Upper abdominal surgical treatment may reduce respiratory muscle function and mucociliary clearance, which might be a cause of postoperative pulmonary complications (PPCs). Threshold inspiratory muscle training (IMT) may serve as an effective modality to improve respiratory muscle strength and endurance in patients. However, whether this training could help patients with upper abdominal surgery remains to be determined. The aim of the present investigation was to determine the effect of a fully engaged IMT on PPCs and respiratory function in patients undergoing upper abdominal surgery. We hypothesized that the fully engaged IMT could reduce PPCs and improve respiratory muscle function in patients with upper abdominal surgery.

METHODS

This is a randomized controlled trial (RCT) with 28 patients who underwent upper abdominal surgery. Patients were randomly assigned to the control (CLT) group or the IMT group. The CTL group received regular health care. The IMT group received 3 weeks of IMT with 50% of MIP as the initial intensity before the operation. The intensity of MIP increased by 5-10% per week. The IMT was continued for 4 weeks after the operation. The study investigated the outcomes including PPCs, respiratory muscle strength, diaphragmatic function, cardiopulmonary function, and quality of life (QoL).

RESULTS

We found that IMT improved respiratory muscle strength and diaphragmatic excursion. IMT also had a beneficial effect on the incidence of postoperative pulmonary complications (PPCs) compared to CLT care.

CONCLUSION

The results from this study revealed that IMT provided positive effects on parameters associated with the respiratory muscle function and reduced the incidence of PPCs. We propose that fully engaged IMT should be a part of clinical management in patients with upper abdominal surgery.KEY MESSAGESThe fully engaged inspiratory muscle training reduces postoperative pulmonary complications rate in patients with upper abdominal surgery.The fully engaged inspiratory muscle training increases maximal inspiratory pressure in patients with upper abdominal surgery.The fully engaged inspiratory muscle training increases diaphragm function in patients with upper abdominal surgery.The fully engaged inspiratory muscle training increases the quality of life in patients with upper abdominal surgery.

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.

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.

Effect of Acupuncture on Diaphragm Function in Healthy Volunteers: A Pilot Clinical Study

Introduction

In western medicine, the diaphragm is the main inspiratory muscle. It is involved in the postural control of the trunk and contributes to balance performance. In traditional Chinese medicine (TCM), the diaphragm represents a gateway between the lower and upper parts of the body, and it regulates the descending and ascending functions of the whole organism. The aim of this study was to assess the effect of acupuncture on diaphragm function.

Methods

A proof-of-concept, prospective, controlled, pilot trial in healthy volunteers. Respiratory rate, inspired volume, diaphragm excursion, and thickening were measured during tidal and maximal breathing at baseline and after sham or real acupuncture. Acupuncture was performed on Yanglingquan (GB34), Tai Chong (LV3), Danzhong (CV17), Geshu (BL17), and Geguan (BL46).

Results

Ten participants were enrolled (6 males, weight 71 ± 12 kg, height 173 ± 9 cm, BMI 21 ± 1.3 kg/m²). During tidal breathing, tidal volume, diaphragm displacement, and end-expiratory diaphragm thickness did not change with sham or real acupuncture as compared to baseline; thickening ratio was 43.5 ± 16.6 vs. 31.3 ± 14.9 (sham) vs. 30.8 ± 15.3% (baseline), p=0.1066. During breaths at vital capacity, the acupuncture group, as compared to both baseline and sham acupuncture, had a trend toward a larger tidal volume (3840 ± 690 vs. 3110 ± 880 vs. 3230 ± 750 ml, p=0.1247) and showed a significantly higher thickening ratio (270.6 ± 136.4 vs. 172.4 ± 57.4 vs. 188.6 ± 41.7%, p=0.0414).

Conclusions

Acupuncture significantly influenced diaphragm function in healthy volunteers, improving its inspiratory thickening fraction during breaths at vital capacity, as compared to no or sham acupuncture.

Diaphragmatic excursion by ultrasound: reference values for the normal population; a cross-sectional study in Egypt

Background

Measurement of diaphragmatic motion by ultrasound is being utilized in different aspects of clinical practice. Defining reference values of the diaphragmatic excursion is important to identify those with diaphragmatic motion abnormalities. This study aimed to define the normal range of diaphragmatic motion (reference values) by Mmode ultrasound for the normal population.

Methods

Healthy volunteers were included in this study. Those with comorbidities, skeletal deformity, acute or chronic respiratory illness were excluded. Diaphragmatic ultrasound in the supine position was performed using a lowfrequency probe. The B-mode was applied for diaphragmatic identification, and the M-mode was employed for the recording of the amplitude of diaphragm contraction during quiet breathing, deep breathing and sniffing.

