Mary B. Taylor

Extracorporeal membrane oxygenation in children after repair of congenital cardiac lesions

BACKGROUND The purpose of this study was to review our experience in the early application of extracorporeal membrane oxygenation (ECMO) in patients requiring mechanical assistance after cardiac surgical procedures. METHODS The hospital records of all children requiring ECMO after cardiac operation were retrospectively reviewed, and an analysis of variables affecting survival was performed. RESULTS Fifty pediatric patients between May 1997 and October 2000 required ECMO for cardiopulmonary support after cardiac operation. Patients ranged in age from 1 day to 11 years (median age, 40 days). Forty-eight patients underwent repair of congenital cardiac lesions and 2 were included after receiving a heart transplant. Twenty-two children could not be weaned from cardiopulmonary bypass and were placed on ECMO in the operating room for circulatory support. Of the 28 children who required ECMO in the intensive care unit, 10 had ECMO instituted after cardiopulmonary arrest (mean cardiopulmonary resuscitation time 42 minutes; range, 5 to 110 minutes). In infants with single-ventricle physiology, survival to discharge was 61% (11 of 18 patients) as compared with 43% (14 of 32 patients) in those with biventricular physiology. Thirty of the 50 patients (60%) were successfully weaned from ECMO, of which 25 (83%) were discharged home. Overall survival to discharge in the entire cohort was 50%. Extracorporeal membrane oxygenation support greater than 72 hours was a grave prognostic indicator. Overall survival in this group was 36% (9 of 25 patients) compared with 56% (14 of 25 patients) in those with ECMO support less than 72 hours (p < 0.05). Univariate analysis revealed the presence of renal failure, extended periods of circulatory support, and a prolonged period of cardiopulmonary resuscitation as risk factors for mortality. The presence of shunt-dependent flow, operative procedure, and institution of ECMO in the intensive care unit did not alter survival. CONCLUSIONS Extracorporeal membrane oxygenation provides effective support for postoperative cardiac and pulmonary failure refractory to medical management. Early institution of ECMO may decrease the incidence of cardiac arrest and end-organ damage, thus increasing survival in these critically ill patients.

Acute renal failure during extracorporeal support in the pediatric cardiac patient.

End-organ dysfunction is associated with increased mortality in pediatric cardiac patients requiring extracorporeal support. We sought to characterize the odds of developing acute renal failure (ARF) as well as associated increases in mortality in this population. Records of all cardiac patients in our pediatric intensive care unit receiving extracorporeal membrane oxygenation (ECMO) over a 24 month period were reviewed for data with respect to their course. Acute renal failure was defined as fluid retention or electrolyte disturbance resulting in institution of continuous renal replacement therapy (CRRT), or a glomerular filtration rate (GFR) of <35 ml/min/1.73 m2. Analysis revealed 49 ECMO runs in 48 patients, with ARF present in 71.7%, and CRRT initiated in 58.7%. Odds for developing ARF increased by 60% per day of ECMO support (β 1.60, 95% CI 1.08–2.37, p = 0.018). Acute renal failure during ECMO, after adjusting for patient age, remained associated with a decrease in odds of survival to discharge (OR 4.7, 95% CI 1.10–20.4, p = 0.037). We conclude that ARF is more common among pediatric cardiac patients requiring extracorporeal support than previously recognized. Increasing duration of ECMO support is associated with development of ARF. Acute renal failure while on ECMO is associated with a significant decrease in the odds of survival in the pediatric cardiac patient.

Clinical outcomes of 84 children with congenital heart disease managed with extracorporeal membrane oxygenation after cardiac surgery.

