Detection of air embolism by transesophageal echocardiography

Gas Embolism in Pediatric Minimally Invasive Surgery: Should It Be a Concern?

Introduction: Gas embolism can occur during minimally invasive surgical procedures. Its incidence and implications in infants and children are not clear. The objective of this study is to identify gas embolism with transthoracic echocardiography and its consequences in pediatric laparoscopic appendectomy. Materials and Methods: This is a descriptive observational study including children undergoing laparoscopic appendectomy. We performed transthoracic echocardiography during surgery and collected data on intraoperative hemodynamic and respiratory parameters. Results: To date, we have included 10 patients in whom intraoperative transthoracic echocardiography revealed a 50% incidence of gas embolism. All episodes of embolism were grade I or II, and the patients remained asymptomatic. The hemodynamic and respiratory parameters varied slightly during the pneumoperitoneum. Conclusions: Episodes of gas embolism in pediatric laparoscopic appendectomy appeared in up to 50% of patients. Although they were subclinical, we should be aware of the risk of serious events and take measures to maximize safety in pediatric minimally invasive surgery.

Fatal venous air embolism in the setting of hemodialysis and pulmonary hypertension: A point of care ultrasound diagnosis

Air emboli are rare and often difficult to diagnose. Transesophageal echocardiography remains the most definitive method of diagnosis, but this is not feasible in emergencies. We present a case of fatal air embolism in the setting of hemodialysis with recent evidence of pulmonary hypertension. The diagnosis was made by visualizing air in the right ventricle using bedside point of care ultrasound (POCUS). While POCUS is not routinely used for the diagnosis of air embolism, its accessibility makes it a powerful yet practical emerging tool for the diagnosis of respiratory and cardiovascular emergencies.

Characterization and comparison of a 2-, 4- and 8-MHz central venous catheter ultrasound probe for venous air emboli detection

This paper presents a concept for detection of venous air emboli inside the superior vena cava using a central venous catheter with integrated Doppler ultrasound transducer installed on the tip. Several Doppler probes each with a single insonation frequencies of 2 MHz, 4 MHz or 8 MHz are characterized and compared for usefulness in this scenario. During in vitro experiments using an artificial blood circulatory with blood mimicking fluid bubbles with defined volumes were injected and recorded as gaseous embolic events. The in vitro results of measured embolus-blood-ratio values (EBR) in respect to the air bubbles volumes and its echogenicity showed a good correlation with the simulation model of spherical cross section scattering of such air bubbles. It is shown that the probe design still needs some improvements using a 4 MHz insonation frequency to get a useable detection sensitivity in such scenario within vena cava superior. The results suggest that it is possible to estimate the air bubble volume corresponding to the EBR using such a catheter probe.

Acute air embolism caused by autotransfusion during percutaneous atrial septal defect closure: A case report

Atrial septal defect is a common congenital heart disease in adults and it is often asymptomatic. Percutaneous device closure is gaining popularity, but percutaneous repair of atrial septal defect leading to left atrial rupture and subsequent autotransfusion under high pressure leading to air embolism has not been reported yet.

European position paper on the management of patients with patent foramen ovale. Part II - Decompression sickness, migraine, arterial deoxygenation syndromes and select high-risk clinical conditions

Patent foramen ovale (PFO) is implicated in the pathogenesis of a number of medical conditions but to date only one official position paper related to left circulation thromboembolism has been published. This interdisciplinary paper, prepared with the involvement of eight European scientific societies, reviews the available evidence and proposes a rationale for decision making for other PFO-related clinical conditions. In order to guarantee a strict evidence-based process, we used a modified grading of recommendations, assessment, development, and evaluation (GRADE) methodology. A critical qualitative and quantitative evaluation of diagnostic and therapeutic procedures was performed, including assessment of the risk/benefit ratio. The level of evidence and the strength of the position statements were weighed and graded according to predefined scales. Despite being based on limited and observational or low-certainty randomised data, a number of position statements were made to frame PFO management in different clinical settings, along with suggestions for new research avenues. This interdisciplinary position paper, recognising the low or very low certainty of existing evidence, provides the first approach to several PFO-related clinical scenarios beyond left circulation thromboembolism and strongly stresses the need for fresh high-quality evidence on these topics.

