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Background: Very few studies have examined the association between contrast-enhanced computed tomography (CT) findings observed in portal venous gas (PVG) and pneumatosis intestinalis (PI) and the underlying diseases in these conditions., Objectives: In this study, we analyzed this association and report the findings for predicting mortality., Materials and Methods: Overall, 50 patients diagnosed with PVG or PI, observed on contrast-enhanced CT, underwent treatment at our hospital. Based on the underlying disease, we divided the patients into three groups, those with ischemic disease, infectious disease, or gastrointestinal dilatation. Furthermore, cases that underwent surgical treatment or needed surgery but were inoperable were assigned to the high risk group (n=16) and patients who received conservative treatment were assigned to the low risk group (n=34). We reviewed the patients' medical charts, laboratory data, and CT images retrospectively, and analyzed the relationship between CT findings, underlying disease, and association with the high risk or low risk group in each case., Results: Poor enhancement of the intestinal wall, mesenteric fat stranding, extrahepatic PVG, advanced age, and renal disease were significantly associated with ischemic disease (p=0.02, p=0.02, p=0.005, p=0.008 and p=0.049, respectively). PI alone was strongly associated with gastrointestinal dilatation (p=0.009). Patients in the low risk group had more favorable outcomes with conservative treatment. In multivariate analysis, extrahepatic PVG was the only factor associated with the high risk group (p=0.002)., Conclusion: Extrahepatic PVG associated with ischemic disease was the strongest predictive factor of mortality. Other CT findings, though useful in diagnosing the underlying disease, were not significant predictive factors.

Sea turtles that are entrapped in static and towed nets may develop gas embolism which can lead to severe organ injury and death. Trawling characteristics, physical and physiologic factors associated with gas-embolism and predictors of mortality were analysed from 482 bycaught loggerheads. We found 204 turtles affected by gas-embolism and significant positive correlations between the presence of gas-embolism and duration, depth, ascent rate of trawl, turtle size and temperature, and between mortality and ascent time, neurological deficits, significant acidosis and involvement of > 12 cardiovascular sites and the left atrium and sinus venosus-right atrium. About 90% turtles with GE alive upon arrival at Sea Turtle Clinic recovered from the disease without any supportive drug therapy. Results of this study may be useful in clinical evaluation, prognostication, and management for turtles affected by gas-embolism, but bycatch reduction must become a priority for major international organizations. According to the results of the present study the measures to be considered to reduce the catches or mortality of sea turtles for trawling are to be found in the modification of fishing nets or fishing operations and in greater awareness and education of fishermen., (© 2021. The Author(s).)

Background: Surveillance of maternal mortality and severe maternal morbidity is important to identify temporal trends, evaluate the impact of clinical practice changes or interventions, and monitor quality of care. A common source for severe maternal morbidity surveillance is hospital discharge data. On October 1, 2015, all hospitals in the United States transitioned from the International Classification of Diseases, Ninth Revision, Clinical Modification to the International Classification of Diseases, Tenth Revision, Clinical Modification coding for diagnoses and procedures., Objective: This study aimed to evaluate the impact of the transition from the International Classification of Diseases, Ninth Revision, Clinical Modification to the International Classification of Diseases, Tenth Revision, Clinical Modification coding systems on the incidence of severe maternal morbidity in the United States in hospital discharge data., Study Design: Using data from the National Inpatient Sample, obstetrical deliveries between January 1, 2012, and December 31, 2017, were identified using a validated case definition. Severe maternal morbidity was defined using the International Classification of Diseases, Ninth Revision, Clinical Modification (January 1, 2012, to September 30, 2015) and the International Classification of Diseases, Tenth Revision, Clinical Modification (October 1, 2015, to December 31, 2017) codes provided by the Centers for Disease Control and Prevention. An interrupted time series and segmented regression analysis was used to assess the impact of the transition from the International Classification of Diseases, Ninth Revision, Clinical Modification to the International Classification of Diseases, Tenth Revision, Clinical Modification coding on the incidence of severe maternal morbidity per 1000 obstetrical deliveries., Results: From 22,751,941 deliveries, the incidence of severe maternal morbidity in the International Classification of Diseases, Ninth Revision, Clinical Modification coding era was 19.04 per 1000 obstetrical deliveries and decreased to 17.39 per 1000 obstetrical deliveries in the International Classification of Diseases, Tenth Revision, Clinical Modification coding era (P<.001). The transition to International Classification of Diseases, Tenth Revision, Clinical Modification coding led to an immediate decrease in the incidence of severe maternal morbidity (-2.26 cases of 1000 obstetrical deliveries) (P<.001). When blood products transfusion was removed from the case definition, the magnitude of the decrease in the incidence of SMM was much smaller (-0.60 cases/1000 obstetric deliveries), but still significant (P<.001)., Conclusion: After the transition to the International Classification of Diseases, Tenth Revision, Clinical Modification coding for health diagnoses and procedures in the United States, there was an abrupt statistically significant and clinically meaningful decrease in the incidence of severe maternal morbidity in hospital discharge data. Changes in the underlying health of the obstetrical population are unlikely to explain the sudden change in severe maternal morbidity. Although much work has been done to validate the International Classification of Diseases, Ninth Revision, Clinical Modification codes for severe maternal morbidity, it is critical that validation studies be undertaken to validate the International Classification of Diseases, Tenth Revision, Clinical Modification codes for severe maternal morbidity to permit ongoing surveillance, quality improvement, and research activities that rely on hospital discharge data., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Hepatic portal venous gas (HPVG) generally indicates poor prognoses in patients with serious intestinal damage. Although surgical removal of the damaged portion is effective, some patients can recover with conservative treatments., Aim: To establish an optimal treatment strategy for HPVG, we attempted to generate computed tomography (CT)-based criteria for determining surgical indication, and explored reliable prognostic factors in non-surgical cases., Methods: Thirty-four cases of HPVG (patients aged 34-99 years) were included. Necessity for surgery had been determined mainly by CT findings ( i.e . free-air, embolism, lack of contrast enhancement of the intestinal wall, and intestinal pneumatosis). The clinical data, including treatment outcomes, were analyzed separately for the surgical cases and non-surgical cases., Results: Laparotomy was performed in eight cases (surgical cases). Seven patients (87.5%) survived but one (12.5%) died. In each case, severe intestinal damage was confirmed during surgery, and the necrotic portion, if present, was removed. Non-occlusive mesenteric ischemia was the most common cause ( n = 4). Twenty-six cases were treated conservatively (non-surgical cases). Surgical treatments had been required for twelve but were abandoned because of the patients' poor general conditions. Surprisingly, however, three (25%) of the twelve inoperable patients survived. The remaining 14 of the 26 cases were diagnosed originally as being sufficiently cured by conservative treatments, and only one patient (7%) died. Comparative analyses of the fatal ( n = 10) and recovery ( n = 16) cases revealed that ascites, peritoneal irritation signs, and shock were significantly more frequent in the fatal cases. The mortality was 90% if two or all of these three clinical findings were detected., Conclusion: HPVG related to intestinal necrosis requires surgery, and our CT-based criteria are probably useful to determine the surgical indication. In non-surgical cases, ascites, peritoneal irritation signs and shock were closely associated with poor prognoses, and are applicable as predictors of patients' prognoses., (©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.)

