Venous Air Embolism Research Articles

An open-source framework for synthetic post-dive Doppler ultrasound audio generation.

Doppler ultrasound (DU) measurements are used to detect and evaluate venous gas emboli (VGE) formed after decompression. Automated methodologies for assessing VGE presence using signal processing have been developed on varying real-world datasets of limited size and without ground truth values preventing objective evaluation. We develop and report a method to generate synthetic post-dive data using DU signals collected in both precordium and subclavian vein with varying degrees of bubbling matching field-standard grading metrics. This method is adaptable, modifiable, and reproducible, allowing for researchers to tune the produced dataset for their desired purpose. We provide the baseline Doppler recordings and code required to generate synthetic data for researchers to reproduce our work and improve upon it. We also provide a set of pre-made synthetic post-dive DU data spanning six scenarios representing the Spencer and Kisman-Masurel (KM) grading scales as well as precordial and subclavian DU recordings. By providing a method for synthetic post-dive DU data generation, we aim to improve and accelerate the development of signal processing techniques for VGE analysis in Doppler ultrasound.

Acute and Subacute Neurovascular Impact of Cryptogenic Air Emboli (P12-5.020)

<h3>Objective:</h3> To describe a unique case of severe, delayed ischemia secondary to air embolism. <h3>Background:</h3> Accidental air embolism is a rare cause of ischemic stroke that is becoming increasingly well-described in the literature. However, the mechanism and severity of this type of injury can vary, with significant ischemia typically emerging early in the course of care. To our knowledge, delayed ischemia in this setting has rarely been described. <h3>Design/Methods:</h3> We describe a hospitalized patient who developed cryptogenic air emboli resulting in acute neurologic changes that appeared to improve with emergent care. However, follow up imaging revealed delayed ischemia not identified on initial radiography. <h3>Results:</h3> A stroke code was called for an unresponsive, hospitalized 75-year-old man. On evaluation, he was found to be obtunded with forced left gaze deviation concerning for possible non-convulsive status epilepticus (NCSE). He was treated acutely for seizure and subsequent stat CT head revealed air within the right greater than left hemispheric cortical veins with loss of sulcation, concerning for developing ischemia. On review of his hospitalization, prior TTE showed no PFO. Retrograde movement of air into the cortical veins was the hypothesized etiology,¹ but the source of the air in this case remains cryptogenic. MRI obtained 5.75 hours after the patient’s last known well showed subtle diffusion restriction without definitive cortical infarction and follow up CT head approximately 13 hours afterward showed near complete resolution of the air emboli. However, MRI 4 days later demonstrated diffusion restriction and cerebral edema throughout multiple vascular territories, consistent with venous infarction. <h3>Conclusions:</h3> This case highlights that venous air emboli can cause delayed ischemia that may not be appreciated on initial dedicated brain imaging. As such, affected patients may require intensive neurocritical care irrespective of initial radiographic findings. <b>Disclosure:</b> Dr. Gummerson has nothing to disclose. Dr. Parasram has nothing to disclose. Dr. Peng has nothing to disclose. Dr. Picard has nothing to disclose. Dr. Kahn has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Biohaven. Dr. Kahn has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Chronius. Dr. Kahn has stock in Coaptech. Dr. Kahn has stock in Quantum Labs. Dr. Kahn has stock in FVC Health. Dr. Kahn has stock in TEO Science . Dr. Kahn has received intellectual property interests from a discovery or technology relating to health care. Dr. Angelus has nothing to disclose. Dr. Bhatt has nothing to disclose. Dr. De Havenon has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Integra. Dr. De Havenon has stock in Certus. The institution of Dr. De Havenon has received research support from NIH/NINDS. The institution of Dr. De Havenon has received research support from Regeneron Pharmaceuticals. The institution of Dr. De Havenon has received research support from AMAG Pharmaceuticals. The institution of Dr. De Havenon has received research support from AMGEN. Dr. De Havenon has received publishing royalties from a publication relating to health care. Dr. Jasne has nothing to disclose. Dr. Magid-Bernstein has nothing to disclose.

