Preload recruitable stroke work relationship in the right ventricle: simultaneous assessment using conductance catheter and sonomicrometry

OBJECTIVE: To examine the suitability of the conductance catheter technique for assessment of right ventricular systolic myocardial performance by using preload recruitable stroke work, we compared variables obtained simultaneously by conductance catheter and sonomicrometry dimension techniques. In addition, linearity of volume relationships was studied during rapid preload alteration by bicaval occlusion. DESIGN: Prospective animal study. SETTING: University research laboratory. SUBJECTS: Anesthetized and ventilated swine (n = 9). INTERVENTIONS: Right intraventricular volumes were determined simultaneously by conductance catheter and sonomicrometry by using an ellipsoid shell subtraction model in open-chest swine. Animals were studied at the baseline state and under alterations of afterload, preload, and inotropy. Under each condition, steady-state recordings and transient bicaval occlusions were performed. Agreement of preload recruitable stroke work slope was assessed by using the Bland-Altman analysis, and second-order polynomials were fit to examine volume relationships during bicaval occlusions. MEASUREMENTS AND MAIN RESULTS: At steady state, the relationships for stroke-volumes and end-diastolic volumes were linear between the two methods. Altered physiologic conditions induced by the various interventions produced quantitatively similar changes in preload recruitable stroke work slope within an animal, although absolute values differed in some animals. Regression analysis of the preload recruitable stroke work slope revealed a significant intervention effect independent of the method used. During some bicaval occlusions, nonlinear relationships were observed similarly with both methods. CONCLUSIONS: These results suggest that changes in right ventricular systolic contractility assessed by the preload recruitable stroke work relationship were similar when measured by conductance catheter and sonomicrometry, although absolute values may differ in some animals.     

Invasive and noninvasive pediatric mechanical ventilation

Both invasive and noninvasive mechanical ventilation techniques are inherent to the care of most patients admitted to intensive care units. Despite the everyday use of mechanical ventilation for thousands of patients and the availability of thousands of reports in the medical literature, there are no clear and consistent guidelines for the use of mechanical ventilation for pediatric patients. In many areas data are lacking, and in other areas data are extrapolated from studies performed with adult subjects. Despite the variability in views about mechanical ventilation, 2 themes are consistent. First, modern pediatric respiratory care requires a substantial institutional commitment for state-of-the-art management of the mechanically ventilated patient. Second, a team approach involving physicians, nurses, and respiratory therapists is essential. This review highlights some of the major issues affecting the pediatric patient who requires invasive or noninvasive mechanical ventilation. These issues are pertinent to critical care clinicians because one of the most common reasons for admission to an intensive care unit is the need for mechanical ventilation. Furthermore, the duration of mechanical ventilation is one of the major determinants of the duration and cost of an intensive care unit stay.     

Recent progress in the management of retroperitoneal sarcoma

Retroperitoneal sarcomas (RPS) are rare tumours that typically present late and carry a poor prognosis even following grossly complete resection. In an attempt to improve the outlook for patients with RPS, sarcoma specialists have employed various adjuvant therapies, including extermal beam radiation, intraoperative radiation, brachyradiation and systemic chemotherapy. This article reviews the presentation and prognosis of RPS, and focuses on the results of new treatment strategies compared with conventional management.A Medline search of the English literature was performed to identify all retrospective and prospective reports relating to the management of adult RPS published since 1980. Series that did not analyse RPS separately from other intra-abdominal or extra-abdominal sarcomas or other malignancies were excluded, and information on investigation, presentation, prognostic factors, treatment and outcome was extracted from the remaining reports. Survival and local control data were collected from reports that contained at least 30 cases of RPS (n = 31).While surgical resection remains the cornerstone of treatment for RPS, the majority of patients will relapse and die from sarcoma within 5 years of resection. Adjuvant radiation may improve these results, but further trials are required to definitively demonstrate its benefit. Possible reasons for the failure of conventional treatment are discussed, and alternative strategies designed to overcome these obstacles are presented.     

The role of cytotoxic T-lymphocytes in the prevention and immune surveillance of tumors— lessons from normal and immunodeficient mice

The idea of immunological surveillance against cancer has existed for nearly 100 years but as no conclusive evidence has yet been published the importance of the cellular immune defense in the detection and removal of incipient or existing tumors is still a hotly debated subject. However, in order to select a relevant immunotherapeutic strategy in the treatment of cancer, a fundamental understanding of the basic immunologic conditions under which a tumor develops and exists is a prerequisite. Therefore, a murine model was set up that we hoped would enable us to confirm or reject the theory of immunological surveillance. A large panel of methylcholanthrene induced tumors was established in T-cell immunodeficient nude mice and congenic normal mice to study the influence of the immune system on developing tumors. As nude mice developed tumors fastest and with the highest incidence, we concluded that in this model the immune system constituted a 'tumor-suppressive factor' delaying and sometimes abrogating tumor growth, i.e. performing immune surveillance. Immunogenicity of the tumors was assessed by transplantation back to normal histocompatible mice. Tumors originating from the immunodeficient nude mice turned out to be far more immunogenic than tumors from normal mice, resulting in a high rejection rate. CD8+ cytotoxic T cells were found to be indispensable for this rejection, leading to the conclusion that the cytotoxic T cells perform immune selection in normal mice, eliminating immunogenic tumor cell variants in the incipient tumor. In this review, we discuss the difficulties facing immunotherapy when conclusions are drawn from the presented observations and hypotheses.     