To describe the technical characteristics of fatal diving mishaps and to elucidate the causes of death using a sequence analysis and a multidisciplinary investigation of diving-related fatalities. All cases of diving deaths recorded on the coast of Girona (Spain) between January 2009 and May 2018 were analyzed. Most data were obtained from the police technical reports and the forensic pathology service. Each accident was analyzed in order to identify the trigger, disabling agent, disabling injury, and cause of death. During the study period 25 diving-related fatalities were recorded. Most of the victims were males aged 50-69 years, and 11 were experienced divers. Almost all victims were using open-circuit SCUBA to breathe with compressed air as their sole gas supply. None of the victims were diving alone. The most common identified triggers included exertion, panic, buoyancy problems, disorientation and confusion. The main factors identified as disabling agents were rapid ascent, a cardiac incident, panic and entrapment. Asphyxia, lung over expansion, and myocardial ischemia were the most frequent disabling injuries. Finally, drowning represented the main cause of death, followed by arterial gas embolism and natural causes or internal diseases. A differential diagnosis, performed in the setting of a multidisciplinary investigation, is essential for elucidating the cause of death in diving-related fatalities. The proposed sequence analysis allows to clarify underlying problems in these cases and to identify risk factors and unsafe behaviors in diving.

Gas does not occur naturally in the cardiovascular system, although it is not unusual to identify it on imaging. The true incidence is difficult to know as asymptomatic cases are rarely recorded. In iatrogenic instance, this occurs when atmospheric air enters the cardiovascular system from a high to low pressure, or when gas is forcibly injected into a vessel. The source of air must be promptly identified and treatment must be expedited to reduce morbidity and mortality. This pictorial review aims to give an overview of the causes (with particular emphasis on the conditions that may be encountered by a Radiologist), appearances of cardiovascular gas, and any subsequent treatment.

Background: Hepatic portal venous gas (HPVG) is rare but potentially serious condition. Main cause of HPVG is bowel ischemia, while detection of HPVG without bowel ischemia may have been increasing possibly due to widespread use of computed tomography. However, little is known about variation in etiologies of HPVG and mortality of HPVG with each etiology. We examined patient backgrounds, underlying diseases, and in-hospital mortality of HPVG patients using a national inpatient database., Methods: Using the Diagnosis Procedure Combination database in Japan, we identified inpatients diagnosed with HPVG from July 1, 2010 to March 31, 2015. Patients' data included age, sex, comorbidities at admission, complications after admission, body mass index, surgical procedures, medications, and discharge status. In-hospital mortality was compared between the subgroups divided by the patient backgrounds and underlying diseases., Results: A total of 1590 patients were identified during the study period. The mean age was 79.3 years old and the proportion of bowel ischemia was 53%. The overall in-hospital mortality was 27.3%. In-hospital mortality of HPVG with bowel ischemia, gastrointestinal tract (GIT) obstruction or dilation, GIT perforation, GIT infection, or sepsis was 26.8, 31.1, 33.3, 13.6, or 56.4%, respectively. Among patients with bowel ischemia, 32.2% patients received operation and their in-hospital mortality was 16.5%., Conclusions: HPVG patients in the present study were relatively older but less likely to die than those in previous studies. Attention should be paid to the fact that mortality of HPVG without bowel ischemia was not always lower compared to that with bowel ischemia.

