Biomedical subjects

R F Bellamy

Publications and source records attributed to R F Bellamy.

At least 19 recordsLinked to original sources

PubMed1991

Primary cysts and tumors of the mediastinum.

A retrospective analysis was performed on 230 patients with primary cysts and tumors of the mediastinum seen at our institution from January 1944 to April 1989. We divided these patients into two groups. Group 1 was seen before 1970 and group 2 was seen from January 1970 to April 1989. There was a significant increase in the prevalence of malignancy in group 2 (47.2% versus 17.1%; p less than 0.0001) due to an increase in the number of lymphomas (22.6% versus 3.5%; p less than 0.001) and malignant neurogenic tumors (6.8% versus 1.1%; p = 0.0528). There was a significant increase in the number of malignant tumors in the anterior (59.5% versus 30.9%; p = 0.0022) and paravertebral (28.5% versus 2.8%; p = 0.0027) compartments in group 2. More patients with these tumors were symptomatic in group 2 (63.6% versus 5%; p = 0.0422). There was an increase of ancillary diagnostic studies performed to evaluate these tumors (76.0% versus 34.5%; p = 0.0422). Logistic regression analysis identified date of presentation (p less than 0.005), symptoms (p less than 0.01), size (p less than 0.005), and the anterior mediastinal compartment (p less than 0.005) as preoperative predictors of malignancy. The surgical approach to these tumors included more median sternotomy (30.1% versus 10.7%; p = 0.0008), anterior mediastinotomy, and cervical mediastinoscopy in group 2 (1.1% versus 17.5%; p = 0.0002). Long-term results support surgical resection in benign lesions and an aggressive multimodality approach to malignant lesions.

Adolescent↗

PubMed1990

Three-dimensional image reconstruction for planning of a complex cardiovascular procedure.

A rare left subclavian artery aneurysm associated with a congenital arch anomaly was difficult to visualize using standard radiographic techniques. Three-dimensional computer imaging produced a clear depiction of this unusual anatomy and simplified the preoperative planning.

Adult↗

PubMed1990

True emergency coronary artery bypass surgery.

Previous reports of emergency coronary artery bypass grafting often included cases that were not true surgical emergencies, thereby creating inappropriately favorable results. To accurately investigate this important subgroup of patients, we analyzed our recent experience with truly emergent coronary artery bypass grafting. From January 1984 to January 1989, 117 patients underwent true emergency bypass grafting for acute refractory coronary artery ischemia. Clinical deterioration was associated with failure of percutaneous angioplasty in 37 patients and instability during diagnostic catheterization in 13 patients. Refractory ischemia developed in the remaining patients while on the ward or in the intensive care unit. All operations were performed within four hours of surgical consultation, most within one hour. Overall in-hospital operative mortality was 14.5% (17/117), and 76.5% of deaths (13/17) were due to cardiac-related causes. Major morbidity occurred in 35.9% (42/117). Univariate analysis isolated ejection fraction, extent of coronary artery disease, previous myocardial infarction, hypertension, need for inotropic support, use of an intraaortic balloon pump, and cardiopulmonary resuscitation as risk factors for operative mortality. Stepwise multivariate analysis confirmed that previous myocardial infarction, hypertension, cardiopulmonary resuscitation, and reoperation were independently significant risk factors. Age, sex, diabetes, left main disease, and peripheral vascular disease had no significant impact on the prognosis. The 4% operative mortality (2/50) for patients taken directly to the operating room from the catheterization suite was significantly lower than the 22.4% mortality (15/67) associated with emergencies arising on the ward or intensive care unit (p less than 0.01). A logistic risk equation developed from this population accurately modeled operative mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Computerized tomography in the evaluation of myasthenia gravis.

