A purpose-design computational method for estimation of plane of maximum curvature in Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional (3D) deformity, and the plane of maximum curvature (PMC) is proposed to reflect these clinical features, which refers to a vertical plane presenting the maximum projected spinal curvature and its parameters include the PMC Cobb and orientation (angle between PMC and sagittal planes). This study aimed to develop a computational method (CM) for PMC estimation. Twenty-nine patients with AIS and computed tomography (CT) images were recruited. For CT, PMC was determined by rotating a vertical plane about its vertical axis with 5° increment until the maximum Cobb angle was measured. For CM, PMC was estimated via identifying the eight points (the corner points of the superior and inferior endplates of the upper and lower end-vertebrae respectively) in the coronal and lateral CT images. Two experienced raters repeated the PMC estimation three times with one-week interval. The intra-class correlation coefficient (ICC) and Bland-Altman method were used for statistical analysis. Twenty-seven right thoracic curves (RTs) (mean Cobb: 46.1°±12.4°) and 23 left thoracolumbar/lumbar (LTLs/LLs) (mean Cobb: 30.6°±11.1°) were analysed. The intra- and inter-rater ICC values were >0.91 and 0.84 in RTs and LTLs/LLs, respectively. The PMCs obtained from the CM and CT were showed good agreement was also observed between the PMCs obtained from the two methods according to ICC (>0.90) and Bland-Altman method assessments. This purpose-design computational method could provide reliable and valid estimation of PMCs for AIS, which has potential to be used as an alternative for 3D assessment.

Assessment of the plane of maximum curvature for patients with adolescent idiopathic scoliosis via computed tomography

BACKGROUND

In the assessment of three-dimensional features of adolescent idiopathic scoliosis, the plane of maximum curvature was compared with the coronal Cobb angle.

OBJECTIVES

To investigate the intrarater reliability, variability, and difference of the prone plane of maximum curvature measurements taken from computed tomography using the constrained and unconstrained Cobb methods; to assess the difference and correlation between the prone plane of maximum curvature measurements obtained using the constrained and unconstrained Cobb methods; and to examine differences and correlation between the prone plane of maximum curvature Cobb angle and coronal Cobb angle measurements.

STUDY DESIGN

Retrospective study.

METHODS

Records of 29 subjects with adolescent idiopathic scoliosis aged 15.8 ± 3.5 years were reviewed (25 thoracic and 24 thoracolumbar/lumbar curves). An experienced rater measured the plane of maximum curvature using the constrained and unconstrained Cobb methods, and the coronal Cobb angles using the conventional Cobb method on computed tomography images 3 times each with 1-week interval. The intraclass correlation coefficient (2,1), Pearson correlation coefficient (r), one-way repeated measures analysis of variance, and paired t test were applied for various analyses.

RESULTS

The intraclass correlation coefficients for all intrarater reliability assessments were greater than 0.87. The plane of maximum curvature measurements of the two Cobb methods were excellently correlated (r ⩾ 0.97) with no significant difference (P > 0.05). The mean plane of maximum curvature Cobb angle was moderately correlated with (r > 0.72) but significantly greater (P < 0.001) than the mean coronal Cobb angle.

CONCLUSION

The plane of maximum curvature measurements obtained from computed tomography were found to be reliable while the plane of maximum curvature measurements of the two Cobb methods were comparable. The mean plane of maximum curvature Cobb angle was moderately correlated with but significantly greater than the mean coronal Cobb angle.

CLINICAL RELEVANCE

The plane of maximum curvature measurements taken from computed tomography was found to be reliable, hence it could be used as a supplement to the coronal Cobb angle in the assessment and management of adolescent idiopathic scoliosis. With technological advancement, the radiation dose of computed tomography can be further reduced to a safer level for a broader range of cases.

Estimation of plane of maximum curvature for the patients with adolescent idiopathic scoliosis via a purpose-design computational method

PURPOSE

The coronal Cobb angle is commonly used for assessing the adolescent idiopathic scoliosis (AIS); however, it may underestimate the severity of AIS while the plane of maximum curvature (PMC) could be a promising descriptor for three-dimensional assessment of AIS. This study aimed to develop a computational method (CM) for estimating the PMC based on the coronal and sagittal images of the spine, and to verify the results with computed tomography (CT).

METHODS

Twenty-eight thoracic and 24 lumbar curves from 30 subjects with AIS were analysed. For the CM, PMC was estimated via identifying the two corner points at the superior endplate of upper-end vertebra and the inferior endplate of lower-end vertebra in the coronal and sagittal CT images separately (eight corner points in total). For the CT, PMC was determined through rotating the spine images axially until the maximum Cobb angle was found. Intraclass correlation coefficient (ICC), Bland-Altman method and linear regression analysis were used for the statistical analyses.

RESULTS

The high ICC values (intra- > 0.91; inter- > 0.84) suggested very good intra- and inter-rater reliability of the CM in PMC estimation. The high ICC values (> 0.91) and assessment of Bland-Altman method demonstrated a good agreement between the PMC acquired using the CM and CT. The generated linear regression equations (R² > 0.69) could allow to estimate the PMC (originally measured through the CT) via the CM.

CONCLUSION

The developed computational method could estimate reliable and valid PMC for the patients with AIS, and become feasible for three-dimensional assessment of AIS.

LEVEL OF EVIDENCE

III.

[Effect of intervention programs regarding community "5+1" staged diabetes target management on patients with type 2 diabetes mellitus]

Objective: To analyze the effect of intervention programs and influencing factors regarding the community "5+1" staged diabetes target management on patients with type 2 diabetes mellitus (T2DM) and to provide evidence for improving the quality of life (QOL). Methods: A total of 12 community health service centers from Shanxi province, Jiangsu province, and Ningxia Hui autonomous region were selected as intervention group and control group, by stratified cluster sampling method. "5+1" model was used in intervention groups and basic public health services model was applied in control groups for this two-year follow-up. Data was collected through a questionnaire on demographic and disease-related information, while the QOL was measured with SF-36. Multiple linear regression and conducted by SAS 9.4. Results: A total of 2 467 subjects were included at baseline and 1 924 had completed a two-year-long management service. After intervention programs being implemented, the net effect of PCS score between the intervention and the control groups was 13.6, with the net effect of MCS score as 29.8. Results from the multiple linear regression showed that the main factors affecting PCS scores included age, type of medical insurance, baseline PCS score and regions of residency. Main factors related to MCS score included age, type of medical insurance, baseline MCS score, hypertension, and region of residency. Conclusion: Community "5+1" staged diabetes target management model presented favorable effect of improving the QOL on T2DM patients.

[A clinical analysis of insulin antibody in type 2 diabetic patients]

This study was conducted to evaluate the relationship between serum insulin levels and the production of insulin antibody (IA) in type 2 diabetes (T2DM). A total of 647 T2DM were included. Among them, 20.9% patients were IA positive, who were elder and had a longer duration, lower BMI, a higher positive rate of glutamic acid decarboxylase antibody(GADAb) and higher serum insulin levels during an insulin secretion test. More patients were treated with insulin in IA positive group than in IA negative group (65.9% vs 41.0%, P=0.000). Fasting serum insulin level was associated with occurrence of IA in all patients (OR=1.02, P=0.001) and insulin treated patients (OR=1.033, P=0.002). The cut-off point of fasting serum insulin level for predicting IA positive was 17.87 mIU/L (sensitivity 55.1%, specificity 89.0%). Exogenous insulin use is associated with the presence of IA. Fasting serum insulin level can be used as a predictor for the production of IA in insulin-treated patients.

