Severity Of Venous Air Embolism Research Articles

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.

Occurrence and Severity of Venous Air Embolism During Neurosurgical Procedures: Semisitting Versus Supine Position

At our institution, patients undergoing neurosurgical procedures in the posterior cranial fossa are placed either in the semisitting or in the supine position. The major risk of the semisitting positioning is a venous air embolism (VAE), which may, however, also occur in the supine position. In a prospective single-center study with 137 patients, we evaluated the occurrence of VAEs in patients in the supine and in the semisitting position during the period from January 2014 until April 2015. All patients were monitored for VAE by the use of a transesophageal echocardiography (TEE). In total, 50% of the patients experienced a VAE (56% of these patients underwent surgery in the semisitting and 11% in the supine position). In total, 86% of the VAEs were detected by the use of a TEE and did not lead to any changes in the end-expiratory CO2. We only observed VAEs with a decrease in end-expiratory CO2 in the semisitting position. However, none of the patients had any hemodynamic changes due to the VAE. The semisitting position with TEE monitoring and a standardized protocol is a safe and advantageous technique, taking account of a significant rate of VAEs. VAEs also occur in the supine position, but less frequently.

Late venous air embolism following insertion of Mayfield head pins.

Dear Editor, Venous air embolism (VAE) is not an uncommon event during neurosurgical procedures. It is an iatrogenic complication that occurs when air from the atmosphere enters into the systemic circulation specifically when the surgical site is above the level of heart producing a sub-atmospheric pressure in the open veins. A 27-year-old male diagnosed as a case of fronto-temporo-parietal meningioma was posted for craniotomy and excision under general anesthesia. His Glasgow Coma Scale [GCS] was 15, and no neurological deficit was present. All laboratory investigations were within normal limits. His magnetic resonance imaging was suggestive of large well-defined lesion in left Sylvian fissure, extending into left basal cistern with mass effect. Following anesthesia induction, a Mayfield pin was used to stabilize the head of the patient in a supine position. The pin was removed and reinserted by the surgeon to improve the surgical access. Half an hour later, the surgeon repositioned the patient with head end elevated by 30 degree. We observe a sudden fall in end-tidal carbon dioxide concentration [EtCO2] from 30 to 19 mmHg with a drop of oxygen saturation from 100% to 95%. Rest of the vital parameters including heart rate and blood pressure demonstrated no change from baseline. We started the management with administration of 100% oxygen and intravenous fluids. We could aspirate 4–5 ml of air through the central venous line catheter [Arrow triple lumen central venous catheter, 7 French sizes, and 16-centimeter length]. We confirmed the central venous line position with electrocardiogram as a guide. The superior vena cava – right atrium junction positioning of the central venous line was confirmed with a tall P wave, which was equal to R wave height. The time frame between the event and air aspiration was one and half minutes. Within 1–2 min of air aspiration, oxygen saturation returned back to normal and EtCO2 rose up to 25 mmHg from 19 mmHg. No further episodes of VAE occurred during surgery. Mayfield head pin is commonly used in neurosurgical patients to keep the head stable during surgery. The literature is scarce in case reports showing an association of VAE and Mayfield head pins in adult patients.[12] Ture H et al. observed that the rate and severity of VAE were significantly lower in patients with 30-degree head elevation than in patients with 45-degree head elevation undergoing craniotomy in semi-sitting position.[3] This was a case of late VAE during repositioning of patient possibly following air entrainment through diploic veins injured at first attempt of pin insertion. In our case, we could not find any other possible explanation for this sudden decrease in EtCO2 except for the traumatized initial skull pin site being culprit for air entrainment after a change in position. At this time point, the surgery was not started and anesthetic depth was well maintained. The proper scanning of the surgical site by a surgeon before pin insertion, avoidance of sudden change in patient positioning, and proper suturing of the initial traumatized pin insertion site could avert this iatrogenic complication. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

The impact of transesophageal echocardiography based protocol for management of adults in the sitting position on the incidence of clinically significant venous air embolism

