The AustralAsian Journal of Cardiac and Thoracic Surgery最新文献

The abnormal physiology of cardiopulmonary bypass includes haemodilution, hypothermia, interstitial fluid accumulation, complement activation and depression of immune mechanisms. These factors have many interactions and relationships. Haemodilution ameliorates the adverse effects of hypothermia and the heart-lung machine on organ blood flow, oxygen delivery and renal function. Complement activation produces vasoconstriction, capillary leakage and whole-body inflammatory reaction. Interstitial fluid accumulation is partly due to dilution of plasma oncotic pressure during hemodilution. Fluid accumulation during cardiopulmonary bypass is related to duration on cardiopulmonary bypass, the underlying cardiac disease, patient's age, female sex, obesity, aorto-iliac-femoral occlusive disease, and low ejection fraction. Hypothermia of varying degrees is used during cardiopulmonary bypass. The principal advantage of hypothermia is the lowering of total body oxygen demand. The period of rewarming following hypothermia is a time of accelerated complement activation. For routine coronary bypass operations, perfusion at lower temperatures may be associated with greater morbidity. All components of immune function are depressed following cardiopulmonary bvypass. Immune globulins are diluted, denatured and consumed during cardiopulmonary bypass. Polymorphonuclear leukocytes decrease in number and in function. The function of lymphocyte subgroups is depressed following cardiopulmonary bypass. The reticuloendothelial system undergoes blockage during bypass. The ability of the reticuloendothelial system to ingest circulating bacteria and other microparticles is diminished following cardiopulmonary bypass. Specific protocols for conducting cardiopulmonary bypass to preserve organ function have recently been developed. These specific protocols are designed to decrease the incidence and severity of renal failure and neurologic dysfunction.

Most types of respiratory failure in the newborn are reversible, but supportive treatment can damage the lungs and airways. In the last decade prolonged extracorporeal membrane oxygenation (ECMO) has become an accepted technique, particularly in the neonatal group. We have placed 46 patients (26 neonates, 20 children) on ECMO for respiratory or cardiac support. The major indications in neonatal patients were congenital diaphragmatic hernia, persistent foetal circulation and meconium aspiration. The major indications in children were bacterial and viral pneumonias and systemic sepsis with respiratory failure. The hospital survival was 65% in the neonatal group and 40% in the paediatric group. The majority of neonatal deaths occurred in the group with congenital diaphragmatic hernia. In the other neonatal patients hospital survival was 74%. Carotid and jugular cannulation was the preferred technique, with vascular repair at the time of decannulation. Only one neonate and one child who have survived have a neurological or developmental deficit. We conclude that ECMO is most suitable for neonates with reversible lung disease, and congenital diaphragmatic hernia remains the major cause of death, due to pulmonary hypoplasia. The poorer results in children reflect the greater incidence of destructive and irreversible lung disease in this group, with associated systemic sepsis, multiorgan failure and coagulopathy from the primary disease.

A simplified technique for introducing antegrade and subsequently retrograde cardioplegia during cardiac surgery is described. The circuit is less expensive but just as efficient as the standard delivery system for antegrade transaortic and retrograde transatrial cardioplegia.