Search PubMed⌕ Search

Biomedical subjects

G A Patterson

Publications and source records attributed to G A Patterson.

At least 217 records · Page 12Linked to original sources
PubMed1991

Plasma atrial natriuretic factor concentrations in a canine model of right heart pressure overload.

Two studies were carried out in order to evaluate the plasma atrial natriuretic factor (ANF) concentrations, as well as hemodynamic and renal profiles in a chronic canine model of right heart pressure overload induced by pulmonary artery (PA) banding. In study I (n = 6), the animals were submitted to a gradual increase in pressure to clarify whether an increase in pressure or atrial distension was the main stimulus to ANF secretion. In study II (n = 6), right heart pressure overload was produced more rapidly, resulting in fluid retention and weight gain, thereby completing the model of right heart failure, and allowing an evaluation of the mechanisms involved in ANF resistance. In study I there were significant increases in right atrial pressure over baseline at 20 weeks, ANF levels at 24 weeks and right atrial area at 28 weeks following PA banding. In study II right heart pressures and ANF levels were higher than baseline at 12 weeks (p less than 0.0001), and fluid retention developed between 12-24 weeks in all dogs. The results suggest that increased right heart pressure, rather than atrial size, is a primary stimulus to ANF secretion in chronic right heart pressure overload. Despite the increases in right atrial pressure, clinical fluid retention occurred only with elevations of renin and aldosterone.

Aldosterone↗
PubMed1991

Is there ever a role for salvage operations in limited small-cell lung cancer?

Combined modality treatment with chemotherapy and radiation produces tumor regression in most patients with small-cell lung cancer, but the impact on survival has been small, and less than 20% of patients with limited disease survive 2 years. Survival time is extremely short after failure to respond or relapse after treatment. Local control remains a problem, with one third of patients having recurrence only at the primary site. In an attempt to prolong survival and perhaps achieve cure, we undertook surgical resection in 28 patients with limited small-cell lung cancer who did not have complete remission with standard treatment or who had only local recurrence after treatment. There were 28 patients, 22 male and six female, median age 61 years (range 41 to 76). All patients had been treated with chemotherapy and 13 had received preoperative radiotherapy to the primary site and mediastinum. Eight patients underwent an operation for relapse after complete remission. Five patients had had no response to treatment, three had had a slight response followed by progression during chemotherapy, and 12 had achieved partial response but had greater than 3 cm residual masses. Twelve patients required pneumonectomy, 15 lobectomy, one patient had unresectable disease, and two had bulky residual masses after the operation. Three others had microscopic residual disease. Pathologic examination showed only small-cell lung cancer in 18 patients, mixed small-cell and non-small-cell in four, and only non-small-cell lung cancer in six. There were only four patients with stage I disease, 10 with stage II, and 14 with stage III. The median survival from the date of diagnosis for the entire group is 105 weeks and from the date of operation, 74 weeks. The projected 5-year survival rate is 23%. The two patients with residual masses died with local progression, and distant metastatic disease developed in 17 others. One patient died at 6 years without recurrent disease. Eight patients are alive 2 to 5 years after diagnosis. Seven of these patients required only a lobectomy, four had stage I disease, two had stage II, and two had stage III disease. Five had pure small-cell lung cancer and three had mixed small-cell and non-small-cell tumors. All of the patients with pathologic stage I disease remain alive compared with one of 10 with stage II disease and two of 14 with stage III. In summary, relapse or failure to respond to chemotherapy may be due to non-small-cell lung cancer or a mixed tumor.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

A reevaluation of heparin requirements for cardiopulmonary bypass.

We wished to determine if reduction in the standard heparin administration for cardiopulmonary bypass could be accomplished safely with the use of membrane oxygenators. An experimental study was designed to evaluate two different heparin administration protocols for cardiopulmonary bypass with hollow-fiber membrane oxygenators. Two groups of six pigs were submitted to hypothermic cardiopulmonary bypass (28 degrees C) for 3 hours, then rewarmed, decannulated, and reassessed after 1 hour. In group I (control) heparin was administered to maintain the activated clotting time in excess of 450 seconds; in group II activated clotting time was maintained between 250 and 300 seconds. The mean total heparin administered was 41,000 units in group I and 25,000 units in group II. Concentration of coagulation factors II, V, and VIII, fibrinogen, and platelet count were determined before, during, and 1 hour after bypass. No significant difference in any of these coagulation parameters was observed between the groups. The performance of the oxygenators was similar in both groups, with no evidence of thrombosis. Thus reduced heparin administration, enough to keep activated clotting time between 250 and 300 seconds, was not related either to major coagulation factors and platelet consumption or to derangements in the oxygenator's performance.

Animals↗
PubMed1991

Single-lung transplantation for pulmonary vascular disease.

