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Biomedical subjects

J Theodore

Publications and source records attributed to J Theodore.

At least 19 recordsLinked to original sources
PubMed1992

Cardiac function after domino-donor heart transplantation.

A major limitation in cardiac transplantation is donor availability. A possible way to increase the supply of donor hearts is to use explanted hearts from patients undergoing heart-lung transplantation for primary lung disease. One potential advantage of this approach, termed domino-donor transplantation, is the existence of a donor right ventricle already adapted to pulmonary hypertension, which would therefore theoretically decrease the likelihood of acute donor right heart failure in recipients with preexisting elevation of pulmonary vascular resistance. Potential disadvantages include graft failure secondary to chronic effects of pulmonary hypertension on the right ventricle, arrhythmia and infections. Seven domino-donor transplants were performed at Stanford University Hospital; graft and patient survival to date are 100% at a mean follow-up of 20 months (range 1 to 26). Infection and rejection rates have been comparable to those of the current Stanford experience for conventional orthotopic transplantation. Right ventricular function and size have either improved or remained unchanged in all patients after transplantation. Transient early postoperative donor right ventricular dilation, a characteristic adaptive response seen in nondomino transplants, occurred in 4 patients with pulmonary hypertension before surgery. These data indicate that, with adequate assessment before surgery, domino-donor cardiac transplantation is an appropriate means of augmenting the donor pool.

Actuarial Analysis↗
PubMed1992

Trimethoprim-sulfamethoxazole prophylaxis for Pneumocystis carinii infections in heart-lung and lung transplantation--how effective and for how long?

Pneumocystis carinii pneumonia (PCP) is a common clinical problem in the setting of organ transplantation, particularly in heart-lung and lung allograft recipients. Without prophylactic measurements, the incidence of P carinii pneumonia can reach up to 88% of heart-lung transplant recipients. We conducted a retrospective analysis of the Stanford heart-lung and lung transplant experience in order to assess the efficacy of the prophylactic therapy and to try to define the duration of therapy necessary for prevention. During a 9-year period 82 heart-lung and 13 single-lung transplants were performed. Of the patients not on prophylaxis therapy 27% (13 patients) developed P carinii infection as compared with 0% of patients on trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis. The incidence of PCP infection peaked between 3 and 6 months posttransplantation. No case of infection was observed before the 7th week posttransplant. PCP was more common following induction immunosuppression with OKT3 as compared with RATG (P less than 0.05). All cases of infections later than one year posttransplant were associated with recent increase in the immunosuppression regimen with high-dose corticosteroids for treatment of acute or chronic (obliterative bronchiolitis) rejection. Although our study is retrospective and based on various immunosuppressive and diagnostic technique periods, it seems that TMP-SMX is highly effective in preventing PCP infections in heart-lung and lung transplant recipients. Twelve months of therapy is probably a sufficient length of therapy if immunosuppressive therapy is stable. However, whenever augmentation in the immunosuppression regimen is indicated, prophylactic therapy should promptly be restarted.

Adrenal Cortex Hormones↗
PubMed1992

Detection of inspiratory resistive loads by heart-lung transplant recipients.

Human heart-lung transplantation recipients (HL) are models for the effects of selective lower respiratory tract denervation. We used a series resistor to examine thresholds of inspiratory flow resistance perception among 16 HL in comparison with 15 normal control subjects (C) and 12 heart transplant recipients (H). HL and C were closely age matched. H subjects were older and had mildly reduced lung volumes compared with the other groups. The perception threshold was defined as the added resistance (delta R) detected by subjects at 50% of random, blinded presentations. These delta R were subsequently expressed as a fraction of the airway resistance of the subject and baseline resistance of the apparatus (delta R/Raw + Rapparatus), otherwise known as the Weber fraction. The mean +/- SEM Weber fractions were nearly identical for HL and C (0.32 +/- 0.05 versus 0.34 +/- 0.05, respectively). The Weber fraction of H (0.74 +/- 0.17) was significantly greater than those of both other groups (p less than 0.05 by Kruskal-Wallis test). We conclude that lower respiratory tract afferents do not play a significant role in the perception of inspiratory resistive loads. The finding of an abnormally high Weber fraction in the heart transplant population remains unexplained but may be a function of age or restrictive pulmonary defects.

