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

Exploring diaphragmatic response to high-flow nasal cannula in patients with COVID-19 pneumonia using ultrasound: a proof of concept study

BACKGROUND

Recent studies have highlighted the recognition of diaphragmatic dysfunction as a significant factor contributing to respiratory disturbances in severely ill COVID-19 patients. In the field of noninvasive respiratory support, high-flow nasal cannula (HFNC) has shown effectiveness in relieving diaphragm dysfunction. This study aims to investigate the diaphragmatic response to HFNC in patients with COVID-19 pneumonia by utilizing ultrasound.

METHODS

This retrospective study was conducted in a medical-surgical intensive care unit (ICU) at a tertiary care center in Buenos Aires, Argentina (Sanatorio de Los Arcos) over a 16-month period (January 2021-June 2022). The study included patients admitted to the ICU with a diagnosis of COVID-19 pneumonia who were deemed suitable candidates for HFNC therapy by the attending physician. Diaphragm ultrasound was conducted, measuring diaphragmatic excursion (DE) both before and during the utilization of HFNC for these patients.

RESULTS

A total of 10 patients were included in the study. A statistically significant decrease in respiratory rate was observed with the use of HFNC (p = 0.02), accompanied by a significant increase in DE (p = 0.04).

CONCLUSION

HFNC leads to a reduction in respiratory rate and an increase in DE as observed by ultrasound in patients with COVID-19 pneumonia, indicating promising enhancements in respiratory mechanics. However, further research is required to validate these findings.

Intercostal Muscle Function During Noninvasive Ventilation and Acute Hypercapnic Respiratory Failure

BACKGROUND

Noninvasive ventilation (NIV) is a widely used and well-established treatment modality for respiratory failure. In patients with increased respiratory work of breathing, accessory muscles are commonly activated along with the diaphragm. Whereas diaphragm ultrasound has been utilized to assess outcomes of mechanical ventilation, the data on intercostal muscle ultrasound remain limited. We aimed to investigate the association between intercostal muscle thickening fraction (TF) and NIV failure in critical care patients with hypercapnic respiratory failure.

METHODS

Critical care subjects receiving NIV for hypercapnic respiratory failure were enrolled in the study. The intercostal muscle TF was measured on admission day (day 0) and the following day (day 1). NIV failure was defined as the need for invasive mechanical ventilation or death during NIV therapy.

RESULTS

A total of 158 subjects were enrolled, and 30 experienced NIV failure. Age, sex, and body mass index (BMI) were similar in the NIV success and failure groups. Acute Physiology And Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scores were higher in the NIV failure group. In terms of causes of respiratory failure, the COPD exacerbation rate was higher in the NIV success group. TF was higher in the NIV failure group on both day 0 and day 1. The increased TF on the ICU admission day, with a cutoff value of 12%, was associated with NIV failure after adjusting for age, sex, BMI, APACHE II, and SOFA. Persistence of a higher TF value on both day 0 and day 1 was also associated with NIV failure risk.

CONCLUSIONS

There was a positive relation between intercostal muscle TF measured by ultrasound and NIV failure, even after adjusting for APACHE II and SOFA scores.

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.

The role of ultrasound in predicting non-invasive ventilation outcomes: a systematic review

Purpose

To systematically review and compare ultrasonographic methods and their utility in predicting non-invasive ventilation (NIV) outcomes.

Methods

A systematic review was performed using the PubMed, Medline, Embase, and Cochrane databases from January 2015 to March 2023. The search terms included the following: ultrasound, diaphragm, lung, prediction, non-invasive, ventilation, and outcomes. The inclusion criteria were prospective cohort studies on adult patients requiring non-invasive ventilation in the emergency department or inpatient setting.

Results

Fifteen studies were analyzed, which comprised of 1,307 patients (n = 942 for lung ultrasound score studies; n = 365 patients for diaphragm dysfunction studies). Lung ultrasound scores (LUS) greater than 18 were associated with NIV failure with a sensitivity 62-90.5% and specificity 60-91.9%. Similarly, a diaphragm thickening fraction (DTF) of less than 20% was also associated with NIV failure with a sensitivity 80-84.6% and specificity 76.3-91.5%.