Results

The study included 757 healthy subjects [478 men (63.14%) and 279 women (36.86%)] with normal spirometry and negative history of previous or current respiratory illness. Their mean age and BMI were 45.17 ±14.84 years and 29.36±19.68 (kg/m²). The mean right hemidiaphragmatic excursion was 2.32±0.54, 5.54±1.26 and 2.90±0.63 for quiet breathing, deep breathing and sniffing, respectively, while the left hemidiaphragmatic excursion was 2.35±0.54, 5.30±1.21 and 2.97±0.56 cm for quiet breathing, deep breathing and sniffing, respectively. There was a statistically significant difference between right and left diaphragmatic excursion among all studied subjects. The ratio of right to left diaphragmatic excursion during quiet breathing was (1.009±0.19); maximum 181% and minimum 28%. Only 19 cases showed a right to left ratio of less than 50% (5 men and 14 women). The diaphragmatic excursion was higher in males than females. There was a significant difference in diaphragmatic excursion among age groups. Age, sex and BMI significantly affected the diaphragmatic motion.

Conclusions

Diaphragmatic excursion values presented in this study can be used as reference values to detect diaphragmatic dysfunction in clinical practice. Diaphragmatic motion is affected by several factors including age, sex and body mass index.

Time course of the Bioelectrical Impedance Vector Analysis and muscular ultrasound in critically ill patients

PURPOSE

Several different tools have been developed to integrate the clinical and biochemical nutritional evaluations in critical care patients. Aims of this study were to evaluate the changes in the Bioelectrical Impedance Vector Analysis (BIVA) and ultrasonographic features of the diaphragm (DTee) and rectus femoris (RFCSA) during the first week of ICU stay.

MATERIALS AND METHODS

Ninety-six adult mechanically ventilated patients enrolled within 24 h after the admission to the ICU (T1). RFCSA and diaphragm end-expiratory thickness were measured, as well as BIVA parameters. Anthropometric data and biochemical parameters were collected. The measurements were repeated on the 3rd (T3) and 7th (T7) days of ICU stay.

RESULTS

During the study period, the phase angle significantly decreased by 21%, reactance by 27%, and resistance by 11%. Both RFCSA and DTee significantly decreased, while neither were correlated to any BIVA parameter. DTee was considerably higher in survivors vs. non-survivors.

CONCLUSIONS

Body composition is significantly modified after one week of ICU stay. BIVA may be useful in the definition of hydration state, while it does not seem to track muscle mass. Different temporal trends of specific BIVA and muscle ultrasound parameters were found in patients with high or low severity of illness.

The Feasibility of Ultrasonographic Diaphragmatic Excursion in Healthy Dogs: Effect of Positioning, Diaphragmatic Location, and Body Weight of Dogs

Diaphragmatic excursion (DE) has been utilized for detecting respiratory related problems in humans. However, several factors should be considered such as the ultrasound technique and factors intrinsic to patients. Nevertheless, knowledge of the effect of these factors on DE in dogs is still lacking. The aim of this study was to evaluate the proper ultrasound technique by varying postures and diaphragmatic locations for DE measurement and to explore intrinsic factors such as diaphragmatic sides, sex, and body weight of dogs on DE. The prospective, analytic, cross-sectional study included 44 healthy dogs; 12 beagles and 32 dogs of other breeds. The experiment was divided into (i) an exploration of the proper ultrasound technique by varying postures (supine, standing, and recumbent in each of the right and left lateral positions), diaphragmatic locations (middle crus and proximal to the last rib), and diaphragmatic sublocations (xiphoid, mid, and proximal rib) for detection of DE and (ii) the evaluation of canine intrinsic factors affecting DE. The results show that the mid-diaphragmatic sublocation in the middle crus area in almost all positions revealed the highest percentage DE detection. However, DEs were revealed to be more accessible in the supine position. There was no significant difference in DE between the right and the left diaphragms or between the sexes of beagle dogs. However, body weight was significantly correlated with the DE among dogs of various sizes. In conclusion, the posture of the dogs and the diaphragmatic location can affect DE evaluation. Neither sex nor diaphragmatic side had an influence, but body weight was revealed as a major factor in DE in dogs.

Peri-operative diaphragm ultrasound as a new method of recognizing post-operative residual curarization

Background

This study sought to evaluate the diagnostic accuracy of peri-operative diaphragm ultrasound in assessing post-operative residual curarization (PORC).

Methods

Patients undergoing non-thoracic and non-abdominal surgery under general anaesthesia were enrolled from July 2019 to October 2019 at Peking Union Medical College Hospital. A train-of-four ratio (TOFr) lower than 0.9 was considered as the gold standard for PORC. Diaphragm ultrasound parameters included diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF) during quiet breathing (QB) and deep breathing (DB). The diaphragm excursion fraction (DEF) was calculated as the DE-QB divided by the DE-DB. The diaphragm excursion difference (DED) was defined as DE-DB minus DE-QB. Receiver operating characteristic curve analysis was used to determine the cut-off values of ultrasound parameters for the prediction of PORC.

