Gas embolism is a rare but life-threatening process characterized by the presence of gas bubbles in the venous or arterial systems. These bubbles, if sufficiently large or numerous, can block the delivery of oxygen to critical organs, in particular the brain, and subsequently they can trigger a cascade of adverse biochemical reactions with severe medical outcomes. Despite its critical nature, gas embolism remains poorly understood, necessitating extensive investigation, particularly regarding its manifestations in the human body and its modulation by various biological conditions. However, given its elusive nature, as well as potential lethality, gas embolism is extremely difficult to study in vivo, and nearly impossible to be the subject of clinical trials. To this end, we developed a microfluidic device designed to study in vitro the impact of blood properties and vascular geometries on the formation and evolution of gas bubbles. The system features a biomimetic vascular channel surrounded by two pressure chambers, which induce the genesis of bubbles under varying circumstances. The bubble parameters were correlated with different input parameters, i.e., channel widths, wall thicknesses, viscosities of the artificial blood, and pressure levels. Smaller channel widths and higher equivalent hematocrit concentrations in synthetic blood solutions increased the nucleation density and bubble generation frequencies. Small channel widths were also more prone to bubble formation, with implications for the vulnerability of vascular walls, leading to increased risks of damage or compromise to the integrity of the blood vessels. Larger channel widths, along with higher equivalent hematocrit concentrations, translated into larger bubble volumes and decreased bubble velocities, leading to an increased risk of bubble immobilization within the blood vessels. This biomimetic approach provides insights into the impact of patient history and biological factors on the incidence and progression of gas embolism. Medical conditions, such as anemia, along with anatomical features related to age and sex-such as smaller blood vessels in women and children or larger vascular widths in adult men-affect the susceptibility to the initiation and progression of gas embolism, explored here in vitro through the development of a controlled, physiological-like environment. The analysis of the videos that recorded gas embolism events in vitro for systems where pressure is applied laterally on the microvasculature with thin walls, i.e., 50 μm or less, suggests that the mechanism of gas transfer for the pressure area to the blood is based on percolation, rather than diffusion. These findings highlight the importance of personalized approaches in the management and prevention of gas embolism.

The question of whether scuba diving is safe for patients with a history of venous thromboembolism (VTE) remains unanswered. Cases of VTE have been reported after decompression accidents but not following properly conducted dives. However, the risk of VTE and bleeding on anticoagulant therapy during diving has yet to be defined. Medical diving societies make different recommendations regarding the risk of scuba diving in patients with a history of VTE and/or hereditary thrombophilia and regarding the bleeding risk under anticoagulation associated with dives. There is no epidemiologic or pathophysiologic evidence described in the literature to support a direct association between VTE and diving. Therefore, VTE cannot be considered as a definite contraindication for scuba diving. Further studies are needed to conclusively establish the risk of VTE associated with diving and to guide the development of medical guidelines by diving societies.

Ophthalmic surgical procedures are widely acknowledged for their safety and efficacy. Undoubtedly, advances in ophthalmic surgery, along with the improvement of anaesthetic techniques, have contributed to the reduction in the occurrence of these events. However, although uncommon, systemic severe and life-threatening adverse events can still occur and it is imperative for an ophthalmologic surgeon to have a comprehensive understanding of them to act in terms of proactive prevention, prompt recognition, and optimal treatment, thus maximizing patients' outcomes. Among life-threatening complication following ophthalmic surgery, cardiovascular events represent the most common ones, including a range of different clinical entities: the oculocardiac reflex, potentially leading to haemodynamic instability and asystole; iatrogenic vascular air embolism, in form of venous air embolism or "pefluorocarbon syndrome", which can lead to obstruction of the pulmonary circulation, respiratory distress and cardiovascular collapse; postoperative venous thromboembolism, in the context of which the management of perioperative antiplatelet and anticoagulant therapy has a crucial role. Furthermore, among infectious complications, that are more commonly limited to the ocular tissues, necrotizing fasciitis represents a potentially lethal infection. This review aims to provide an up-to-date, evidence-based overview of potential life-threatening complications associated with ophthalmic surgery, exploring pathogenesis, risk factors, signs, symptoms, and, briefly, management strategies.

