Experimental Model of Cerebral Arterial Air Embolism in Conscious Rats.

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.

[Forensic imaging of sharp force injuries]. / Forensische Bildgebung der scharfen Gewalt.

BACKGROUND: Answering legal questions is everyday routine in forensic medicine. The reconstruction of violent crimes following attacks with sharp and/or pointed instruments is usually complex and can hardly be adequately answered using traditional forensic methods such as autopsies. For this reason, clinical and postmortem radiology has become the ideal complement to forensic medicine. METHODS: While classic X­ray is unsuitable to image soft tissue injuries, and magnetic resonance imaging is too expensive, too complex and also not available everywhere, multislice computed tomography (MSCT) has now emerged as the method of choice in forensic imaging for the assessment of the consequences of sharp force injuries. ACHIEVEMENTS: Forensic imaging, especially MSCT, offers an indispensable addition to reconstruction, particularly after stab wounds. In many cases, it is at least equal to, and in some cases superior to, the classic autopsy in the assessment of stab wounds, the reconstruction of the sequence of events or the assessment of (life-threatening) injuries. CONCLUSIONS: The forensic radiological assessment after sharp violence requires experience in both the field of radiology and forensic medicine. Provided that both disciplines work closely together, forensic radiology can be an essential tool in the care for victims of violence.

Modeling of Cerebral Ischemic Stroke in Conscious Rats via Arterial Air Embolization.

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.

Ischaemic Strokes Caused by Spontaneous Cerebral Air Embolism, A Rare Complication of Interstitial Lung Disease.

Air embolism is a rare cause of ischaemic stroke. It is known that air can enter the cerebral arterial circulation from pulmonary venous circulation through a bronchovenous fistula, or in cases of pulmonary barotrauma in deep-sea diving. We describe a case of spontaneous cerebral air embolism against a background of advanced interstitial lung disease (ILD). To our knowledge, this case demonstrates a mechanism of stroke in ILD patients that has not been previously described. LEARNING POINTS: This case demonstrates a mechanism of stroke in patients with severe interstitial lung disease (ILD) that has not been previously described, and we suggest that in cases of advanced ILD, clinicians should consider this as a possible mechanism of stroke. The management of these patients should include transferring them to hyperbaric facilities to prevent further air emboli.

Cerebral air embolism associated with cavitary lung lesion in a patient with Ehlers-Danlos syndrome.

Pneumocephalus, is a general term describing the presence of air within the intracranial structures. It most commonly occurs due to dural injury, often the sequela of head trauma or surgery. More infrequently, nontraumatic pneumocephalus can be related to infection, Valsalva, fistulization between air-containing organs and intracranial structures, or vascular air embolism. While postsurgical pneumocephalus is often benign, serious consequences of pneumocephalus exist, including tension pneumocephalus and cerebral infarction. We present a case of air embolism and cerebral infarction in a patient with Ehlers-Danlos syndrome, found to have large cavitary lesion in the left upper lobe of the lung, with associated pulmonary vascular malformation seen on bronchoscopy. To our knowledge this is the first reported case of air embolism associated with a pulmonary cavitary lesion and vascular malformation, in a patient with Ehlers-Danlos syndrome.

The risk of intraoperative venous air embolism from neurosurgical procedures performed in the lounging position: an in-depth analysis of detection, management, and outcomes of 1000 consecutive cases.