The purpose of the study was to evaluate the impact of transesophageal echocardiography (TEE) – based protocol for management of adults in the sitting position during elective neurosurgical interventions on the incidence of clinically significant venous air embolism (VAE). Material and Methods ― The study involved 155 adult neurosurgery patients (70 in prospective group and 85 in retrospective group). Surgery in both groups was done in the sitting position. In the prospective group TEE-based protocol was used. Retrospective group served as control. The primary endpoint was considered to be a decrease in the frequency of clinically significant VAE in the prospective group in comparison with the retrospective one. In the prospective group, VAE with Tuebingen grade 3-5 was considered clinically significant. The PFO incidence and severity and the effect of the number of episodes of VAE per case on its maximum severity during surgery were also analyzed. Any complication in the postoperative period believed to be associated with the position of the patient on the table during the surgery was recorded. Results ― The incidence of the clinically significant VAE in the retrospective group was 23.5% (95% CI 15-34) and was 16.4% higher than the frequency in the prospective group (chi-square=7.6197, df=1, p=0.005). 50% (95% CI 38-62) of patients in prospective group developed VAE during surgery. In 16 cases, the number of episodes was more than one. The number of episodes of VAE in the observation was reliably associated with the maximum severity of VAE during the observation (Z=4.11; p<0.001). A moderate strength relationship was determined between them (SomersDelta=0.43; 95% CI 0.17-0.7). Not a single case of paradoxical air embolism was detected in a series of observations. None of the patients has got a neurological deficit or cardiopulmonary complications associated with the position on the surgical table in the postoperative period. Pneumocephalus was found in 100% of cases on head computed tomography, which, however, did not need surgical treatment. PFO in the prospective group was detected in 62% (95% CI 52-73) of patients. In 25% (95% CI 16-35), shunting was significant. A large PFO without Valsalva maneuver was detected in 12.5% (95% CI 6-21) of cases. Conclusion ― The use of the TEE-based protocol for the management of adult patients in a sitting position during elective neurosurgical interventions can reduce the incidence of clinically significant VAE.

Jugular Bulb Pressure in Surgery of Patients in Sitting Position

Background. The pressure in brain sinuses (BSP) is used to monitor the effectiveness of various methods of prevention and treatment of venous air embolism (VAE) during surgeries in patients in the sitting position. A simpler and more approachable way is to measure the pressure in the superior bulb of the jugular vein (JBP), which accurately reflects the BSP. The dependence of the frequency and severity of VAE in JBP, however, has not been investigated, and the data on the effect of various methods of prevention and treatment of VAE on JBP are either insufficient or contradictory. The study was aimed to determine the dynamics of the JBP when bringing the patient to a sitting position, its relation with the severity of the VAE and to assess the effect of right atrium pressure (RAP), positive end expiratory pressure (PEEP) and decreased minute pulmonary ventilation (MPV) on it. Material and methods . The prospective study included 66 people who underwent intracranial surgery in a sitting position. In addition to the standard monitoring under general anesthesia with artificial lung ventilation, the superior bulb of the jugular vein and the right atrium were catheterized, and the esophagus was intubated with transesophageal echocardiography sensor. JBP was measured in a supine and sitting position and examined in relationship to RAP. In patients with JBP<0 mm Hg, its dynamics was evaluated at PEEP<0 cm H20 and MPV with end-tidal carbon dioxide (etCO 2 )=44 mm Hg, PEEP=15 cm H 2 0 and MPV with etCO 2 =36 mm Hg. The Tuebingen scale (Tuebingen VAE) was used to determine the severity of VAE. Results. After bringing the patient to the sitting position the JBP significantly (W=2137.5; p<0.001) decreased by an average of 8 mm Hg, while in 11 (16.7%; 95% CI: 8.6-27, 8) cases it remained positive. No correlation was found between the RAP and JBP in the supine position (Z =-0.08225; p=0.9344) and in the sitting position (Z=1.2272, p=0.2198). The VAE frequency was 51% (95% CI 38.8-64). In patients with JBP <0 mm Hg, the frequency and severity of VAE was significantly higher than with JBP≥1 mm Hg (chi-square=4.37; df=1; p=0.036 and Z=2.47, p=0.015, respectively). Significant changes of JBP when PEEP 15 cm H 2 O and MPV with etCO 2 =36 mm Hg were not found (Z = -0.9784, p=0.3964 and Z=-1.3324, p=0.2305 respectively). Conclusion. 1. The negative JBP after bringing the patient to the sitting position is accompanied by an increase in the frequency and severity of VAE. 2. In patients in a sitting position, the correlation between RAP and JBP was not found. 3. Isolated PEEP and changes in ventilation do not lead to an increase in JBP.