Reduction of venous air embolism in coronary computed tomography angiography using a modified method of saline test injection

ObjectivesThis paper analyzed the feasibility of reducing venous air emboli introduced during tube connection in computed tomography angiography (CTA) through a modified method of saline test injection.MethodsA total of 386 cases of patients undergoing coronary CTA examination were randomly arranged into a control group (199 patients underwent conventional saline injection before the CTA examination) and a case group (187 patients underwent modified saline injection before the CTA examination). The two groups were compared for the location (Fisher’s exact test), number (χ2 test), and diameter (Mann-Whitney rank sum test) of the air emboli along the inflow direction of contrast agent within the scan.ResultsThe occurrence rate was 10.55% in the control group and 3.74% in the case group respectively, with a statistically different significance (P = 0.010). In the case group, there were 7 cases of small-grade venous air emboli. In the control group, there were 15 cases of small-grade venous air emboli and 6 cases of moderate-grade venous air emboli. No cases of large-grade venous air emboli were found in both groups.ConclusionsThe use of this modified method of saline test injection before CTA examination is able to effectively decrease the occurrence of venous air emboli introduced during tube connection, which has some certain practical significance.

Cerebral venous air embolism after central line removal

Cerebral venous air embolism after central line removal

Massive Venous Air Embolism in a Case of Hysteroscopy: A Rare Grave Complication in a Comparatively Simple Procedure

Hysteroscopic surgery has gained popularity but lethal complication like gas or venous air embolism can occur. It can be recognized by a decrease in oxygen saturation and sudden drop in end-tidal carbon dioxide and may sometimes lead to severe organ failure and death depending on the amount of air embolism. We report the case of a 55-year-old female with no comorbidities posted for evaluation of postmenopausal bleeding by diagnostic hysteroscopy. The procedure was performed under spinal anesthesia using normal saline as distending media. Midway between the procedures, the patient developed severe bradycardia and desaturation. Hence, with the diagnosis of massive pulmonary embolism, the patient was resuscitated but could not be revived. The fatal outcome from a comparatively simple procedure is not uncommon. Complications are to be kept in mind and possible precautionary measures are to be taken at all times. As the eye cannot see what the mind does not know.

Decompression strain in parachute jumpmasters during simulated high-altitude missions: a special reference to preoxygenation strategies

PurposeMilitary parachute operations are often executed at high altitude, from an unpressurized aircraft compartment. Parachute jumpmasters (JM) are thus regularly exposed to 29,500 ft for 60 min. The aim was to investigate the decompression strain during a simulated JM mission at high altitude and to compare two strategies of preoxygenation, conducted either at sea-level or below 10,000 ft, during ascent to mission altitude.MethodsTen JM completed, on separate occasions, a 45-min preoxygenation either at sea-level (normobaric: N) or 8200ft (hypobaric: H), followed by exposure to 28,000 ft for 60 min, whilst laying supine and breathing 100% oxygen. At min 45 of the exposure to 28,000 ft, the JM performed 10 weighted squats. Decompression strain was determined from ultrasound assessment of venous gas emboli (VGE) during supine rest (5-min intervals), after three unloaded knee-bends (15-min intervals) and immediately following the weighted squats. The VGE were scored using a six-graded scale (0–5).ResultsIn condition H, two JM experienced decompression sickness (DCS), whereas no DCS incidents were reported in condition N. The prevalence of VGE was higher in the H than the N condition, at rest [median(range), 3(0–4) vs 0(0–3); p = 0.017], after unloaded knee-bends [3(0–4) vs 0(0–3); p = 0.014] and after the 10 weighted squats [3(0–4) vs 0(0–3); p = 0.014]. VGE were detected earlier in the H (28 ± 20 min, p = 0.018) than the N condition (50 ± 19 min).ConclusionsA preoxygenation/altitude procedure commonly used by JM, with a 60-min exposure to 28,000 ft after pre-oxygenation for 45 min at 8200 ft is associated with high risk of DCS. The decompression strain can be reduced by preoxygenating at sea level.

