Sonographic evaluation of the diaphragm in critically ill patients. Technique and clinical applications

The Application of Diaphragm Ultrasound in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic Obstructive Pulmonary Disease (COPD) is a prevalent condition that poses a significant burden on individuals and society due to its high morbidity and mortality rates. The diaphragm is the main respiratory muscle, its function has a direct impact on the quality of life and prognosis of COPD patients. This article aims to review the structural measurement and functional evaluation methods through the use of diaphragmatic ultrasound and relevant research on its application in clinical practice for COPD patients. Thus, it serves to provide valuable insights for clinical monitoring of diaphragm function in COPD patients, facilitating early clinical intervention and aiding in the recovery of diaphragm function.

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

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

Operator independent continuous ultrasound monitoring of diaphragm excursion predicts successful weaning from mechanical ventilation: a prospective observational study

BACKGROUND

In mechanically ventilated patients, diaphragm ultrasound can identify diaphragm weakness and predict weaning failure. We evaluated whether a novel operator-independent ultrasound-based medical device allowing continuous monitoring of the diaphragm (CUSdi) could reliably (1) measure diaphragm excursion (EXdi) and peak contraction velocity (PCVdi), (2) predict weaning outcome, and (3) approximate transdiaphragmatic pressure (Pdi).

METHODS

In 49 mechanically ventilated patients, CUSdi was recorded during a 30-min spontaneous breathing trial (SBT), and EXdi and PCVdi were measured. In subgroups of patients, standard ultrasound measurement of EXdi and PCVdi was performed (n = 36), and Pdi derived parameters (peak and pressure time product, n = 30) were measured simultaneously.

RESULTS

The agreement bias between standard ultrasound and CUSdi for EXdi was 0.1 cm (95% confidence interval -0.7-0.9 cm). The regression of Passing-Bablok indicated a lack of systematic difference between EXdi measured with standard ultrasound and CUSdi, which were positively correlated (Rho = 0.84, p < 0.001). Weaning failure was observed in 54% of patients. One, two and three minutes after the onset of the SBT, EXdi was higher in the weaning success group than in the failure group. Two minutes after the onset of the SBT, an EXdi < 1.1 cm predicted weaning failure with a sensitivity of 0.83, a specificity of 0.68, a positive predictive value of 0.76, and a negative predictive value of 0.24. There was a weak correlation between EXdi and both peak Pdi (r = 0.22, 95% confidence interval 0.15 - 0.28) and pressure time product (r = 0.13, 95% confidence interval 0.06 - 0.20). Similar results were observed with PCVdi.

CONCLUSIONS

Operator-independent continuous diaphragm monitoring quantifies EXdi reliably and can predict weaning failure with an identified cut-off value of 1.1 cm. Trial registration clinicaltrial.gov, NCT04008875 (submitted 12 April 2019, posted 5 July 2019) and NCT03896048 (submitted 27 March 2019, posted 29 March 2019).

Ultrasonographic measurement of diaphragm muscle activity for assessment of respiratory function in horses

Ultrasonographic imaging of the diaphragm is a non-invasive alternative for respiratory function evaluation in horses. This study aimed to measure diaphragm thickness, thickening (change in thickness with contraction) and thickening fraction in healthy adult horses during tidal breathing and forced vital capacity. Correlation between body weight (≤400 kg and >400 kg) and diaphragm thickness was investigated. To that purpose, 20 adult horses, weight 409±50 kg, height 1.47±0.05 m, and age 16±6 years were included in the study. Diaphragm thickness was measured at end-inspiration and end-expiration using B-mode and M-mode. The transducer was placed in the 10th, 11th and 12th intercostal spaces of both hemithoraces. Measurements obtained at end inspiration using M-mode during forced vital capacity were greater than for tidal breathing for diaphragm thickness (P=0.006), diaphragm thickening (P<0.001) and thickening fraction (P<0.001). The same was found for thickening (P<0.001) and thickening fraction (P<0.001). Diaphragm thickness at end-inspiration was greater in horses weighing >400kg than those ≤400kg at the inspiration (0.93±0.2 cm and 0.74±0 0.02 cm, P<0.001) and at the end of expiration (0.77±0.02 cm and 0.63±0, 02 cm, P<0.001). There was no difference in thickening fraction between horses weighing ≤400kg and >400kg (tidal breathing: 18±2 % and 16±2 %, P=0.609; forced vital capacity: 39±6 % and 31±5 %, P=0.301). Diaphragm assessment in horses is possible using both B-mode and M-mode. Breathing workload has a positive correlation between breathing workload and diaphragm contraction. Due to the relationship demonstrated between diaphragm thickness and weight, it is recommended that diaphragm thickening fraction is used to compare diaphragm measurements between horses.

Effect of high-flow nasal cannula at different flow rates on diaphragmatic function in subjects recovering from an acute exacerbation of COPD: a physiological prospective pilot study

BACKGROUND

Noninvasive ventilation (NIV) is widely employed as the initial treatment for patients with chronic acute exacerbation of obstructive pulmonary disease (AECOPD). Nevertheless, high-flow nasal cannula (HFNC) has been increasingly utilized and investigated to mitigate the issues associated with NIV. Flow rate may play a significant role in diaphragmatic function among subjects recovering from AECOPD. Based on these observations, we conducted a physiological study to assess the impact of HFNC therapy on diaphragmatic function, as measured by US, respiratory rate (RR), gas exchange, and patient comfort at various flow rates.

METHODS

A prospective physiological pilot study enrolled subjects with a diagnosis of AECOPD who required NIV for more than 24 h. After stabilization, these subjects underwent a 30-min trial using NIV and HFNC at different sequential flow rates (30-60 L/min). At the end of each trial, diaphragmatic displacement (DD, cm) and diaphragmatic thickness fraction (DTF, %) were measured using ultrasound. Additionally, other physiological variables, such as RR, gas exchange, and patient comfort, were recorded.

RESULTS

A total of 20 patients were included in the study. DD was no different among trials (p = 0.753). DTF (%) was significantly lower with HFNC-30 L/min compared to HFNC-50 and 60 L/min (p < 0.001 for all comparisons). No significant differences were found in arterial pH and PaCO2 at discontinuation of NIV and at the end of HFNC trials (p > 0.050). During HFNC trials, RR remained unchanged without statistically significant differences (p = 0.611). However, we observed that HFNC improved comfort compared to NIV (p < 0.001 for all comparisons). Interestingly, HFNC at 30 and 40 L/min showed greater comfort during trials.

CONCLUSIONS

In subjects recovering from AECOPD and receiving HFNC, flows above 40 L/min may not offer additional benefits in terms of comfort and decreased respiratory effort. HFNC could be a suitable alternative to COT during breaks off NIV.

Ultrasound assessment of diaphragmatic dysfunction in non-critically ill patients: relevant indicators and update

Diaphragm dysfunction (DD) can be classified as mild, resulting in diaphragmatic weakness, or severe, resulting in diaphragmatic paralysis. Various factors such as prolonged mechanical ventilation, surgical trauma, and inflammation can cause diaphragmatic injury, leading to negative outcomes for patients, including extended bed rest and increased risk of pulmonary complications. Therefore, it is crucial to protect and monitor diaphragmatic function. Impaired diaphragmatic function directly impacts ventilation, as the diaphragm is the primary muscle involved in inhalation. Even unilateral DD can cause ventilation abnormalities, which in turn lead to impaired gas exchange, this makes weaning from mechanical ventilation challenging and contributes to a higher incidence of ventilator-induced diaphragm dysfunction and prolonged ICU stays. However, there is insufficient research on DD in non-ICU patients, and DD can occur in all phases of the perioperative period. Furthermore, the current literature lacks standardized ultrasound indicators and diagnostic criteria for assessing diaphragmatic dysfunction. As a result, the full potential of diaphragmatic ultrasound parameters in quickly and accurately assessing diaphragmatic function and guiding diagnostic and therapeutic decisions has not been realized.

