Acute lung injury and post-cardiac arrest syndrome: a narrative review

Background

Post-cardiac arrest syndrome (PCAS) presents a multifaceted challenge in clinical practice, characterized by severe neurological injury and high mortality rates despite advancements in management strategies. One of the important critical aspects of PCAS is post-arrest lung injury (PALI), which significantly contributes to poor outcomes. PALI arises from a complex interplay of pathophysiological mechanisms, including trauma from chest compressions, pulmonary ischemia–reperfusion (IR) injury, aspiration, and systemic inflammation. Despite its clinical significance, the pathophysiology of PALI remains incompletely understood, necessitating further investigation to optimize therapeutic approaches.

Methods

This review comprehensively examines the existing literature to elucidate the epidemiology, pathophysiology, and therapeutic strategies for PALI. A comprehensive literature search was conducted to identify preclinical and clinical studies investigating PALI. Data from these studies were synthesized to provide a comprehensive overview of PALI and its management.

Results

Epidemiological studies have highlighted the substantial prevalence of PALI in post-cardiac arrest patients, with up to 50% of survivors experiencing acute lung injury. Diagnostic imaging modalities, including chest X-rays, computed tomography, and lung ultrasound, play a crucial role in identifying PALI and assessing its severity. Pathophysiologically, PALI encompasses a spectrum of factors, including chest compression-related trauma, pulmonary IR injury, aspiration, and systemic inflammation, which collectively contribute to lung dysfunction and poor outcomes. Therapeutically, lung-protective ventilation strategies, such as low tidal volume ventilation and optimization of positive end-expiratory pressure, have emerged as cornerstone approaches in the management of PALI. Additionally, therapeutic hypothermia and emerging therapies targeting mitochondrial dysfunction hold promise in mitigating PALI-related morbidity and mortality.

Conclusion

PALI represents a significant clinical challenge in post-cardiac arrest care, necessitating prompt diagnosis and targeted interventions to improve outcomes. Mitochondrial-related therapies are among the novel therapeutic strategies for PALI. Further clinical research is warranted to optimize PALI management and enhance post-cardiac arrest care paradigms.

Key Points

1. Epidemiology of PALI: Up to 50% of post-cardiac arrest survivors experience acute lung injury, with diagnostic tools like CT scans and lung ultrasounds critical for identifying and assessing the extent of damage.
2. Pathophysiology: PALI arises from a combination of chest compression trauma, aspiration during CPR, pulmonary IR injury, and systemic inflammation, all of which contribute to alveolar-capillary membrane disruption.
3. Role of Ventilation Strategies: Lung-protective ventilation, with low tidal volumes and optimized PEEP, is essential to mitigate ventilator-induced lung injury (VILI) in PCAS patients, improving outcomes and reducing mortality.
4. Therapeutic Hypothermia: Cooling strategies have demonstrated mixed results, with some evidence suggesting benefits in reducing inflammation and lung injury in animal models, though clinical efficacy remains uncertain.
5. Mitochondrial Dysfunction: Damaged mitochondria release DAMPs, exacerbating inflammation and oxidative stress, which are critical in PALI. Mitochondria-targeted therapies, such as antioxidants and transplantation, hold promise for future treatment.
6. ARDS in PCAS: Acute respiratory distress syndrome (ARDS) frequently complicates PCAS, linked to factors like hyperoxia, aspiration, and systemic inflammation. ARDS management protocols are vital in post-cardiac arrest care.
7. Emerging Imaging Tools: Advanced imaging modalities, including quantitative CT and lung ultrasound, offer superior diagnostic and prognostic capabilities, enabling timely and precise assessment of PALI.
8. Mechanical Chest Compression Risks: Mechanical compressions during CPR increase pulmonary edema risk, contributing to transient hypoxia and impaired compliance, necessitating careful evaluation of resuscitation methods.
9. Potential of ECMO: Extracorporeal membrane oxygenation (ECMO) has shown potential in minimizing ventilatory-induced damage while supporting oxygenation and hemodynamics in severe PALI cases.
10. Future Directions: Research priorities include refining therapeutic hypothermia protocols, developing bedside tools for mitochondrial function assessment, and investigating innovative pharmacological and mechanical therapies for PALI.

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