Background: Venous air embolism is a potentially life-threatening complication of IV catheter use in horses. Despite widespread anecdotal reports of their occurrence, few cases have been reported in the literature and the prognosis is currently unknown., Hypothesis/objectives: Our objective was to describe the surrounding circumstances, clinical signs, treatment, progression, and outcome of venous air embolism in hospitalized horses., Animals: Thirty-two horses with acute onset of compatible clinical signs associated with IV catheter disconnection or damage., Methods: Multicenter retrospective study. Data extracted from clinical records included signalment, presenting complaint, catheter details, clinical signs, treatments, and outcome., Results: Most cases resulted from extension set disconnection occurring within approximately 24 hours after catheter placement. In fewer horses, extension set damage was cited as a cause. Common clinical signs included tachycardia, tachypnea, recumbency, muscle fasciculations and agitation, with abnormal behavior including kicking and flank biting. Less commonly, pathological arrhythmias or more severe neurologic signs, including blindness and seizures, were noted. Progression was unpredictable, with some affected horses developing delayed-onset neurologic signs. Mortality was 6/32 (19%), including 2 cases of sudden death and other horses euthanized because of persistent neurologic deficits. Negative outcomes were more common in horses with recorded blindness, sweating or recumbency, but blindness resolved in 5/8 affected horses., Conclusions and Clinical Importance: The prognosis for resolution of clinical signs after air embolism is fair, but permanent neurologic deficits or pathologic cardiac arrhythmias can arise. Unpredictable progression warrants close monitoring. Systematic clinic-based surveillance could provide additional useful information to aid prevention., (Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Introduction: Systemic air embolism (SAE) is a rare but serious complication following endoscopic procedures. It may occur with or without direct vessel injury. The aim of this work is to review cases of SAE following endoscopy without proven vessel injury., Methods: In this systematic review PubMed database was screened for SAE following endoscopy from 1990 to 2015. Only cases without proven major vessel injury were included in the analysis. Including one case of SAE after colonoscopy from our hospital the analysis comprised 40 cases., Results: 60% of patients underwent ERCP, 33% gastroscopy and the remaining 7% other endoscopic procedures. Among patients suffering from SAE the majority had cerebral embolism (73%). In 46% of documented echocardiography a patent foramen ovale (PFO) has been confirmed as mechanism of paradoxical air embolism. Therapeutic approaches comprised most frequently hyperbaric oxygenation. In 35% of cases advanced life support was necessary whereas only 55% of patients survived SAE in total., Conclusion: SAE is a serious complication of endoscopic procedures with high morbidity and mortality. In patients with present PFO high awareness should be paid to informed consent for the risk of SAE, especially stroke. Cautiousness with sedation is necessary in those patients not to delay clinical recognition of neurological SAE symptoms., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: Systemic air embolism (AE) is a rare but feared complication of transthoracic biopsy with potentially fatal consequences. The aim of the study was to assess the effect of patient positioning during transthoracic biopsy on preventing systemic AE., Materials and Methods: We compared a historical control group of 610 patients (group 1) who underwent transthoracic biopsy before the implementation of measures to prevent systemic AE during transthoracic biopsy and a group of 1268 patients (group 2) who underwent biopsy after the measures were implemented. The patients in group 2 were placed in the ipsilateral-dependent position so that the lesion being biopsied was located below the level of the left atrium., Results: The rate of systemic AE was reduced from 3.77% to 0.16% (odds ratio [OR], 0.040; 95% CI, 0.010-0.177; p < 0.001). Logistic regression analyses identified needle penetration depth, prone position of the patient during biopsy, location above the level of the left atrium, needle path through ventilated lung, and intubation anesthesia as independent risk factors for systemic AE (p < 0.05). Propensity score-matched analyses identified the number of biopsy samples obtained as an additional risk factor (p = 0.003). The rate of pneumothorax was reduced from 15.41% in group 1 to 5.99% in group 2 (OR, 0.374; 95% CI, 0.307-0.546; p < 0.001)., Conclusion: Performing transthoracic biopsy with the patient in an ipsilateral-dependent position so that the lesion is located below the level of the left atrium is an effective measure for preventing systemic AE. Needle path through ventilated lung and intubation anesthesia should be avoided whenever possible.

Patients on chronic hemodialysis have a shortened survival compared to the general population. There are multiple sources of morbidity and mortality unique to the dialysis population that account for this. Reasons include the effects of blood membrane interactions, intradialytic hypotension, myocardial stunning, excessive interdialytic weight gain, high-flow arteriovenous fistulae, and impaired lipid break down by anticoagulation administered during HD. Another risk factor, not well appreciated, is the occurrence of microemboli of air (microbubbles) during HD. Such microemboli are not effectively removed by the venous air trap and the safety system provides no warning when these small microbubbles enter the venous bloodline of the extra corporeal circuit and then the venous circulation of the patient. Data indicate that the gas emboli are not fully adsorbed and become embedded by fibrin resulting in a combined clot that causes microemboli in the lung. In addition, these microbubbles (of the size of blood corpuscles) can pass the pulmonary circulation into the left heart and then into the general arterial circulation explaining their detection not only in the lungs but also in the brain and heart of patients. Risk factors for such microbubble appearance include the high blood pump speed associated with high-efficiency dialyses. This review will discuss these various issues in relation to the better outcome of patients in Japan and also how to reduce some of these risk factors., (© 2016 Wiley Periodicals, Inc.)