Automatic Quantitative Assessment of Muscle Strength Based on Deep Learning and Ultrasound

Skeletal muscle is a vital organ that promotes human movement and maintains posture. Accurate assessment of muscle strength is helpful to provide valuable insights for athletes' rehabilitation and strength training. However, traditional techniques rely heavily on the operator's expertise, which may affect the accuracy of the results. In this study, we propose an automated method to evaluate muscle strength using ultrasound and deep learning techniques. B-mode ultrasound data of biceps brachii of multiple athletes at different strength levels were collected and then used to train our deep learning model. To evaluate the effectiveness of this method, this study tested the contraction of the biceps brachii under different force levels. The classification accuracy of this method for grade 4 and grade 6 muscle strength reached 98% and 96%, respectively, and the overall average accuracy was 93% and 87%, respectively. The experimental results confirm that the innovative methods in this paper can accurately and effectively evaluate and classify muscle strength.

Fetal Diaphragmatic Excursion Is Decreased in Hospitalized Pregnant Women Infected with COVID-19 during the Second and Third Trimesters

OBJECTIVE

 In the present study, we aimed to evaluate coronavirus disease 2019 (COVID-19) infection effects on fetal diaphragm thickness and diaphragmatic excursion, which together show the quality of diaphragmatic contractions.

STUDY DESIGN

 One hundred and ninety-two pregnant women were included in this prospective case-control study. Patients were divided into four groups according to their COVID-19 infection history in their second or third trimester: hospitalized COVID-19-infected pregnant women group (n = 48), outpatient COVID-19-infected pregnant women group (n = 48), common cold (COVID-19 polymerase chain reaction negative) pregnant women group (n = 48), and noninfected healthy controls (n = 48). The number of patients was determined by power analysis following the pilot study. All participants underwent an ultrasound examination to determine fetal diaphragm parameters at 32 to 37 weeks of gestation.

RESULTS

 Demographic characteristics were similar among the four groups. The gestational age at ultrasound examination and gestational age at delivery were similar among the groups. Neonatal intensive care unit (NICU) admission rate was significantly higher in the hospitalized COVID-19-infected pregnant women group than the other groups. The fetal diaphragm thickness during inspiration and expiration, and fetal costophrenic angles at inspiration and expiration were similar among the groups. Fetal diaphragmatic excursion was significantly decreased in the hospitalized COVID-19-infected pregnant women group compared with the other groups.

CONCLUSION

 Our results indicated that moderate maternal COVID-19 infection decreased fetal diaphragmatic excursion, and ultrasonographic evaluation of fetal diaphragmatic excursion before delivery can provide critical information to predict whether infants will require NICU admission.

KEY POINTS

· Diaphragm ultrasound as a new technique for characterizing the diaphragm's structure and function.. · Fetal diaphragmatic excursion is decreased in the presence of moderate COVID-19 infection.. · Ultrasonographic evaluation of fetal diaphragmatic excursion provides critical information to predict NICU admission..

Combined cardiac, lung, and diaphragm ultrasound for predicting weaning failure during spontaneous breathing trial

BACKGROUND

Weaning from invasive mechanical ventilation (MV) is a complex and challenging process that involves multiple pathophysiological mechanisms. A combined ultrasound evaluation of the heart, lungs, and diaphragm during the weaning phase can help to identify risk factors and underlying mechanisms for weaning failure. This study aimed to investigate the accuracy of lung ultrasound (LUS), transthoracic echocardiography (TTE), and diaphragm ultrasound for predicting weaning failure in critically ill patients.

METHODS

Patients undergoing invasive MV for > 48 h and who were readied for their first spontaneous breathing trial (SBT) were studied. Patients were scheduled for a 2-h SBT using low-level pressure support ventilation. LUS and TTE were performed prospectively before and 30 min after starting the SBT, and diaphragm ultrasound was only performed 30 min after starting the SBT. Weaning failure was defined as failure of SBT, re-intubation, or non-invasive ventilation within 48 h.

RESULTS

Fifty-one patients were included, of whom 15 experienced weaning failure. During the SBT, the global, anterior, and antero-lateral LUS scores were higher in the failed group than in the successful group. Receiver operating characteristic curve analysis showed that the areas under the curves for diaphragm thickening fraction (DTF) and global and antero-lateral LUS scores during the SBT to predict weaning failure were 0.678, 0.719, and 0.721, respectively. There was no correlation between the LUS scores and the average E/e' ratio during the SBT. Multivariate analysis identified antero-lateral LUS score > 7 and DTF < 31% during the SBT as independent predictors of weaning failure.

CONCLUSION

LUS and diaphragm ultrasound can help to predict weaning failure in patients undergoing an SBT with low-level pressure support. An antero-lateral LUS score > 7 and DTF < 31% during the SBT were associated with weaning failure.

Effects of robotic-assisted early mobilization versus conventional mobilization in intensive care unit patients: prospective interventional cohort study with retrospective control group analysis

BACKGROUND

Approximately one in three survivors of critical illness suffers from intensive-care-unit-acquired weakness, which increases mortality and impairs quality of life. By counteracting immobilization, a known risk factor, active mobilization may mitigate its negative effects on patients. In this single-center trial, the effect of robotic-assisted early mobilization in the intensive care unit (ICU) on patients' outcomes was investigated.

METHODS

We enrolled 16 adults scheduled for lung transplantation to receive 20 min of robotic-assisted mobilization and verticalization twice daily during their first week in the ICU (intervention group: IG). A control group (CG) of 13 conventionally mobilized patients after lung transplantation was recruited retrospectively. Outcome measures included the duration of mechanical ventilation, length of ICU stay, muscle parameters evaluated by ultrasound, and quality of life after three months.

RESULTS

During the first week in the ICU, the intervention group received a median of 6 (interquartile range 3-8) robotic-assisted sessions of early mobilization and verticalization. There were no statistically significant differences in the duration of mechanical ventilation (IG: median 126 vs. CG: 78 h), length of ICU stay, muscle parameters evaluated by ultrasound, and quality of life after three months between the IG and CG.

CONCLUSION

In this study, robotic-assisted mobilization was successfully implemented in the ICU setting. No significant differences in patients' outcomes were observed between conventional and robotic-assisted mobilization. However, randomized and larger studies are necessary to validate the adequacy of robotic mobilization in other cohorts.

TRIAL REGISTRATION

This single-center interventional trial was registered in clinicaltrials.gov as NCT05071248 on 27/08/2021.

The effect of high-flow oxygen via tracheostomy on respiratory pattern and diaphragmatic function in patients with prolonged mechanical ventilation: A randomized, physiological, crossover study

Background

Compared to conventional oxygen devices, high-flow oxygen treatment (HFOT) through the nasal cannulae has demonstrated clinical benefits. Limited data exist on whether such effects are also present in HFOT through tracheostomy. Hence, we aimed to examine the short-term effects of HFOT through tracheostomy on diaphragmatic function and respiratory parameters in tracheostomized patients on prolonged mechanical ventilation.