How to position the patient? A meta-analysis of positioning in vestibular schwannoma surgery via the retrosigmoid approach.

Patient positioning is a matter of ongoing debate in the surgical treatment of vestibular schwannoma (VS). Main endpoints of this discussion are preservation of facial nerve functioning, extent of resection, and complications. In this meta-analysis, we aim to investigate the impact of patient positioning on VS surgery via the retrosigmoid approach. We searched for eligible comparative trials on PubMed, Cochrane library, and Web of Science. Positioning groups were compared regarding facial nerve outcome, extent of resection, postoperative hydrocephalus, postoperative CSF leaks, perioperative venous air embolism, and perioperative mortality. Two groups of positions were defined, and the following positions were allocated to those groups: (1) Semi-sitting and Sitting-position; (2) Lateral position, supine position with extensive head rotation, lateral oblique (=Fukushima/Three-quarter prone), and park-bench position. From 374 full-text screenings, 7 studies met the criteria and were included in our meta-analysis comprising 1640 patients. Our results demonstrate a significantly better long-term (≥6 months) outcome of the facial nerve after VS surgery in the semi-sitting positioning (OR: 1.49, 95%CI: 1.03-2.15, p = 0.03). Positioning did not influence the extent of resection, rate of postoperative CSF leaks, and the presence of a postoperative hydrocephalus. Overall incidence of venous air embolisms was significantly associated with VS surgery in sitting positioning (OR: 6.77, 95% CI: 3.66-12.54, p < 0.00001). Perioperative mortality was equal among both positioning groups. Semi-sitting positioning seems to be associated with an improved facial nerve outcome after VS surgery via the retrosigmoid approach. Venous air embolisms are significantly more often observed among VS patients who underwent surgery in the sitting position, but the perioperative mortality is equal in both positioning groups. Both positioning groups are a safe procedure. Multicentric prospective randomized trials are needed to evaluate the risk-benefit ratio of each positioning in VS surgery via the retrosigmoid approach.

Catastrophic and Critical Intraoperative Events during Pediatric Craniofacial Surgery.

The data reviewed included the operative procedures of two senior craniofacial surgeons over an 18-year period at a tertiary care pediatric craniofacial center. Catastrophic or critical intraoperative events were defined as events requiring the activation of an emergency code during surgery. The operative details and acute outcomes were reviewed and analyzed. This study reviewed 7214 procedures performed between January 2002 and January 2019. There were 2072 (29%) cases classified as major craniofacial procedures (transcranial, mixed trans-and-extracranial, or major extracranial facial osteotomies), and code events occurred in 14 cases (0.67%; one in 148 patients): venous air embolism (n = 4), cardiac complications (n = 3), major hemorrhage (n = 3), trigeminocardiac reflex (n = 2), acute intracranial hypertension (n = 1), and acute airway obstruction (n = 1). Two cases (14%) experienced a critical event that was anesthesia-related. Cardiac arrest requiring compressions and/or defibrillation was necessary for eight patients. There were no mortalities. Surgery was curtailed in seven cases and successfully completed in seven patients. Catastrophic life-threatening events during pediatric craniofacial surgery are, fortunately, rare. In our institution, experienced teams in the management of catastrophic and critical intraoperative events during major pediatric craniofacial procedures resulted in no mortalities.

Commentary: Comparison of newer hand-held ultrasound devices for post-dive venous gas emboli quantification to standard echocardiography.

