Permissive hypercapnia is a well-accepted ventilator strategy for the management of acute respiratory distress syndrome as well as other causes of respiratory failure, such as the respiratory distress syndrome seen in premature infants. Multiple studies have demonstrated that both myocardial contractility and systemic vascular resistance (SVR) decrease with hypercapnic acidosis, the ultimate effect being that cardiac function is maintained or even augmented. The effects of hypercapnic acidosis on cardiac function in the preterm infant have not been elucidated. In a prospective observational study, published in the May issue of The Journal of Pediatrics, the authors analyzed paired blood gasses and echocardiograms from 29 hemodynamically stable preterm infants at 30 weeks gestation
Samples were taken within the first two weeks of life, either during the transitional period (days 1-3) or post-transitional period (days 4-14). In all, there were 103 paired blood gasses and echocardiograms from 21 subjects in the transitional period and 44 paired studies from 15 subjects in the post-transitional period. During the transitional period, pH and PaCO2 had no effect on any of the hemodynamic measures, including shortening fraction, stress-velocity index, or SVR. However, during the post-transitional period, the infants’ hemodynamics resembled those seen in adult patients. The results of the study demonstrated differences in the way the older infants responded to acidosis and hypercapnia. Read the full Concise Critical Appraisal.
Although anemia may cause an increase in morbidity and mortality rates in critically ill pediatric patients, transfusion of packed red blood cells (pRBCs) carries significant risks, which have also been demonstrated in pediatric cardiac surgery patients. However, studies related to these risks have had problems with confounding and the use of pRBCs that were not leukoreduced. Kneyber et al address these concerns in their study testing whether transfusion of leukocyte-depleted pRBCs within the first 48 hours after cardiac surgery would be independently associated with prolonged duration of mechanical ventilation. Results were published in the March 2013 issue of Pediatric Critical Care Medicine.
Kneyber and colleagues retrospectively analyzed data from 335 children between the ages of 0 months to 18 years who underwent cardiac surgery between 2007 and 2010. Of these subjects, 111 were transfused, 86 of them within the first 48 hours of admission to the pediatric intensive care unit. The author then compared the outcomes of these 86 patients to those of the 249 who were not transfused within 48 hours. Patients who received pRBCs within the first 48 hours had a longer duration of ventilation and inotropic support, longer ICU stay, and a higher rate of ventilator-associated pneumonia. However, after adjusting for the severity of illness, the transfusion of pRBCs within the first 48 hours remained independently associated with only the prolonged duration of mechanical ventilation. This study provides more evidence against arbitrary decisions to transfuse blood products. Prospective studies are necessary to determine which transfusion triggers will provide more benefit than cost. Read the full Concise Critical Appraisal.