Methods

A randomized, crossover, physiological study was conducted in our ICU between December 2020 and April 2021, in patients with tracheostomy and prolonged mechanical ventilation. The patients underwent a 30-min spontaneous breathing trial (SBT) and received oxygen either via T-piece or by HFOT through tracheostomy, followed by a washout period of 15-min breathing through the T-piece and receipt of 30-min oxygen with the other modality in a randomized crossover manner. At the start and end of each session, blood gasses, breathing frequency (f), and tidal volume (VT) via a Wright's spirometer were measured, along with diaphragm ultrasonography including diaphragm excursion and diaphragmatic thickening fraction, which expressed the inspiratory muscle effort.

Results

Eleven patients were enrolled in whom 19 sessions were uneventfully completed; eight patients were studied twice on two different days with alternate sessions; and three patients were studied once. Patients were randomly assigned to start the SBT with a T-piece (n=10 sessions) or with HFOT (n=9 sessions). With HFOT, VT and minute ventilation (VE) significantly increased during SBT (from [465±119] mL to [549±134] mL, P <0.001 and from [12.4±4.3] L/min to [13.1±4.2] L/min, P <0.05, respectively), but they did not change significantly during SBT with T-piece (from [495±132] mL to [461±123] mL and from [12.8±4.4] mL to [12.0±4.4] mL, respectively); f/VT decreased during HFOT (from [64±31] breaths/(min∙L) to [49±24] breaths/(min∙L), P <0.001), but it did not change significantly during SBT with T-piece (from [59±28] breaths/(min∙L) to [64±33] breaths/(min∙L)); partial pressure of arterial oxygen increased during HFOT (from [99±39] mmHg to [132±48] mmHg, P <0.001), but it decreased during SBT with T-piece (from [124±50] mmHg to [83±22] mmHg, P <0.01). In addition, with HFOT, diaphragmatic excursion increased (from [12.9±3.3] mm to [15.7±4.4] mm, P <0.001), but it did not change significantly during SBT with T-piece (from [13.4±3.3] mm to [13.6±3.3] mm). The diaphragmatic thickening fraction did not change during SBT either with T-piece or with HFOT.

Conclusion

In patients with prolonged mechanical ventilation, HFOT through tracheostomy compared with T-piece improves ventilation, pattern of breathing, and oxygenation without increasing the inspiratory muscle effort.

Trial Registration

Clinicaltrials.gov ldentifer: NCT04758910.

Diaphragm thickness modifications and associated factors during VA-ECMO for a cardiogenic shock: a cohort study

BACKGROUND

The incidence, causes and impact of diaphragm thickness evolution in veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for cardiogenic shock are unknown. Our study investigates its evolution during the first week of VA-ECMO and its relationship with sweep gas flow settings.

METHODS

We conducted a prospective monocentric observational study in a 12-bed ICU in France, enrolling patients on the day of the VA-ECMO implantation. The diaphragm thickness and the diaphragm thickening fraction (as index of contractile activity, dTF; dTF < 20% defined a low contractile activity) were daily measured for one week using ultrasound. Factors associated with diaphragm thickness evolution (categorized as increased, stable, or atrophic based on > 10% modification from baseline to the last measurement), early extubation role (< day4), and patients outcome at 60 days were investigated. Changes in diaphragm thickness, the primary endpoint, was analysed using a mixed-effect linear model (MLM).

RESULTS

Of the 29 included patients, seven (23%) presented diaphragm atrophy, 18 remained stable (60%) and 4 exhibited an increase (17%). None of the 13 early-extubated patients experienced diaphragm atrophy, while 7 (46%) presented a decrease when extubated later (p-value = 0.008). Diaphragm thickness changes were not associated with the dTF (p-value = 0.13) but with sweep gas flow (Beta = - 3; Confidence Interval at 95% (CI) [- 4.8; - 1.2]. p-value = 0.001) and pH (Beta = - 2; CI [- 2.9; - 1]. p-value < 0.001) in MLM. The dTF remained low (< 20%) in 20 patients (69%) at the study's end and was associated with sweep gas flow evolution in MLM (Beta = - 2.8; 95% CI [- 5.2; - 0.5], p-value = 0.017). Odds ratio of death at 60 days in case of diaphragm atrophy by day 7 was 8.50 ([1.4-74], p = 0.029).

CONCLUSION

In our study, diaphragm thickness evolution was frequent and not associated with the diaphragm thickening fraction. Diaphragm was preserved from atrophy in case of early extubation with ongoing VA-ECMO assistance. Metabolic disorders resulting from organ failures and sweep gas flow were linked with diaphragm thickness evolution. Preserved diaphragm thickness in VA-ECMO survivors emphasizes the importance of diaphragm-protective strategies, including meticulous sweep gas flow titration.

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.

Rapid review of ventilator-induced diaphragm dysfunction

Ventilator-induced diaphragm dysfunction is gaining increased recognition. Evidence of diaphragm weakness can manifest within 12 h to a few days after the initiation of mechanical ventilation. Various noninvasive and invasive methods have been developed to assess diaphragm function. The implementation of diaphragm-protective ventilation strategies is crucial for preventing diaphragm injuries. Furthermore, diaphragm neurostimulation emerges as a promising and novel treatment option. In this rapid review, our objective is to discuss the current understanding of ventilator-induced diaphragm dysfunction, diagnostic approaches, and updates on strategies for prevention and management.

Non-invasive diagnosis of diaphragmatic paralysis in botulism using ultrasound

This case study explores foodborne botulism, a severe illness caused by botulinum neurotoxin-contaminated food. It leads to bilateral descending paralysis, involving the diaphragm. We highlight diaphragmatic ultrasound as a non-invasive diagnostic tool. A 50-year-old obese male developed diplopia and weakness after consuming contaminated food, rapidly progressing to severe symptoms. Mechanical ventilation became necessary due to respiratory failure. Diaphragmatic ultrasound confirmed bilateral diaphragm paralysis despite early antitoxin treatment. The patient experienced complications, requiring tracheostomy and rehabilitation. After five months, he fully recovered diaphragmatic function. This study underscores botulism's life-threatening nature and the vital role of supportive care. Diaphragmatic ultrasound is a safe and effective method for assessing diaphragmatic function in such cases, obviating ionizing radiation exposure. We recommend its routine use for evaluating botulism-induced paralysis.

Thoracic ultrasound use in hospitalized and ambulatory adult patients: a quantitative picture

INTRODUCTION AND OBJECTIVES

Thoracic ultrasound (TUS) has been established as a powerful diagnostic and monitoring tool in the Intensive Care Unit (ICU). However, studies outside the critical care setting are scarce. The aim of this study was to investigate the value of TUS for hospitalized or ambulatory community patients.

MATERIALS AND METHODS

This was a retrospective study conducted from 2016 to 2020 in the TUS clinic at Heraklion University Hospital. TUS examination was performed using a standard ultrasound machine (EUB HITACHI 8500), and a high-frequency microconvex probe (5-8 MHz). Patients had been referred by their primary physician to address a range of different questions. The various respiratory system entities were characterised according to internationally established criteria.

