Eye-tracking analysis of skilled performance in clinical extracorporeal circulation.

The manipulation of extracorporeal circulation (ECC), which is performed by perfusionists during cardiovascular surgery, is a highly sophisticated cognitive process based on visual information obtained from information sources such as ECC indicators, surgeons, an operating field, a scrub nurse, surgical instruments, displays, patients, among others. An eye-tracking approach is expected to be a powerful means of automatic and rapid analysis. This paper presents the results of a pilot study in which an eye-tracking approach was applied to the analysis of ECC operation tasks conducted during real clinical cardiovascular surgery in the operating room. Eye-tracking data on four perfusionists were recorded while they were manipulating the ECC during a series of cardiovascular surgeries. The experience of the perfusionists ranged from 2 to 26+ years. Based on the data obtained, fixation-by-fixation cataloging of eye-tracking data in which each fixation was transcribed in timeline style was performed for each perfusionist. Gaze allocation tendencies during the surgeries for all four perfusionists were determined through a comparative analysis. It was noted that an expert engineer dispersed his attention more widely than did intermediate and novice perfusionists. Taking the results of the data analysis into consideration, we discuss the implications of well-skilled perfusionists' performance during the manipulation of ECC, as well as the principles that guide how eye-tracking data obtained in real surgery should be processed. This is the first study on the application of an eye-tracking approach to the analysis of ECC operation tasks to be reported in the Japanese literature.

Open anastomosis of extracardiac conduit for total cavopulmonary connection decreases post-operative pleural effusion.

OBJECTIVE: The goal of this study was to see whether the open anastomosis technique using vacuum-assisted venous drainage at the time of the Fontan procedure was associated with decreased post-operative pleural effusion. METHODS: We analysed a subgroup of patients with a functional single ventricle who underwent non-fenestrated total cavopulmonary connection completion with the insertion of an extracardiac conduit as the sole or predominant procedure conducted by a single surgeon at a single institute, using either an open or closed anastomosis technique. RESULTS: Median age and weight were 2.3 years, with a range from 1.3 to 27.6 years and 11.4 kilograms, with a range from 9.7 to 43 kilograms, respectively. The open anastomosis technique was associated with a shorter bypass run (p = 0.015), decreased surgical duration (p = 0.032), fewer pleural effusion days (p = 0.049), and lesser pleural effusion (p = 0.013) than closed anastomosis. Correlation analysis demonstrated a significant relationship between the amount of pleural effusion and surgical duration (correlation efficient, 0.535; p = 0.033). A logistic regression model showed that the open technique was associated with a 20-fold increase in the likelihood of having a total chest tube discharge of less than 300 millilitres (p = 0.027). CONCLUSIONS: The open anastomosis technique shortens operative duration and bypass run, which in turn might contribute to decreased pleural effusion soon after the modified Fontan procedure.

[The Japanese guidelines for cardiopulmonary bypass and recommendations concerning safety devices for cardiopulmonary bypass].

In March 2007, under the guidance of the Ministry of Health, Labour and Welfare, a committee released Japanese guidelines for cardiopulmonary bypass (CPB) with the purpose to standardize CPB hardware and software for patient's safety and education of medical personnel. In April 2007, the Japanese Society of Extra Corporeal Technology in Medicine (JaSECT) released recommendations concerning safety devices for cardiopulmonary bypass. An on-site training session for CPB troubles was held at the 38th annual meeting of Japanese Society for Cardiovascular Surgery in February 2008 as a measure to ensure safety of CPB. Young heart surgeons and perfusionists were taught the basic CPB operations, recovering procedures after an incident, and the use of safety devices. A questionnaire survey was conducted at the end of the training session. Eight heart surgeons and 7 perfusionists (3 certified and 4 without certification) participated in the session None of the 8 heart surgeons who participated had read the guidelines or made an effort to accomplish the recommendations. Of the 7 certified or uncertified perfusionists who participated, only one certified perfusionist made an effort to accomplish the recommendation. CPB accidents are rare, but as a medical team, tragedies such as death and life-threatening complication due to CPB accident should be prevented at all costs. We believe that the 1st step to prevent CPB incident is to read and understand the CPB guidelines thoroughly, and to accomplish the "required" items listed in the recommendations.

Effects of atrial fibrillation on coronary artery bypass graft flow.

