Perfusion Error Cause Removal: The Perfusion Case Conference

Prevention of accidents is one of the fundamental elements of perfusion quality. Unfortunately, errors and accidents frequently occur during cardiopulmonary bypass. A recent retrospective survey of perfusionists identified some common accidents. We have previously reported a method of developing protocols to prevent and treat the ten most common perfusion related problems. Until we reach the day when perfusion accidents no longer occur, we need to be able to systematically evaluate failures and prevent their recurrence. We have developed a non-judgmental forum to discuss, analyze, and prevent variances or unusual circumstances that occur during cardiopulmonary bypass. We hold a monthly case conference where we discuss all cases from which we can learn something–interesting cases and cases during which there was a departure from protocol. The purpose of this paper is to discuss the development of a case conference and to outline the format and benefits of such an Error Cause Removal program

The Biomedical Technology/Information Explosion: Find Yourself A Foxhole

Approximately 5500 biomedical papers are published every day and the half-life of this information is currently only 3-4 years. Therefore, it is not only important but nearly impossible to keep up-to-date on the literature relating to one's field. This paper will propose a Journal Club (JC) format designed for perfusionists. Our experience with JC the last three years encourages us to share what we have learned about design, scheduling, benefits, pitfalls, and the evolution of a JC. We will suggest a list of 50+ journals that represent a cross section of the literature from disciplines affecting perfusionists. We will discuss techniques for surveying the literature, reporting at JC, recording participation, and creating a database for reference. JC is the best way to stay current with new information in our field and the benefits justify the effort required

A Technique for the Effective Removal of Air from a Hollow Fiber Membrane Oxygenator Circuit

This paper describes some of the ways unwanted air can be introduced into a cardiopulmonary bypass circuit and a technique which has been shown to significantly decrease the resultant bubble counts. In this study air was introduced into a circuit (Hct. 20%) containing a Hollow Fiber Membrane Oxygenator (HFMO). Conventional techniques of recirculation (3 L/min.) and vigorous agitation/percussion were compared to recirculation with vacuum (gas phase of HFMO) for efficiency in reducing bubble counts measured after three minutes by a microbubble counter. Conventional methods were ineffective after three minutes while vacuum for 3 minutes significantly (p = .001) reduced bubble counts (bubbles > 100 microns). The microporous membrane allows efficient air removal with vacuum while recirculation/percussion did little to remove air which, in a blood perfusate, was not visible to the naked eye. The application of vacuum not only increases safety but convenience when used in the priming and de bubbling of a circuit in routine and emergency case

An Experimental Evaluation of the Capiox 1.6 and 5.4M

Membrane oxygenators do not create bubbles but most will transmit the bubbles which are common in venous reservoir bags. We previously reported the elimination of arterial micro-air in the 0.8m2 Capiox when operated in the inverted position with an open purge line. This same lung failed to eliminate micro-air when operated in the conventional orientation. The purpose of this study was to test the effectiveness of the Capiox as a bubble trap in lungs with a larger surface area (subgroup a-1.6m2) (subgroup b-5.4m2) and at higher flows. Two test circuits were constructed for each size lung (Group 1—conventional orientation) (Group 11—inverted). The circuits were primed with dilute, outdated human blood (Hct. 20 ± 2%). Ten injections of air (5ml) were done for each lung in both test positions. A bubble counter on the outlet side of the lung was used to count bubbles passed through the membrane oxygenator following the air challenge. Thirty second counts were significantly higher (p<.001) in Group I than in Group II for both size lungs. The counts for both groups were: Group I(alb

An In Vitro Comparison of Micro Air Passage in the Venous Reservoir Bag

The increasing use of membrane oxygenators and collapsable venous reservoir bags (VRB) imposes a concern not associated with bubble oxygenators: Venous line air. Since no defoamer is present, a VRB must rely on flow characteristics or a barrier to remove air from the venous return. The purpose of this study is to determine the air removal efficiency of seven commercially available VRBs. Seven VRBs with clear crystaloid solution were tested for microbubble passage using an ultrasonic bubble detector at the outlet. At 5 LPM flow, 50cc of air was injected into a stopcock in the venous line. Microbubble counts were taken in six trials of each bag, and divided into three size ranges: 10–50µ, 50–100µ, and >100µ. The means and standard deviations are presented below. VR

A Double-Lumen Cannula for Cardioplegia Delivery and/or Air Aspiration from the Aorta during Cardiopulmonary Bypass

This paper reports the use of a double-lumen cannula designed to deliver cardioplegic solution, decompress the left heart during ischemic arrest, and aspirate air from the aorta before cardioplegic delivery and after the aortic cross-damp is removed. The unique feature of this cannula is its doublelumen design which allows air to be aspirated from the aorta prior to, and concurrent with, the beginning of the delivery of cardioplegic solution, to prevent the introduction of air into the coronary arteries. We will outline the unrecognized sources of this air and why it is advantageous to evacuate it before a subsequent infusion of cardioplegia

