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Biomedical subjects

T L Demmy

Publications and source records attributed to T L Demmy.

At least 19 recordsLinked to original sources
PubMed2001

Laboratory confirmation of clinical heart allograft preservation variability.

BACKGROUND: Previously, we reported survival differences from the national heart transplant registry favoring centers that used intracellular organ preservation solutions. To eliminate center selection bias, we tested some of these solutions in a biventricular working rat heart model to determine their relative efficacy. METHODS: Using 103 Sprague-Dawley rat hearts perfused with modified Krebs-Henseleit buffer, both ventricles functioned with adjustable independent preload and afterload and their pressure-length loops generated load-insensitive measurements of cardiac performance. After 15 minutes of stable function, each heart sustained 180 minutes of cold (4 degrees C) ischemia after a 5-minute perfusion by University of Missouri (UMC), Plegisol, Collins, University of Wisconsin, Custodiol, or Roe solutions. Eighty-two hearts were reperfused and the remainder were used for ATP analyses. RESULTS: Although the extracellular solution Plegisol showed good recovery of traditional hemodynamic values, including developed pressure and cardiac output, intracellular solutions like Roe had superior preservation of load-insensitive indices such as preload recruitable stroke work: Roe (intracellular) 103%+/-13%; Custodiol (intracellular) 96%+/-9%; UW (intracellular) 69%+/-12%; Collins (intracellular) 68%+/-9%; Plegisol (extracellular) 68%+/-7%; and University of Missouri (extracellular) 56%+/-10% (p = 0.04). Furthermore, recovery with intracellular solutions tended to be gradual but more progressive after ischemia in contrast to an early plateau shown by extracellular (p < 0.001). Right ventricular recovery and ATP measurements were similar between groups. CONCLUSIONS: These data support the superiority of certain intracellular preservation solutions and provide evidence that optimal heart organ protection may be difficult to judge clinically using hemodynamic values routinely available to the heart transplant surgeon. Care should be taken to verify the performance of some solutions used in heart organ transplantation.

Analysis of Variance↗
PubMed2001

Tracheostomy: a risk factor for mediastinitis after cardiac operation.

BACKGROUND: We studied whether tracheostomy after coronary artery bypass grafting (CABG) is associated with higher incidence of mediastinitis and mortality, and whether shorter intervals between median sternotomy and tracheotomy are associated with higher incidence of mediastinitis. METHODS: Patients (n = 6,057) undergoing CABG since March 1977 were reviewed. Patients requiring tracheostomy and those developing mediastinitis were identified. Mediastinitis diagnosis required positive culture of mediastinal tissue or fluid. RESULTS: After CABG, 88 patients had tracheostomy performed (1.45%). Seven patients receiving tracheostomy after developing mediastinitis were excluded. Of the remaining 81 patients, 7 developed mediastinitis (8.6%) compared with 44 of 5,969 (0.7%) who did not require tracheostomy (p < 0.001). Mortality in tracheostomy patients was 24.7% (20 of 81) compared with 5.2% in patients not requiring tracheostomy (316 of 5,969; p < 0.001). Patients not developing mediastinitis had tracheostomy placement an average of 25 days after CABG compared with 18.7 days for those developing mediastinitis (p = 0.141). CONCLUSIONS: Tracheostomy after CABG is associated with increased incidence of mediastinitis and mortality. In this review, the time interval between CABG and tracheostomy was not predictive of mediastinitis. A larger sample size would be required to be confident that there is no correlation.

Aged↗
PubMed1999

Minimally invasive lobectomy directed toward frail and high-risk patients: a case-control study.

