Increase Oxygen Transport Capacity
In a recent multicentre trial 2,007 patients undergoing non-emergency cardiac surgery were randomly assigned to a restrictive (haemoglobin <75 g/l) or a liberal transfusion threshold (haemoglobin <90 g/l). No differences concerning morbidity or health costs between the two groups were shown but deaths increased in the restrictive-threshold group (4.2 % vs 2.6 %, P=0.045).94 In patients with septic shock, no differences in outcome were shown between patients receiving blood transfusion at a threshold of 70 g/l compared to a threshold of 90 g/l.95 Strikingly, 50 % fewer units of blood were used in the low-threshold group. Importantly, blood transfusions have been associated with an increased morbidity94,96 and mortality97,98 after cardiac surgery. According to local policy in Zurich, a restrictive transfusion strategy is followed. After targeting a haematocrit of 27 % in the acute shock phase, a haematocrit level as low as 21 % is tolerated if no signs of oxygen misbalance (e.g. arrhythmias, ST segment changes, low SvO2, rising lactate levels, worsening metabolic acidosis) or obvious blood loss are evident. The indication for transfusion should be verified individually and for every single blood unit in the authors’ opinion.
Consider Extracorporeal Life Support
If shock does not resolve with pharmacological support, arterio- venous extracorporeal life support (ECLS) should be considered. ECLS can be used as a bridge to decision, bridge to bridge or bridge to transplantation.99 The possibility of rapid insertion of peripheral veno-arterial cannulas in shock is one of the advantages of ECLS.
This can even be done in conscious patients, thereby avoiding the risks of sedation, intubation and mechanical ventilation.100 Intra- aortic balloon pump (IABP) increases diastolic arterial pressure as well as coronary perfusion and decreases afterload, systolic blood pressure and myocardial oxygen consumption. However, no benefit on 30-day mortality could be demonstrated for the use of IABP in cardiogenic shock.101,102 In smaller trials, a benefit was found for IABP in patients with acute ischaemic mitral regurgitation and other mechanical complications of myocardial ischemia.103,104 Hence, IABP can only be recommended in selected patients with mechanical complications as bridge to cardiac surgery. The IABP is also inserted postoperatively in patients with decompensated left-sided heart failure of primarily ischaemic aetiology (with or without secondary mitral regurgitation) as bridge to recovery, when increasing doses of inotropes are necessary to stabilise the patient.”
Fight Bacterial Infections
Surgical infection control (e.g. sternal wound infection) and empiric antibiotic therapy are most important in the fight against bacterial infections. In septic shock, the early administration of intravenous antibiotics improves outcome, as mortality increased 7.6 % for each hour antibiotics were delayed after the onset of hypotension.9 According to the Surviving Sepsis Campaign guidelines, empiric antibiotics should be administered within the first hour after sepsis recognition.5,105 Cultures of blood and other specimens should be obtained before the first administration of antibiotics.5
Consider Anti-inflammatory Strategies
In patients after cardiac surgery, an inflammatory response is initiated by the surgical trauma itself (Figure 1), contact activation of the inflammatory cascade by the bypass circuit and ischaemia- reperfusion injury.106–109 Conflicting studies exist on the use of steroids after cardiac surgery, some of them reporting a decrease in catecholamine support and a shorter ICU stay.110,111 Supplementation of 50 mg hydrocortisone iv qid is a place to start when distributive shock persists and the noradrenaline requirement is > 0.3 mcg/kg/min iv.