[Management of Stent-graft migration with obstruction of supra-aortic vessel during an endovascular procedure for aortic isthmus rupture]. / Migration d'endoprothèse thoracique avec occlusion des troncs supra-aortiques en per-procédure pour rupture isthmique ; prise en charge.

The endovascular approach is widely used in the management of aortic isthmic rupture. Even if it remains less invasive than conventional surgery, a life-threatening complications are possible. We report the case of a young female patient presenting a stent-graft migration during the deployment with total obstruction of the supra-aortic vessels. We describe the therapeutic management with a cerebral rescue procedure followed by a delayed surgical repair.

Case series of aortic arch disease treated with branched stent-grafts.

BACKGROUND: Surgical repair of aortic arch pathology is complex and associated with significant morbidity and mortality. Alternative approaches have been developed to reduce these risks, including the use of thoracic stent-grafts with fenestrations or in combination with bypass procedures to maintain supra-aortic trunk blood flow. Branched stent-grafts are a novel approach to treat aortic arch pathology. METHODS: Consecutive patients with aortic arch disease presenting to a single university hospital vascular centre were considered for branched stent-graft repair (October 2010 to January 2017). Patients were assessed in a multidisciplinary setting including a cardiologist, cardiac surgeon and vascular surgeon. All patients were considered prohibitively high risk for standard open surgical repair. The study used reporting standards for endovascular aortic repair and PROCESS (Preferred Reporting of Case Series in Surgery) guidelines. RESULTS: Some 30 patients (25 men) underwent attempted branch stent-graft repair. Mean age was 68 (range 37-84) years. Eighteen patients had chronic aortic dissection, 11 patients had an aneurysm and one had a penetrating ulcer. Fourteen patients had disease in aortic arch zone 0, six in zone 1 and ten in zone 2. Twenty-five patients had undergone previous aortic surgery and 24 required surgical revascularization of the left subclavian artery. Technical success was achieved in 27 of 30 patients. Four patients had an endoleak (type Ia, 1; type II, 3). The in-hospital mortality rate was three of 30. Mean length of follow-up was 12·0 (range 1·0-67·8) months, during which time 12 patients required an aortic-related reintervention. CONCLUSION: Repair of aortic arch pathology using branched stent-grafting appears feasible. Before widespread adoption of this technology, further studies are required to standardize the technique and identify which patients are most likely to benefit.

Changes in Renal Anatomy After Fenestrated Endovascular Aneurysm Repair.

OBJECTIVE: To assess short- and long-term movement of renal arteries after fenestrated endovascular aortic repair (FEVAR). METHODS: Consecutive patients who underwent FEVAR at one institution with a custom-made device designed with fenestrations for the superior mesenteric (SMA) and renal arteries, a millimetric computed tomography angiography (CTA), and a minimum of 2 years' follow-up were included. Angulation between renal artery trunk and aorta, clock position of the origin of the renal arteries, distance between renal arteries and SMA, and target vessel occlusion were retrospectively collected and compared between the pre-operative, post-operative (<6 months), and last (>12 months) CTA. RESULTS: From October 2004 to January 2014, 100 patients met the inclusion criteria and 86% of imaging was available for accurate analysis. Median follow-up was 27.3 months (22.7-50.1). There were no renal occlusions. A significant change was found in the value of renal trunk angulation of both renal arteries on post-operative compared with pre-operative CTA (17° difference upward [7.5-29], p < .001), but no significant change thereafter (p = .5). Regarding renal clock positions (7.5° of change equivalent to 15 min of renal ostial movement): significant anterior change was found between post-operative and pre-operative CTA (15 min [0-30], p = .03 on the left and 15 min [15-30], p < .001 on the right), without significant change thereafter (15 min [0-30], p = .18 on the left and 15 min [0-15] on the right, p = .28). No changes were noted on the distance between renal and SMA ostia (difference of 1.65 mm [1-2.5], p = .63). CONCLUSION: The renal arteries demonstrate tolerance to permanent changes in angulation after FEVAR of approximately 17° upward trunk movement and of 15-30 min ostial movement without adverse consequences on patency after a median of more than 2 years' follow-up. The distance between the target vessels remained stable over time. These results may suggest accommodation to sizing errors and thus a compliance with off the shelf devices in favourable anatomies.