BACKGROUND: To compare minimally invasive video-assisted thoracic surgery (VATS) with thoracotomy, cases were matched from a pool of pulmonary lobectomies performed by one surgeon who offered VATS for patients with unfavorable risk factors. METHODS: A thoracotomy case was paired to each of 19 VATS cases by age, sex, lobe, side, and forced expiratory volume in 1 second. Eleven VATS and 5 thoracotomy patients with severe activity impairments or reduced forced expiratory volume in 1 second (< 1.5 L or 50% predicted) were classified as higher risk than the others. RESULTS: Despite more high-risk cases, VATS yielded shorter hospitalizations (5.3+/-3.7 versus 12.2+/-11.1 days, p = 0.02), chest tube durations (4.0+/-2.8 versus 8.3+/-8.9 days, p = 0.06), and earlier returns to full preoperative activities (2.2+/-1.0 versus 3.6+/-1.0 months, p < 0.01). The VATS operations had no intraoperative complications and lasted 229+/-59 minutes. Pain 3 weeks later was dramatically better for the VATS group (none or mild, 63% versus 6%; severe, 6% versus 63%; p < 0.01). Six complications or deaths occurred in each group and were related to forced expiratory volume in 1 second, steroid usage, age, active smoking, and upper lobe resection (p < 0.01). Three VATS deaths occurred only in elderly, performance status 3 patients, with two caused by gastrointestinal-related problems masked by steroid use. CONCLUSIONS: A VATS lobectomy is less painful and may offer faster recovery for the frail or high-risk patient. Further study, particularly of its safety in severely activity-impaired patients, is warranted.

Aged↗
PubMed1999

Centrifugal pumps: description of devices and surgical techniques.

BACKGROUND: Because of simplicity of application, universal access, and low cost, centrifugal pumps are commonly used for short-term mechanical cardiac assist. Indications and techniques for application of this technology continue to evolve. METHODS: The clinical experience with 151 patients undergoing centrifugal mechanical cardiac assist at the University of Missouri-Columbia has been reviewed. We have compared commonly available centrifugal pumping systems in vitro and in vivo for characteristics that might distinguish them. RESULTS: Centrifugal pumps have been found to be well suited for use in surgery on the thoracic aorta, for extracorporeal membrane oxygenation and for postcardiotomy cardiac mechanical assist. Complications associated with centrifugal mechanical assist are predictable and common but potentially can be reduced by improved surgical techniques and anticoagulation strategies. In vitro and in vivo experimentation with available centrifugal pumps reveals nuances characteristic of each of the devices. CONCLUSIONS: All centrifugal pumps presently available are less destructive to blood cellular elements compared with roller pumps. With familiarity, all can function satisfactorily for short-term mechanical assist with no compelling evidence that favors any particular centrifugal pump system clinically available. Centrifugal pumps are ideally suited for left heart bypass during surgery on a thoracic aorta and for short-term application as may be required for postcardiotomy mechanical assist. Centrifugal pump technology should be part of the armamentarium of all cardiothoracic surgeons.

Animals↗
PubMed1998

Multicenter VATS experience with mediastinal tumors.

BACKGROUND: The use of video-assisted thoracic surgery for diagnosis and treatment of mediastinal tumors in a multiinstitution patient population is not well understood. METHODS: We studied 48 cases from Cancer and Leukemia Group B thoracic surgeons. Of 21 men and 27 women, aged 41 +/- 16 years, 22 patients were asymptomatic. In the others, 92% of tumor-related symptoms improved or resolved after treatment. Five tumors involved the anterior compartment, 19 the middle, and 24 the posterior compartment. Diagnoses were typical for each compartment but also included uncommon problems such as superior vena cava hemangioma and a histoplasmosis cyst causing hoarseness. Of the lesions, a biopsy of 12 was done without excision and the rest were excised completely. Fifteen were cystic and 10 were malignant (8 biopsy only). Maximal dimensions were 5.2 +/- 3.3 cm. RESULTS: Operations were briefer for 24 posterior (93 +/- 41 min) than 5 anterior (195 +/- 46 min, p < 0.01) or 19 middle mediastinal tumors (170 +/- 78 min, p < 0.01). Although 96% had vital mediastinal relations, only six open conversions were performed because of bleeding (n = 3), large size, impaired exposure, or rib attachments, and no patient had morbidity beyond that expected for the thoracotomy. Postoperative stay was shorter for the nonconversion group (3.2 +/- 2.8 versus 5.5 +/- 2.1 days, p = 0.05), as was chest tube duration (1.7 +/- 1.4 days versus 3.2 +/- 1.9 days, p = 0.03). There were no postoperative deaths or major complications, but 7 patients had minor complications. During a mean of 20 months of surveillance (range, 1 to 52 months), one cyst recurred (asymptomatic) as did one sarcoma that was excised. CONCLUSIONS: Video-assisted thoracic surgery is a safe technique for benign mediastinal tumors, typically those in the middle and posterior mediastinum.

