Lung recruitment maneuver effects on respiratory mechanics and extravascular lung water index in patients with acute respiratory distress syndrome

BACKGROUND：Animal experiments showed that recruitment maneuver （RM） and protective ventilation strategy of the lung could improve oxygenation and reduce extravascular lung water. This study was to investigate the effects of RM on respiratory mechanics and extravascular lung water index （EVLWI） in patients with acute respiratory distress syndrome （ARDS）. METHODS：Thirty patients with ARDS were randomized into a RM group and a non-RM group. In the RM group, after basic mechanical ventilation stabilized for 30 minutes, RM was performed and repeated once every 12 hours for 3 days. In the non-RM group, lung protective strategy was conducted without RM. Oxygenation index （PaO2/FiO2）, peak inspiratory pressure （PIP）, Plateau pressure （Pplat）, static pulmonary compliance （Cst） and EVLWI of patients before treatment and at 12, 24, 48, 72 hours after the treatment were measured and compared between the groups. Hemodynamic changes were observed before and after RM. One-way ANOVA, Student＇s t test and Fisher＇s exact test were used to process the data. RESULTS：The levels of PaO2/FiO2 and Cst increased after treatment in the two groups, but they were higher in the RM group than in the non-RM group （P〈0.05）. The PIP and Pplat decreased after treatment in the two groups, but they were lower in the RM group than in the non-RM group （P〈0.05）. The EVLWI in the two groups showed downward trend after treatment （P〈0.05）, and the differences were signifcant at all time points （P〈0.01）; the EVLWI in the RM group was lower than that in the non-RM group at 12, 24, 48 and 72 hours （P〈0.05 or P〈0.01）. Compared with pre-RM, hemodynamics changes during RM were significantly different （P〈0.01）; compared with pre-RM, the changes were not significantly different at 120 seconds after the end of RM （P〉0.05）. CONCLUSIONS： RM could reduce EVLWI, increase oxygenation and lung compliance. The effect of RM on hemodynamics was transient.

Recent advances in theoretical models of respiratory mechanics

As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators. To solve different clinical problems, researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system. During the past decade, benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies （e.g. biomedical imaging）, the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process, complexities of the respiratory system, gas exchange within the lungs, and the coupling interaction between lung and heart. The present paper reviews the advances in the above fields and proposes potential future projects.

Respiratory mechanics,ventilator-associated pneumonia and outcomes in intensive care unit

AIM To evaluate the predictive capability of respiratory mechanics for the development of ventilator-associated pneumonia (VAP) and mortality in the intensive care unit(ICU) of a hospital in southern Brazil. METHODS A cohort study was conducted between, involving a sample of 120 individuals. Static measurements of compliance and resistance of the respiratory system in pressure-controlled ventilation (PCV) and volumecontrolled ventilation(VCV) modes in the 1 st and 5 th days of hospitalization were performed to monitor respiratory mechanics. The severity of the patients' illness was quantified by the Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ). The diagnosis of VAP was made based on clinical, radiological and laboratory parameters.RESULTS The significant associations found for the development of VAP were APACHE Ⅱ scores above the average(P = 0.016), duration of MV (P = 0.001) and ICU length of stay above the average(P = 0.003), male gender(P = 0.004), and worsening of respiratory resistance in PCV mode(P = 0.010). Age above the average(P < 0.001), low level of oxygenation on day 1(P = 0.003) and day 5 (P = 0.004) and low lung compliance during VCV on day 1 (P = 0.032) were associated with death as the outcome.CONCLUSION The worsening of airway resistance in PCV mode indicated the possibility of early diagnosis of VAP. Low lung compliance during VCV and low oxygenation index were death-related prognostic indicators.

Model-based Analysis of Ventilation Inhomogeneity in Respiratory Mechanics

Individualized models of respiratory mechanics help to reduce potential harmful effects of mechanical ventilation by supporting the evaluation of patient-specific lung protective ventilation strategies. Assessing ventilation inhomogeneities might be an important aspect in optimizing ventilator settings. The aim of this studyis to capture and analyze ventilation inhomogeneity by a mathematical model using clinical data. The results show that the lung physiology of mechanically ventilated patients without lung condition can be described by an inhomogeneity model revealing two alveolar compartments with median time constants of 0.4 and 3.9 s. Thus, the IHM in combination with specific ventilation maneuver might be suitable to capture lung physiology for model-based optimization of ventilator settings but requires additional image-based investigations to further support the validity of the model.