Adult↗
PubMed1992

Diagnosis of bronchiolitis obliterans in heart-lung transplantation patients: importance of bronchial dilatation on CT.

OBJECTIVE: The purpose of this study was to evaluate the significance of bronchial dilatation identified on high-resolution CT scans obtained after heart-lung transplantation. Bronchial dilatation has been identified on pathologic specimens and on high-resolution CT scans of patients with severe bronchiolitis obliterans after lung transplantation, but this finding has not previously been systematically studied as a manifestation of this complication. MATERIALS AND METHODS: We studied the high-resolution CT scans of 16 patients who had had heart and lung transplantation at least 1 year before, and compared the percentage of dilated bronchi with evidence of small airways disease shown on pulmonary function tests. RESULTS: We found a close correlation between the percentage of bronchi in the lower lobes that were dilated and the percent predicted forced expiratory volume in 1 sec, forced vital capacity, and forced expiratory flow between 25% and 75% of vital capacity. No other feature identified on high-resolution CT scans correlated with pulmonary function abnormalities. CONCLUSION: We conclude that dilatation of the lower lobe bronchi is a good indicator of bronchiolitis obliterans in this population, and that the percentage of dilated bronchi generally increases with increasing pulmonary dysfunction.

Biopsy↗
PubMed1992

Current trends in lung transplantation. Lobar transplantation and expanded use of single lungs.

Heart-lung transplantation remains the only therapeutic option for patients with combined end-stage cardiopulmonary disease. Because of the scarcity of heart-lung donors, we have been investigating other surgical alternatives for patients with end-stage vascular and parenchymal lung disease. From June 1989 through June 1991, 48 patients underwent pulmonary transplantation. Seventeen of the 48 patients underwent single lung transplantation. Of the 17 patients in the single lung group, eight patients had pulmonary hypertension and nine had parenchymal lung disease. Four of the 17 patients underwent repair of a cardiac defect with single lung transplantation. One-year actuarial survival was 68%. Pulmonary function has been excellent. The forced expiratory volume in 1 second was 79.6 +/- 13.6 (percent predicted), forced expiratory flow 25%-75% was 72.6 +/- 14.5 (percent predicted), and arterial oxygen tension was 82.8 +/- 10.06 mm Hg when measured at annual follow-up in a group of eight patients without obliterative bronchiolitis. Pulmonary artery pressures of systemic level or greater in the group with pulmonary vascular disease were normal at annual catheterization. Most patients had at least one episode of allograft rejection. Actuarial freedom from rejection at the end of 3 months was 30%. Three of the 17 single lung patients receiving lung lobes were children. Two children received living-related lobe transplants and one neonate received a lobe from a 2-year-old cadaver donor. Single lung transplantation is an effective therapeutic option for selected patients with vascular or parenchymal lung disease. Expanding indications will permit more individuals to receive transplants from the existing donor pool. Living-related and cadaver lobe transplantation will also increase the options available to children in need of lung transplantation.

Adolescent↗
PubMed1992

Cystic fibrosis. Target population for lung transplantation in North America in the 1990s.

