Harris P. Baden

Dexamethasone reduces the inflammatory response to cardiopulmonary bypass in children

BACKGROUND A randomized, prospective, double-blind study of 29 children was performed to evaluate the hypothesis that dexamethasone administration prior to cardiopulmonary bypass would decrease the inflammatory mediator release and improve the postoperative clinical course. METHODS Fifteen children received dexamethasone (1 mg/kg intravenously) and 14 (controls) received saline solution 1 hour prior to CPB. Serial blood analyses for interleukin-6, tumor necrosis factor-alpha, complement component C3a, and absolute neutrophil count were performed. Postoperative variables evaluated included temperature, supplemental fluids, alveolar-arterial oxygen gradient, and days of mechanical ventilation. RESULTS Dexamethasone caused an eightfold decrease in interleukin-6 levels and a greater than threefold decrease in tumor necrosis factor-alpha levels after CPB (p < 0.05). Complement component C3a and absolute neutrophil count were not affected by dexamethasone. The mean rectal temperature for the first 24 hours postoperatively was significantly lower in the group given dexamethasone than in the controls (37.2 degrees +/- 0.4 degrees C versus 37.7 degrees +/- 4 degrees C; p = 0.007). Dexamethasone-treated patients required less supplemental fluid during the first 48 hours (22 +/- 28 mL/kg versus 47 +/- 34 mL/kg; p = 0.04). Compared with controls, dexamethasone-treated children had significantly lower alveolar-arterial oxygen gradients during the first 24 hours (144 +/- 108 mm Hg versus 214 +/- 118 mm Hg; p = 0.02) and required less mechanical ventilation (median duration, 3 days versus 5 days; p = 0.02). CONCLUSIONS Dexamethasone administration prior to CPB in children leads to a reduction in the postbypass inflammatory response as assessed by cytokine levels and clinical course.

Noninvasive positive-pressure ventilation in children with lower airway obstruction

Study Objectives: Mechanical ventilation of patients with severe lower airway obstruction presents significant risks; therefore, avoiding the intubation in these patients has been a principal goal of clinical management. Noninvasive positive-pressure ventilation has been shown to be effective in treating adults with chronic obstructive pulmonary disease, but its use has not been studied prospectively in children with acute obstructive lower airways disease. The objective of this study was to determine whether noninvasive mask ventilation improved respiratory function in children with asthma and other obstructive lower airways diseases. Study Design: A prospective, randomized, crossover study. Patients: A total of 20 children admitted to the pediatric intensive care unit with acute lower airway obstruction. Methods: Children were randomized to receive either 2 hrs of non-invasive ventilation followed by crossover to 2 hrs of standard therapy or 2 hrs of standard therapy followed by 2 hrs of noninvasive ventilation. Results: Using a Clinical Asthma Score, we found that noninvasive ventilation decreased signs of work of breathing such as respiratory rate, accessory muscle use, and dyspnea as compared with standard therapy. There was no serious morbidity associated with noninvasive ventilation. Conclusions: We conclude that noninvasive ventilation can be an effective treatment for children with acute lower airway obstruction.

Dexamethasone reduces postoperative troponin levels in children undergoing cardiopulmonary bypass.

OBJECTIVE We previously demonstrated that dexamethasone treatment before cardiopulmonary bypass in children reduces the postoperative systemic inflammatory response. The purpose of this study was to test the hypothesis that dexamethasone administration before cardiopulmonary bypass in children correlates with a lesser degree of myocardial injury as measured by a decrease in cardiac troponin I release. DESIGN A prospective, randomized, double-blind study. SETTING The cardiac surgery operating room and intensive care unit of a pediatric referral hospital. SUBJECTS Twenty-eight patients who underwent open-heart surgery for congenital heart defects. INTERVENTIONS Patients received either placebo (group I, n = 13) or dexamethasone, 1 mg/kg iv (group II, n = 15), 1 hr before initiation of cardiopulmonary bypass. Plasma cardiac troponin I samples were obtained at three time points: immediately before study agent (sample 1), 10 mins after protamine sulfate administration after cardiopulmonary bypass (sample 2), and 24 hrs postoperatively (sample 3). MEASUREMENTS AND MAIN RESULTS Mean cardiac troponin I levels (+/-sd) were significantly lower at sample time 3 in group II (dexamethasone; 33.4 +/- 20.0 ng/mL) vs. group I (control; 86.9 +/- 81.1) (p =.04). CONCLUSION Dexamethasone administration before cardiopulmonary bypass in children resulted in a significant decrease in cardiac troponin I levels at 24 hrs postoperatively. We postulate that this may represent a decrease in myocardial injury, and, thus, a possible cardioprotective effect produced by dexamethasone.

High-frequency oscillatory ventilation with partial liquid ventilation in a model of acute respiratory failure.

