Venous Air Embolism Research Articles

A human cadaveric model for venous air embolism detection tool development.

A human cadaveric model combining standard lung protective mechanical ventilation and modified cardiac bypass techniques was developed to allow investigation into automated modes of detection of venous air emboli (VAE) prior to in vivo human or animal investigations. In this study, in order to create an artificial cardiopulmonary circuit in a cadaver that could mimic VAE physiology, the direction of flow was reversed from conventional cardiac bypass. Normal saline was circulated in isolation through the heart and lungs as opposed to the peripheral organs by placing the venous cannula into the aorta and the arterial cannula into the inferior vena cava with selective ligation of other vessels. Mechanical ventilation and this reversed cardiac bypass scheme allowed preliminary detection of VAE independently but not in concert in our current simulation scheme due to pulmonary edema in the cadaver. A limited dissection approach was used initially followed by a radical exposure of the great vessels, and both proved feasible in terms of air signal detection. We used electrical impendence as a preliminary tool to validate detection in this cadaveric model however we theorize that it would work for echocardiographic, intravenous ultrasound or other novel modalities as well. A cadaveric model allows monitoring technology development with reduced use of animal and conventional human testing.

Fatal Consequences of Head Trauma: A Case Report of Venous Air Embolism Complicated by Substance Abuse and Liver Disease

Fatal Consequences of Head Trauma: A Case Report of Venous Air Embolism Complicated by Substance Abuse and Liver Disease

Right-to-left-shunts in patients scheduled for neurosurgical intervention in semi-sitting position – a literature review based on two case scenarios

BackgroundNeurosurgery performed in the semi-sitting position provides advantages for certain procedures. However, this approach is associated with potential complications, particularly venous air embolism. Due to typically negative venous pressure at the wound site, air can be drawn into the veins. This risk is especially high in patients presenting with an intra- or extracardiac right-to-left-shunt. Transoesophageal echocardiography can be used to detect a patent foramen ovale or other possible pulmonary-systemic shunt before placing the patient in the sitting position.Case presentationIn this report, we present two young patients undergoing scheduled microsurgical vestibular schwannoma removal in a semi-sitting position who were diagnosed with congenital heart defects during routine perioperative assessment to detect possible intracardiac right-to-left shunts, using pre- and intraoperative transesophageal echocardiography (TEE) and additionally conducting an agitated saline bubble study under Valsalva manoeuvre. Patient A was diagnosed with a persistent left superior vena cava and Patient B with an unroofed coronary sinus (UCS). These findings confronted the anesthesiological and surgical teams with difficult individual decisions regarding further perioperative management.ConclusionsPerioperative transesophageal echocardiography is a diagnostic tool to both detect intraoperative position-related air embolisms and to rule out intracardiac right-to-left shunts, e.g. a patent foramen ovale, in order to decide for or against a (semi-)sitting position. Depending on the surgical circumstances a semi-sitting positioning of patients presenting with an intracardiac right-to-left-shunt, e.g. a PFO, can be feasible in individual cases if there is an implemented therapeutic algorithm to immediately terminate significant venous air entry. However, since certain other intra- or extracardiac right-to-left-shunts, such as here presented PLSVC or UCS, are rare, there is no definitive way of estimating the amount of entered air through detected shunts or anomalous vessels. Therefore, it is recommended to avoid a (semi-)sitting position in favour of a lateral or prone position for a patient undergoing intracranial surgery, once the perioperative TEE shows air bubbles in the left atrium or ventricle whose origins cannot be defined solely through TEE for certain in order to ensure patient safety by minimizing the risk of intraoperative paradoxical air embolisms.

Knowledge and Practices Regarding Prevention of Central Venous Catheter Removal-Associated Air Embolism: A Survey of Nonintensive Care Unit Medical and Nursing Staff.