Factors associated with adherence to low-tidal volume strategy for acute lung injury and acute respiratory distress syndrome and their impacts on outcomes: an observational study and propensity analysis

BACKGROUND

The purpose of this study was to investigate the factors affecting adherence to the low-tidal volume (LTV) strategy in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) and their impacts on outcomes.

METHODS

This prospective observational study included 111 patients with ALI/ARDS admitted to six intensive care units between March 2010 and February 2011. The patients were divided into the LTV group, which received a TV ≤7.5 mL/kg predicted body weight (PBW), and the non-LTV group, which received a TV >7.5 mL/kg PBW. We studied the association of selected clinical factors and adherence to the LTV strategy, and evaluated their impacts on 28-day mortality and 1-year mortality by the propensity-match process.

RESULTS

Adherence to the LTV strategy was only 44%, which was related to lung injury severity (odds ratio [OR]: 3.15, P=0.038), muscle relaxant use (OR: 3.28, P=0.031), and depth of sedation (OR: 0.65, P=0.008). Propensity score-based analysis showed that the LTV group had modestly better 28-day survival (P=0.081) and 1-year survival (P=0.067) than the non-LTV group. Moreover, muscle relaxant use was strongly associated with reducing the risk of death at both 28 days (hazard ratio [HR]: 0.122, 95% confidence interval [CI]: 0.027-0.542, P=0.006) and 1 year ([HR]: 0.111, 95% [CI]: 0.030-0.408, P=0.001).

CONCLUSION

Adherence to the LTV strategy was strongly associated with the lung injury score, muscle relaxant use, and depth of sedation. Propensity score-based analysis showed that the use of LTV ventilation and muscle relaxants reduced 28-day and 1-year mortality in ALI/ARDS patients.

Comparison of physiological responses to spontaneous breathing trials with a T-tube and low-level pressure support

Previous studies have shown that spontaneous breathing trials (SBT) with a T-tube or low-level pressure support are comparable. However, low-level pressure support may overestimate the ability of a patient to sustain spontaneous breathing, resulting in premature extubation. Understanding factors contributing to different responses by patients to the two SBT methods aids in clarifying the limitation of using low-level pressure support for SBT. We performed a prospective observational study in 80 consecutive adult patients with mechanical ventilation to identify the factors contributing to different responses of a patient to the two SBT methods. The 80 patients underwent both a T-tube trial and pressure support ventilation of 6 cmH2O (PS-6) on the day of extubation. Stratified analysis was used to evaluate the effects of age, respiratory compliance and resistance, PaO2/FiO2 ratio and underlying disease on post-SBT responses. Comparing the responses to a T-tube trial and PS-6, the patients with old age, poor pulmonary compliance (≤40 ml/cmH2O) and chronic obstructive pulmonary disease had a higher heart rate (difference [95% CI]: 4 [0,8], 5 [2,9], 5 [0,10] beats/minute, respectively) and systolic blood pressure (10 [4,16], 11 [5,16], 7 [0,13] mmHg, respectively) after the T-tube trial. In conclusion, this research shows that old age and impaired respiratory mechanics contribute to different responses to spontaneous breathing trials with a T-tube and low-level pressure support. Further studies are needed to compare the effectiveness of the two SBT methods in predicting successful extubation in such patient groups.

A longitudinal study of the effects of long-term exposure to lead among lead battery factory workers in Taiwan (1989-1999)

The objective of this study was to assess the relationship between blood-lead levels (BLL), hematological, liver and renal indicators among workers in a lead battery factory in Taiwan over a 10-year period. Blood samples were taken periodically from 30 workers and BLL, HGB (hemoglobin), RBC (red blood cells), WBC (white blood cells) and HCT (hematocrit) were measured. Levels of GPT (alanine aminotransferase) and Crea (creatinine) in the blood were assessed to indicate liver and renal function, respectively. The results showed that there was a general decrease in BLL over the 10-year period (except for 1993). There was a similar trend for HCT, RBC and Crea. There was no significant trend for the other health indicators. Four generalized estimating equation (GEE) models [correlation model (A), threshold correlation model (B), instant change model (C) and lag change model (D)] were set up to demonstrate the causal relationship between BLL and the other health indicators. Models A and C showed that BLL correlated positively with RBC, but negatively with Crea. Model B showed that BLL correlated positively with GPT. There were no significant correlations of BLL with the other indicators. Models C and D, (GEE with logit link function to analyze the association between changes BLL and the other health indicators) showed that when BLL increased, RBC and HCT increased, both longitudinally and cross-sectionally. The authors conclude that long-term exposure to lead stimulates production of RBC and HCT, but the effect on liver and renal function was unclear.

Removal of cardiac beat artifact in esophageal pressure measurement via a modified adaptive noise cancellation scheme

Information on volume-pressure relationships of human lungs is usually based on indirect determination of intrapleural pressure (P(ip)) obtained from the esophagus. Unfortunately, cardiac beat artifact frequently corrupts measurement of esophageal pressure (P(es)). In this study, we presented a modified adaptive noise cancellation (MANC) scheme for removing the cardiac beat artifact in the P(es) signal. The proposed methodology used an airflow signal as the reference signal with least-mean-square method as the adaptive algorithm. The results of six experiments on two Brown-Norway rats showed a significant reduction of the apparent cardiac pulsation with minimal distortion of the P(es) signal. The MANC filter also showed evidence of peak suppression at integer multiples of heart rate in the fast Fourier transform of the P(es) signal while leaving the remaining spectrum largely unperturbed. A t-test method and the ratio of standard deviation to mean (std/mean) statistics of airway resistance (R(aw)) values were used to evaluate the performance of the MANC filter. In all six experiments, a reduction of std/mean of R(aw) by 12.5%-68% was obtained, indicating the effectiveness of the proposed scheme.

US-guided transthoracic cutting biopsy for peripheral thoracic lesions less than 3 cm in diameter

PURPOSE

To evaluate the safety and accuracy of ultrasonography (US)-guided transthoracic cutting biopsy for diagnosing peripheral thoracic lesions (<3 cm).

MATERIALS AND METHODS

Fifty consecutive patients with peripheral thoracic lesions less than 3 cm in diameter underwent US-guided percutaneous transthoracic cutting biopsy with a modified technique. Fifty lesions (43 parenchymal lung, two pleural, two chest wall, and three anterior mediastinal lesions) were sampled for biopsy. The final diagnosis was based on histopathologic analysis of surgical specimens (n = 18) or clinical follow-up (n = 32).

RESULTS

The histology recovery rate was 98% (49 lesions), and the correct diagnosis was obtained in 48 lesions (96%). Twenty-four (48%) lesions were malignant, and 26 (52%) were benign. The diagnostic accuracy for malignant lesions was 92% (22 of 24 lesions). A specific benign diagnosis was made in 17 (65%) of the 26 benign lesions, and the negative predictive value for malignancy was 93% (26 of 28 lesions). Only two patients (4%) developed postbiopsy pneumothorax, and three (6%) developed postbiopsy hemoptysis. Biopsy helped prevent surgery or thoracoscopy in 32 patients (64%): 18 patients with benign disease and 14 with multiple metastases or inoperable cancer.

CONCLUSION

US-guided transthoracic cutting biopsy appears to be a safe and effective method for diagnosing peripheral thoracic lesions less than 3 cm in diameter. The high diagnostic accuracy for benign lesions and metastatic lung cancer can help prevent surgery in many cases.