Editor's Choice - Subsequent Results for Arch Aneurysm Repair with Inner Branched Endografts.

OBJECTIVES: The aim was to evaluate the current results of aortic arch aneurysm repair using inner branched endografts performed in three high volume aortic endovascular centers and to compare them to the pioneering global experience with this technology. METHODS: Included patients underwent repair of aortic arch aneurysms >55 mm in diameter using inner branched endograft technology between April 2013 and November 2014. All patients were deemed unfit for open surgery. Inner branches were designed to perfuse the brachiocephalic trunk and the left common carotid artery in all cases. A left subclavian artery (LSA) revascularization was performed prior to the arch endovascular repair. Data were collected retrospectively in an electronic database. Parameters included length of procedure, fluoroscopy time, contrast volume, technical success, presence of endoleaks, early and late complications, and mortality. RESULTS: Twenty-seven patients were included in the study. Technical success was achieved in all cases. No patients died during the 30 day post-operative period. Early neurologic events included two major strokes (7.4%) and one minor stroke (3.7%). Transient spinal cord ischemia with full recovery was observed in two patients (7.4%). Four patients (14.8%) underwent early (<30 day) re-interventions; these were for an access complication, an ischemic limb and exploration of the left ventricle through a sternotomy in two patients. During follow up (median 12 months), one patient (3.7%) died from a remote thoraco-abdominal aneurysm rupture. There were three Type 2 endoleaks (11.1%). Two re-interventions (7.4%) were performed, one to treat a Type 2 endoleak and one to treat a septic false aneurysm. A significant decrease in overall mortality was observed when comparing patients from the early experience with patients from the current report. CONCLUSIONS: The early outcomes associated with this technology are favorable. Branched endografting of aortic arch aneurysms should be considered in patients unfit for open surgery.

Early Experience of Endovascular Repair of Post-dissection Aneurysms Involving the Thoraco-abdominal Aorta and the Arch.

OBJECTIVES: Outcomes are reported in management of post-dissection aneurysms involving the aortic arch and/or thoraco-abdominal segment (TAAA) treated with fenestrated and branched (complex) endografts. METHODS: This report includes all patients with chronic post-dissection aneurysms >55 mm in diameter, deemed unfit for open surgery, treated using complex endografts between October 2011 and March 2015. When appropriate, staged management strategies including left subclavian artery revascularization, thoracic endografting, dissection flap fenestration or tear enlargement, and other endovascular procedures were performed at least 3 weeks prior to definitive complex endovascular repair. The following outcome data were collected prospectively at discharge, 12 months and annually thereafter: technical success, endoleaks, target vessel patency, false lumen patency, aneurysm diameter, major and minor complications, re-interventions, and mortality. RESULTS: The cohort comprised 23 patients with a median age of 65 years. Staged procedures were performed in 14 patients (61%). Seven patients with dissections involving the arch were treated with inner branched endografts, and 16 TAAA patients were treated with fenestrated or branched endografts. The technical success rate was 71% following arch repair and 100% following TAAA repair. During early follow up, one of the arch group patients died and one in the TAAA group suffered spinal cord ischemia. The median follow up was 12 months (range 3-48), during which time one patient died of causes unrelated to aneurysm or treatment. Two early re-interventions were performed in the arch group to correct access vessel complications and there were a further two late re-interventions in the TAAA group to treat endoleaks. All target vessels (n = 72) remained patent. CONCLUSIONS: This experience indicates that complex endovascular repair of post-dissection aneurysms is a viable alternative to open repair in patients deemed unfit for open surgery. There are insufficient data to allow comparison with the outcome of open surgery in anatomically similar, but fit, patients.

Renal Outcomes Following Fenestrated and Branched Endografting.

