Rapid Noninvasive Diagnosis Research Articles

Diagnosis of vocal cord dysfunction in asthma with high resolution dynamic volume computerized tomography of the larynx

Vocal cord dysfunction (VCD) often masquerades as asthma and reports have suggested that up to 30% of patients with asthma may have coexistent VCD. Diagnosis of VCD is difficult, in part because it involves laryngoscopy which has practical constraints, and there is need for rapid non-invasive diagnosis. High speed 320-slice volume CT demonstrates laryngeal function during inspiration and expiration and may be useful in suspected VCD. Endoscopy and high resolution 320-slice dynamic volume CT were used to examine and compare laryngeal anatomy and movement in a case of subglottic stenosis and in a patient with confirmed VCD. Nine asthmatics with ongoing symptoms and suspected VCD also underwent 320-slice dynamic volume CT. Tracheal and laryngeal anatomy and movement were evaluated and luminal areas were measured. Reductions in vocal cord luminal area >40%, lasting for >70% duration of inspiration/expiration, were judged to be consistent with VCD. Studies of subglottic tracheal stenosis validated anatomical similarities between endoscopy and CT images. Endoscopy and 320-slice volume CT also provided comparable dynamic images in a patient with confirmed VCD. A further nine patients with a history of severe asthma and suspected VCD were studied using CT. Four patients had evidence of VCD and the median reduction of luminal area during expiration was 78.2% (range 48.2-92.5%) compared with 10.4% (range 4.7-30%) in the five patients without VCD. Patients with VCD had no distinguishing clinical characteristics. Dynamic volume CT provided explicit images of the larynx, distinguished function of the vocal cords during the respiratory cycle and could identify putative VCD. The technique will potentially provide a simple, non-invasive investigation to identify laryngeal dysfunction, permitting improved management of asthma.

Improved survival of surgery for acute type A aortic dissection: impact of noninvasive diagnosis and hemostatic surgical management.

In the past decade, progress in cardiovascular technology has been incorporated into the surgical treatment of acute type A dissection resulting in remarkable improvement. Factors in this progress encompass rapid noninvasive diagnosis, intraoperative introduction of aprotinine, surgical glue, sealed grafts, and refined surgical technique. The objective of this study is to identify which factors contributed to the improvement of the surgical outcome of acute type A dissections. Between January 1989 and February 2001, 78 consecutive patients had emergency surgeries for acute type A dissection. The initial 31 patients (group I) received preoperative angiography, when possible. Since 1996, the next 47 patients (group II) have received noninvasive rapid diagnosis with hemostatic surgical management. This included aggressive proximal resection and judicious use of gelatin resorcine formol glue and felt strips. Between the two groups, in-hospital mortality and morbidity, incidence of neurological complications, late survival and cardiovascular events were compared. Risk factors for in-hospital death were investigated with univariate and multivariate analysis. The in-hospital mortality was significantly improved in group II (4.3%) compared with group I (29.0%). Overall mortality was 14.1%. Multivariate analysis revealed preoperative limb ischemia and delayed timing of operation (> 3 hours after arrival) as independent risk factors for in-hospital death. Late survival at 5 years was 61.5+/-7.5%. Between the two groups there was no significant difference in late survival or cardiovascular events. Immediate surgical intervention, using rapid noninvasive diagnosis with hemostatic management, substantially improves the surgical outcome of acute aortic dissection.

Management of aortic dissection

Patients with aortic dissection are divided into two main groups: those with hypertension and those with syndromes involving hereditary defects of the aortic wall. The common finding in the setting of both Marfan syndrome and hypertension is dilatation of the aorta. The biological events that may lead to dissection are a decrease in the holding power of the internal layer, an increase in blood pressure, or an increase in aortic diameter combined with a decrease in wall thickness. Treatment of established acute type A dissection is still associated with a hospital mortality of greater than 10% and long-term complications from persistent blood flow in the distal false lumen. The main therapeutic challenge is to prevent aortic dissection by screening of aortic root diameter in patients at risk, together with life-long beta-blockade for Marfan patients. In patients with suspected dissection, the preference is for rapid noninvasive diagnosis and early surgical repair to reduce the risk of malperfusion and irreversible organ damage. Results of surgery have improved, with an increasingly conservative approach to repair of the aortic valve with biological glues. Repair is now routinely carried into the aortic arch using improved methods of cerebral protection such as retrograde cerebral perfusion through the superior vena cava. Nevertheless, there remains scope for further innovation in the prevention and treatment of this difficult problem.

