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.

Renal considerations, dialysis, and ultrafiltration during cardiopulmonary bypass.

Patients with preoperative renal insufficiency are more likely to develop postoperative renal failure than those with normal preoperative renal function. Both of these groups may benefit from optimizing intraoperative renal perfusion because not all preoperative renal risk factors are easily diagnosed. Patients with preoperative chronic renal failure who are unable to manage perioperative electrolyte levels, excess water, and uremic toxins may benefit from intraoperative dialysis. Ultrafiltration is valuable in removing excess plasma water during CPB. Modified ultrafiltration studies suggest that ultrafiltration post-CPB can improve postoperative patient outcomes and that the mechanism for these improvements involve more than excess water removal. Since there are no contraindications for ultrafiltration or dialysis during CPB, the decision to use these techniques depends on the perceived potential benefits and the cost of adding a component to the CPB circuit.

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.

Comparison of gaseous microemboli counts in arterial, simultaneous and venous heat exchange with a hollow fiber membrane oxygenator.

Potential sources of gaseous microemboli during cardiopulmonary bypass are varied. However, it is known that membrane oxygenators generate fewer gaseous microemboli than bubble oxygenators and that bubblers cannot utilize arterial heat exchange without generating significant gaseous microemboli during rewarming. A membrane oxygenator utilizing simultaneous gas and heat exchange raises the concern that concurrent gas and heat exchange would result in a higher production of gaseous microemboli compared to conventional venous heat exchange devices. This in vitro study compared venous, simultaneous, arterial and control (venous) heat exchanger gaseous microemboli counts during rewarming. No significant difference was found between the four heat exchangers when comparing inlet and outlet gaseous microemboli counts. This in vitro study suggests that there is no difference in gaseous microemboli generation when varying the position of the heat exchanger in the extracorporeal circuit incorporating a microporous membrane oxygenator.

Comparison of three blood-processing techniques during and after cardiopulmonary bypass.

The return of extracorporeal circuit blood at the termination of cardiopulmonary bypass is an important feature of blood conservation during open heart procedures. However, the relative benefits and disadvantages of different circuit blood salvage methods remain unclear. Accordingly, the purpose of this study was to examine whether quantifiable differences exist between three different circuit blood-salvaging techniques: direct infusion, centrifugation, and ultrafiltration. Sixty patients with very similar preoperative characteristics were randomly assigned to each of the three groups, and blood coagulation screens, plasma profiles, and respiratory function were determined at 20 minutes and at 6 and 18 hours after cardiopulmonary bypass. Early after cardiopulmonary bypass (20 minutes), the plasma colloid osmotic pressure and fibrinogen and platelet concentrations were significantly higher with ultrafiltration (p < 0.05) versus those observed for the other two methods. The plasma thromboplastin times were significantly (p < 0.05) longer after cardiopulmonary bypass with centrifugation as compared to direct infusion and ultrafiltration. However, the coagulation profiles and plasma composition normalized by 18 hours after cardiopulmonary bypass with all three blood-salvaging methods. There were no significant differences in terms of blood utilization or chest tube drainage over the entire postoperative period among any of the circuit blood-salvaging methods. These results suggest that ultrafiltration of postcardiopulmonary circuit blood may preserve plasma colloid pressure and platelet concentration in the early postoperative period, but these differences do not persist. Thus, for routine cardiopulmonary bypass procedures, direct infusion, centrifugation, and ultrafiltration may all be satisfactory methods of circuit blood salvage.

Clinical accuracy of continuous hemoglobin oxygen saturation monitoring devices.

Three devices used to measure hemoglobin oxygen saturation in the extracorporeal circuit were studied and compared to a control. The Baxter Bentley OxySat, Oximetrix Accusat, and Radiometer ABL4 blood gas monitor were compared to a control, the IL 282 Co-Oximeter. Fifty-one sample points were obtained during all phases of cardiopulmonary bypass with results as follows: table: see text. The Accusat was found to be a statistically more accurate means of monitoring hemoglobin oxygen saturations during cardiopulmonary bypass than the ABL4 and the OxySat. All devices had significant correlation with the control and with each other.

An outbreak of cholera in Australia due to food served in flight on an international aircraft.

An outbreak of cholera occurred in November 1972 among passengers on an aircraft that had flown from London to Sydney. The infection was confined to economy-class passengers and the available evidence indicates that it was due to a dish of hors d'oeuvres served on the aircraft between Bahrain and Singapore. Although one person died, the infection was generally mild, and almost half of those infected were symptomless. There was a significant difference between the immunization status of persons with clinical illness and the immunization status of other passengers. Current cholera immunization appeared to play a significant role in preventing symptoms of the disease, but it did not prevent a person becoming a carrier of the organism.

The effect of two methods of cooking and cooling on Clostridium welchii and other bacteria in meat.

A comparison was made of beef cooked in conventional and moist air (Rapidaire) ovens. In both large (ca. 4.5 kg.) and small (ca. 2.7 kg.) joints, spores of Clostridium welchii survived after cooking but vegetative cells, Escherichia coli, and Staphylococcus aureus, did not, regardless of the type of oven used.Cooling at room temperature after cooking permitted growth of Cl. welchii. Although some multiplication also occurred in the centre of large roasts cooled under refrigeration, the viable counts were considered too low to constitute a potential health risk.