OBJECTIVE: The purpose of this study was to analyze immediate and long-term renal outcomes (renal function and renal events) after fenestrated (FEVAR) and branched endovascular aortic aneurysm repair (BEVAR). METHODS: All FEVAR and BEVAR performed between October 2004 and October 2012 were included in this study. Post-operative acute renal failure (ARF) was defined according to the RIFLE criteria. Renal volume (calculated with a 3D workstation) and estimated glomerular filtration rate (GFR) (estimated with the Modification of Diet in Renal Disease [MDRD] formula) were evaluated before the procedure, before discharge, 12 months after, and yearly thereafter. Renal stent occlusion, dissection, fracture, stenosis, kink, renal stent related endoleak, and renal stent secondary intervention were all considered "renal composite events" and analyzed. A time to event analysis was performed for renal events and secondary renal interventions. RESULTS: 225 patients were treated with FEVAR and BEVAR. Renal target vessels (n = 427) were perfused by fenestrations (n = 374), or branches (n = 53). Median follow up was 3.1 years (2.9-3.3 years). Technical success was achieved in 95.5% of patients. Post-operative ARF was seen in 64 patients (29%). Mean total renal volume and eGFR at 1 year, 2 year, and 3 year follow up were significantly lower when compared with pre-operative levels (after BEVAR and FEVAR); the decrease at 3 years was 14.8% (6.7%; 22.2%) (p = .0006) for total renal volume and 14.3% (3.1%; 24.3%) (p = .02) for eGFR. The 30 day and 5 year freedom from renal composite event was 98.6% (95.8-99.6%) and 84.5% (76.5-89.9%) after FEVAR and BEVAR (NS). The 30 day and 5 year freedom from renal occlusion was 99.5% (96.7-99.9%) and 94.4% (89.3-97.1%) after FEVAR and BEVAR (NS). CONCLUSION: FEVAR and BEVAR are durable options for the treatment of complex aortic aneurysms and are associated with low renal morbidity, without differences between devices types. The clinical impact of decreasing renal volume over time in these patients is yet to be fully understood.

Benefits of Completion 3D Angiography Associated with Contrast Enhanced Ultrasound to Assess Technical Success after EVAR.

OBJECTIVES: This study evaluated a new strategy to assess technical success after standard and complex endovascular aortic repair (EVAR), combining completion contrast enhanced cone beam computed tomography (ceCBCT) and post-operative contrast enhanced ultrasound (CEUS). METHODS: Patients treated with bifurcated or fenestrated and branched endografts in the hybrid room during the study period were included. From December 2012 to July 2013, a completion angiogram (CA) was performed at the end of the procedure, and computed tomography angiography (CTA) before discharge (group 1). From October 2013 to April 2014, a completion ceCBCT was performed, followed by CEUS during the 30 day post-operative period (group 2). The rate of peri-operative events (type I or III endoleaks, kinks, occlusion of target vessels), need for additional procedures or early secondary procedures, total radiation exposure (mSv), and total volume of contrast medium injected were compared. RESULTS: Seventy-nine patients were included in group 1 and 54 in group 2. Peri-operative event rates were respectively 8.9% (n = 7) and 33.3% (n = 18) (p = .001). Additional procedures were performed in seven patients (8.9%) in group 1 versus 17 (31.5%) in group 2 (p = .001). Two early secondary procedures were performed in group 2 (3.7%), and three (3.8%) in group 1 (p = .978). Median radiation exposure due to CBCT was 7 Gy cm(2) (5.25-8) (36%, 27%, and 9% of the total procedure exposure, respectively for bifurcated, fenestrated, and branched endografts). CEUS did not diagnose endoleaks or any adverse events not diagnosed by ceCBCT. Overall radiation and volume of contrast injected during the patient hospital stay in groups 1 and 2 were 34 (25.8-47.3) and 11 (5-20.5) mSv, and 184 (150-240) and 91 (70-132.8) mL respectively (reduction of 68% and 50%, p < .001). CONCLUSIONS: Completion ceCBCT is achievable in routine practice to assess technical success after EVAR. Strategies to evaluate technical success combining ceCBCT and CEUS can reduce total in hospital radiation exposure and contrast medium volume injection.

Current and future perspectives in the repair of aneurysms involving the aortic arch.

