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Peri-operative acute renal failure requiring renal replacement therapy is common (5–30%) after cardiac surgery and associated with a mortality of ∼50%. Pre-operative renal impairment seems to be the most important risk factor for frank postoperative renal failure. To help evaluate the risk factors, we conducted a prospective observational trial of 1574 consecutive patients with normal pre-operative renal function (creatinine < 110 μmol.l−1). Renal failure was defined as the need for renal replacement therapy. After univariate analysis of previously described risk factors, those who differed significantly between patients with or without renal failure were enrolled into a multivariate classification and regression tree (CART) statistical model that identifies the most ‘predictive’ risk factors and creates a ranked list of these. In patients with pre-operatively normal renal function, a serum level of lactate > 1.1 mmol.l−1 in the first 24 h after the operation was the strongest predictor for the development of renal failure. [ABSTRACT FROM AUTHOR]

The Infostations system, small and separated islands of coverage, provides intermittent but very high speed data rates. A new communication model is needed to carry this kind of architecture. Mainly, the discontinuous coverage affects the way data are exchanged between mobile terminals and the network. Moreover, the short time the mobile terminal spends in the coverage area has a direct impact on the network performance. Thus, it is essential to avoid bandwidth wasting due to the overall delay by performing mobility prediction. A new mobility prediction protocol called the Distributed Neighbor Discovery Protocol (DNDP) is proposed. DNDP handles a neighbor graph table that dynamically configures itself according to the terminals' mobility. The simulation shows that the terminals service continuity is significantly improved thanks to DNDP. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Arterial hypotension with vasopressor dependence is a major problem after cardiac surgery. We evaluated the early postoperative course of 1558 consecutive patients scheduled for cardiac surgery, and compared the outcome of patients with and without vasopressor dependence (defined as the need for > 0.1 μg.kg−1.h−1 noradrenaline for > 3 h in the face of normovolaemia). Vasopressor dependence was diagnosed in 424 patients (27%) and was associated with a higher incidence of postoperative renal failure (67 (15.7%) vs 7 (0.6%), respectively; p < 0.0001), a longer duration of ventilation (median IQR [range]) 14 (8–26 [6–39]) h vs 8 (5–11 [4–32]) h; p < 0.0001), a greater need for red cell transfusion (3 (1–5 [0–10]) units vs 1 (0–2 [0–4]) units; p < 0.001) and a longer length of stay in the ICU (4 (2–6 [2–9] days) vs 2 (1–3 [1–6] days; p < 0.001). Vasopressor dependence could be predicted from a combination of factors, including pre-operative ejection fraction < 37%, cardiopulmonary bypass lasting > 94 min, and postoperative interleukin-6 > 837 pg.ml−1. [ABSTRACT FROM AUTHOR]

We report a 56-year-old male patient developing hypoxemia after surgical replacement of infected valves of a left ventricular assist device (LVAD, Novacor) which had supported him during the previous 15 months. Contrast transesophageal echocardiography (TEE) revealed an atrial septal defect with intermittent right-to-left shunt across a patent foramen ovale. We postulate that the shunt detected in this patient occurred as a consequence of reduced pulmonary vascular compliance due to positive end-expiratory pressure (PEEP) and an increase of mean intrathoracic pressure. Furthermore, we hypothesize that synchronized LVAD operation exacerbates any potential right-to-left shunt due to the profound left ventricular unloading which occurs during LVAD support. In this first report of a right-to-left shunt from a previously unrecognized patent foramen ovale in a Novacor patient, the subsequent transient hypoxemia could be managed by avoiding PEEP of more than 3 mmHg, and mean airway pressure of more than 11 mmHg and by careful volume replacement in order to prevent the pump from completely emptying the left ventricle (LV) and the left atrium (LA). Thus, prior to every LVAD implantation a transesophageal contrast echocardiography with Valsalva maneuver should be performed to identify intracardiac right-to-left shunt. [ABSTRACT FROM AUTHOR]

A response by F. Weis and A. Beiras-Fernandez to a letter to the editor about their article "Risk and outcome analysis of renal replacement therapies in patients after cardiac surgery with pre-operatively normal renal function" in the 2009 issue is presented.

Replies to a commentary on a case report concerning temporary hypoxemia from right-to-left shunting in a patient during support with a left ventricular assist device and a patent foramen ovale previously published in the periodical 'Acta Anaesthesiological Scandinavia' in 2000. Shunting triggered by the device; Causes of the closure of the patent foramen ovale.