PubMed Health⌕ Search

Biomedical subjects

L Brownstein

Publications and source records attributed to L Brownstein.

7 recordsLinked to original sources
PubMed1999

Patient outcome as a selection criterion in determining treatment mode.

The climate of health care reform encourages scrutiny of traditional and new forms of medical and surgical therapy. With the emergence of technologically innovative cardiac procedures, therapy advocates must weigh cost versus patient outcomes. Therapies range from purely medical management, through staged interventions, to median sternotomy and cardiopulmonary bypass. Outcomes will necessarily be related to quality of life. A literature search was performed to determine types of medical and surgical therapies associated with patient outcomes as they define quality of life. Medical treatment may include the use of anti-platelet therapy, beta-blockers and diuretics to treat the cardiac patient at low risk who can maintain an acceptable quality of life. Improvements in medical therapies may extend the life of the low-risk patient, eliminating the need to consider bypass surgery. Some patients at high risk, or with left ventricular hypertrophy combined with an impaired ejection fraction, may require coronary artery bypass surgery. Studies indicate that patients undergoing open heart surgery demonstrate significant improvement in functional classification, increased activity and reduction in anti-anginal medications. Proponents of minimally invasive surgery claim potential benefits of lower surgical trauma, shorter hospital stays and shorter recovery times. Quality of life is defined by outcomes. Only by comparing outcomes of all available therapies can a physician or patient make an informed decision regarding treatment.

Cardiac Surgical Procedures↗
PubMed1998

A programme to prepare instructors for clinical teaching.

Clinical staff perfusionists are responsible for training perfusion students to perform tasks and manage patients in the clinical setting. They are often the least prepared to assume this teaching role. To address this need, a modular programme has been developed to provide the teaching staff with instructional skills. Adult learning theory specifies that an effective learning environment addresses issues of saliency, motivation, retention and transfer. Adults have different expectations, so this programme is designed to maximize this process. The programme is comprehensive and may be used for didactic instruction as well. Derived from a model designed for physicians as teachers, five modules provide theoretical support for teaching techniques, learning tools and management techniques for giving feedback and evaluating performance. Specifically, the topics address the following subjects: managing and motivating learners; teaching medical problem solving; teaching clinical skills; giving feedback and evaluating performance. The short curriculum is based on teaching principles that apply to adult learners with diverse learning styles. While presenting techniques to use with different types of learners, the programme itself incorporates these techniques in teaching the teachers. The modules use lectures, demonstrations, role playing and video taping to challenge teachers and learners in the cognitive, psychomotor and affective domains. The success of this programme is its ability to engage each participant in the learning process.

Adult↗
PubMed1994

Determination and comparison of heat exchange efficiency of four commercially available blood cardioplegia sets.

An in vitro comparison of the heat exchange properties of the Electromedics D1081A, Sarns MP-4 'Conducer Coil' 165720, Bentley HE-100 and the Shiley BCD Plus 4: 1 blood cardioplegia sets was performed. The efficiency was calculated for each heat exchanger and post-heat exchange blood path temperatures were compared. The calculated efficiency for each heat exchanger is as follows: Electromedics D1081A at 18 l/minute coil water flow (0.95); Sarns MP-4 165720 at 9 l/minute coil water flow (0.93); Bentley HE-100 at 10 l/minute coil water flow (0.91); Shiley BCD Plus at 15 l/minute coil water flow (0.90). Blood path, precoil temperatures for each unit were compared statistically with no differences found (p > 0.05). Blood side, postcoil temperatures were then compared. The average postcoil blood path temperature of the Electromedics D1081A was 1.6 degrees +/- 0.1 degree C, of the Sarns MP-4 165720 it was 2.1 degrees +/- 0.1 degree C, of the Bentley HE-100 it was 2.7 degrees +/- 0.3 degree C, and the Shiley BCD Plus 3.0 degrees +/- 0.4 degree C. The results of this experiment indicate that the average postcoil temperature of the Electromedics D1081A was lower than the Sarns MP-4 165720 (p < 0.05) which was lower than that of the Bentley HE-100 (p < 0.05) and Shiley BCD Plus (p < 0.05). No statistical difference was found between the average postcoil temperature of the Bentley HE-100 and the Shiley BDC Plus.

Blood Physiological Phenomena↗
PubMed1988

Development of the Philadelphia Heart System.

A new pneumatic artificial heart system has been developed. The design criteria have been to produce an integrated series of blood pumps and drive systems that would reduce blood trauma and reactivity, while incorporating industrial, mass-production techniques. The system attempts to reproduce the natural heart's pressure and flow waveforms and allows the prosthetic valves to be installed in a manner consistent with their design. The system's ventricles are constructed entirely of polyurethane by a combination of vacuum-forming and solution-casting techniques. The atrial cuffs and arterial grafts are permanently attached to the pumps and do not incorporate a quick connect system. The prosthetic valves are sewn into the inflow and outflow tracts using their clinical sewing rings. Besides eliminating the crevices normally found in quick connect systems, this method mounts the valves in an extremely compliant housing to increase shock absorption. The drive system produces a systolic air flow with a variable pressure rise (dP/dt) to reduce mitral valve closing velocity. This system has been implanted into 25 calves to date, of which 17 were chronic experiments. In 14 animals, St. Jude bileaflet valves were used and these animals had a mean survival of 39 days. Six of these animals survived over 30 days, with the longest being 129 days. All of the animals showed the characteristic postoperative drop in red blood cell count and hematocrit that returned to near preoperative values in about 3 weeks. The plasma free hemoglobin values generally remained below 5 mg/dl. The necropsies performed on several of the earlier animals revealed renal infarcts. However, in two of the later experiments, no kidney damage was found. The blood contacting surfaces of the atrial cuffs from the animals surviving over 100 days were covered with a fibroproliferative pseudoneointimal growth that extended from the sewing rings to the natural atrial tissue. Grossly, this appears to be the same type of tissue response seen when only a valve is implanted in a natural calf heart.

Animals↗
PubMedDate not supplied

Results of the unidirectional Centri-Safe arterial valve for prevention of retrograde flow during cardiopulmonary bypass.

Retrograde blood from the aortic cannula into the cardiopulmonary circuit may lead to aortic air emboli when nonocclusive centrifugal pumps are used. The authors tested a nonregurgitant, unidirectional valve containing a Teflon ball occluder to prevent backflow. In vitro measurements of leakage rate, forward flow pressure drop, burst strength, and hemolysis levels along with animal (n = 12) and human (n = 12) in vivo hematologic and hemolysis levels were measured. Data were analyzed by paired and unpaired Student's t-test. Pressure drop differences at flows of 5 l/min were 7.3 +/- 0.3 mmHg before and 7.6 +/- 0.1 mmHg after 10,800 cycles of pulsatile pumping. (P = NS). Leakage rate during this period at pressures of 100 mmHg was not significant. Volume required to close the Teflon ball was less than 1 ml. Hemolysis analysis done in vitro and in vivo in control (no valve) and experimental (valve) groups used hemoglobin, hematocrit, platelets, plasma free hemoglobin, and lactic dehydrogenase as hemolysis indices. There were no statistical differences. The authors conclude that the CentriSafe valve (Cardiac Systems, Inc., Conshohocken, PA) is safe and prevents fatal backflow and air emboli. The valve is nonthrombotic in anticoagulated blood, can be opened and closed thousands of times, and has a burst strength equal to or greater than other components in the perfusion setup.

Animals↗