The repair of aneurysms involving the aortic arch is technically and physiologically demanding. Historically, these aneurysms have been treated using open surgical techniques that require cardiopulmonary bypass and deep hypothermic circulatory arrest. Many patients have been deemed "untreatable" and among those selected for surgery there are reported risks of death in 2% to 16.5% and stroke rates ranging from 2% to 18%. "Hybrid arch repair" combines one of a number of open surgical procedures (to secure a proximal landing zone for an endograft) with subsequent or immediate placement of an endograft in the arch and descending aorta. Although this concept is described as "minimally invasive" because it avoids aortic cross-clamping and hypothermic circulatory arrest, the morbidity and mortality rates remain considerable (mortality 0% to 15%, stroke 0% to 11%). Ongoing development of endograft technology has enabled total endovascular repair of complex aortic aneurysms involving the visceral segment, using fenestrated and branched endografts. Encouraging early results in this anatomy have inspired extension of the concept to include the aortic arch and great vessels. These strategies can be considered in patients generally at high-risk for the conventional procedures. However, the endeavour is at an early stage of its development and the arch poses unique challenges including the potential for stroke, angulation of the arch and the great vessel ostia to the arch, extremely high volume flow, three-dimensional pulsation and rotation with the cardiac cycle and the proximity of the aortic valve and coronary arteries.

The impact of early pelvic and lower limb reperfusion and attentive peri-operative management on the incidence of spinal cord ischemia during thoracoabdominal aortic aneurysm endovascular repair.

OBJECTIVE/BACKGROUND: Spinal cord ischemia (SCI) is a devastating complication following endovascular thoracoabdominal aortic aneurysm (TAAA) repair. In an attempt to reduce its incidence two peri-procedural changes were implemented by the authors in January 2010: (i) all large sheaths are withdrawn from the iliac arteries immediately after deploying the central device and before cannulation and branch extension to the visceral vessels; (ii) the peri-operative protocol has been modified in an attempt to optimize oxygen delivery to the sensitive cells of the cord (aggressive blood and platelet transfusion, median arterial pressure monitoring >85 mmHg, and systematic cerebrospinal fluid drainage). METHODS: Between October 2004 and December 2013, 204 endovascular TAAA repairs were performed using custom made devices manufactured with branches and fenestrations to maintain visceral vessel perfusion. Data from all of these procedures were prospectively collected in an electronic database. Early post-operative results in patients treated before (group 1, n = 43) and after (group 2, n = 161 patients) implementation of the modified implantation and peri-operative protocols were compared. RESULTS: Patients in groups 1 and 2 had similar comorbidities (median age at repair 70.9 years [range 65.2-77.0 years]), aneurysm characteristics (median diameter 58.5 mm [range 53-65 mm]), and length of procedure (median 190 minutes [range 150-240 minutes]). The 30 day mortality rate was 11.6% in group 1 versus 5.6% in group 2 (p = .09). The SCI rate was 14.0% versus 1.2% (p < .01). If type IV TAAAs were excluded from this analysis, the SCI rate was 25.0% (6/24 patients) in group 1 versus 2.1% (2/95 patients) in group 2 (p < .01). CONCLUSION: The early restoration of arterial flow to the pelvis and lower limbs, and aggressive peri-operative management significantly reduces SCI following type I-III TAAA endovascular repair. With the use of these modified protocols, extensive TAAA endovascular repairs are associated with low rates of SCI.

Chronic dissection - indications for treatment with branched and fenestrated stent-grafts.

The treatment of chronic aortic dissection is a major challenge for the vascular surgeon. Close imaging follow-up after the acute episode frequently identifies dilation of untreated aortic segments. Aortic dissection often extends to both the supra-aortic trunks and to the visceral aorta. The poor medical condition that often characterizes these patients may preclude extensive open surgical repair. Recent advances in endovascular techniques provide a valid alternative to open surgery. These complex lesions can now be managed using thoracic branched and fenestrated endografts. However, clinical data are scarce and only 3 small series from 3 high-volume aortic centers are currently available. Careful anatomical study on 3D workstations is mandatory to select patients that are candidates for complex endovascular exclusion; a specific focus on the available working space within the true lumen, extension to the arch and/or the visceral/renal arteries, and false lumen perfusion of visceral vessels is required. An excellent understanding of those anatomic details demands high-quality preoperative CTA. Intraoperative advanced imaging applications are a major adjunct in the achievement of technical success.