Adult↗
PubMed1998

Incidence and predictors of supraventricular dysrhythmias after pulmonary resection.

BACKGROUND: Patients undergoing pulmonary resection were evaluated prospectively in an effort to determine the incidence of and predictors for the development of postoperative supraventricular dysrhythmias. Specifically, we wished to test the hypothesis that the incidence of postoperative supraventricular dysrhythmias is dependent on the magnitude of pulmonary resection. METHODS: One hundred sixteen patients undergoing pulmonary resection had continuous Holter monitoring preoperatively, the day of operation, and the second postoperative day, as well as continuous cardiac monitoring throughout hospitalization. Holter interpretation was blinded to extent of resection. RESULTS: Twenty-six patients underwent pneumonectomy, 7 bilobectomy, 47 lobectomy, and 36 wedge resection. Twenty-six patients (22.4%) had supraventricular dysrhythmias, all atrial fibrillation +/- flutter. The incidence of atrial fibrillation with pneumonectomy, bilobectomy, single lobectomy, and wedge resection was 46.1%, 14.3%, 17.0%, and 13.8%, respectively (p < 0.005 pneumonectomy versus others). Overall, 31% of patients having pneumonectomy required pharmacologic therapy for dysrhythmia compared with 16% of patients having lesser resections, (p = 0.03). The peak incidence of onset of atrial fibrillation occurred on postoperative days 2 and 3 and lasted for less than 1 to 7 days, average 2.5 days. The average age of patients with dysrhythmias (64 years) was greater than those without (58 years) (p = 0.039). Thirty pre- and postoperative variables tested were not found to be significant predictors for development of postoperative atrial fibrillation. CONCLUSIONS: Atrial fibrillation occurs commonly after pulmonary resections but is not predictable. Development of atrial fibrillation is not dependent on the magnitude of pulmonary resection but is associated with the procedure pneumonectomy for reasons not elucidated.

Adult↗
PubMed1998

Thoracoscopic sympathectomy: the U.S. experience.

OBJECTIVE: 48 patients underwent TSSYM. Charts of patients undergoing thoracoscopy were reviewed to assess the safety and efficacy of thoracoscopic sympathectomy (TSSYM). DESIGN: A retrospective review was undertaken at four United States medical centers. RESULTS: TSSYM was performed for reflex sympathetic dystrophy in 27 patients, hyperhydrosis palmaris in 15 patients, and Raynaud's upper extremity ischemia and splanchnic pain in 2 patients each. Anesthesia with one lung ventilation was used. 2.9 ports were used per patient and 0.8 chest tubes were placed per patient. All patients underwent resection of the sympathetic chain, usually with a clip along the bottom of the resected chain. Laser, electro-ablation and electroresection were not used by any of the surgeons in his series. The mean length of hospital stay was 1.8 days. CONCLUSIONS: TSSYM is a safe and effective technique for treatment of a variety of thoracic disorders.

Endoscopy↗
PubMed1997

Organ preservation solutions in heart transplantation--patterns of usage and related survival.