Air embolism is a potentially serious complication of central venous catheter (CVC) use. While CVC insertion is usually performed by a trained specialist, extraction is frequently the responsibility of junior staff members. This complication can be easily prevented by following several simple measures described in common guidelines. We conducted a single-center survey to assess knowledge and practices concerning the prevention of air embolism associated with CVC removal among healthcare workers from nonintensive care units. The correct answers to the questionnaire were determined according to best-practice recommendations for CVC removal. Based on a comparison of the total sum of correct answers between the categories of groups, factors that predicted the level of knowledge were identified using an independent sample t test. Of the 156 respondents, one-third were unfamiliar with air embolism as a complication of CVC extraction. Almost 80% were unaware of the existence of a CVC removal protocol. Almost half of respondents did not follow guidelines regarding patient position when removing a CVC, 72% did not ask the patient to perform the Valsalva maneuver during the procedure, and 54% did not ask the patient to remain supine after the procedure. Adherence to the protocol was correlated with professional experience, with a lower level among those with experience of less than 1 year and, particularly, among interns. Our survey revealed inappropriately low awareness of CVC removal-associated air embolism risk and low familiarity with CVC removal best-practice recommendations among nonintensive care unit healthcare workers. Staff members with experience of less than 1 year, including interns, were found to have a lower level of knowledge. These findings emphasize the importance of development and distribution an internal hospital protocol and the integration of educational intervention into a preliminary internship program.

Exploring anesthesia-related complications in pediatric neurosurgery: a comparative analysis of the sitting and park-bench positions.

The purpose of this study is to analyze the sitting position and the park-bench position for intra-anesthesia complications in pediatric patients undergoing neurosurgery for posterior fossa lesions. Our goal is to highlight the risks associated with each of these positions under general anesthesia to aid in clinical decision making for optimal patient outcomes with regard to postoperative complications. We retrospectively reviewed 41 pediatric patients (1 to 18 years old) undergoing posterior fossae surgery in the sitting (32) and park-bench (9) positions between January 2015 and December 2021. The majority of patients (15) who underwent surgery in the sitting position had fourth ventricular tumors (28.12%) and cerebellopontine tumors (18.76%) that required the sitting position. Of 32 patients operated on in the sitting position, 23 (71.78%) developed anesthetic complications, compared to 8 patients in the park-bench group (88.89%). Venous air embolism occurred in only 6.25% of patients in the sitting group. Compared to the sitting position, no cases of gas embolism were documented in the park-bench position. However, transient episodes of gas embolism cannot be excluded due to the higher incidence of hemodynamic instability (44.44%), need for additional fluid therapy (44.44%) and vasopressor support (11.11%), decreased CO2 (22.22%) and oxygen desaturation (22.22%). Patients who underwent surgery in the sitting position had a longer duration of surgery [247.5 min IQR (172.75 - 325.25)] and a longer duration of anesthesia [331 min IQR (237.5 - 423.25)]. Pneumocephalus (4, 12.5%) and postoperative hematoma (3, 9.38%) were the most common postoperative complications in patients who underwent surgery in the sitting position. In the park-bench group, three patients had postoperative complications, including postoperative hematoma (2, 25%) and hydrocephalus (1, 12.5%). The incidence of anesthetic complications is lower in the sitting position compared to the park-bench position. Although there was no documented gas embolism in the park-bench position, the lower rate of venous air embolism in the sitting position may suggest a better control or a lower risk in this position. However, the sitting position has a less frequent occurrence of hemodynamic instability than the park-bench position.

Cardiac Output Directly Influences Intracardiac Air After Venous Air Embolism: An Echocardiographic Model Comparing Position Change on Intracardiac Air Bubble Clearance.

Venous air embolism (VAE) can cause significant morbidity and mortality. Prevention and management of VAE include cessation of air entrainment, positioning changes, and hemodynamic support. The degree to which position change and cardiac output (CO) moderate resolution of intracardiac air has not been rigorously studied using contemporary transesophageal echocardiography (TEE). This observational cohort-type study aimed to identify the effect of supine vs sitting positioning on the movement and resolution of intracardiac air. In 20 patients undergoing seated neurosurgery, central venous air aspiration catheters were placed through the median basilic vein. TEE was used to estimate the time required for clearance of agitated microbubbles from the right atrium and ventricle in both the supine and sitting position. Estimates of CO were also obtained echocardiographically in each position. Average clearance time was faster in the sitting vs the supine position with no significant difference in CO. A negative correlation between CO and right atrial clearance time across all patients was demonstrated with a Pearson coefficient of -0.4 (95% CI -0.07, -0.65) with P = .02. During VAE, both patient position and CO can significantly affect how bubbles move through intracardiac chambers. However, augmenting CO during VAE may be clinically more feasible, efficient, and productive than changing positioning-especially during crises unless the changing in position is intended to halt the entrainment of air. Further TEE studies of intravascular air movement affected by other position changes (lateral, reverse Trendelenburg) and vasopressors should be considered.

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.

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

BackgroundThe 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.MethodsWe 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.ResultsThe 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).ConclusionThe 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.

