Effect of air and heliox as carrier gas on CO2 transport in a model of high-frequency oscillation comparing two oscillators

OBJECTIVE: To study the effect of carrier gas on CO(2) transport during high-frequency oscillatory ventilation in a closed model. DESIGN: In vitro model study. SETTING: Respiratory research laboratory affiliated with a tertiary center for pediatric critical care. SUBJECT: In vitro, closed-lung model consisting of a glass tube (9.8 x 1000 mm) covered at each end with balloons. INTERVENTION: Air or heliox (80:20) at constant pressure was oscillated inside the model, comparing the Sensormedics 3100A and Hummingbird BMO-20N oscillators at equal amplitude. MEASUREMENTS AND MAIN RESULTS: Tracer gas (CO(2)) was injected at one end of the model, and CO(2) concentration was measured at the opposite end. Speed of CO(2) transport was expressed as the time for the CO(2) concentration to reach 63% of the final concentration (the time constant). In room air, using the Hummingbird oscillator and increasing frequency stepwise from 5 to 20 Hz, the time constant decreased from 2813 to 457 secs (p =.05). Using the Sensormedics oscillator in room air at increasing frequency from 5 to 15 Hz, the time constant decreased from 1584 to 551 secs (p =.05). In heliox, using the Hummingbird oscillator, the speed of CO(2) transport increased by 85% (p =.029) at 5 Hz and by 28% (p =.05) at 15 Hz. With the Sensormedics oscillator using heliox, the speed of CO(2) transport increased by 16% at 5 Hz (p =.009) and 52% at 15 Hz (p =.008). Proportionally, the increase in CO(2) transport with heliox was greater at 5 Hz for the Hummingbird oscillator and at 15 Hz for the Sensormedics oscillator. CONCLUSIONS: In a closed model, we showed that during high-frequency oscillatory ventilation in room air, CO(2) transport increases with increasing frequency for both ventilators. Using heliox as carrier gas significantly augmented CO(2) transport, but the increase is frequency and device dependent. The effect of heliox on oscillator performance and the clinical applicability of our findings require further study.     

Gastric mesenchymal tumors as incidental findings during Roux-en-Y gastric bypass

Background

Occurrences of mesenchymal tumors have been more recognized in recent years, and the incidental diagnosis of these lesions during bariatric surgery has been previously reported.

A 3-D model-based registration approach for the PET,MR and MCG cardiac data fusion

In this paper, a new approach is presented for the assessment of a 3-D anatomical and functional model of the heart including structural information from magnetic resonance imaging (MRI) and functional information from positron emission tomography (PET) and magnetocardiography (MCG). The method uses model-based co-registration of MR and PET images and marker-based registration for MRI and MCG. Model-based segmentation of MR anatomical images results in an individualized 3-D biventricular model of the heart including functional parameters from PET and MCG in an easily interpretable 3-D form.     

Bariatric surgery and periodontal status: A systematic review with meta-analysis

Objective

To review and analyze periodontal clinical parameters after bariatric surgery.

Abdominal actinomycosis presenting as a small-bowel obstruction

A 48-year-old female, presented as a case of acute abdomen with a small-bowel obstruction and a palpable hypogastric mass, was urgently operated. Laparotomy revealed a tumor mass of unknown origin that included a loop of the small bowel by compressing it. Resection of the tumor including a portion of the large and small bowel was performed, and pathohistological examination revealed actinomycosis. The cause of abdominal actinomycosis in this patient could be the implantation of an intrauterine device nine years prior to the operation.     

Vasculitis affecting the kidney: presentation, histopathology and long-term outcome

Fifty-three patients who by clinical and/or histological criteria were judged to have vasculitis affecting the kidney were reviewed. Patients with systemic lupus or Sch?nlein-Henoch purpura were excluded. Segmental necrotising glomerulitis was taken as a manifestation of vasculitis ('microscopic polyarteritis'). Those patients in whom vasculitis was confined to glomerular capillaries were compared with those who in addition had vascular lesions outside the glomeruli. The two groups were found to have identical clinical features. Clinical presentation was predominantly extrarenal, and exclusively renal in only two. Three patients were classified histologically as Wegener's granulomatosis, four had malignant tumours and two relapsing polychondritis. Hepatitis B surface antigen was absent in all of 37 patients tested. Renal disease presented with microscopic haematuria and minor proteinuria in the majority (32) but 16 patients presented with rapid deterioration of renal function, including seven with anuria. Histologically 42 patients showed segmental necrotising glomerulitis ('microscopic polyarteritis'), six diffuse proliferative glomerulonephritis,and in five only minor or ischaemic glomerular changes were present. Crescents were found in 41/42 of those with segmental necrotising glomerulitis, nd involved more than 50 per cent of glomeruli in 15 patients. Immunohistochemical studies were generally negative except the fibrin. Electron microscopy showed no evidence of immune deposits in necrotising glomerulitis, but these were present in 2/6 patients with diffuse proliferative glomerulonephritis. Overall prognosis was poor, 35 patients having died, 20 early in the course of the disease and 15 later. Oligoanuria and extensive crescent formation were adverse signs. Survivals were 54, 38 and 34 per cent at one, five and 10 years respectively. Of those who survived the initial illness, 12 were stable with apparently inactive disease, whilst 16 continued to show clinical signs of activity and required treatment. A variety of treatments was employed including oral and intravenous corticosteroids, immunosuppressive agents, anticoagulants; only one patient was treated by plasmapheresis. It is difficult to draw any firm conclusions as to the efficacy of treatment and survival rates remain unsatisfactory.