ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
-
The anaerobic threshold represents an objective measure of functional capacity and is useful in assessment of pulmonary and cardiovascular dysfunction. This study determined the anaerobic threshold in total artificial heart animals and evaluated the performance of the total artificial heart system. Five animals with total artificial hearts were put under incremental exercise testing after exercise training. ⋯ The value of the anaerobic threshold in total artificial heart animals implies that the performance capacity of a total artificial heart is not sufficient to meet the oxygen requirements of vigorously exercising skeletal muscle. The protocol does not allow for driving parameter changes during exercise, and this situation, combined with the manual mode of the control system used, was inadequate to allow the total artificial heart animals to exercise more vigorously. Using an automatic control mode might be helpful, as well as considering the relationship between indices of oxygen metabolism, such as oxygen delivery, oxygen consumption, and oxygen extraction rate, in the control algorithms in total artificial heart control systems.
-
The authors induced endotoxic shock in an animal model and attempted to treat this state by direct hemoperfusion over a modified anion sorbent column. It has been shown that the reversal of septic shock correlates with the efficiency of extracorporeal endotoxin removal. In this experiment, there were five control animals (sham) and five test animals (hemoperfusion over sorbent column). ⋯ The control dogs never recovered from shock or metabolic acidosis, but the test animals were at their initial values for these parameters by 6 hr. The endotoxin levels measured at 6 hr were higher in the control group (265 +/- 88 ng/ml) as compared with the test group (7.0 +/- 6.2 ng/ml). Direct hemoperfusion over a modified sorbent column effectively removed endotoxin and reversed the course of fatal septic shock.
-
Comparative Study
Monitoring of blood gases during prolonged experimental cardiopulmonary bypass and their relationship to brain pH, PO2, and PCO2.
Eight adult goats under went 5 hr of normothermic cardiopulmonary bypass (CPB) with pulsatile (n = 3) and nonpulsatile flow (n = 5). PaCO2 was maintained at 30-40 mmHg and blood flow rate at 50 ml/min/kg. Brain tissue pH, PO2, and PCO2, arterial and venous blood gases, and other systemic variables were monitored. ⋯ Brain tissue PO2 closely followed the values of PvO2, suggesting that PvO2 can be an indicator of brain tissue PO2 during normothermic CPB and must be monitored during the procedure. Brain tissue acidosis is evidently related to neurologic dysfunction after CPB, and must be addressed. Replacement of the priming solution with whole blood or artificial blood, reduction of the priming volume, and application of vigorous pulsatile flow appear feasible interventions to mitigate brain tissue acidosis during CPB.
-
The intravascular oxygenator and carbon dioxide removal device (IVOX; CardioPulmonics, Salt Lake City, UT) has been shown to perform 30% of the gas exchange in animals and patients with acute respiratory failure. Among the factors that limit gas exchange is the mass transfer resistance in the blood phase. To determine if a reduction in mass transfer resistance by mixing venous blood can enhance the O2 transfer and CO2 removal by IVOX, a right atrium-pulmonary artery venovenous bypass circuit was used in sheep to model the adult vena cava. ⋯ It is concluded that reduction in the mass transfer resistance by blood mixing improves gas exchange. Because O2 is more diffusion limited, it is more dependent upon mixing of blood for gas exchange than CO2. More design improvements to incorporate active mixing may further enhance the gas exchange performance of IVOX.
-
Case Reports
Use of a 12 French double-lumen catheter in a newborn supported with extracorporeal membrane oxygenation.
We present the first report of clinical experience with a 12 French double-lumen cannula in a newborn supported with venovenous extracorporeal membrane oxygenation. This cannula was used because the internal jugular vein could not accommodate a 14F double-lumen catheter. ⋯ The infant was successfully weaned from extracorporeal membrane oxygenation and discharged home at 35 days of age. We suggest that this 12F catheter may be beneficial and deserves further evaluation.