[SHOCK, COLLAPSE, PROLONGED COLLAPSE, AND SIMILAR STATES. THEORETICAL AND PRACTICAL INTEREST].
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The inflammation of the wrist and carpal collapse play an important role in the deformity of the rheumatoid hand and leads to functional limitation. The aim of this study was to evaluate carpal collapse and related clinical variables in patients with rheumatoid arthritis (RA). Carpal height ratio (CHR) indicating the degree of carpal collapse was measured in 33 female RA patients with a mean age of 41.9+/-10.3 years and 30 female healthy control subjects with a mean age of 40.5+/-9.2 years. The normal range of the carpal collapse was defined in our study population and the incidence of carpal collapse was determined. The correlation between carpal collapse and clinical and laboratory variables including pain by visual analog scale, Ritchie articular index, erythrocyte sedimentation rate, C-reactive protein, health assessment questionnaire indicating functional status, and Larsen roentgenological evaluation were determined. Subgroup analyses were also performed in patients with and without carpal collapse. The mean disease duration of the patients was 12.4+/-5.5 years. The mean CHR index of the patients was significantly lower than in the control group (0.47+/-4.3 and 0.54+/-1.4 respectively). CHR <0.48 was defined as carpal collapse in our study group. Seventeen patients (51.5%) had carpal collapse in the patient group. None of the clinical or laboratory variables except levels of disease duration and Larsen score was correlated with carpal collapse as represented by CHR. The best related clinical variable with carpal collapse was found as duration of disease. The mean duration of disease and the Larsen score were significantly higher in patients with carpal collapse than those without collapse. Other clinical parameters and functional status were similar between patients with and without carpal collapse. In conclusion, although various clinical parameters and functional disability in patients with RA may not be correlated with radiological malalignment, the carpal collapse may be more common in RA than is generally recognized.
UNLABELLED: Hypoxemia is common during anesthesia with one-lung ventilation (OLV). This study tested the hypothesis that selective lobar blockade would result in higher PaO2 values compared with those found with total lung collapse independent of continuous positive airway pressure (CPAP) application. Thirty patients undergoing lobectomy were randomly assigned to one of four groups with the following maneuvers during OLV: Group 1 (n = 8) total lung collapse (TLC) plus 5 cm H2O of CPAP to the nonventilated operative lung for 15 mins, followed by selective lobe collapse plus 5 cm H2O of CPAP (during selective collapse only the surgical lobe was collapsed and the rest of that lung was ventilated); Group 2 (n = 6) selective lobar collapse plus 5 cm H2O of CPAP to the operative lung, followed by TLC plus 5 cm H2O of CPAP; Group 3 (n = 8) total lung collapse without CPAP, followed by selective lobe collapse and no CPAP; Group 4 (n = 8) selective lobe collapse without CPAP, followed by TLC and no CPAP. To obtain selective lobe collapse, the bronchial blocker of the Univent (Vitaid, Lewiston, NY) endotracheal tube was guided into the operative bronchus with the aid of a fiberoptic bronchoscope. Blood pressure, heart rate, and arterial blood gas measurements were obtained during the following times: Time 1--while the patient was awake; Time 2--two-lung ventilation (2LV) in the supine position; Time 3--after 30 min of OLV in the lateral decubitus position (no CPAP or selective blockade); Time 4 and Time 5--during maneuvers described above (see group description); Time 6--2LV resumed; Time 7--30 min after extubation. Twenty-eight patients completed the study. There were no differences among groups with regard to arterial blood pressure, heart rate, or arterial oxygen saturation during the experimental maneuvers. All four groups showed a decrease in PaO2 from 2LV to OLV (P < 0.05). Both with and without CPAP application, oxygenation was improved with selective lobe collapse compared with TLC. When selective lobe collapse with 5 cm H2O of CPAP followed TLC (group 1), PaO2 values increased to values similar to those found for 2LV (PaO2 449 +/- 122 vs 394 +/- 105 mm Hg). This study indicates that by using a bronchial blocker, changing from total lung collapse to selective lobar blockade improves PaO2 during lung surgery. IMPLICATIONS: This study examines how oxygen tension in arterial blood can be higher during one-lung ventilation. The use of a bronchial blocker, which changes a total lung collapse to selective lobar blockade, improves oxygenation during lung surgery.