Carbon dioxide embolism with severe hypotension as an initial symptom during laparoscopy: a case report

Laparoscopy is widely used because it induces minimal postoperative pain and facilitates rapid recovery. However, carbon dioxide (CO₂) embolism is a rare but potentially fatal complication of laparoscopic surgery. Earlier reports have shown that decreased end-tidal CO₂ (ETCO₂) and increased partial pressure of CO₂ might be useful indicators of CO₂ embolism. We herein report a case of CO₂ embolism after the freed bladder neck was released during laparoscopic radical prostatectomy. Sudden hemodynamic disorder and increased ETCO₂ combined with immediate arterial blood gas analysis led us to suspect CO₂ embolism, which was confirmed by the aspiration of foamy blood from the central venous catheter. The patient was successfully resuscitated and recovered well. This case illustrates that hemodynamic collapse accompanied by increased ETCO₂ can indicate CO₂ embolism.

Arterial Gas Emboli Secondary to Portal Venous Gas Diagnosed With Point-of-Care Ultrasound: Case Report and Literature Review

BACKGROUND

Portal venous gas (PVG) is a rarely observed clinical finding generally associated with intestinal ischemia. The proper clinical response to the finding of PVG depends somewhat on the setting in which it is observed. Here we describe a case in which extensive arterial gas emboli (AGE) were encountered during point-of-care ultrasound (POCUS) and subsequent computed tomography (CT) identified PVG secondary to gastric wall ischemia as the likely source.

CASE REPORT

A 69-year-old woman with history of metastatic colon cancer presented to the emergency department (ED) with altered mental status. On arrival, she was hypotensive, hypothermic, cachectic, and with abdominal distension. POCUS was performed to evaluate the source of the patient's hypotension, revealing the presence of PVG, as well as gas bubbles in all four chambers of the heart and the aorta. CT scan revealed gastric wall ischemia and confirmed the presence of significant air emboli throughout the portal venous system. Given the overall poor prognosis, the decision was made to forego further chemotherapy or surgery and the patient died later that week while under hospice care. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: AGE can occur in the setting of PVG. This may cause multi-organ failure by disrupting blood flow to organs, especially in patients with circulatory dysfunction, such as shock. Depending on the setting in which it is diagnosed, early detection of PVG may expedite earlier assessments of a patient's negative prognosis or initiation of attempted life-saving treatment. In this case report, we show that POCUS can be used to obtain an expedited diagnosis in a critically ill patient.

Suicide by air embolism introduced by means of a bicycle pump

A 64-year-old man was found dead in bed in his flat. In his right hand he held a bicycle pump to which a small-gauge cannula was attached and two fresh puncture wounds were found on his left hand. During the autopsy an air embolism of ca. 50 ml air was detected in the right ventricle of the heart by means of an aspirometer. The air embolism could not be reliably detected in a thorax radiograph taken prior to autopsy. Blood in the right ventricle was foamy. Pathological changes to organs were not found. Aside from the puncture wounds, there were no signs of externally applied mechanical force. The results of the toxicological analyses were negative.

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.

Practical conduct of open heart procedures for congenital heart lesions

Open heart surgery on infants with congenital heart lesions can be challenging not only in terms of the surgical procedure itself but also for setting up ideal conditions for safe and smooth conduct of cardiopulmonary bypass (CPB). The surgeon has to deal with a variety of lesions in a subgroup of patients who offer little room for any error. Familiarity with the principles of CPB, check lists and protocols go a long way in improving outcome in this critical group of patients.

