Operation Joint Endeavor in Bosnia: telemedicine systems and case reports.

OBJECTIVE: For the last several years the U.S. Department of Defense (DoD) has operated a telemedicine test bed at the U.S. Army Medical Research and Material Command's Medical Advanced Technology Management Office. The goal of this test bed is to reengineer the military health service system from the most forward deployed forces to tertiary care teaching medical centers within the United States by exploiting emerging telemedicine technologies. METHODS: The test bed has conducted numerous proof-of-concept telemedicine demonstrations as part of military exercises and in support of real-world troop deployments. The most ambitious of those demonstrations is Primetime III, an ongoing effort to provide telemedicine and other advanced technology support to medical units supporting Operation Joint Endeavor in Bosnia. RESULTS: Several of the first instances of the clinical use of the Primetime III systems are presented as case reports in this paper. These reports demonstrate capabilities and limitations of telemedicine. CONCLUSION: The Primetime III system demonstrates the technical ability to provide current telecommunications capabilities to medical units stationed in the remote, austere, difficult-to-serve environment of Bosnia. Telemedicine capabilities cannot be used without adequate training, operations, and sustainment support. Video consultations have eliminated the need for some evacuations. The system has successfully augmented the clinical capability of physicians assigned to these medical units. Fullest clinical utilization of telemedicine technologies requires adjustment of conventional clinical practice patterns.

A quality assurance model of operative mortality in coronary artery surgery.

Quality assurance in coronary artery bypass grafting (CABG) surgery requires a comparison of operative mortality against an accepted standard of care. Raw mortality statistics are unacceptable in this context, and risk factor analysis is essential. However, this principle has not been adequately demonstrated in previous reports. Our goal in this study was to develop a risk model of accepted CABG mortality and illustrate its proper use in coronary artery surgery. The model was derived from a Bayesian analysis of 6,630 patients undergoing CABG in the Coronary Artery Surgery Study (CASS) registry. Age, sex, ventricular function, previous myocardial infarction, extent of coronary artery disease, unstable angina, and surgical priority were used by the model to sort patients into risk categories. From January 1984 through December 1987, 840 patients underwent isolated CABG at our hospital. With raw mortality data, the 3.9% (33/840) mortality of our patients was significantly different from the 2.3% (153/6,630) CASS mortality (p less than 0.001). When our patients were entered into the CASS model for risk stratification, however, our CABG mortality conformed to the CASS experience. These results illustrate the fallacy of using raw mortality statistics for interinstitutional comparisons. This type of risk model is a fundamental element of CABG quality assurance.

Use of a Bayesian statistical model for risk assessment in coronary artery surgery.

A computerized statistical model based on the theorem of Bayes was developed to predict mortality after coronary artery bypass grafting. From January, 1984, to April, 1987, at our hospital, 700 patients underwent isolated coronary artery bypass grafting. The presence or absence of 20 risk factors was determined for each patient. The first 300 patients formed the initial database of the Bayesian predictive model, and the remaining 400 patients were prospectively evaluated in four groups of 100 each. Each group was prospectively evaluated and then incorporated into the database to update the model. There was good agreement between predicted and observed results. Bayesian theory is particularly suited to this task because it (1) accommodates multiple risk factors, (2) is tailored to one's specific practice, (3) determines individual, rather than group, prognosis, and (4) can be updated with time to compensate for a changing patient population. These flexible attributes are especially valuable in light of recent changes in the coronary artery bypass graft patient profile.

Serum creatine kinase and lactate dehydrogenase isoenzyme levels in patients after major esophageal surgery, esophageal dilation, and acute myocardial infarction.