RESULTS

762 TUS studies were performed on 526 patients due to underlying malignancy (n = 376), unexplained symptoms/signs (n = 53), pregnancy related issues (n = 42), evaluation of abnormal findings in X-ray (n = 165), recent surgery/trauma (n = 23), recent onset respiratory failure (n = 12), acute respiratory infection (n = 66) and underlying non-malignant disease (n = 25). Pleural effusion was the commonest pathologic entity (n = 610), followed by consolidation (n = 269), diaphragmatic dysfunction/paradox (n = 174) and interstitial syndrome (n = 53). Discrepancies between chest X-ray and ultrasonographic findings were demonstrated in 96 cases. The TUS findings guided invasive therapeutic management in 448 cases and non-invasive management in 43 cases, while follow-up monitoring was decided in 271 cases.

CONCLUSIONS

This study showed that TUS can identify the most common respiratory pathologic entities encountered in hospitalized and community ambulatory patients, and is especially useful in guiding the decision making process in a diverse group of patients.

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.

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.

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.

Diaphragmatic ultrasonography as a predictor of respiratory muscle fatigue in myasthenia gravis

INTRODUCTION/AIMS

Easy fatigability, the clinical hallmark of generalized myasthenia gravis (GMG), cannot be detected in a dynamic way. The aim of this study was to assess respiratory function dynamically through diaphragmatic ultrasonography (DUS) in GMG patients.

METHODS

GMG patients and controls were recruited in a 1:1 ratio. DUS was performed during one quiet breath and 15 consecutive deep breaths. The diaphragm thicknesses were measured at different positions. Diaphragm thickening fraction (TFdi) and the maximal change in diaphragm thickness (Tmax) during 15 consecutive deep breaths were calculated and transformed to normality, named N-TFdi and N-Tmax, respectively. The percentages of changes in TFdi and Tmax compared with baseline were named ΔTFdi and ΔTmax, respectively. The diagnostic parameter for respiratory muscle fatigue was chosen from ΔTFdi and ΔTmax at different deep breath times according to their ability to distinguish GMG patients from controls and the interrater reliability of TFdi and Tmax.

RESULTS

Thirty-four GMG patients and 30 healthy controls were enrolled. N-TFdi and N-Tmax significantly changed as the number of deep breaths increased (p < .001) in GMG patients, but not in controls. ΔTmax of the 15th deep breath (ΔTmax15) was selected as the diagnostic parameter for respiratory muscle fatigue. There were no significant differences in percentage of predicted values of forced vital capacity and arterial partial pressure of carbon dioxide between patients with normal and abnormal ΔTmax15.

DISCUSSION

DUS could identify diaphragm fatiguability in GMG patients, which may be more reliable and sensitive in assessment of diaphragm fatigue than conventional methods.

Assessment of Pulmonary Circulation of Critically Ill Patients Based on Critical Care Ultrasound

Pulmonary circulation is crucial in the human circulatory system, facilitating the oxygenation of blood as it moves from the right heart to the lungs and then to the left heart. However, during critical illness, pulmonary microcirculation can be vulnerable to both intrapulmonary and extrapulmonary injuries. To assess these potential injuries in critically ill patients, critical point-of-care ultrasound can be used to quantitatively and qualitatively evaluate the right atrium, right ventricle, pulmonary artery, lung, pulmonary vein, and left atrium along the direction of blood flow. This assessment is particularly valuable for common ICU diseases such as acute respiratory distress syndrome (ARDS), sepsis, pulmonary hypertension, and cardiogenic pulmonary edema. It has significant potential for diagnosing and treating these conditions in critical care medicine.

High Respiratory and Cardiac Drive Exacerbate Secondary Lung Injury in Patients With Critical Illness

The high respiratory and cardiac drive is essential to the host-organ unregulated response. When a primary disease and an unregulated secondary response are uncontrolled, the patient may present in a high respiratory and cardiac drive state. High respiratory drive can cause damage to the lungs, pulmonary circulation, and diaphragm, while high cardiac drive can lead to fluid leakage and infiltration as well as pulmonary interstitial edema. A "respiratory and cardiac dual high drive" state may be a sign of an unregulated response and can lead to secondary lung injury through the increase of transvascular pressure and pulmonary microcirculation injury. Ultrasound examination of the lung, heart, and diaphragm is important when evaluating the phenotype of high respiratory drive in critically ill patients. Ultrasound assessment can guide sedation, analgesia, and antistress treatment and reduce the risk of high respiratory and cardiac drive-induced lung injury in these patients.

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.

Effects of transcutaneous electrical diaphragmatic stimulation in critically ill elderly patients: a randomized controlled trial

BACKGROUND

Elderly patients under invasive mechanical ventilation (IMV) are more susceptible to muscle weakness. In the out-of-hospital environment, there are benefits to transcutaneous electrical diaphragmatic stimulation (TEDS), which is an easy-to-apply and low-cost technique.

OBJECTIVE

To evaluate the effect of TEDS on respiratory muscle strength, diaphragm thickness (DT), and IMV time in critically ill elderly patients.

METHODS

This was a randomized controlled trial in which patients were divided into an experimental group (EG) and a control group (CG). TEDS started 24 h after orotracheal intubation and lasted until the end of weaning. Both groups underwent the following assessments during the spontaneous breathing test after weaning from mechanical ventilation (MV): measurement of respiratory muscle strength by pressure gauge, analysis of DT by lung ultrasound, and extubation failure prevention checklist.

RESULTS

There were 23 participants in the EG and 21 in the CG. The median age was 66 (60-79) years. The mean values of the diaphragmatic thickening index in the EG and CG participants were 99.13 ± 26.75 and 66.88 ± 31.77, respectively (p = .001, Cohen's d = 1.094). The mean values of maximum inspiratory pressure in the EG and CG were 22.04 ± 3.41 and 19.34 ± 4.23 cmH2O, respectively (p = .005, Cohen's d = 0.698). The Tobin index and the integrative weaning index were similar between groups (p = .584 and p = .102, respectively). The duration of MV in the EG and CG was 6.28 ± 2.68 and 9.21 ± 2.76 days, respectively (p = .001, Cohen's d = -1.075).

CONCLUSION

Critically ill elderly patients receiving TEDS had shorter MV time, greater inspiratory muscle strength, and greater diaphragmatic contraction capacity according to their thickness fraction.

Advancing healthcare through thoracic ultrasound research in older patients

This paper reports the proceedings of a meeting convened by the Research Group on Thoracic Ultrasound in Older People of the Italian Society of Gerontology and Geriatrics, to discuss the current state-of-the-art of clinical research in the field of geriatric thoracic ultrasound and identify unmet research needs and potential areas of development. In the last decade, point-of-care thoracic ultrasound has entered clinical practice for diagnosis and management of several respiratory illnesses, such as bacterial and viral pneumonia, pleural effusion, acute heart failure, and pneumothorax, especially in the emergency-urgency setting. Very few studies, however, have been specifically focused on older patients with frailty and multi-morbidity, who frequently exhibit complex clinical pictures needing multidimensional evaluation. At the present state of knowledge, there is still uncertainty on the best requirements of ultrasound equipment, methodology of examination, and reporting needed to optimize the advantages of thoracic ultrasound implementation in the care of geriatric patients. Other issues regard differential diagnosis between bacterial and aspiration pneumonia, objective grading of interstitial syndrome severity, quantification and monitoring of pleural effusions and solid pleural lesions, significance of ultrasonographic assessment of post-COVID-19 sequelae, and prognostic value of assessment of diaphragmatic thickness and motility. Finally, application of remote ultrasound diagnostics in the community and nursing home setting is still poorly investigated by the current literature. Overall, the presence of several open questions on geriatric applications of thoracic ultrasound represents a strong call to implement clinical research in this field.