OBJECTIVE: The overall benefit of employing a sitting/semisitting position for neurosurgical procedures remains under criticism due to concerns for additional risk, especially the risk of intraoperative venous air embolism (VAE). The aim of this single-center cohort study was to evaluate the frequency and severity of VAEs and associated complications in patients undergoing neurosurgery in the lounging position. METHODS: From 2010 to 2020, 1000 patients, including 172 patients with a patent foramen ovale, underwent surgery in the lounging position for different neurosurgical pathologies. All patients were monitored intraoperatively using continuous transesophageal echocardiography (TEE). The anesthesia team documented any observed incidences of VAEs and scored their severity according to the Tuebingen classification system (TCS) for VAE (TCS-VAE). The patients' clinical condition, radiological findings, and hospital course were subsequently analyzed to assess complications in a retrospective analysis of prospectively collected data. RESULTS: In the cohort of 1000 patients, 5 underwent cervical spine surgery and 995 underwent suboccipital craniotomy. VAE was detected by TEE in 51.4% (95% CI 48.4%-54.5%) of patients, with synchronous changes in end-tidal CO2 (grade 2-5 TCS-VAE) noted in 10.2% (95% CI 8.3%-12.3%). None of the patients presented with hemodynamic instability (grade 5 TCS-VAE). Patients with high-grade VAEs were significantly older (p = 0.02) and had lower BMIs (p = 0.001) than the respective mean value of the cohort. VAE grade was not associated with any of the outcome measures such as Karnofsky Performance Scale score, duration of ventilation, length of intensive care unit stay, and length of hospital stay. Postoperative acute respiratory distress syndrome (ARDS) was diagnosed in 0.3% (95% CI 0.0%-0.7%, n = 3) of all cases, and ARDS was associated with perioperative VAE grade (p = 0.001). No patient suffered a new permanent neurological deficit due to a paradoxical VAE. CONCLUSIONS: In this large cohort, the risk of an intraoperative VAE during neurosurgery in the lounging position was assessed, and contrary to the general perception in the field, no permanent sequelae or fatal adverse events attributable to VAEs were observed. Furthermore, the overall incidence of ARDS was very low. This study clearly establishes that experienced interdisciplinary teams can safely use the lounging position for neurosurgical procedures.

Large lungs in divers: a risk for pulmonary barotrauma?

This retrospective study analysed a series of investigations on lung function in military divers and the importance of computed tomography (CT) scans concerning fitness to dive. We examined the incidence of blebs and bullae in a population of military divers with large lungs prompted by six cases of pulmonary barotrauma. All of these divers' medicals were normal apart from having large lungs (FVC > 120% predicted). A subsequent survey of the database of all divers and submariners of the Royal Netherlands Navy (RNLN) found another 72 divers/submariners with large lungs who were then evaluated by a CT scan. This resulted in the identification of three further individuals with blebs and/or bullae, who were then declared unfit to dive. In total, the incidence of these lung abnormalities in this cohort was 11.5%. We discuss the possible consequences for fitness to dive with regard to the current literature on the subject, and also consider the most recent standards of reference values for pulmonary function indices. Based on our results and additional insights from other studies, we advise using the Global Lung Initiative reference values for pulmonary function, while performing high resolution CT scans only in divers with clinical indications.

Spontaneous Air Embolism Following Contrast Injection: A Diagnostic Challenge in a Post-COVID-19 Patient.

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.

Cerebral Arterial and Venous Air Embolism Following Removal of Percutaneous Sheath Introducer.

Cerebral air embolism after removal of central venous catheter (CVC) is a rare complication but can lead to fatal outcomes. We report a rare case of both cerebral venous and arterial embolism occurring in a patient with underlying scleroderma-related interstitial lung disease (SSc-ILD) and pulmonary hypertension following removal of percutaneous introducer sheath for pulmonary artery catheterization. We discuss the mechanisms, pathophysiology, management and prevention of cerebral air embolism.

The safety and utility of the semi-sitting position for clipping of posterior circulation aneurysms.

BACKGROUND: The semi-sitting position offers advantages for surgeries in the posterior cranial fossa. However, data on its safety and effectiveness for clipping aneurysms in the posterior cerebral circulation are limited. This retrospective cohort study evaluates the safety and effectiveness of using the semi-sitting position for these surgeries. METHODS: We conducted a retrospective study of 17 patients with posterior cerebral circulation aneurysms who underwent surgical clipping in the semi-sitting position in the Department of Neurosurgery at Hannover Medical School over a 10-year period. RESULTS: The mean age at surgery was 62 years (range, 31 to 75). Fourteen patients were admitted with subarachnoid hemorrhage and 3 patients had incidental aneurysmas. Fifteen patients had PICA aneurysms, and two had aneurysms of the vertebral artery and the superior cerebellar artery, respectively. The median diameter of the aneurysms was 5 mm (range 3-17 mm). Intraoperative venous air embolism (VAE) occurred in 4 patients, without affecting the surgical or clinical course. VAE was associated with a mild decrease of EtCO2 levels in 3 patients and in 2 patients a decrease of blood pressure occurred which was managed effectively. Surgical procedures proceeded as planned in all instances. There were no complications secondary to VAE. Two patients died secondary to respiratory problems (not related to VAE), and one patient was lost to follow-up. Eleven of fourteen patients were partially or completely independent (Barthel index between 60 and 100) at a median follow-up duration of 13.5 months (range, 3-103 months). CONCLUSION: The semi-sitting position is a safe and effective technique for the surgical clipping of aneurysms in the posterior cerebral circulation. The incidence of VAE is comparable to that seen in tumor surgery. However, it is crucial for the surgical and anesthesiological team to be familiar with potential complications and to react immediately in case of an occurrence of VAE.