The history of transesophageal echocardiography: the role of inspiration, innovation, and applications

Transesophageal echocardiography (TEE), which is commonly used for monitoring and diagnostic imaging during cardiovascular surgery, was originally developed by a strong desire to know what was taking place in the heart in the dark ages of cardiac surgery. The author was fortunate to be present in the midst of the development of TEE and have an opportunity to take a close look at the history of this innovation. Furthermore, the author believes that the history of TEE contains important lessons and tips for solving the problems we presently face in clinical practice. This article describes the history of TEE based on the reports in the early stage of development and discuss how inspiration and innovation was generated by a strong wish and passion to overcome problems. The development of TEE was based on the collaboration of colleagues in different fields, and an intense desire to convert ideas into reality.

"De-airing" in open heart surgery: report from the CVSAP nation-wide survey and literature review

Since the beginning of cardiac surgery, retained intracardiac air has been an important problem. While transesophageal echocardiography enabled to visualize the air and de-airing procedures have been routinely done, they appear to vary much among institutions not necessarily based on firm scientific evidence. Thus, "de-airing" was chosen as the theme of 2016 CVSAP (cardiovascular surgery and anesthesia and perfusion) symposium and a nation-wide questionnaire survey was carried out prior to it. This paper reports on its results and illustrate "the best of de-airing" based on literature review. The collection rate of the questionnaire survey was 77.9% (278/357) and 83.3% (85/102) from the major institutions of surgeons and anesthesiologists, respectively. More than 90% of both consider de-airing as important, since adverse events of air embolism were actually encountered including critical ones. Most routinely performed de-airing procedures are posture change, lung inflation and aspiration through the vent cannulae. Direct aspiration is performed in one-third of institutions. Carbon dioxide insufflation is performed in 82.5% of institutions (mostly 2-3 L/min). However, not a few surgeons are skeptical for its significance. While many surgeons are grateful for collaboration by anesthesiologists, some expect more information sharing between them. They also expect that clinical engineers understand "de-airing" better and operate the extracorporeal circulation system appropriately to avoid an occurrence of undesirable event. Some surgeons anticipated a convenient device for de-airing. Furthermore, some questions to be solved in the future were raised, including how meticulously the bubbles should be removed or how efficient carbon dioxide insufflation is.

Carbon Dioxide Embolism Associated With Transanal Total Mesorectal Excision Surgery: A Report From the International Registries

BACKGROUND

Carbon dioxide embolus has been reported as a rare but clinically important risk associated with transanal total mesorectal excision surgery. To date, there exists limited data describing the incidence, risk factors, and management of carbon dioxide embolus in transanal total mesorectal excision.

OBJECTIVE

This study aimed to obtain data from the transanal total mesorectal excision registries to identify trends and potential risk factors for carbon dioxide embolus specific to this surgical technique.

DESIGN

Contributors to both the LOREC and OSTRiCh transanal total mesorectal excision registries were invited to report their incidence of carbon dioxide embolus. Case report forms were collected detailing the patient-specific and technical factors of each event.

SETTINGS

The study was conducted at the collaborating centers from the international transanal total mesorectal excision registries.

MAIN OUTCOME MEASURES

Characteristics and outcomes of patients with carbon dioxide embolus associated with transanal mesorectal excision were measured.

RESULTS

Twenty-five cases were reported. The incidence of carbon dioxide embolus during transanal total mesorectal excision is estimated to be ≈0.4% (25/6375 cases). A fall in end tidal carbon dioxide was noted as the initial feature in 22 cases, with 13 (52%) developing signs of hemodynamic compromise. All of the events occurred in the transanal component of dissection, with mean (range) insufflation pressures of 15 mm Hg (12-20 mm Hg). Patients were predominantly (68%) in a Trendelenburg position, between 30° and 45°. Venous bleeding was reported in 20 cases at the time of carbon dioxide embolus, with periprostatic veins documented as the most common site (40%). After carbon dioxide embolus, 84% of cases were completed after hemodynamic stabilization. Two patients required cardiopulmonary resuscitation because of cardiovascular collapse. There were no deaths.