Effects of Breath Training Pattern “End-Inspir atory Pause” on Respiratory Mechanics and Arterial Blood Gas of Pa tients with COPD

Objective: In order to explore the mechanism of C hinese traditional breath training, the effects of end-inspiratory pause br eathing (EIPB) on the respiratory mechanics and arterial blood gas were studied in patients with chronic obstructive pulmo nary disease (COPD).Methods: Ten patients in steady stage participating in the stud y had a breath training of regulating the respiration rhythm as to having a pause betw een the deep and slow inspiration and the slow expiration.Effect of the training was observed by visual feedback from the screen of the re spiratory inductive plethysmograph. The dynamic change of partial pressure of oxygen saturation in blood (SpO 2) was recorded with sphygmo-oximeter, the pulmonary mechanics and EIPB were determined with spirometer, and the data o f arterial blood gases in tranquilized breathing and EIPB were analysed.Results: After EIPB training, SpO 2 increased progressively, PaO 2 increased and PaCO 2 decreased, and the PaO 2 increment was greater than the PaCO 2 decrement. Furthermore, the tidal volume increased and the frequency of respira tion decreased significantly, both inspiration time and expiration time were prolonged. There was no significant change in both mean inspiration flow rate (VT/Ti) and expir ation flow rate (VT/Te). The baselines in spirogram during EIPB training had no raise. Conclusion: EIPB could decrease the ratio of the dead space and ti dal volume (VD/VT), cause increase of PaO 2 more than the decrease of PaCO 2, suggesting that this training could impro ve both the function of ventilation and gaseous exchange in the lung. EIPB training might be a breath ing training pattern for rehabilitation of patients with COPD.

Effects of nursing team communication and collaboration on treatment outcomes in intensive care unit patients with severe pneumonia

BACKGROUND Severe pneumonia is a common severe respiratory infection worldwide,and its treatment is challenging,especially for patients in the intensive care unit(ICU).AIM To explore the effect of communication and collaboration between nursing teams on the treatment outcomes of patients with severe pneumonia in ICU.METHODS We retrospectively analyzed 60 patients with severe pneumonia who were treated at the ICU of the hospital between January 1,2021 and December 31,2023.We compared and analyzed the respiratory mechanical indexes[airway resistance(Raw),mean airway pressure(mPaw),peak pressure(PIP)],blood gas analysis indexes(arterial oxygen saturation,arterial oxygen partial pressure,and oxygenation index),and serum inflammatory factor levels[C-reactive protein(CRP),procalcitonin(PCT),cortisol(COR),and high mobility group protein B1(HMGB1)]of all patients before and after treatment.RESULTS Before treatment,there was no significant difference in respiratory mechanics index and blood gas analysis index between 2 groups(P>0.05).However,after treatment,the respiratory mechanical indexes of patients in both groups were significantly improved,and the improvement of Raw,mPaw,plateau pressure,PIP and other indexes in the combined group after communication and collaboration with the nursing team was significantly better than that in the single care group(P<0.05).The serum CRP and PCT levels of patients were significantly decreased,and the difference was statistically significant compared with that of nursing group alone(P<0.05).The levels of serum COR and HMGB1 before and after treatment were also significantly decreased between the two groups.CONCLUSION The communication and collaboration of the nursing team have a significant positive impact on respiratory mechanics indicators,blood gas analysis indicators and serum inflammatory factor levels in the treatment of severe pneumonia patients in ICU.

Is COVID-19 different from other causes of acute respiratory distresssyndrome?

Coronavirus disease 2019(COVID-19)pneumonia can lead to acute hypoxemic respiratory failure.When mechanical ventilation is needed,almost all patients with COVID-19 pneumonia meet the criteria for acute respiratorydistress syndrome(ARDS).The question of the specificities of COVID-19-associated ARDS compared to othercauses of ARDS is of utmost importance,as it may justify changes in ventilatory strategies.This review aims todescribe the pathophysiology of COVID-19-associated ARDS and discusses whether specific ventilatory strategiesare required in these patients.

Comparison of the effects of deep and moderate neuromuscular block on respiratory system compliance and surgical space conditions during robot-assisted laparoscopic radical prostatectomy: a randomized clinical study

Objective:Robot-assisted radical prostatectomy(RARP)requires pneumoperitoneum(Pnp)and a steep head-down position that may disturb respiratory system compliance(Crs)during surgery.Our aim was to compare the effects of different degrees of neuromuscular block(NMB)on Crs with the same Pnp pressure during RARP.Methods:One hundred patients who underwent RARP were enrolled and randomly allocated to a deep or moderate NMB group with 50 patients in each group.Rocuronium was administered to both groups:in the moderate NMB group to maintain 1–2 responses to train-of-four(TOF)stimulation;and in the deep NMB group to maintain no response to TOF stimulation and 1–2 responses in the post-tetanic count.Pnp pressure in both groups was 10 mm Hg(1 mm Hg=133.3 Pa).Peak inspiratory pressure(Ppeak),mean pressure(Pmean),Crs,and airway resistance(Raw)were recorded after anesthesia induction and at 0,30,60,and 90 min of Pnp and post-Pnp.Surgical space conditions were evaluated after the procedure on a 4-point scale.Results:Immediately after the Pnp,Ppeak,Pmean,and Raw significantly increased,while Crs decreased and persisted during Pnp in both groups.The results did not significantly differ between the two groups at any of the time points.There was no difference in surgical space conditions between groups.Body movements occurred in 14 cases in the moderate NMB group and in one case in the deep NMB group,and all occurred during obturator lymphadenectomy.A significant difference between the two groups was observed.Conclusions:Under the same Pnp pressure in RARP,deep and moderate NMBs resulted in similar changes in Crs,and in other respiratory mechanics and surgical space conditions.However,deep NMB significantly reduced body movements during surgery.