We read with interest the study by Karimpour et al. (2022) comparing two new portable devices to standard echography on the task of Venous Gas Embolism (VGE) detection in scuba divers. In operating conditions of open water dives, the authors compared portable 2D echograph Butterfly iQ and Doppler ultrasound device O'Dive to a 2D echograph Vivid Q currently used for VGE detection in research. There are however several important aspects of the study that need to be considered. To evaluate monitoring difficulty with each device in operating conditions the reader would need (i) 39 the total number of dives that authors attempted to monitor, (ii) the number of dives successfully 40 monitored at least once with at least one device, (iii) the number of VGE scores obtained with each 41 device, (iv) the number of dives with a full set of measurements for each device. Moreover, it would 42 be pertinent to report if for some divers the monitoring was complicated or impossible due to some 43 physiological characteristics. Unfortunately, the only information about monitored dives and divers 44 provided was the number of subjects enrolled in the study. 45The authors excluded from analysis VGE scores from devices when a paired measurement from other

Treatment of hepatic venous system hemorrhage and carbon dioxide gas embolization during laparoscopic hepatectomy via hepatic vein approach.

With the improvement of laparoscopic surgery, the feasibility and safety of laparoscopic hepatectomy have been affirmed, but intraoperative hepatic venous system hemorrhage and carbon dioxide gas embolism are the difficulties in laparoscopic hepatectomy. The incidence of preoperative hemorrhage and carbon dioxide gas embolism could be reduced through preoperative imaging evaluation, reasonable liver blood flow blocking method, appropriate liver-breaking device, controlled low-center venous pressure technology, and fine-precision precision operation. In the case of blood vessel rupture bleeding in the liver vein system, after controlling and reducing bleeding, confirm the type and severity of vascular damage in the liver and venous system, take appropriate measures to stop the bleeding quickly and effectively, and, if necessary, transfer the abdominal treatment in time. In addition, to strengthen the understanding, prevention and emergency treatment of severe CO2 gas embolism in laparoscopic hepatectomy is also the key to the success of surgery. This study aims to investigate the methods to deal with hepatic venous system hemorrhage and carbon dioxide gas embolization based on author's institutional experience and relevant literature. We retrospectively analyzed the data of 60 patients who received laparoscopic anatomical hepatectomy of hepatic vein approach for HCC. For patients with intraoperative complications, corresponding treatments were given to cope with different complications. After the operation, combined with clinical experience and literature, we summarized and discussed the good treatment methods in the face of such situations so that minimize the harm to patients as much as possible.

A fully automated algorithm for heart rate detection in post-dive precordial Doppler ultrasound

Background: Doppler ultrasound is used currently in decompression research for the evaluation of venous gas emboli (VGE). Estimation of heart rate from post-dive Doppler ultrasound recordings can provide a tool for the evaluation of physiological changes from decompression stress, as well as aid in the development of automated VGE detection algorithms that relate VGE presence to cardiac activity. Method: An algorithm based on short-term autocorrelation was developed in MATLAB to estimate the heart rate in post-dive precordial Doppler ultrasound. The algorithm was evaluated on 21 previously acquired and labeled precordial recordings spanning Kisman-Masurel (KM) codes of 111–444 (KM I–IV) with manually derived instantaneous heart rates. Results: A window size of at least two seconds was necessary for robust and accurate instantaneous heart rate estimation with a mean error of 1.56 ± 7.10 bpm. Larger window sizes improved the algorithm performance, at the cost of beat-to-beat heart rate estimates. We also found that our algorithm provides good results for low KM grade Doppler recordings with and without flexion, and high KM grades without flexion. High KM grades observed after movement produced the greatest mean absolute error of 6.12 ± 8.40 bpm. Conclusion: We have developed a fully automated algorithm for the estimation of heart rate in post-dive precordial Doppler ultrasound recordings.

Agreement between ultrasonic bubble grades using a handheld self-positioning Doppler product and 2D cardiac ultrasound.