Systemic air embolism, though rare, poses a significant risk as a complication of CT-guided lung lesion ablation. This condition often arises from the formation of a transient bronchovascular fistula, which can occur when a needle punctures the lung or accidentally breaches a pulmonary vein. In this report, we present a case involving acute cerebral infarction resulting from retrograde venous embolism linked to a fistula between the pleural cavity and pulmonary artery after pulmonary ablation. The patient demonstrated clear signs and symptoms but ultimately recovered fully and was discharged without lasting effects. This case underscores the critical need for ongoing vigilance and proactive measures to prevent air embolism during such medical procedures.

Venous air embolism is a rare but potentially fatal complication arising from traumatic injuries or medical procedures, characterized by the intravascular introduction of air leading to the formation of gas emboli within the pulmonary vasculature and cardiac chambers. Here, we present the case of a 34-year-old female with a history of substance abuse who sustained a head injury during an altercation. Despite initial resistance to medical assistance due to intoxication, she eventually received treatment for a significant head wound. A postmortem examination revealed a triangular wound penetrating through the scalp layers, accompanied by extensive bruises indicative of trauma. Notably, air embolism was discovered in the venous and cardiac systems, primarily attributed to injury of the temporal vein near the head wound. This complication was most likely exacerbated by an underlying coagulation disorder stemming from mixed nodular cirrhosis of the liver. The failure of damaged veins to thrombose and inadequate occlusion of venous lumens might have further facilitated air ingress into the venous system, culminating in a fatal outcome. This case underscores the importance of recognizing and promptly managing head injuries, especially in patients with a history of substance abuse and coexisting medical conditions such as liver disease. Improved awareness and education regarding the risks of substance abuse and the significance of seeking timely medical intervention for traumatic injuries are crucial in preventing similar tragic consequences in the future.

In this work, an optimal air supply mode was selected to create a model of cerebral arterial air embolism (CAAE) on conscious male Sprague-Dawley rats (n=49). The efficacy of the selected model (administration of 100 μl/kg of air at a rate of 10 μl/min with an infusion pump) was determined by changes in serum biochemical parameters (cholesterol, alkaline phosphatase, inorganic phosphates, AST, and triglycerides), impaired motor functions in the Rotarod test, and visual assessment of the ischemic foci (staining of frontal sections with 1% triphenyltetrazolium chloride solution) at different terms after AAE. The model of AAE created by us confirmed impairment of coordination and motor function in conscious animals and reproduced the lethal consequences of this condition. The obtained results can serve as the basis for drug testing and the development of new approaches to the treatment of ischemic stroke.

The etiological factor of cerebral ischemia in the vast majority of cases is vascular embolism. In the present study we investigated embolism caused by atmospheric air bubbles injected into the internal carotid artery of conscious rats. Immediately after embolism modeling, behavioral abnormalities were observed in the animals, and after 24 h, foci of brain damage were detected. The death of animals was observed within 5 days after embolism. The proposed experimental model of cerebral ischemia in conscious rats is more relevant and better corresponds to real conditions than the model on narcotized animals and allows to perform physiological tests immediately after modeling.

A 72-year-old male with a complex medical history, including chronic obstructive pulmonary disease (COPD), hypertension, atrial fibrillation, and a recent COVID-19 infection, presented to the emergency department with shortness of breath and chest pain. Physical examination revealed stable vital signs but notable bilateral decreased air entry and diffuse wheezing. A computed tomography angiogram (CTA) of the chest confirmed a small to moderate volume of air embolism within the main pulmonary artery and right ventricle, with no evidence of pulmonary embolism. The air embolism was suspected to have been introduced during a contrast injection for the CT scan, as no other iatrogenic factors, recent invasive procedures, or history of lung trauma were present. Initial management included repositioning the patient to a supine position and administering 100% oxygen, which was critical in stabilizing his condition. Despite the ongoing symptoms of shortness of breath, the patient's condition improved with supportive care focused on managing COPD exacerbation. Spontaneous air embolism without decompression sickness or prior instrumentation is exceptionally rare, particularly in a post-COVID-19 patient, making this case notable. It highlights the critical need for prompt recognition, thorough evaluation, and appropriate management of air embolism in complex medical scenarios to prevent life-threatening complications. This case also underscores the importance of considering iatrogenic causes, such as contrast injection, in the differential diagnosis, especially following recent imaging studies.

