Do cardiac children need more red blood cell transfusions than other critically ill children?

Abstract

Anaemia is associated with a higher risk of mortality in cardiac adults [1,2] and children [3]. Only a red blood cell (RBC) transfusion can rapidly increase a low haemoglobin (Hb) concentration. However, there is no such thing as a perfectly safe RBC transfusion: both transfusion-transmitted infections and non-infectious serious hazards of transfusion (NISHOT) can occur [4]. RBC transfusions are associated with a higher mortality rate in cardiac adults [5] and with more morbidity in cardiac children [6][7][8][9]. An association between RBC transfusions and worse outcomes does not mean that there is a cause-effect relationship; it means only that such a cause-effect relationship is possible, and it questions the assertion that RBC transfusions are actually more useful than harmful in patients with cardiovascular disease.In clinical practice, cardiac patients receive more RBC transfusions than other critically ill children [9][10][11]. The question is what prompts physicians to prescribe an RBC transfusion. According to a self-administered survey, determinants in cardiac children include Hb level, patient's stability, active bleeding, inadequate O 2 delivery (low ScvO 2 , high lactate level, low SaO 2 /FiO 2 ratio) and low blood pressure [10]. However, the Hb level remains the most important determinant of RBC transfusion [10,11]. Therefore, it makes sense to ask ourselves the following questions: in cardiac children, how much anaemia can we tolerate and when do the benefits of RBC transfusions overcome their harms?RBC transfusions are given during the perioperative care of paediatric cardiac surgery in the operating room and in the intensive care unit (ICU). While cardiac surgery accounts for only 5 % of anaesthesia episodes, it represents 58 % of perioperative RBC use and 24 % of total hospital RBC use [12]. The lowest Hb level below which an RBC transfusion must be given during a cardiopulmonary bypass (CPB) is not well characterised. Jonas et al. [13] reported that infants randomised at CPB onset to an haematocrit of 20 % (Hb level: about 7 g/dl) had worse 1-year Bayley psychomotor development scores than those allocated to 30 % (10 g/dl); this suggests that the Hb level should be maintained over 7 during a CPB, but it does not tell us what is the best and safest threshold Hb level for transfusion over 7 g/dl.The uncertainty about the threshold Hb level with the best risk/benefits ratio also arises in the ICU after surgery. Most cardiac children (range: 46-79 %) receive at least one RBC transfusion during their ICU stay after a cardiac surgery [15,16]. However, recent data suggest that a restrictive transfusion strategy might be as safe, if not safer than a liberal transfusion strategy. A subgroup analysis that focussed on 125 cardiac children enrolled in the Transfusion Requirements in Pediatric ICU (TRIPI-CU) randomised clinical trial reported that a threshold Hb level of 7 was as safe as 9.5 g/dl in stable non-cyanotic cardiac infants [14].In this issue, de Gast-Bakker et al.[15] published a randomised clin...

Year in review in Intensive Care Medicine 2013: III. Sepsis, infections, respiratory diseases, pediatrics

“…In the restrictive group less blood was used, costs were lower, and, most importantly, the length of hospital stay was reduced [restrictive median 8 (IQR 7-11) vs. liberal 9 (IQR 7-14) days, p = 0.047] [43]. The accompanying editorial reminds us once again of the central importance of primum non nocere [44]. This theme recurred throughout the year.…”

“…Of the respondents, who represented 611 departments in 70 countries, 99 % reported using aerosol therapy during mechanical ventilation (including noninvasive), 43 % exclusively used nebulizers and 55 % also used metered dose inhalers. Nebulization relied on jet, ultrasonic, and vibrating mesh nebulizers (55,44, and 14 % of respondents, respectively). During nebulization, ventilator settings were never changed by 77 % of respondents, 65 % reported placing a filter on the expiratory limb, and of these 28 % never changed it.…”