Results

In total, 75 patients were included, with a PORC incidence of 54.6%. The DE-DB and DED were positively correlated with the TOFr, while the DEF was negatively correlated with the TOFr. The DE-DB cut-off value for predicting PORC was 3.88 cm, with a sensitivity of 85.4% (95% confidence interval [CI]: 70.1–93.9%), specificity of 64.7% (95% CI: 46.4–79.7%), positive likelihood ratio of 2.42 (95% CI 1.5–3.9), and negative likelihood ratio of 0.23 (95% CI: 0.1–0.5). The DED cut-off value was 1.5 cm, with a specificity of 94.2% (95% CI: 80.3–99.3%), sensitivity of 63.4% (95% CI: 46.9–77.9%), positive likelihood ratio of 10.78 (95% CI: 2.8–42.2), and negative likelihood ratio of 0.39 (95% CI: 0.3–0.6).

Conclusions

Peri-operative diaphragm ultrasound may be an additional method aiding the recognition of PORC, with DED having high specificity.

The role of diaphragmatic ultrasound as a predictor of successful extubation from mechanical ventilation in respiratory intensive care unit

Background

The diaphragm muscle whose dysfunction may be very common in patients undergoing mechanical ventilation (Ferrari G, De Filippi G, Elia F, Panero F, Volpicelli G, Aprà F. Crit Ultrasound J 6:8, 2014). Aim: To evaluate real-time ultrasound in the evaluation of diaphragmatic thickening, thickening fraction, and/or excursion to predict extubation outcomes. We aimed to compare these parameters with other traditional weaning measures is a fundamental.

Results

Out of 80 included patients, 20 (25%) have failed extubation. Diaphragmatic thickening (DT), thickening fraction (DTF), and/or excursion (DE) were significantly higher in the successful group compared to those who failed extubation (p < 0.05). Cutoff values of diaphragmatic measures associated with successful extubation (during tidal breathing) were ≥ 17 mm for DE; ≥ 2.1 cm for DT inspiration; ≥ 15.5 mm for DT expiration, functional residual capacity (FRC); and ≥ 32.82% for DTF %, giving 68%, 95%, 62%, and 90% sensitivity, respectively, and 65%, 100%, 100%, and 75% specificity, respectively. Cutoff values of diaphragmatic parameters associated with successful extubation (during deep breathing) were > 28.5 mm DT Insp, total lung capacity (TLC); >22.5mm DT Exp (RV); >37 DTF %; and > 31 mm DE, giving 100%, 73%, 97%, and 75% sensitivity and 65%, 75%, 100%, and 55% specificity, respectively. Rapid shallow breathing index (RSBI) had 47% sensitivity but 90% specificity.

Conclusion

Ultrasound evaluation of diaphragmatic parameters could be a good predictor of weaning in patients who passed the T-tube.

Qualitative and quantitative muscle ultrasound changes in patients with COVID-19-related ARDS

OBJECTIVES

Severe forms of the novel coronavirus-19 (COVID-19) are associated with systemic inflammation and hypercatabolism. The aims of this study were to compare the time course of the size and quality of both rectus femoris and diaphragm muscles between critically ill, COVID-19 survivors and non-survivors and to explore the correlation between the change in muscles size and quality with the amount of nutritional support delivered and the cumulative fluid balance.

METHODS

This was a prospective observational study in the general intensive care unit (ICU) of a tertiary care hospital for COVID-19. The right rectus femoris cross-sectional area and the right diaphragm thickness, as well as their echo densities were assessed within 24 h from ICU admission and on day 7. We recorded anthropometric and biochemical data, respiratory mechanics and gas exchange, daily fluid balance, and the number of calories and proteins administered.

RESULTS

Twenty-eight patients were analyzed (65 ± 10 y of age; 80% men, body mass index 30 ± 7.8 kg/m²). Rectus femoris and diaphragm sizes were significantly reduced at day 7 (median = -26.1 [interquartile ratio [IQR], = -37.8 to -15.2] and -29.2% [-37.8% to -19.6%], respectively) and this reduction was significantly higher in non-survivors. Both rectus femoris and diaphragm echo density were significantly increased at day 7, with a significantly higher increase in non-survivors. The change in both rectus femoris and diaphragm size at day 7 was related to the cumulative protein deficit (R = 0.664, P < 0.001 and R = 0.640, P < 0.001, respectively), whereas the change in rectus femoris and diaphragm echo density was related to the cumulative fluid balance (R = 0.734, P < 0.001 and R = 0.646, P < 0.001, respectively).

CONCLUSIONS

Early changes in muscle size and quality seem related to the outcome of critically ill COVID-19 patients, and to be influenced by nutritional and fluid management strategies.

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.