Collapse of the right ventricle and right and left atria is observed in cardiac tamponade. To assess the diagnostic value of each collapse component in identifying cardiac tamponade, two-dimensional and M-mode echocardiograms were recorded simultaneously with the measurement of intrapericardial pressure in five patients as they underwent pericardiocentesis. Before pericardiocentesis, each patient had evidence of right ventricular and right atrial collapse. In addition, left atrial collapse was observed in four patients. During pericardiocentesis, left atrial collapse initially resolved accompanied by a drop in pressure in the pericardial sac. Continuous drainage of pericardial effusion resulted in significant symptomatic improvement and the cessation of paradoxical pulse at the point of resolution of right ventricular collapse. However, right atrial collapse persisted after resolution of right ventricular collapse, but it was absent when pericardiocentesis was completed. Injection of saline solution with heparin into the pericardial sac for cleansing initially caused right atrial collapse, while right ventricular collapse developed with the appearance of cardiac tamponade. In one patient, the simultaneous recording of right ventricular and intrapericardial pressures and two-dimensional echocardiograms demonstrated that right ventricular collapse occurred early in diastole, when intrapericardial pressure exceeded right ventricular pressure. In conclusion, right ventricular collapse is the most reliable sign of cardiac tamponade. Right atrial collapse occurs in the early stage of cardiac tamponade. Left atrial collapse appears very late in the course of hemodynamic deterioration due to cardiac tamponade.
In previous work we characterized a brain derived collapsing factor that induces the collapse of dorsal root ganglion growth cones in culture (Raper and Kapfhammer, 1990). To determine how the growth cone cytoskeleton is rearranged during collapse, we have compared the distributions of F-actin and microtubules in normal and partially collapsed growth cones. The relative concentration of F-actin as compared to all proteins can be measured in growth cones by rationing the intensity of rhodamine-phalloidin staining of F-actin to the intensity of a general protein stain. The relative concentration of F-actin is decreased by about one half in growth cones exposed to collapsing factor for five minutes, a time at which they are just beginning to collapse. During this period the relative concentration of F-actin in the leading edges of growth cones decreases dramatically while the concentration of F-actin in the centers decreases little. These results suggest that collapse is associated with a net loss of F-actin at the leading edge. The distributions of microtubules in normal and collapsing factor treated growth cones were examined with antibodies to tyrosinated and detyrosinated isoforms of alpha-tubulin. The tyrosinated form is found in newly polymerized microtubules while the detyrosinated form is not. The relative proximal-distal distributions of these isoforms are not altered during collapse, suggesting that rates of microtubule polymerization and depolymerization are not greatly affected by the presence of collapsing factor. An analysis of the distributions of microtubules before and after collapse suggests that microtubules are rearranged, but their polymerization state is unaffected during collapse. These results are consistent with the hypothesis that the brain derived collapsing factor has little effect on microtubule polymerization or depolymerization. Instead it appears to induce a net loss of F-actin at the leading edge of the growth cone.