All three isoenzymes of creatine kinase (CK), including MB, the fraction used in diagnosing acute myocardial infarction (AMI), have been found in the esophagus. Clinical reports suggest that injuries to the esophagus can cause changes in peripheral serum CK. This prospective study was designed to delineate whether esophageal dilation or major esophageal surgery would cause changes in serum CK and lactate dehydrogenase isoenzymes that might be consistent with the diagnosis of an AMI. Two groups of patients admitted to a coronary care unit were used as controls: patients with electrocardiographically proved AMI and those who had chest pain but who had AMI ruled out by sequential electrocardiograms. The coronary care unit patients had serum enzymes determined on admission, then every 8 hours for four samples, and then daily for 3 days. The surgical patients had determinations preoperatively, in recovery, every 8 hours for four samples, and daily for 5 days. The patients who had esophageal dilations had serum enzyme levels drawn before the procedure and every 8 hours for 2 days after dilation. Serum total CK and lactate dehydrogenase levels were determined by automated spectrophotometry. Isoenzyme levels were determined by agarose gel electrophoresis. The data suggest that small serum CK-MB bands that may be generated by esophageal surgery or dilation can be differentiated from those seen in AMI and that AMI can be confirmed by simultaneous analysis of serum lactate dehydrogenase isoenzymes.

Prevention of ventricular fibrillation after myocardial revascularization.

Ventricular fibrillation during reperfusion after aortic cross-clamping for coronary artery bypass grafting may cause subendocardial injury. We investigated the use of lidocaine to prevent ventricular fibrillation during this period. In a blind, prospective, randomized trial, 91 consecutive patients undergoing elective coronary artery bypass graft procedures were given lidocaine (2 mg/kg) or normal saline immediately before removal of the aortic cross-clamp. The groups were similar with respect to demographic, clinical, and intraoperative variables. Myocardial preservation techniques were similar in both groups. Of 47 patients receiving lidocaine, 38 recovered a supraventricular rhythm without ventricular fibrillation, compared with only 5 of 44 patients in the control group (p less than .001). When ventricular fibrillation occurred, patients in the control group required a greater number of direct-current countershocks (2.31 versus 1.86) to convert to sinus rhythm. Transient heart block, requiring temporary pacing, developed in 3 patients in the lidocaine group, compared with 1 patient in the control group. There was no significant difference between the groups in the requirement for perioperative inotropic support (6 of 47 versus 6 of 44) or the number of myocardial infarctions (2 of 47 versus 1 of 44), and there were no deaths in either group. Lidocaine infusion immediately before removal of the aortic cross-clamp significantly reduces the incidence of ventricular fibrillation during the reperfusion period after cardiopulmonary bypass.

Changes in serum creatine kinase and lactate dehydrogenase caused by acute perioperative myocardial infarction and by transatrial cardiac surgical procedures.

A prospective clinical study was conducted to ascertain if a patient's postoperative elevation in serum creatine kinase MB isoenzyme coupled with determination of the lactate dehydrogenase1/lactate dehydrogenase2 ratio could differentiate whether atrial or ventricular myocardium was the source of these changes. Animal studies have shown that atrial myocardium is as rich a source of creatine kinase MB as is ventricular myocardium. Atrial myocardium has a lactate dehydrogenase1/lactate dehydrogenase2 ratio less than 1.00, whereas in ventricular myocardium the ratio is greater than 1.00. Sixty-four patients were assigned to six groups on the basis of serial electrocardiograms and vectorcardiograms by a cardiologist who was unaware of their clinical courses. The control group (Group 1) consisted of 16 patients admitted to the coronary care unit who had no electrocardiographic changes. Three surgical groups without electrocardiographic or vectorcardiographic evidence of perioperative myocardial infarction were studied: 10 patients undergoing routine coronary artery bypass procedures (Group 2), six adults undergoing repair of secundum atrial septal defect (Group 3), and 13 patients having mitral valve replacement (Group 4). Two groups of surgical patients who had acute perioperative transmural myocardial infarctions confirmed by serial electrocardiograms and vectorcardiograms were studied: 15 patients (Group 5) who had elective coronary artery bypass procedures and four (Group 6) who had mitral valve replacement. This study suggests that serum creatine kinase MB levels in excess of 50 IU/L on the postoperative day 1 and day 2 samples coupled with serum lactate dehydrogenase1/lactate dehydrogenase2 ratios greater than 1.00 on the postoperative day 2 and day 3 samples support the diagnosis of acute myocardial infarction. Patient groups undergoing procedures necessitating atriotomies had average elevations in serum creatine kinase MB and in the lactate dehydrogenase1/lactate dehydrogenase2 ratio, but these were significantly less than those seen when acute perioperative myocardial infarction had occurred.