Acute elevations of plasma asymmetric dimethylarginine and impaired endothelial function in response to a high-fat meal in patients with type 2 diabetes

Asymmetric dimethylarginine (ADMA), a compound detectable in human plasma, is an endogenous inhibitor of NO synthase. Endothelial dysfunction is an early event in atherogenesis, and large-vessel atherosclerosis is a major cause of morbidity and mortality in patients with type 2 diabetes mellitus. Fifty patients with type 2 diabetes mellitus were studied at baseline and 5 hours after ingestion of a high-fat meal. Plasma ADMA measured by using high-performance liquid chromatography increased from 1.04+/-0.99 to 2.51+/-2.27 micromol/L (P:<0.0005). Brachial arterial vasodilation after reactive hyperemia, a NO-dependent function, measured by high-resolution ultrasound, decreased from 6.9+/-3.9% at baseline to 1.3+/-4.5% (P:<0.0001). These changes occurred in association with increased plasma levels of triglycerides and very low density lipoprotein triglycerides, with reduced low density lipoprotein cholesterol and high density lipoprotein cholesterol, and with no changes in total cholesterol. The increase in plasma ADMA in response to a high-fat meal was significantly and inversely related to the decrease in percent vasodilation. In 10 of the subjects studied with a similar protocol on another day, no significant changes in the brachial artery flow responses or in plasma ADMA were observed 5 hours after ingestion of a nonfat isocaloric meal. The data suggest that ADMA may contribute to abnormal blood flow responses and to atherogenesis in type 2 diabetics.

Clinical spectrum of acute respiratory distress syndrome in a tertiary referral hospital: etiology, severity, clinical course, and hospital outcome

BACKGROUND AND PURPOSE

The clinical picture of patients with acute respiratory distress syndrome (ARDS) in Taiwan has seldom been reported, although new definitions of ARDS have been introduced over the past years. The purpose of this study was to investigate the clinical characteristics, modalities of management, and outcomes in patients with ARDS treated in a tertiary referral hospital.

METHODS

Case records were selected through a computerized search of diagnosis codified at discharge during the period from January 1995 to June 1997. Patients who met the criteria of the American-European Consensus Conference definition of ARDS were included and their medical records were retrospectively reviewed.

RESULTS

A total of 145 patients (91 men, 54 women; mean age, 58 years) who fulfilled the criteria for ARDS were identified. Malignancy (n = 53) and diabetes mellitus (n = 23) were the most common co-morbid conditions. Pneumonia (n = 90), including community-acquired pneumonia in 45 (31%) patients, was the most common risk factor. The lung injury score at the time of ARDS diagnosis was 2.89 +/- 0.40 (mean +/- standard error, SE). The worst value of PaO2/FIO2 was 86.8 +/- 3.8 mm Hg (mean +/- SE). Among the 145 patients, 130 (90%) received mechanical ventilation and 118 (81%) were treated in the intensive care unit. In-hospital mortality was 87%. Seventy (48%) patients received intensive treatment for ARDS, among whom 52 (74%) died; the most common causes of death were multiple organ failure (54%) and respiratory failure (23%).

CONCLUSIONS

The mortality in patients with ARDS was high in this tertiary referral institution. Our findings suggest that aggressive ventilatory, pharmacologic, and supportive therapy may be important to achieve a higher survival rate.

Assessment of endothelium-mediated vasodilation of the peripheral circulation by transcutaneous ultrasonography and venous occlusion plethysmography

Transcutaneous ultrasonography is a non-invasive technique with the ability to measure the volumetric blood flow of the peripheral circulation. Peripheral blood flow can be determined by high-resolution imaging of vessel diameter coupled with Doppler assessment of flow velocity. This method, however, has not been validated in vivo. Accordingly, brachial artery flow in response to intraarterial infusion of vasodilators was assessed by ultrasonography in 16 healthy subjects and compared to values obtained simultaneously by venous occlusion plethysmography. Blood flow calculated from ultrasound-derived vessel diameter and flow velocity was found to highly correlate with plethysmographic flow, with r values ranging from 0.83 to 0.99. Using this ultrasound technique combined with plethysmography, the response of conduit and resistance vessels to endothelium-mediated vasodilation was characterized. Doppler velocity rose dramatically with endothelium-dependent acetylcholine (970%), but only modestly with endothelium-independent vasodilators, nitroglycerin (292%) and nitroprusside (340%). Despite eliciting the greatest overall forearm flow response, acetylcholine resulted in a smaller increase in conduit diameter (15.4%) than nitroglycerin (21.8%), and only a comparable change than nitroprusside (14.6%). Taken together, these results suggest that acetylcholine acts predominantly on resistance vessels, whereas nitrovasodilators affect mainly conduit vessels. In summary, transcutaneous ultrasonography can be used reliably to assess flow changes in the peripheral circulation. Combined with plethysmography, this technique is useful for determining the relative contribution of conduit and resistance vessels to peripheral flow, particularly in the assessment of endothelium-mediated vasodilation.

Modulation of vascular inflammation in vitro and in vivo by peroxisome proliferator-activated receptor-gamma activators

BACKGROUND

Peroxisome proliferator-activated receptor-gamma (PPARgamma) is expressed in atherosclerotic plaques and in endothelial cells. The possible effects of PPARgamma activators on endothelial activation and inflammatory response within the plaque are currently unknown.

METHODS AND RESULTS

We tested the hypothesis that PPARgamma activators inhibit vascular cell adhesion molecule (VCAM-1) and intercellular adhesion molecule (ICAM-1) expression in cultured endothelial cells (evaluated by flow cytometry) and homing of monocyte/macrophages to atherosclerotic plaques in vivo. In endothelial cells, the PPARgamma agonists troglitazone at 100 micromol/L and 15-deoxy-(Delta12,14)-prostaglandin J(2) (15d-PGJ2) at 20 micromol/L markedly attenuated the tumor necrosis factor-induced expression of VCAM-1 and ICAM-1. A significant inhibition of VCAM-1 expression was also evident at 5 and 10 micromol/L 15d-PGJ2 and 20 micromol/L troglitazone. Expression of E-selectin and PECAM-1 was not altered. To confirm the biological relevance of these results, we assessed the effects of troglitazone on monocyte/macrophage homing to atherosclerotic plaques in apoE-deficient mice. A 7-day treatment with troglitazone (400 mg/kg) significantly reduced monocyte/macrophage homing to atherosclerotic plaques (236+/-77 versus 177+/-43 macrophages, P=0.03); an even more striking inhibition was found at 3200 mg/kg troglitazone (344+/-76 versus 172+/-83 macrophages, P=0.005).

CONCLUSIONS

PPARgamma activators inhibit expression of VCAM-1 and ICAM-1 in activated endothelial cells and significantly reduce monocyte/macrophage homing to atherosclerotic plaques. These findings suggest that PPARgamma activators, currently used in treatment of type II diabetes, may have beneficial effects in modulating inflammatory response in atherosclerosis.