OBJECTIVE: The high incidence of lower lobe collapse in adult intensive care patients is well described. We aimed to document the incidence and distribution of acute lobar collapse in the pediatric intensive care setting. The influence of anatomical and pathophysiological differences between the adult and pediatric respiratory tract will be considered. DESIGN: Retrospective review of chest radiograph series. SETTING: Tertiary referral center for pediatric intensive care and the Department of Diagnostic Radiology in a large teaching hospital in England. PATIENTS: Cohort of 160 patients receiving intensive care during a 2-yr period (age range, 6 days-18 yrs; median, 23 months). INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Twenty-four of 160 children (15%) developed acute lobar collapse during their intensive care unit admission. Isolated right upper lobe collapse occurred in 14 patients, right upper lobe in association with one or more other lobes in five patients, and lobar collapse other than the right upper lobe in five patients. The development of lobar collapse and, in particular, right upper lobe collapse was associated with a lower median age (no collapse, 26 months; lobar collapse, 8 months; right upper lobe collapse, 4 months). Lobar collapse was significantly associated with the requirement for mechanical ventilation during admission (chi-square, 12.18; p = .005). It was observed in association with both high and low endotracheal tube positions. CONCLUSION: The predominance of upper lobe and, in particular, right upper lobe collapse observed in pediatric intensive care patients contrasts with the high incidence of lower lobe collapse in their adult counterparts. Multiple interrelated factors are likely to be contributory and include the following: a) anatomical and physiological differences between adults and children; b) the pathophysiology of childhood respiratory disease; c) more critical positioning of endotracheal tubes in younger patients and their movement with patient positioning.
STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is characterized by repetitive pharyngeal collapse during sleep. Several techniques have been proposed to assess the collapsibility of the upper airway in awake humans, but sleep-wake comparisons have rarely been attempted and there are few studies comparing OSA patients to control subjects. We sought to compare two collapsibility measurement techniques between normal and apneic subjects, and between wakefulness and sleep. DESIGN: We conducted three studies. First, we examined whether collapsibility assessed by negative pressure pulses (NPPs) during wakefulness reflected values during sleep in 21 normal subjects. Second, we determined in these normal subjects whether collapsibility during sleep assessed by NPPs was predictive of collapsibility measured by inspiratory resistive loading (IRL). Finally, we compared upper-airway collapsibility between apnea patients (n = 22) and normal volunteers (n = 38) during wakefulness by NPPs. SETTING: Clinical and research laboratories at the Brigham and Women's Hospital. PARTICIPANTS: Two populations of normal subjects (n = 21 and n = 38) and OSA patients (n = 22). MEASUREMENTS AND RESULTS: Collapsibility during wakefulness, as measured by NPPs, correlated significantly with collapsibility during sleep (r = 0.62; p = 0.003). There was also a significant correlation between the two measures of collapsibility (IRL and NPP) during sleep (r = 0.53; p = 0.04). Both measures revealed a significant increase in pharyngeal collapsibility during sleep as compared to wakefulness. Finally, apnea patients had significantly greater pharyngeal collapsibility than control subjects during wakefulness (p = 0.017). CONCLUSIONS: These data suggest that upper-airway collapsibility measured during wakefulness does provide useful physiologic information about pharyngeal mechanics during sleep and demonstrates clear differences between individuals with and without sleep apnea.
Size and location of a necrotic lesion are considered important factors predicting collapse of the femoral head in the early stages of osteonecrosis. However, few analytical studies have performed a three-dimensional quantification of lesions to clarify how these two morphological factors are related to the occurrence of collapse. We evaluated the relevance of lesion size and location for prediction of collapse quantitatively using new three-dimensional indexes. Magnetic resonance (MR) imaging was performed in 65 hips in a consecutive series of 47 patients with osteonecrosis without radiological evidence of collapse. Lesion volume as well as latitude and longitude of the center of gravity of the lesion within the femoral head were calculated. Thirty-three hips developed radiological collapse, while in the remaining 32 hips collapse did not occur over 2 years. Multiple logistic regression analysis showed a significant relationship between lesion volume and radiological collapse. In 35 hips in which the lesion volume was less than 30% of the femoral head, only 9 collapsed. In comparison with non-collapsed hips, collapsed hips had a significantly higher combined value for latitude and longitude of the lesion, corresponding to the anterosuperior portion of the femoral head. Quantitative analysis of lesion morphology demonstrated that lesion volume is strongly correlated with risk of collapse, and that lesion location is an important prognostic indicator of collapse in small necrotic lesions.