Perioperative venous air embolism during transurethral resection of prostate

Perioperative venous air embolism during transurethral resection of prostate

Systemic venous air embolism after percutaneous lung biopsy.

Systemic venous air embolism after percutaneous lung biopsy.

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

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. 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. 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. 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.

Suicide by an Electric Power Drill and Spade Drill Bit: An Unusual Mechanism of Death.

Self-inflicted penetrating brain injuries with drills have been reported but are uncommon and typically involve the use of conventional drill bits. We report an unusual case of a 56-year-old man with a history of psychiatric illness who completed suicide using an electric drill and spade-type drill bit. Multiple superficial scalp and deeper bony injuries were sustained, although without breach of the dura, and death was not from brain injury, but secondary to venous air embolism related to entrainment of air into diploic vessels.

Eccentric exercise before a 90min exposure at 24,000ft increases decompression strain depending on body region but not total muscle mass recruited.

Eccentric upper-body exercise performed 24h prior to high-altitude decompression has previously been shown to aggravate venous gas emboli (VGE) load. Yet, it is unclear whether increasing the muscle mass recruited (i.e., upper vs. whole-body) during eccentric exercise would exacerbate the decompression strain. Accordingly, this study aimed to investigate whether the total muscle mass recruited during eccentric exercise influences the decompression strain. Eleven male participants were exposed to a simulated altitude of 24,000ft for 90min on three separate occasions. Twenty-four hours before each exposure, participants performed one of the following protocols: (i) eccentric whole-body exercise (ECCw; squats and arm-cycling exercise), (ii) eccentric upper-body exercise (ECCu; arm-cycling), or (iii) no exercise (control). Delayed onset muscle soreness (DOMS) and isometric strength were evaluated before and after each exercise intervention. VGE load was evaluated at rest and after knee- and arm-flex provocations using the 6-graded Eftedal-Brubakk scale. Knee extensor (-20±14%, P=0.001) but not elbow flexor (-12±18%, P=0.152) isometric strength was reduced 24h after ECCw. ECCu reduced elbow flexor isometric strength at 24h post-exercise (-18±10%, P<0.001). Elbow flexor DOMS was higher in the ECCu (median 6) compared with ECCw (5, P=0.035). VGE scores were higher following arm-flex provocations in the ECCu (median (range), 3 (0-4)) compared with ECCw (2 (0-3), P=0.039) and control (0 (0-2), P=0.011), and in ECCw compared with control (P=0.023). VGE were detected earlier in ECCu (13±20min) compared with control (60±38min, P=0.021), while no differences were noted between ECCw (18±30min) and control or ECCu. Eccentric exercise increased the decompression strain compared with control. The VGE load varied depending on the body region but not the total muscle mass recruited. HIGHLIGHTS: What is the central question of this study? Does exercise-induced muscle damage (EIMD) resulting from eccentric exercise influence the presence of venous gas emboli (VGE) during a 90min continuous exposure at 24,000ft? What is the main finding and its importance? EIMD led to an earlier manifestation and greater VGE load compared with control. However, the decompression strain was dependent on the body region but not the total muscle mass recruited.

Venous air emboli during esophagoscopy confirmed by computed tomographic pulmonary angiography -a case report.

Venous air emboli during esophagoscopy confirmed by computed tomographic pulmonary angiography -a case report.

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

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. 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%). 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.

Ultrasound Rounds: Intraoperative Point-of-Care Ultrasound Identifies Intracardiac Thrombus and Pulmonary Embolism Allowing for Alteration in Surgical Management.

Most of the cases demonstrating describing acute findings using point-of-care ultrasound (POCUS) have been described in emergency medicine and critical care medicine. While the use of POCUS has become more prevalent in anesthesia practice, documentation of acute findings resulting in alteration in management based on real-time ultrasound findings during pediatric anesthesia remains limited. This case highlights the use of POCUS during cardiopulmonary collapse occurring during correction of neuromuscular scoliosis. POCUS excluded the presumed diagnosis of venous air embolism and identified an intracardiac thrombus leading to the diagnosis and treatment of pulmonary embolism.

Simplified supine modified park bench / lateral decubitus position using a shoulder pad and a Mayfield head clamp for neurosurgical approach to lesions located in the occipital lobe or the posterior fossa: technical note.