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).

Utilization of spontaneous breathing trial, objective cough test, and diaphragmatic ultrasound results to predict extubation success: COBRE-US trial

BACKGROUND

The results of clinical and weaning readiness tests and the spontaneous breathing trial (SBT) are used to predict the success of the weaning process and extubation.

METHODS

We evaluated the capacity of the cuff leak test, rate of rapid and shallow breathing, cough intensity, and diaphragmatic contraction velocity (DCV) to predict the success of the SBT and extubation in a prospective, multicenter observational study with consecutive adult patients admitted to four intensive care units. We used receiver operating characteristic (ROC) curves to assess the tests' predictive capacity and built predictive models using logistic regression.

RESULTS

We recruited 367 subjects who were receiving invasive mechanical ventilation and on whom 456 SBTs were performed, with a success rate of 76.5%. To predict the success of the SBT, we derived the following equation: (0.56 × Cough) - (0.13 × DCV) + 0.25. When the cutoff point was ≥ 0.83, the sensitivity was 91.5%, the specificity was 22.1%, and the overall accuracy was 76.2%. The area under the ROC curve (AUC-ROC) was 0.63. To predict extubation success, we derived the following equation: (5.7 × SBT) + (0.75 × Cough) - (0.25 × DCV) - 4.5. When the cutoff point was ≥ 1.25, the sensitivity was 96.8%, the specificity was 78.4%, and the overall accuracy was 91.5%. The AUC-ROC of this model was 0.91.

CONCLUSION

Objective measurement of cough and diaphragmatic contraction velocity could be used to predict SBT success. The equation for predicting successful extubation, which includes SBT, cough, and diaphragmatic contraction velocity values, showed excellent discriminative capacity.

Comparing lung aeration and respiratory effort using two different spontaneous breathing trial: T-piece vs pressure support ventilation

OBJECTIVE

To assess the changes in lung aeration and respiratory effort generated by two different spontaneous breathing trial (SBT): T-piece (T-T) vs pressure support ventilation (PSV).

DESIGN

Prospective, interventionist and randomized study.

SETTING

Intensive Care Unit (ICU) of Hospital del Mar.

PARTICIPANTS

Forty-three ventilated patients for at least 24 h and considered eligible for an SBT were included in the study between October 2017 and March 2020.

INTERVENTIONS

30-min SBT with T-piece (T-T group, 20 patients) or 8-cmH2O PSV and 5-cmH2O positive end expiratory pressure (PSV group, 23 patients).

MAIN VARIABLES OF INTEREST

Demographics, clinical data, physiological variables, lung aeration evaluated with electrical impedance tomography (EIT) and lung ultrasound (LUS), and respiratory effort using diaphragmatic ultrasonography (DU) were collected at different timepoints: basal (BSL), end of SBT (EoSBT) and one hour after extubation (OTE).

RESULTS

There were a loss of aeration measured with EIT and LUS in the different study timepoints, without statistical differences from BSL to OTE, between T-T and PSV [LUS: 3 (1, 5.5) AU vs 2 (1, 3) AU; p = 0.088; EELI: -2516.41 (-5871.88, 1090.46) AU vs -1992.4 (-3458.76, -5.07) AU; p = 0.918]. Percentage of variation between BSL and OTE, was greater when LUS was used compared to EIT (68.1% vs 4.9%, p ≤ 0.001). Diaphragmatic excursion trend to decrease coinciding with a loss of aeration during extubation.

CONCLUSION

T-T and PSV as different SBT strategies in ventilated patients do not show differences in aeration loss, nor estimated respiratory effort or tidal volume measured by EIT, LUS and DU.

Wean to Win

How to cite this article: Havaldar AA, Krishna B. Wean to Win. Indian J Crit Care Med 2023;27(10):695-696.

Pleuropulmonary and diaphragmatic ultrasound in intensive care medicine

The usefulness of ultrasound for chest exploration was described in 1968. It was not until the 1990s, when its use became widespread in Intensive Care Units as a diagnostic, monitoring and procedural guide tool. The fact that it is a non-invasive tool, accessible at the bedside, with a sensitivity and specificity close to computerized tomography (CT) and with a short learning curve, have made it a mandatory technique in the management of critically ill patients. It is essential to know that there are different air/fluid ratio generated by different pathologies that gives rise to one echographic pattern or another. The identification of these patterns together with the clinical information will allow to make an accurate diagnosis in most settings of respiratory failure. Likewise, we must not forget the importance of evaluating diaphragmatic function by ultrasound during weaning from mechanical ventilation.

Assessment of diaphragmatic function by ultrasonography in patients with systemic sclerosis and its relation to clinical parameters : A case-control study

BACKGROUND

Diaphragmatic function can be affected in many diseases and disorders. Although systemic sclerosis (SSc) is a serious connective tissue disease that affects not only the skin but also the pulmonary and musculoskeletal systems, there is insufficient information about diaphragm function.

AIMS

To compare the diaphragmatic parameters by ultrasonography (USG) in patients with SSc and healthy individuals and examine the relationship between these parameters and clinical features in patients with SSc.

METHODS

This study included 13 patients with SSc and 15 healthy individuals. Muscle thickness (in deep inspiration Tins and at the end of calm expiration Texp), changes in thickness (∆T), and thickening fraction at deep breathing were evaluated by USG. Skin thickness, pulmonary function tests, respiratory muscle strength, and the perception of dyspnea were measured as clinical features.

RESULTS

The results of Texp, Tins, and ∆T were similar in both groups (p > 0.05), albeit patients in the SSc group had less thickening fraction compared to the control group (79.9 ± 36.7 cm and 103.8 ± 20.6 cm, respectively, p < 0.05). The Tins, ∆T, and thickening fraction of the diaphragm were associated with skin thickness, pulmonary function test parameters, and respiratory muscle strength (p < 0.05). Besides, there was significant correlation between muscle thickening fraction and perception of dyspnea (p < 0.05).

CONCLUSION

These results confirm that diaphragm thickness and contractility can be affected in patients with SSc. Therefore, ultrasonographic evaluation of the diaphragm can play a complementary role to pulmonary function test and respiratory muscle strength measurement in the diagnosis and follow-up of patients with SSc.

Spinal cord perfusion pressure correlates with breathing function in patients with acute, cervical traumatic spinal cord injuries: an observational study

OBJECTIVE

This study aims to determine the relationship between spinal cord perfusion pressure (SCPP) and breathing function in patients with acute cervical traumatic spinal cord injuries.

METHODS

We included 8 participants without cervical TSCI plus 13 patients with cervical traumatic spinal cord injuries, American Spinal Injury Association Impairment Scale grades A-C. In the TSCI patients, we monitored intraspinal pressure from the injury site for up to a week and computed the SCPP as mean arterial pressure minus intraspinal pressure. Breathing function was quantified by diaphragmatic electromyography using an EDI (electrical activity of the diaphragm) nasogastric tube as well as by ultrasound of the diaphragm and the intercostal muscles performed when sitting at 20°-30°.