Thymomas occur in 10% to 15% of patients with myasthenia gravis. Since not all patients are referred for thymectomy, a test that could reliably predict the presence or absence of a thymoma would be of great assistance in the management of these patients. We studied all patients referred for thymectomy at Walter Reed Army Medical Center from 1983 to 1989. Complete records were available for 13 patients. Computerized tomography (CT) correctly predicted the presence of a thymoma in one patient and falsely predicted a thymoma in a patient with a thymic cyst; it accurately predicted the absence of a thymoma in the remaining 11 patients. The sensitivity of CT scanning was 100%, the specificity was 92%, and the accuracy was 92%, results that are in agreement with previously published data. Compared to conventional chest roentgenography, CT scanning provided a more precise anatomic localization, and accurately predicted local invasion. We recommend a CT scan of the mediastinum in all patients with myasthenia gravis to avoid delayed diagnosis of thymoma in patients who normally would not be referred for thymectomy.

Adult↗

PubMed1990

Risk assessment in urgent/emergent coronary artery surgery.

A statistical model has been developed to allow for prediction of individual patient prognosis following urgent/emergent coronary artery bypass grafting (CABG). None of the models previously described for use in coronary artery surgery has been tested with a prospective patient series that confirms the true predictive capacity of the model. Ideally, the predictive ability of such models should be validated with prospective trials. To examine the feasibility of statistical modeling in this clinical context, a computerized model based on the theorem of Bayes was developed to predict operative mortality for urgent coronary artery surgery. The presence or absence of 20 risk factors was determined for each of 405 consecutive patients undergoing urgent coronary artery surgery from January 1984 to January 1989. The first 100 patients were used to develop a database for the model, which was then used to prospectively evaluate the remaining 305 patients. There was good agreement between predicted and observed results. Models of this kind are particularly advantageous because of the ability to (1) accommodate multiple risk factors, (2) become tailored to a specific practice, and (3) determine individual rather than group prognosis. Validation with a prospective trial confirms the practical utility of this approach. This model has reliably predicted the risk associated with urgent coronary artery surgery and may provide important clinical information for the management of patients being evaluated for urgent revascularization.

Algorithms↗

PubMed1989

Use of artificial intelligence for the preoperative diagnosis of pulmonary lesions.

The relatively new field of artificial intelligence has spawned a variety of techniques associated with computer-assisted diagnosis. These techniques have been applied to the diagnosis of pulmonary lesions, but previous reports have focused on medical rather than surgical populations and the results have been evaluated using only retrospective patient surveys. We used a Bayesian algorithm to develop a diagnostic computer model for prospectively evaluating patients undergoing thoracotomy for suspected pulmonary malignancy. Patients who had a preoperative diagnosis were not included. Preoperative clinical and radiographic parameters for 100 consecutive patients were prospectively entered into the diagnostic model, which then categorized the lesion as benign or malignant. The computer predictions agreed with the final histological diagnosis in 95 of the 100 patients. The sensitivity was 96% and the specificity was 89% for this prospective series. These results indicate that the computer-assisted diagnosis of pulmonary lesions may have a role in this clinical setting.

Adult↗

PubMed1989

Cervical spine immobilization of penetrating neck wounds in a hostile environment.

Current guidelines concerning trauma suggest that cervical spine immobilization be performed on all patients with penetrating wounds of the neck. This study was undertaken to examine the risks and benefits likely to be found when such care is provided in a hazardous environment, such as the battlefield, or the scene of a terrorist attack or domestic criminal action. Data for casualties from the Vietnam conflict were reviewed to determine the potential benefit of cervical spine immobilization on the battlefield. In this population, penetrating cervical cord injury was always fatal and usually immediately so. Only 1.4% of all casualties who were candidates for immobilization might have benefitted from the care. However, the risk of performing immobilization in a hazardous environment is substantial since about 10% of casualties are incurred while helping other casualties. Mandatory immobilization of all casualties with penetrating neck wounds sustained in an environment hazardous to first aid providers has an unfavorable risk/benefit ratio.

Adult↗

PubMed1989

Slight hysteria.

Explore the source record for details and available documents.

Combat Disorders↗

PubMed1989

USS Franklin and the USS Stark--recurrent problems in the prevention and treatment of naval battle casualties.