Reactive pulmonary artery vasoconstriction in pulmonary consolidation evaluated by color Doppler ultrasonography

A total of 122 patients with pulmonary consolidation on chest radiographs underwent color Doppler ultrasonography to evaluate hemodynamic change in regional pulmonary artery in pulmonary consolidation due to various causes. The diseases underlying pulmonary consolidation included 66 simple pneumonia, 37 obstructive pneumonia, 13 tumor consolidation and 6 pulmonary infarctions. Blood flow signals in consolidation were detected by color-flow mapping. The degree of reactive vasoconstriction was evaluated from analysis of the spectral waveform of the blood flow in the segmental pulmonary artery by several vessel resistance-indicating Doppler ultrasound (US) indices, including pulsativity index (PI), resistive index (RI), and acceleration time (AT). The results showed that reactive vasoconstriction was most marked in obstructive pneumonia, followed by simple pneumonia, and least in tumor consolidation (p < 0.001, Kruskal-Wallis test and p < 0.001, Dunn's test for comparison of PI, RI and AT values between different groups of pulmonary consolidation). No flow was detected in pulmonary infarction. We conclude that color Doppler US is a useful tool for evaluating reactive vasoconstriction in pulmonary consolidation. The different degrees of reactive vasoconstriction may be helpful in exploring the possible etiology of pulmonary consolidation.

Lung transplantation for patients with end-stage Sauropus androgynus-induced bronchiolitis obliterans (SABO) syndrome

Sauropus androgymus (SA), a vegetable of the Euphorbiaceae family, is a common food source in Malaysia. In Taiwan, over 30 patients have developed progressive respiratory failure after consuming the extract from raw SA leaves as a means of losing weight. Symptoms consistent with a severe obstructive ventilatory defect progressed, despite cessation of SA intake and treatment with bronchodilators, corticosteroids, cytotoxic agents and plasmaphresis. Five patients with end-stage Sauropus androgynus-induced bronchiolitis obliterans (SABO) syndrome underwent lung transplantation. There was no early mortality. One patient died of post-transplant lymphoproliferative disorder and another patient died of bronchial stenosis with infection, 5 and 3.5 months, respectively, post-transplantation. The remaining 3 patients have been followed from 29 to 34 months, with improved general condition and pulmonary function. Perfusion/ventilation scans revealed that these improvements were exclusively attributed to the functional grafts. We believe that lung transplantation is the only effective modality of treatment for patients with end-stage SABO syndrome.

Cough threshold in people with spinal cord injuries

BACKGROUND AND PURPOSE

The purpose of this study was to compare the cough threshold between people with and without spinal cord injury (SCI). The effect of smoking on cough threshold was also investigated.

SUBJECTS

The participants were 26 people with SCI (15 smokers, 11 nonsmokers) and 18 people without SCI (9 smokers, 9 nonsmokers).

METHODS

Aerosols of citric acid were delivered with incremental doubling concentration from 62.5 mmol to 2 mol. Cough threshold was defined as the first concentration of citric acid that induced at least 2 coughs, which is associated with large chest excursion and concurrently acoustic response.

RESULTS

The mean cough thresholds of smokers and nonsmokers with SCI (209 and 417 mmol, respectively) were lower than those of smokers and nonsmokers without SCI (467 and 1,072 mmol, respectively). The mean citric acid cough thresholds decreased in smokers with and without SCI when compared with nonsmokers with and without SCI.

CONCLUSION AND DISCUSSION

The cough sensitivity increased in subjects with SCI, and smoking could also increase the cough sensitivity. Training about the frequency and technique of cough in patients with SCI should be carefully monitored.

Removal of cardiac beat artifact in oesophageal pressure measurement by frequency analysis

Oesophageal pressure (Pes) measurements are important in medical research and useful in clinical diagnosis. Measurements, however, are contaminated heavily by cardiac artifacts. The spectrum and waveform of the Pes signal is obtained from the oesophageal balloon. Adaptive finite impulse response (AFIR) filter and modified adaptive noise cancellation (MANC) methods are adopted to filter out cardiac beat interference. These results are compared. In the frequency domain, frequency variations and spectral overlap between the Pes components and cardiac beat signal components impact on the performance of the filter. From our experimental results on power strength, the fourth or higher harmonics did not have any significant effect on the filter performance. However, the second harmonics of these signals had a significant effect on the filtering result. Thus, in the design of AFIR filters, attention is needed to minimise these effects. In frequency analysis, these harmonics or overlapping frequencies do not affect MANC. MANC was the better method for eliminating cardiac beat artifact in Pes measurement. The dynamic compliance (Cdyn) was also used to evaluate the performance of MANC and AFIR. The standard deviation of Cdyn was less than 0.15 using MANC, compared with standard deviations as high as 0.57 for AFIR. We conclude that MANC performs better than AFIR.

Abdominal weight and inspiratory resistance: their immediate effects on inspiratory muscle functions during maximal voluntary breathing in chronic tetraplegic patients

OBJECTIVE

To study the immediate effects of maximal voluntary (MV) breathing, with and without abdominal weight (AW) or inspiratory resistance (IR), on inspiratory muscle functions in chronic tetraplegic patients.

DESIGN

A crossover trial design.

SETTING

Rehabilitation department of a university hospital.

PARTICIPANTS

Nine tetraplegic men injured at the C4 to T1 levels, with a mean duration of injury of 72.8 months.

INTERVENTIONS

Each subject performed MV breathing without and with AW load (AWMV breathing) and IR load (IRMV breathing) separately.

MAIN OUTCOME MEASURES

Electromyographic (EMG) activity of the inspiratory muscles, mouth pressure, inspiratory flow, and inspiratory volume.

RESULTS

AWMV breathing evoked greater diaphragmatic EMG activity, inspiratory flow, and inspiratory volume than did IRMV breathing, although the increase of diaphragmatic EMG activity was not statistically significant. Conversely, IRMV breathing produced greater sternocleidomastoid EMG activity and negative mouth pressure than did AWMV breathing. Both AWMV and IRMV breathing evoked greater inspiratory muscle EMG activity than did MV breathing.

CONCLUSION

AW and IR loads have differential immediate effects on the inspiratory muscle functions during MV breathing in patients with chronic tetraplegia, suggesting that these two breathing maneuvers may have dissimilar mechanisms of training in such patients. The muscle EMG activity evoked during MV breathing with AW or IR is greater than that without a mechanical load, implying that mechanically loaded training in tetraplegic patients results in load compensatory adjustments via their respiratory motor output to improve respiratory function.

Antioxidants attenuate chronic hypoxic pulmonary hypertension

Because chronic hypoxia increases the production of oxygen radicals, we hypothesized that antioxidants attenuate chronic hypoxic pulmonary hypertension. In part 1, we examined the temporal progress in chronic hypoxic pulmonary hypertension in 46 Wistar rats exposed to hypoxia from 0-3 weeks. In part 2, we tested whether antioxidants attenuated chronic hypoxic pulmonary hypertension in 82 rats divided into 10 groups: control, fullerenol-1, U-83836E, dimethylthiourea-1, dimethylthiourea-2, hypoxia, hypoxia + fullerenol-1, hypoxia + U83836E, hypoxia + dimethylthiourea-1, and hypoxia + dimethylthiourea-2. Control animals breathed room air and were injected intraperitoneally with saline for 2 weeks. Fullerenol-1, U-83836E, and dimethylthiourea are antioxidants and were administered intraperitoneally for 2 weeks, except that dimethylthiourea was given either on days 3, 5, and 7 (dimethylthiourea-1), or on days 8, 10, and 12 (dimethylthiourea-2). Hypoxic animals were placed into a hypobaric chamber with a barometric pressure of 380 Torr for 2 weeks. Hypoxia + antioxidant groups were administered antioxidants during hypoxic exposure. We observed a gradual increase in pulmonary artery pressure, the weight ratio of right ventricle to left ventricle plus septum, and hematocrit during the 3 weeks of chronic hypoxia. These hypoxia-induced alterations were significantly attenuated by U-83836E and dimethylthiourea, but not by fullerenol-1. Neither the temporal alterations nor the antioxidant effects can be explained by the change in either tracheal neutral endopeptidase activity or the lung or plasma substance P level, perhaps because of the time lag in sampling. These results indicate that oxygen radicals play an important role in the development of chronic hypoxic pulmonary hypertension.