The use of computed tomography in the evaluation of mediastinal masses.

A retrospective analysis was conducted to ascertain whether computed tomography had increased diagnostic accuracy while decreasing the number of tests needed in the preoperative assessment of patients with mediastinal masses. A total of 42 patients were entered into the study: Fifteen patients were evaluated before the advent of computed tomography (No CT) and 27 patients had computed tomography during their evaluation (CT). The No CT group comprised 10 male and five female patients (2:1 ratio); the age range was 8 months to 61 years. The CT group included 15 male and 12 female patients (1.25:1.0 ratio), the age range being 21 to 70 years. In each group, both invasive and noninvasive studies were done. Although the CT group had 40 noninvasive tests, 27 were computed tomographic scans. The additional 13 noninvasive tests and the five invasive tests added no significant diagnostic information. In the No CT group, preoperative evaluation as to the cystic or solid nature of the mass was correct only four of 13 times (31%). In the CT group, 22 of 25 patients had accurate assessment as to the cystic or solid nature of the lesions (88%). In addition, extension of the mass into other structures, consistent with malignancy, was correctly diagnosed preoperatively in nine of the patients in the CT group. Two had extension of the mass at operation not preoperatively diagnosed (82% accuracy). None of the No CT group was given an assessment of possible mass extension preoperatively. The results suggest that mediastinal masses can be evaluated by computed tomography with a high degree of accuracy for predicting the nature, size, location, and involvement of other organs by the mass. The use of other tests before resection generally yields little additional information.

Evaluation of serum creatine kinase and lactate dehydrogenase in experimental myocardial infarction, atriotomies, and thoracotomies.

Myocardial infarction causes elevation of the serum myocardial-associated isoenzyme of creatine kinase (CK-MB) and a serum isoenzyme of lactate dehydrogenase (LDH1). Since atrial myocardium has as much CK-MB as ventricular myocardium, surgical manipulation of the atrium could cause elevation of serum CK-MB in the postoperative period. The distribution of LDH isoenzymes is different between atrial and ventricular myocardium. Hence, surgical procedures on the atrium could, theoretically, cause different changes in serum LDH isoenzymes than those seen after acute myocardial infarction. This study was conducted to ascertain whether surgical manipulation of the atrium could cause changes in these two serum enzyme systems that might be confused with those seen after acute myocardial infarction. Right thoracotomies were performed on 20 dogs. Each dog then was assigned randomly to one of four groups: thoracotomy (control), placement of atrial pursestring sutures, atriotomy, or acute perioperative myocardial infarction. Serum total and isoenzyme distributions of CK and LDH were measured for 48 hours in all animals. The results suggest that significant elevations of serum CK-MB occurred even after small atriotomies. Confirmation of a ventricular myocardial origin of postoperative serum CK-MB bands was obtained by analysis of serum LDH isoenzymes in that the ratio of LDH1 to LDH2 and the absolute value of serum LDH1 became elevated only after acute perioperative myocardial infarction and not after atriotomy.

Rib fracture healing in experimental flail chest.

Sixteen dogs were placed under general anesthesia and flail segments of the left chest were created by transecting ribs 7,8,9, and 10 anteriorly and posteriorly. Fractures were 10 cm apart so that a 10-cm flail segment encompassing four ribs was created. In Group I, the control (N = 5), the chest wall muscles were closed without any stabilization of the fractures. Group II (N = 5) had stabilization of both anterior and posterior fracture sites by polypropylene sutures. Group III (N = 6) had stabilization of the fractures in ribs 7 and 8 with 2.5-cm bone grafts taken from the left fourth rib. Ribs 9 and 10 were stabilized by polypropylene sutures. The study established a canine model for flail chest. It also showed that strut stabilization of rib fractures with bone grafts promotes better healing than suture stabilization. It suggests that using bone grafts taken from another rib to stabilize flail segments may be unsatisfactory since the rib used as a donor showed no signs of regeneration at 30 days.