Despite experimental advantages for certain heart preservation solutions (HPS), their clinical popularity and related survival are uncertain. We surveyed all active UNOS heart transplant centers to determine their HPS. HPS survival benefits were tested using the UNOS heart transplant registry. Centers used from 1 to 3 types of 167 solutions. Of these formulations, 55.1% were commonly cited solutions. The other (custom) mixtures differed from those usually reported. All solutions were classified as intracellular (I, [Na++] < 70 mEq/L) or extracellular (E, [Na++] > or = 70 mEq/L). Significant variations in solution usage were observed among major regions of U.S. transplant activity (Northeast [NE], Southeast [SE], and West [W], P < 0.001). For example, 62.5% of University of Wisconsin (UW) and 49.3% of "Other" usage occurred in the NE; 75% of Roe and 100% of Collins usage occurred in the SE; and 100% of Krebs and 46% of Stanford usage occurred in the W. Logistic regression analyses of 9401 patients who underwent transplantation from 10/87 to 12/92 showed a reduction in the adjusted one month mortality odds ratio for grafts preserved with I rather than E solutions (0.85, P < 0.05). Compared with the most commonly used solution, Plegisol (20.1% of cases), the following adjusted odds ratios for one-month mortality were observed: UW, 1.09 (ns); Stanford, 0.80 (P < 0.10); Roe, 0.36 (P < 0.001); Collins, 0.82 (ns); Krebs, 0.14 (P < 0.01). Using the same one month comparison with Plegisol, 16.8% of grafts that received Custom-I solutions also fared better (0.75, P < 0.05) than the 21.4% that had Custom-E mixtures (0.91, ns). HPS usage varies greatly and there are regional preferences. There may be early survival benefits for certain intracellular HPS--however, further study is warranted to explore such relationships.

Cardioplegic Solutions↗
PubMed1997

Feasibility of mathematical models to predict success in video-assisted thoracic surgery lung nodule excision.

BACKGROUND: Pulmonary nodules are occasionally difficult to excise using video-assisted thoracic surgery (VATS). METHODS: To predict operative success, mathematical models using preoperative computerized tomography (CT) measurements were tested in 50 consecutive patients who underwent attempted or successful thoracoscopic lung biopsy. Unrelated technical problems resulted in the exclusion of 3 patients. RESULTS: No differences were noted with respect to lobar location, thoracic dimensions, gender, presence of chronic obstructive pulmonary disease, or nodule pathology. The expression S/(D + 1), where S = nodule size (cm) and D = distance (cm) to the nearest visceral pleura, yielded significantly higher values for visible nodules (P < 0.001). Resectable nodules had a higher score using the expression 1/(S + D + 1), (P < 0.001). Simple cases (n = 19) were defined as those in which nodules were both visible and resectable with very basic VATS techniques. All others (n = 28) were considered complex. The derived expression for Simplicity [1/(S(D + 1))] yielded significantly higher values for simple cases (0.8 +/- 0.3 vs. 0.3 +/- 0.2 cm(-2), P < 0.001) and all simple cases had a score > or = 0.4. Logistic regression analysis showed that the formulas for resectability and simplicity were significant independent predictors for resectability and simplicity. CONCLUSIONS: Equations based on objective CT measurements may be useful for planning VATS nodulectomy or studying the outcome of these minimally invasive operations.

Feasibility Studies↗
PubMed1996

Post-transcriptional regulation of extracellular matrix metalloproteinase in human heart end-stage failure secondary to ischemic cardiomyopathy.

Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the failing heart. To examine whether the MMP activation was due to gene and/or post-translational modification, we analysed tissue from 10 explanted hearts due to coronary heart disease (CHD) and five normal left atrial tissue from donor hearts. Based on in situ immunolabeling MMP-1, tissue inhibitor of metalloproteinase (TIMP-1) and collagen were co-localized in the interstitial tissue. Based on sandwich ELISA, TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue (P < 0.01) and 12 +/- 5 ng/mg and 75 +/- 11 ng/mg in the infarcted tissue (P < 0.01), respectively. These levels suggest repression of TIMP-1 during myocardial infarction. Northern blot analysis indicated that the mRNAs for both MMP-1 and TIMP-1 were increased three-to four-fold in the infarcted tissue as compared to the normal tissue, suggesting upregulation of MMP and TIMP gene transcription following infarction. Based on in situ tissue overlay zymography, the generalized activation of MMP was observed in the interstitium of the infarcted heart. Zymographic and immunoblot analysis demonstrated the presence of one band at 66 kDa (MMP-2) in the normal tissue and several bands at 92 (MMP-9), 66 (MMP-2) and 54 kDa (MMP-1) in the infarcted heart. Incubation of the zymographic gel with metal chelator (phenanthroline) abolished bands at 92 kDa and 54 kDa but phenanthroline did not abolish the lytic band at 66 kDa. The 66 kDa band was completely abolished in the presence of phenanthroline and phenyl methyl sulfonyl fluoride (PMSF). 2D-zymographic analysis suggested that the lytic band at 66 kDa was a mixture of two neutral proteinases with different isoelectric point. Plasminogen/gelatin zymographic analysis of infarcted tissue extract indicated that the band at 66 kDa was plasmin generated due to increased expression of tissue plasminogen activator (tPA) activity. In relation to increased expression of gelatinase in the infarcted tissue, our data suggest that gelatinase B (92 kDa) is induced in diseased heart. The results suggest that tPA converts plasminogen to plasmin which, in turn, activates MMPs and inactivates TIMP-1 post-translationally following ischemic cardiomyopathy.

Cardiomyopathies↗
PubMed1996

Use of centrifugal pumps for postcardiotomy ventricular failure: technique and anticoagulation.

BACKGROUND: Centrifugal pumps have been employed most commonly for postcardiotomy mechanical support after intraaortic balloon pumping has failed. Despite their effectiveness in some patients, morbidity remains high. METHODS: Our clinical experiences with centrifugal pumps were reviewed with particular attention to common morbidity such as bleeding, coagulopathy, and thromboembolism. Evolution of cannulation techniques and anticoagulation strategies were defined. Morbidity during early and more recent experience was compared. RESULTS: Deranged coagulation and excessive mediastinal bleeding were commonly observed in patients undergoing centrifugal mechanical assist for postcardiotomy cardiogenic shock. Evolved strategies to reduce blood loss included meticulous cannulation techniques, early use of blood components, and an aggressive policy of mediastinal reexploration. Thromboembolism occurred with centrifugal mechanical assist, was underestimated by clinical events, and dictated pursuit of improved anticoagulation strategies and device refinement. A clinically significant trend of decreasing morbidity from early to recent experience was observed. CONCLUSIONS: Increasing clinical experience with centrifugal mechanical assist appears to result in a clinically relevant decrease in morbidity.

Anticoagulants↗
PubMed1996

Lung carcinoma-M0. Patterns and results of radiotherapy of all patients referred to one department.

All patients with M0 carcinoma of the lung regardless of the histology, exclusive of Pancoast tumors referred to the same radiation oncology team from 1988 to 1992 were identified. They were 101 patients; 16 of whom were postoperative. To determine the patterns of radiation therapy and results, these cases were analyzed according to the radiation dose and volume irradiated. Fifteen patients had no or futile dose of radiation because of poor general condition. No prophylactic radiotherapy was intentionally given to the supraclavicular area. Relief of symptoms occurred in 87% of symptomatic, evaluable patients. Distant metastases developed in 20% of patients. There were no local recurrences in the nonirradiated supraclavicular or prophylactically irradiated mediastinal areas. Increasing the dose to the primary tumor from 6,000-6,500 to 6,600-7,000 cGy (180-200 cGy/fraction) was tried in a small number of patients with encouraging results.

Aged↗
PubMed1996

A calf model for left ventricular centrifugal mechanical assist.