Total endovascular treatment of an aortic arch aneurysm in a patient with a mechanical aortic valve.

INTRODUCTION: Endovascular repair of aortic arch aneurysms using an inner-branched device is a new treatment option for patients unfit for open surgery. There are many anatomical restrictions, such as the presence of a mechanical aortic valve that can contraindicate this complete endovascular approach. REPORT: A new delivery system to overcome this issue has been developed. This new system was used to treat an aortic arch aneurysm 77 mm in diameter in a 37-year-old patient with Marfan's syndrome. The patient was considered to be at major risk for open surgery because of severe respiratory insufficiency following a second sternotomy. DISCUSSION: Total endovascular arch aneurysm repair is no longer contraindicated in patients with a mechanical aortic valve.

Centerline is not as accurate as outer curvature length to estimate thoracic endograft length.

BACKGROUND: To assess the accuracy of the aortic outer curvature length for thoracic endograft planning. METHODS: Seventy-four patients (58 men, 66.4 ± 14 years) who underwent thoracic endovascular aortic repair between 2009 and 2011 treated with a Cook Medical endograft were enrolled in this retrospective study. Immediate postoperative CT scans were analysed using EndoSize software. Three vessel lengths were computed between two fixed landmarks placed at each end of the endograft: the straightline (axial) length, the centerline length and the outer curvature length. A tortuosity index was defined as the ratio of the centerline length/straightline length. A Student t test and a Pearson correlation coefficient were used to examine the results. RESULTS: We found a significant difference between the centerline length (135.4 ± 24 mm) and that of the endograft (160 ± 29 mm) (p < .0001). This difference correlates with the tortuosity index (r = .818, p < .0001), the endograft length (r = .587, p < .0001), and the diameter of the endograft (r = .53, p < .0001). However, the outer curvature length (161.3 ± 29 mm) and the endograft length (160 ± 29 mm) were similar (p = .792). CONCLUSION: The outer curvature length more accurately reflects that of the deployed endograft and may prove more accurate than centerlines in planning thoracic endografts.

Technical note and results in the management of anatomical variants of renal vascularisation during endovascular aneurysm repair.

INTRODUCTION: The revascularisation of large (>3 mm) renal arteries emerging from the proximal sealing zone or off the aneurismal wall can be challenging during endovascular aortic aneurysm repair. In this article, we describe various endovascular techniques using custom-made endografts to treat these complex variant anatomies. CASES: Nine patients deemed unfit for open repair with unusual renal vascularisation associated with aortic aneurysms were treated by endovascular means. After three-dimensional (3D) reconstructions on a dedicated workstation, custom-made devices were designed and manufactured. The revascularisation of multiple renal arteries and aberrant origins of renal arteries, associated or not with pelvic kidney or horseshoe kidney, was managed using fenestrated and branched endografts. RESULTS: All target vessels were patent on computed tomography (CT) scan and contrast-enhanced ultrasound evaluation before discharge as well as on the 6-month follow-up. One patient presented a decrease of postoperative glomerular filtration rate over 30% but did not require dialysis. No sac enlargement was depicted, and no reintervention was performed during follow-up. Three type 2 endoleaks were diagnosed. CONCLUSION: Endovascular treatment with fenestrated and branched endografts should be considered in challenging renal artery anatomies in patients unfit for open repair.

A matched, case-control study of the association between Schistosoma japonicum and liver and colon cancers, in rural China.