OBJECTIVES: No detailed studies exist of coronary artery bypass graft flow during atrial fibrillation. We examined the effects on bypass graft flow of atrial fibrillation following coronary artery bypass grafting. METHODS: Immediately after surgical revisualization, atrial fibrillation was induced in 18 patients by high frequency atrial pacing. Hemodynamic variables were measured in sinus rhythm and atrial fibrillation. The graft flow in pedicled left internal thoracic artery grafts and in saphenous vein grafts was also measured using transit-time flowmetry. RESULTS: Left internal thoracic artery graft flow had a greater diastolic component than saphenous vein graft flow, as shown by the percent diastolic time-flow integral (86 +/- 10% in the left thoracic artery and 62 +/- 12% in the saphenous vein, P < 0.0001). The induced atrial fibrillation caused significant deterioration in hemodynamics: heart rate and central venous pressure increased, and mean arterial pressure and cardiac index decreased (all P < 0.0025). In left internal thoracic artery grafts (n = 18) and also in saphenous vein grafts (n = 20), graft flow decreased significantly with atrial fibrillation (44.3 +/- 26.2 to 26.2 +/- 20.7 ml/min in the left internal thoracic artery, P = 0.0003; 39.7 +/- 15.6 to 33.3 +/- 14.3 ml/min in the saphenous vein, P = 0.001). The reduction in graft flow due to atrial fibrillation was much larger in left internal thoracic artery grafts than in saphenous vein grafts (P = 0.0008). CONCLUSIONS: Direct measurement of coronary artery bypass graft flow shows that atrial fibrillation after surgery significantly reduces graft flow. The effect is much larger in left internal thoracic artery grafts with their strong diastolic component than in saphenous vein grafts.

Active distal coronary perfusion to prevent regional myocardial ischemia in off-pump coronary artery bypass grafting.

Regional myocardial ischemia during anastomosis in off-pump coronary artery bypass (OPCAB) can occasionally cause hemodynamic instability. To prevent regional myocardial ischemia and stabilize the hemodynamics during the procedure, perfusion of the distal coronary artery to the anastomotic site is necessary as the only reliable method. We have applied an active coronary perfusion method using a servo-controlled pump in selected patients in place of conventional passive perfusion methods (intraluminal shunt and external shunt). We present a case in which the active perfusion method proved useful in avoiding regional myocardial ischemia. A 74-year-old male patient with triple-vessel coronary disease underwent OPCAB for unstable angina. During revascularization of the main right coronary artery, the hemodynamics collapsed due to regional myocardial ischemia. As soon as the distal coronary artery was perfused at a high flow rate around 80 ml/min, the hemodynamics stabilized and the operation was completed successfully. This active coronary perfusion method in OPCAB is particularly useful in cases in which regional myocardial ischemia cause hemodynamic instability.

Resection of giant right atrial lymphoma using vacuum-assisted cardiopulmonary bypass without snaring the inferior vena cava.

A 53-year-old man sustained hemodynamic collapse due to a huge right atrial tumor and was transferred to our hospital and underwent a life-saving emergency operation. The tumor arose from the inferolateral wall of the right atrium, occupying almost the whole right atrial cavity and obstructing not only the inflow of the right ventricle but also the orifice of the inferior vena cava. Venous cannulation via the right atrial wall and placing a snare around the inferior vena cava were impossible. With a cardiopulmonary bypass using vacuum-assisted venous drainage, the tumor was successfully resected and the tricuspid valve was replaced with a bioprosthetic valve without snaring the inferior vena cava. Postoperative histological examination demonstrated the tumor to be a large B-cell non-Hodgkin type malignant lymphoma. When the tumor is large and it is difficult to establish total cardiopulmonary bypass, the vacuum-assisted cardiopulmonary bypass is a useful option. This can achieve a bloodless operative field and is not blocked by the incoming air, due to the venous drainage being continually pressure-regulated.

Total arch replacement under flow monitoring during selective cerebral perfusion using a single pump.

BACKGROUND: Flow in individual vessels is passively determined when a single pump is used for selective cerebral perfusion during aortic arch surgery. We installed a Doppler flowmeter in the circuit and measured flow in the supraaortic vessels to determine flow distribution during selective cerebral perfusion. METHODS: We cannulated and perfused three supraaortic vessels using a single pump in 203 patients who underwent elective (n = 158) or emergency or urgent (n = 45) total arch replacement using a four-branched prosthetic graft. Flow rates in each branch were continuously monitored during selective cerebral perfusion. RESULTS: The respective mean flow rates in the brachiocephalic, left common carotid, and left subclavian arteries and total flow rates were 5.8, 3.3, 3.4, and 12.5 mL·kg(-1)·min(-1). The ratios of flow in these vessels to total flow were 46.5%, 26.5%, and 27.0%, respectively, and they were not affected by the total flow rate. In-hospital mortality rates among the patients who underwent elective and emergency or urgent surgery were 1.9% (n = 3) and 11.1% (n = 5), respectively, and the rates of postoperative stroke were 2.5% (n = 4) and 8.9% (n = 4), respectively. Total flow in the supraaortic vessels during selective cerebral perfusion was significantly lower in patients with neurologic complications than in those without (732 versus 806 mL/min; p = 0.034). CONCLUSIONS: Flow monitoring showed that selective perfusion using a single pump adequately distributed flow among all supraaortic vessels. This monitoring system might help to improve brain protection and outcomes during total aortic arch replacement.