Introduction: The aim of this study was to review patients with iatrogenic cerebral gas embolism (CGE) referred to The Alfred Hospital hyperbaric unit to determine whether hyperbaric oxygen treatment (HBOT) reduced morbidity and mortality., Methods: This is a retrospective cohort study with a contemporaneous comparison group of patients referred between January 1998 and December 2014. The primary end point was good neurological outcome at the time of discharge from hospital or rehabilitation facility as assessed by the Glasgow Outcome Scale (GOS-E)., Results: Thirty-six patients were treated with HBOT for CGE and nine patients were diagnosed with CGE but did not receive HBOT. Thirty-two patients developed CGE from an arterial source and 13 from a venous source. The mean time from recognition of the event to institution of HBOT was 15 hours. Four of 45 patients (8.9%) died. Good neurological outcomes (defined as GOS-E 7 or 8) occurred in 27 patients and moderate disability in 13. The only independent factor that was associated with good neurological outcome was time to first HBOT (OR 0.94, 0.89-0.99; P = 0.05). Hemiplegia as the first presenting sign, however, was associated with poor outcome (OR 0.27, 0.06-1.08; P = 0.05). The source of embolus (arterial versus venous), hyperbaric treatment table used and patient age did not affect outcome., Conclusion: Appropriate treatment of CGE with hyperbaric oxygen was found to be impeded by delays in diagnosis and subsequent transfer of patients. Better neurological outcome was associated with HBOT within eight hours of CGE.

Air embolism during endoscopic retrograde cholangiopancreatography is a rare but potentially fatal complication. A 66-year-old man underwent endoscopic retrograde cholangiopancreatography and remained stable until the end of the procedure, when he was found to have mottling on his right side and became hypoxic and unresponsive. Transesophageal echocardiography showed air within the left ventricle, consistent with systemic air embolism. Mortality resulted from significant cardiac and cerebral ischemia. The literature suggests that capnography is helpful in early diagnosis of air embolus, but it could not be used in this case because the patient's trachea was not intubated.

Objective: This study aims to evaluate the performance of Simplified Acute Physiology Score II (SAPS II), the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and the Sequential Organ Failure Assessment (SOFA) score for predicting illness severity and the mortality of adult hepatic portal venous gas (HPVG) patients presenting to the emergency department (ED). This will assist emergency physicians in risk stratification., Methods: Data for 48 adult HPVG patients who visited our ED between December 2009 and December 2013 were analyzed. The SAPS II, APACHE II score, and SOFA score were calculated based on the worst laboratory values in the ED. The probability of death was calculated for each patient based on these scores. The ability of the SAPS II, APACHE II score, and SOFA score to predict group mortality was assessed by using receiver operating characteristic curve analysis and calibration analysis., Results: The sensitivity, specificity, and accuracy were 92.6%,71.4%, and 83.3%, respectively, for the SAPS II method; 77.8%, 81%, and 79.2%, respectively, for the APACHE II scoring system, and 77.8%, 76.2%, and 79.2%, respectively, for the SOFA score. In the receiver operating characteristic curve analysis, the areas under the curve for the SAPS II, APACHE II scoring system, and SOFA score were 0.910, 0.878, and 0.809, respectively., Conclusion: This is one of the largest series performed in a population of adult HPVG patients in the ED. The results from the present study showed that SAPS II is easier and more quickly calculated than the APACHE II and more superior in predicting the mortality of ED adult HPVG patients than the SOFA. We recommend that the SAPS II be used for outcome prediction and risk stratification in adult HPVG patients in the ED., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Death as a result of air embolism has been reported following sexual activity such as vaginal insufflation or coitus a tergo. It is a very uncommon cause of death, however, during pregnancy and puerperium the risk increases due to non-collapsible veins at the placental site. Air embolism should be suspected in all sudden female deaths related to sexual activity in order to initiate appropriate treatment to minimize maternal and fetal morbidity and mortality.

Background: Iatrogenic cerebral arterial gas embolism (CAGE) is an uncommon but potentially a fatal condition. Hyperbaric oxygen (HBO2) therapy is the only definitive treatment for patients with CAGE presenting with acute neurologic deficits., Methods: We reviewed medical records and neuroimaging of consecutive CAGE patients treated with HBO2 at a state referral hyperbaric facility over a 22-year period. We analyzed the effect of demographics, source of intra-arterial gas, signs and symptoms, results of imaging studies, time between event and HBO2 treatment, and response to HBO2 treatment in 36 consecutive patients. Favorable outcome was defined by complete resolution or improvement of CAGE signs and symptoms at 24 h after HBO2 treatment. Unfavorable outcome was defined by unchanged or worsened neurologic signs and symptoms or in hospital death., Results: A total of 26 (72%) of the 36 patients had favorable outcome. Patients with favorable outcome were younger compared to those with unfavorable outcome (mean age [years, SD] 44.7 ± 17.8 vs. 58.1 ± 24.1, p = 0.08). Cardiopulmonary symptoms were significantly more common in CAGE related to venous source of gas compared to arterial source (p = 0.024) but did not influence the rate of favorable outcomes. Adjusted multivariate analysis demonstrated that time from event to HBO2 ≤ 6 h (positively) and the presence of infarct/edema on head computerized tomography (CT)/magnetic resonance imaging (MRI) before HBO2 (negatively) were independent predictors of favorable outcome at 24 h after HBO2 treatment [odds ratio (OR) 9.08 confidence interval (CI) (1.13-72.69), p = 0.0376, and (OR) 0.034 (CI) (0.002-0.58), p = 0.0200, respectively]. Two of the 36 patients were treated with thrombolytics because of acute focal deficits and suspected ischemia-one with intravenous and the second with intra-arterial thrombolysis. The latter patient developed fatal intracerebral hemorrhage., Conclusions: A high proportion of CAGE patients treated with HBO2 had favorable outcomes. Time-to-HBO2 ≤ 6 h increased the odds of favorable outcome, whereas the presence of infarct/edema on CT/MRI scan before HBO2 reduced the odds of a favorable outcome. Timely diagnosis and differentiation from thrombo-embolic ischemic events appears to be an important determinant of successful HBO2 treatment.