RESULTS

We analysed 106 ultrasound examinations (total 1370 images/videos) and 198 EDI recordings in the patients with cervical traumatic spinal cord injuries. During quiet breathing, low SCPP (< 60 mmHg) was associated with reduced EDI-peak (measure of inspiratory effort) and EDI-min (measure of the tonic activity of the diaphragm), which increased and then plateaued at SCPP 60-100 mmHg. During quiet and deep breathing, the diaphragmatic thickening fraction (force of diaphragmatic contraction) plotted versus SCPP had an inverted-U relationship, with a peak at SCPP 80-90 mmHg. Diaphragmatic excursion (up and down movement of the diaphragm) during quiet breathing did not correlate with SCPP, but diaphragmatic excursion during deep breathing plotted versus SCPP had an inverse-U relationship with a peak at SCPP 80-90 mmHg. The thickening fraction of the intercostal muscles plotted versus SCPP also had inverted-U relationship, with normal intercostal function at SCPP 80-100 mmHg, but failure of the upper and middle intercostals to contract during inspiration (i.e. abdominal breathing) at SCPP < 80 or > 100 mmHg.

CONCLUSIONS

After acute, cervical traumatic spinal cord injuries, breathing function depends on the SCPP. SCPP 80-90 mmHg correlates with optimum diaphragmatic and intercostal muscle function. Our findings raise the possibility that intervention to maintain SCPP in this range may accelerate ventilator liberation which may reduce stay in the neuro-intensive care unit.

Diagnostic Value of Pulmonary Ultrasound and Arterial Blood Gas Analysis in Acute Patients with Severe Injuries Complicated by Respiratory Failure-A Retrospective Study

Background

To investigate the early application of pulmonary ultrasonography and arterial blood gas analysis in critical patients with severe multiple injuries exacerbated by respiratory failure.

Patients and Methods

The retrospective selection was performed on 81 patients admitted to our critical care unit between January 2020 and January 2021 with severe multiple injuries rendered worse by respiratory failure. Based on the different examination procedures, the patients were categorised into three groups (n=27): group A; diagnosed with pulmonary ultrasonography, group B; diagnosed with arterial blood gas; and group C; diagnosed with both pulmonary ultrasonography and arterial blood gas analyses. Patients were subsequently divided into a survival group (n = 65) and a death group (n = 16). On an annual basis, patients' prognoses were examined in relation to the predictive value of pulmonary ultrasound.

Results

Initial diagnosis, diagnosis, and initial correct treatment times were significantly shorter in groups B and C than group A (P<0.05). In contrast, initial diagnosis time, diagnosis time, and initial correct treatment times were potentially shorter in group C than in group B (P<0.05). Compared to groups B and C, group A had a considerably lower diagnosis rate for the examination methods (P<0.05). The right diaphragm displacement and left diaphragm displacement in the survival group were potentially higher than the LUS score (P < 0.05). In contrast, the survival group's lung ultrasound score (LUS) was considerably lower than the death group's. Statistical analysis showed that the predictive values of right diaphragm displacement, left diaphragm displacement, and mean diaphragm displacement were significant compared with the LUS score. The findings of the receiver operating characteristic curve demonstrated that the right, left, and average diaphragm displacements had high predictive values.

Conclusion

In the early evaluation of patients with severe multiple injuries complicated by respiratory failure, pulmonary ultrasonography combined with arterial blood gas analysis is crucial for the rapid diagnosis and prognosis prediction of patients.

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.

Managing respiratory muscle weakness during weaning from invasive ventilation

Weaning is a critical stage of an intensive care unit (ICU) stay, in which the respiratory muscles play a major role. Weakness of the respiratory muscles, which is associated with significant morbidity in the ICU, is not limited to atrophy and subsequent dysfunction of the diaphragm; the extradiaphragmatic inspiratory and expiratory muscles also play important parts. In addition to the well-established deleterious effect of mechanical ventilation on the respiratory muscles, other risk factors such as sepsis may be involved. Weakness of the respiratory muscles can be suspected visually in a patient with paradoxical movement of the abdominal compartment. Measurement of maximal inspiratory pressure is the simplest way to assess respiratory muscle function, but it does not specifically take the diaphragm into account. A cut-off value of -30 cmH₂O could identify patients at risk for prolonged ventilatory weaning; however, ultrasound may be better for assessing respiratory muscle function in the ICU. Although diaphragm dysfunction has been associated with weaning failure, this diagnosis should not discourage clinicians from performing spontaneous breathing trials and considering extubation. Recent therapeutic developments aimed at preserving or restoring respiratory muscle function are promising.

COVID-19 Lung Ultrasound Scores and Lessons from the Pandemic: A Narrative Review

The WHO recently declared that COVID-19 no longer constitutes a public health emergency of international concern; however, lessons learned through the pandemic should not be left behind. Lung ultrasound was largely utilized as a diagnostic tool thanks to its feasibility, easy application, and the possibility to reduce the source of infection for health personnel. Lung ultrasound scores consist of grading systems used to guide diagnosis and medical decisions, owning a good prognostic value. In the emergency context of the pandemic, several lung ultrasound scores emerged either as new scores or as modifications of pre-existing ones. Our aim is to clarify the key aspects of lung ultrasound and lung ultrasound scores to standardize their clinical use in a non-pandemic context. The authors searched on PubMed for articles related to "COVID-19", "ultrasound", and "Score" until 5 May 2023; other keywords were "thoracic", "lung", "echography", and "diaphragm". A narrative summary of the results was made. Lung ultrasound scores are demonstrated to be an important tool for triage, prediction of severity, and aid in medical decisions. Ultimately, the existence of numerous scores leads to a lack of clarity, confusion, and an absence of standardization.

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.

Diaphragmatic Ultrasound Predictors of High-Flow Nasal Cannula Therapeutic Failure in Critically Ill Patients With SARS-CoV-2 Pneumonia

OBJECTIVES

High flow nasal cannula (HFNC) is frequently used in patients with acute respiratory failure, but there is limited evidence regarding predictors of therapeutic failure. The objective of this study was to assess diaphragmatic ultrasound criteria as predictors of failure to HFNC, defined as the need for orotracheal intubation or death.

METHODS

Prospective cohort study including adult patients consecutively admitted to the critical care unit, from July 24 to October 20, 2020, with respiratory failure secondary to SARS-CoV-2 pneumonia who required HFNC. After 12 hours of HFNC initiation we measured ROX index (ratio of SpO₂ /FiO₂ to respiratory rate), excursion and diaphragmatic contraction speed (diaphragmatic excursion/inspiratory time) by ultrasound, both in supine and prone position.

RESULTS

In total, 41 patients were analyzed, 25 succeeded and 16 failed HFNC therapy. At 12 hours, patients who succeeded HFNC therapy presented higher ROX index in supine position (9.8 [9.1-15.6] versus 5.4 [3.9-6.8], P < .01), and higher PaO₂ /FiO₂ ratio (186 [135-236] versus 117 [103-162] mmHg, P = .03). To predict therapeutic failure, the supine diaphragmatic contraction speed presented sensitivity of 89% and a specificity of 57%, while the ROX index presented a sensitivity of 92.8% and a specificity of 75%.

CONCLUSIONS

Diaphragmatic contraction speed by ultrasound emerges as a diagnostic complement to clinical tools to predict HFNC success. Future studies should confirm these results.

Respiratory muscle ultrasonography evaluation and its clinical application in stroke patients: A review

Background

Respiratory muscle ultrasound is a widely available, highly feasible technique that can be used to study the contribution of the individual respiratory muscles related to respiratory dysfunction. Stroke disrupts multiple functions, and the respiratory function is often significantly decreased in stroke patients.