Lipoblastomatosis of the shoulder: unusual MR appearance

Lipoblastomatosis is a rare benign lipomatous tumour of childhood and infancy, classically showing high signal identical to fat on T1 weighted images. A case of histologically proven lipoblastomatosis in an infant is presented, in which MRI showed low signal on T1 weighted images identical to that of muscle instead of high signal. This appearance has not been previously reported.

Ventilatory and mouth occlusion pressure responses to hypercapnia in chronic tetraplegia

OBJECTIVE

To compare the ventilatory response to hypercapnia and the mouth occlusion pressure measured at 0.1 second following inspiration (P0.1) in hypercapnia between chronic tetraplegic and normal subjects.

DESIGN

A case-control study with an uneven sample size for the study of clinical disorders.

SETTING

Patients were recruited from the outpatient clinic of a rehabilitation department.

PARTICIPANTS

Seven normal men and 9 men with tetraplegia who had cervical cord injuries (C5-C8), with a mean injury duration of 9.7 yrs.

INTERVENTIONS

Pulmonary function tests were performed during resting, whereas minute ventilation (VE) and P0.1 were measured during CO2 rebreathing.

RESULTS

The maximal voluntary ventilation (MVV), vital capacity (VC), and maximal respiratory muscle strength in the tetraplegic subjects were significantly less than in the normal subjects. Both the ventilatory and P0.1 responses to hypercapnia were significantly reduced in tetraplegic as compared with normal subjects, but the reductions were eliminated by normalizing with maximal ventilatory performance (MVV or VC) and maximal inspiratory muscle strength (PImax), respectively.

CONCLUSIONS

Chronic tetraplegic persons have diminished ventilatory and P0.1 responses to hypercapnia. Respiratory muscle weakness may be a primary factor contributing to the diminished ventilatory response observed in these patients.

Primary pulmonary plasmacytoma with lobar consolidation: an unusual presentation

Extramedullary plasmacytoma is a rare form of plasma cell tumor that frequently involves the upper respiratory tract. Primary pulmonary plasmacytoma is even more rare. The usual presentation of primary pulmonary plasmacytoma is a solitary pulmonary nodule. We describe the case of a 58-year-old woman who presented with the chief complaints of progressive dyspnea on exertion, cough, and subsequently, hemoptysis. The main finding on chest imaging studies, including plain radiography, sonography, computed tomography, and magnetic resonance imaging, was consolidation of the right middle lobe. Percutaneous transthoracic lung biopsy of the right middle lobe demonstrated sheets of atypical plasma cells. Immunohistochemical study showed IgA lambda monoclonality. A bone marrow study and whole body bone scan showed normal findings. To the best of our knowledge, this is the first reported case of primary pulmonary plasmacytoma presenting with lobar consolidation of the lung but without a well-defined tumor mass.

Effects of an abdominal binder and electrical stimulation on cough in patients with spinal cord injury

We explored the effect of an abdominal binder, with or without electrical stimulation, on peak expiratory flow rate (PEFR) in 12 paraplegics with complete thoracic cord (T2-T12) injury (mean age 36.0 +/- 1.5 yr) and 12 quadriplegics with complete cervical cord (C4-C8) injury (mean age 36.2 +/- 1.9 yr). The cough was assessed by measuring the PEFR during forceful expiration in a sitting position. The subjects underwent the following experimental maneuvers in a random order with a 10-minute interval between any two maneuvers: 1) voluntary coughing, 2) voluntary coughing with an abdominal binder, and 3) voluntary coughing with an abdominal binder and electrical stimulation. The electrical stimulator (50 Hz with 300 microseconds pulse width) was applied to the abdominal wall. Data were analyzed using multivariate analysis of variance for repeated measures. The abdominal binder did not significantly increase PEFR in either paraplegics or quadriplegics; the abdominal binder combined with electrical stimulation significantly increased PEFR by 15% in the paraplegics and 18% in the quadriplegics. These results indicate that electrical stimulation combined with an abdominal binder improves the cough ability in patients with cervical or thoracic spinal cord injury.

Sonographic imaging of the trachea

We evaluated the feasibility of ultrasonography for imaging of the trachea and its effectiveness in the diagnosis and follow-up of patients with tracheal stenosis due to various diseases. Twenty normal volunteers and six adult patients with tracheal stenosis were included in the study group. Subjects were examined with ultrasonography in a supine position with the neck hyperextended or in a sitting position. At the level of the thyroid isthmus, the anterior tracheal wall thicknesses imaged by ultrasonography were 1.54 +/- 0.22 mm (mean +/- SD) and 1.22 +/- 0.18 mm for normal male and female volunteers, respectively. Ultrasonography could reveal the intrinsic tracheal wall lesions and extrinsic lesions compressing the trachea in patients with tracheal stenosis. These ultrasonographic images correlated with CT images. In conclusion, ultrasonography may be useful in imaging of the trachea.

Elevated serum levels of mucin-associated antigen in patients with acute respiratory distress syndrome

Increased serum levels of mucin-associated antigen have been previously demonstrated in patients with cystic fibrosis (CF) and interstitial pneumonia, and in lung-transplant recipients. The present study assessed the serum airway mucin levels in patients with acute respiratory distress syndrome (ARDS). An enzyme-linked immunosorbent assay (ELISA) method with a human-airway-mucin-specific monoclonal antibody (17Q2) was used to measure serum mucin levels in normal subjects, chronic smokers, patients with chronic bronchitis and other pulmonary diseases, patients with acute cardiogenic lung edema, and patients with ARDS. The serum mucin levels measured 9.9 +/- 0.8 ng/ml (mean +/- SEM, n = 59) in normal subjects, 12.7 +/- 1.6 ng/ml (n = 29) in chronic smokers, 21.8 +/- 1.9 ng/ml (n = 28) in patients with chronic bronchitis and other pulmonary diseases, 9.0 +/- 3.1 ng/ml (n = 5) in patients with acute cardiogenic lung edema. The serum mucin level was 53.8 +/- 6.6 ng/ml (n = 13) in patients with ARDS (p < 0.05, as compared with the four other groups). Serial measurements of serum mucin levels were obtained in patients with ARDS. Statistical analysis showed an inverse correlation of serial measurements of serum mucin with static respiratory-system compliance (p = 0.021), an inverse correlation of sequential serum mucin levels and log(Pa(O2)/Fl(O2)) (p = 0.016), and a positive correlation of sequential serum mucin levels and lung injury score (LIS) (p = 0.019). Gel-filtration analysis showed that mucin-associated antigens in ARDS sera were polydispersed and smaller than the antigens in normal sera. This study indicates that an increasing amount of degraded mucin occurs in patients with ARDS.

