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Since the early 1900s, surgical interruption of the inferior vena cava (IVC) has been utilized in the management of venous thromboembolism (VTE). With the advent of newer-generation percutaneous devices in the late 1970s, their use and indications have expanded. The literature to support their efficacy, however, is limited to several case series and a single randomized controlled trial. Despite this, some have advocated the use of IVC filters as primary treatment of VTE in certain patient populations. In addition, there has been a large amount of interest in their use as prophylaxis against pulmonary embolism (PE) in high-risk patients. In the past 10 years, we have also seen the development and initial use of temporary devices, although their role in the management of this disease is even less certain. This article will review the recent literature on efficacy, complications, and indications for the use of IVC filters in the prevention and treatment of PE.

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Alveolar hemorrhage occurs as a complication of systemic inflammatory diseases. In addition to alveolar hemorrhage, patients with systemic sclerosis (SSc) may suffer from digital infarction, pulmonary hypertension, and renal crisis. Although a common pathogenesis of this disease that explains the variety of problems during a patient's illness has yet to be identified, the unique characteristics of SSc may alter our approach to alveolar hemorrhage in this patient population. We describe a patient with SSc, who presented with pulmonary hypertension and alveolar hemorrhage complicated by features suggesting re-occurrence of scleroderma renal crisis. Our successful management of this patient, with complications that are usually of high morbidity, may be attributed to our judicious use of glucocorticosteroid therapy and maximization of angiotensin-converting enzyme inhibition. In view of the potential for glucocorticoids to precipitate scleroderma renal crisis, we suggest caution in the use of these medications for manifestations that may be similar in their pathogenesis.

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Postoperative pulmonary complications (PPC) lead to significant morbidity after both thoracic and non-thoracic surgical procedures. The role of smoking as an independent risk factor is controversial, though recent level III and IV studies suggest that it may indeed be significant. In addition, the role and timing of pre-operative smoking cessation is not clear. Although some studies suggest that abstinence too soon prior to operation may actually increase the risk of PPC, it still appears that aggressive counseling for smoking cessation prior to any elective procedure is the best overall course of action.

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Engraftment syndrome (ES) is a toxicity of autologous stem cell transplantation that occurs unexpectedly and is occasionally fatal. This syndrome, manifested as fever, rash and pulmonary deterioration which becomes evident at marrow engraftment, has been described by several centers but as yet remains enigmatic. We describe this syndrome at a single institution and note that it has accompanied the transition from the use of autologous marrow rescue to peripheral blood stem cell rescue. In this study, the occurrence of ES is related to the mononuclear cell dose at reinfusion. We found, in agreement with other reports, that patients developing ES are predominantly women undergoing therapy for solid tumors who demonstrate neutrophil engraftment at a significantly greater rate than do those patients not expressing the syndrome. We did not note a significant relationship between growth factor use (G-CSF) or amphotericin B exposure and the syndrome, as has been previously reported. The progenitor cell populations obtained with autologous marrow and peripheral blood stem cells are different. We hypothesize that the interaction of committed myeloid precursors from the stem cell product with the pulmonary vascular endothelium can be deleterious, especially under the influence of the inflammatory cytokines present at the time of engraftment.

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BACKGROUND: Survival rates from mechanical ventilation (MV) in allogeneic bone marrow transplantation are poor, but little is known about the need for and outcomes from MV in patients who undergo autologous hematopoietic stem cell transplantation (AHSCT). STUDY OBJECTIVE: To determine the frequency of and risk factors for the use of MV in recipients of AHSCT and to identify predictors of survival in mechanically ventilated AHSCT patients. DESIGN: Retrospective, cohort analysis SETTING: Tertiary-care, university-affiliated medical center. PATIENTS: One hundred fifty-nine consecutive patients who underwent AHSCT. INTERVENTIONS: Patient surveillance and data collection. MEASUREMENTS AND RESULTS: The primary outcome measure was the need for MV, and the secondary end point was survival after MV. Of 159 patients, 17 required MV (10. 7%). Three variables were associated with the need for MV: increasing age, use of total body irradiation in the conditioning regimen, and treatment with amphotericin B. As a screening test to predict the need for MV, no risk factor had a sensitivity or specificity > 82%. Three of the 17 mechanically ventilated patients (17.6%) survived to discharge. Only the mean APACHE (acute physiology and chronic health evaluation) II score separated survivors from nonsurvivors (21.7 vs 31.4; p = 0.029). Both the duration of MV and the length of stay in the ICU were similar in survivors and nonsurvivors. CONCLUSIONS: We conclude that MV is infrequently needed following AHSCT. Although survival after MV in these patients is limited, clinical variables do not reliably allow clinicians to prospectively identify patients destined to die.