LIMITATIONS

This is a retrospective study surveying reported outcomes by surgeons and anesthetists.

CONCLUSIONS

Surgeons undertaking transanal total mesorectal excision must be aware of the possibility of carbon dioxide embolus and its potential risk factors, including venous bleeding (wrong plane surgery), high insufflation pressures, and patient positioning. Prompt recognition and management can limit the clinical impact of such events. See Video Abstract at http://links.lww.com/DCR/A961.

Venous carbon dioxide embolism during laparoscopic cholecystectomy a literature review

Laparoscopy has become the procedure of choice for routine gallbladder removal. A serious complication of this technique is the occurrence of gas emboli due to insufflation. It is associated with a high mortality rate of around 28%. The present systematic review intends to provide more insight into causes, symptoms and risk factors for this specific complication and to explore which measures should be taken to treat and prevent it. The Cochrane library and Pubmed were used as sources. Articles and their references were selected when they were related to the subject in sufficient detail. The course of this complication can vary from asymptomatic up to impairment of normal flow through the right ventricle (RV) or pulmonary artery, potentially leading to acute heart failure. The severity depends on the amount of gas, the rate of accumulation and the ability to remove the gas bubbles. It is difficult to estimate the true incidence of venous gas embolism during laparoscopic cholecystectomy as there are various diagnostic tools, each with different sensitivity. Precautions that need to be taken are: correct positioning of the needle, low insufflation pressure, low insufflation speed, screening for hypovolemia, Trendelenburg positioning, availability of intervention equipment at operation table, no placement of venous catheters during inspiration and catheter removing during expiration. Physicians need to be more aware of this harmful complication and the preventative measurements that need to be taken. As there are virtually no prospective data, future studies are needed to gain more knowledge on gas emboli during laparoscopic cholecystectomy.

Anaesthesia for Neurosurgery in the Sitting Position: A Practical Approach

Neurosurgery in the sitting position offers advantages for certain operations. However, the approach is associated with potential complications, in particular venous air embolism. As the venous pressure at wound level is usually negative, air can be entrained. This air may follow any of four pathways. Most commonly it passes through the right heart into the pulmonary circulation, diffuses through the alveolar-capillary membrane and appears in expelled gas. It may pass through a pulmonary-systemic shunt such as a probe patent foramen ovale (paradoxical air embolism); it may collect at the superior vena cava-right atrial junction. Rarely it may traverse through lung capillaries into the systemic circulation. Many monitors, such as the precordial Doppler, capnography, pulmonary artery catheter, transoesophageal echocardiography are useful for venous air embolism detection, with transoesophageal echocardiography being today's gold standard. Various manoeuvres, including neck compression and volume loading, are also useful in reducing the incidence of venous air embolism. Volume loading, in particular, is very helpful as it reduces the risk of hypotension. Other particular concerns to the anaesthetist are airway management, avoidance of pressure injuries, and the risk of pneumocephalus, oral trauma, and quadriplegia. Newer anaesthetic agents have made the choice of anaesthetic technique easier. An appreciation of the implications of neurosurgery in the sitting position can make the procedure safer.

Repeated cardiac arrest caused by an air embolism during hepatic resection: A case report

RATIONALE

Although venous air embolism (VAE) during liver operation has been reported occasionally, fatal VAE in hepatic resection is uncommon. Prompt detection of VAE by transesophageal echocardiography (TEE) is crucial for effective therapy. We describe a case of fatal VAE that caused repeated cardiac arrest during hepatic resection and was confirmed by TEE.

PATIENT CONCERNS

A 51-year-old woman with a body weight of 50 kg underwent partial liver resection due to intrahepatic duct calculus. She had a 1-year history of intrahepatic duct calculus without cardiopulmonary disease. The operation was performed under general anesthesia combined with epidural block. When the inferior vena cava was compressed, the PetCO2 level decreased abruptly from 30 to 10 mmHg, followed by a decrease in SpO2 and the development of hypotension. Her heart rate increased with ST interval elevation on electrocardiography monitoring. Ephedrine and phenylephrine were administered immediately but had little effect. Cardiac arrest occurred.