Six patients with end-stage pulmonary vascular disease received right SLTs. Though patients generally had difficult early postoperative courses, four of the six have survived from 3 to 23 months and have achieved good recovery of right ventricular function and good functional results. SLT is a viable option in selected patients with severe pulmonary hypertension even when right ventricular function is severely impaired.

Female↗
PubMed1991

Comparison of outcomes of double and single lung transplantation for obstructive lung disease. The Toronto Lung Transplant Group.

Single lung transplantation has recently been applied with success in patients with obstructive lung disease. Such patients were previously managed by bilateral pulmonary transplantation. Between November 1986 and January 1990, 18 patients underwent transplantation for obstructive lung disease in our center. Eleven double lung transplants and seven single lung transplants were performed in patients having a mean age of 43.4 and 44.1 years, respectively. Operative death occurred in two of 11 double lung transplantations and one of seven single lung transplantations. Each patient underwent preoperative and 3-month postoperative pulmonary function tests, arterial blood gas analyses, nuclear lung scans, and 6-minute walk tests. There was no difference in the preoperative values for any of these parameters. Double lung recipients had significantly higher forced expiratory volume in 1 second and forced vital capacity than single lung recipients. However, the ratios of forced expiratory volume in 1 second to vital capacity were not different. Arterial oxygen and carbon dioxide tension were not different between the two procedures. Whereas double lung transplantations caused a slight preponderance of perfusion to the right lung, the transplanted lung in single lung recipients received a mean of 79.5% +/- 12.3% of predicted flow and only 61.6% +/- 5.0% of predicted ventilation. Three-month 6-minute walk distances were markedly improved in both groups, with double lung recipients achieving 573.0 +/- 44.7 m in comparison with the 528.0 +/- 43.0 m achieved by the single lung recipients. Single lung transplantation is a satisfactory option in patients with obstructive lung disease and might offer significant advantages to the older patient population, in which risk of double lung transplantation is high.

Adult↗
PubMed1991

Right and left ventricular performance after single and double lung transplantation. The Toronto Lung Transplant Group.

Twelve single lung and nine double lung transplant recipients were studied before transplantation and at 3 months and 1 year after transplantation with serial right and left ventricular radionuclide angiograms. The resting right ventricular ejection fraction increased in the double lung recipients from 31% +/- 5% before transplantation to 43% +/- 11% at 3 months after transplantation (p less than 0.05) and then remained stable to 1 year. The single lung recipients also demonstrated a significant rise in ejection fraction from 25% +/- 11% before transplantation to 36% +/- 12% at 3 months after transplantation. Again, this remained stable to 1 year. The exercise right ventricular ejection fraction also showed a significant posttransplantation rise in the double lung recipients (p less than 0.005) that remained stable to 1 year. In the single lung recipients a trend was seen for a rise in the exercise right ventricular ejection fraction that did not reach statistical significance by 1 year after transplantation. Neither group had a significant change in rest or exercise left ventricular ejection fraction. The systemic blood pressure increased significantly by 1 year after transplantation in both groups. The heart rate increase with exercise at 3 months after transplantation was significantly greater in the single lung group (42 +/- 13 beats/min) than in the double lung group (14 +/- 13 beats/min) (p less than 0.005). These data indicate that a significant improvement in right ventricular function occurs after single and double lung transplantation.

Adult↗
PubMed1990

Results of single-lung transplantation for bilateral pulmonary fibrosis. The Toronto Lung Transplant Group.

Between November 1983 and August 1989, we performed single-lung transplantation for end-stage pulmonary fibrosis in 20 patients. Nine patients (45 percent) who survived for more than one year form the basis of this report. Before surgery, the nine survivors had severe restrictive lung disease, with a mean (+/- SD) vital capacity (VC) of 43 +/- 9 percent, a forced expiratory volume in one second (FEV1) of 50 +/- 9 percent, and a single-breath diffusing capacity (DLCO) of 36 +/- 9 percent of predicted values. One year after transplantation, the patients' VC had reached 69 +/- 10 percent, FEV1 79 +/- 15 percent, and DLCO 62 +/- 16 percent of predicted values. Relative perfusion to the transplanted lung rose from 63 +/- 14 percent (three days after surgery) to 77 +/- 7 percent within three months and stayed constant or increased slightly thereafter. Before surgery, despite supplemental oxygen at flow rates varying from 1 to 9 liters per minute, none of the patients could exercise beyond stage 1/2 (2.7 km [1.7 miles] per hour, 5 percent grade) on a modified Bruce treadmill-exercise protocol. All eight patients tested one year or more after transplantation achieved at least stage 1 (2.7 km [1.7 miles] per hour, 10 percent grade), and usually a higher stage, without supplemental oxygen. Arterial oxygen tension returned to normal values in most patients (87 +/- 13 mm Hg), and supplemental oxygen, which all patients required before surgery, was no longer needed by any patient after transplantation. We conclude that in carefully selected patients with end-stage pulmonary fibrosis, single-lung transplantation is an effective treatment.