Creatine kinase and lactate dehydrogenase in the muscles encountered during median sternotomy and in the myocardium of the cardiac chambers.

The validity of using creatine kinase MB and lactate dehydrogenase serum isoenzymes to confirm the diagnosis of perioperative myocardial infarction in patients who have had cardiac operations has been questioned, since both have been detected in skeletal muscles. Little is known concerning the concentration of either isoenzyme in the muscles routinely encountered during median sternotomy. Since we have previously shown that the dog is an adequate model in which to study creatine kinase and lactate dehydrogenase isoenzymes, eight healthy dogs were placed under general anesthesia and 1 gm blocks were resected from selected muscles (intercostals, rectus abdominis, diaphragm, and sternothyroid) and from the walls of all four cardiac chambers. Each 1 gm block was homogenized individually in Ringer's lactate, centrifuged, and the supernatants were analyzed for total creatine kinase and lactate dehydrogenase activity by spectrophotometry. Isoenzymes were determined by agarose gel electrophoresis. The study shows that the chest wall muscles and atrial myocardium have appreciable quantities of creatine kinase MB. Hence, serum creatine kinase MB bands in the perioperative period can be generated by manipulation of chest wall muscles and the atrial wall as well as by infarction of the ventricular myocardium.

A longitudinal evaluation of thyroid function in critically ill surgical patients.

Thyroid hormone alterations (known as the "sick-euthyroid syndrome") are common following major surgery, but the time course for appearance and recovery from these alterations has not previously been longitudinally studied in a large group of surgical patients. The authors prospectively studied 59 patients undergoing major surgery (coronary artery bypass grafting, pneumonectomy, or subtotal colectomy). Compared with preoperative values, the mean serum T4, T3, free T3, and TSH concentrations decreased significantly (p less than 0.05) following surgery. Serum reverse T3 and T3 resin uptake index increased, while free T4 levels remained unchanged. These changes were seen within 6 hours of surgery and normalized by 1 week after surgery. Although the serum TSH response to TRH was normal before and after surgery in 56 of the 59 patients, the maximal TRH-induced increase in serum TSH and the integrated serum TSH response to TRH were suppressed in the early perioperative period. This postoperative TSH suppression correlated with elevated postoperative plasma dopamine concentrations (r = 0.57, p less than 0.05). Three patients with compensated primary hypothyroidism were detected in the study and represent the first documentation of serial thyroid hormone and TSH levels in hypothyroid patients undergoing major surgery. These patients had similar changes in thyroid hormone values compared with euthyroid patients. The serum TSH response to TRH was suppressed into the normal range in two of these patients on the day following surgery. The authors conclude that the sick-euthyroid syndrome occurs within a few hours of major surgery and remits with convalescence. Postoperative decreases in serum TSH may mask the diagnosis of hypothyroidism. Surgical consultants should be aware of these rapid postoperative changes so that thyroid function tests are properly interpreted in patients who have undergone major surgery.

Radiation associated malignancies of the esophagus.

This report documents the experience of the authors with two patients who had received thoracic radiation for disseminated teratocarcinomas of the testis, survived their malignancies, and subsequently developed squamous cell carcinomas of the esophagus. To the authors' knowledge, only 11 other cases of esophageal malignancies arising in patients who had received previous mediastinal irradiation have been reported in the world literature. With increasingly successful mediastinal radiation for malignant disease resulting in prolonged patient survival, an increasing number of such patients with subsequent esophageal malignancies can be anticipated. Close follow-up of patients receiving radiation therapy to periesophageal tissues is recommended, and prompt evaluation of any symptoms of esophageal dysfunction is indicated.

Diagnostic dosages of protirelin (TRH) elevate BP by noncatecholamine mechanisms.

