Lung damage created by high tidal volume ventilation in rats with monocrotaline-induced pulmonary hypertension

Ventilator-induced lung injury in rat models: are they all equal in the race?

Risk of ventilator-induced lung injury (VILI) is an inevitable and precarious accompaniment of ventilator treatment in critically ill patients worldwide. It can both instigate and aggravate acute respiratory distress syndrome (ARDS) where the only prevention or treatment so far has been empirical approach of what is considered to be lung protective ventilator settings in an attempt to shield the lung tissues against the mechanical stress that unavoidably follows ventilator treatment. The weakened state of the patients limits clinical drug research and pushes for drug discovery in animal models. Mice and rats are often the choice of small animal model, representing about 95% of all laboratory animal studies, as their physiology can mimic that which is found in humans. Mice have been a more popular choice for ventilator studies but due to technical issues, there is some advantage gained in using rats as they are substantially larger. Inducing VILI and ARDS in these models can prove challenging and often the acute nature of the injury used to produce similar tissue damage as in humans does not necessarily fully reflect clinical reality. The aim of this review was to analyse and summarize methods of recent publications in the field, describing what approaches have been utilized to simulate these conditions, possibly identifying a common track enabling comparison of results between studies. However, the study shows a high variety of methods employed by researchers causing comparisons of results difficult and perhaps implying that a more standardized approach should be used.

Optimizing perioperative lung protection strategies for reducing postoperative respiratory complications in pediatric patients: a narrative review

Background and Objective

Despite significant advancements in the safe delivery of anesthesia and improvements in surgical techniques, postoperative respiratory complications (PRCs) remain a serious concern. PRCs can lead to increased length of hospital stay, worsened patient outcomes, and higher hospital and postoperative costs. Perioperative lung injury and PRCs are more common in children than in adults owing to children's unique physiology and anatomical characteristics. Studies have shown that lung-protective ventilation (LPV) strategies can improve lung function and minimize the risk of PRCs in adults. However, individualized LPV in children remains underexplored. This narrative review provides an overview of the various perioperative pulmonary protection strategies and their effect on pediatric PRCs.

Methods

We searched PubMed for articles published from 2000 to 2024, setting our inclusion criteria to include studies that involved pediatric patients, addressed LPV strategies, and reported data on PRCs. Non-English language studies, case reports, editorials, conference abstracts, and non-full text published literatures were excluded. We utilized the following keyword strategy: (((lung protective ventilation) OR (PEEP)) OR (recruitment maneuver)) OR (low tidal volume) AND (2000:2024[pdat])) AND (pediatric) filters. In total, 1,106 articles were retrieved, with only 23 being deemed relevant to the review. Data extraction and analysis were conducted by two independent researchers to ensure accuracy and consistency. We conducted descriptive statistical analysis for quantitative data and thematic analysis for qualitative data.

Key Content and Findings

The key content are an overview of risk factors for PRCs in children including the patients themselves, anesthesia, and surgery, as well as the effectiveness of LPV strategies in pediatric surgery, including low tidal volume (TV), positive end-expiratory pressure (PEEP), ultrasound-guided pulmonary recruitment maneuver (RM), low fraction of inspired oxygen (FiO2), pressure-controlled ventilation (PCV), as well as fluids, pain, and high-flow nasal cannula (HFNC). We found that age, mechanical ventilation with general anesthesia, and thoracic surgery increased the risk of PRCs in children. The application of LPV strategies in pediatric surgery had positive effect, including low TV combined with titrated PEEP, age- and physiologically appropriate FiO2, ultrasound-guided RM, target directed fluid infusion, adequate analgesia, and the use of HFNC in special circumstances. However, we also found that the application of LPV has certain potential risks and therefore needs to be implemented according to the patient's actual age and physical condition.

Conclusions

Perioperative LPV strategies show potential benefits in reducing lung injury and PRCs in pediatric patients. These strategies, including low TV, appropriate individualized PEEP, lung RM, and avoidance of high FiO2, appear to be effective methods for protecting lung function in pediatric patients. Additionally, perioperative fluid management and effective pain control are crucial for lung protection. The emerging use of HFNC therapy shows promise, but further research is needed to fully understand its benefits.

Urokinase-loaded cyclic RGD-decorated liposome targeted therapy for in-situ thrombus of pulmonary arteriole of pulmonary hypertension

Backgroud: In-situ thrombosis is a significant pathophysiological basis for the development of pulmonary hypertension (PH). However, thrombolytic therapy for in-situ thrombus in PH was often hampered by the apparent side effects and the low bioavailability of common thrombolytic medications. Nanoscale cyclic RGD (cRGD)-decorated liposomes have received much attention thanks to their thrombus-targeting and biodegradability properties. As a result, we synthesized urokinase-loaded cRGD-decorated liposome (UK-cRGD-Liposome) for therapy of in-situ thrombosis as an exploration of pulmonary hypertensive novel therapeutic approaches. Purpose: To evaluate the utilize of UK-cRGD-Liposome for targeted thrombolysis of in-situ thrombus in PH and to explore the potential mechanisms of in-situ thrombus involved in the development of PH. Methods: UK-cRGD-Liposome nanoscale drug delivery system was prepared using combined methods of thin-film hydration and sonication. Induced PH via subcutaneous injection of monocrotaline (MCT). Fibrin staining (modified MSB method) was applied to detect the number of vessels within-situ thrombi in PH. Echocardiography, hematoxylin-eosin (H & E) staining, and Masson's trichrome staining were used to analyze right ventricular (RV) function, pulmonary vascular remodeling, as well as RV remodeling. Results: The number of vessels with in-situ thrombi revealed that UK-cRGD-Liposome could actively target urokinase to in-situ thrombi and release its payload in a controlled manner in the in vivo environment, thereby enhancing the thrombolytic effect of urokinase. Pulmonary artery hemodynamics and echocardiography indicated a dramatical decrease in pulmonary artery pressure and a significant improvement in RV function post targeted thrombolytic therapy. Moreover, pulmonary vascular remodeling and RV remodeling were significantly restricted post targeted thrombolytic therapy. Conclusion: UK-cRGD-Liposome can restrict the progression of PH and improve RV function by targeting the dissolution of pulmonary hypertensive in-situ thrombi, which may provide promising therapeutic approaches for PH.