This paper reports on the experimental characterization of collapse-mode operation of capacitive micromachined ultrasonic transducers (CMUTs). CMUTs are conventionally operated by applying a direct current (DC) bias voltage less than the collapse voltage of the membrane, so that the membrane is deflected toward the bottom electrode. In the conventional regime, there is no contact between the membrane and the substrate; the maximum alternating current (AC) displacement occurs at the center of the membrane. In collapse-mode operation, the DC bias voltage is first increased beyond the collapse voltage, then reduced without releasing the collapsed membrane. In collapse-mode operation, the center of the membrane is always in contact with the substrate. In the case of a circular membrane, the maximum AC displacement occurs along the ring formed between the center and the edge of the membrane. The experimental characterization presented in this paper includes impedance measurements in air, pulse-echo experiments in immersion, and one-way optical displacement measurements in immersion for both conventional and collapse-mode operations. A 205-microm x 205-microm 2-D CMUT array element composed of circular silicon nitride membranes is used in the experiments. In pulse-echo experiments, a custom integrated circuit (IC) comprising a pulse driver, a transmit/receive switch, a wideband low-noise preamplifier, and a line driver is used. By reducing the parasitic capacitance, the use of a custom IC enables pulse-echo measurements at high frequencies with a very small transducer. By comparing frequency response and efficiency of the transducer in conventional and collapse regimes, experimental results show that a collapsed membrane can be used to generate and detect ultrasound more efficiently than a membrane operated in the conventional mode. Furthermore, the center frequency of the collapsed membrane can be changed by varying the applied DC voltage. In this study, the center frequency of a collapsed transducer in immersion is shown to vary from 20 MHz to 28 MHz with applied DC bias; the same transducer operates at 10 MHz in the conventional mode. In conventional mode, the maximum peak-to-peak pressure is 370 kPa on the transducer surface for a 40-ns, 25-V unipolar pulse excitation. In collapse mode, a 25-ns, 25-V unipolar pulse generates 590 kPa pressure at the surface of the transducer.
The aim of this study was to evaluate the clinical outcome of our patients with idiopathic collapsing focal segmental glomerulosclerosis (FSGS) as compared to those with non-collapsing FSGS. The study included a total of 39 patients with idiopathic FSGS. Of these, 11 had collapsing FSGS and the remaining 28 were collectively grouped as non-collapsing FSGS. The mean ages, gender ratio (M:F), and percentage of African-American patients in collapsing versus non-collapsing FSGS groups were 12.7+/-3.1 and 8.9+/-5.1 years, 1.2:1 and 4.6:1, and 90.9 and 53.6%, respectively. After a mean followup period of 31.5+/-22.3 months, 8 patients (73%) with collapsing FSGS had chronic renal impairment as compared to 8 (29%) patients with non-collapsing FSGS group after a mean follow-up period of 18.7+/-12.9 months. However, the cumulated renal survival at 30 months did not reveal a significant difference. In comparison to non-collapsing FSGS, collapsing FSGS in our study was equally common in females as in males and occurred predominantly in African Americans. The outcome of our patients with collapsing FSGS at 30 months was better than in previous reports.
