Ultrasound variations of diaphragm activity between prone position versus supine position in ventilated patients: a cross-sectional comparative study

Effect of five different body positions on lung function in stroke patients with tracheotomy

BACKGROUND

In stroke patients with tracheotomy, reduced lung function heightens pulmonary infection risk. Body position can affect lung function; however, its impact in stroke patients with tracheostomy remains unclear.

OBJECTIVE

To investigate the influence of five body positions on pulmonary function in stroke patients with tracheotomy.

METHODS

Pulmonary function was assessed in five body positions (supine, supine 30°, supine 60°, sitting, and prone) in 47 stroke patients who underwent tracheotomy. Diaphragmatic excursion during quiet breathing (DEQ), diaphragmatic thickening fraction during quiet breathing (DTFQ), and diaphragmatic excursion during coughing (DEC) were measured using ultrasound. Peak cough flow (PCF) was measured using an electronic peak flow meter.

RESULTS

Different positions had a significant impact on DEQ, DEC, and PCF in stroke patients with tracheotomy, although not on DTFQ. DEQ showed no significant differences between supine 60°, sitting, and prone positions. Both DEC and PCF reached their maximum values in the sitting position. In the sub-group analysis, DEQ in females did not show significant differences across different positions. Both males and females exhibited significantly higher PCF in the sitting compared to supine position. The lung function of obese patients was significantly better in the sitting than in the supine and supine 30° position. Regardless of the patient's level of consciousness and whether the brainstem was injured, lung function in the sitting position was significantly higher than in the supine position.

CONCLUSIONS

Body posture influences lung function in stroke patients with tracheotomy. Patients should adopt a sitting position to enhance pulmonary function.

Exploring ultrasonographic diaphragmatic function in perioperative anesthesia setting: A comprehensive narrative review

The ultrasound study of diaphragm function represents a valid method that has been extensively studied in recent decades in various fields, especially in intensive care, emergency, and pulmonology settings. Diaphragmatic function is pivotal in these contexts due to its crucial role in respiratory mechanics, ventilation support strategies, and overall patient respiratory outcomes. Dysfunction or weakness of the diaphragm can lead to respiratory failure, ventilatory insufficiency, and prolonged mechanical ventilation, making its assessment essential for patient management and prognosis in critical care and emergency medicine. While several studies have focused on diaphragmatic functionality in the context of intensive care, there has been limited attention within the field of anesthesia. The ultrasound aids in assessing diaphragmatic dysfunction (DD) by measuring muscle mass and contractility and their potential variations over time. Recent advancements in ultrasound imaging allow clinicians to evaluate diaphragm function and monitor it during mechanical ventilation more easily. In the context of anesthesia, early studies have shed light on the patho-physiological mechanisms of diaphragm function during general anesthesia. In contrast, more recent research has centered on evaluating diaphragmatic functionality at various phases of general anesthesia and by comparing diverse types of procedures or anatomical position during surgery. The objectives of this current review are to highlight the use of diaphragm ultrasound for the evaluation of diaphragmatic function during perioperative anesthesia and surgery. Specifically, we aim to examine the effects of anesthetic agents, surgical techniques, and anatomical positioning on diaphragmatic function. We explore how ultrasound aids in assessing DD by measuring muscle mass and contractility, as well as their potential variations over time. Additionally, we will discuss recent advancements in ultrasound imaging that allow clinicians to evaluate diaphragm function and monitor it during mechanical ventilation more easily.

Diaphragm Assessment by Multimodal Ultrasound Imaging in Healthy Subjects

Background

In recent years, diaphragm ultrasound (DUS) has been used to identify diaphragm dysfunction in the intensive care unit (ICU). However, there are few studies on DUS parameters to evaluate function, normal ranges, and influencing factors in population. The aim of this study is to provide a methodological reference for clinical evaluation of diaphragm function by measuring different DUS parameters in a healthy population.

Methods

A descriptive study was conducted 212 (105 males, 107 females) subjects with normal spirometry underwent ultrasound imaging in this study. The diaphragm contraction and motion related parameters and shear wave velocity (SWV) were measured in the supine position. The effects of gender, age, body mass index (BMI) and lifestyle on diaphragm ultrasound parameters were analyzed.

