Oxygenator failure.
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Cardiopulmonary Bypass↗
Biomedical subjects
M Kurusz
Publications and source records attributed to M Kurusz.
Devices and monitoring during neonatal ECMO: survey results.
A survey of active ECMO centres regarding neonatal ECMO equipment and personnel was obtained by telephone interview in late summer 1989. Forty-seven of the centres in the USA listed in the Ann Arbor ELSO (Extracorporeal Life Support Organization) Registry at the time ( greater than 90%) were contacted and all participated. Nearly all use a roller pump, while less than 5% use a centrifugal pump. All programmes use a SciMed membrane oxygenator and 90% a SciMed heat exchanger. Heat exchanger water sources include the Gaymar T-pump (42%), Seabrook (25%) and Cincinnati Sub-Zero (23%) units. Eighty-seven per cent use a bladder box servo-regulated to the roller pump; these are most often custom-made (69%) but 13% of programmes use a commercially available (Seabrook) bladder box. Ten per cent use a pressure-regulated roller pump rather than a conventional (displacement) bladder box to detect decreases in venous return. Nearly 80% monitor circuit line pressures between the pump and patient. Seventeen per cent use an air bubble detector on the arterial side of the circuit. Only 10% use an arterial bubble trap and 6% an arterial line filter. Seventy-five per cent do not monitor gas line pressures into the membrane lung, but one-third do use a gas line pop-off valve to prevent elevated gas phase pressures. Seventy per cent reported use of continuous in-line measurement of mixed venous oxygen saturation; no programme reported any blood chemistries being monitored in line.(ABSTRACT TRUNCATED AT 250 WORDS)
Data Collection↗
Surface tension effects of heparin coating on arterial line filters.
An investigation was conducted to determine the effects that heparin-coated screen arterial line filters have on the surface tension of cardiopulmonary bypass (CPB) priming solution. Five brands of non-heparin coated arterial line filters (Bard H625, Bentley AF1040, Intersept 40mum, Pall EC3840 and Pall SP3840) and four brands of heparin-coated filters (Bard H640, Bentley AF1040C and AF1040D and Intersept 40mum) were tested in a closed-loop circuit containing two litres of Plasma-Lyte A and pumped at a rate of five litres per minute. Samples were collected at 0.5, 20, 60 and 120 minutes to determine the surface tension of the recirculated solution. The non-heparin coated arterial line filters showed no significant changes in surface tension, either between the individual groups or over time. The benzalkonium-heparin coated filters (Bard H640, Bentley AF1040C and Intersept 40mum) all showed significant decreases in surface tension when compared to zero circulation time or to the noncoated groups. The largest drop in surface tension occurred within the first five minutes of recirculation. The circuit with a Bentley AF 1040D (a new nonbenzalkonium process) coated filter showed no significant change in surface tension.
Benzalkonium Compounds↗
Risk containment during cardiopulmonary bypass.
It is evident that positive attitudes towards patient care are the cornerstone of risk containment during CPB. Positive attitudes are shaped by education and training, including continuing education. Mutual respect among team members can foster positive attitudes that are manifested in an orderly, quiet operating room, with those present always mindful of the patient's welfare. Vigilance is the key in preventing complacency during CPB procedures that have now become routine. Collins writes that the best airplane pilots develop a curious and suspicious attitude in the cockpit and, again, the applicability of the aviation and perfusion analogy is apparent. Monitors, standards, protocols, and safety devices can never fully replace vigilance in overcoming human frailty or error. Vigilance has been defined as "a state of clinical awareness whereby dangerous conditions are anticipated or recognized and promptly treated." Stoelting further writes that levels of vigilance may be reduced by extraneous distractions, fatigue, and stress. Gaba et al have studied anesthetic mishaps in the context of accident investigations in unrelated fields and have suggested two responsibilities in breaking the chain of accident evolution. The first is to scrutinize our own abilities and limitations ... and implement the procedures and training that can be shown to optimize patient safety, and second ... to reexamine the entire structure of our industry, attempting to steer the interacting sources of incentive and constraint towards a system that promotes patient safety. Guides to acceptability of risk include the twin tenets of reasonableness and custom of usage, prevailing professional practice, the best available practice, and the degree of necessity or benefit.(ABSTRACT TRUNCATED AT 250 WORDS)
Cardiopulmonary Bypass↗
Effect of the Trendelenburg position on the distribution of arterial air emboli in dogs.