The Importance of the Posterolateral Area of the Diaphragm Muscle for Palpation and for the Treatment of Manual Osteopathic Medicine

The eupneic act in healthy subjects involves a coordinated combination of functional anatomy and neurological activation. Neurologically, a central pattern generator, the components of which are distributed between the brainstem and the spinal cord, are hypothesized to drive the process and are modeled mathematically. A functionally anatomical approach is easier to understand although just as complex. Osteopathic manipulative treatment (OMT) is part of osteopathic medicine, which has many manual techniques to approach the human body, trying to improve the patient's homeostatic response. The principle on which OMT is based is the stimulation of self-healing processes, researching the intrinsic physiological mechanisms of the person, taking into consideration not only the physical aspect, but also the emotional one and the context in which the patient lives. This article reviews how the diaphragm muscle moves, with a brief discussion on anatomy and the respiratory neural network. The goal is to highlight the critical issues of OMT on the correct positioning of the hands on the posterolateral area of the diaphragm around the diaphragm, trying to respect the existing scientific anatomical-physiological data, and laying a solid foundation for improving the data obtainable from future research. The correctness of the position of the operator's hands in this area allows a more effective palpatory perception and, consequently, a probably more incisive result on the respiratory function.

Ultrasound diaphragmatic excursion during non-invasive ventilation in ICU: a prospective observational study

Background and Aim:

Diaphragmatic dysfunction is seen in up to 60% of critically ill patients with respiratory failure, and it is associated with worse outcomes. The functionality of the diaphragm can be studied with simple and codified bedside ultrasound evaluation. Diaphragm excursion is one of the most studied parameters. The aim of this study was to assess the prevalence of diaphragmatic dysfunction in critically ill non-intubated patients admitted to a general intensive care unit with acute respiratory failure.

Methods:

We collected data, including ultrasound diaphragm excursion, at 2 time points: at T0 (at the time of recruitment, just before starting NIV) and at T1 (after one hour of NIV).

Results:

A total of 47 patients were enrolled. The prevalence of diaphragm dysfunction was 42.5% (95% CI 28, 3 - 57,8). Surgical patients showed a higher incidence (relative risk of 1.97) than medical patients. Mean DE was not significantly different between NIV responders (1,35 ± 0.78 cm) and non-responders (1.21 ± 0.85 cm, p 0,6). Patients with diaphragmatic dysfunction responded positively to NIV in 60% (95% CI 36.0 - 80.9%) of cases, while patients without diaphragmatic dysfunction responded positively to the NIV trial in 70.4% (95% CI 49.8 - 86.2%) of cases (p = 0.54). Taking the use of ultrasound diaphragm excursion as a potential predictor of NIV response, the corresponding ROC curve had an area under the curve of 0.53; the best balance between sensitivity (58.1%) and specificity (62.5%) was obtained with a cut-off diaphragm excursion of 1.37 cm.

Conclusions:

Diaphragm dysfunction is particularly frequent in critically ill patients with respiratory failure. The functionality of the diaphragm can be effectively and easily tested by bedside ultrasound examination. Overall, our results point towards tentative evidence of a trend of a different response to NIV in patients with vs without diaphragmatic dysfunction. (www.actabiomedica.it)

Ultrasound and non-ultrasound imaging techniques in the assessment of diaphragmatic dysfunction

Diaphragm muscle dysfunction is increasingly recognized as an important element of several diseases including neuromuscular disease, chronic obstructive pulmonary disease and diaphragm dysfunction in critically ill patients. Functional evaluation of the diaphragm is challenging. Use of volitional maneuvers to test the diaphragm can be limited by patient effort. Non-volitional tests such as those using neuromuscular stimulation are technically complex, since the muscle itself is relatively inaccessible. As such, there is a growing interest in using imaging techniques to characterize diaphragm muscle dysfunction. Selecting the appropriate imaging technique for a given clinical scenario is a critical step in the evaluation of patients suspected of having diaphragm dysfunction. In this review, we aim to present a detailed analysis of evidence for the use of ultrasound and non-ultrasound imaging techniques in the assessment of diaphragm dysfunction. We highlight the utility of the qualitative information gathered by ultrasound imaging as a means to assess integrity, excursion, thickness, and thickening of the diaphragm. In contrast, quantitative ultrasound analysis of the diaphragm is marred by inherent limitations of this technique, and we provide a detailed examination of these limitations. We evaluate non-ultrasound imaging modalities that apply static techniques (chest radiograph, computerized tomography and magnetic resonance imaging), used to assess muscle position, shape and dimension. We also evaluate non-ultrasound imaging modalities that apply dynamic imaging (fluoroscopy and dynamic magnetic resonance imaging) to assess diaphragm motion. Finally, we critically review the application of each of these techniques in the clinical setting when diaphragm dysfunction is suspected.

Central venous pressure swing outperforms diaphragm ultrasound as a measure of inspiratory effort during pressure support ventilation in COVID-19 patients

Purpose

The COVID-19-related shortage of ICU beds magnified the need of tools to properly titrate the ventilator assistance. We investigated whether bedside-available indices such as the ultrasonographic changes in diaphragm thickening ratio (TR) and the tidal swing in central venous pressure (ΔCVP) are reliable estimates of inspiratory effort, assessed as the tidal swing in esophageal pressure (ΔPes).

