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Biomedical subjects

T N Masters

Publications and source records attributed to T N Masters.

At least 37 records · Page 2Linked to original sources
PubMed1981

The embolization of bone wax from sternotomy incisions.

We discuss our study on the effects of discontinuation of the usage of bone wax as a hemostatic agent in sternotomy incisions. In 1976, we abandoned use of bone wax because it was suspected of causing several cases of Mycobacterium fortuitum sternal osteomyelitis. In a retrospective study involving 400 patients, we found that this step did not increase postoperative bleeding as measured by drainage from the chest tube and by the need to return patients to the operating room because of bleeding. It also was observed that there was an appreciable simultaneous drop in pulmonary complications. To test our theory that the wax pressed into the bone marrow can embolize to the lung, radioactively tagged bone wax was pressed into the cut sternum in animal models, and a search was made for radioactive deposits in the peripheral lung tissue. Shortly after the application of the wax, there was evidence of large radioactive deposits in the lungs. It is probable that this embolization occurs also under clinical conditions and may play a role in pulmonary complications following open-heart operations.

Animals↗
PubMed1978

Electrophysiologic effects of partial coronary flow reduction in the exposed canine heart. Effects of ischemia and ischemic-induced regional hypothermia on refractoriness and conduction delay.

In the open-chested dog, coronary flow reduction results in a decrese of regional myocardial temperature (T). We assessed the contribution of T decrease to changes in refractoriness and conduction delay attributed to ischemia. The independent effect of regional hypothermia on effective refractory period (ERP) was a linear function of the temperature (ERP = -b T +a) with a -r = 0.97 0.02 in 11 dogs. The effect on conduction time of a ventricular premature beat was a linear function of the dog T at both endocardium (-r = 0.95 +/- 0.02) and epicardium (-r = 0.96 +/- 0.01). A 75% reduction in coronary flow resulted in a mean T decrease of 1.0 +/- 0.3 degrees C. The T decrease was sufficient to mask the effects of ischemia on shortening of the ERP. Furthermore, the conduction delay of ventricular premature beats during 75% coronary flow reduction could be accounted for by the decrease in T alone in five of seven dogs. We conclude that changes in refractoriness and conduction during acute coronary flow reduction in the open-chested dog are due to the composite effects of ischemia and the decrease in regional temperature. The open-chested model may have important limitations in understanding the electrophysiologic effects of acute coronary insufficiency. However, it may have important applications in defining the electrophysiologic environment at the time of coronary artery surgery.

Animals↗
PubMed1978

Mycobacterium fortuitum epidemics after open-heart surgery.

We present the clinical and epidemiological features of Mycobacterium fortuitum epidemics involving 19 patients who underwent open-heart surgery. The source of the infection could not be identified. However, bone wax and homografts utilized at that time have been suspected. The infected patients responded poorly to antibiotic management and their courses in most cases were influenced beneficially by total sternectomy and transplantation of the omentum into the mediastinum. The emergence of M. fortuitum may represent an aggressive bacterial strain resistant to presently used broad-spectrum antibiotic drugs.

Adult↗
PubMed1978

The application of thermography in the study of coronary blood flow.

The technique presented in this paper is based on the authors' previous observations in which they found that artificial decrease of blood flow to a portion of the heart muscle leads to an immediate and proportional drop in the regional myocardial temperature. It appeared to the authors as a logical next step to apply the thermographic camera to a monitor and to record such changes in the human patient during coronary surgery and to use the data to draw conclusions applicable to regional blood supply and to blood flow through surgically inserted vein grafts. They found that, on the normothermic heart, there were well-identifiable "cold" patches corresponding with areas of impaired coronary circulation. By infusion of blood to the ischemic myocardium through individual release of the bypass grafts, the thermogram responded by immediate appearance of "warm" spots corresponding with the areas supplied by the grafts. Even more dramatic demonstration of graft patency and outline of the area supplied by the graft could be performed by injecting cold saline solution into the grafted saphenous veins. In the author's experience this most interesting new method proved to be a useful tool in coronary surgery both as an adjunct in delineating ischemic areas and in proving the patency and efficiency of the grafts inserted.

Blood Flow Velocity↗
PubMed1977

Three years' experience with computer-based intensive care of patients following open heart and major vascular surgery.

The authors present their experiences with the Roche-5000 Computer-Based Intensive Care System in the management of 100 consecutive patients who have undergone open heart or major vascular surgery. The system performs the following junctions: (1) numerical and graphic display, out-of-limits alarms, storage and printout of 12 biological and surgical parameters, including chest drainage and urine output, by on-line direct monitoring; (2) display, storage, and printout of all additional laboratory and clinical data by manual input; (3) automatic demand-regulated transfusion and infusion program; (4) a program of medical logic, which includes situation analysis based on the above, two way dialogue with the computer, treatment recommendations to the physician, selective nursing and laboratory orders, acid-base analysis, and instructions for respirator setting. It was found that the computer-monitored patients recovered faster and smoother, with fewer fluctuations in the measured parameters and fewer postoperative complications than did those treated by conventional methods. One additional important effect of the system was that the nurse, relieved of the mechanical tasks of measuring, charting, and recording, was left with a greater amount of time for the care of the patient's personal needs. It seems ironic that such a technical advancement in electronics not only made the recovery faster and safer but also created a more humanistic approach in patient care, through better application of basic nursing techniques.

Cardiac Surgical Procedures↗
PubMed1976

Beneficial metabolic effects of methylprednisolone sodium succinate in acute myocardial ischemia.

The metabolic and hemodynamic effects of methylprednisolone sodium succinate (40 mg/kg body weight) after acute myocardial ischemia were determined in 24 heparinized mongrel dogs. Myocardial ischemia was produced by ligation of the left anterior descending coronary artery. Catheters in the coronary sinus and the vein draining the left anterior descending coronary arterial area were used to collect blood samples from nonischemic and ischemic myocardium. Lactate, pyruvate, glucose, free fatty acids and oxygen were measured in arterial and venous blood from ischemic and nonischemic areas before and 3, 30 and 60 minutes after myocardial ischemia in animals with (Group II) and without (Group I) steroid treatment. In both Groups I and II glucose, lactate, free fatty acids, oxygen and coronary blood flow in nonischemic areas were not significantly changed, whereas glucose uptake in ischemic areas was significantly increased with myocardial ischemia and remained elevated. In Group I lactate uptake in ischemic areas became negative after coronary arterial ligation and remained so; in Group II, it increased after 30 (70%) and 60 (111%) minutes. Free fatty acid uptake in ischemic areas was reduced after myocardial ischemia in Group I, but in Group II it increased after 30 (224%) and 60 minutes (173%), and there was a concomitant increase in oxygen uptake. Pyruvate uptake in nonischemic areas decreased after 60 minutes in Group I, whereas it was reduced after 30 (68%) and 60 minutes (513%) in Group II. The changes were similar in ischemic myocardium. There were no significant changes in hemodynamic indexes. Coronary blood flow in ischemic areas decreased in Group I after myocardial ischemia and further after 30 and 60 minutes, but in Group II it increased after 30 (82%) and 60 minutes (53%). The data indicate that administration of methylprednisolone results in improved collateral blood flow into the infarcted area and a significantly improved metabolic response of ischemic myocardium. The glucocorticoid may also have a direct benefical effect on carbohydrate metabolism and cause the increased pyruvate neccesary to maintain the generation of energy-producing substrates. The results also suggest that methylprednisolone increases cell survival time and results in greater salvage of ischemic myocardium.

Acute Disease↗