Intravascular bubble load after decompression can be detected and scored using ultrasound techniques that measure venous gas emboli (VGE). The aim of this study was to analyse the agreement between ultrasonic bubble grades from a handheld self-positioning product, the O'Dive™, and cardiac 2D ultrasound after decompression. VGE were graded with both bilateral subclavian vein Doppler ultrasound (modified Spencer scale) and 2D cardiac images (Eftedal Brubakk scale). Agreement was analysed using weighted kappa (Kw). Analysis with Kw was made for all paired grades, including measurements with and without zero grades, and for each method's highest grades after each dive. A total of 152 dives yielded 1,113 paired measurements. The Kw agreement between ultrasound VGE grades produced by cardiac 2D images and those from the O'Dive was 'fair'; when zero grades were excluded the agreement was 'poor'. The O'Dive was found to have a lower sensitivity to detect VGE compared to 2D cardiac image scoring. Compared to 2D cardiac image ultrasound, the O'Dive yielded generally lower VGE grades, which resulted in a low level of agreement (fair to poor) with Kw.

A Rare Case of Transesophageal Echocardiography Probe-Induced Tongue Ulcer

AbstractTransesophageal echocardiography (TEE) is a commonly used diagnostic and monitoring modality in anesthetic practice. It is used in neurosurgery for monitoring cardiac function and detecting venous air embolism. TEE is a semi-invasive procedure and is considered to be reasonably safe with a few complications. During neurosurgical cases, access to the head end is limited and TEE can cause injury due to prolonged contact. These injuries can be noticed only at the conclusion of the surgery. We report a rare case of tongue ulcer caused due to the use of TEE in a sitting neurosurgical procedure with a complete resolution.

Gas Pressure From the Endoscope: An Unexplored Contributor to Morbidity and Mortality?

Background It has been shown that the incidence of venous air embolism and venous carbon dioxide (CO2) embolism is high during endoscopic retrograde cholangiopancreatography (ERCP). We examined insufflating gas flow and maximum pressure produced by three types of commonly used endoscopes because we could not readily locate technical data for endoscope gas flow and maximum emitted pressure in the manufacturer's manuals. Methods We tested the Olympus GIF-Q180 used for esophagogastroduodenoscopy, the CF-Q180 used for colonoscopy, and the TJF-Q180 used for ERCP (Olympus America Inc., Center Valley, Pennsylvania). Under three different clinical gas insufflation scenarios, we measured in vitro maximum gas pressure transduced from a closed space created at the endoscope tip in a worst-case scenario analysis. Results We showed that it is readily possible to generate a pressure (>5-30 times normal central venous pressure) in the air space at the tip of all three endoscopes when insufflation is activatedand the gas egress is limited. Conclusions These findings shedadditional light on in vivo occurrences of gas embolism during gastrointestinal endoscopy. We postulate that in addition to using exclusively CO2 as the insufflating gas, the risk of gas embolism can be further diminished by regulating insufflating gas pressure at the tip of endoscopes.

NONCARDIOGENIC PULMONARY EDEMA AS SEQUEL OF VENOUS AIR EMBOLISM IN A CASE OF OPERATIVE HYSTEROSCOPY – A CASE REPORT.

Hysteroscopy is minimally invasive procedure performed widely for diagnosis and treatment of intrauterine and endocervical pathologies.Venous air embolism,though rare complication,is catastrophic if encountered.We report one such case of venous air embolism leading to non-cardiogenic pulmonary edema encountered by us during hysteroscopic uterine septum resection done for infertility under general anaesthesia.Quick identification,preventing further gas entry and timely intervention saved our patient.