The increased use of centrifugal mechanical assist (CMA) for treatment of refractory postcardiotomy cardiogenic shock highlights the need for experimental testing to improve clinical results. This report describes the preoperative conditioning, anesthetic and surgical technique, and postoperative management of a reliable calf model refined in this laboratory for in vivo subchronic (96 h) testing of CMA. Holstein bull calves (2 to 3 months old; mean body weight, 78 kg; n = 35) were instrumented for left ventricular CMA; 4 of these calves were sham-operated controls. Anesthetic recovery and postoperative restraint were accomplished in a specially designed crate to which each calf was preconditioned extensively. Younger calves were more readily conditioned and more tolerant of postoperative restraint than older calves. One calf died of ventricular fibrillation intraoperatively. One calf that had been heparinized developed uncontrollable hemothorax and died 12 h postoperatively. One calf prematurely dislodged his aortic cannula 15 h postoperatively and exsanguinated. Six calves developed pelvic limb paresis or paralysis because of lumbar spinal cord thromboembolism by 36 h postoperatively, and 3 of these calves were sacrificed by 42 h postoperatively. Fifteen calves required sedation in the first 12 h after the operation. Tachycardia associated with bottle feeding occurred in 15 calves. Second-degree atrioventricular block was noted frequently during deep relaxation. Postmortem examination demonstrated the absence of surgical wound and distant infection, security of cannulae in all but the calf that prematurely dislodged the aortic cannula, absence of thrombus formation at cannulation sites, and presence of thromboembolism in 51% of the calves. The incidence of thromboembolic lesions was not influenced by the need for chemical restraint, by the occurrence of feeding-associated tachycardia, or by the presence of atrioventricular block. There were no thromboembolic lesions in any of the sham-operated controls.

Anesthesia↗
PubMed1996

Improved method for deep thoracoscopic lung nodule excision.

Minimally invasive excision of deep lung nodules can be difficult partly because endoscopic staplers do not open wide enough. We describe a method in which a standard atraumatic straight clamp compresses the lung to allow placement of the stapler without difficulty.

Humans↗
PubMed1995

Mediastinal histoplasmosis presenting with esophageal involvement and dysphagia: case study.

Esophageal involvement with histoplasmosis is uncommon, but has been recognized in two clinical settings. Most commonly, the esophagus becomes involved as a result of contiguous mediastinal lymphadenopathy. Such patients usually present with dysphagia secondary to midesophageal compression or stricture. The esophagus can also be involved in cases of disseminated histoplasmosis. Esophageal ulcers or nodular lesions are the usual clinical manifestations in this setting. We report a case of mediastinal histoplasmosis with esophageal narrowing and mucosal ulceration that presented with dysphagia. The diagnosis was established at thoracotomy by the histologic finding of necrotizing granulomas and a positive fungal stain. The case was successfully treated with amphotericin B. The literature on esophageal and gastrointestinal histoplasmosis is reviewed.

Adult↗
PubMed1995

Improving clinical outcome with centrifugal mechanical assist for postcardiotomy ventricular failure.

Between October 1986 and May 1994, 65 patients undergoing cardiac surgery required centrifugal mechanical assist devices to separate from cardiopulmonary bypass. This experience was arbitrarily divided into early (n = 33) and recent (n = 32) groups for the purpose of comparing trends in morbidity and mortality. The incidence of mechanical assist application decreased from 2.19% in the early group to 0.96% in the recent group (p < 0.0001). Ability to wean patients from centrifugal assist increased from 33% in the early group to 53% in the more recent group, and hospital survival increased from 15 to 28%. The median chest tube drainage during the first 24 h decreased from 3,245 ml to 1,535 ml, and the incidence of renal failure decreased from 39.4% and 18.8% in the more recent group. Clinically relevant improvement in patient outcome following application of centrifugal mechanical assist for postcardiotomy ventricular failure is being observed.

Adult↗