DIAGNOSES

Air embolism was detected by TEE.

INTERVENTIONS

Resuscitation was successful although cardiac arrest occurred repeatedly.

OUTCOMES

The patient returned to consciousness 6 hours postoperatively but died of multiorgan dysfunction 10 days later.

LESSONS

Fatal air embolism may happen during hepatic resection. Prompt detection of VAE by TEE is crucial for effective therapy and should always be available during hepatic resection.

Efficient Removal of Retained Intracardiac Air Utilizing Buoyancy

Retained intracardiac air has been an important issue in cardiac surgery. Although echo visualization has allowed detection of air and guided deairing procedures, adequate air removal is not always attained. Actually it has been attempted in each surgeon's manner without solid standard or evidence. Basically buoyancy is responsible for air retention as well as difficult deairing. This paper is aimed to present the author's current measures of deairing, which turn this property of air into efficient removal, as test bed for discussion on this long-standing but pending issue.

Vascular Air Embolism During Bronchoscopy Procedures- Incidence, Pathophysiology, Diagnosis, Management and Outcomes

Vascular air embolism (VAE) is a rare, but potentially fatal complication of invasive medical or surgical procedures. It is a very rare complication of bronchoscopy and is most frequently reported with therapeutic bronchoscopy with Argon plasma coagulation (APC) or neodymium-doped yttrium aluminum garnet (Nd-YAG) laser. Despite being rare, as a result of its high chance of mortality and morbidity, it is imperative that physicians have high clinical suspicion to allow for early recognition and treatment. In this article, we provide a concise review of the incidence, pathophysiology, diagnosis management and outcomes of air embolism during bronchoscopy procedures.

Air Embolism: Practical Tips for Prevention and Treatment

Air embolism is a rarely encountered but much dreaded complication of surgical procedures that can cause serious harm, including death. Cases that involve the use of endovascular techniques have a higher risk of air embolism; therefore, a heightened awareness of this complication is warranted. In particular, central venous catheters and arterial catheters that are often placed and removed in most hospitals by a variety of medical practitioners are at especially high risk for air embolism. With appropriate precautions and techniques it can be preventable. This article reviews the causes of air embolism, clinical management and prevention techniques.

Point-Of-Care Ultrasound Diagnosis of Intravascular Air After Lower Extremity Intraosseous Access

BACKGROUND

Vascular air embolism is a rare but potentially deadly phenomenon. Early diagnosis allows providers to initiate measures aimed at preventing further air entry, preventing the migration of air to the lungs, and mitigating the hemodynamic effects of pulmonary air embolism.

CASE REPORT

An emergency physician used point-of-care ultrasound to identify intravascular air before embolization to the pulmonary vasculature. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Bedside ultrasound can be used as a tool for early diagnosis of intravascular air. Emergency physicians should be aware of the typical sonographic manifestations of intravascular air and the initial steps in treating vascular air embolism.

Neurosurgical procedures in the semisitting position: evaluation of the risk of paradoxical venous air embolism in patients with a patent foramen ovale

OBJECTIVE

To analyze the actual risk for patients with a patent foramen ovale (PFO) to experience a clinically relevant venous air embolism (VAE) during surgery performed in the semisitting position.

METHODS

All procedures were performed between January 2008 and December 2009, under general anesthesia and in the semisitting position. Transesophageal echocardiography (TEE) and capnometry were used intraoperatively to monitor for air bubbles in the venous system.