The relationship between end-expired carbon dioxide tension and severity of venous air embolism during sitting neurosurgical procedures – A contemporary analysis

Study objectiveDetermine if changes in expired carbon dioxide tension correlate with the severity of venous air embolism (VAE) associated hemodynamic changes in humans. DesignRetrospective case series. SettingA single academic medical center with high-volume neurosurgical practice. PatientsOne hundred forty seven adult patients having neurosurgical procedures performed with general anesthesia in the sitting position who experienced venous air embolism. InterventionsIdentification of documentation of venous air embolism by either precordial Doppler sonography or transesophageal echocardiography. MeasurementRetrospective determination of changes in end-expired carbon dioxide (EECO2) changes associated with venous air embolism. Main resultsGreater absolute and relative decreases in end-expired carbon dioxide tension were associated with greater hemodynamic manifestations of venous air embolism. However, based on receiver operating characteristic curve analysis, the absolute and relative changes in EECO2 have moderate utility for predicting the severity of hemodynamic consequences of venous air embolism as area under the curve for absolute and relative carbon dioxide tensions were 0.7654 and 0.7263, respectively. ConclusionsGreater magnitude of decreases in EECO2 is associated with hemodynamically-significant VAE in mechanically-ventilated patients. However, the magnitude of changes may have limited utility to diagnose VAE or exclude the diagnosis of VAE in patients with unexplained intraoperative hypotension.

Effect of the degree of head elevation on the incidence and severity of venous air embolism in cranial neurosurgical procedures with patients in the semisitting position.

OBJECTIVE The semisitting position of a patient confers numerous advantages in various neurosurgical procedures, but venous air embolism is one of the associated complications of this position. To date, no prospective studies of the relationship between the degree of head elevation and the rate and severity of venous air embolism for patients undergoing a procedure in this position have been performed. In this study, the authors compared changes in the severity of venous air embolism according to the degree of head elevation (30° or 45°) in patients undergoing an elective cranial neurosurgical procedure in the semisitting position. METHODS One hundred patients undergoing an elective infratentorial craniotomy in the semisitting position were included, and each patient was assigned to 1 of 2 groups. In Group 1, each patient's head was elevated 30° during surgery, and in Group 2, each patient's head elevation was 45°. Patients were assigned to their group according to the location of their lesion. During surgery, the standard anesthetic protocol was used with total intravenous anesthesia, and transesophageal echocardiography was used to detect air in the blood circulation. Any air embolism seen on the echocardiography screen was classified as Grade 0 to 4. If multiple events occurred, the worst graded attack was used for statistical analysis. During hemodynamic changes caused by emboli, fluid and vasopressor requirements were recorded. Surgical and anesthetic complications were recorded also. All results were compared statistically, and a p value of < 0.05 was considered statistically significant. RESULTS There was a statistically significant difference between groups for the total rates of venous air emboli detected on transesophageal echocardiography (22.0% [n = 11] in Group 1 and 62.5% [n = 30] in Group 2; p < 0.0001). The rate and severity of air embolism were significantly lower in Group 1 than in Group 2 (p < 0.001). The rates of clinically important venous air embolism (Grade 2, 3, or 4, venous air embolism with decreased end-tidal carbon dioxide levels and/or hemodynamic changes) were 8.0% (n = 4) in Group 1 and 50.0% (n = 24) in Group 2 (p < 0.0001). There was no association between the rate and severity of venous air embolism with patient demographics (p > 0.05). An association was found, however, between the rate of venous air embolism and the type of surgical pathology (p < 0.001); venous embolism occurred more frequently in patients with a meningioma. There were no major surgical or anesthetic complications related to patient position during the postoperative period. CONCLUSIONS For patients in the semisitting position, an increase in the degree of head elevation is related directly to a higher rate of venous air embolism. With a 30° head elevation and our standardized technique of positioning, the semisitting position can be used safely in neurosurgical practice.

Craniotomy in sitting position: anesthesiology management.

Sitting position to surgically approach posterior fossa disorder continues to be the first choice for some neurosurgical teams. We underwent a literature research for recent published studies involving neurosurgical patients operated on in this position. Preoperative evaluation, anesthetic technique, intraoperative monitoring, detection and treatment of venous or arterial air embolism episodes, and all the reported complications were recorded. A modified semisitting (lounging) position aiming to create a positive pressure in the transverse and sigmoid sinuses, with lower head and higher legs positioned above the top of the head, decreases the incidence and severity of venous air embolism. Hyperventilation, compromising cerebral blood flow, has to be avoided during a sitting position. Precordial Doppler or transesophageal echocardiography monitoring improves the detection of small venous air embolism enabling its early treatment and diminishing its consequences. Patients with known patent foramen ovale can be operated on in a sitting position, under strict protocol, with few reported clinical venous air embolism and no paradoxical air embolism. Sitting position for neurosurgical procedures may be a well tolerated approach for the patient if neurosurgeons and neuroanesthesiologists undergo a strict team protocol, including all necessary monitoring and meticulously followed.

