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Biomedical subjects

C W Hibbs

Publications and source records attributed to C W Hibbs.

26 records · Page 2Linked to original sources
PubMed1975

Dynamic alveolar mechanics as studied by videomicroscopy.

The in vivo morphology of rat alveoli has been recorded and studied on videotape. The dynamic internal structure has been compared to that observed by histologic section from lung rapidly frozen with liquid nitrogen. The irreversible nature of local alveolar wall movement has been demonstrated in animals ventilated both with and without positive end-expiratory pressure (10 cm water) by parametrically comparing the distances between two sets of paired points measured sequentially across internal alveolar surfaces at intervals of 0.017 sec. Geometric hysteresis was significantly less in the animals ventilated with positive end-expiratory pressure. This hysteresis can be explained by irreversibility in alveolar surface area apart from any irreversible dependence on surface tension. Sharp reverses and rapid changes in geometric hysteresis suggest that the length-tension properties of elastic tissue within the alveolar wall and interface forces from adjacent alveoli are important determinants of local alveolar wall motion and pulmonary hysteresis.

Animals↗
PubMed1975

An abdominal left ventricular assist device: preclinical studies.

An abdominally positioned left ventricular assist device (ALVAD) has been evaluated in our most recent series of 25 calves weighing 99 plus or minus 12 kg. The ALVAD is a pneumatically actuated bladder pump, positioned subdiaphragmatically and connected between the left ventricular apex and the infrarenal abdominal aorta. The mean survival time in the calves was 41 days and the longest 65 days. The major effects of the pump are reduction of all indices of left ventricular work and increases in systemic perfusion. In the awake, unanesthetized calf, left ventricular pressure, dP/dt, and stroke work were decreased while peak aortic pressure, stroke volume, and cardiac output increased. These effects were corroborated at cardiac catheterization two to four weeks postoperatively; left ventriculograms also showed increases in ejection fraction. These data demonstrate the ALVAD's effectiveness in assuming left ventricular function and support over extended periods. The device has been developed for short-term postoperative clinical use in patients with reversible left ventricular failure.

Abdomen↗
PubMed1975

Evaluation of cardiac function and venous return curves in awake, unanesthetized cialves with an implanted total artificial heart.

1) The implanted TAH offers a method of evaluating the effects of varying physiologic demands cardiac output and venous return. 2) Cardiac output and venous return measurements offer a method of evaluating system design of the device and driving and control-logic improvements in awake, unanesthetized animals. 3) The obtained cardiac function and venous return curves suggest that the present TAH is less responsive to increases in right atrial pressure than the natural heart, but is still completely controlled by venous return. Therefore, it is extremely important to make every effort to eliminate any factor causing excessive venous return.

Animals↗
PubMed1975

Peripheral effects of cardiovascular drugs during total artificial heart pumping in the awake unanesthetized calf.

Effects of various drugs, such as Isuprel, Neo-synephrine, aminophylline and quinidine, have been evaluated and compared in both control and TAH calves. In the control calves, the cardiac effects of these drugs were overlapped by vascular effects. But in the TAH calves, pure vascular effects have been clearly shown. 1) The peripheral effects of Dibenzyline and Inderal were evaluated in the TAH calves. 2) From these results, it has been concluded that the TAH animal is a useful model for the study of the peripheral vascular response to drugs in awake, unanesthetized subjects.

Aminophylline↗
PubMedDate not supplied

Infusion therapy devices: selection, cost and maintenance.

Each healthcare facility must formulate and justify their policies and procedures for providing infusion therapy. The materials manager and/or central supply manager should be involved in this process. Each facility must address and define its own specific applications and justify the decisions within the respective medical, nursing, technical and administrative staffs. Furthermore, the facility's policy and procedures should not be static. They must be reviewed and upgraded at regular intervals because of the changes in medical technology and pharmacology. Proper understanding of the definitions addressed in this article will assist in simplifying committee decisions and provide for a more comprehensive and rational policy.

Calibration↗
PubMedDate not supplied

Taking charge of high-tech equipment purchases.

Today's rising operating costs and declining revenues have focused attention on the importance of materiel managers in influencing their hospital's struggle to balance fiscal responsibility with the need to remain in step with advancing technology. This change in the status has left some materiel managers still struggling to find ways to fulfill the expectations of their hospital's administration and many members of the staff. One way materiel managers can respond is by taking the lead in establishing a strategic planning mechanism for capital equipment purchases; by insisting that equipment purchase decisions be made in the context of the whole hospital; by insisting that purchase decisions look beyond price to return on investment; and by insisting that each acquisition be a worthwhile, long-term investment for the hospital. The obvious justification for these demands is that they make economic sense.

Capital Expenditures↗