Method

A search of the MEDLINE, Web of Science, and PubMed databases was conducted. We identified studies measuring respiratory muscles in healthy and patients by ultrasonography. Two reviewers independently extracted and documented data regarding to the criteria. Data were extracted including participant demographics, ultrasonography evaluation protocol, subject population, reference values, etc.

Result

A total of 1954 participants from 39 studies were included. Among them, there were 1,135 participants from 19 studies on diaphragm, 259 participants from 6 studies on extra-diaphragmatic inspiratory muscles, and 560 participants from 14 studies on abdominal expiratory muscles. The ultrasonic evaluation of diaphragm and abdominal expiratory muscle thickness had a relatively typically approach, while, extra-diaphragmatic inspiratory muscles were mainly used in ICU that lack of a consistent paradigm.

Conclusion

Diaphragm and expiratory muscle ultrasound has been widely used in the assessment of respiratory muscle function. On the contrary, there is not enough evidence to assess extra-diaphragmatic inspiratory muscles by ultrasound. In addition, the thickness of the diaphragm on the hemiplegic side was lower than that on the non-hemiplegic side in stroke patients. For internal oblique muscle (IO), rectus abdominis muscle (RA), transversus abdominis muscle (TrA), and external oblique muscle (EO), most studies showed that the thickness on the hemiplegic side was lower than that on the non-hemiplegic side.Clinical Trial Registration: The protocol of this review was registered in the PROSPERO database (CRD42022352901).

The Effects of Positive End Expiratory Pressure and Lung Volume on Diaphragm Thickness and Thickening

Introduction: Diaphragm dysfunction is common in patients undergoing mechanical ventilation. The application of positive end-expiratory pressure (PEEP) and the varying end-expiratory lung volume cause changes in diaphragm geometry. We aimed to assess the impact of the level of PEEP and lung inflation on diaphragm thickness, thickening fraction and displacement. Methods: An observational study in a mixed medical and surgical ICU was conducted. The patients underwent a PEEP-titration trial with the application of three random levels of PEEP: 0 cmH₂O (PEEP0), 8 cmH₂O (PEEP8) and 15 cmH₂O (PEEP15). At each step, the indices of respiratory effort were assessed, together with arterial blood and diaphragm ultrasound; end-expiratory lung volume was measured. Results: 14 patients were enrolled. The tidal volume, diaphragm displacement and thickening fraction were significantly lower with higher levels of PEEP, while both the expiratory and inspiratory thickness increased with higher PEEP levels. The inspiratory effort, as evaluated by the esophageal pressure swing, was unchanged. Both the diaphragm thickening fraction and displacement were significantly correlated with inspiratory effort in the whole dataset. For both measurements, the correlation was stronger at lower levels of PEEP. The difference in the diaphragm thickening fraction during tidal breathing between PEEP 15 and PEEP 0 was negatively related to the change in the functional residual capacity and the change in alveolar dead space. Conclusions: Different levels of PEEP significantly modified the diaphragmatic thickness and thickening fraction, showing a PEEP-induced decrease in the diaphragm contractile efficiency. When using ultrasound to assess diaphragm size and function, the potential effect of lung inflation should be taken into account.

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

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

Sugammadex Versus Neostigmine for Recovery of Respiratory Muscle Strength Measured by Ultrasonography in the Postextubation Period: A Randomized Controlled Trial

BACKGROUND

Although sugammadex is well known for its use in reducing the incidence of residual neuromuscular blockade, this has not always been translated to improved clinical measures of postoperative respiratory muscle strength. Expiratory muscles play an important role in airway clearance and inspiratory muscle capacity augmentation, yet they have not been well studied. Therefore, we tested the hypothesis on whether sugammadex could enhance expiratory muscle strength recovery more completely than neostigmine in the immediate postextubation period.

METHODS

Adult patients having microlaryngeal surgery under total intravenous anesthesia were randomized to receive sugammadex or neostigmine. The thickening fraction of internal oblique abdominal muscle (TF IO ) and diaphragm excursion, respectively, reflecting expiratory and inspiratory muscle strength, were measured via ultrasonography at 3 time points: before induction (baseline), train-of-four ratio (TOFR) recovery to 0.9, and 30 minutes after postanesthesia care unit (PACU) arrival. The primary outcome was the change in TF IO from baseline to TOFR ≥0.9. The postoperative changes of diaphragm excursion from baseline, incidences of TF IO and diaphragm excursion returning to baseline levels, and the time from TOFR 0.9 to 0.95 and 1 were also measured.

RESULTS

Among 58 patients, a significant difference in the change in TF IO from baseline to TOFR ≥0.9 between the sugammadex and neostigmine groups was observed: mean ± standard deviation, 9% ± 6% vs 16% ± 9%; difference in means: -6% (95% confidence interval [CI], -10 to -2); and adjusted P =.005 (adjusting for imbalanced variables between 2 groups). Sugammadex resulted in smaller changes in diaphragm excursion from baseline to TOFR ≥0.9 compared with neostigmine: difference in means: -0.83 cm (99.4% CI, -1.39 to -0.28 cm; Bonferroni-corrected P < .001). After 30 minutes in the postanesthesia care unit (PACU),33% of patients reversed with sugammadex versus 14% of those receiving neostigmine reached baseline TF IO levels (99.4% CI, -14 to 52; Bonferroni-corrected P > .999). The incidences of TF IO and diaphragm excursion returning to baseline were relatively low (<40%) in both groups despite TOFR reaching 1. The median time from TOFR of 0.9 to 0.95 and to 1 among patients receiving sugammadex was 7 and 10× faster than those receiving neostigmine (0.3 vs 2 minutes, Bonferroni-corrected P = .003; 0.5 vs 5.3 minutes, Bonferroni-corrected P < .001, respectively).

CONCLUSIONS

Sugammadex provides a more complete recovery of expiratory muscle strength than neostigmine at TOFR ≥0.9. Our data suggest that the respiratory muscle strength might still be impaired despite TOFR reaching 1.

Temporary phrenic nerve stimulated patients: What is the role of ultrasound examination?

BACKGROUND

Prolonged mechanical ventilation caused by ventilator-induced diaphragm dysfunction (VIDD) is a serious problem in critically ill patients. Identification of patients who will have difficulty weaning from ventilation along with attempts to reduce total time on mechanical ventilation is some of the aims of intensive care medicine.

OBSERVATIONS

This article briefly summarizes current options for temporary phrenic nerve stimulation therapy in an effort to keep the diaphragm active as direct prevention and treatment of ventilator-associated diaphragmatic dysfunction in patients on mechanical ventilation. The results of feasibility studies using different approaches are promising but so far, the clinical relevance is low. One important question is which tool would reliably identify early signs of diaphragmatic dysfunction and also be useful in guiding therapy. The authors present a brief overview of the current options considering the advantages and disadvantages of the available examination modalities. Despite the fact that current data point out some limitations of ultrasound examination, we believe that it still has a unique position in the bedside examination of critically ill patients on mechanical ventilation.

CONCLUSION

Temporary phrenic nerve stimulation, regardless of the specific approach used, has the potential to directly treat or reverse VIDD, and ultrasound examination plays an important role in the comprehensive care of critically ill patients.