Adolescent↗
PubMed1990

Complete foregut duplication.

Alimentary tract duplications are rare congenital anomalies with the majority identified in the pediatric age group. However, duplications may be seen in the adult population and require operative excision. A 53-year-old man was seen with vague, nonspecific symptoms and was found to have a complete esophageal and gastric duplication with communication to the normal alimentary tract. Appropriate-for-structure epithelium was noted throughout the length of the duplication.

Barium Sulfate↗
PubMed1990

Radiologic correlation with early physiologic function of the transplanted canine lung.

There is no single reliable method for assessment of the transplanted lung. Multiple modes of assessment are therefore used. In a canine model designed to assess lung preservation, the reliability of information gained from chest radiographs performed in the early post-transplant period was examined. The function of 20 left lung allografts, stored for 12 hours after pulmonary artery flush preservation was studied. Radiographs graded according to disease severity were compared with physiologic function of the transplanted lung assessed immediately and at three days post-transplantation. This protocol enables study of acute preservation-related lung injury and the delayed manifestations of ischemic and reperfusion injury after a three day period of recovery, while avoiding confounding rejection and infectious episodes. The chest radiograph did not reliably reflect function of the flush-preserved transplanted lung. Thus, relying only on this modality may lead to erroneous conclusions. In this study, the progression of radiographic changes associated with the "reimplantation response" differed from previous descriptions, possibly reflecting differences in operative technique or improved lung preservation.

Animals↗
PubMed1990

The superiority of an extracellular fluid solution over Euro-Collins' solution for pulmonary preservation.

Limited donor supply is the major factor restricting the application of lung transplantation. A uniformly reliable method of lung preservation would improve donor organ availability. At present, Euro-Collins' solution, an intracellular fluid-type solution, is most widely used in organ preservation. However, we have previously shown that initial pulmonary flush with an extracellular-type solution (low-potassium dextran solution [LPD]) provided better pulmonary preservation than Euro-C. In the present study, we used an in vitro-ventilated, blood-perfused rabbit lung model to examine whether the mechanism for this improvement was related to the effect of LPD during pulmonary flush or its effect during storage. Rabbit lungs were harvested and stored after pulmonary flush with different solutions (group 1: 400 ml of LPD; group 2: 400 ml of Euro-C; group 4: 300 ml of Euro-C followed by 100 ml of LPD; n = 5 in each group). The lungs were then preserved at 10 degrees C for 18 hr and reperfused with fresh venous blood. After 10 min of reperfusion, lungs in group 1 showed the highest PO2 (group 1: 124.4 +/- 7.7 mmHg; group 2: 46.2 +/- 9.4 mmHg P less than 0.01). Lungs in both group 3 and group 4 showed better lung function and lower wet/dry weight ratio than those in group 2. We conclude that LPD provides better lung preservation by its effects both on pulmonary flush and on storage.

Animals↗
PubMed1990

Cardiopulmonary exercise testing after single and double lung transplantation.

The cardiopulmonary response to exercise was investigated in six single and six double lung transplant recipients using a three-minute incremental work rate protocol on a cycle ergometer. Maximum VO2 averaged 44.2 +/- 9.2 percent and 48.5 +/- 5.0 percent of predicted maximal VO2 in the single and double lung transplant groups, respectively. No evidence of ventilatory limitation to exercise was found in either group. Circulatory factors that may have limited exercise capacity included anemia and submaximal heart rates. There was a strong correlation between VO2/kg at venous blood lactate level of 2.2 mEq/L and vital capacity/body surface area in the single, but not in the double, lung recipients. Maximum VO2 in these lung transplant recipients was comparable to previously published values in heart-lung transplant recipients. The factors that limit maximum exercise capacity after lung transplantation deserve further study.

Adult↗
PubMed1990

Donor selection for single and double lung transplantation. Chest size matching and other factors influencing posttransplantation vital capacity.

In six single lung transplant (SLT) and six double lung transplant (DLT) recipients, the relationships of the recipient's posttransplantation vital capacity (posttx VCR) to the recipient's predicted normal vital capacity (pred VCR) and the donor's predicted normal vital capacity (pred VCD) were investigated. After left SLT the left posttx VCR was correlated with the left predicted VCD (r = 0.83; p less than 0.05); however, no correlation was found between these after DLT. In contrast, there was a tendency toward correlation between the posttx VCR and the predicted VCR after DLT (r = 0.75; p less than 0.1), but no such trend was apparent after SLT. These results suggest that posttx VCR depends primarily on predicted VCD after SLT and on pred VCR after DLT. Therefore, in donor-recipient size matching for lung transplantation a donor with a pred VCD greater than the pred VCR should be chosen for a left SLT recipient, whereas a donor with a pred VCD near the pred VCR would be suitable for a DLT recipient.

