Cardiopulmonary bypass venous cannulation challenges in a paediatric patient with complex congenital heart disease: a case report.

When choosing cannulae for cardiac surgery the two most important factors to be considered are the proposed procedure and the patient anatomy. These factors are especially crucial in paediatric patients with congenital heart disease. A 3-year-old, 14-kg male presented to the University of Iowa Hospitals and Clinics with dextro-transposition of the great arteries, atrioventricular canal, left pulmonary stenosis, azygous continuation, bilateral superior vena cavae, partial anomalous pulmonary venous return, left aortic arch and status post-right Blalock-Taussing shunt. The complex anatomy presented a surgical dilemma. The course of surgical intervention was determined, a variation of the modified Fontan procedure, and the anatomy of the patient was directly viewed. The surgeon concluded that four venous cannulae were required to provide adequate venous return for the cardiopulmonary bypass (CPB) circuit and a bloodless surgical field. The operation was successfully performed under mild hypothermia with no complications. The patient fully recovered with only mild restrictions on his activity level. This case acutely illustrates the importance of anatomical and procedural awareness when choosing cannulae and cannulation sites for CPB in paediatric patients with congenital heart disease.

Correlation of ACT as measured with three commercially available devices with circulating heparin level during cardiac surgery.

Automated activated clotting time (ACT) is utilized as the primary means of assessing anticoagulation status for cardiopulmonary bypass (CPB) procedures. Influences on the clotting cascade during CPB such as hypothermia, hemodilution, and platelet dysfunction are known to affect ACT. The recently introduced Thrombolytic Assessment System (TAS) has been reported to be less sensitive to changes in hemodilution and hypothermia during CPB than more conventional ACT devices. This study evaluated the ability of TAS, and two other commercially available automated ACT systems, the HemoTec and Hemochron, to correlate with circulating heparin levels. Reference standards for circulating heparin were determined by inactivation of factor Xa assay. Nineteen patients undergoing moderate hypothermic CPB served as subjects for this investigation. Blood samples were obtained for study at four time periods: 1) baseline (control), 2) post heparin administration (300-400 U/kg) prior to CPB, 3) during CPB, and 4) post protamine. Study results demonstrated a high correlation between the HemoTec and Hemochron (r = 0.99), increased heparin dose response on CPB compared to pre-CPB activity (p < 0.05), and a significant (p < 0.05) negative correlation between devices and patient hematocrit during CPB. Additionally, device correlation with anti-Xa assay during collection periods 2 and 3 showed negative correlations in each of the three devices evaluated. We conclude that all automated devices tested demonstrated an inability to predict circulating heparin at levels necessary for CPB, and that these discrepancies become magnified during CPB procedures.

Evaluation of five in-line hematocrit monitors.

Monitoring the hematocrit is essential during cardiopulmonary bypass for efficacious administration of blood products. The purpose of this study was to evaluate five cardiopulmonary bypass in-line monitors designed to display continuous hematocrit or hemoglobin values. The devices were evaluated for accuracy using an in vitro circuit primed with human blood while randomizing hematocrit, blood flow rate, and temperature. Hematocrits correlated significantly with the error in all the devices (p < 0.01). Over evaluation time, the error of the CDI, Gish, IBC, and MX2 increased significantly (p < 0.05). Temperature correlated significantly with the error of the Gish device (r = -0.49, p < 0.01). Blood flow correlated significantly with the Gish error (r = -0.24, p < 0.01). The Cobe device had a significantly smaller overall error than the other devices (p < 0.001). Device evaluation, based on a low mean error, a low percent error, a high correlation with the actual hematocrit, low correlations between mean error, blood flow, and temperature, and insignificant correlation between time and error, suggests that the Cobe device is more accurate for the continuous monitoring of hematocrit during cardiopulmonary bypass.

Oxygenator evaluation: Maxima 1380 versus Maxima Plus.

Continual improvement of oxygenators has been important in the growing demands of patient safety and support during cardiopulmonary bypass. The purpose of this study was to compare the Maxima 1380 oxygenator to the upgraded Maxima Plus oxygenator. Thirty-two adult patients were randomized to either the 1380 group or the Plus group. Information was recorded on the patients' weight, age, body surface area, esophageal temperature, arterial temperature, venous oxygen saturation, arterial pO2, arterial pCO2, blood flow, hematocrit, gas sweep, and FiO2. No significant difference was found between the two groups' mean weight, body surface area, arterial pO2 arterial pCO2, age, esophageal temperature, arterial temperature, venous oxygen saturation, and blood flow (p > 0.05). The Plus group demonstrated significantly lower mean gas sweep rates and FiO2 settings than the 1380 group. FiO2 of the 1380 was dependent on age, body surface area, blood flow, and esophageal temperature (r = 0.89, p < 0.001). FiO2 of the Plus was correlated with weight, esophageal temperature, arterial temperature, and arterial pO2 (r = 0.93, p < 0.001). Gas sweep rate of the 1380 was dependent on age, weight, esophageal temperature, blood flow, arterial temperature, and arterial pCO2 (r = 0.84, p < 0.001). The gas sweep rate of the Plus was dependent on weight and esophageal temperature (r = 0.55, p < 0.001). Based on these analyses, the new Maxima Plus oxygenator is more efficient in oxygen and carbon dioxide transport than the Maxima 1380.

Evaluation of a rapid infusion system.

Operative cases where there is a potential for massive blood loss necessitates a system to rapidly warm and transfuse large volumes of blood over short periods of time. An in-house system in which both crystalloid solutions and blood products can be quickly added, warmed and available for infusion was developed to meet this need. The purpose of this study was to evaluate how blood products are affected when warmed and recirculated for an extended period of time. A recirculating rapid infusion system was assembled utilizing two filtered cardiotomy reservoirs, a centrifugal pump, a stainless steel blood heat exchanger, and 1/4 inch tubing, and applied in six adult orthotopic liver transplantations. The system was primed with 2 to 4 units each of fresh frozen plasma and packed red blood cells. The prime was recirculated and warmed to 37 degrees C. Samples for blood gases, oxygen saturation, hematocrit, plasma free hemoglobin, sodium and potassium levels were drawn after initial priming and then every 30 minutes until additional blood products were added. Results show no significant change in pH (6.57 +/- 0.21), pO2 (56 mmHg +/- 23 mmHg), pCO2 (173 mmHg +/- 138 mmHg), hematocrit (27% +/- 8.7%) and plasma free hemoglobin values (125 mg/dl +/- 9.4 mg/dl), following 3 hours of recirculation. However, potassium levels significantly decreased from 11.6 meq/L +/- 2.6 meq/L to 10.0 meq/L +/- 2.3 meq/L (p < 0.05), sodium levels significantly increased from 144 meq/L +/- 5.9 meq/L to 147 meq/L +/- 5.3 meq/L (p < 0.05) and oxygen saturations significantly increased from 59% +/- 9.1% to 70% +/- 16% (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The impact of computers on patient care and research: the pentobarbital coma experience.

Computer applications to patient care in an intensive care unit are examples the potential computers hold for health care, education, and research. The clinical application of a computer system to research and patient care in a selected research population, the pentobarbital coma study group, is described. The computer has been valuable in research for its data collecting and processing capabilities. It has also allowed the nursing staff to devote more time to patient care activities.