Neurosurgical approach to lesions located in the occipital lobes or in the posterior fossa require very specific and time-consuming patient installations, such as the park bench position, the prone position, or the sitting position. Nevertheless, each of these position present major drawbacks regarding specific installation-related adverse events and potentially serious neurosurgical complications such as venous air embolism, iatrogenic intracranial hypertension, and supratentorial remote hematoma just to cite a few. In order to provide neurosurgeons with a simpler, physiologically-respective, easily tolerated, less time-consuming, and less provider or specific adverse events patient installation, Ochiai (1979) introduced the supine modified park-bench / lateral decubitus position. Given that this patient position has not gained wide visibility among the neurosurgical community despite its obvious numerous advantages over its classic counterparts, we provide our experience using this installation for neurosurgical approach to lesions located in the occipital lobes and in the posterior fossa.

Neuromonitoring in a Case with Midbrain Cavernoma Operated in Sitting Position: Unveiling the Complexities

AbstractThe sitting position is often utilized for mid-brain cavernoma excision due to its several surgical advantages. Intraoperative neuromonitoring aids dynamic functional assessment of neural structures in real-time. In this case report, we discuss the anesthetic management of a patient scheduled for midbrain cavernoma excision in a sitting position. Evoked potential monitoring was performed as the tumor was in proximity to cortico-spinal tracts. We used a combination of inhalational and intravenous anesthetics for the maintenance of anesthesia. Intraoperatively significant events included two episodes of venous air embolism, and loss of motor evoked potentials during the resection of the tumor. These complications were promptly recognized and managed. In the early postoperative period, the patient had motor power 3/5 in flexors of the right upper limb, which improved to normal by Day 5. Thus, good communication among anesthesiologists, neurologists, and surgeons helped identify altered evoked potential signals early, aiding the modification of dissection accordingly.

In-field use of I-VED electrical impedance sensor for assessing post-dive decompression stress in humans

Purpose: Ultrasound imaging is commonly used in decompression research to assess venous gas emboli (VGE) post-dive, with higher loads associated with increased decompression sickness risk. This work examines, for the first time in humans, the performance of a novel electrical impedance spectroscopy technology (I-VED), on possible detection of post-dive bubbles presence and arterial endothelial dysfunction that may be used as markers of decompression stress. Methods: I-VED signals were recorded in scuba divers who performed standardized pool dives before and at set time points after their dives at 35-minute intervals for about two hours. Two distinct frequency components of the obtained signals, Low-Pass Frequency-LPF: 0-0.5 Hz and Band-Pass Frequency-BPF: 0.5-10 Hz, are extracted and respectively compared to VGE presence and known flow-mediated dilation trends for the same dive profile for endothelial dysfunction. Results: Subjects with VGE counts above the median for all subjects were found to have an elevated average LPF compared to subjects with lower VGE counts, although this was not statistically significant (p=0.06), as well as significantly decreased BPF standard deviation post-dive compared to pre-dive (p=0.008). Conclusions: I-VED was used for the first time in humans and operated to provide qualitative in-vivo electrical impedance measurements that may contribute to the assessment of decompression stress. Compared to ultrasound imaging, the proposed method is less expensive, not operator-dependent and compatible with continuous monitoring and application of multiple probes. This study provided preliminary insights; further calibration and validation are necessary to determine I-VED sensitivity and specificity.

Towards real-time decompression sickness mitigation using wearable capacitive micromachined ultrasonic transducer arrays

Decompression sickness (DCS) due to inert gas supersaturation remains one of the major risks for scuba divers and can occur despite adherence to prevention schedules for staged decompression. Post-dive echocardiography for venous gas emboli (VGE) detection has low sensitivity for DCS outcome and is unable to provide real-time physiological monitoring underwater. Alternatively, we present progress towards collecting ultrasound data while at pressure and an exploration into a quantitative assessment for decompression stress. Ultrasound data of an imaging phantom were collected in a hyperbaric chamber up to 9 ATA using a Verasonics V1 system and custom capacitive micromachined ultrasonic transducer (CMUT). The DC voltage requirement for CMUT operation decreased as ambient pressure increased. Separately, a mouse model was used to simulate an extreme pressure profile and echocardiograms were collected every 20 min over 2-h post-decompression. Towards enhancement of DCS assessment, a quantitative analysis of the murine echocardiograms was implemented. Preliminary results show an increase in signal intensity within the venous blood from pre- to post-dive, indicating potential gas presence despite VGE absence. Our findings demonstrate the ability to obtain ultrasound data at pressure and a potential continuous assessment method, which may provide a practical direction for real- time decompression stress quantification.