A study of liver and colon cancers and their association with a previous diagnosis of schistosomiasis was performed in rural Sichuan, China. The data analysed came from 127 liver-cancer and 142 colon-cancer patients, each matched, by age, gender, hospital and township, with one or two controls. The cancer cases were identified from the hospital records of three Sichuan counties (all of which have some level of endemic schistosomiasis japonicum): Meishan (66 liver and 54 colon cases), Pujiang (16 liver and 22 colon cases) and Xichang (45 liver and 66 colon cases). Each control was selected using the hospital records for the same year the matched case of cancer was diagnosed, when the control had been found to have an illness other than cancer. Previous schistosomal infection was determined by examining the medical records at the county hospitals, searching the records at the local schistosomiasis-control stations or health-surveillance units, and, when no written record could be found, by interviews with the subjects or their relatives. Given the extremely strong association between hepatitis and liver cancer in China, only data from hepatitis-negative pairs were used in the analyses. Previous schistosomal infection was found to be significantly associated with both liver cancer (odds ratio = 3.7; 95% confidence interval = 1.0-13) and colon cancer (odds ratio = 3.3; 95% confidence interval = 1.8-6.1). The results indicate a fraction of disease attributable to schistosomiasis of 24% for colon cancer, and (among the hepatitis-negative population) one of 27% for liver cancer.

Helium-oxygen mixture does not improve gas exchange in mechanically ventilated children with bronchiolitis.

STATEMENT OF FINDINGS: Varying concentrations of helium-oxygen (heliox) mixtures were evaluated in mechanically ventilated children with bronchiolitis. We hypothesized that, with an increase in the helium:oxygen ratio, and therefore a decrease in gas density, ventilation and oxygenation would improve in children with bronchiolitis. Ten patients, aged 1-9 months, were mechanically ventilated in synchronized intermittent mandatory ventilation (SIMV) mode with the following gas mixtures delivered at 15-min intervals: 50%/50% nitrogen/oxygen, 50%/50% heliox, 60%/40% heliox, 70%/30% heliox, and return to 50%/50% nitrogen/oxygen. The use of different heliox mixtures compared with 50%/50% nitrogen/oxygen in mechanically ventilated children with bronchiolitis did not result in a significant or noticeable decrease in ventilation or oxygenation.

Management of pediatric liver injuries: a 13-year experience at a pediatric trauma center.

PURPOSE: This study of traumatic liver injuries (LI) in children reviews the authors' management and identifies the indications for surgical intervention. METHODS: A total of 11,761 admissions over 13 years to a regional pediatric trauma center were surveyed. RESULTS: LI were identified in 328 children. Mechanisms included 39% pedestrians struck by a vehicle, 34% motor vehicle occupants, 13% falls or discrete blows to the abdomen, 5% bicycle injuries, 5% child abuse, and 4% penetrating injuries. Eighty-seven of patients with LI were treated nonoperatively with a mortality rate of 17%. Six percent of deaths were attributed to the LI and massive hemorrhage, all of which presented with cardiopulmonary resuscitation (CPR) in progress, with the remainder of deaths attributed to massive head, neck, or chest injuries (HNCI, 90%) and sepsis (4%). Surgery was performed in 13% of all LI and included major hepatic vascular injury (MHVI) repairs (34%), hepatorrhaphies (34%), lobectomies (27%), and biliary repairs (4%). Excluding the nonoperative group deaths, the need for blood transfusion of more than 25 mL/kg in the first 2 hours as an indicator of surgical necessity or a MHVI had, respectively, a sensitivity of 34% and 67%, specificity of 98% and 97%, positive predictive value of 79% and 53%, negative predictive value of 89% and 98%, and prediction accuracy of 88% and 95%. In the surgical management group, the mortality rate was 23% with 40% of deaths attributed to MHVI, 30% a combination of MHVI and HNCI, 20% massive HNCI, and 10% sepsis. CONCLUSIONS: The majority of pediatric LI are not associated with hemodynamic instability and can be successfully managed nonoperatively (72%). Hemodynamic instability, as defined by the need for blood transfusion in excess of 25 mL/kg within the first 2 hours, was a strong indicator of a MHVI, which was often a lethal injury (70%).

Percutaneous catheter drainage of tension pneumatocele, secondarily infected pneumatocele, and lung abscess in children.