Comparison of active and passive coronary perfusion in off-pump coronary artery bypass grafting.

The myocardial protective effects of active and passive coronary perfusion were compared during off-pump coronary artery bypass grafting (OPCAB) in coronary stenosis model. An internal shunt tube was placed in the proximal left anterior descending arteries of adult dogs to produce a 75% coronary stenosis model. In 10 animals passive coronary perfusion was performed using an internal shunt tube placed in a pseudo-anastomotic site, and active coronary perfusion was performed through an external shunt tube. Ischemia was examined at normal and low blood pressure, based on hemodynamics, regional myocardial blood flow, and oxygen and lactate extraction in the perfused area. With passive perfusion, regional myocardial blood flow decreased and oxygen extraction and regional lactate production increased at normal blood pressure, indicating myocardial ischemia. Regional myocardial blood flow further decreased at low blood pressure. In contrast, regional myocardial blood flow with active perfusion did not change at normal or low blood pressure, and oxygen and lactate extraction were unchanged, indicating prevention of myocardial ischemia. Myocardial ischemia can occur with passive perfusion even at normal blood pressure. Active coronary perfusion that provides sufficient regional perfusion prevents myocardial ischemia during coronary artery anastomosis in OPCAB.

Quantitative evaluation of hand cranking a roller pump in a crisis management drill.

The heart-lung machines for open-heart surgery have improved over the past 50 years; they rarely break down and are almost always equipped with backup batteries. The hand-cranking procedure only becomes necessary when a pump breaks down during perfusion or after the batteries have run out. In this study, the performance of hand cranking a roller pump was quantitatively assessed by an objective method using the ECCSIM-Lite educational simulator system. A roller pump connected to an extracorporeal circuit with an oxygenator and with gravity venous drainage was used. A flow sensor unit consisting of electromagnetic sensors was used to measure arterial and venous flow rates, and a built-in pressure sensor was used to measure the water level in the reservoir. A preliminary study of continuous cranking by a team of six people was conducted as a surprise drill. This system was then used at a perfusion seminar. At the seminar, 1-min hand-cranking drills were conducted by volunteers according to a prepared scenario. The data were calculated on site and trend graphs of individual performances were given to the participants as a handout. Preliminary studies showed that each person's performance was different. Results from 1-min drills showed that good performance was not related to the number of clinical cases experienced, years of practice, or experience in hand cranking. Hand cranking to maintain the target flow rate could be achieved without practice; however, manipulating the venous return clamp requires practice. While the necessity of performing hand cranking during perfusion due to pump failure is rare, we believe that it is beneficial for perfusionists and patients to include hand-cranking practice in periodic extracorporeal circulation crisis management drills because a drill allows perfusionists to mentally rehearse the procedures should such a crisis occur.

Total cavopulmonary connection: open anastomosis of an extracardiac conduit with vacuum-assisted venous drainage.

Insertion of a tube conduit for total cavopulmonary connection is sometimes technically demanding due to the crumpled stump of the inferior vena cava caused by a tourniquet of the inferior vena cava near the division line. Herein we describe an alternative in which the anastomosis is completed during removal of the tourniquet with the application of vacuum-assisted venous drainage. This new technique may alleviate, if not completely eliminate, a concern associated with total cavopulmonary connection with extracardiac conduit in small patients.

A case in which biventricular assist device support was required after aortic valve replacement with a bioprosthetic valve.

We report the case of a 45-year-old man with severe aortic regurgitation. The patient underwent aortic valve replacement with a bioprosthetic valve, but was unable to be weaned from cardiopulmonary bypass (CPB). Intraoperative coronary angiography revealed stenosis of the right coronary orifice, so an intra-aortic balloon pump was inserted and coronary artery bypass grafting to the right coronary artery was conducted; however, weaning from CPB again failed. Left ventricular assist using a Gyro centrifugal pump was performed between the left atrium and left femoral artery, along with right ventricular assist using a Nikkiso centrifugal pump between the right atrium and pulmonary artery. Flow rates averaged from 2.0 to 2.8 l/min for the left-side ventricular assist device (VAD) and 2.1-3.8 l/min for the right-side VAD. The bypass rate reached approximately 70% at maximum. No thromboembolic events were documented during VAD support. The patient underwent explantation of VADs on postoperative day 4. No thrombus was identified on the bioprosthetic aortic valve by transesophageal echocardiography. The left-side pump displayed no thrombus, while the right-side pump had a small thrombus at the shaft. The patient was discharged from the hospital and was alive as of 2 year postoperatively. To the best of our knowledge, no clinical study has yet compared the antithrombotic properties of two centrifugal pumps in one patient where mechanical support was performed for the same duration and flow rate.