Rapid noninvasive diagnosis and surgical repair of acute ascending aortic dissection

Angiography has been considered the gold standard for the diagnosis of acute dissection of the ascending aorta, but it may increase mortality by imposing an unnecessary delay before surgical repair. In addition, coronary angiography has often been considered essential as well. From 1988 to 1993, 37 patients (median age 61 years, 30 men and 7 women) had acute dissection of the ascending aorta. All of the initial 15 patients (group I) had angiography, even through the diagnosis of aortic dissection had already been made noninvasively in 14; six (40%) of 15 died, three of aortic rupture and none of complications of coronary artery disease. Among the next 22 patients (group II), 21 had a noninvasive diagnosis of acute dissection of the ascending aorta (eight by echocardiography; 13 by computed tomography), and 19 (86%) were operated on without angiography; two died (9%, p = 0.03 versus group I) and neither death was due to aortic rupture or coronary artery disease. Overall, either root or selective coronary angiography was attempted in 18 of 37 patients, but it documented coronary artery disease in only two patients (11%). Coronary artery disease was found in four other patents at autopsy; three of them, including two that died of aortic rupture, had angiography that failed to reveal the coronary artery disease. Noninvasive diagnosis of acute dissection of the ascending aorta is reliable and avoids the risks and delays inherent in invasive angiography. Rapid noninvasive diagnosis of aortic dissection and avoidance of routine angiography appear to improve survival by expediting surgical intervention and thus decreasing the risk of aortic rupture.

Rapid Noninvasive Diagnosis of Pneumocystis carinii from Induced Liquefied Sputum

Pneumocystis carinii organisms cluster in alveolar casts. A method for concentrating alveolar casts in sputum specimens might improve the diagnostic usefulness of sputum studies in possible cases of pulmonary infection with Pneumocystis carinii. The use of sputum induction to detect Pneumocystis carinii was studied in 40 consecutive patients with known or suspected human immunodeficiency virus infection having bronchoscopy for evaluation of pulmonary disease. Sputum produced by deep coughing induced by 3% saline via a jet nebulizer was liquefied with dithiothreitol, and cells were sedimented and stained. Liquefaction of mucus allowed concentration of alveolar casts where P. carinii cysts were readily identified. A total of 28 patients were found to have P. carinii, which was detected in concentrated sputum in 21 of 38 patients, unconcentrated sputum in 10 of 38 patients, and by bronchoscopy in 25 of 37 patients. Sensitivity of concentrated sputum compared with bronchoscopy was 78% (95% CI, 58 to 90), with a negative predictive value of 71% (95% CI, 47 to 87). Values for unconcentrated sputum were 43% (95% CI, 25 to 63) and 48% (95% CI, 30 to 67), respectively. Liquefaction of adequately induced sputum facilitates processing and interpretation and increases yield for P. carinii, eliminating the need for invasive procedures in most patients.

EXAMINATION OF A MYOPATHY BY PHOSPHORUS NUCLEAR MAGNETIC RESONANCE

A 16-year-old boy with myopathy, ophthalmoplegia, and raised basal metabolic rate was examined by the non-invasive technique of phosphorus-31 nuclear magnetic resonance ( 31P NMR). The muscles of the forearm showed an abnormal 31P NMR spectrum with a high inorganic phosphate (Pi) content in relation to phosphocreatine (PCr) (PCr/P i=4; control=10). This finding was compatible with the abnormality of mitochondrial function already established by biopsy and offers in addition an explanation for the raised oxygen consumption in this patient. The method of 31P NMR is suited to rapid non-invasive diagnosis in various muscle disorders.

The Evaluation of Head Trauma by Computed Tomography

A retrospective study of 133 patients with documented head trauma is presented. Computed tomography (C.T.) has replaced cerebral angiography in the evaluation of these patients at our institutions. C.T. provides a rapid noninvasive diagnosis, plus accurate localization of lesions; it also allows for the assessment of multiple lesions. The authors feel that C.T. should be the first neurological mode of investigation after plain skull radiographs. It is important to obtain good quality scans, and intravenous sedation or general anaesthesia may be required.