Patient height and American Society of Anesthesiologists class as significant risk factors for posterior fossa surgery in the semisitting position.

OBJECTIVE: To optimize surgical positioning for posterior fossa surgery (PFS) using the semisitting position (SSP) to avoid venous air embolism (VAE) and its possible life-threatening consequences, the authors evaluated their experiences with the SSP by analyzing a large cohort of PFS patients. METHODS: A retrospective analysis of the charts of 202 consecutive PFS patients (median age 54 years, IQR 41-61 years; 121 females) with various tumor or vascular conditions who underwent surgery in an SSP between 2019 and 2022 was performed. Age, sex, weight, height, BMI, American Society of Anesthesiologists (ASA) class, histology, duration of surgery, and length of hospital stay were assessed. Transesophageal echocardiography was used pre- and intraoperatively to monitor for and assess the degree of VAE. RESULTS: Altogether, VAE occurred in 30 of 202 (14.9%) patients, with clinically relevant VAE occurring in 14 of 202 (7%) patients. The grades of VAE were I, III, and IV in 16 (8%), 4 (2%), and 10 (5%) patients, respectively. Patient height (p = 0.04), ASA class (p = 0.03), and ASA class ≤ II (p = 0.02) remained the only preoperative statistically significant risk factors for intraoperative VAE, with a median height of 178 cm (IQR 172-184 cm) in patients with clinically relevant VAE compared with 170 cm (IQR 164-176 cm) in those without VAE. CONCLUSIONS: In summary, the data demonstrate that SSP can be used safely for PFS when taking special care to optimize positioning in tall and lower-grade ASA patients intraoperatively.

Cerebral Protection With Deep Hypothermic Circulatory Arrest During Total Arch Replacement Using the Arch-First Technique for Acute Aortic Dissection.

OBJECTIVES: Stroke remains a serious complication after total arch replacement (TAR). To prevent this, deep hypothermia is commonly employed during TAR. We evaluated the effectiveness of cerebral protection using deep hypothermic circulatory arrest (DHCA) during TAR with the arch-first technique, focusing particularly on patients with acute aortic dissection (AAD). METHODS: This retrospective study included 109 consecutive patients with AAD who underwent emergency TAR using the arch-first technique under DHCA, and 147 patients with non-ruptured aneurysm who underwent scheduled TAR using the same technique between October 2009 and July 2022. We reviewed these patients for major adverse events, including stroke and 30-day mortality after surgery. We also analyzed the impact of clinical variables and anatomical features on the occurrence of newly developed stroke after TAR in patients with AAD. RESULTS: A newly developed stroke after TAR occurred in 11 (10.1%) patients with AAD. These were attributed to embolism in eight patients, malperfusion in two patients (including one who had been comatose), and low output syndrome in one patient. A stroke occurred in 3 (2.0%) patients with aneurysm, all due to embolism (P = 0.005). The DHCA time was 37 ± 7 minutes for patients with AAD and 36 ± 6 minutes for patients with aneurysm (P = 0.122). The 30-day mortality rate was 10 (9.2%) for patients with AAD and 2 (1.4%) for patients with aneurysm (P = 0.003). In our multivariable analysis, arch vessel dissection with a patent false lumen (double-barreled dissection) was the only significant predictor of newly developed stroke after TAR for AAD (odds ratio, 33.02; P < 0.001). CONCLUSIONS: Patients with aneurysm undergoing TAR using the arch-first technique under DHCA experienced significantly better outcomes, in terms of newly developed stroke and 30-day mortality, than those with AAD. Cerebral protection with DHCA during TAR using the arch-first technique continues to be a viable option. Newly developed stroke in patients undergoing TAR for AAD appears to be associated with air emboli deriving from the residual dissection with a patent false lumen in the repaired arch vessels.