RESULTS

Of 200 consecutive patients who all were operated on in the semisitting position, 52 patients (26%) had a diagnosis of PFO. Rates of VAE in patients were graded as follows: grade 0 (no air bubbles visible, no air embolism), 23 patients (44.2%); grade I (air bubbles on TEE), 22 patients (42.3%); grade II (air bubbles on TEE with decrease of end-tidal carbon dioxide [ETCO2] ≤ 3 mm Hg), 2 patients (3.8%); grade III, air bubbles on TEE with decrease of ETCO2 >3 mm Hg, 4 patients (7.7%); grade IV, air bubbles on TEE with decrease of ETCO2 >3 mm Hg and decrease of mean arterial pressure ≥ 20% or increase of heart rate ≥ 40% (or both), 1 patient (1.9%); and grade V, VAE causing arrhythmia with hemodynamic instability requiring cardiopulmonary resuscitation, 0 patients (0%). There were no deaths in this series, and no new or unexplained, mild or severe neurologic deficits were caused by a VAE.

CONCLUSIONS

Under standardized anesthesia and neurosurgical protocols, patients with a PFO can be operated on safely in the semisitting position.

Incidence of venous air embolism during myomectomy: the effect of patient position

PURPOSE

Venous air embolism (VAE) is characterized by the entrainment of air or exogenous gases from broken venous vasculature into the central venous system. No study exists regarding the effect of patient positioning on the incidence of VAE during abdominal myomectomy. The purpose of this study was to assess the incidence and grade of VAE during abdominal myomectomy in the supine position in comparison to those in the head-up tilt position using transesophageal echocardiography.

MATERIALS AND METHODS

In this study, 84 female patients of American Society of Anesthesiologist physical status I or II who were scheduled for myomectomy under general anesthesia were included. Patients were randomly divided into two groups: supine group and head-up tilt group. Transesophageal echocardiography images were videotaped throughout the surgery. The tapes were then reviewed for VAE grading.

RESULTS

In the supine group, 10% of the patients showed no VAE. Moreover, 10% of the patients were classified as grade I VAE, while 50% were categorized as grade II, 22.5% as grade III, and 7.5% as grade IV. In the head-up tilt group, no VAE was detected in 43.2% of the patients. In addition, 18.2% of the patients were classified as grade I VAE, 31.8% as grade II, and 6.8% as grade III; no patients showed grade IV. VAE grade in the head-up tilt group was significantly lower than that in the supine group (p<0.001).

CONCLUSION

The incidence and grade of VAE in the head-up tilt group were significantly lower than those in the supine group during abdominal myomectomy.

Anesthetic Considerations in Hepatectomies under Hepatic Vascular Control

Background. Hazards of liver surgery have been attenuated by the evolution in methods of hepatic vascular control and the anesthetic management. In this paper, the anesthetic considerations during hepatic vascular occlusion techniques were reviewed. Methods. A Medline literature search using the terms "anesthetic," "anesthesia," "liver," "hepatectomy," "inflow," "outflow occlusion," "Pringle," "hemodynamic," "air embolism," "blood loss," "transfusion," "ischemia-reperfusion," "preconditioning," was performed. Results. Task-orientated anesthetic management, according to the performed method of hepatic vascular occlusion, ameliorates the surgical outcome and improves the morbidity and mortality rates, following liver surgery. Conclusions. Hepatic vascular occlusion techniques share common anesthetic considerations in terms of preoperative assessment, monitoring, induction, and maintenance of anesthesia. On the other hand, the hemodynamic management, the prevention of vascular air embolism, blood transfusion, and liver injury are plausible when the anesthetic plan is scheduled according to the method of hepatic vascular occlusion performed.

[Surgery in the sitting position : anesthesiological considerations]

Surgical interventions in the sitting position are intended to optimize surgical conditions by reducing bleeding in the operation field and improving the surgical approach. There are, however, some potentially life-threatening risks associated with surgery in the sitting position. Of these risks, air embolism is one of the most serious complications and should be detected immediately in order to initiate specific countermeasures. In addition to standard monitoring procedures, transthoracic Doppler ultrasound and transesophageal echocardiography are valuable methods used to detect the presence of air in the vasculature. If an air embolism becomes apparent, further targeted measures are needed to prevent or aggressively treat the progression of potentially life-threatening consequences.