肝动脉注射阿霉素温度敏感脂质体的制剂研究

自Yatvin等创造温度敏感脂质体以来,许多研究结果证明它是靶治疗的良好载体。Chuang等认为根据荷瘤肝脏的血流分布,设想将温度敏感脂质体通过肝动脉注射滞留于肝动脉,结合人为控制释放脂质体中所包封的药物,有可能提高肝脏肿瘤中的药物浓     

An epidemiologic study of adolescent suicide

This study investigated suicides by persons aged ten to nineteen during the years 1978 to 1982 in the City of Montreal. Records of death in the Office of the Coroner, City of Montreal, were examined and suicides designated according to standard criteria. Age, sex, method of suicide, and month of death were noted. Mean incidence of suicide for the entire sample was 5.92 per 100,000 population. The mean figure for males was 9.52 and for females 2.32, with the incidence greater among males in each of the five years. Incidence of suicide in the fifteen to nineteen year old group was approximately ten times that in the ten to fourteen year old group, a difference which was constant across sex and across the five year period. Among boys, hanging was the most frequent method of suicide, with firearms second, and jumping from a height or in front of a vehicle third. Among girls, drug intoxication was most common, with firearms and jumping ranking second and third respectively. No monthly periodicity was found. The epidemiology of adolescent suicide in Montreal appears to be similar to that reported in other locations.     

A study of adaptive responses in cell signaling in migraine and cluster headache: correlations between headache type and changes in gene expression

The project was an investigation into whether changes in the expression of G-proteins underlie altered cell signaling in migraine and cluster headache. The basis for this assumption is that altered physiological responses are seen in migraineurs and that differences in cell signaling are detected biochemically in various cell types isolated from peripheral blood. Levels of three G-protein mRNAs—Gsα, Giα, and Gqα were quantified in lymphocytes from clinically well-defined migraine and cluster headache patients and correlated with headache type and influence of drug treatment. Giα mRNA was reduced by 50% in all migraine patients compared with control subjects; similarly in patients with or without aura, in patients with a migraine headache at the time of sampling, and patients in a quiescent state. No reduction in the levels of Gsα or Gqα mRNA were seen in migraine patients. A smaller reduction was seen in cluster headache patients, most marked in those without medication. Levels of Gsα. mRNA were significantly reduced in cluster headache patients compared with migraine patients. The marked down-regulation of Giα mRNA in migraine, whether quiescent or acute, indicates either an adaptive response to headache in this group of patients or that low levels of Giα mRNA make individuals more susceptible to migraine.     

High-frequency oscillatory ventilation in pediatric respiratory failure: a multicenter experience

OBJECTIVE: The use of high-frequency oscillatory ventilation (HFOV) has increased dramatically in the management of respiratory failure in pediatric patients. We surveyed ten pediatric centers that frequently use high-frequency oscillation to describe current clinical practice and to examine factors related to improved outcomes. DESIGN: Retrospective, observational questionnaire study. SETTING: Ten tertiary care pediatric intensive care units. PATIENTS: Two hundred ninety patients managed with HFOV between January 1997 and June 1998. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients were classified according to presence or absence of preexisting lung disease, symptomatic respiratory syncytial virus infection, or presence of cyanotic heart disease or residual right-to-left intracardiac shunt. In addition, patients for whom HFOV acutely failed were analyzed separately. Those patients with preexisting lung disease were significantly smaller, had a significantly higher incidence of pulmonary infection as the triggering etiology, and had a significantly greater duration of conventional ventilation before institution of HFOV compared with patients without preexisting lung disease. Stepwise logistic regression was used to predict mortality and the occurrence of chronic lung disease in survivors. In patients without preexisting lung disease, the model predicted a 70% probability of death when the oxygenation index (OI) after 24 hrs was 28 in the immunocompromised patients and 64 in the patients without immunocompromise. In the immunocompromised patients, the model predicted a 90% probability of death when the OI after 24 hrs was 58. In survivors without preexisting lung disease, the model predicted a 70% probability of developing chronic lung disease when the OI at 24 hrs was 31 in the patients with sepsis syndrome and 50 in the patients without sepsis syndrome. In the patients with sepsis syndrome, the model predicted a 90% probability of developing chronic lung disease when the OI at 24 hrs was 45. CONCLUSIONS: Given the number of centers involved and the size of the database, we feel that our results broadly reflect current practice in the use of HFOV in pediatric patients. These results may help in deciding which patients are most likely to benefit from aggressive intervention by using extracorporeal techniques and may help identify high-risk populations appropriate for prospective study of innovative modes of supporting gas exchange (e.g., partial liquid breathing or intratracheal pulmonary ventilation).