Methods

Prospective, observational clinical investigation in the intensive care unit of a tertiary care Hospital. Fourteen critically-ill patients were enrolled (age 64 ± 7 years, BMI 29 ± 4 kg/m²), after 6 [3; 9] days from onset of assisted ventilation. A three-level pressure support trial was performed, at 10 (PS10), 5 (PS5) and 0 cmH₂O (PS0). In each step, the esophageal and central venous pressure tidal swing were recorded, as well as diaphragm ultrasound.

Results

The reduction of pressure support was associated with an increased respiratory rate and a reduced tidal volume, while minute ventilation was unchanged. ΔPes significantly increased with reducing support (5 [3; 8] vs. 8 [14; 13] vs. 12 [6; 16] cmH₂O, p < 0.0001), as did the diaphragm TR (9.2 ± 6.1 vs. 17.6 ± 7.2 vs. 28.0 ± 10.0%, p < 0.0001) and the ΔCVP (4 [3; 7] vs. 8 [5; 9] vs. 10 [7; 11] cmH₂O, p < 0.0001). ΔCVP was significantly associated with ΔPes (R² = 0.810, p < 0.001), as was diaphragm TR, albeit with a lower coefficient of determination (R² = 0.399, p < 0.001).

Conclusions

In patients with COVID-19-associated respiratory failure undergoing assisted mechanical ventilation, ΔCVP is a better estimate of inspiratory effort than diaphragm ultrasound.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10877-021-00674-4.

The effect of high-flow nasal cannula on diaphragm dysfunction including paradoxical diaphragmatic contraction in the intensive care unit

Background : Diaphragm dysfunction is a serious problem. However, a few management techniques exist for diaphragm dysfunction. Methods : Adult patients treated with high-flow nasal cannula (HFNC) in the intensive care unit were included in this study. The diaphragm function was evaluated using ultrasound measurement of thickening fraction before and after HFNC liberation. Normal diaphragm contraction was defined as thickening fraction ≥ 15% without HFNC, whereas decreased or paradoxical diaphragm contractions were 0%-15% or < 0%, respectively. Results : Forty patients were enrolled, and 16 (40%) had normal diaphragm contraction, whereas 19 (48%) or 5 (13%) had decreased or paradoxical diaphragm contractions, respectively. Thickening fraction increased after HFNC liberation (27.0% ± 25.7% vs. 38.8% ± 34.5%,  p = 0.03 in HFNC vs. no HFNC) in patients without diaphragm dysfunction. In patients with decreased diaphragm contraction, thickening fraction did not change with or without HFNC (8.9% ± 11.7% vs. 6.7% ± 5.2%,  p = 0.35), whereas paradoxical contraction decreased with HFNC (1.0% ± 10.2% vs. -10.3% ± 2.7%,  p = 0.04) in patients with paradoxical diaphragm contraction. Conclusions : The work of breathing decreased with HFNC in patients without diaphragm dysfunction, but did not decrease in patients with decreased diaphragm contraction. Paradoxical diaphragm contraction decreased with HFNC. J. Med. Invest. 68 : 159-164, February, 2021.

Ultrasonographic assessment of parasternal intercostal muscles during mechanical ventilation

Although mechanical ventilation is a lifesaving treatment, abundant evidence indicates that its prolonged use (1 week or more) promotes respiratory muscle weakness due to both contractile dysfunction and atrophy. Along with the diaphragm, the intercostal muscles are one of the most important groups of respiratory muscles. In recent years, muscular ultrasound has become a useful bedside tool for the clinician to identify patients with respiratory muscle dysfunction related to critical illness and/or invasive mechanical ventilation. Images obtained over the course of illness can document changes in muscle dimension and can be used to estimate changes in function. Recent evidence suggests the clinical usefulness of ultrasound imaging in the assessment of intercostal muscle function. In this narrative review, we summarize the current literature on ultrasound imaging of the parasternal intercostal muscles as used to assess the extent of muscle activation and muscle weakness and its potential impact during discontinuation of mechanical ventilation. In addition, we proposed a practical flowchart based on recent evidence and experience of our group that can be applied during the weaning phase. This approach integrates multiple predictive parameters of weaning success with respiratory muscle ultrasound.

A prospective observational study on critically ill children with diaphragmatic dysfunction: clinical outcomes and risk factors

Background

Diaphragmatic dysfunction (DD) has a great negative impact on clinical outcomes, and it is a well-recognized complication in adult patients with critical illness. However, DD is largely unexplored in the critically ill pediatric population. The aim of this study was to identify risk factors associated with DD, and to investigate the effects of DD on clinical outcomes among critically ill children.