Conclusion

Predicting NIV failure can be difficult by routine initial clinical impression and diagnostic work up. This systematic review emphasizes the importance of using lung and diaphragm ultrasound, in particular the lung ultrasound score and diaphragm thickening fraction respectively, to accurately predict NIV failure, including the need for ICU-level of care, requiring invasive mechanical ventilation, and resulting in higher rates of mortality.

Ultrasonographic evaluation of the diaphragm in critically ill patients to predict invasive mechanical ventilation

BACKGROUND

Diaphragm dysfunction is common in critically ill patients and associated with poorer outcomes. The function of the diaphragm can be evaluated at the bedside by measuring diaphragmatic excursion using ultrasonography. In this study, we investigated the ability of right-sided diaphragmatic excursion (RDE) to predict the need for invasive mechanical ventilation (IMV).

METHODS

Critically ill patients aged 18 years and older who presented to our emergency department between May 20, 2021 and May 19, 2022 and underwent measurement of RDE within 10 min of arrival were enrolled in this prospective study. The ability of RDE to predict the need for IMV was assessed by multivariable logistic regression and analysis of the area under the receiver-operating characteristic curve (AUROC).

RESULTS

A total of 314 patients were enrolled in the study; 113 (35.9%) of these patients required IMV. An increase of RDE value per each 0.1 cm was identified to be an independent predictor of IMV (adjusted odds ratio 0.08, 95% confidence interval [CI] 0.04-0.17, p < 0.001; AUROC 0.850, 95% CI 0.807-0.894). The RDE cutoff value was 1.2 cm (sensitivity 82.3%, 95% CI 74.0-88.8; specificity 78.1%, 95% CI 71.7-83.6). Time on a ventilator was significantly longer when the RDE was ≤ 1.2 cm (13 days [interquartile range 5, 27] versus 5 days [interquartile range 3, 8], p = 0.006).

CONCLUSIONS

In this study, RDE had a good ability to predict the need for IMV in critically ill patients. The optimal RDE cutoff value was 1.2 cm. Its benefit in patient management requires further investigation.

Diaphragm ultrasound evaluation during weaning from mechanical ventilation in COVID-19 patients: a pragmatic, cross-section, multicenter study

Background

Diaphragmatic dysfunction is a major factor responsible for weaning failure in patients that underwent prolonged invasive mechanical ventilation for acute severe respiratory failure from COVID-19. This study hypothesizes that ultrasound measured diaphragmatic thickening fraction (DTF) could provide corroborating information for weaning COVID-19 patients from mechanical ventilation.

Methods

This was an observational, pragmatic, cross-section, multicenter study in 6 Italian intensive care units. DTF was assessed in COVID-19 patients undergoing weaning from mechanical ventilation from 1st March 2020 to 30th June 2021. Primary aim was to evaluate whether DTF is a predictive factor for weaning failure.

Results

Fifty-seven patients were enrolled, 25 patients failed spontaneous breathing trial (44%). Median length of invasive ventilation was 14 days (IQR 7–22). Median DTF within 24 h since the start of weaning was 28% (IQR 22–39%), RASS score (− 2 vs − 2; p = 0.031); Kelly-Matthay score (2 vs 1; p = 0.002); inspiratory oxygen fraction (0.45 vs 0.40; p = 0.033). PaO2/FiO2 ratio was lower (176 vs 241; p = 0.032) and length of intensive care stay was longer (27 vs 16.5 days; p = 0.025) in patients who failed weaning. The generalized linear regression model did not select any variables that could predict weaning failure. DTF was correlated with pH (RR 1.56 × 1027; p = 0.002); Kelly-Matthay score (RR 353; p < 0.001); RASS (RR 2.11; p = 0.003); PaO2/FiO2 ratio (RR 1.03; p = 0.05); SAPS2 (RR 0.71; p = 0.005); hospital and ICU length of stay (RR 1.22 and 0.79, respectively; p < 0.001 and p = 0.004).

Conclusions

DTF in COVID-19 patients was not predictive of weaning failure from mechanical ventilation, and larger studies are needed to evaluate it in clinical practice further.

Registered: ClinicalTrial.gov (NCT05019313, 24 August 2021).

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.