While performing thyroid function tests, we noticed that protirelin (TRH) raised BP, and, therefore, we investigated the effect of diagnostic dosages of protirelin (500 micrograms) on plasma catecholamine levels and cardiovascular function in eight patients one day before, one day after, and four weeks following heart surgery. Mean arterial pressure (MAP), heart rate (HR), plasma norepinephrine (NE), epinephrine (EPI), dopamine (DA), thyroid hormone (triiodothyronine [T3], thyroxine), and thyrotropin (TSH) levels were measured before and after the intravenous injection of protirelin. Protirelin increased MAP transiently from 88 +/- 2 to 103 +/- 3 mm Hg (before surgery), 86 +/- 4 to 102 +/- 4 mm Hg (one day after surgery), and 86 +/- 4 to 104 +/- 5 mm Hg (four weeks after surgery). There were no notable changes in HR or plasma NE, EPI, or DA levels. The T3 and TSH response to protirelin was normal on all three study days. Protirelin raised MAP by an effect on systemic vascular resistance (SVR) rather than an increase in cardiac output. We conclude the following: (1) diagnostic dosages of protirelin transiently elevate MAP and SVR by a noncatecholamine mechanism, (2) clinicians who perform protirelin tests should be aware of protirelin's transient pressor effects.

Adult human saphenous vein endothelial cells: assessment of their reproductive capacity for use in endothelial seeding of vascular prostheses.

Autogenous endothelial seeding (AES) of vascular prostheses (VP) using venous endothelial cells (EC) reduces platelet-VP interactions and improves patency rates in small caliber VP in dogs. To conserve patients' veins for use in coronary or limb bypass surgery, human trials of AES should require proof that adequate numbers of EC with the growth capacity to cover VP can be harvested from acceptably small pieces of peripheral vein. EC were isolated from excess saphenous vein segments remaining after coronary bypass surgery by filling veins with 0.1% CLS II collagenase at 37 degrees C for 15 min and removing EC by flushing the veins with culture medium. EC were cultured on fibronectin-coated dishes in medium 199 with 30% human serum and 300 micrograms/ml of endothelial cell growth factor. These cells grew to form confluent monolayers, and were identified as EC by tests for factor VIII antigen. Veins from 53 patients with a mean age of 55.8 +/- 9.8 (SD) years yielded vein segments with an average area of 1.9 +/- 0.6 cm2, from which an average of 5.3 +/- 2.8 X 10(4) cells were removed per cm2 of vein area. EC in culture underwent 14.3 +/- 1.4 population doublings with an average population doubling time of 1.8 +/- 0.3 days (N = 14 cultures), which allowed an 100-fold increase in cell number to occur in 11 to 12 days. These data suggest that the EC available from small vein segments in adult humans have the growth capacity to cover areas comparable in size to the luminal areas of VP commonly used in arterial surgery.

Cystic lesion of the thymus. An occasionally malignant cervical and/or anterior mediastinal mass.

Between 1965 and 1982, we treated 46 patients with cystic lesions of the thymus. Thirty patients had anterior mediastinal cysts, nine had cysts which were large enough to be both cervical and mediastinal, and seven had cervical cysts. The majority (40/46) presented with asymptomatic masses. Six patients presented with distinct complaints: dysphagia (four patients), hoarseness owing to vocal cord paralysis (one patient), and cervical pain (one patient). All six had benign thymic cysts. The diagnosis of a cystic mass was established prior to operation by ultrasonography and computed axial tomography in our last three patients. These two techniques delineated the capsule and the central fluid in those three cases. All 46 patients had the mass resected without mortality or significant morbidity, except for resection of the phrenic nerve in one patient with malignant cystic thymoma. Cervical cysts were excised through cervical incisions. Cysts located in the anterior mediastinum and cervical-mediastinal cysts required median sternotomy or right thoracotomy for successful resection. Pathological examination showed that 39 patients had benign thymic cysts, three had benign cystic thymoma, two had malignant thymoma, one had a seminoma arising in the thymus, and one had a lymphoblastoma. We believe that a cystic thymic mass which can be detected by ultrasonography and computed tomography, although usually benign, does not eliminate the possibility of malignancy, and resection, therefore, is indicated.

Management of patients with malignant thymoma.