Comparison of inflammatory cytokine concentration and physiologic parameters in septic shock

Cytokine-related systemic intravascular inflammation may represent a common pathogenic link between initial insult and multiple organ failure in septic shock patients. We conducted a prospective study with controls in the National Taiwan University Hospital intensive care unit to compare plasma levels of tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and circulating intercellular adhesion molecule 1 (cICAM-1) with clinical physiologic parameters in the outcome of patients with septic shock. Healthy volunteers (n = 37) and patients with septic shock admitted to the unit from January to December 1994 (n = 31) were enrolled. Clinical data, APACHE (Acute Physiology and Chronic Health Evaluation) III scores, multiple organ failure scores, the presence of acute respiratory distress syndrome, and outcome were evaluated. The plasma levels of TNF-alpha, IL-6, and cICAM-1 were measured using enzyme-linked immunosorbent assay. Subgroups of survivors and nonsurvivors were compared for plasma levels of these factors or days 1, 2, 3, 7, and 14 after diagnosis of septic shock. Of the patients with septic shock, 20 survived and 11 died. The initial plasma levels of IL-6 were significantly higher in nonsurvivors (p < 0.05). There was a significant inverse correlation between plasma IL-6 level and survival in the first week (r = 0.4297-0.7242, p < 0.05). APACHE III score (r = 0.4335, p = 0.015), acute respiratory distress syndrome (r = 0.5913, p < 0.001), and multiple organ failure score (r = 0.736, p < 0.001) were more strongly (negatively) correlated with survival than the concentrations of TNF-alpha and cICAM-1 by Spearman's rank sum test. Our results showed that in patients with septic shock, of the inflammatory cytokines, only IL-6 showed significantly higher plasma levels in the nonsurvivor group. Inflammatory cytokine levels were not more strongly correlated with the outcome of patients with septic shock than physiologic parameters.

Assessment of mutations in Ki-ras and p53 in colon cancers from azoxymethane- and dimethylhydrazine-treated rats

Mutations in the Ki-ras oncogene and the p53 tumor suppressor gene are known to occur at high frequencies in human colon cancers. We measured the frequency of mutations in these two genes in colon adenocarcinomas obtained from a widely used experimental model of human colon carcinogenesis: F344 rats treated with the carcinogens azoxymethane (AOM) or dimethylhydrazine (DMH). We detected codon 12 mutations in Ki-ras in approximately 60% of colon adenocarcinomas induced by either carcinogen. We characterized the rat p53 intron-exon junctions to construct primers for polymerase chain reaction amplification of this gene. We discovered that the rat p53 gene was structurally different from the human p53 gene, as the rat gene was missing one intron between exons 6 and 7. Both single-stranded DNA conformational polymorphism analysis and direct DNA sequencing of the highly conserved regions of rat exons 5-7 were conducted because the corresponding human regions (exons 5-8) have been reported as being mutated most frequently in human colon cancers. Using these methods, we were unable to identify any p53 mutations in the highly conserved regions of exons 5-7 in either AOM- or DMH-induced colon adenocarcinomas. These data confirm that Ki-ras was mutated in most colon cancers in AOM- or DMH-treated rats but indicate that molecular alterations in the p53 gene, if they occur in this animal model, are different from most p53 mutations in human colon cancers.

Efficacy of tracheal gas insufflation in acute respiratory distress syndrome with permissive hypercapnia

This study was conducted to assess the CO2-elimination efficiency of tracheal gas insufflation (TGI) in 20 patients with acute respiratory distress syndrome and to compare its efficacy during volume-controlled (VCV) and pressure-controlled ventilation (PCV). TGI was initially applied as an adjunct to VCV, with continuous flows (Vcath) of 4 and 6 L/min delivered through a catheter positioned 2 cm above the carina. Total effective tidal volume (VTeff) was held constant. The percent reductions in PaCO2 (% delta PaCO2) were 13.3 +/- 2.1 and 16.7 +/- 2.7% at Vcath 4 and 6 L/min, respectively, which correlated well with the percent reduction in the end-tidal PCO2 from baseline (% delta PETCO2) (r = 0.75, p < 0.001). An inverse relationship (r = -0.65, p < 0.001 and r = -0.59, p < 0.01 at Vcath 4 and 6 L/min, respectively) was found between the % delta PaCO2 and the baseline ratio of artery to PETCO2 difference to PaCO2, which was determined as the fraction of alveolar dead space (VDalv) relative to total alveolar ventilation. Twelve patients were subsequently switched to PCV combined with Vcath 6 L/min, which provided a % delta PaCO2 of 16.1 +/- 3.0% (p = NS versus 17.1 +/- 2.6% during VCV). These data suggest that in patients with ARDS the change in PETCO2 may be helpful in predicting the decrement in PaCO2 during TGI, and the existence of a high VDalv tends to limit its effectiveness. Further, the efficacy of TGI with VCV is equivalent to that with PCV.

Immunoprophylaxis of allergen-induced immunoglobulin E synthesis and airway hyperresponsiveness in vivo by genetic immunization

The efficacy of an "allergen-gene immunization" protocol in altering allergic response was examined. Intramuscular injection of rats with a plasmid DNA encoding a house dust mite allergen into the muscle results in its long-term expression and the induction of specific immune responses. Significantly, this approach prevents the induction of immunoglobulin E synthesis, histamine release in bronchoalveolar fluids, and airway hyperresponsiveness in rats challenged with aerosolized allergen. Furthermore, this suppression is persistent and can be transferred into naive rats by CD8+ T cells from gene-immunized rats. These findings suggest that allergen-gene immunization is effective in modulating allergic responses, and may provide a novel therapeutic approach for allergic diseases.

Image comparison of real-time gray-scale ultrasound and color Doppler ultrasound for use in diagnosis of minimal pleural effusion

To assess the value of color Doppler ultrasound in distinguishing minimal pleural effusion from pleural thickening, a prospective analysis was done on the ultrasonographic findings in 51 patients. Real-time, gray-scale, and color Doppler chest ultrasound examinations were carried out by different sonographers who had no clinical information concerning the patients. The sonographer evaluated the images for internal echogenicity of the effusion, pleural lesions that change shape with respiration, and movable septa and echo-densities in pleural space in conventional gray-scale as well as color signal in color Doppler ultrasound. Of the 35 patients with true effusion, 33 had positive color signal (sensitivity 94.3%, 95% confidence intervals [CI] 89 to 98.6%); in 16 patients without effusion, none had color signal (specificity 100%, 95% CI 83 to 100%). Although real-time, gray-scale ultrasound is also sensitive for detecting minimal effusion (sensitivity 100%, 95% CI 92 to 100%), it is less specific (specificity 68.7%, 95% CI 46 to 91.5%). Five of 16 examinations showing fluid-like lesions were found to be deceptive. With relatively high sensitivity and specificity, this method proved to be a useful diagnostic aid to real-time, gray-scale ultrasound for diagnosis of minimal or loculated effusion.

Superior vena cava syndrome. Rapid histologic diagnosis by ultrasound-guided transthoracic needle aspiration biopsy

We prospectively analyzed the diagnostic yield and safety of ultrasound (US)-guided transthoracic needle aspiration biopsy in the histologic diagnosis of 40 patients with superior vena cava (SVC) syndrome. During a 4-yr period, 40 patients with SVC obstruction were admitted to National Taiwan University Hospital. Of these patients 10 had histologic confirmation by sputum cytology (3 patients), fiberoptic bronchoscopy with biopsy (2 patients), or lymph node biopsy (5 patients) at admission. A total of 30 undiagnosed patients underwent real-time ultrasonographic (US) evaluation as well as color Doppler imaging. Patients with tumor detectable by US underwent US-guided transthoracic needle aspiration biopsy. Of the 30 patients who received US chest examination, 29 had widening of the upper mediastinal shadows in the chest radiographs. In 27 patients tumors were detected by chest US. After assessment of collateral vessels by color Doppler US, these 27 patients underwent US-guided transthoracic needle aspiration biopsies; histologic diagnoses were confirmed in 25. The diagnostic yield was 83.3%. The mean duration from admission to histologic diagnosis was 2.1 days. None of the patients developed complications. We conclude that chest US and color Doppler images are useful tools for evaluation of patients with SVC syndrome. US-guided transthoracic needle aspiration biopsy appears to be a safe, effective, and rapid approach for obtaining an accurate histologic diagnosis. Specific treatment can thus be initiated without delay.