Transnasal TOE: An alternate approach in the setting of difficult probe placement for seated spinal surgery

Transnasal transoesophageal echocardiography may be an effective alternative approach when difficulty is encountered while placing a probe for patients with severe kyphoscoliosis. We describe a successful approach in a patient presenting for orthopaedic fixation and review the current literature.

[Paradoxal gazous embolism in hepatic trauma. Contribution of hyperbaric oxygenotherapy]

A young man was admitted for a polytraumatism associating head trauma and blunt abdominal trauma with hepatic injury. He was managed with a damage control surgery with a perihepatic packing. During the second look surgery, he developed a paradoxal gazous embolism by air aspiration in the sus-hepatic vein. This has never been described before in such traumatism. The patient presented a respiratory distress, a circulatory shock due to right infarction and an intracranial hypertension with bilateral mydriasis. He was immediately treated by hyperbaric oxygenotherapy. The evolution was good and he recovered without sequelae.

Intracardiac transvenous echocardiography is superior to both precordial Doppler and transesophageal echocardiography techniques for detecting venous air embolism and catheter-guided air aspiration

BACKGROUND

Venous air embolism (VAE) is a potentially fatal complication during surgical procedures with patients in the sitting position. Since methods for detection of persistent low-volume VAE and targeted air aspiration are limited, we tested the hypotheses that transvenous intracardiac echocardiography (ICE) 1) improves detection of small air emboli in comparison to transesophageal echocardiography (TEE) and precordial Doppler monitoring (PCD) techniques, and that 2) image-guided multiorifice central venous catheter manipulation improves air recovery in moderate and large VAE, when compared with aspiration with the multiorifice central venous catheter in a static position.

METHODS AND RESULTS

Adult swine (73 +/- 4.6 kg, n = 7) were premedicated, anesthetized with propofol and fentanyl, endotracheally intubated, mechanically ventilated, and placed in a 45 degrees head-up position. First, nine different small volumes of air emboli (0.05-1 mL) were randomly injected via an ear vein, and VAE detection methods were applied in random order. For 378 small volume air injections, ICE had a much higher sensitivity (82.5%, P < 0.0001) on the analysis of VAE detection than TEE (52.8%) or PCD (46.8%), with no difference (P = 0.571) between TEE and PCD. An injected air volume as small as 0.15 mL was detected by ICE in 90% of injections performed, whereas PCD and TEE detected only half of the boluses of 0.25-0.30 mL of air, and required boluses of 0.4-1.0 mL to achieve 100% detection. Air recovery was assessed in a second series of moderate VAE (2, 5, 10 mL); image-guided aspiration-catheter manipulation recovered significantly more (34.1% vs 17.2%, P < 0.0001) intracardiac air than without catheter manipulation. In a third series of injections of large air volumes (25, 50, and 100 mL), air recovery was not significantly different with ultrasound-guided aspiration (41.3% vs 31.8%, P = 0.11).

CONCLUSION

Small air emboli are detected by ICE with much greater sensitivity compared with both PCD and TEE techniques. Furthermore, recovery of embolized air is enhanced by image-guided manipulation of a multiorifice central venous catheter. Clinical studies are required to assess this technique during surgery with patients in the sitting position.

Venous air embolism during surgery, especially cesarean delivery

Venous air embolism (VAE) is the entrapment of air or medical gases into the venous system causing symptoms and signs of pulmonary vessel obstruction. The incidence of VAE during cesarean delivery ranges from 10 to 97% depending on surgical position or diagnostic tools, with a potential for life-threatening events. We reviewed extensive literatures regarding VAE in detail and herein described VAE during surgery including cesarean delivery from background and history to treatment and prevention. It is intended that present work will improve the understanding of VAE during surgery.