In order to investigate causative factors, root cause analysis (RCA) was applied to 351 Australian compressed-gas diving fatalities from 1972-2005. Each case was described by four sequential events (trigger, disabling agent, disabling injury, cause of death) that were assessed for frequency, trends, and dive and diver characteristics. The average age increased by 16 years, with women three years younger than men annually. For the entire 34-year period, the principal disabling injuries were asphyxia (49%), cerebral arterial gas embolism (CAGE; 25%), and cardiac (19%). There was evidence of a long-term decline in the rate of asphyxia and a long-term increase in CAGE and cardiac disabling injuries. Asphyxia was associated with rough water, buoyancy trouble, equipment trouble, and gas supply trouble. CAGE was associated with gas supply trouble and ascent trouble, while cardiac cases were associated with exertion, cardiovascular disease, and greater age. Exertion was more common in younger cardiac deaths than in older deaths. Asphyxia became less common with increasing age. Equipment-related problems were most common during the late 1980s and less so in 2005. Buoyancy-related deaths usually involved loss of buoyancy on the surface but decreased when buoyancy control devices were used. Countermeasures to reduce fatalities based on these observations will require validation by active surveillance.

Background and Purpose: Cerebral microembolic signals detected by transcranial Doppler are frequent during carotid angioplasty with stenting and carotid endarterectomy (CEA). Their potential harmful effects on the brain are, however, unclear. The aim of this study was to relate the frequency and type of per-procedural microembolic signals to procedure-related ipsilateral ischemic strokes and new ipsilateral ischemic lesions on diffusion-weighted cerebral MRI., Methods: Eighty-five patients who were prospectively treated with CEA (61) or carotid angioplasty with stenting (30) for high-grade (>/=70%) internal carotid artery stenoses were monitored during the procedures using multifrequency transcranial Doppler with embolus detection and differentiation. Pre- and postprocedural cerebral diffusion-weighted cerebral MRIs were performed on a subset of patients., Results: Solid and gaseous microemboli were independently associated with procedure-related ipsilateral ischemic strokes (solid: P=0.027, gaseous: P=0.037) or new ipsilateral diffusion-weighted cerebral MRI lesions (solid: P=0.043, gaseous: P=0.026). Microembolic signals were detected during all procedures except one (CEA); 17% and 21% of all emboli were solid during carotid angioplasty with stenting and CEA, respectively. Patients undergoing carotid angioplasty with stenting had more solid (P<0.001) and gaseous (P<0.001) emboli and more new ipsilateral ischemic strokes (P=0.033) compared with patients undergoing CEA. Echolucent plaques (P=0.020) and preprocedural diffusion-weighted cerebral MRI ischemic lesions (P=0.002) were associated with increased numbers of solid emboli., Conclusions: Solid and gaseous microemboli were increased in patients with procedure-related ipsilateral ischemic strokes or new diffusion-weighted cerebral MRI lesions, which suggests that both solid and gaseous emboli may be harmful to the brain during CEA and carotid angioplasty with stenting.

A fatal pulmonary air embolism, confirmed by an oriented necropsy, is described in a 25-day-old premature and small-for-gestational-age neonate. The embolism was suspected after air bubbles were detected in the infusion line. The air bubbles originated from a male Luer-lock to male Luer-lock connector, which was part of a specific assembly of the perfusion line. A solution to this problem is thereby proposed. We recommend caution in using complex infusion line assemblies because such complications are probably underestimated.

Objective: Cerebral microembolization is a well-recognized phenomenon after cardiac valve replacement, but the relative proportion of solid and gaseous emboli is uncertain. Particulate microemboli are thought to be the most damaging. With the use of multifrequency transcranial Doppler ultrasound, we compared the number and nature of microemboli in recipients of biologic and mechanical aortic valve prostheses., Methods: The middle cerebral arteries of 60 patients were monitored bilaterally with a new-generation transcranial Doppler ultrasound (Embo-Dop, DWL Elektronische Systeme GmbH, Singen, Germany) that rejects artefacts online and automatically discriminates between solid and gaseous microemboli. All recordings were performed during a 30-minute period 1 day before and at a mean of 5 days and 3 months after isolated aortic valve replacement with a biologic (30, group B) or mechanical (30, group M) prosthesis., Results: The patients in group B were older, with a mean age of 70.6 +/- 9.7 years versus 55.4 +/- 9.4 years (P < .005) in the patients in group M. Biologic prosthesis recipients were all taking aspirin (no warfarin); patients with mechanical valves were well anticoagulated with warfarin both 5 days and 3 months after surgery. None of the patients had solid microemboli preoperatively. Five days postoperatively, the absolute number of cerebral microemboli was 145 and 594 for total microemboli (P = .001) and 41 and 182 for solid microemboli (P = .002) in groups B and M, respectively. At 3 months, the absolute number was 65 and 608 for total microemboli (P < .001) and 10 and 188 for solid microemboli (P < .001) in groups B and M, respectively. Solid microemboli accounted for 16% of the total microembolic load in group B compared with 31% in group M (P = .05) at 3 months., Conclusions: Solid cerebral microemboli represent approximately one third of the total cerebral microembolic load after mechanical aortic valve replacement and are detectable in the majority of such patients both 5 days and 3 months after surgery. The neurofunctional consequences of this phenomenon should be carefully assessed.

