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Biomedical subjects

J M Dunn

Publications and source records attributed to J M Dunn.

At least 73 records · Page 4Linked to original sources
PubMed1984

Mineralization of short term pericardial cardiac patch grafts.

Glutaraldehyde fixed patch grafts of bovine pericardium were implanted in myocardial windows in young (3-4 months old) sheep. The samples were retrieved after one to three weeks for study with scanning electron microscopy (SEM) and energy dispersive x-ray microanalysis (EDX). A layer of porous material (pseudoneointima, PNI), consisting mostly of a dense mesh of fibers interspersed with blood cells, was noted to form on the blood contacting surface of the graft. Four distinct sets of mineralization were noted in the retrieved grafts: (1) at the blood contacting surface of the PNI; (2) within the PNI at the junction between layers of PNI with differing densities; (3) near the junction of PNI and pericardium (but in the PNI); and (4) within the pericardium. In both the PNI and pericardium the mineral was shown by EDX analysis to contain both calcium and phosphorous indicating the mineral to be a calcium phosphate. Mineralization in the PNI differed from that in the pericardium; in the PNI it was deposited in discrete regions and apparently in association with thrombi while in the pericardium it was distributed diffusely within the collagen matrix, which may influence its formation.

Animals↗
PubMed1983

Pulmonary resection for complications of cystic fibrosis.

Pulmonary sequelae account for a large proportion of the morbidity and mortality of cystic fibrosis. Bronchiectasis, hemoptysis, and abscess formation are often not responsive to conservative medical therapy. Pulmonary resection in selected cystic fibrosis patients is safe and therapeutically rewarding. Eleven pulmonary resections in ten patients with cystic fibrosis were performed. Patients ranged from 2.5 to 19 years of age. Indications for resection were: (1) abscess and bronchiectasis (nine patients), (2) atelectasis and mass (one patient), and (3) life-threatening hemorrhage (one patient). Surgical resection was employed only for medically refractory lesions which were life-threatening or contaminated otherwise functional lungs. Resection was limited to the most severely diseased areas, sparing functional lung parenchyma when possible. In this series, 9 lobectomies, 1 pneumonectomy, and 1 segmentectomy were performed. Preoperative management included aggressive chest physiotherapy and postural drainage, rigid bronchoscopic lavage, and broad-spectrum parenteral antibiotics. All patients were extubated in the operating room immediately postoperatively. Tracheostomy was not employed. There were no perioperative complications. All patients experienced subjective improvement. Objectively, improvement following surgical resection included: decreased cough and sputum production, and decreased incidence of exacerbations of pulmonary infections. Limited pulmonary resection when combined with intensive preoperative pulmonary toilet is a safe adjunct in the treatment of bronchiectasis and hemoptysis secondary to cystic fibrosis. Pulmonary resection should be limited to only severely destroyed lung parenchyma which is refractory to medical management. In contradistinction to other authors we have not found tracheostomy a necessary adjunct in surgical management.

Adolescent↗
PubMed1982

Palliative repair of transposition of the great arteries with criss-cross heart: ventricular septal defect and hypoplastic right (systemic) ventricle.

Four cases of palliative Mustard or Senning repair for transposition of the great arteries (TGA) with ventricular septal defect (VSD), hypoplastic right ventricle, and superior-inferior ventricular configuration are presented. The palliative Mustard procedure-a Mustard repair without VSD closure-is usually reserved for patients with pulmonary vascular obstructive disease (PVOD). In such cases, VSD closure would result in left ventricular failure. Each of our four patients had normal or only slightly elevated pulmonary resistance (1.0 to 5.2 Wood units). However, in each case a hypoplastic right ventricle precluded VSD closure. All four patients had transposition-like hemodynamics with unfavorable streaming to the great arteries, despite the fact that two patients had a levo arterial configuration. In each case, the ventricular relationship included a hypoplastic, superior right ventricle with a horizontal ventricular septum-the so-called "upstairs-downstairs" or "superior-inferior" heart. All patients had previous balloon atrial septostomy or open septectomy to improve atrial mixing. Two patients had previous pulmonary artery banding because of increased pulmonary flow. All four patients remain survivors of the palliative Mustard or Senning repair, which was performed at 10 months, 5 1/2, 12, and 16 years. In each case, there was a marked improvement of symptomatology with a decrease of hemoglobin (mean 21.1 gm/dl preoperatively to 15.3 gm/dl postoperatively) and an increase of arterial oxygen saturation (mean 78 vol % preoperatively to 93 vol % postoperatively). This is the first palliative Mustard or Senning repairs in patients with TGA, VSD, and hypoplastic right ventricle without PVOD. The procedure produces gratifying palliation for these patients.

Adolescent↗
PubMed1981

Pseudomonas maltophilia bacteremia in children undergoing open heart surgery.