Ultrasound guided aspiration biopsy for pulmonary tuberculosis with unusual radiographic appearances

BACKGROUND

Pulmonary tuberculosis can produce unusual radiographic appearances and negative results of sputum and bronchoscopic examinations are common. This study assessed the value of ultrasound guided aspiration biopsy in the diagnosis of pulmonary tuberculosis with unusual radiographic appearances.

METHODS

Thirteen patients, ultimately diagnosed as having tuberculosis, underwent a chest ultrasonographic examination between June 1984 and August 1991. All had sputum available for examination and nine were also examined by bronchoscopy. Ten patients who had a negative sputum smear and negative bronchoscopic brushing smears underwent ultrasound guided aspiration or biopsy. Percutaneous aspiration was performed with a 22 gauge needle. If the smear did not reveal acid fast bacilli, a biopsy sample was taken with a 16 gauge Tru-cut needle to obtain a histological diagnosis.

RESULTS

The ultrasonographic examination delineated the more complex nature of the lesions better than the chest radiograph. Ultrasound guided aspiration biopsy provided the diagnosis in nine of 10 patients, while the sputum smear and culture provided diagnosis in five of 13, and bronchoscopy in four of nine. In terms of rapid diagnosis, ultrasound guided aspiration biopsy gave the diagnosis in eight of 10 cases. No patient developed a major complication.

CONCLUSION

Ultrasonography can direct the needle to the most suitable part of a lesion to obtain the relevant specimens. The diagnostic yield is high and the procedure is relatively safe. It is especially helpful in patients with negative results of sputum and bronchoscopic examinations.

Ultrasound study in unilateral hemithorax opacification. Image comparison with computed tomography

The diagnostic capability of chest ultrasonography was assessed for use in evaluation of patients presenting with opacification of unilateral hemithorax on chest radiography. Hemithorax opacification provided an "ultrasonic window" for ultrasonic wave penetration to detect any underlying diseases. Fifty patients were included over a study period of 24 months. All had received both chest ultrasonography (US) and computed tomography (CT) examinations, and their underlying diseases had been confirmed by various methods. Comparisons between the findings of chest US and of CT were made in three compartments: pleura, parenchyma, and mediastinum. Diagnostic sensitivity and specificity of chest US was defined by using CT as the "gold standard." The ability of US to detect underlying diseases was comparable to that of CT in pleural and parenchymal lesions. But US was inferior to CT for demonstration of mediastinal lesions. The diagnostic sensitivity of US was 95.1% in pleural lesions, 82.8% in parenchymal lesions, and only 30% in mediastinal lesions. US missed 14 lesions demonstrated by CT (seven mediastinal lesions, five parenchymal tumors, and two pleural nodules), but it showed six lesions that CT had failed to detect (four focal pleural thickening and two parenchymal tumors). US-related procedures were performed (thoracentesis in 33 patients, pleural biopsy in 10 patients, and US-guided aspiration/cutting biopsy in 11 patients) with a high diagnostic yield and no complications. The conclusion was that chest ultrasonography is useful, particularly as a first-step examination for patients with total or nearly total opacification of the hemithorax.

Ultrasonographic evaluation of pulmonary consolidation

A total of 161 patients with lobar or segmental consolidation were examined by realtime ultrasound and Doppler ultrasound. Air bronchograms were detected in 141 patients, fluid bronchograms in 27 patients, and parapneumonic effusion in 74 patients. In 36 patients with necrotizing pneumonia, ultrasound detected microabscesses in 33 (91.7%) compared with the air-fluid levels detected by standard chest radiographs in 20 patients (55.6%; p less than 0.05). Of 31 patients with tumors causing obstructive pneumonitis, 29 (93.5%) had tumors detected by chest ultrasound, whereas only 11 patients (35.5%) had chest radiographs that suggested a tumor was causing the obstructive pneumonitis (p less than 0.05). Chest ultrasound was used to guide thoracentesis for parapneumonic effusion in 65 patients, with a 100% success rate. Twenty-six patients with necrotizing pneumonia underwent ultrasound-guided needle aspiration of microabscesses. The procedure was successful in 24 patients (92.3%), and 21 patients (80.8%) had microbiologic confirmation. Twenty patients with tumor-associated obstructive pneumonitis received needle aspiration biopsy under ultrasound guidance; 19 patients (95.0%) had the histology confirmed. Five patients with malignancy manifesting as pulmonary consolidation underwent a diagnostic ultrasound-guided needle aspiration biopsy. Five patients (3.8%) developed complications of minimal pneumothorax or mild hemoptysis in 132 episodes of needle aspiration. We conclude that ultrasonography is useful for the evaluation of pulmonary consolidation. It can also be used for needle aspiration guidance for etiologic diagnosis of patients with complicated pneumonia.

Ultrasound-guided core biopsy of thoracic tumors

Two hundred and eighteen patients, with thoracic tumors larger than 3 cm in size, underwent ultrasound-guided percutaneous transthoracic core biopsy with a large-bore Tru-Cut needle. Fifty-five tumors were in the mediastinum, and 122 tumors were located at subpleural area, and 42 tumors were within the lungs. In 122 subpleural tumors, the sensitivity of ultrasound-guided core biopsy for the diagnosis of malignancy was 96.8%, and accuracy was 97.5%. Sensitivity for the diagnosis of malignant tumors located within the lungs was 94.6%, and accuracy was 95.2%. In 54 patients with mediastinal tumors, definite histologic diagnosis could be obtained in 48 patients (88.9%). The sensitivity of ultrasound-guided biopsy for the diagnosis of malignancy in these 48 mediastinal tumors was 97.1%, with an accuracy of 97.9%. Three patients had complications with minimal pneumothorax and one with mild hemoptysis. We conclude that percutaneous transthoracic core biopsy with Tru-Cut needle under ultrasound guidance is a safe and sensitive way to obtain specimens for accurate histologic diagnosis of thoracic tumors. The diagnostic yield is high, and the technique, relatively simple, can also be used for outpatients.

Effects of smoked marijuana of varying potency on ventilatory drive and metabolic rate

Ventilatory responses to hypercapnia in experienced marijuana smokers have previously been shown to decrease, increase, or not change acutely after marijuana. In one study, minute ventilation (VE) and O2 consumption (VO2) increased but hypoxic ventilatory response did not change after smoking marijuana. We further investigated the effects of marijuana of increasing potency (0, 13, and 20 mg THC) on ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia in 11 young, healthy men who smoked marijuana regularly but refrained from any smoked substance, alcohol, caffeine, or other drugs for greater than or equal to 12 h before study. Ventilatory and P0.1 responses to hypoxia and hypercapnia were measured on 3 separate days before and 5 and 35 min (hypoxia) and 15 and 45 min (hypercapnia) after smoking. In a companion 3-day study, 12 young male habitual marijuana smokers underwent measurements of VE, VO2, and CO2 production (VCO2) before and 5 to 135 min after smoking marijuana containing 0, 15, or 27 mg THC. None of the active marijuana preparations caused significant changes in ventilatory or P0.1 responses to either hypercapnia or hypoxia or in resting VE, VO2 or VCO2. We conclude that smoking marijuana (13 to 27 mg THC) has no acute effect on central or peripheral ventilatory drive or metabolic rate in habitual marijuana smokers. These conclusions cannot be applied to infrequent users of marijuana without further study.