Venous air embolism is the entry of air into the venous system as a consequence of trauma or iatrogenic complications (especially central venous cannulation or pressurized intravenous infusion systems). It also can occur following the surgical procedures. Venous air embolism results in right ventricular dysfunction and pulmonary injury. In this review article various causes, frequency, pathophysiology, clinical features, diagnosis, treatment, outcome and prevention of venous air embolism are discussed.

Background: Gas in the mesenteric or portal veins (PVG) is an uncommon entity. It was first described only in patients with mesenteric ischemia and bowel gangrene. Later, several reports described other causes for PVG in which conservative treatment was successful. In the past, the diagnosis was made by vague signs in abdominal plain films. Since the era of computerized tomography (CT) scan the diagnosis became more objective, but nevertheless it is still an elusive entity. Our objective was to relate clinical and CT findings with outcome of patients with PVG, and to determine the indications for surgical treatment., Methods: Six-year records of patients from one general hospital with CT scan findings of gas in the mesenteric or portal veins were retrospectively studied, together with details of the clinical presentation, hospital course and outcome., Results: Between 1995 and 2000, 12 patients with findings of mesenteric and portal vein gas were identified. In 7 of 12 patients (58%) PVG developed secondary to ischemia of the small or large bowel, with mortality of 86%. Metabolic acidosis was the prominent laboratory finding. Pneumatosis intestinalis was present in all of these patients. Two patients with PVG had inflammatory bowel disease and both recovered with conservative management. Another 2 patients who were treated conservatively died. One patient had severe pancreatitis and died 2 weeks after PVG was diagnosed, from septic complications, while the other patient admitted with septic shock, died of multiorgan failure. In the last patient, PVG was diagnosed in a CT scan performed to investigate fever of unknown origin. She survived with no specific treatment., Conclusion: We suggest that patients in whom PVG is found by CT scan should be treated according to their clinical status, and underlying disease. Patients suspected of having an ischemic mesenteric event should be immediately explored., (Copyright 2003 S. Karger AG, Basel)

Background: Open heart surgery is associated with a significant risk of cerebral and myocardial dysfunction, which is attributed in part to air embolism from incompletely deaired cardiac chambers. To evaluate the impact of carbon dioxide (CO2) insufflation to the thoracic cavity, a prospective randomized study was designed., Methods: A total of 62 elective patients were randomly assigned to CO2 insufflation (group I, n = 31) or control (group II, n = 31). According to the Parsonnet risk score, 16 patients in group I (52%) and 10 patients in group II (32%) were categorized as being at either high risk or extremely high risk., Results: In group II, perioperative mortality was 16.1% (5 patients); in group I, 1 patient died (ns). Creatine kinase MB isoenzyme, as a marker of myocardial damage, was more elevated in group I after surgery (38.0 +/- 4.1 vs 28.0 +/- 2.1, p = 0.02). Neurocognitive test scores did not reveal significant postoperative differences between groups., Conclusions: Although mortality was lower with CO2 insufflation, no benefit could be demonstrated for markers of cardiac ischemic damage or neurocognitive outcome in this high-risk population. As CO2 concentrations in the thoracic cavity did not necessarily reach anticipated levels, our method of application is in question.

Background/purpose: The prognostic importance of portal vein air (PVA) in babies with necrotizing enterocolitis (NEC) has been controversial. This study compares the outcome in babies with NEC and PVA treated surgically versus those with medical management., Methods: Forty neonates in the neonatal intensive care unit (NICU; 1995 through 1999) had (PVA) during their hospitalization. Babies were analyzed for gestational age (GA), birth weight (BW), and survival after operative versus medical management., Results: The average GA was 26 weeks, average BW was 1,173 g. Twenty-three patients (57.5%) tolerated full feedings and 8 (20%) partial feedings at diagnosis. All 40 babies required intubation at birth with 23 (57.5%) requiring reintubation with onset of PVA. In all cases, PVA was present within 24 hours of onset of abdominal distension, feeding intolerance, or heme-positive stools. Two cases of PVA "resolved" only to recur later in the patients' courses. Thirty-two patients (80%) manifested pneumatosis intestinalis on abdominal radiographs, and 8 (20%) had perforations. Acidosis was present in 25 (63%) patients, and vasopressor support (dopamine) was required in 15 (38%), with 2 patients requiring support only preoperatively. Initial management consisted of bowel rest, fluid resuscitation, orogastric decompression, and broad-spectrum antibiotics. Operation was performed in 31 (78%). Seventeen underwent resection with ostomy formation with 6 deaths and 11 survivors. Four underwent resection using the clip and drop back method, with one death and 3 requiring an ostomy at second look laparotomy. Ten had NEC totalis and closure of the abdomen only. Overall operative mortality rate was 17 of 31 (54%). Nine seemingly stable patients were treated nonoperatively. Six had progressed disease and died before salvage laparotomy could be performed, whereas 3 (33%) survived without further therapy., Conclusions: PVA has been a relative indication for operation. This view has been challenged by the survival of some patients without laparotomy. Although nonoperative therapy seems appealing in hemodynamically stable patients without acidosis, our data confirm the poor prognosis of infants with PVA and NEC., (Copyright 2001 by W.B. Saunders Company.)