OBJECTIVE: To describe the use of percutaneous catheter drainage of tension pneumatocele, secondarily infected pneumatocele, and lung abscess in children. DESIGN: Retrospective case series. SETTING: A 24-bed pediatric intensive care unit. PATIENTS: Patients with tension pneumatocele, secondarily infected pneumatocele, or lung abscess. Tension pneumatocele was defined as an expanding intraparenchymal cyst compressing adjacent areas of the lung. Infected pneumatocele and lung abscess were defined, respectively, as intraparenchymal thin-walled cyst or thick-walled cavity containing an air-fluid level and purulent fluid. INTERVENTIONS: Seven pneumatoceles/lung abscesses were percutaneously drained in five patients. After computed tomography of the chest was obtained to localize the optimum site for drainage, a modified Seldinger technique was used to insert an 8.5-Fr soft catheter percutaneously into the cyst/cavity. The catheter was left in place until drainage (fluid and air) stopped. MEASUREMENTS AND MAIN RESULTS: All patients had clinical and radiologic improvement and were afebrile within 24 hrs after drainage. Bacterial culture grew aerobic bacteria from three cysts/cavities, anaerobic bacteria from one, and mixed bacteria from three. One patient had three secondarily infected pneumatoceles. Four of five secondarily infected pneumatoceles were under tension in two patients receiving mechanical ventilation. In both patients, the trachea was extubated within 24 hrs of drainage after prolonged mechanical ventilation. The number of days the catheter was in place ranged from 1 to 20 days. CONCLUSIONS: Percutaneous catheter drainage of tension pneumatocele, secondarily infected pneumatocele, and lung abscess can be performed safely and effectively in children. Early drainage is helpful, both as a diagnostic and therapeutic procedure. Drainage of tension pneumatocele may assist in weaning from mechanical ventilation. Computed tomography of the chest is helpful in determining the optimum site for percutaneous drainage.

Benzene toxicokinetics in humans: exposure of bone marrow to metabolites.

A three compartment physiologically based toxicokinetic model was fitted to human data on benzene disposition. Two separate groups of model parameter derivations were obtained, depending on which data sets were being fitted. The model was then used to simulate five environmental or occupational exposures. Predicted values of the total bone marrow exposure to benzene and cumulative quantity of metabolites produced by the bone marrow were generated for each scenario. The relation between cumulative quantity of metabolites produced by the bone marrow and continuous benzene exposure was also investigated in detail for simulated inhalation exposure concentrations ranging from 0.0039 ppm to 150 ppm. At the level of environmental exposures, no dose rate effect was found for either model. The occupational exposures led to only slight dose rate effects. A 32 ppm exposure for 15 minutes predicted consistently higher values than a 1 ppm exposure for eight hours for the total exposure of bone marrow to benzene and the cumulative quantity of metabolites produced by the bone marrow. The general relation between the cumulative quantity of metabolites produced by the bone marrow and the inhalation concentration of benzene is not linear. An inflection point exists in some cases leading to a slightly S shaped curve. At environmental levels (0.0039-10 ppm) the curve bends upward, and it saturates at high experimental exposures (greater than 100 ppm).

Septic pulmonary emboli complicating mastoiditis: Lemierre's syndrome revisited.

Deep neck-space infections may cause potentially life-threatening complications of head and neck infections. Lateral pharyngeal space infections in particular predispose to development of suppurative jugular vein thrombosis, which may be associated with anaerobic bacteremia and septic pulmonary emboli (Lemierre's syndrome). We describe a case of Lemierre's syndrome, a very rare entity in the antibiotic era, complicating mastoiditis. Surgical debridement and drainage in conjunction with antibiotic therapy resulted in prompt improvement in the patient's condition.

Model parameter estimation and analysis: understanding parametric structure.

We developed three algorithms to facilitate an analysis of the parameter combinations (PASS points) that fit experimental data to a desired degree of accuracy. The clustering algorithm separates PASS points into clusters (PASS clusters) as a preliminary step for the following geometrical parametric analyses. The PASS region reconstruction algorithm defines the space of a PASS cluster to allow further parametric structural analysis. The feasible parameter space expansion algorithm produces a complete PASS cluster to be used for model predictions to evaluate the effects of variability and uncertainty. These algorithms are demonstrated using two pharmacokinetic models; a single compartment model for procainamide and a three-compartment physiologically based model for benzene. We found a more thorough representation of the parameter space than previously considered. Thus, we obtained model predictions that describe better the variability in population responses. In addition, we also parametrically identified a subpopulation that may have a higher risk for cancer.