Venous air embolism (VAE) is a potentially lethal condition, with a reported incidence rate of about 0.13%, and the true incidence may be higher since many VAE are asymptomatic. The current treatments for VAE include Durant's maneuver, aspiration and removal of air through venous catheters, and hyperbaric oxygen therapy. For critically ill patients, use of cardiotonic drugs and chest compressions remain useful strategies. The wider availability of extracorporeal membrane oxygenation (ECMO) has brought a new option for VAE patients.

A 53-year-old female patient with VAE presented to the emergency clinic due to abdominal pain with fever for 1 d and unconsciousness for 2 h. One day ago, the patient suffered from abdominal pain, fever, and diarrhea. She suddenly became unconscious after going to the toilet during the intravenous infusion of ciprofloxacin 2 h ago, accompanied by nausea and vomiting, during which a small amount of gastric contents were discharged. She was immediately sent to a local hospital, where cranial and chest computed tomography showed bilateral pneumonia as well as accumulated air visible in the right ventricle and pulmonary artery. The condition deteriorated despite endotracheal intubation, rehydration, and other treatments, and the patient was then transferred to our hospital. Veno-arterial ECMO was applied in our hospital, and the patient's condition gradually improved. The patient was successfully weaned from ECMO and extubated after two days.

ECMO may be an important treatment for patients with VAE in critical condition.

Decompression sickness (DCS) is a systemic syndrome that can occur after an environmental pressure reduction. Previously, we showed that the plasmatic tetrameric form of transthyretin (TTR) nearly disappeared in rats suffering DCS but not in asymptomatic ones. In this pilot study, we assessed whether the resistance to DCS could be associated with polymorphism of the gene of TTR. For this study, Sanger sequencing was performed on purified PCR products from the liver of 14-week-old male and female standard and DCS-resistant rats (n = 5 per group). Hepatic TTR mRNA expression was assessed by RT-qPCR in 18-19 week-old male and female standard and resistant rats (n = 6 per group). There is a synonymous single nucleotide polymorphism (SNP) on the third base of codon 46 (c.138 C > T). The thymine allele was present in 90% and 100% of males and females standard, respectively. However, this allele is present in only 30% of DCS-resistant males and females (p = 0.0002301). In the liver, there is a significant effect of the resistance to DCS (p = 0.043) and sex (p = 0.047) on TTR expression. Levels of TTR mRNA were lower in DCS-resistant animals. To conclude, DCS resistance might be associated with a SNP and a lower expression of TTR.

Introduction: Cerebral arterial air embolism (CAE) is a serious and potentially dangerous condition that can interrupt the blood supply to the brain and cause stroke. One of the promising gas mixtures for emergency treatment of air embolism is an oxygen-helium mixture. Methods: We modeled CAE in awake rats by injecting air into the common carotid artery. Immediately after CAE, animals were either untreated or underwent hyperbaria, oxygen inhalation, heated air inhalation, or helium-oxygen mixture inhalation. Body temperature, locomotor activity, respiratory and cardiovascular parameters were monitored in the animals before CAE modeling, and 3 and 24 h after CAE modeling. Results: After 3 hours of CAE modeling in awake rats, depression of the nervous, cardiovascular and respiratory systems, as well as decreased body temperature were observed. 24 h after CAE modeling multifocal cerebral ischemia was observed. Normobaric helium-oxygen mixture inhalation, on par with hyperbaric treatment, restored body temperature, locomotor activity, respiratory volume, respiratory rate, and blood pressure 3 hours after CAE, and prevented the formation of ischemic brain damage lesions 24 h after CAE. Discussion: Thus, inhalation of a heated oxygen-helium gas mixture (O2 30% and He 70%) immediately after CAE improves the physiological condition of the animals and prevents the foci of ischemic brain damage formation.