Events such as the Falklands War and naval actions in the Persian Gulf have emphasized the unique nature of battle casualty care on warships. The purpose of this paper is to describe two actions which illustrate the problems that a medical officer may confront when a warship sustains battle damage: that of the USS Franklin in March 1945 and that of the USS Stark in May 1987. Although neither ship was sunk, damage was severe and about one-quarter of each ship's crew became casualties. More than three-quarters of the casualties were killed, death being due to blast, fire and smoke inhalation.

Humans↗

PubMed1988

Absence of a tachycardic response to shock in penetrating intraperitoneal injury.

The belief that tachycardia is an early and reliable indicator of shock has recently been challenged. We examined 144 battlefield casualties with penetrating intraperitoneal injury to determine whether patients in shock presented with pulse rates that were significantly more rapid than those in patients not in shock. No differences in mean pulse rates were found when using objective operational definitions of shock. In contrast, the only pulse rate difference was noted when shock was defined on the basis of the surgeon's subjective clinical impression and this was attributed to selection bias. The absence of a tachycardic response in battlefield casualties with penetrating abdominal wounds cannot be taken as an indication that serious injury and significant intraperitoneal bleeding have not occurred. Caution should be exercised when using this parameter as a guide for therapeutic interventions, and further study is indicated to determine whether a similar pattern is seen in civilian practice.

Blood Pressure↗

PubMed1988

The wound profile: illustration of the missile-tissue interaction.

The wound profile was developed at the Letterman Army Institute of Research in order to measure the amount, type, and location of tissue disruption produced by a given projectile, and to present the data in a standardized, easy to understand picture. The entire missile path is captured in one or more 25 X 25 X 50 cm blocks of 10% ordnance gelatin at 4 degrees C. The penetration depth, projectile deformation and fragmentation pattern, yaw, and temporary cavity of the missile in living anesthetized swine muscle are reproduced by this gelatin. Measurements are taken from cut sections of the blocks after mapping of the fragmentation pattern with biplanar X-rays. These data are then reproduced on a life-sized wound profile which includes a scale to facilitate measurement of tissue disruption dimensions, a drawing of the loaded cartridge case before firing, the bullet weight and morphology before and after firing (and calculated percent of fragmentation), and the striking velocity. This technique allows us to determine the wounding character of the projectile without the need for elaborate and expensive high-speed cine and X-ray equipment, or the need for shooting live animals. The method improves our understanding of the wounding process and should lay the groundwork to assure more rational and effective treatment.

Firearms↗

PubMed1988

A reconsideration of the wounding mechanism of very high velocity projectiles--importance of projectile shape.

In 1976 a paper appeared which forecast "significant increases in velocities of projectiles from guns and fragments from warheads." It was postulated that the higher velocity projectiles would cause shallow wounds with wide tissue destruction on the surface--especially when striking velocity exceeded the speed of sound in tissue (about 1.5 km/sec). Other studies have not dealt with projectiles in this velocity range; the conclusions and assumptions stated in this 1976 paper have been quoted by others and accepted as fact. In a previous study, we shot blunt fragments into gelatin, but our findings did not support the proposed hypothesis that temporary cavity shape in tissue changes at velocities above the sonic speed. The temporary cavity becomes larger with increasing velocity but it does not become shallow unless the projectile fragments on impact. In the present study, we shot a series of blunt projectiles into animal tissue at velocities of 764 to 2,049 m/s. The stellate skin and muscle disruption splits from temporary cavity stretch we observed in this study are not apparent on entrance wounds from individual explosive device fragments in the living wounded. We suggest, therefore, that studies using blunt projectiles at striking velocities above 700 m/s are lacking in clinical relevance. We also compared wounds produced by pointed projectiles with those produced by blunt projectiles. The marked difference in wound morphology showed the fallacy of doing a study with blunt missiles and applying conclusions from that study to tissue disruption caused by all projectiles.

Animals↗

PubMed1988