Search PubMed⌕ Search

Biomedical subjects

R L Fisk

Publications and source records attributed to R L Fisk.

32 records · Page 2Linked to original sources
PubMed1970

Isolation and controlled perfusion of the canine brain.

Experiments were carried out to evaluate the adequacy of internal carotid perfusion of the isolated canine brain and the application of a perfusion apparatus which was designed to facilitate environmental control for the isolated functioning organ. Anatomic considerations and the surgical isolation of the cerebral vasculature are presented in detail. Intact animals were used to provide physiologic arterial blood which was pumped under pressure control to six brains which were maintained at simulated low, normal and high intracranial pressures. Good electrocortical activity has been preserved for up to eight hours in the preparation.The methods provide a useful model for the future investigation of cerebral circulation, metabolism and function under normal and various pathophysiologic conditions.

Animals↗
PubMedDate not supplied

Case report: chronic disseminated intravascular coagulation due to occult carcinoma.

A patient with a relatively localized occult carcinoma of the lung and hemorrhage secondary to chronic disseminated intravascular coagulation (DIC) which continued for eight months is described. Despite continuing DIC two major operations were performed without excessive blood loss. Preoperative heparinization, in vitro clotting of the arterial graft, and temporary postoperative reversal of systemic heparin were utilized for abdominal aortic aneurysm resection. Blood product replacement therapy facilitated an emergency laparotomy. The patient was also managed successfully for several months without anticoagulant therapy. A hypothesis that vascular thrombi are not a necessary prerequisite for DIC is proposed. This hypothesis is based on the absence of thrombi or evidence of ischemia in this patient and in others and is supported by experimental observations made by other investigators.

Aged↗
PubMedDate not supplied

Total pericardial replacement. Design and preliminary evaluation in greyhounds.

Existing pericardial substitutes, used for the prevention of pericardial and pleural adhesions to the epicardium, are in the form of a patch. To improve on this concept, an elastic, anatomically correct, implantable sac has been developed for total pericardial replacement. Total pericardial substitutes fabricated from Silastic silicone rubber and Mitrathane polyetherurethane urea were implanted in greyhound dogs and harvested at 8 weeks. Pericardial adhesions were prevented by the substitutes that remained intact. Fibrous tissue formation had occurred on the epicardium underlying the substitutes, the extent being more severe in response to the Silastic compared with the Mitrathane. However, the Silastic was superior to the Mitrathane in retention of its tensile strength and elastic modulus over the implant period (p less than 0.05). Further development of total pericardial substitutes from different materials shows promise.

Animals↗
PubMedDate not supplied

In vivo results of hydrogel composite pericardial substitutes.

In this study, two improved pericardial patches were developed and evaluated for their efficacy as pericardial substitutes. The patches are composites consisting of a hydrogel (PHEMA) that coats an underlying mesh (either ETFE or PET). Studies were conducted using subcutaneous implants in rats and pericardial patch implants in greyhound dogs. Adhesions between the substitute and pericardium and the epicardium were minimal. The ETFE composite patch caused an unacceptable epicardial reaction. The PET patch results were encouraging; the epicardium was largely unaffected by the patch.

Animals↗
PubMedDate not supplied

A hydrogel pericardial patch.

Patients undergoing repeat cardiac operations are higher operative risks than those undergoing an initial cardiac procedure because adhesion formation can occur if the native pericardium is not closed. A unique composite patch that may be used to augment the pericardial tissue when primary closure is not possible has been developed. The patch is made of a hydrogel, poly (2-hydroxyethyl methacrylate), reinforced with an ethylene tetrafluoroethylene (ETFE) mesh. The mesh provides the needed mechanical properties, whereas the patch's surface properties are comparable to the hydrogel. Two types of patches were fabricated: one with the mesh weave at a perpendicular orientation and one at 45 degrees to the principle loading direction. The patches were mechanically tested and compared with canine pericardium. Ultimate tensile strength of the patches is not significantly different from canine pericardium (p less than 0.05), are the patch suture strength is nearly twice that of canine pericardium. The perpendicular patch is stiffer than canine pericardium, whereas the 45 degree patch is not (p less than 0.05). The 45 degree patch shows considerable promise as a pericardial substitute because it closely matches the properties native canine pericardium.

Animals↗