Paradoxical air embolism in patients undergoing hysteroscopic surgery for cesarean scar pregnancy: A case report and review of the literatures.

Cesarean scar pregnancy cases who undergo hysteroscopic suction aspiration could be at higher risk of air emboli due to dilated, low-resistant, high-velocity blood vessels.

Intraoperative Challenge: Managing Venous Air Embolism During Sitting Craniotomy.

Venous air embolism (VAE) represents a rare yet potentially life-threatening complication encountered during neurosurgical procedures, particularly craniotomy. Here, we present a case of a 30-year-old male undergoing excision of a cerebellar abscess who developed VAE midway through the procedure. Immediate recognition and intervention were paramount in managing the embolism effectively, ensuring a favorable surgical outcome. Vigilant monitoring, prompt cessation of the procedure, and implementation of preventive measures such as oxygen therapy and venous air aspiration were pivotal in mitigating the embolism's effects. This study underscores the critical importance of intraoperative vigilance, preparedness, and multidisciplinary teamwork in addressing rare but potentially catastrophic complications during neurosurgical interventions.

Cerebral air embolism: neurologic manifestations, prognosis, and outcome.

Background: Cerebral air embolism (CAE) is an uncommon medical emergency with a potentially fatal course. We have retrospectively analyzed a set of patients treated with CAE at our comprehensive stroke center and a hyperbaric medicine center. An overview of the pathophysiology, causes, diagnosis, and treatment of CAE is provided. Results: We retrospectively identified 11 patients with cerebral venous and arterial air emboli that highlight the diversity in etiologies, manifestations, and disease courses encountered clinically. Acute-onset stroke syndrome and a progressive impairment of consciousness were the two most common presentations in four patients each (36%). Two patients (18%) suffered from an acute-onset coma, and one (9%) was asymptomatic. Four patients (36%) were treated with hyperbaric oxygen therapy (HBTO), high-flow oxygen therapy without HBOT was started in two patients (18%), two patients (18%) were in critical care at the time of diagnosis and three (27%) received no additional treatment. CAE was fatal in five cases (46%), caused severe disability in two (18%), mild disability in three (27%), and a single patient had no lasting deficit (9%). Conclusion: Cerebral air embolism is a dangerous condition that necessitates high clinical vigilance. Due to its diverse presentation, the diagnosis can be missed or delayed in critically ill patients and result in long-lasting or fatal neurological complications. Preventative measures and a proper diagnostic and treatment approach reduce CAE's incidence and impact.

Veno-arterial extracorporeal membrane oxygenation for the treatment of obstructive shock caused by venous air embolism: A case report.

BACKGROUND: 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. CASE SUMMARY: 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. CONCLUSION: ECMO may be an important treatment for patients with VAE in critical condition.

Air embolism complicating endoscopic retrograde cholangiopancreatography.

Aim: Venous air embolism is a rare but potentially life threatening complication of endoscopic retrograde cholangiopancreatography. Diagnosis is difficult because of the lack of specific signs or symptoms. Case: A 62-year-old man underwent endoscopic retrograde cholangiopancreatography for choledocholithiasis. A cardiovascular collapse occurred during the procedure. The echocardiography showed air within the right ventricle. Aspiration of air from the right ventricle was done and saved the patient's life. Conclusion: We highlight through this case that increased awareness is essential for prompt recognition of the air embolism to allow life-saving therapy.

Endoscopic treatment is the first-line treatment for biliary stones. It may be associated with various complications. We report the case of a 62-year-old patient who underwent endoscopic treatment for biliary stone. During the procedure, he experienced disturbed cardiac function due to the passage of air bubbles into the cardiac cavities. The bubbles were aspirated with a good outcome.

Stroke Secondary to Air Embolism Following Laparoscopic Nissen Fundoplication.

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.

Effect of a helium and oxygen mixture on physiological parameters of rats with cerebral arterial air embolism.

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.