Possible Air Embolism During Eye Surgery

We report a case of possible air embolism during a three-port pars plana vitrectomy and air-fluid exchange of the vitreous cavity of the eye. After the start of intraocular air flushing, sudden tachycardia, a decrease in oxygen saturation and end-tidal carbon dioxide tension, and a distinct "mill-wheel" murmur were observed. Venous air embolism was suspected but other sources of air entry into the circulation and a thromboembolic event were excluded. Once intraocular air flushing was ceased, clinical variables returned to normal within minutes. In conclusion, during air-fluid exchange of the vitreous cavity, air embolism should be considered as a possible rare complication.

Pulmonary air embolism

Pulmonary air embolism is a well-known consequence of surgery, trauma, diving, and aviation. This article reviews the physiological effects, means of detection and methods of prevention and treatment of pulmonary air embolism. The primary physiological effects are elevated pulmonary artery pressures, increased ventilation-perfusion inhomogeneity, and right ventricular failure. The degree of physiological impairment depends on the volume of gas entrained, the rate of entrainment, the type of gas entrained, and the position of the patient when the embolism occurs. Transesophageal echocardiography is the most sensitive method of detection, but it is invasive. Precordial Doppler ultrasound is almost as sensitive and poses no risk to the patient. End-tidal carbon dioxide monitoring is used on all patients and is a moderately sensitive method of detection, which is useful during surgeries that have a low incidence of air embolism. For high-risk procedures, precordial Doppler ultrasound and a multi-orifice right heart catheter should be used to detect and treat pulmonary air embolism. Prevention measures include volume expansion, careful positioning, positive end-expiratory pressure, military anti-shock trousers, and jugular venous compression. Treatment of pulmonary air embolism includes flooding the surgical site with saline, controlling sites of air entry, repositioning the patient with the surgical site below the right atrium, aspiration of air from a central venous catheter, cessation of inhaled nitrous oxide, and resuscitation with oxygen, intravenous fluids, and inotropic agents. Some hypotheses on the effects of air in the pulmonary vasculature and investigational treatment options are discussed.

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.

IMPLICATIONS

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.

Monitoring for suspected pulmonary embolism

It is fortunate that serious embolic phenomena are uncommon because, with the exception of neurosurgery in the sitting position and cardiac surgery, thoracic echocardiography and the precordial Doppler device, the most sensitive indicators of embolism, are seldom used. Vigilance is required of the anesthesiologist to recognize the rapid fall in end-tidal PCO2, the usual first indicator of a clinically significant PE. Any sudden deterioration in the patient's vital signs should include embolism in the differential diagnosis, particularly during procedures that carry a high risk of the complication.

Minimally invasive cardiac surgery for intracardiac congenital lesions

OBJECTIVE

Minimally invasive cardiac surgery has recently been applied to the correction of intracardiac lesions. This report reviews our experience of minimally invasive cardiac surgery in 119 patients with intracardiac congenital lesions.

METHODS

From October 1995 to April 1997, 119 patients (48 male and 71 female, aged 0.9-65 years old, 18.5+/-17.8) received elective minimally invasive cardiac surgery at Chang Gung Memorial Hospital, Taipei, Taiwan for repair of atrial septal defect (96 patients) or ventricular septal defect (23 patients). The operations were performed through right submammary incision (ASD) or left parasternal minithoracotomy (VSD), under femoro-femoral or femoro-atrial cardiopulmonary bypass with fibrillatory arrest.

RESULTS

All of the defects were repaired successfully. The bypass time was 25-125 min (46+/-18). The operation time was 1.5-5.2 h (2.8+/-0.8). The postoperative course was uneventful in all patients. Follow-up (1.0-18.2 months, mean 7.3) was complete, with no late deaths or residual shunt. All patients were found to be in NYHA functional class I or II.

CONCLUSION

Our experience demonstrate that minimally invasive cardiac surgery is a technically feasible, safe, and effective procedure in surgical correction of selective simple intracardiac congenital lesions, yielding good short-term results.