Holter monitoring during cementation of a hip prosthesis showed sudden R-wave loss. At post mortem, demonstration of a large intracardiac air embolus may explain the ECG changes.

Background and Purpose: Whilst carbon dioxide is the gas generally used for insufflation during laparoscopy, several studies have reported adverse effects specifically associated with its use. These effects may be attributable to chemical, metabolic, or immunologic effects specific to CO2. Because helium is chemically, physiologically, and pharmacologically inert, it has been suggested as a possible substitute insufflation gas. However, there has been concern about the potential implications of venous gas embolism during helium insufflation. The aim of this study was to examine the physiological effect of the intravenous injection of He and CO2 in an experimental model., Materials and Methods: Eleven domestic white pigs were randomly allocated to receive multiple intravenous injections of increasing volumes of either CO2 or He gas. Cardiorespiratory function was measured, and the intravenous volumes of gas that resulted in cardiac arrest were determined., Result: Cardiorespiratory functional measures returned to normal quicker after CO2 than after He injection. Helium injection quickly overwhelmed the animal's ability to compensate and resulted in death at a lower volume than did CO2 injection., Conclusions: Gas embolism during He insufflation is more likely to be lethal than is CO2 embolism. This scenario is most likely following Veress needle insertion into a large vein. Therefore, if He is to be used for insufflation during clinical laparoscopy, the possibility of venous injection should be minimized by avoiding Veress needle use. Further investigation of the safety of He insufflation is warranted before a role during clinical laparoscopy can be recommended.

Unlabelled: OBJECTIVE, PATIENTS, AND METHODS: A severe case of cerebral air embolism after unintentional central venous catheter disconnection was the impetus for a systematic literature review (1975-1998) of the clinical features of 26 patients (including our patient) with cerebral air embolism resulting from central venous catheter complications., Results: The jugular vein had been punctured in eight patients and the subclavian vein, in 12 patients. Embolism occurred in four patients during insertion, in 14 patients during unintentional disconnection, and in eight patients after removal and other procedures. The total mortality rate was 23%. Two types of neurologic manifestations may be distinguished: group A (n = 14) presented with encephalopathic features leading to a high mortality rate (36%); and group B (n = 12) presented with focal cerebral lesions resulting in hemiparesis or hemianopia affecting mostly the right hemisphere, with a mortality rate as high as 8%. In 75% of patients, an early computed tomography indicated air bubbles, proving cerebral air embolism. Hyperbaric oxygen therapy was performed in only three patients (12%). A cardiac defect, such as a patent foramen ovale was considered the route of right to left shunting in 6 of 15 patients (40%). More often, a pulmonary shunt was assumed (9 of 15 patients; 60%). For the remainder, data were not available., Conclusion: When caring for critically ill patients needing central venous catheterization, nursing staff and physicians should be aware of this potentially lethal complication.

Gas bubble disease (GBD), a non-infectious, environmentally/physically induced trauma, is caused by an increase in the dissolved gas pressure above the ambient air pressure (supersaturation). Frequently the cause is an increased partial pressure of nitrogen-especially in spring-/groundwater. All fish species as well as amphibians and aquatic invertebrates are susceptible. Fish species and age groups are different sensitive; swim up fry is very endangered. The disease may occur in a chronic form at approximately 103% and in an acute form at above 110/115% total gas pressure (TGP). Fish, especially fry, with the chronic form die slowly without symptoms. The clinical symptoms of the acute form are disorientation, subcutaneous emphysema, embolism, exophthalmus mostly only on one side, swimming near the water surface with darkened skin, haemorrhages and high mortality. Losses increase with increased TGP. Generally, mortality in the chronic form increases by secondary infections of emphysematous tissue. As technical processes may be the cause for an increased total gas pressure, such as water pumping, heating water or mixing cold with warm water, in this context we could speak from a "technopathy". The following "therapeutic" measurement is recommended: avoid causal factors, transfer damaged fish in expanded water, turn off the cause, compensate the pressure in deeper water, if possible.

Centrifugal pumps will not pass gross quantities of gaseous emboli due to the nonocclusive nature of the pump. However, retrograde flow can occur under circumstances that include: product malfunctions, low flows, and human errors. Negative pressure created by falling arterial perfusate can draw air into the cannula. Food and Drug Administration (FDA) records about centrifugal pump malfunctions were obtained. Out of 350,000 cases completed with centrifugal pumps over a 23 month period, the FDA received reports of 68 malfunctions, 22 electrical burning smells, and three speed surges, yielding a failure rate of 1 in 3,763 cases. FDA records revealed five death reports and three serious injury reports. A survey was sent to 2,424 Society of Thoracic Surgeons' members to obtain more information; 285 who use centrifugal pumps responded. Sixty surgeons (21%) reported 108 malfunctions, including 46 complete pump failures. Fifty-one of 243 surgeons (21%) who use centrifugal pumps for bypass reported that perfusionists have forgotten to clamp the pump line, resulting in backflow. We conclude centrifugal pumps are generally safe, but malfunctions, low flows, and human errors can lead to retrograde flow and occasionally air embolization. There are valves that can be added to the bypass circuitry to prevent this risk.