Air embolization is usually an iatrogenic complication that can occur in both veins and arteries. Intravenous air embolization is mainly associated with large central vein catheters and mechanical ventilation. A 59-year-old woman was sent to our hospital with spontaneous cerebral hemorrhage and treated conservatively with a left forearm peripheral venous catheter infusion drug. After 48 hours, the patient's oxygen saturation decreased to 92 % with snoring breathing. Computer tomography of the head and chest revealed scattered gas in the right subclavian, the right edge of the sternum, the superior vena cava, and the leading edge of the heart shadow.

She was sent to the intensive care unit for high-flow oxygen inhalation and left-side reclining instantly. As the patient was at an acute stage of cerebral hemorrhage and did not take the Trendelenburg position.

The computed tomography (CT) scan after 24 hours shows that the air embolism subsides.

Air embolism can occur in any clinical scenario, suggesting that medical staff should enhance the ability to identify and deal with air embolism. For similar cases in clinical practice, air embolism can be considered.

An air embolism is characterized by the entry of gas bubbles into the circulatory system, which can lead to the possible occlusion of blood vessels, posing a potentially life-threatening risk. While commonly associated with lung trauma or decompression sickness, it can also result from medical procedures such as central venous catheter insertion or, in our case, gas insufflation for laparoscopic surgery. We present the case of a 65-year-old female who suffered from a stroke secondary to an air embolism after undergoing a laparoscopic Nissen fundoplication in which carbon dioxide insufflation of the abdominal cavity was utilized. We also will discuss the elusive etiology of this complication as well as diagnosis, treatment, and proposed preventative measures.  A 65-year-old female with gastroesophageal reflux disease and a hiatal hernia elected to undergo a laparoscopic Nissen fundoplication for hernia repair. After a successful surgery, the patient was found with significant neurological deficits, including left-sided hemiplegia, numbness in the left hand, hemianopsia, dysarthria, and a National Institutes of Health Stroke Scale score of 20. CT head imaging revealed several low-density foci in the right frontal lobe, while CT neck and chest imaging revealed subcutaneous emphysema and pneumomediastinum. Subsequent labs were significant for an elevated lactate at 7.6 mmol/L. MRI of the brain depicted evidence of an acute infarct in the right frontal lobe with diffusion-weighted imaging (DWI) sequences. The imaging results were correlated with the patient's clinical presentation to establish the diagnosis of a nondominant hemisphere stroke, localized to an anterior branch of the right middle cerebral artery (MCA). After intubation and supportive treatment for three days, the patient was extubated and able to follow commands but had left facial weakness and diminished strength in the left upper and lower extremities. At the two-month follow-up visit, the patient no longer had any focal neurological deficits. Air emboli, though very rare, can occur as a complication in laparoscopic surgeries that utilize CO2 for body cavity insufflation. Patients may be asymptomatic with small, self-limiting emboli, while others may exhibit pulmonary symptoms, cardiac arrest, or focal neurologic changes, depending on the emoji's size and location. Given the wide range of patient presentations, the elevated mortality of laparoscopic procedures complicated by air emboli, and the rare occurrence of focal neurological symptoms as depicted in this case, rapid diagnosis and close postoperative observation and treatment are vital for both short-term and long-term patient outcomes.

Pediatric liver transplantation is an important modality for treating biliary atresia. The overall survival rate of pediatric liver transplantation has significantly improved. The incidence of perioperative cardiac events was evaluated, and risk factors were also investigated in adult patients undergoing liver transplantation in previous studies. To the best of our knowledge, this is the first case of a cardiac event during a pediatric living-donor liver transplantation.

Our report describes the management of cardiac events during a liver transplantation in a 7-month-old girl. The ST segment began to increase to 3.0 mm immediately after reperfusion, with peak ST-segment elevation reaching 13.2 mm after 45 min. The procedure ended uneventfully after continuous symptomatic and etiological treatment. It was considered to be the occurrence of an acute air embolism complication during the procedure based on the electrocardiograph and biomarkers. An echocardiogram during follow-up showed a patent foramen ovale with a left-to-right shunt tract width of 2.7 mm.

Pediatric liver transplantation has become a state-of-the-art treatment for children with end-stage liver disease and can improve the quality of life to some extent. These children may be complicated with congenital heart disease, which increases the risk of surgery. Application of echocardiogram, close monitoring, and appropriate management may reduce the incidence of perioperative cardiac events.