Hepatic Resection by Cavitron Ultrasonic Surgical Aspirator Increases the Incidence and Severity of Venous Air Embolism

Hepatic Resection by Cavitron Ultrasonic Surgical Aspirator Increases the Incidence and Severity of Venous Air Embolism

Hepatic Resection by the Cavitron Ultrasonic Surgical Aspirator?? Increases the Incidence and Severity of Venous Air Embolism

The Cavitron Ultrasonic Surgical Aspirator (CUSA) is an innovative tool for resecting hepatic parenchyma, which reduces intraoperative blood loss and perioperative morbidity. We designed this study to compare the incidence and severity of venous air embolism (VAE) detected via transesophageal echocardiography (TEE) during hepatic resection by using either the clamp-crushing method or the CUSA method. Fifty patients scheduled for hepatic resection were randomly assigned to receive hepatic resection by the clamp-crushing method (CC group) or by CUSA (CUSA group). After the induction of anesthesia, the TEE probe was inserted into the patient's esophagus. An independent anesthesiologist graded VAE shown in the 4-chamber view of TEE. All patients in the CUSA group showed VAE during hepatic resection and 44% of the patients had air embolism filling more than half the right heart diameter. In CC group, 68% of the patients showed VAE, which filled less than half the right heart diameter. There were no significant differences in hemodynamics and end-tidal CO2 partial pressure between the two groups. In conclusion, hepatic resection by CUSA increases the incidence and severity of VAE. This study demonstrated that venous air embolism during hepatic resection was more frequent and severe when using the Cavitron Ultrasonic Surgical Aspirator. Although we found no evidence of hemodynamic compromise, increased venous air embolism may increase the risk of paradoxical embolism in patients with liver cirrhosis.

The Incidence and Severity of Venous Air Embolism Determined by Transesophaseal Echocardiography in Hepatic Resection Using a Cavitron Ultrasonic Surgical Aspirator Dong

Background: A new technique resecting the hepatic parenchyma without inflow occlusion using a Cavitron Ultrasonic Surgical Aspirator (CUSA) reduces intraoperative blood loss and perioperative morbidity. This study was designed to identify the incidence and severity of venous air embolism (VAE) using transesophaseal echocardiography (TEE) in hepatic resection using CUSA. Methods: Forty patients undergoing hepatic resection using CUSA of ASA class 1 and 2 were selected. After insertion of an epidural catheter for postoperative analgesia, all patients were anesthetized with sevoflurane in 50% air/. After the induction of anesthesia, A TEE probe was inserted into the esophagus. Blood pressure, heart rate, central venous pressure, end tidal , and arterial carbon dioxide tension were recorded after induction, and during and after hepatic resection. During hepatic resection, an anesthesiologist evaluated the degree of VAE by transesophageal echocardiography in the 4-chamber view. Results: The mean time of using CUSA was 65.3 24.4 minutes. Of 40 patients, 9 had VAE grade I, 14 grade II, 14 grade III, and 3 grade IV. However, no significant difference was observed in hemodynamics or PaCO2 after induction, or during or after hepatic resection. The mean amount of blood loss was 887.0 ml 598.8 ml and the mean transfused amount was 123.1 351.3 ml. Conclusions: All patients showed air embolism during hepatic resection with CUSA. Serious complications associated with air embolism would occur in patients with an undiagnosed intracardiac right to left shunt. Therefore, meticulous monitoring by transesophageal echocardiography might be recommended in hepatic resection with CUSA.

Incidences of venous air embolism and patent foramen ovale among patients undergoing selective peripheral denervation in the sitting position.

The incidence and severity of venous air embolism (VAE), a potentially fatal complication, among patients undergoing selective peripheral denervation in the sitting position have never been clearly established. We designed this retrospective study to assess the incidence and severity of VAE, the incidence of paradoxical air embolism, and the occurrence of patent foramen ovale, as detected with transesophageal echocardiography, as well as the effects of its detection on patient treatment. After institutional review board approval, data were collected from the charts of all patients who underwent selective peripheral denervation at our institution between 1988 and 2001. The severity of VAE was assessed by using a 5-point scale. Data for 342 patients were available for analyses. Seven patients exhibited VAE, yielding an incidence of 2%. The severity of VAE was 2/5 for three patients, 3/5 for three patients, and 4/5 for one patient. Air could be aspirated from the central venous catheter for three patients. No deaths occurred. Among the 96 transesophageal echocardiographic examinations performed, 5 cases of patent foramen ovale were detected (5.2%). For those patients, surgery was performed in the prone or park-bench position. No paradoxical air embolism was detected. This is the first large study to directly assess the incidence and severity of VAE among patients undergoing selective peripheral denervation in the sitting position. We recommend that the detection of a patent foramen ovale prompt a change in position for this surgical procedure.