Methods

Diaphragmatic function was assessed by diaphragm ultrasound. According to the result of diaphragmatic ultrasound, all enrolled subjects were categorized into the DD group (n = 24) and the non-DD group (n = 46). Collection of sample characteristics in both groups include age, sex, height, weight, primary diagnosis, complications, laboratory findings, medications, ventilatory time and clinical outcomes.

Results

The incidence of DD in this PICU was 34.3%. The level of CRP at discharge (P = 0.003) in the DD group was higher than the non-DD group, and duration of elevated C-reactive protein (CRP) (P < 0.001), sedative days (P = 0.008) and ventilatory treatment time (P < 0.001) in the DD group was significantly longer than the non-DD group. Ventilatory treatment time and duration of elevated CRP were independently risk factors associated with DD. Patients in the DD group had longer PICU length of stay, higher rate of weaning or extubation failure and higher mortality.

Conclusion

DD is associated with poorer clinical outcomes in critically ill childern, which include a longer PICU length of stay, higher rate of weaning or extubation failure and a higher mortality. The ventilatory treatment time and duration of elevated CRP are main risk factors of DD in critically ill children.

Trial registration

Current Controlled Trials ChiCTR1800020196, Registered 01 Dec 2018.

Oesophageal pressure and respiratory muscle ultrasonographic measurements indicate inspiratory effort during pressure support ventilation

BACKGROUND

Bedside measures of patient effort are essential to properly titrate the level of pressure support ventilation. We investigated whether the tidal swing in oesophageal (ΔPes) and transdiaphragmatic pressure (ΔPdi), and ultrasonographic changes in diaphragm (TFdi) and parasternal intercostal (TFic) thickening are reliable estimates of respiratory effort. The effect of diaphragm dysfunction was also considered.

METHODS

Twenty-one critically ill patients were enrolled: age 73 (14) yr, BMI 27 (7) kg m^-2, and Pao₂/Fio₂ 33.3 (9.2) kPa. A three-level pressure support trial was performed: baseline, 25% (PS-medium), and 50% reduction (PS-low). We recorded the oesophageal and transdiaphragmatic pressure-time products (PTPs), work of breathing (WOB), and diaphragm and intercostal ultrasonography. Diaphragm dysfunction was defined by the Gilbert index.

RESULTS

Pressure support was 9.0 (1.6) cm H₂O at baseline, 6.7 (1.3) (PS-medium), and 4.4 (1.0) (PS-low). ΔPes was significantly associated with the oesophageal PTP (R²=0.868; P<0.001) and the WOB (R²=0.683; P<0.001). ΔPdi was significantly associated with the transdiaphragmatic PTP (R²=0.820; P<0.001). TFdi was only weakly correlated with the oesophageal PTP (R²=0.326; P<0.001), and the correlation improved after excluding patients with diaphragm dysfunction (R²=0.887; P<0.001). TFdi was higher and TFic lower in patients without diaphragm dysfunction: 33.6 (18.2)% vs 13.2 (9.2)% and 2.1 (1.7)% vs 12.7 (9.1)%; P<0.0001.

CONCLUSIONS

ΔPes and ΔPdi are adequate estimates of inspiratory effort. Diaphragm ultrasonography is a reliable indicator of inspiratory effort in the absence of diaphragm dysfunction. Additional measurement of parasternal intercostal thickening may discriminate a low inspiratory effort or a high effort in the presence of a dysfunctional diaphragm.

Does it make difference to measure diaphragm function with M mode (MM) or B mode (BM)?

Diaphragm dysfunction occurs in mechanically ventilated subjects. Recent literature suggests that diaphragm thickening fraction (DTF) measured by ultrasound can be useful to predict weaning outcome. However, there is no standardized approach in the measurement of diaphragm thickness (DT) and limited data exists comparing different measurement techniques of diaphragm thickness (M mode-MM or B mode-BM). The goal of this study was to compare MM with BM in the measurements of DT and excursion in the ICU subjects. DT measurements were obtained from the right diaphragm during tidal and maximal inspiratory breathing. Three measurements of the DT were taken both in MM and BM and their mean values were calculated. DT was measured during inspiration and expiration and DTF was calculated. Excursion of diaphragm was also measured with MM and BM during tidal and maximal inspiratory breathing. Bias and agreement between the two measurement methods were evaluated with Bland and Altman test. Sixty-two subjects were enrolled in the study. While 25 (40%) subjects were receiving invasive mechanical ventilation, 14 (23%) subjects ventilated noninvasively. There were no significant difference between the measurement results of MM and BM. BM and MM tidal diaphragm measurements during the inspiratory (0.3 ± 0.08 and 0.31 ± 0.08 cm; P = 0.022), expiratory (0.24 ± 0.07 and 0.24 ± 0.07 cm; P = 0.315) phases and tidal DTF were (27 ± 16 and 31 ± 14%, P = 0.089) respectively. Results of our study suggests that except tidal inspiratory diaphragm thickness, all thickness and excursion measurements with MM and BM are very compatible with each other. Further studies are necessarry to confirm our results and to standardize the measurements of diaphragm.