OBJECTIVE To determine whether there is an improvement in oxygenation when partial liquid ventilation and high-frequency oscillatory ventilation are combined in the treatment of acute lung injury, compared with high-frequency oscillatory ventilation alone. DESIGN Controlled animal trial. SETTING Research laboratory in a university setting. SUBJECTS Ten 3-kg piglets. INTERVENTIONS Anesthetized piglets underwent high-frequency oscillatory ventilation, with mean airway pressure of 20 cm H2O, before induction of acute lung injury with repeated saline lavage. When PaO2 values were < 100 torr (< 13.3 kPa), five animals were randomized to receive escalating doses (3, 15, and 30 mL/kg) of perflubron at 60-min intervals. The other five animals remained on high-frequency oscillatory ventilation only. Sham dosing was performed at 60-min intervals in these animals. Arterial blood gases were obtained in both groups at baseline, after injury, and after perflubron and sham doses. MEASUREMENTS AND MAIN RESULTS Statistically significant improvements in oxygenation were demonstrated in animals that received 3 mL/kg of perflubron with high-frequency oscillatory ventilation compared with animals receiving high-frequency oscillatory ventilation alone (253 +/- 161 vs. 90 +/- 30 torr [33.65 +/- 21.46 vs. 12.0 +/- 4.0 kPa], p < .05). Improvements in oxygenation with additional administration of perflubron were not greater than the improvements seen in the high-frequency oscillatory ventilation-only group. PaCO2 and pH were similar in both groups at all times. No hemodynamic compromise occurred in either group of animals. CONCLUSIONS The combination of low-dose perflubron with high-frequency oscillatory ventilation leads to more rapid improvement in arterial oxygenation than high-frequency oscillatory ventilation alone, in a piglet model of acute lung injury. Although the group receiving high-frequency oscillatory ventilation alone eventually achieved PaO2 values that were equivalent to the group receiving high-frequency ventilation and perflubron, the combination of perflubron with high-frequency oscillatory ventilation may permit effective oxygenation and ventilation at lower mean airway pressures by facilitating alveolar expansion and decreasing intrapulmonary shunt.

Myocardial injury in children with respiratory syncytial virus infection.

Objective Respiratory syncytial virus (RSV) infection is associated with a number of extrapulmonary manifestations, including a sepsis-like syndrome characterized by any combination of hypothermia, fever, apnea, hypovolemia, and myocardial dysfunction. We hypothesized that RSV can have a direct injurious effect on the myocardium of infants and children that can be detected by the presence of cardiac troponin I (cTnI), a highly sensitive and specific marker of myocardial injury, in the blood of patients infected with the virus. Design Serial cTnI measurements were obtained from patients admitted with documented RSV infection to the pediatric intensive care unit (PICU). Participants Data were collected and analyzed from 22 RSV infected patients and 11 control patients. Results Elevated levels of cTnI were detected in 54.5% (12/22) of the study population during their PICU admission. The average cTnI level was significantly higher in the RSV infected group than in controls. There was a significant association between the presence of a positive troponin assay and the occurrence of a cardiovascular event, the need for inotropic support, and the requirement of mechanical ventilation. Patients who required inotropic support had a significantly higher cTnI level than the rest of the study population. Conclusion A large percentage of children admitted to the PICU with RSV infection have myocardial damage as detected by the use of commercially available troponin assays. Additionally, in a portion of these patients, this damage is clinically significant, leading to cardiovascular instability and the need for inotropic support.

Trends in pediatric organ donation after cardiac death.

OBJECTIVE. Organ donation after cardiac death is viewed as one way of partially closing the current gap between organ supply and demand. There are no published guidelines for organ donation after cardiac death specific to the pediatric population. The objective of this study was to examine the cumulative pediatric donation-after-cardiac-death experience to set the context for the development and sharing of best-practice guidelines. PATIENTS AND METHODS. This was a retrospective, descriptive study that used data from the Organ Procurement and Transplantation Network/United Network for Organ Sharing database from 1993 to 2005. Organ data from all donors after cardiac death who were <18 years of age were analyzed. The list of donor medical centers was then cross-referenced with the member list from the National Association of Childrens Hospitals and Related Institutions. RESULTS. There were 683 organs from donation-after-cardiac-death donors <18 years of age. Of those, <5% were used for pediatric recipients. In comparison, ∼20% of non–donation-after-cardiac-death organs from pediatric donors were used for pediatric recipients. The vast majority of donation-after-cardiac-death organs donated were kidneys and livers. More than 50% of medical centers that had a pediatric organ-donation-after-cardiac-death donor had just 1. The medical center with the largest pediatric organ-donation-after-cardiac-death donation experience had 14 donors. Forty-three percent of medical centers that had ≥1 pediatric donation-after-cardiac-death donor were members of the National Association of Childrens Hospitals and Related Institutions. Fifty-six percent of all of the pediatric donation-after-cardiac-death organs were donated from the National Association of Childrens Hospitals and Related Institution member centers. CONCLUSIONS. Data regarding the use of pediatric donation-after-cardiac-death organs for pediatric recipients remain sparse. Few medical centers have had enough donation-after-cardiac-death donor experience to report a tried-and-true approach. We advocate for comprehensive collection and reporting of outcome data for all-aged recipients of pediatric donation-after-cardiac-death organs to help facilitate the generation of evidence-based best-practice guidelines for pediatric donation after cardiac death.