Cystic fibrosis is the most common lethal genetic disease occurring in the white population. It is estimated that 3.5% of the 20,000 individuals with cystic fibrosis in North America will die each year of end-stage lung disease. Lung transplantation (heart-lung or double lung) is becoming more frequent as more patients are referred for this procedure. Since January 1988, we have evaluated 60 patients with cystic fibrosis for lung transplantation and have accepted 30 (50%). Nine patients (30%) died while awaiting a donor. Fifteen patients underwent transplantation (13 heart-lung and two double lung procedures). Actuarial survival at 1, 2, and 3 years is 76%. All survivors are without physical limitations. Pulmonary function, as determined by forced vital capacity, forced expiratory volume in 1 second, and arterial blood gas determinations, is within the normal range. Comparing these data with those of a group of patients without cystic fibrosis who underwent transplantation during the same period did not reveal any significant differences with respect to infection, rejection, and outcome. Preliminary data suggest that obliterative bronchiolitis is less prevalent at 1 year in patients with cystic fibrosis (19%) than in those without cystic fibrosis (41%). Patients with cystic fibrosis present a number of challenges. The problems of pleural adhesions from repeated infections, pleurodesis, and previous thoracic procedures are now readily approached through the bilateral thoracosternotomy (clam shell) incision. Insulin-dependent diabetes mellitus and low-dose corticosteroid therapy are no longer considered absolute contraindications. Both septic lungs must be removed at operation, either with heart-lung transplantation or with double lung transplantation. These data support the therapeutic efficacy of lung transplantation for patients with cystic fibrosis.

Actuarial Analysis↗
PubMed1991

Heart-lung transplantation in infants, children, and adolescents.

We have performed heart-lung transplantation in 10 children for the preoperative diagnoses of primary pulmonary hypertension (4), complex congenital heart disease with pulmonary hypertension (4), pulmonary atresia (1), and cystic fibrosis (1). Ages ranged from 4 months to 18 years. There were 15 episodes of pulmonary rejection, with an occurrence rate of 1.67 episodes per patient. Pulmonary infections occurred frequently, with an occurrence rate of 3.3 episodes per patient. The actuarial survival rate at 1 and 2 years was 78% and 47%, respectively. Patient attrition between 1 and 2 years was attributable to the complications of obliterative bronchiolitis, which has effected 71% (5/7) of the long-term survivors. Four of the 5 surviving children have minimal physical limitation and are in functional class I. These data support continued investigation into heart-lung transplantation in children and set the stage for further program development into single-lung transplantation in children.

Adolescent↗
PubMed1991

Effects of pulmonary restriction on hypercapnic responses of heart-lung transplant recipients.

Previous studies of hypercapnic ventilatory responses (HCVR) in human heart-lung transplant recipients (HLTX) have yielded conflicting results. We compared the HCVR of restricted transplant recipients (HLTX-R) to recipients with normal pulmonary function (HLTX-N), and normal controls (C). HLTX-R exhibited limited tidal volume responses, whereas their frequency responses were essentially identical to those of other subjects. Accordingly, HCVR of HLTX-R (1.45 +/- 0.59 l.min-1.Torr CO2(-1)) were significantly depressed compared with both HLTX-N and C (2.90 +/- 0.55 vs 3.05 +/- 1.23, respectively) (P less than 0.02). Despite undoubtedly greater ventilatory impedances, airway (mouth) occlusion pressure responses (Pm0.1) during hypercarbia of HLTX-R (0.46 +/- 0.28 cmH2O) were similar to those of C (0.43 +/- 0.20) and paradoxically blunted compared with HLTX-N (0.83 +/- 0.36) (P less than 0.02). We conclude that pulmonary reflexes are superfluous for maintenance of HCVR in HLTX with normal respiratory mechanics, whereas the presence of moderate restriction results in profound depression of CO2 responses among these subjects.

Adult↗
PubMed1991

Inspiratory timing of heart-lung transplant recipients during progressive hypercapnia.

The relationship between tidal volume (VT) and inspiratory duration (TI) displays biphasic characteristics during progressive hypercapnia in humans: an initial phase in which VT increases while TI remains constant (region I) and a subsequent phase with reciprocal decreases of TI as VT continues to increase (region II). Region II behavior is generally attributed, albeit inferentially, to lung volume-mediated inflation inhibition (Breuer-Hering reflex). To investigate this phenomenon, we compared CO2 responses of 10 heart-lung transplant recipients (HL) with normal pulmonary function tests and 13 normal controls. Despite pulmonary denervation, the HL exhibited region II behavior identical to controls. In four additional HL with pulmonary restriction, there were comparative decreases of the region II slope (P less than 0.05), but the absolute VT where the phase change between regions occurred was indistinguishable from the other groups. We conclude that TI shortening in humans during progressive hypercapnia occurs in the absence of pulmonary reflexes. The consistency of the VT associated with phase changes, despite pulmonary denervation, suggests that the stimulus for this behavior is volume displacement of extra-pulmonary respiratory structures.