Neuromuscular Ultrasound: Clinical Applications and Diagnostic Values

Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.

Severe diaphragmatic dysfunction with preserved activity of accessory respiratory muscles in a critically ill child: a case report of failure of neurally adjusted ventilatory assist (NAVA) and successful support with pressure support ventilation (PSV)

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is an alternative to pressure support ventilation (PSV) potentially improving patient-ventilator interaction. During NAVA, diaphragmatic electrical activity (EAdi) is used to trigger the ventilator and perform a proportional respiratory assistance. We present a case in which the presence of severe bilateral diaphragmatic dysfunction led to a failure of NAVA. On the contrary, the preserved activity of the accessory inspiratory muscles allowed a successful respiratory assistance using PSV.

CASE PRESENTATION

A 10-year-old girl developed quadriplegia after neurological surgery. Initially, no spontaneous breathing activity was present and volume controlled ventilation was necessary. Two months later spontaneous inspiratory efforts were observed and a maximal negative inspiratory force of - 20 cmH₂O was recorded. In addition, a NAVA nasogastric tube was placed. The recorded EAdi signal, despite showing a phasic activity, had a very low amplitude (1-2 μV). Two brief (15 min) breathing trials to compare PSV (pressure support = 8 cmH₂O) with NAVA (Gain = 5 cmH₂O/μV, inspiratory trigger = 0.3 μV) were performed. On PSV, the patient was well adapted with stable tidal volumes, respiratory rates, minute ventilation, end-tidal and venous carbon dioxide levels. When switched to NAVA, her breathing pattern became irregular and she showed clear sign of increased work of breathing and distress: tidal volume dropped and respiratory rate rose, leading to an increase in total minute ventilation. Nevertheless, end-tidal and venous carbon dioxide rapidly increased (from 49 to 55 mmHg and from 52 to 57 mmHg, respectively). An electromyographic study documented an impairment of the diaphragm with preserved activity of the accessory inspiratory muscles.

CONCLUSIONS

We document the failure of mechanical assistance performed with NAVA due to bilateral diaphragmatic dysfunction in a critically ill child. The preserved activity of some accessory respiratory muscles allowed to support the patient effectively with pressure support ventilation, i.e. by applying a pneumatic trigger. The present case underlines (i) the importance of the integrity of the respiratory centers, phrenic nerves and diaphragm in order to perform NAVA and (ii) the possible diagnostic role of EAdi monitoring in complex cases of weaning failure.

Disorders of the Diaphragm

Pathologic processes that involve the central nervous system, phrenic nerve, neuromuscular junction, and skeletal muscle can impair diaphragm function. When these processes are of sufficient severity to cause diaphragm dysfunction, respiratory failure may be a consequence. This article reviews basic diaphragm anatomy and physiology and then discusses diagnostic and therapeutic approaches to disorders that result in unilateral or bilateral diaphragm dysfunction. This discussion provides a context in which disorders of the diaphragm and their implications on respiratory function can be better appreciated.

Respiratory and Peripheral Muscle Assessment in the Intensive Care Unit

Atrophy and weakness of the respiratory and peripheral muscles is a common problem in the intensive care unit (ICU). It is difficult to diagnose, particularly in the early stages of critical disease. Consequently, many cases are detected only in advanced stages, for example, when difficulties in mechanical ventilation weaning are encountered. The aim of this review is to describe the main tools that are currently available for evaluation of peripheral and respiratory muscles in the ICU. Techniques of varying complexity and specificity are discussed, and particular emphasis is placed on those with greater relevance in daily clinical practice, such as ultrasound.

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.

Lung and diaphragm ultrasound as predictors of success in weaning from mechanical ventilation

BACKGROUND

Lung and diaphragm ultrasound methods have recently been introduced to predict the outcome of weaning from mechanical ventilation (MV). The aim of this study is to assess the reliability and accuracy of these techniques for predicting successful weaning in critically ill adults.

METHODS

We conducted two studies: a cross-sectional interobserver agreement study between two sonographers and a prospective cohort study to assess the accuracy of lung and diaphragm ultrasound for predicting weaning and extubation outcome. For the interobserver agreement study, we included 50 general critical care patients who were consecutively admitted to the ICU. For the predictive accuracy study, we included consecutively 69 patients on MV who were ready for weaning. We assessed interobserver agreement of ultrasound measurements, using the weighted kappa coefficient for LUSm score (modified lung ultrasound score) and the intraclass correlation coefficient (ICC) and Bland-Altman method for TI (diaphragm thickening index). We assessed the predictive value of LUSm and TI in weaning outcome by plotting the corresponding ROC curves.