We examined the effects of buoyancy on the distribution of arterial gas bubbles using in vitro and in vivo techniques in dogs. A simulated carotid artery preparation was used to determine the effects of bubble size and vessel angle on the velocity and direction of bubble movement in flowing blood. Because buoyancy tends to float bubbles away from dependent areas, bubble velocity would be expected to decrease as the vessel angle increased. We found that larger bubbles increased in velocity in the same direction as the blood flow at 0-, 10-, and 30-degree vessel angles and decreased when the vessel was positioned at 90 degrees. Smaller bubbles did not change velocity from 0 to 30 degrees and increased in velocity in the same direction as blood flow at 90 degrees. In 10 anesthetized dogs, we studied the effects of 0-, 10-, 15-, and 30-degree Trendelenburg's position on carotid artery distribution of gas bubbles injected into the left ventricle or ascending aorta. Regardless of the degree of the Trendelenburg position, the bubbles passed into the carotid artery simultaneously with passage into the abdominal aorta. We conclude that the forces of buoyancy do not overcome the force of arterial blood flow and that the Trendelenburg position does not prevent arterial bubbles from reaching the brain.
Animals↗
Fluorocarbon treatment for cerebral air embolism.
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Animals↗
A technique for cardioplegic infusion and left heart venting during coronary artery bypass grafting.
A method for administering cardioplegia and venting the left heart that utilizes a single cannula in the aortic root and minimizes the risk of air entering the left heart is presented. This technique permits precise control of flow and pressure of the cardioplegic solution. Left heart decompression is accomplished by siphon drainage with controlled negative pressure. This method effectively vents the left heart while preventing aspiration of air around the cannula insertion site or retrograde through an opened coronary artery with a nonocclusive proximal lesion during the construction of the distal anastomoses.
Aorta↗
Use of cold cardioplegic solution for vein graft distention and preservation: a light and scanning electron microscopic study.
To evaluate the effect of a cardioplegic solution on the endothelium of the saphenous vein, portions of this vein were harvested from each of 5 patients undergoing coronary artery bypass operation. Each sample was divided into five segments. One segment was distended with heparinized saline solution, one with heparinized blood, and one with heparinized cardioplegic solution (25 mEq of potassium per liter). All of the distending solutions were kept at 10 degrees C, and pressure was carefully limited to 200 mm Hg. The fourth segment of vein was distended with heparinized saline solution but no effort was made to limit distending pressure, and the fifth segment was not distended. All samples were then examined with light and scanning electron microscopy. There were no great morphological differences in the endothelium of veins distended to 200 mm Hg with saline solution, blood, or cardioplegic solution. The morphology of these samples compared favorably with the control vein endothelium although scattered areas of endothelial disruption were present in every sample. Veins distended without pressure control showed massive endothelial disruption. The particular solution used to distend the sephenous veins is not as important as limiting the distending pressure.
Blood↗
Suppression of a demand pacemaker in the presence of redundant transvenous right ventricular leads.
A ventricular inhibited demand cardiac pacemaker was inhibited in the presence of intimate contact between the active temporary bipolar electrode ring and a retained inactive permanent bipolar electrode tip. Electromagnetic interference effects, lack of insulation, lead breaks, and loose connections were all ruled out as the cause of pacemaker suppression.
Electrodes, Implanted↗
Runaway pump head: new cause of gas embolism during cardiopulmonary bypass.
