Reducing the risk of major elective non-cardiac surgery: is there a role for levosimendan in the preoperative optimization of cardiac function?

Patients with heart failure undergoing non-cardiac surgery still have an unacceptably high morbidity and mortality. Compromised myocardial physiologic reserves in combination with extensive surgery and anesthesia appear to play a crucial role in determining high perioperative morbidity and mortality. Nevertheless, several other mechanisms and pathways such as metabolic factors, ischemia-reperfusion conditions, neurohormonal activation, inflammation and oxidative stress contribute to the adverse outcome. Several cardiovascular drugs have been investigated with the attempt to reduce the incidence of cardiovascular adverse events after major non-cardiac surgery. In the last years, increasing attention has been paid to the use of levosimendan in the perioperative period of patients undergoing cardiac surgery. As an inodilator, levosimendan - at low energy expenditure - may improve perioperative cardiac performance of heart failure patients by optimizing ventriculo-arterial coupling, rather than by increasing myocardial contractility itself. By its vasodilating properties, levosimendan may also improve systemic and regional blood flow. In addition to these hemodynamic properties, non hemodynamic effects of levosimendan may further improve microcirculation and organ function. At the cellular level in the heart, kidney, lung, liver as well as the gut, levosimendan exerts protective preconditioning effects secondary to activation of adenosine triphosphate (ATP)-sensitive potassium channels. Taking into account these multiple but complementary mechanisms, levosimendan appears to be a suitable agent for preoperative optimization of cardiac functions in heart failure patients undergoing major elective surgery. Nevertheless, large-scale trials are needed before final conclusions can be drawn on the use of levosimendan in this indication.

Exogenous adrenomedullin prevents and reverses hypodynamic circulation and pulmonary hypertension in ovine endotoxaemia.

BACKGROUND: Hypodynamic septic shock is associated with a poor prognosis. The present randomized-controlled laboratory experiment was designed to test the hypothesis that the vasodilatory peptide hormone adrenomedullin (ADM) is a useful agent to prevent and reverse the development of hypodynamic circulation in ovine endotoxaemia. METHODS: Twenty-four healthy ewes were chronically instrumented for haemodynamic monitoring and randomly allocated to either the control, treatment, or prophylaxis group (n = 8 each). After a baseline (BL) measurement in the healthy state, all sheep were subjected to a continuous endotoxin infusion started at 10 ng kg(-1) min(-1) and doubled every hour six times. After 4 h of endotoxin challenge, the treatment group received ADM (50 ng kg(-1) min(-1)) for the remaining 3 h of the experiment. The prophylaxis group received a simultaneous infusion of endotoxin and ADM (50 ng kg(-1) min(-1)) from the beginning to the end of the 7 h intervention period. RESULTS: In the control and treatment groups, the ewes exhibited a hypodynamic circulation at 4 h (>20% reduction in cardiac index, both P < 0.01 vs BL). Endotoxin also increased mean pulmonary arterial pressure (MPAP) and arterial lactate concentrations. Prophylactic infusion of ADM prevented the occurrence of pulmonary hypertension and hypodynamic circulation and thereby blunted the increase in arterial lactate concentrations. In the treatment group, ADM administration increased CI (P < 0.001) and reduced both MPAP (P = 0.023) and arterial lactate concentrations (P < 0.001 each at 7 h) when compared with the control group. CONCLUSIONS: This study demonstrates that exogenous ADM prevents and reverses hypodynamic circulation, attenuates pulmonary hypertension, and limits lactic acidosis in ovine endotoxaemia.

Processing of stored packed red blood cells using autotransfusion devices decreases potassium and microaggregates: a prospective, randomized, single-blinded in vitro study.

The aim of the study was to compare the potential of autotransfusion devices to reduce non-infectious complications related to transfusion of long-stored packed red blood cells (PRBC; n= 57), such as changes in electrolytes, blood cells and the load of free microaggregates. Following a baseline measurement, a blood pool of three PRBC was divided into three equal volumes and washed with either the Haemonetics Cell Saver (HCS) or the continuous autotransfusion system (C.A.T.S), using the quality (CATS(quality)) and emergency (CATS(emergency)) mode. After the washing procedure, measurements for electrolytes, blood cells and free microaggregates were repeated (n= 19 each). Compared with baseline, the investigated autotransfusion devices reduced the median load of potassium (baseline: 52 mEq L(-1); HCS: 4 mEq L(-1); CATS(quality): 4 mEq L(-1); CATS(emergency): 17 mEq L(-1); each P < 0.001), restored a physiologic electrolyte balance and significantly decreased the load of leucocytes, glucose and protein. Whereas the quantity of microaggregates was not reduced by HCS, CATS(emergency) decreased the load of cell fragments below 7.8 microm (P < 0.05 vs. baseline). Using CATS(quality) decreased the load of cell fragments not only to a diameter below 7.8 microm (P < 0.001 vs. baseline) but also of microaggregates between 7.8 and 17.6 microm (P < 0.05 vs. baseline). In situations where long-stored PRBC have to be transfused, the procedure described here may be feasible to reduce clinically relevant side effects, i.e. hyperkalaemia and microvascular obstruction secondary to free cell fragments. This approach could be especially useful in patients undergoing massive transfusion and/or suffering from renal failure.