RESULTS

We found adequate interobserver agreement for both LUSm (weighted kappa 0.95) and TI (ICC 0.78, difference according to Bland-Altman analysis ± 12.5%). LUSm showed good-moderate discriminative power for successful weaning and extubation (area under the ROC curve (AUC) for successful weaning 0.80, and sensitivity and specificity at optimal cut-off point 0.76 and 0.73, respectively; AUC for successful extubation 0.78, and optimal sensitivity and specificity 0.76 and 0.47, respectively. TI was more sensitive but less specific for predicting successful weaning (AUC 0.71, optimal sensitivity and specificity 0.93 and 0.48) and successful extubation (AUC 0.76, optimal sensitivity and specificity 0.93 and 0.58). The area under the ROC curve for predicting weaning success was 0.83 for both ultrasound measurements together.

CONCLUSIONS

Interobserver agreement was excellent for LUSm and moderate-good for TI. A low TI value or high LUSm value indicates high risk of weaning failure.

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.

Respiratory failure because of neuromuscular disease

PURPOSE OF REVIEW

Understanding the mechanisms and abnormalities of respiratory function in neuromuscular disease is critical to supporting the patient and maintaining ventilation in the face of acute or chronic progressive impairment.

RECENT FINDINGS

Retrospective clinical studies reviewing the care of patients with Guillain-Barré syndrome and myasthenia have shown a disturbingly high mortality following step-down from intensive care. This implies high dependency and rehabilitation management is failing despite evidence that delayed improvement can occur with long-term care. A variety of mechanisms of phrenic nerve impairment have been recognized with newer investigation techniques, including EMG and ultrasound. Specific treatment for progressive neuromuscular and muscle disease has been increasingly possible particularly for the treatment of myasthenia, metabolic myopathies, and Duchenne muscular dystrophy. For those conditions without specific treatment, it has been increasingly possible to support ventilation in the domiciliary setting with newer techniques of noninvasive ventilation and better airway clearance. There remained several areas of vigorous debates, including the role for tracheostomy care and the place of respiratory muscle training and phrenic nerve/diaphragm pacing.

SUMMARY

Recent studies and systematic reviews have defined criteria for anticipating, recognizing, and managing ventilatory failure because of acute neuromuscular disease. The care of patients requiring long-term noninvasive ventilatory support for chronic disorders has also evolved. This has resulted in significantly improved survival for patients requiring domiciliary ventilatory support.

Diaphragm Dysfunction in Critical Illness

The diaphragm is the major muscle of inspiration, and its function is critical for optimal respiration. Diaphragmatic failure has long been recognized as a major contributor to death in a variety of systemic neuromuscular disorders. More recently, it is increasingly apparent that diaphragm dysfunction is present in a high percentage of critically ill patients and is associated with increased morbidity and mortality. In these patients, diaphragm weakness is thought to develop from disuse secondary to ventilator-induced diaphragm inactivity and as a consequence of the effects of systemic inflammation, including sepsis. This form of critical illness-acquired diaphragm dysfunction impairs the ability of the respiratory pump to compensate for an increased respiratory workload due to lung injury and fluid overload, leading to sustained respiratory failure and death. This review examines the presentation, causes, consequences, diagnosis, and treatment of disorders that result in acquired diaphragm dysfunction during critical illness.

A randomized clinical trial of neurally adjusted ventilatory assist versus conventional weaning mode in patients with COPD and prolonged mechanical ventilation

BACKGROUND

Patient-ventilator asynchrony is a common problem in mechanically ventilated patients; the problem is especially obvious in COPD. Neutrally adjusted ventilatory assist (NAVA) can improve patient-ventilator asynchrony; however, the effect in COPD patients with prolonged mechanical ventilation is still unknown. The goals of this study are to evaluate the effect of NAVA and conventional weaning mode in patients with COPD during prolonged mechanical ventilation.

METHODS

The study enrolled a total of 33 COPD patients with ventilator dependency for more than 21 days in the weaning center. A diaphragm electrical activity (Edi) catheter was inserted in patients within 24 hours after admission to the respiratory care center, and patients were randomly allocated to NAVA or conventional group. A spontaneous breathing trial was performed every 24 hours. The results correlated with the clinical parameters.

RESULTS

There were significantly higher asynchrony incidence rates in the whole group after using Edi catheter (before vs post-Edi catheter insertion =60.6% vs 87.9%, P<0.001). Asynchrony index: before vs post-Edi catheter insertion =7.4%±8.5% vs 13.2%±13.5%, P<0.01. Asynchrony incidence: NAVA vs conventional =0% vs 84.2%, P<0.001. Asynchrony index: NAVA vs conventional =0 vs 11.9±11.2 (breath %), P<0.001. The most common asynchrony events were ineffective trigger and delayed trigger.

CONCLUSION

Compared to conventional mode, NAVA mode can significantly enhance respiratory monitoring and improve patient-ventilator interaction in COPD patients with prolonged mechanical ventilation in respiratory care center.