Is Your Oxygenator Failing? Diagnosis and Suggested Treatment

(J. Extra-Corpor. Technol. 19[3] p. 330-337 Fall 1987, 3 ref.) Oxygenator failure during open heart surgery can be a serious complication but one with which perfusionists should be prepared to deal. We hypothesize that oxygenators are often replaced unnecessarily and when they are performing within the manufacturers' specifications. This suspicion was confirmed by surveying several oxygenator manufacturers. Discriminating between oxygenator and nonoxygenator problems is critical. In the face of the correct diagnosis of oxygenator failure a simple, safe, expedient, and familiar method of replacement is needed. By using the gas transfer equations one can determine if the oxygenator is transfering adequate gas, after other associated problems are considered and ruled out. After oxygenator failure has been diagnosed, a plan for replacement which has previously been established and practiced should be implemented. We studied 2 techniques for hollow fiber membrane oxygenation (HFMO) replacement and found the risk of micro-air, as a result of the changeout procedure, decreased when the new oxygenator was vacuumed. The purpose of this paper is to help identify when/if an oxygenator is failing and suggest a planned replacement drill to help minimize confusion, delay and possible complications. We will also present a technique for decreasing the risk of micro-air which may result from a quick oxygenator changeout

Micro-Prime Circuit Facilitating Minimal Blood Use during Infant Perfusion

(J. Extra-Corpor. Technol. 19[3] p. 352-357 Fall 1987, 24 ref.) There is considerable concern about the use of blood products during cardiac surgery on the part of adult patients and the parents of pediatric patients. It has been fairly easy to eliminate blood usage in most adult patients but difficult to impossible in infants and small children. Most infant perfusion circuits require a priming volume of 500-850cc which may be cut to 400cc with substantial effort. These volumes are far in excess of the blood volume of most newborns requiring cardiac surgery. We have developed and refined a circuit using commonly available components that can be primed with as little as 265cc. The circuit consists of a Capiox II 0.8m2 lung, with a Terumo 1 OOcc venous reservoir bag and 1/4″ lines. It incorporates a level sensor, bubble detector, recirculation line, arterial GasSTAT™ sensor, and sampling and pressure monitoring lines. A priming volume this low facilitates minimal blood usage in even the smallest infants. This circuit is especially applicable for use with children of Jehovah's Witness parents. It is unique from a safety standpoint in that it not only allows level sensing and bubble detection, but the lung is inverted so the inlet is at the top and the outlet is at the bottom. This configuration causes the lung to act as a bubble trap which may decrease gaseous microemboli. We will describe this “microprime” circuit allowing minimal or no blood usage in this age group, including a review of the literature concerning the safe limits of hemodilution

Intra-Aortic Balloon Counterpulsation for the Treatment of Ischemic Stroke

Colloid volume expansion has been shown to increase cerebral blood flow to ischemic brain in an animal stroke model and improve recovery in patients. It is, however, potentially hazardous to use in older patients because of frequently associated cardiovascular disease. Intra-Aortic Balloon Counterpulsation might reduce the risks of using volume expansion therapy in the elderly patient. This study was designed to see if Intra-Aortic Balloon Counterpulsation (without volume expansion), in an animal with a normal heart, would increase cerebral blood flow and EEG activity in the ischemic brain. Unilateral cerebral ischemia was produced in baboons (n = 9) after right middle cerebral artery occlusion. A 12 ml intra-aortic balloon catheter was introduced into the descending aorta via the femoral artery prior to middle cerebral artery occlusion. The balloon was positioned distal to the origin of the left subclavian artery and following middle cerebral artery occlusion was inflated with each R wave on the ECG. Cardiac output, cerebral blood flow (by Hydrogen wash-out), computer-mapped EEG, and hemodynamic data were collected prior to middle cerebral artery occlusion and following occlusion both before and during counterpulsation. Intra-Aortic Balloon Counterpulsation produced a significant increase in pulse pressure from 54.7 ± 21 to 70.6 ± 33 mmHg (p = .043). No significant change was seen in cardiac output, mean arterial pressure, or cerebral blood flow. Although the computer- mapped EEG improved and the right (ischemic) hemisphere cerebral blood flow did increase slightly from 16.9 ± 6.5 to 18.3 ± 8.3 ml/100 gm/min, the cerebral blood flow changes were not significant (p=.295). It is possible that the desired increase in cerebral blood flow was not achieved partly because the animals were only 3-4 years old and were difficult to stroke. We believe that there is merit to a follow-up study in older primates with colloid volume expansion where Intra-Aortic Balloon Counterpulsation is used to protect the heart from the deleterious effects of volume expansion and where the cardiac effects of volume expansion and counterpulsation are quantified. Perhaps volume expansion with Intra-Aortic Balloon Counterpulsation will be safer and more effective than either treatment modality alone. (All data reported as mean ± standard deviation

Differences in Cerebral Blood Flow with Pulsatile and Nonpulsatile Flow in Normal and Ischemic Brain

The effect of pulsatile versus non pulsatile perfusion on regional cerebral blood flow (CBF) was tested in a canine model with and without focal ischemia. Nine dogs were placed on total cardiopulmonary bypass with a flow rate of 100 cc/kg/min. at normothermia. Control cerebral blood flow measurements were made in both cerebral hemispheres using the hydrogen clearance technique during pulsatile and nonpulsatile perfusion. The cerebral blood flow measurements were repeated after lateralized ischemia was induced by occluding one middle cerebral artery and the ipsilateral carotid artery. Ischemia was confirmed by cerebral blood flow measurements and electroencephalograph changes in these anesthetized animals. In non-ischemic brain, pulsatile perfusion increased cerebral blood flow 19% over that measured during nonpulsatile perfusion. The reduced flow seen with nonpulsatile perfusion never fell into ischemic ranges (i.e., below 25 cc/100 g/min.) in normal brain tissue. However, in brain rendered ischemic by occlusion of conductance vessels, pulsatile perfusion increased cerebral blood flow 55% over nonpulsatile perfusion, presumably by recruiting collaterals more effectively. This study suggests important physiologic benefits from pulsatile perfusion, especially to patients on cardiopulmonary bypass with cerebrovascular insufficiency