Adult↗
PubMed1991

Hypercarbic ventilatory responses of human heart-lung transplant recipients.

To evaluate the effects of chronic pulmonary denervation on ventilatory control, we compared the hypercarbic ventilatory responses (HCVR) of 12 human heart-lung transplant recipients (HL) and 24 normal control subjects (C). The six male HL were subsequently compared with eight male heart transplant recipients (H), as well as the 12 male C. All subjects had normal spirometry, but lung volumes of both transplant groups were somewhat less than those of C. The HCVR of HL and C were indistinguishable (2.68 +/- 0.28 versus 2.71 +/- 0.22 L/min/mm Hg, respectively). The increment of mouth occlusion pressure (delta Pm0.1/delta CO2), however, was markedly greater in HL (P much less than 0.01). The three male groups also had equivalent HCVR, and again, the HL had an increased delta Pm0.1/delta CO2. HL men exhibited larger increments of VT and decreased frequency responses during CO2 rebreathing than did male C and H, although these differences were statistically significant only in the comparison between the transplant groups. We conclude that HL with normal spirometry have appropriate HCVR, despite pulmonary denervation. Pm0.1 responses of these subjects are increased, however, reflecting either a compensatory response to greater respiratory impedances or an occult alteration of ventilatory mechanics. Moreover, compared with subjects with similar pulmonary function, e.g., heart transplant recipients, the breathing pattern of HL during progressive hypercarbia is consistent with the absence of vagal-mediated inflation inhibition.

Adult↗
PubMed1991

Ulcerative tracheobronchitis after lung transplantation. A new form of invasive aspergillosis.

Invasive aspergillosis is frequently a fatal disease in the setting of immunosuppression, including organ transplant recipients. The fungus usually affects lung parenchyma and may disseminate from there. We have recently noted tracheobronchitis in six patients with heart-lung and lung transplants, three of whom had deep mucosal ulceration and histologic evidence of invasive aspergillosis. This apparently new form of invasive disease is initially limited to the anastomosis site and large airways. Ulceration, necrosis, cartilage invasion, and formation of a pseudomembrane are the pathologic features. In two patients subsequent disseminated aspergillosis occurred with a fatal outcome. In the two single-lung recipients, disease was limited to the transplanted side emphasizing the importance of abnormal local defense mechanisms in the airways of lung transplant recipients. Routine bronchoscopic examination of the airways is important in early detection of this complication. Oral therapy with the new, antifungal agent itraconazole was successful in five of the six patients, with fatal relapse in one. A classification of the various forms of saprophytic, allergic, and invasive forms of aspergillus tracheobronchitis, to include this new entity, is proposed.

Adult↗
PubMed1991

The "natural history" of the transplanted lung: rates of pulmonary functional change in long-term survivors of heart-lung transplantation.

Long-term pulmonary function in HLT is well preserved with no evidence of functional decline as a result of transplant "aging," providing the allografts remain free of complications. Long-term survivors with OB appear to be able to maintain adequate oxygenation despite the marked alterations of pulmonary function. The ability to preserve gas exchange at reasonable levels of oxygenation may be the factors permitting extended survival with OB for mean periods of 36.0 months or greater. Preliminary studies suggest that a declining FEF50/FVC, at a time when pulmonary function is normal, may be an index of impending airway disease. Physiologically, from a long-term point of view, HLT remains a viable option for selected patients with end-stage cardiopulmonary disease.

Bronchiolitis Obliterans↗