Optimization of the freeze-drying process needs to characterize the physical state of frozen and dried products. A protocol to measure the collapse temperature of complex biological media such as concentrated lactic acid bacteria using freeze-drying microscopy was first elaborated. Afterward, aqueous solutions of one or several components as well as concentrated lactic acid bacterial suspensions were analyzed in order to study how the structure of these materials is degraded during freeze-drying. A similar behavior toward collapse was observed for all aqueous solutions, which was characterized by two temperatures: the "microcollapse" temperature (T(microc), beginning of a local loss of structure) and the "collapse" temperature (T(c), beginning of an overall loss of structure). For aqueous solutions, these two temperatures were close, differing by less than 3 degrees C. Nevertheless, when lactic acid bacteria were added to aqueous solutions, the collapse temperatures increased. Moreover, the interval between microcollapse and collapse temperatures became larger. Lactic acid bacterial cells gave a kind of "robustness" to the freeze-dried product. Finally, comparing glass transition, measured by differential scanning calorimetry (DSC) and collapse temperature for aqueous solutions with noncrystallizable solutes, showed that these values belonged to the same temperature range (differing by less than 5 degrees C). As suggested in the literature, the glass transition temperature can thus be used as a first approximation of the collapse temperature of these media. However, for lactic acid bacterial suspensions, because the difference between collapse and glass transition temperatures was about 10 degrees C, this approximation was not justified. An elegant physical appearance of the dried cakes and an acceptable acidification activity recovery were obtained, when applying operating conditions during freeze-drying in vials that allowed the product temperature to be maintained during primary drying at a level lower than the collapse temperature of lactic acid bacterial suspensions. Consequently, the collapse temperature T(c) was proposed as the maximal product temperature preserving the structure from macroscopic collapse and an acceptable biological activity of cells.
STUDY DESIGN: The associations between vertebral body collapse and the size or location of the metastatic lesions were analyzed statistically to estimate the critical point of collapse. OBJECTIVES: To determine risk factors for collapse, to estimate the predicted probability of collapse under various states of metastatic vertebral involvement, and to establish the criteria of impending collapse. SUMMARY OF BACKGROUND DATA: Pathologic vertebral collapse brings about severe pain and paralysis in patients with cancer. Prevention of collapse plays a significant role in maintaining or improving their quality of life. Because no previous study has clarified the critical point of vertebral collapse, however, the optimum timing for prophylactic treatment has been unclear. METHODS: The size and location of metastatic tumor from Th1 to L5 were evaluated radiologically for 100 thoracic and lumbar vertebrae with osteolytic lesions. The correlations between collapse and the following risk factors (x1-x4) were determined by means of a multivariate logistic regression model: x1, tumor size (the percentage of tumor occupancy in the vertebral body [% TO]); x2, pedicle destruction, x3, posterior element destruction; and x4, costovertebral joint destruction. RESULTS: Significant risk factors were costovertebral joint destruction (odds ratio, 10.17; P = 0.021) and tumor size (odds ratio of every 10% increment in %TO, 2.44; P = 0.032) in the thoracic region (Th1-Th10), whereas, tumor size (odds ratio of every 10% increment in %TO, 4.35; P = 0.002) and pedicle destruction (odds ratio, 297.08; P = 0.009) were main factors in the thoracolumbar and lumbar spine (Th10-L5). The criteria of impending collapse were: 50-60% involvement of the vertebral body with no destruction of other structures, or 25-30% involvement with costovertebral joint destruction in the thoracic spine; and 35-40% involvement of vertebral body, or 20-25% involvement with posterior elements destruction in thoracolumbar and lumbar spine. CONCLUSIONS: With respect to the timing and occurrence of vertebral collapse, there is a distinct discrepancy between the thoracic and thoracolumbar or lumbar spine. When a prophylactic treatment is required, the optimum timing and method of treatment should be selected according to the level and extent of the metastatic vertebral involvement.
BACKGROUND: Cardiac tamponade after cardiac surgical procedures is often associated with hemodynamically significant localized pericardial effusions. The localized collection of pericardial effusion in the postoperative period and the atypical presentation of cardiac tamponade limit the use of conventional clinical and echocardiographic signs usually seen with a circumferential pericardial effusion. Observation of left ventricular diastolic collapse in the echocardiogram of a patient with postoperative regional cardiac tamponade prompted us to explore the frequency of this sign in regional cardiac tamponade. METHODS AND RESULTS: We retrospectively analyzed the echocardiograms of 18 patients with postoperative cardiac tamponade for the following echocardiographic findings: right atrial collapse, right ventricular diastolic collapse, left atrial collapse, and left ventricular diastolic collapse. Three of the 18 patients had circumferential pericardial effusion, and 15 had loculated pericardial effusion; in 10, the effusion was predominantly posterior, and in the other five, it extended laterally or inferiorly. The conventional echocardiographic signs of cardiac tamponade such as right atrial collapse, right ventricular diastolic collapse, and left atrial collapse were present in only 3, 1, and 3 of these 15 patients, respectively, but all exhibited left ventricular diastolic collapse. Increasing pressure within the compartment of a loculated pericardial effusion reaching the limit of pericardial distensibility and consequent transient reversal of transmural left ventricular pressure during diastole are most likely the basis for diastolic collapse of the thick-walled ventricle in a setting of regional cardiac tamponade. CONCLUSIONS: We conclude that left ventricular diastolic collapse is a frequent sign of regional cardiac tamponade and could be a useful marker of tamponade in postoperative patients.
