Biomedical subjects

R S Bonser

Publications and source records attributed to R S Bonser.

95 records · Page 6Linked to original sources

PubMedDate not supplied

Acute physiologic changes after extended pulmonary preservation.

The physiologic effects of 12-hour lung preservation were assessed in six mongrel dogs studied for 20 hours after double-lung allograft implantation. Donor animals were pretreated with allopurinol (30 mg/kg) and methylprednisolone (500 mg) intravenously at anesthesia induction. Heart-lung blocks were harvested after cardioplegic arrest, and a simple pulmonary artery flush of 4 degrees C modified Collins' solution was administered at 15 ml/kg/min. The lungs were ventilated with 100% nitrogen during flushing and inflation. Recipient animals received an infusion of deferoxamine (20 mg/kg) during implantation and were pretreated with methylprednisolone (500 mg) intravenously. All six implantations were technically successful. Two animals died of cardiac standstill 12 and 24 hours postoperatively. Gas exchange deteriorated after implantation compared with donor levels but remained in a range compatible with survival, and at 20 hours arterial oxygen tension (FiO2 0.4) was 138 +/- 91 mm Hg. Similar changes were seen in alveolar-arterial oxygen gradients and arterial-alveolar oxygen tension fraction. Elimination of carbon dioxide was satisfactory. Pulmonary venous shunt fraction rose significantly at the end of the study. Hemodynamic changes consisted of a gradual increase in pulmonary vascular resistance and a reduction in cardiac output. Lung mechanics also deteriorated, with a gradual rise in airway resistance and a fall in compliance. The double-lung model allows detailed assessment of the early effects of preservation and may have certain advantages over heart-lung models of preservation. The preservation technique warrants further study.

Allopurinol↗

PubMedDate not supplied

Technique of clinical double-lung transplantation.

Clinical double-lung transplantation has now been successfully performed at the University of Minnesota, Minneapolis. Donor care and operation are similar to heart-lung donor management. The most important parts of the recipient operation are to remove the lungs without injury to the phrenic, vagal, or recurrent nerves and to ensure hemostasis. In addition, the integrity of the tracheal anastomosis should be ensured by an omental wrap. The operative technique, developed and modified from our laboratory experience, is described.

Anastomosis, Surgical↗

PubMedDate not supplied

Optimal management of the heart-lung donor.

Optimising the management of the heart-lung donor may increase the number of organs suitable for transplantation. This can be achieved by understanding the pathophysiology of brain death and implementing therapeutic measures to counteract the deleterious effect of brain death on end-organ function.

Heart↗

PubMedDate not supplied

The management of bleeding following surgery requiring hypothermic circulatory arrest.

BACKGROUND: Hemostasis is a significant problem in aortic surgery requiring profoundly hypothermic techniques. Aprotinin, a serine protease inhibitor, reduces blood loss in high-risk coronary and valve surgery, but its use in profound hypothermia is controversial. METHODS: To evaluate the role of a modified protocol of aprotinin administration we have retrospectively reviewed our results in 73 procedures when hypothermic circulatory arrest was necessary. Thirty-seven (51%) were emergencies. Aprotinin was not administered until bypass had been recommenced after the period of circulatory arrest, and was then given as a bolus of 280 mg into the bypass machine followed by an intravenous infusion of 70 mg/hour. RESULTS: In this series the 30-day mortality was 12.3% (9/73), and the in-hospital mortality 13.7% (10/73). Mortality in the elective group was 11.1% and 16.2% in the emergency group. The mean blood loss over the first 12 hours after surgery was 542 mL; the mean transfusion requirement during surgery and this 12 hour period was 3.6 units of blood. Six patients (8.2%) developed transient renal dysfunction which did not require intervention. CONCLUSIONS: This data does not support the adverse effect of aprotinin upon early survival. Although early reports were of concern, the role of aprotinin as an adjunct to hemostasis requires further investigation.

Adult↗

PubMedDate not supplied

The natural history of thoracic aortic aneurysm disease: an overview.

Relatively little is known of the natural history of thoracic aortic aneurysms (TAA). The limited data available suggests that survival is at best equivalent to that observed for abdominal aortic aneurysm (AAA), and probably significantly worse. Patients with an AAA > 6 cm diameter have a 5-year survival of 10%, with a cumulative risk of rupture over 10 years of 43%. Rupture is also responsible for death in 25% of patients with 4-7 cm AAA. Natural history studies of TAA report a 1- and 5-year survival of 39%-52% and 13%-19%, respectively, but many studies include data on acute type A dissection. Although most mortality in patients with TAA is related to aneurysm rupture, data on the relationship between aneurysm size and rupture risk remains scarce. TAA is a highly lethal condition warranting consideration of elective, prophylactic surgical repair. However, the timing of surgery is often a difficult clinical decision, particularly in asymptomatic patients or those with comorbid conditions. Surgery for TAA carries a significant mortality and potentially permanently crippling morbidity. A recommendation of surgery represents a balance, weighing estimates of TAA natural history and rupture risk against operative mortality and complication rate, while carefully considering the impact of important comorbid conditions, e.g., ischemic heart disease, obstructive pulmonary disease, and renal dysfunction. When to intervene is a critical question facing cardiovascular surgeons and is based upon an assessment of the risk of rupture. This risk is related to the site, aetiology, size, and expansion rate of the aneurysm.

Aortic Dissection↗