This report documents the results of therapy in 23 patients treated for malignant thymoma between 1944 and 1979. Of the group, 22 patients had neoplasms which invaded mediastinal structures; six had distant metastases. Four patients had myasthenia gravis and one had erythroid hypoplasia associated with collagen vascular disease. No deaths were associated with primary therapy, which included an operative procedure in all cases. Follow-up ranged from 4 months to 18 years (mean 5.63 +/- 1.03 years, SEM). Fifteen patients died, with postoperative survival times ranging from 4 months to 18 years (mean 3.8 +/- 1.27 years). Five patients were alive without recurrence from 3 to 11 years postoperatively (mean 6.8 +/- 1.36 years), and three patients were alive with recurrence or distant metastases from 4 to 17 years postoperatively (mean 10.75 +/- 2.66 years). Differences in survival on the basis of tumor cell type were not statistically significant. Therapeutic groups were analyzed for 5 year survivors, tumor deaths within 5 years of therapy, deaths due to other causes, deaths due to tumor after 5 years, those presently alive, and longest known survivor. The data suggest that complete surgical excision offers the best chance of long-term survival when compared to partial resection plus irradiation (p less than 0.05). No statistical significance could be demonstrated between the groups who had complete resection with versus without postoperative irradiation. There also was no statistically significant difference between the group of patients receiving irradiation following partial excision of most of their tumor and the group receiving irradiation following only biopsy of the lesion. This observation suggests there is no value in so-called "debulking procedures" and suggests that irradiation may be of value in local control of thymoma. Perpetual surveillance is necessary since late recurrence is common.

Comparison of cephalothin and ceforanide prophylaxis in cardiac surgery with cardiopulmonary bypass.

Eighty-five patients undergoing cardiac surgery with cardiopulmonary bypass were given either cephalothin or ceforanide perioperatively in randomized, blinded fashion. The incidence of surgically related, postoperative infections was 23% for the cephalothin- and 26% for the ceforanide-treated groups. There were no statistically significant differences that could be identified between patients who became infected and those who remained free of infections, although the time spent in the operating theater was longer for the former group. Ceforanide achieves adequate levels in plasma and myocardial tissue that are sustained several hours after a 0.5-g parenteral dose and allows a 12-h interval between doses. Other currently available agents would have to be administered more frequently to achieve similar results.

Relationship of triglyceride levels to thrombosis in patients with coronary artery disease.

The relationship of triglyceride levels to coagulation abnormalities was studied in 43 patients, who were divided into two groups. Group 1 consisted of patients with triglyceride levels less than 200 mg% (range, 75 to 190 mg%), and Group 2 consisted of patients with triglyceride levels greater than 250 mg% (range, 255 to 890 mg%). Analysis of the data revealed that patients with high triglyceride levels also have a high incidence of low antithrombin III activity and increased platelet aggregation. It is likely that hyperlipidemic patients are more prone to thrombosis of diseased coronary arteries or saphenous vein bypass grafts, and should definitely be placed on appropriate anticoagulants.

Initial and long-term results in the management of primary chest wall neoplasms.

One hundred ten patients with primary chest wall neoplasms were analyzed for long-term results. The diagnosis of 59 malignant and 51 benign tumors was confirmed by the Armed Forces Institute of Pathology. No deaths were associated with primary definitive therapy. Among the five most frequently encountered malignant tumor types, five-year survivals were obtained in 9 of 17 (53%) patients with fibrosarcoma, 8 of 9 (89%) patients with chondrosarcoma, 2 of 8 (25%) patients with solitary chest wall plasmacytoma (multiple myeloma), 1 of 6 (17%) patients with Ewing's sarcoma, and 2 of 4 (50%) of patients with osteogenic sarcoma. Although the five-year survival appears to indicate therapeutic success in patients with Ewing's sarcoma and osteogenic sarcoma, patients with chondrosarcoma or fibrosarcoma may have a more protracted course, and those with solitary plasmacytoma usually develop multiple myeloma. The findings suggest that radical surgical excision is the treatment of choice for chondrosarcoma; radical surgical excision combined with chemotherapy, for fibrosarcoma and osteogenic sarcoma; surgical excision combined with radiation and chemotherapy, for Ewing's sarcoma; and systemic surveillance and therapy, for pathologically confirmed solitary plasmacytoma.