Prone and ECMO - a contradiction per se?

Acute respiratory distress syndrome (ARDS) still represents a serious problem in clinical routine and is associated with a high mortality. Several concepts are known for special treatment, but, in some instances, the application of an extracorporeal membrane oxygenation (ECMO) is necessary for both the improvement of oxygenation and the elimination of carbon dioxide (CO(2)). One basic aspect in lung protective ventilation in this context is alveolar recruitment, which can be achieved by different approaches, such as "the open lung concept", according to Lachmann, or by additional kinetic therapy. The most exposed feature of this entity is 'prone', which may be quite challenging in patients requiring extracorporeal support or organ replacement therapy under ongoing critical illness. We report two outstanding cases of prone under conditions of a veno-venous ECMO therapy which improved significantly under this position. Furthermore, we reflect critically possible risk factors and adverse events of such procedures and afford a current view from the literature.

Beating heart valve surgery using stentless xenografts as a surgical alternative for patients with end-stage renal failure

Patients suffering from end-stage renal disease are an inhomogeneous high-risk group with a substantial perioperative mortality and morbidity when undergoing cardiac surgical procedures[1-3]. Myocardial ischemia, reperfusion injury and myocardial edema are a few of the deleterious consequences of the traditional use of cardioplegic arrest when performing valve surgery,irrespective of the type of cardioplegia used [4-7]. Novel operative techniques are required to reduce these induced perioperative risks. Clinical studies in the past have demonstrated the efficacy of beating heart valve surgery in the high-risk patient using retrograde, antegrade or combined coronary perfusion with warm oxygenated blood [8, 9]. We chose to combine the superior hemodynamic profile of stentless xenografts with the concept of performing valve replacement on the empty beating heart with continuous antegrade application of oxygenated blood in 2 chronic hemodialysis patients.

Cardiopulmonary bypass copolymer surface modification reduces neither blood loss nor transfusions in coronary artery surgery

OBJECTIVE

Surface-modifying additives (SMA) have been suggested for improving cardiopulmonary bypass (CPB) circuit biocompatibility, potentially minimizing inflammatory complications and bleeding associated with CPB. The purpose of this prospective, randomized clinical study was to compare a novel copolymer surface-modified CPB circuit (SMARXT; COBE Cardiovascular) against the unmodified circuit.

METHODS

We randomized 122 patients with isolated coronary artery disease subjected to first-time surgery on CPB into either the SMA (n = 62) or the control group (n = 60). Exclusion criteria included renal insufficiency, liver disease, coagulopathy, anticoagulation therapy < 6 days preop, carotid artery stenosis > 70 %, and a history of stroke. We collected perioperative clinical data including drainage blood loss, transfusion requirements, duration of mechanical ventilation, and ICU stay. Platelet function was determined pre- and post-CPB.

RESULTS

SMA patients received 3.2 +/- 0.9 (SD) grafts during 48 +/- 16 min of aortic cross clamp and 91 +/- 30 min CPB (Control: 3.0 +/- 0.9 grafts; p = 0.33, 46 +/- 14 min AXC; p = 0.36, and 84 +/- 23 min CPB; p = 0.14). In the SMA group, 23 patients (37 %) received red blood-cell transfusions, 9 patients (15 %) fresh frozen plasma, and 3 patients (5 %) received platelets (control: n = 27 [46 %], p = 0.44; n = 10 [17 %], p = 0.91; and n=4 [7 %], p = 0.71, respectively). Platelet count on CPB fell to the same level in both groups. In SMA patients, platelet function decreased from 94.2 +/- 24.9 % pre-CPB to 79.5 +/- 32.8 % post-CPB (p = 0.043) (control: from 87.7 +/- 25.6 % to 69.4 +/- 34.7 %; p = 0.001). Postoperative drainage blood loss, mechanical ventilation duration, and ICU stay were similar in both groups (p > 0.3). One patient of the control group was excluded due to surgical bleeding, and one SMA patient died.

CONCLUSIONS

Our results show that the surface-modified CPB circuit decreased neither blood loss nor transfusions despite slightly better platelet function preservation compared to the unmodified circuit. This type of CPB circuit surface modification does not appear to improve clinical outcome in low-risk coronary artery surgery patients.