Pseudomonas maltophilia was isolated from intraoperative blood cultures in eight of 13 children undergoing open heart surgery during a five-week period. Antibiograms were identical and included resistance to prophylactic antibiotics. The source of the outbreak was traced to contamination of both the calibration device used on the pressure monitoring system and the sensor surface of transducers used in this system. In a mock system, calibration with a contaminated device resulted in recovery of the organism from transducer dome fluid. Dye studies confirmed the integrity of the transducer membrane but demonstrated reflux of dome fluid into the monitoring line fluid. A case-control study revealed no patient- or surgery-related factors predisposing to P maltophilia bacteremia and no excess of morbidity or mortality in patients as a result of bacteremia. The outbreak was confined to patients undergoing open heart surgery and was terminated abruptly by sterilization of transducers and revision of the calibration device.

Cardiac Surgical Procedures↗
PubMed1981

Porcine valve durability in children.

Calcification of porcine heterograft valves may be greater in the pediatric than in the adult population. This multicenter study evaluates the long-term actuarially determined durability of porcine valves in children less than 21 years old. We evaluated 227 late survivors of porcine valve implantation with 47 aortic valves, 67 mitral valves, 14 tricuspid valves, 14 pulmonary valves, 77 pulmonary conduits, and 8 apicoaortic conduits. In this series, 20 porcine valves degenerated, most in the aortic and mitral positions. At 5 years 40% of aortic, 40% of mitral, 100% of tricuspid, 100% of pulmonary, and 89% of pulmonary conduits remained functional. In this series, calcification and dysfunction occurred significantly faster (p less than 0.05) in younger compared with older children and in left-sided or systemic positions (aortic and mitral) compared with right-sided positions (tricuspid, pulmonary, and pulmonary conduit).

Actuarial Analysis↗
PubMed1979

Hyperbaric oxygen. A new adjunct in the management of radiation necrosis.

Radiation necrosis is a significant complication of surgery for previously irradiated head and neck malignant neoplasms. We used hyperbaric oxygen therapy (HBO) as adjunctive therapy in 52 cases of radiation necrosis. Thirty-nine cases involved the head and neck. Nineteen of 23 cases of osteoradionecrosis of the mandible remain arrested after as much as two years of follow-up. Fifteen of the 16 cases of soft-tissue radionecrosis of the head and neck were successfully managed with HBO therapy as an adjunct to surgery and antibiotics. Fibroblastic proliferation, collagen formation, and capillary budding require at least 20 to 30 mm Hg of wound Po2. This effect can be achieved in wounds that are rendered hypoxic by radiation endarteritis and ischemia with high-dose or hyperbaric oxygenation.

Adult↗
PubMed1979

Early and late results of surgical correction of pulmonary artery sling.

Since 1976, we have operated on 4 children with pulmonary vascular sling. They were 5, 12, 19, and 54 months old. All patients were seen initially with severe stridor. Diagnosis was made by barium swallow in all 4. Each child was operated on through a left thoracotomy; the left pulmonary artery was dissected deep between the trachea and esophagus. Systemic heparinization and microsurgical techniques were used. All patients improved after operation. Radioisotope pulmonary ventilation/perfusion scans were performed 9, 9, 14, and 21 months after operation. Decreased ventilation was noted in the right upper lobe of one scan; the other three ventilation scans were normal. Perfusion scans showed good patency of both pulmonary arteries in all 4 patients. It is concluded that pulmonary vascular slings should be treated surgically as soon as diagnosed. Delayed operation can lead to severe tracheomalacia, as demonstrated in our 54-month-old patient.

Child, Preschool↗
PubMed1979

Hyperbaric oxygen and chronic osteomyelitis.

Forty patients with chronic osteomyelitis were treated with hyperbaric oxygen as an adjunct to surgical therapy and antibiotics and followed for an average of 2 years with a recurrence rate of 15%. The mechanism of action of hyperbaric oxygen in osteomyelitis is probably an indirect one of improving local vascularity and potentiating phagocytosis. Many of these patients represent a refractory group with poor prognosis due to the etiology of the infection, site of involvement, and duration of infection prior to treatment. The recurrence rate following this mode of treatment seems to be primarily related to inadequate surgical management. There was no definite correlation between the site of the infection of pathologic organism and recurrence. Although this is a preliminary report, the results are encouraging. Hyperbaric oxygen may be indicated as an adjunct to good surgical and medical management, particularly in patients with refractory chronic osteomyelitis and in whom ablative surgery is under consideration as the only other means of controlling the infection.

Adolescent↗
PubMed1978

Reliability of selected psychomotor measures with mentally retarded adult males.

Reliability estimates were determined for 24 moderately mentally retarded adult males on three psychomotor tasks. For four consecutive days measures were taken on reaction time, auditory and visual, 15 trials daily for each; grip strength, dominant and non-dominant hand, two trials daily for each; and standing long jump, three trials daily. Analyses of variance, adjusted for day-to-day trend, were applied to the data. Intraclass reliability coefficients for both dominant (R = .96) and non-dominant (R = .94) hand-grip strength were high. The reaction time scores for both the auditory (R = .87) and visual (R = .83) data were moderately reliable. A low reliability coefficient (R = .49) was obtained for the standing long jump.

Adult↗