Podocytes are well-differentiated postmitotic cells whose function is largely based on their complex cytoskeletal architecture. In diseases with proteinuria, podocytes undergo morphologic changes. Podocytes react to an injurious stimulus by a reorganization of their foot process architecture that is independent of the primary injury and the cause of the proteinuria. Collapsing glomerulopathies, including the idiopathic and secondary forms due to HIV infection, have been previously considered a part of the focal sclerosing glomerulosclerosis (FSGS) spectrum. However, in contrast to FSGS, both forms of collapsing glomerulopathy are characterized by segmental and global collapse of the glomerular basement membrane (GBM) and by characteristic ultrastructural alterations in podocytes. These alterations include loss of the actin-based cytoskeleton, a dysregulated/dedifferentiated phenotype, cellular hypertrophy, and cell proliferation. These observations raise the following questions: 1) What mechanism causes glomerular collapse and do podocytes have a role? We recently proposed that in collapsing glomerulopathies the composition of the GBM is altered and contains more immature forms of collagen IV. These observations suggest that dedifferentiated/dysregulated podocytes may participate in remodeling the GBM composition, producing fetal collagen isoforms. 2) What is the pathomechanism underlying podocyte dysregulation? Although it is still unclear which etiologic factors are responsible for the idiopathic forms of collapsing glomerulopathy, in situ hybridization studies in a transgenic mouse model of HIV-associated collapsing glomerulopathy and on renal biopsies of patients with HIV-associated collapsing glomerulopathy demonstrated the presence of the HIV-1 RNA in podocytes and tubular epithelial cells. These findings suggest a direct link between viral gene expression and the dysregulation of the podocyte phenotype. 3) Another open question is how podocytes become infected in HIV-associated collapsing glomerulopathy. HIV-1 typically uses CD4 and a co-receptor such as CCR5 or CXCR4 to enter cells. So far, there is no demonstration of the expression of these receptors in podocytes. These negative findings, however, do not exclude the possibility that in the kidney another, CD4 independent, co-receptor may be used for viral cell entry. Finally, is it important to mention that collapsing glomerulopathies have a high prevalence in black patients, suggesting a link between racial background and the virus-related podocyte injury.
Thirty-five patients (54 hips) with osteonecrosis of the femoral head without collapse or only with a crescent sign were followed up for at least 5 years to clarify the natural course of osteonecrosis. During the followup, 28 hips (52%) in 21 patients collapsed including nine hips in nine patients with small necrotic lesions occupying less than the medial (2/3) of the weightbearing area. Cessation of collapse then was observed in 15 (14 patients) of the 28 hips (54%), especially in eight of the nine hips (89%) with small necrotic lesions. Of the 15 hips in 14 patients with cessation of collapse, 11 hips (73%) in 11 patients had less than 2 mm collapse and 10 hips in nine patients became asymptomatic. The analysis indicated that collapse of the femoral head does not necessarily determine a poor prognosis, and even after collapse occurs, subsequent cessation of collapse can be expected in a certain percentage of hips. Hips with less than 2 mm collapse and necrotic lesions occupying less than the medial (2/3) of the weightbearing area have a high chance of cessation of collapse and improvement of symptoms with no surgical intervention.