Quantification of diaphragmatic dynamic dysfunction in septic patients by bedside ultrasound
Our prospective observational study has provided evidence to systematically assess sepsis-induced diaphragm dysfunction (SIDD) by bedside ultrasound. Diaphragmatic mobility parameters were used to quantify during deep breathing and quiet breathing among sepsis group 1 (2 ≤ SOFA ≤ 5), sepsis group 2 (SOFA > 5), and control group. The main findings were as follows: (1) Contractile dysfunction occurred before diaphragmatic atrophy in septic patients. (2) The severity of diaphragm dysfunction can be quantitatively analyzed by ultrasound parameters in septic patients. Dynamic parameters including TF, EQC/Ecomics, compared to deep breathing and quiet breathing, reflected earlier dysfunction. (3) Maximum contractile velocity decreased significantly in sepsis group 1, accurately reflecting damage to intrinsic contraction efficiency. (4) AUDMC (either per breath or per minute), the integral of diaphragmatic excursion during contraction over time, decreased in septic patients in our study, reflecting reduced diaphragmatic respiratory effort for effectively overcome resistance loads.
In fact, diaphragmatic dysfunction was both a marker of disease severity and a predictor of poor outcomes in critical care patients.seven. Previous studies of diaphragmatic ultrasound have mainly focused on predicting the probability of weaning from mechanical ventilation in the intensive care unit, the relative parameters of which included thickness, TF, and excursion.12,13,21. Of these, TF is much more accurate than excursion22. In our study, abnormal TF and EQC/Ecomics obtained better early assessment of diaphragm dysfunction in septic patients. Because they reflected the relationship between contractile function in calm breathing and maximal contractile reserve.
The function of the diaphragm depends not only on the strength of the contractile force but also on the speed of contraction of the diaphragm. The variation in chest pressure generated by peak inspiratory effort is primarily determined by the intrinsic contractile properties of the diaphragm and is not affected by lung compliance or structural changes in the chest wall, which may better reflect efficiency. diaphragmatic contraction with precision.23.24. In our study, the maximum contractile velocity, reflecting the fastest rate of diaphragm contraction per unit time, decreased significantly in the septic groups compared to that of the control group, and decreased more significantly in the septic group 2 than in septic group 1.
In fact, the same excursion could represent different respiratory efforts because inspiratory time and respiratory rate are not taken into account.25. The area under the diaphragmatic motion curve (AUDMC) in the inspiratory phase is the integral of the diaphragmatic excursion during contraction over time (either per breath or per minute). During the inspiratory phase, the shortening of the fibers of the diaphragm produced a downward piston-like action, which the radius of the diaphragmatic dome-shaped structure changes from time to time.7,10,26. Our study found a positive correlation between TF and AUDMC. Because TF has been proven to reflect respiratory efforts by research by Goligher et al12, AUDMC may also reflect diaphragmatic effort. Whether AUDMC covering the inspiratory process can accurately represent respiratory effort needs to be confirmed by further studies in the future. Additionally, AUDMC per minute was calculated to better predict pump operation and diaphragm endurance. In our study, AUDMC per breath in the sepsis group 1 was lower than in the control group, but AUDMC per minute was compensated by the increase in respiratory rate. However, AUDMC per minute in sepsis group 2 was not compensated, indicating progressive diaphragm failure.
Sepsis is a series of clinical syndromes caused by infection, resulting in multi-organ dysfunction, including diaphragmatic dysfunction. Several cellular and molecular mechanisms have been implicated in SIDD, including oxidative stress and activation of multiple proteolytic pathways2. Sepsis-induced diaphragmatic dysfunction includes the two aspects of decreased diaphragm contractility and diaphragm atrophy2. We found that contractile dysfunction was earlier than diaphragmatic atrophy in the septic patients in our study, which was confirmed by basic and clinical studies.16.27. With the worsening of the severity of the infection, we found a further decrease in the diaphragmatic contractile function by ultrasound, including the parameters of TF, EQC/EDB, deep breathing speed and AUDMC. Therefore, the diaphragm ultrasound technique can be used to assess both diaphragmatic contraction function and structural change in septic patients.
Although there is no international standard for diaphragmatic ultrasound techniques compared to cardiac ultrasound, it has been increasingly studied in recent years as it is non-invasive and has no potential radioactive damage like computed tomography and x-rays.5,7,21. To exclude the influence of clinically relevant confounders, analysis of covariance was performed for each parameter separately, adjusted for age, sex, body mass index, MAP, hypertension and diabetes in our study. Among them, the dynamic evaluation parameters including TF and EQC/Ecomics compared quiet breathing with maximum inspiration in the patients themselves, which reduced errors caused by different individuals and different instruments.
All septic patients were grouped according to SOFA scores, as this is not only a diagnostic criterion, but also more important evidence to help clinicians identify the severity of infection early and initiate treatment accordingly. timely.28. By comparing the more severe sepsis in group 2 with that of sepsis in group 1, we found that certain diaphragmatic ultrasound parameters can be used to assess diaphragmatic damage earlier. This study therefore provides a basis for routine clinical assessment of diaphragmatic function in the future. To exclude additional influence on diaphragmatic function, all patients underwent diaphragmatic ultrasound prior to mechanical ventilation. Of course, these parameters should also be studied in other septic patients and clinical diseases.