Results

The diaphragm thickness at end-expiration (DT-exp) was 0.14 ±0.05 cm, the diaphragm thickness at end- inspiration (DT-insp) was 0.29±0.10 cm, with thickening fraction (TF) was 1.11±0.54. The diaphragm excursion (DE) was 1.68±0.37cm and diaphragm velocity was 1.45±0.41 cm/s during calm breathing. During deep breathing, the DE was 5.06±1.40cm and diaphragm velocity was 3.20±1.18 cm/s. The Diaphragm shear modulus-longitudinal view were Mean16.72±4.07kPa, Max25.04±5.58kPa, Min11.06±3.88kPa, SD2.56±0.98. The results of diaphragmatic measurement showed that the DT of males was significantly greater than that of females (P< 0.05), but there was no significant difference in TF. The DT-insp (r=0.155, P= 0.024) and the DT-exp (r=0.252, P=0.000) were positively correlated with age, and the DE during calm breathing was negatively correlated with age (r=-0.218, P= 0.001) and BMI (r=-00.280, P= 0.000). The DE (R=0.371, P=0.000) and velocity (R=0.368, P=0.000) during deep breathing were correlated with lifestyle.

Conclusion

Our study provides normal reference values of the diaphragm and evaluates the influence of gender, age, body mass index and lifestyle on diaphragmatic morphology.

Prone Positioning Decreases Inhomogeneity and Improves Dorsal Compliance in Invasively Ventilated Spontaneously Breathing COVID-19 Patients—A Study Using Electrical Impedance Tomography

Background: We studied prone positioning effects on lung aeration in spontaneously breathing invasively ventilated patients with coronavirus disease 2019 (COVID-19). Methods: changes in lung aeration were studied prospectively by electrical impedance tomography (EIT) from before to after placing the patient prone, and back to supine. Mixed effect models with a random intercept and only fixed effects were used to evaluate changes in lung aeration. Results: fifteen spontaneously breathing invasively ventilated patients were enrolled, and remained prone for a median of 19 [17 to 21] hours. At 16 h the global inhomogeneity index was lower. At 2 h, there were neither changes in dorsal nor in ventral compliance; after 16 h, only dorsal compliance (βFe +18.9 [95% Confidence interval (CI): 9.1 to 28.8]) and dorsal end-expiratory lung impedance (EELI) were increased (βFe, +252 [95% CI: 13 to 496]); at 2 and 16 h, dorsal silent spaces was unchanged (βFe, –4.6 [95% CI: –12.3 to +3.2]). The observed changes induced by prone positioning disappeared after turning patients back to supine. Conclusions: in this cohort of spontaneously breathing invasively ventilated COVID-19 patients, prone positioning decreased inhomogeneity, increased lung volumes, and improved dorsal compliance.

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

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

Ultrasound assessment of the diaphragm during the first days of mechanical ventilation compared to spontaneous respiration: a comparative study

INTRODUCTION

In critically ill patients, the diaphragm is subject to several aggressions mainly those induced by mechanical ventilation (MV). Currently, diaphragmatic ultrasound has become the most useful bedside for the clinician to evaluate diaphragm contractility.

AIM

  To examine the effects of MV on the diaphragm contractility during the first days of ventilation.

METHODS

Two groups of subjects were studied: a study group (n=30) of adults receiving MV versus a control group (n=30) of volunteers on spontaneous ventilation (SV). Using an ultrasound device, we compared the diaphragmatic thickening fraction (DTF). Secondly, we analysed the relationship between DTF and weaning.

RESULTS

comparatively to SV group, patients of MV group have a higher end expiratory diameter (EED) (2.09 ± 0.6 vs. 1.76 ± 0.32 mm, p=0.01) and a lower DTF (39.9 ± 12.5%  vs.  49.0 ± 20.5%, p=0.043). Fourteen among the 30 ventilated patients successfully weaned. No significant correlation was shown between DTF and weaning duration (Rho= - 0.464, p=0.09). A DTF value > 33% was near to be significantly associated with weaning success (OR=2; 95% CI= [1.07-3.7], p=0.05) with a sensitivity at 85.7%.

CONCLUSIONS

diaphragmatic contractility was altered from the first days of MV. A DTF value >32,7% was associated to the weaning success and that may be useful to predict successful weaning with sensitivity at 85.7%.