Application of Micropore Filter Technology: Exploring the Blood Flow Path in Arterial-Line Filters and Its Effect on Bubble Trapping Functions.
Conventional arterial-line filters commonly use a large volume circular shaped housing, a wetted micropore screen, and a purge port to trap, separate, and remove gas bubbles from extracorporeal blood flow. Focusing on the bubble trapping function, this work attempts to explore how the filter housing shape and its resulting blood flow path affect the clinical application of arterial-line filters in terms of gross air handling. A video camera was used in a wet-lab setting to record observations made during gross air-bolus injections in three different radially designed filters using a 30-70% glycerol-saline mixture flowing at 4.5 L/min. Two of the filters both had inlet ports attached near the filter-housing top with bottom oriented outlet ports at the bottom, whereas the third filter had its inlet and outlet ports both located at the bottom of the filter housing. The two filters with top-in bottom-out fluid paths were shown to direct the incoming flow downward as it passed through the filter, placing the forces of buoyancy and viscous drag in opposition to each other. This contrasted with the third filter's bottom-in bottom-out fluid path, which was shown to direct the incoming flow upward so that the forces of buoyancy and viscous drag work together. The direction of the blood flow path through a filter may be important to the application of arterial-line filter technology as it helps determine how the forces of buoyancy and flow are aligned with one another.
In-vitro quantification of gaseous microemboli in two extracorporeal life support circuits.
During the course of extracorporeal membrane oxygenation, patients are at constant risk of exposure to air emboli. Air emboli may enter the circuit during routine lab sampling, medication administration, air entrainment through the venous cannula, or via a circuit disruption. Circuit components have been designed and positioned to minimize the quantity of air that travels through the arterial line to the patient. The purpose of this study was to assess the air handling of a newer generation extracorporeal life support circuit. The extracorporeal life support circuit consisted of an open hard-shell venous reservoir, Better Bladder (BB14) or silicone bladder (R-14), and Quadrox D oxygenator or 0800 silicone oxygenator. Air emboli detection sensors were placed in the extracorporeal life support circuit: post bladder, post oxygenator, and post heat exchanger if applicable.Air was injected as a 1 mL/min for 5 minutes injection or as a single 5 mL bolus. Emboli detection was recorded continuously during and for 3 minutes post air injection at two blood flow rates (Qb) (.5 and 1.2 L/min). All tests were performed in triplicate with each condition. All tested components reduced the embolic volume transmitted through the circuit. The quantity of this reduction was dependent on both the Qb and the air injection condition. During this in-vitro testing, air emboli passing through any of the components tested was decreased. Furthermore, the emboli delivery was reduced post component with the slower Qb (.5 L/min).
Coronary artery bypass graft surgery in the elderly. Indications and outcome.
A total of 5,070 patients 65 years of age or older underwent primary elective coronary bypass surgery at The Cleveland Clinic Foundation from January 1976 through June 1986. These patients were divided by age into two groups, 65-74 years of age and 75 years and older; these groups were compared with each other and with patients younger than 65 years. With advancing age, there was a significantly greater prevalence of women, more severe angina, diabetes, peripheral vascular disease, previous cerebral events, cardiac enlargement, and left main coronary artery disease. Overall mortality during hospitalization was 2.3% and rose progressively with advancing age. Variables predictive of higher operative mortality included age >75 years, cigarette smoking, left ventricular impairment, and female gender. Perioperative myocardial infarction and wound complications showed no correlation with age, but other morbidity occurred more frequently in older patients. Stroke was more common over age 65, and postoperative atrial fibrillation rose significantly with advancing age. After a mean follow-up of 91 months, angina relief was better in the elderly than among their younger counterparts (P = 0.0001), and vein and arterial graft patency were comparable. The 10-year actuarial survival was 64% for ages 65-74 and the eight-year survival for patients 75 or older was 53%. Successful bypass surgery among the elderly conferred consistent angina relief and longevity that exceeds that of the U.S. population, matched for age and gender.