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.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

New International Guidelines and Consensus on the Use of Lung Ultrasound

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

Thoracic ultrasound influences physiotherapist's clinical decision-making in respiratory management of critical care patients: a multicentre cohort study

BACKGROUND

The potential influence of thoracic ultrasound on clinical decision-making by physiotherapists has never been studied. The aim of this study was to assess the impact of thoracic ultrasound on clinical decision-making by physiotherapists for critical care patients.

METHODS

This prospective, observational multicentre study was conducted between May 2017 and November 2020 in four intensive care units in France and Australia. All hypoxemic patients consecutively admitted were enrolled. The primary outcome was the net reclassification improvement (NRI), quantifying how well the new model (physiotherapist's clinical decision-making including thoracic ultrasound) reclassifies subjects as compared with an old model (clinical assessment). Secondary outcomes were the factors associated with diagnostic concordance and physiotherapy treatment modification.

RESULTS

A total of 151 patients were included in the analysis. The NRI for the modification of physiotherapist's clinical decisions was-40% (95% CI (-56 to -22%), p=0.02). Among the cases in which treatment was changed after ultrasound, 41% of changes were major (n=38). Using a multivariate analysis, the physiotherapist's confidence in their clinical diagnosis was associated with diagnostic concordance (adjusted OR=3.28 95% CI (1.30 to 8.71); p=0.014). Clinical diagnosis involving non-parenchymal conditions and clinical signs reflecting abolished lung ventilation were associated with diagnostic discordance (adjusted OR=0.06 95% CI (0.01 to 0.26), p<0.001; adjusted OR=0.26 95% CI (0.09 to 0.69), p=0.008; respectively).

CONCLUSION

Thoracic ultrasound has a high impact on the clinical decision-making process by physiotherapists for critical care patients.

TRIAL REGISTRATION NUMBER

NCT02881814; https://clinicaltrials.gov.

Diaphragmatic Thickness and Excursion in Preterm Infants With Bronchopulmonary Dysplasia Compared With Term or Near Term Infants: A Prospective Observational Study

BACKGROUND

Diaphragmatic atrophy associated with mechanical ventilation is reported in pediatric and adult patients, but a similar association has not been described in preterm infants with bronchopulmonary dysplasia (BPD).

RESEARCH QUESTION

Does BPD impact the diaphragm thickness (DT) and diaphragm excursion (DE) in infants born before 32 weeks' gestation compared with healthy late preterm or term infants?

STUDY DESIGN AND METHODS

In this prospective observational case-control study, DT at end of expiration (DT_exp), DT at end of inspiration (DT_ins), DT fraction (DTF), and DE (DE) were assessed using bedside ultrasound. Two groups were compared: infants with BPD (patients) and healthy, postmenstrual age-matched infants (control participants). To account for variations in body size between groups, diaphragmatic measurements were expressed as a ratio of body surface area (BSA). Statistical analyses were conducted using SAS software version 9.4 (SAS Institute, Inc.).

RESULTS

We enrolled 111 infants, including 56 preterm infants with BPD (mean ± SD study age, 37.7 ± 1.7 weeks) and 55 healthy control participants (mean ± SD study age, 38.1 ± 1.5 weeks). DT_exp and DT_exp to BSA ratio were significantly lower in the BPD group compared with the healthy control group (mean ± SD, 1.3 ± 0.4 mm vs 1.5 ± 0.4 mm [P = .01] and 7.1 ± 1.4 mm/m² vs 7.8 ± 1.8 mm/m² [P = .03]). DTF and DE were significantly higher in the BPD group vs the healthy control group (mean ± SD, 61.8 ± 26.0 vs 43.3 ± 19.7 [P < .01] and 6.0 ± 1.7 mm vs 4.4 ± 1.6 mm [P < .01], respectively).

INTERPRETATION

In infants with BPD, DT_exp was significantly lower, whereas DTF and DE were significantly higher, compared with healthy, age-matched control participants. Future studies are required and should focus on describing the evolution of diaphragmatic dimensions in preterm infants with and without BPD.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT04941963; URL: www.

CLINICALTRIALS

gov.

Early passive orthostatic training prevents diaphragm atrophy and dysfunction in intensive care unit patients on mechanical ventilation: A retrospective case‒control study

BACKGROUND

Intensive care unit (ICU) patients on mechanical ventilation (MV), who are always bedridden, easily develop diaphragm atrophy and dysfunction. However, few studies have assessed diaphragmatic thickness and functional changes after early passive orthostatic training.

OBJECTIVES

This is the first study to investigate the efficacy of early passive orthostatic training in preventing diaphragm atrophy and dysfunction in ICU patients on MV.

METHODS

In this randomized retrospective case‒control study, 81 ICU patients on MV for 8 days or longer were enrolled. Forty-four patients received early passive orthostatic training initiated within 72 h of MV initiation (training group), and 37 patients did not receive training (no-training group). The protocol was performed for seven days, once a day for 30 min. The primary outcomes were diaphragmatic thickness and diaphragm contractile fraction (TFdi). The ventilatory parameters were secondary outcomes.

RESULTS

This study included 81 (45 male) ICU patients on MV [(mean ± SD) age = (60.63 ± 7.88) years]. The training group had a larger diaphragmatic thickness at end-expiration (Tdi_,ee) and a smaller magnitude of decrease in Tdi_,ee and TFdi (p = 0.001, 0.029, and <0.001, respectively) than the no-training group after 7 days of training. The mean arterial pressure, fraction of inspired oxygen, and white blood cell levels were decreased in the training group compared with the no-training group (p = 0.003, 0.001, and 0.026, respectively), but lactic acid levels decreased slightly in the training group with no significant difference (p = 0.708).

CONCLUSIONS

Early passive orthostatic training is suitable to ameliorate diaphragm atrophy and dysfunction in ICU patients on MV.

Clinical values of diaphragmatic movement in patients with chronic obstructive pulmonary disease

BACKGROUND

The limitation of activity due to dyspnea in chronic obstructive pulmonary disease (COPD) patients is affected by diaphragmatic dysfunction and reduced lung function. This study aimed to analyze the association between diaphragm function variables and forced expiratory volume in the first second (FEV1) and to estimate the clinical significance of diaphragm function in the correlation between COPD severity and lung function.

METHODS

This prospective, single-center, cross-sectional observational study enrolled 60 COPD patients in a respiratory outpatient clinic. Data for baseline characteristics and the dyspnea scale were collected. Participants underwent a pulmonary function test (PFT), a 6-minute walk test (6MWT), and diaphragm function by ultrasonography.

RESULTS

The right excursion at forced breathing showed the most significant correlation with FEV1 (r = 0.370, p = 0.004). The cutoff value was 6.7 cm of the right diaphragmatic excursion at forced breathing to identify the FEV1 above 50% group. In the group with a right diaphragmatic excursion at forced breathing < 6.7 cm, modified Medical Research Council (mMRC), St. George's Respiratory Questionnaire and the total distance of 6MWT showed no difference between groups with FEV1 under and above 50% (p > 0.05). In the group with ≥ 6.7 cm, mMRC and the total distance of 6MWT showed a significant difference between FEV1 under and above 50% (p = 0.014, 456.7 ± 69.7 m vs. 513.9 ± 60.3 m, p = 0.018, respectively).

CONCLUSION

The right diaphragmatic forced excursion was closely related to FEV1, and analysis according to the right diaphragmatic forced excursion-based cut-off value showed a significant difference between both groups. When the diaphragm function was maintained, there was a lot of difference in the 6MWT's factors according to the FEV1 value. Our data suggest that diaphragmatic function should be performed when interpreting PFT.