Adult↗
PubMed1990

Double lung transplantation.

In the past 3 years we and other centers have accumulated a small experience with double lung transplantation. We continue to believe that it offers potential benefit to patients with bilateral septic lung disease and possibly to those with obstructive lung disease as well. We have encountered significant airway complications that several other centers have avoided by improved preservation and the technical modification of bilateral bronchial anastomosis. Reliable resolution of the problem of airway viability will permit more widespread application of double lung transplantation in selected patients with end-stage pulmonary disease.

Humans↗
PubMed1990

Lung transplantation for chronic obstructive pulmonary disease.

Lung transplantation has been successfully employed for a variety of obstructive lung diseases. Following successful application of combined heart-lung transplantation, double lung transplant appeared to offer potential advantages but was hampered by the frequent development of donor airway complications. During the past 2 years single lung transplantation has been successfully employed with increasing frequency in the management of nonseptic obstructive lung disease. Although early results are encouraging, long-term follow-up is necessary to determine the ultimate indications for single lung, double lung, and combined heart-lung transplantation in patients with chronic obstructive lung disease.

Graft Rejection↗
PubMed1990

Airway complications after double lung transplantation. Toronto Lung Transplant Group.

We have had success with en bloc double lung transplantation in the management of selected patients with end-stage parenchymal pulmonary disease. Airway complications have been more prevalent in our own experience with double lung transplantation than in reports of combined heart-lung transplantation from other centers. Between November 1986 and March 1989, 16 patients underwent double lung transplantation. Allografts were preserved by topical hypothermic immersion in 12 patients and by pulmonary artery flush with cold crystalloid solution in the most recent four patients. Thirteen patients underwent tracheal anastomosis and the most recent three patients underwent bilateral bronchial anastomoses. Fatal ischemic necrosis of the donor trachea and both main bronchi developed in three patients. Preterminal airway ischemia developed in a patient who had systemic sepsis. Partial anastomotic dehiscence, which went on to form fibrous strictures necessitating endoscopic placement of silicone rubber airway stents, developed in two additional patients. Two other patients had late strictures and required subsequent placement of bifurcation stents. There was no relationship between development of airway complications and gas exchange in the donor lungs, lung ischemic time, early postoperative gas exchange, early postoperative mean pulmonary artery pressure, or frequency of early postoperative rejection. Severe postoperative hypotension occurred in five of eight patients with airway complications and in three of eight patients without airway complications.

Humans↗
PubMed1990

Cardiac innervation after double lung transplantation. Toronto Lung Transplant Group.

Double lung transplantation has been successfully introduced for patients with end-stage pulmonary disease and preserved cardiac function. An advantage of this operation compared with heart-lung transplantation is retention of the recipient's heart. The operative dissection, however, may lead to interruption of sympathetic and parasympathetic pathways to the heart and consequent denervation of the native heart. The cardiac innervation of seven double lung transplant recipients was investigated by the heart rate response to carotid sinus massage, the Valsalva maneuver, intravenous injection of atropine, and exercise. Five single lung and two heart-lung transplant recipients were studied for comparison. Of the seven double lung transplant recipients, three had abnormal responses to carotid sinus massage, six to the strain phase of the Valsalva maneuver, and five to the release phase of the Valsalva maneuver. Three of six double lung transplant recipients tested had no response to intravenous injection of atropine, and five of seven patients had an abnormal recovery of heart rate after maximal exercise. No patient had a normal response to all interventions, and three patients had responses compatible with complete cardiac denervation. It is concluded that cardiac denervation may occur after double lung transplantation, most likely caused by surgical interruption of sympathetic and parasympathetic pathways during dissection of the recipient's trachea.

Adult↗
PubMed1990

Single lung transplantation and closure of patent ductus arteriosus for Eisenmenger's syndrome. Toronto Lung Transplant Group.

A case report of the first single lung transplantation and closure of a patent ductus arteriosus for Eisenmenger's syndrome is presented. The operation was performed on Sept. 28, 1988. The patient was extubated on postoperative day 8, discharged from the intensive care unit on postoperative day 13, and discharged from the hospital on postoperative day 43, free of symptoms and without supplementary oxygen. Subsequent symptoms of dyspnea, presyncope, and fatigue recurred in association with subvalvular right ventricular outflow tract obstruction. Symptomatic improvement occurred gradually in association with reduction of the outflow tract obstruction. The patient is in New York Heart Association class I-II 12 months after the operation. The rationale, methods, and management of this patient are discussed, as well as the potential for application of this operation in similar settings.

Adult↗