Venous air emboli occur during release of positive end-expiratory pressure and repositioning after sitting position surgery.

We studied the effect of positive end-expiratory pressure (PEEP) release and positioning on the occurrence of venous air embolism (VAE). Eighteen consecutive patients (8 women, 10 men; ASA grade I-III) undergoing neurosurgery in the sitting position were studied. After induction of anesthesia ventilation was controlled with a PEEP of 5 cm H(2)O in an oxygen-air gas mixture. A transesophageal echocardiographic (TEE) probe was inserted. Preoperatively, a patent foramen ovale was excluded in all patients. TEE monitoring was performed during surgery, during PEEP release at the end of surgery with the patient still in the sitting position, and during change of the patient position into the supine position. The severity of VAE was differentiated as follows: grade 1 = only microbubbles; grade 2 = microbubbles and decrease of end-tidal carbon dioxide partial pressure (PETCO(2)) by more than 1.5 mm Hg; grade 3 = microbubbles combined with a decrease of PETCO(2) by more than 1.5 mm Hg, and a decrease of mean arterial blood pressure by at least 20 mm Hg. During surgery, VAE with a grade of 1, 2 or 3 occurred in 7, 4, and 2 patients, respectively. After PEEP release, VAE of grades 1, 2, and 3 were observed in 7, 2, and 1 patients, respectively. During repositioning from sitting to supine position, VAE of grades 1, 2, and 3 was observed in 6, 1, and 1 patients, respectively. The patient with VAE grade 3 needed inotropic support until 2 h after surgery to maintain sufficient blood pressure. No patient showed any sign of paradoxical arterial embolism or cardiac dysfunction. We conclude that VAE occurs not only during surgery in the sitting position, but also with release of PEEP and during repositioning to the supine position. This study shows that venous air embolism (VAE) occurs not only during surgery in the sitting position but also during positive end-expiratory pressure release and repositioning of the patient into the supine position. Continuous monitoring for VAE should be performed until the patient is returned to the supine position.

Anesthesia and Surgery in the Seated Position

Because controversy exists regarding continued use of the seated position for neurosurgical procedures, this prospective (1981-1983) and retrospective (1972-1981) analysis of 554 seated patients was done to establish the incidence and severity of venous air embolism (VAE) related to type of surgical procedure and anesthetic technique; to examine the impact of specific monitoring practices on detection, morbidity, and mortality; and to establish the incidence of other complications related to the seated position (hypotension, quadriplegia, and arterial air embolism (AAE)). The overall morbidity and mortality related to the seated position was 1% (2 VAE, 1 AAE, 2 hypotension, 1 myocardial infarction) and 0.9% (1 VAE, 1 AAE, 2 hypotension, 1 quadriplegia), respectively. There has been no mortality since 1975. N2O did not seem to increase the incidence or severity of VAE. The seated position is safe in experienced hands if appropriate surgical and anesthetic skills are exercised in patient selection and management. Caution is advised in patients with atherosclerotic cardiovascular disease, severe hypertension, cervical stenosis, and right to left intracardiac shunts.

Anesthesia and surgery in the seated position: analysis of 554 cases.

Because controversy exists regarding continued use of the seated position for neurosurgical procedures, this prospective (1981-1983) and retrospective (1972-1981) analysis of 554 seated patients was done to establish the incidence and severity of venous air embolism (VAE) related to type of surgical procedure and anesthetic technique; to examine the impact of specific monitoring practices on detection, morbidity, and mortality; and to establish the incidence of other complications related to the seated position (hypotension, quadriplegia, and arterial air embolism (AAE)). The overall morbidity and mortality related to the seated position was 1% (2 VAE, 1 AAE, 2 hypotension, 1 myocardial infarction) and 0.9% (1 VAE, 1 AAE, 2 hypotension, 1 quadriplegia), respectively. There has been no mortality since 1975. N2O did not seem to increase the incidence or severity of VAE. The seated position is safe in experienced hands if appropriate surgical and anesthetic skills are exercised in patient selection and management. Caution is advised in patients with atherosclerotic cardiovascular disease, severe hypertension, cervical stenosis, and right to left intracardiac shunts.