Massive gas embolism was narrowly avoided during a recent case of cardiopulmonary bypass for aortic valve replacement. Cause of the mishap was an arterial pump head that had rapidly accelerated spontaneously, emptying the oxygenator of blood within seconds. No gas entered the patient's vascular system, but a period of circulatory arrest was required in order to purge the extracorporeal circuit of gas and to re-establish blood flow. Only an instantaneous response by the perfusionist prevented massive gas embolism.
Cardiopulmonary Bypass↗
Similarity of clinical and laboratory results obtained with microporous teflon membrane oxygenator and bubble-film hybrid oxygenator.
For 80 elective clinical cardiopulmonary bypasses we alternately used either a commercial microporous Teflon membrane oxygenator or a commercial hybrid bubble-film oxygenator. Setup time was a little longer with the membrane unit (20 minutes), but priming volume (2,250 ml) was the same. No problems were encountered with the hybrid oxygenator. However, despite our monitoring of additional variables, including shim and inlet pressure and recirculation flow, gas exchange abnormalities were encountered in 5 patients on whom the membrane oxygenator was used; in 4 of these cases the abnormalities were encountered prior to our recognition of the potential for occasional internal shunting with this device. There were no hospital deaths. When the two groups, matched except for oxygenator selection, were compared, there were no significant differences clinically or hematologically. For cardiopulmonary bypass of 2 hours or less, both oxygenators studied are definite improvements over previous silicone membrane and high-gas-flow bubble oxygenators. However, lower cost and reduced complexity favor the hybrid oxygenator.
Blood Glucose↗
Preliminary clinical experience with isotonic hypothermic potassium-induced arrest.
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Adolescent↗
Reversal of anticoagulation without protamine using a heparin removal device after cardiopulmonary bypass.
Protamine sulfate is routinely administered after cardiopulmonary bypass to reverse systemic heparinization, but may cause a severe hypotensive reaction in as many as 2% of patients. Research Medical, Inc., has developed an extracorporeal venovenous heparin removal device (HRD) for use in patients at high risk for a protamine reaction. Circulation through the HRD removes heparin by hollow fiber plasma separation and selective sorption of anionically charged heparin to a polycationically charged poly-L-lysine ligand coupled to a agarose substrate. The heparin depleted plasma then reenters the whole blood pathway and is returned to the patient through the double lumen catheter in the right atrium. To evaluate the HRD in a clinically relevant model, cardiopulmonary bypass was performed in pigs using RA-Ao cardiopulmonary bypass (120 min) with systemic heparinization (300 IU/kg), a nonpulsatile pump with a membrane oxygenator, and systemic hypothermia (28 degrees C). Group 1 (HEP n = 7) had no intervention to neutralize the heparin; Group 2 (HRD n = 7) used the HRD. After 19.7 +/- 4.2 min of circulation through the HRD, the activated clotting time had returned to baseline, whereas the pigs in the HEP group were still anticoagulated (activated clotting time = 396 +/- 152 sec; time to baseline was 124 +/- 9 min). There were no significant differences between groups with respect to hemodynamics, hematocrit levels, leukocyte profiles, or platelet counts, HRD is an effective heparin removal device in a pig model of cardiopulmonary bypass and awaits a phase I clinical trial in humans.
Animals↗
Gaseous microemboli: sources, causes, and clinical considerations.
Patients undergoing open-heart surgery are exposed to gaseous microemboli (GME) from several sources, including bubble oxygenators, which are used in a majority of cases for cardiopulmonary bypass. If present in large quantities, GME can reduce blood flow and delivery of oxygen to tissues and may be responsible, in part, for some of the complications that commonly follow cardiopulmonary bypass. Gaseous microemboli are defined, and the causes of this phenomenon are examined. The literature from the last 30 years on this topic is also reviewed, and measures for reducing GME during cardiopulmonary bypass are recommended. Current considerations for users of cardiopulmonary bypass systems are discussed, and five unanswered questions are raised in the conclusion.
Cardiopulmonary Bypass↗