Value of sonography in determining the nature of pleural effusion: analysis of 320 cases

To assess the value of sonography in determining the nature of pleural effusions, we prospectively analyzed the sonographic findings in 320 patients with pleural effusion of various causes (224 with exudates and 96 with transudates). The nature of the effusions was established on the basis of chemical, bacteriologic, and cytologic examination of pleural fluid; pleural biopsy; and clinical follow-up. All patients had high-frequency, real-time sonography performed by one of three sonographers who had no clinical information concerning the patients. The sonographer evaluated the images for internal echogenicity of the effusion, thickness of the pleura, and associated parenchymal lesions of the lung. The images were also printed out and interpreted a second time by the other two sonographers to reach a consensus. Our results showed that the two types of effusions could be distinguished on the basis of sonographic findings. Transudates were anechoic, whereas an anechoic effusion could be either a transudate or an exudate. Pleural effusions with complex septated, complex nonseptated, or homogeneously echogenic patterns were always exudates (p less than .01). Sonographic findings of thickened pleura and associated parenchymal lesions in the lung also were indicative of an exudate (p less than .01). Homogenous echogenic effusions were due to hemorrhagic effusion or empyema. Sonographic evidence of a pleural nodule was a specific finding in patients with a malignant effusion. We conclude that sonography is useful in determining the nature of pleural effusion.

Ultrasonographically guided biopsy of thoracic tumors. A comparison of large-bore cutting biopsy with fine-needle aspiration

A prospective study to compare the safety and diagnostic accuracy of ultrasonographically guided transthoracic large-bore cutting biopsy histologic examination with fine-needle aspiration cytologic examination was conducted in 149 patients with thoracic tumors (29 mediastinal tumors and 120 pulmonary masses). The authors found that large-bore cutting biopsy under ultrasonographic guidance could be as safe as fine-needle aspiration, whereas diagnostic accuracy was significantly higher (97% versus 59% in malignant tumors, respectively, P less than 0.05; 85% versus 33% in benign lesions, respectively, P less than 0.05). The size, depth, and location of lesions did not influence the results of transthoracic needle aspiration or cutting biopsy. In 77 patients with primary lung cancer, fine-needle aspiration cytologic examination, although achieving 88% positive cytologic results, identified the histologic cell type accurately in only 70%, whereas Tru-Cut (Top Surgical, Tokyo, Japan) biopsy was 97% accurate in confirmative histologic diagnosis. Fourteen patients had discordant cytologic and histologic diagnoses, and the cases of 3 (3.9%) were between small cell lung cancer and non-small cell lung cancer. The diagnostic accuracy of Tru-Cut biopsy also was significantly higher than that of fine-needle aspiration in metastatic cancers (90% versus 33%, respectively) and mediastinal tumors (100% versus 46%, respectively). The authors conclude that transthoracic cutting biopsy under ultrasonographic guidance is safe and has a higher diagnostic accuracy as compared with fine-needle aspiration. This technique is particularly useful for benign lesions or tumors with pleomorphic morphologic characteristics, such as lymphomas and thymomas.

Experimental evaluation of ten clinically used arterial prostheses

The arterial grafts currently in use are classified into five basic categories; 10 different commercially available prostheses were chosen to represent these categories. The Vascutek and Bionit are made from knitted Dacron and have medium porosity, requiring preclotting by the surgeon. The DeBakey Soft Woven and Plasma TFE grafts are made from woven Dacron and have low porosity, not requiring preclotting under most circumstances. Also studied were woven and knitted grafts with leakage resistance referred to as "impervious" Dacron grafts: the Vascutek Gelseal, the Bard Albumin Coated DeBakey Vasculour II, the Microvel with Hemashield, and the albumin saturated, autoclaved DeBakey Soft Woven graft. Gore-Tex and Impra are expanded polytetrafluoroethylene grafts which do not require preclotting. For each type, five grafts 6 cm long and 8 mm in diameter were implanted in the descending thoracic aorta of healthy adult dogs for 16 weeks. The physical characteristics, biocompatibility, and healing patterns varied according to the structure and treatment of the grafts. Pretreatment with biomaterials during manufacture is quite effective in preventing transinterstices blood loss during implantation, but results in altered physical qualities, increased thrombogenicity and delayed healing in comparison to the effects of preclotting with autogenous blood at the time of implantation.

Comparative evaluation of the elasticity and flexibility of bioimpregnated knitted grafts

Longitudinal elasticities of whole human blood clot, whole canine blood clot, Factor XIII cross-linked fibrin, glutaraldehyde-fixed human albumin, and formaldehyde-fixed collagen, gelatin and collagen/gelatin were determined and normalized to human whole blood clot. Matrices of a knitted Dacron graft were then impregnated with albumin, collagen, and collagen/gelatin and their longitudinal elasticities were determined and normalized to a preclotted graft. Comparisons were also made for the longitudinal elasticities of a virgin graft, a manipulated control for a preclotted graft, and a manipulated control for the matrix-impregnated grafts. Flexibilities were then calculated based on the weights and elasticities of these grafts and normalized to the flexibility of the preclotted graft. Fibrin had twice and 39 times more longitudinal elasticity than human blood clot and collagen, respectively. The preclotted graft has longitudinal elastic properties similar to a virgin graft, and is 2.8, 2, and 1.4 times more elastic than the albumin, collagen and collagen/gelatin grafts, respectively. The preclotted graft was 2.5, 2, and 1.4 times more flexible than the albumin, collagen and collagen/gelatin grafts, respectively.

Evaluation of ultrasonically guided biopsies of mediastinal masses

Eighty patients with roentgenographic evidence of mediastinal abnormalities were examined with ultrasonography. Fifty-four lesions were malignant, and 26 lesions were benign. The histologic diagnoses were confirmed by ultrasonically guided fine needle aspiration/cutting needle (Tru-Cut) biopsy, surgical specimens, or transbronchial biopsy. There were no unique ultrasonographic features for diagnosis of specific tumors. Ultrasonically guided aspiration biopsies (UGAB) were performed in 44 of the malignant lesions and in 14 of the benign lesions (nine of the noncystic lesions and five of the cystic lesions). Cytologic diagnosis of malignancies was obtained in 34 (77 percent) of these 44 malignancies; however, accurate histologic classifications of malignancies were achieved in only 24 (55 percent). Accurate diagnoses were achieved in only three (33 percent) of the nine noncystic benign lesions. Ultrasonically guided cutting biopsies (UGCB) were performed in 24 malignant and five benign lesions. All attempts yielded satisfactory specimens for histologic diagnosis. Using UGAB and UGCB together, a positive diagnosis was achieved in 89 percent (39/44) of the malignancies, and accurate histologic diagnosis was achieved in 89 percent and 78 percent (7/9) in malignant and benign noncystic lesions, respectively. Correct histologic diagnosis with UGAB alone is lower in thymoma (55 percent [6/11]) and lymphoma (30 percent [3/10]) but higher in lung cancer (67 percent [8/12]) and metastatic cancer (78 percent [7/9]). There were no complications in this series. We conclude that ultrasonography with UGAB has a high diagnostic yield in diagnosing mediastinal tumors, and UGCB is necessary for thymic tumors, lymphoma, and benign lesions.