Resection of posterior fossa tumors in the semi-sitting position in children younger than 4 years of age

PurposeThe semi-sitting position for resection of posterior fossa tumors is a matter of ongoing debate. Here we report about our experience with this approach in children younger than 4 years of age.MethodsWe retrospectively analyzed data of children younger than 4 years of age operated on in our institution in the semi-sitting position over a 15-year period. Patients were intraoperatively monitored for venous air embolism (VAE) by transthoracic Doppler (TTD) or transesophageal echocardiography (TEE). The severity of VAE was classified according to the Tübingen grading scale. Intraoperative incidents of VAE were recorded and the patients’ course was followed postoperatively with a special focus on possible complications.ResultsTwenty-four children (18 boys, 6 girls) were operated on in the semi-sitting position (26 operations). Mean age was 2.2 years (± 1.0), range between 0.4 and 3.9 years. External ventricular drains were inserted in 18 children with hydrocephalus preoperatively. VAE was detected in 6 instances during surgery (6/26 (23.1%)). In 3 patients with grade 1 VAE, no additional treatment was necessary. In one patient with grade 2 VAE, intracardiac air suction via the central venous catheter was performed, and in two patients with grade 4 VAE, additional cathecholamine-infusion was administered. No major intraoperative complications occurred. Postoperative CT images showed pneumocephalus in all children. In two children, small asymptomatic impression skull fractures at the site of the Mayfield pin occurred. Revision surgery was necessary in one child with a suboccipital CSF fistula.ConclusionThe semi-sitting position for resection of tumors in the posterior fossa in children younger than 4 years of age can be safely performed in experienced centers taking special caution to detect and treat potential complications in an interdisciplinary setting.

Abstract 15561: A Rare Case of Air Embolus in the Presence of Bilateral Pulmonary Emboli

Case Presentation: A 70-year-old male with cardiac risk factors, cirrhosis, stage II cholangiocarcinoma, and a right internal jugular port-a-catheter, presented to the hospital following an unwitnessed syncopal episode one day after undergoing a therapeutic paracentesis. On presentation he was hemodynamically unstable and endorsed severe substernal chest pain. Diagnostic work-up revealed large bilateral pulmonary emboli, and large amounts of intravascular gas in the right brachial vein, superior vena cava (SVC), right atrium and ventricle (Figure A). He was immediately placed on supplemental oxygen, given intravenous fluids, and started on vasopressors. He was a poor candidate for mechanical thrombectomy thus tissue plasminogen activator (tPA) was administered, and he was admitted to the medical intensive care unit for further management. Discussion: Venous air emboli occur as rare complications of trauma or intravascular procedures when air or gas enters the vasculature. Symptoms are generally non-specific making them difficult to recognize. In this patient, a central port-a-catheter had been placed two months prior for chemotherapy administration. A central line provides a direct connection between the air and the vasculature. The sub-atmospheric pressures in the SVC, where these lines often terminate, create a pressure gradient conducive to the development of air emboli. Hypovolemic states as seen in cirrhosis and pulmonary emboli) can further magnify this gradient. Interestingly, the presence of a large venous air embolism and concurrent massive bilateral pulmonary emboli, has rarely been previously reported. Caution should be taken in prevention, early detection, and treatment to avoid potentially fatal complications.

Venous air embolism after blunt thoracic trauma without additional pathology

Air embolism is a rarely encountered but potentially life-threatening medical emergency and may occur as a result of many underlying reasons, such as trauma, surgery, catheterization, iatrogenic, and misapplication. Iatrogenic causes should be kept in mind, particularly if no other pathology is detected to explain the radiological findings in the patient after invasive procedures. In this case report, we present a 28-year-old male patient with a venous air embolism after a blunt trauma without an additional pathology and the diagnosis, treatment, and follow-up period.

THERAPEUTIC MANUAL ASPIRATION OF LARGE VENOUS AIR EMBOLISM IN A PATIENT WITH SHOCK

THERAPEUTIC MANUAL ASPIRATION OF LARGE VENOUS AIR EMBOLISM IN A PATIENT WITH SHOCK

SOPHISTICATED AIR HEAD: A UNIQUE PRESENTATION OF IATROGENIC AIR EMBOLISM IN SOFT TISSUE OF THE NECK AND CHEEK

SOPHISTICATED AIR HEAD: A UNIQUE PRESENTATION OF IATROGENIC AIR EMBOLISM IN SOFT TISSUE OF THE NECK AND CHEEK