Objective: To alert gynecologic surgeons to the risk of room air embolism during endoscopy., Design: Case reports., Setting: Medico-legal consultations., Patients: Five women having endoscopic procedures., Interventions: Endoscopy followed by emergency resuscitative measures., Results: Morbidity and mortality., Conclusions: The risk of room air embolism may be lessened by attention to the operative technique and by monitoring the end tidal carbon dioxide levels.

The use of laparoscopic surgery has grown considerably, and the occurrence of some accidents, albeit rare, is now reported. Among them, gas embolism can induce a bad postoperative outcome. We report seven cases of carbon dioxide embolism (CO2) during laparoscopic surgery. In the seven cases gas embolism occurred during insufflation or a few minutes later. All the patients had a previous abdominal or pelvic surgical history. Five patients presented cardiac bradycardia or arrhythmia. Cardiovascular collapse or cyanosis was the first manifestation in three cases. Sudden bilateral mydriasis was the earliest neurologic sign, present in five cases. Finally, the gas embolism complication was lethal in two cases. In summary, this study strongly stresses the need for precise rules of prevention of gas embolism, and close monitoring of cardiac rhythm during insufflation of carbon dioxide. The patients who had previous surgery should be considered as a risk population.

Cerebral air embolism occurred in a patient undergoing posterior fossa surgery performed in the sitting position for acoustic neuroma removal. The patient experienced two episodes of venous air embolism, as evidenced by precordial Doppler, end-tidal carbon dioxide reduction, and oxygen desaturation. In both cases, air was aspirated from the central venous catheter; during the second episode there was arterial hypotension and electrocardiogram changes, and air bubbles were visualized in the cerebellar arteries. The patient did not regain consciousness after surgery and developed early tonic-clonic convulsions and electroencephalogram status epilepticus, which was treated with barbiturate coma. Intracardiac septal defects were not detected by transesophageal echocardiography, and computerized tomography of the brain demonstrated multifocal discrete ischemic areas in the cerebral hemispheres. The patient died 6 days after surgery without having regained consciousness. This case appears to represent the occurrence of transpulmonary passage of venous air embolism.

Background: A double-lumen multiorifice catheter has been developed to potentially enhance accurate electrocardiographic central venous localization and resuscitation from a massive venous air embolism (VAE). This double-lumen multiorifice catheter was compared to a Bunegin-Albin multiorifice catheter for flow characteristics, air aspiration efficiency, and efficacy in resuscitating swine from a lethal VAE., Methods: Flow characteristics of both catheters were determined by aspirating both agitated and unagitated citrated swine blood with a 50-ml syringe. Swine were anesthetized with halothane and positioned to approximate a modified sitting craniotomy position (45-degree elevation). By a random block method, 24 swine were assigned to either catheter (n = 12 each catheter) for the initial air aspiration. Catheters were positioned, using intravenous electrocardiography, with the distal aspiration orifice in the high right atrium. A 5-ml/kg air embolism was administered over 30 s into the sagittal sinus, and the swine were resuscitated by aspirating air through the multiorifice catheters and then positioning the swine horizontally. Surviving animals were allowed to recover for 60 min. The initial catheter was exchanged and repositioned in the high right atrium using intravenous electrocardiography. A 5-ml/kg air embolus was administered, and the swine were resuscitated as in the first challenge. Surviving swine recovered for 60 min, repositioned, and administered a third 5-ml/kg air embolism. On this final challenge, no attempt was made to resuscitate the animal by aspirating the multiorifice catheter., Results: Flow characteristics of both catheters were similar in the unagitated blood (195.3 +/- 1.9 vs. 196.7 +/- 2.5 ml/min). The flow rate of agitated blood through the double-lumen multiorifice catheter was 14% greater than through the Bunegin-Albin catheter (136.3 +/- 6.8 vs. 117 +/- 5.9 ml/min, P = 0.001). Forty-three air embolism trials were conducted at 5 ml/kg. All nine trials at 5 ml/kg without air aspiration resulted in death. Five animals died during the embolism dose determination trials, and four died during the third embolism challenge. The use of a multiorifice catheter for aspiration after a VAE enhanced survival after a 5-ml/kg sagittal sinus air embolus (14/34 vs. 0/9, P = 0.02). Although the double-lumen multiorifice catheter was more efficient than the Bunegin-Albin catheter in percentage of air retrieved (37.7 +/- 12.0 vs. 29.7 +/- 10.1, P = 0.042). Aspiration of the VAE with the double-lumen multiorifice catheter successfully rescued 9 of the 15 trials, and aspiration using the Bunegin-Albin catheter resuscitated 5 of the 19 (P = 0.08)., Conclusions: Multiorifice catheters are effective in resuscitating swine from a lethal VAE. The double-lumen multiorifice catheter evaluated aspirated a larger percentage of the VAE but was not statistically more effective than the Bunegin-Albin catheter in resuscitating the animals. Based on these findings of improved flow rate and efficiency in air aspiration, further investigation of this double-lumen multiorifice catheter is warranted.