Pathophysiology of right ventricular failure in pulmonary hypertension

This review focuses on right ventricular anatomy and function and the significance of ventricular interdependence in the response of the right ventricle to an increase in afterload. This is followed by a discussion of the pathophysiology of right ventricular failure in pulmonary arterial hypertension as well as in other clinical syndromes of pulmonary hypertension. Pulmonary hypertension is common in critically ill children and is associated with several conditions. Regardless of the etiology, an increase in right ventricular afterload leads to a number of compensatory changes in cardiovascular physiology. These changes are not altogether intuitive and require an understanding of right ventricular physiology and ventricular interdependence to optimize the care of these patients.

Intensivist-led team approach to critical care of children with heart disease [7]

To the Editor. We read with great interest the article “ACC/AHA/AAP Recommendations for Training in Pediatric Cardiology.”1 We would like to comment specifically on the section that described advanced training in pediatric cardiac critical care. The practice of high-quality postoperative pediatric cardiac intensive care requires a multidisciplinary collaboration between physicians (surgeon, cardiologist, intensivist) and other clinical disciplines including nursing, respiratory therapy, pharmacology, and nutrition support. Our comments are predicated on the well-established precept that all critically ill patients are best cared for by a multidisciplinary team of clinicians with the intensivist as the team leader or co-leader.2–5 On the basis of data demonstrating better outcomes and decreased costs, groups …

High-frequency oscillatory ventilation in the management of infants with pulmonary hemorrhage after cardiac surgery

p ULMONARY hemorrhage immedmtely after cardiopulmonary bypass (CPB) is an infrequent, catastrophic event. There is only one such case reported in the literature) The authors recently encountered three mfants who suffered massive pulmonary hemorrhage after cardiac surgery for correction of congenital cardiac anomalies. The cause and nature of the hemorrhages remain unclear. However, the intent of this report is to describe the effective use of high-frequency oscillatory ventilation m two of these infants.

An Elevated Low Cardiac Output Syndrome Score Is Associated With Morbidity in Infants After Congenital Heart Surgery.

Objectives: To evaluate an empirically derived Low Cardiac Output Syndrome Score as a clinical assessment tool for the presence and severity of Low Cardiac Output Syndrome and to examine its association with clinical outcomes in infants who underwent surgical repair or palliation of congenital heart defects. Design: Prospective observational cohort study. Setting: Cardiac ICU at Seattle Children’s Hospital. Patients: Infants undergoing surgical repair or palliation of congenital heart defects. Interventions: None. Measurements and Main Results: Clinical and laboratory data were recorded hourly for the first 24 hours after surgery. A Low Cardiac Output Syndrome Score was calculated by assigning one point for each of the following: tachycardia, oliguria, toe temperature less than 30°C, need for volume administration in excess of 30 mL/kg/d, decreased near infrared spectrometry measurements, hyperlactatemia, and need for vasoactive/inotropes in excess of milrinone at 0.5 &mgr;g/kg/min. A cumulative Low Cardiac Output Syndrome Score was determined by summation of Low Cardiac Output Syndrome Score on arrival to cardiac ICU, and 8, 12, and 24 hours postoperatively. Scores were analyzed for association with composite morbidity (prolonged mechanical ventilation, new infection, cardiopulmonary arrest, neurologic event, renal dysfunction, necrotizing enterocolitis, and extracorporeal life support) and resource utilization. Fifty-four patients were included. Overall composite morbidity was 33.3%. Median peak Low Cardiac Output Syndrome Score and cumulative Low Cardiac Output Syndrome Score were higher in patients with composite morbidity (3 [2–5] vs 2 [1–3]; p = 0.003 and 8 [5–10] vs 2.5 [1–5]; p < 0.001)]. Area under the receiver operating characteristic curve for cumulative Low Cardiac Output Syndrome Score versus composite morbidity was 0.83, optimal cutoff of greater than 6. Patients with cumulative Low Cardiac Output Syndrome Score greater than or equal to 7 had higher morbidity, longer duration of mechanical ventilation, cardiac ICU, and hospital length of stay (all p ⩽ 0.001). After adjusting for other relevant variables, peak Low Cardiac Output Syndrome Score and cumulative Low Cardiac Output Syndrome Score were independently associated with composite morbidity (odds ratio, 2.57; 95% CI, 1.12–5.9 and odds ratio, 1.35; 95% CI, 1.09–1.67, respectively). Conclusion: Higher peak Low Cardiac Output Syndrome Score and cumulative Low Cardiac Output Syndrome Score were associated with increased morbidity and resource utilization among infants following surgery for congenital heart defects and might be a useful tools in future cardiac intensive care research. Independent validation is required.