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OBJECTIVES: Nonrebreather face masks (NRM) are frequently used in patients with respiratory distress and profound hypoxemia. A simpler modification to the partial rebreather face mask, using only two pieces of respiratory tubing or "tusks," has also been shown to increase FiO2 compared with the NRM in five normal subjects. Clinically, we have observed this modification to further increase PaO2 in critically ill patients already using the NRM in the intensive care unit. This study was designed to compare the Tusk mask with the NRM in both a larger group of normal subjects and in patients with underlying lung disease. DESIGN: Prospective, randomized, crossover study. SETTING: A university teaching hospital and tertiary care referral center. SUBJECTS: Sixteen normal subjects (11 male and 5 female; age 30.4+/-6.8 [SD] yrs) and seven patients with interstitial lung disease (ILD) (3 male and 4 female; age 68.1+/-11.9 yrs). INTERVENTIONS: Subjects and patients served as their own controls and were randomized to wear either the NRM or Tusk mask for a 30-min period. After a 60-min washout period, the other mask was applied. MEASUREMENTS AND MAIN RESULTS: Arterial blood gas measurements were performed immediately before and at the end of each 30-min test period. Respiratory synchronization during the study period was achieved, using a metronome. In the normal subjects, PaO2 using the NRM and Tusk masks increased 290.0+/-57.1 torr (38.6+/-7.6 kPa) and 330.0+/-68.9 torr (44.0 +/-9.2 kPa), respectively (p=.032). PaO2 increased 293.4+/-38.0 torr (39.1+/-5.1 kPa) with the NRM and 378.4+/-61.7 torr (50.4+/-8.2 kPa) with the tusk mask (p=.001) in the patients with ILD. There was no statistically significant change seen in mean PaCO2 with either mask in either group. The mean PaO2 returned to within 6% of baseline in both groups after the washout period. CONCLUSIONS: Both normal subjects and patients with compromised pulmonary function achieved a higher PaO2 using a Tusk mask than when using the conventional NRM, at the same oxygen flow rate. Patients with hypoxemia may obtain lifesaving benefit from the additional concentration of oxygen delivered via the Tusk mask.

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Pulmonary tumor embolism is a rare but well-documented cause of respiratory failure in patients with cancer. This entity is probably clinically underrecognized and may represent an important cause of morbidity and mortality. A typical pattern of multiple peripheral subsegmental defects on perfusion lung scanning has been described. We present a case of a unilateral near absence of perfusion in a 53-year-old woman who on autopsy was found to have diffuse tumor microembolism. As new chemotherapeutic agents are developed for the treatment of malignancies, an early diagnosis may become more important. A high-probability perfusion scan should not dissuade the clinician from pursuing further evaluation. Cytologic findings of pulmonary venous blood may be diagnostic.

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STUDY OBJECTIVES: We sought to compare arterial oxygen partial pressure (PaO2) relationships between a 15.1% hypoxia inhalation test (HIT) at sea level and a hypobaric chamber exposure equivalent to 2,438 m (8,000 feet) of altitude above sea level in patients with chronic obstructive pulmonary disease (COPD) and healthy subjects. DESIGN: Comparison of physiologic variables before and during intervention. SETTING: A referral-based pulmonary disease clinic at a US Army medical center in a metropolitan area. SUBJECTS: The study included three groups: group 1, 15 patients, 3 women and 12 men, with COPD (forced expiratory volume in the first second [FEV1, mean +/- SD], 41 +/- 14% of predicted); group 2, 9 healthy men; and group 3, 18 men with COPD (FEV1, 31 +/- 10% of predicted) previously reported in detail. INTERVENTIONS: We evaluated each group at sea level followed by one of two different types of hypoxic exposures. Group 1 received exposure to 15.1% oxygen at sea level, the HIT. Groups 2 and 3 received hypobaric chamber exposure equivalent to 2,438 m (8,000 feet) above sea level. MEASUREMENTS AND MAIN RESULTS: For all three groups combined, the arterial oxygen tension at sea level (PaO2SL) explained significant variability in PaO2 during hypoxic exposure according to the following formula: PaO2 during exposure = 0.417 (PaO2SL)] + 17.802 (n = 42; r = 0.756; p < 0.001). Neither the type of hypoxic exposure (HIT vs hypobaric), status as patient vs control, sex, nor age explained significant variability in PaO2 during hypoxia exposure after inclusion of PaO2SL as a covariate in analysis of variance. Subsequent analysis revealed that forced expiratory spirometric variables FEV1 and FEV1 to FVC ratio served as second order covariates with PaO2SL to improve description of PaO2 during hypoxia exposure for the combined samples (n = 42; p < 0.05). Analysis of residuals from regression analysis revealed approximately normal distribution. CONCLUSIONS: The PaO2 relationships did not differ between the 15.1% HIT at sea level and hypobaric exposures of 2,438 m (8,000 feet) above sea level. Normal subjects and patients with COPD formed a single relationship. The present study extends descriptive models to a larger range of subjects. Regression models have definable accuracy in predicting PaO2 during hypoxia exposure that increases with inclusion of spirometric variables.

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