High‐frequency ventilation with the Dräger Babylog 8000plus: measuring the delivered frequency

Background: Ventilator frequency is one of the determinants of tidal volume delivery during high‐frequency ventilation. Clinicians increasingly use data on ventilator displays to inform their decisions. Aim: To measure the frequencies delivered by the Dräger Babylog 8000plus ventilator when used in high‐frequency mode. Methods: Ventilator waveforms using a test lung were recorded at the full range of settings 5–20 Hz using Spectra software at 1000 Hz. The changes in frequency produced by a 1‐ Hz change in set frequency were calculated. Actual and displayed frequencies were compared. Results: For settings up to 12 Hz, median (range) difference between set and delivered frequencies was 0 (?0.4 to +0.1) Hz. Above 12 Hz, delivered frequency varied by ?0.3 (?1.9 to +0.3) Hz. For 1‐ Hz changes in frequency settings, in the range 5–12 Hz, 1‐ Hz changes produced a change in delivered frequency of 1.0 (0.6–1.4) Hz. Above 12 Hz, the corresponding changes were 0.7 (0–2.9) Hz. The ventilator displays the set frequency during operation rather than the delivered frequency. Conclusion: At 12 Hz and below, the differences between set and delivered frequencies were relatively small compared with those at 13 Hz and higher. Above 13 Hz, the difference between set and delivered frequencies was up to 2.9 Hz. Some frequency setting changes did not result in a change in delivered frequency.     

In situ saphenous vein bypass grafts: angiographic evaluation and interventional repair of complications

In situ saphenous vein grafts are being used with increasing frequency for bypass procedures involving the femoral and popliteal arteries. Complications of these procedures include anastomotic stenoses and persistent arteriovenous fistulae that may result in failure of the graft. Balloon angioplasty and embolotherapy with detachable balloons were employed successfully in three or four recent cases of patients with complications from in situ grafts. Tailored angiography is essential for evaluating in situ grafts, and interventional techniques are extremely useful for managing complications.     

Pheochromocytoma and paraganglioma: comparison of MR imaging with CT and I-131 MIBG scintigraphy

To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice.     

The prognostic factors for the radiation treatment of the cerebral metastases from breast carcinoma]

Complex mechanisms of various nature, not only physical, can influence the patterns of metastases. We compared the patients with recurrences to the brain as the only metastatic site from breast cancer with the patients relapsing in the brain and other organs. All cases were staged and treated following professional protocols. When brain metastases were diagnosed, the patients were accurately restaged before being submitted to radiation therapy; the whole brain was irradiated with various total doses and the same fractionation. The patients underwent clinical examination before and after irradiation. Survival analysis was carried out using the product-limit method considering the following periods: total survival, relapse-free survival, elapsed time till the appearance of brain metastases, and survival after radiation therapy. The cases were grouped and compared using Mantel-Cox and Breslow methods according to the following prognostic factors: brain as the first site of recurrence, pausal state, total radiation dose, stage (TNM), T and N. No significant difference in survival was observed between the cases with brain as the first metastasized organ and the others. The patients were grouped according to the extant prognostic factors: longer total and postirradiation survival rates were observed in patients in premenopausal state (Breslow: p = 0.025 and 0.005) and in the cases treated with total radiation doses greater than 40 Gy (Breslow: p = 0.023 and 0.005). T levels seemed to significantly affect all the examined periods--which influences the stage effect. Conversely, N levels seemed to be of no significant value. The menopausal factor may reflect the effects of age, from which it cannot be separated. These results can be useful for treatment planning.     

Elevated expression and altered pattern of activity of DNA methyltransferase in liver tumors of rats fed methyl-deficient diets

DNA methyltransferase (MTase) activity in nuclear extracts from neoplastic and preneoplastic livers of rats fed a methyl-deficient diet (MDD) is elevated compared with that seen in the livers of control rats. Nuclear proteins were prepared in the presence of protease inhibitors including trans-epoxy succinyl-L-leucylamido-(4- guanido)butane and were fractionated by isoelectric focusing. In normal, control liver, two distinct MTase fractions were observed. In MDD-induced malignant liver, a third fraction, in addition to the previous two, was also seen. Both the DNA substrate and the cytosine site specificities of the third MTase fraction differ from those of the other two fractions. The distinct MTase activity in liver tumor has significantly more de novo MTase activity than do the MTase fractions of normal, control liver. Thus, normal and neoplastic rat livers differ in DNA MTase fractionation patterns and site specificities. The altered DNA MTase activity observed in rat liver tumors caused by MDDs may be one of the critical factors contributing to cancer formation through abnormal DNA methylation.      

眩晕的诊断和治疗

眩晕是由于前庭系统（几乎总是周围性）疾病引起的一种旋转幻觉，任病也方面需要与晕厥的状态、癫痫和惊恐发作相鉴别。持续≥1d的急性孤立性自发性眩晕的单次发作通常由前庭神经炎或小脑梗死所致，两者的鉴别需熟练掌握转头试验（head impulse test）。反复发作性眩晕多见丁良性阵发性位置性眩晕（BPPV）、Meniere病和偏头痛。根据可靠的痫史、位置性试验、听力图和温度试验，一股可以鉴别以上3种疾病。BPPV是最常见的反复发作性眩晕的原因，颗粒复位法通常能够使之立即治愈。后循环缺血极少会导致孤立性眩晕发作，其导致的眩晕是短暂和反复发作的，且病程较短。