The purpose of our research was to study the clinical outcomes of children with congenital heart disease (CHD) requiring extracorporeal membrane oxygenation (ECMO) support after cardiac surgery at a tertiary care childrens hospital. Retrospective review of all patients with CHD who required postcardiotomy ECMO between January 2001 and September 2004 (45 months) was undertaken. Various outcome predictors were tested for any association with survival to hospital discharge using univariate analysis. A total of 84 children were placed on ECMO after CHD surgery; 39 (46.4%) were placed on ECMO in the operating room. Median age of the patients was 128 days (1 day to 5 years) and median weight was 4.53 kg (2–18 kg). Active cardiopulmonary resuscitation was ongoing at the time of cannulation in 27 children (32%). Fifty-two children (61.9) survived > 24 hours after decannulation and 31 (36.9%) survived to discharge. High arterial serum lactate levels at the time of ECMO initiation were strongly correlated with nonsurvival (p = 0.004). Nonsurvivors had longer duration on ECMO than survivors (p = 0.003). The odds of survival dropped significantly after 144 hours (day 6) of ECMO. ECMO support results in improved outcomes in patients who suffered hemodynamic collapse post cardiac surgery. Underlying cardiac lesion, age, weight, gender, initial arterial pH, location of ECMO initiation, need for hemofiltration and placement of ECMO after active ongoing cardiopulmonary resuscitation did not increase the mortality risk. Initial arterial serum lactate level and inability to wean off by 6 days were strongly correlated with nonsurvival.

Suboptimal Inhibition of Platelet Cyclooxygenase-1 by Aspirin in Metabolic Syndrome

Interindividual variation in the ability of aspirin to inhibit platelet cyclooxygenase-1 (COX-1) could account for some on-treatment cardiovascular events. Here, we sought to determine whether there are clinical phenotypes that are associated with a suboptimal pharmacological effect of aspirin. In a prospective, 2-week study, we evaluated the effect of aspirin (81 mg) on platelet COX-1 in 135 patients with stable coronary artery disease by measuring serum thromboxane B2 (sTxB2) as an indicator of inhibition of platelet COX-1. A nested randomized study compared enteric-coated with immediate-release formulations of aspirin. We found that sTxB2 was systematically higher among the 83 patients with metabolic syndrome than among the 52 patients without (median: 4.0 versus 3.02 ng/mL; P=0.013). Twelve patients (14%) with metabolic syndrome, but none without metabolic syndrome, had sTxB2 levels consistent with inadequate inhibition of COX (sTxB2 ≥13 ng/mL). In linear regression models, metabolic syndrome (but none of its individual components) significantly associated with higher levels of log-transformed sTxB2 (P=0.006). Higher levels of sTxB2 associated with greater residual platelet function measured by aggregometry-based methods. Among the randomized subset, sTxB2 levels were systematically higher among patients receiving enteric-coated aspirin. Last, urinary 11-dehydro thromboxane B2 did not correlate with sTxB2, suggesting that the former should not be used to quantitate aspirins pharmacological effect on platelets. In conclusion, metabolic syndrome, which places patients at high risk for thrombotic cardiovascular events, strongly and uniquely associates with less effective inhibition of platelet COX-1 by aspirin.

Fundamentals of management of acute postoperative pulmonary hypertension.

In the last several years, there have been numerous advancements in the field of pulmonary hypertension as a whole, but there have been few changes in the management of children with pulmonary hypertension after cardiac surgery. Patients at particular risk for postoperative pulmonary hypertension can be identified preoperatively based on their cardiac disease and can be grouped into four broad categories based on the mechanisms responsible for pulmonary hypertension: 1) increased pulmonary vascular resistance; 2) increased pulmonary blood flow with normal pulmonary vascular resistance; 3) a combination of increased pulmonary vascular resistance and increased blood flow; and 4) increased pulmonary venous pressure. In this review of the immediate postoperative management of pulmonary hypertension, various strategies are discussed including medical therapies, monitoring, ventilatory strategies, and weaning from these supports. With early recognition of patients at particular risk for severe pulmonary hypertension, management strategies can be directed at preventing or minimizing hemodynamic instability and thereby prevent the development of ventricular dysfunction and a low output state.

Extra corporeal membrane oxygenation and plasmapheresis for pulmonary hemorrhage in microscopic polyangiitis

Early initiation of extracorporeal membrane oxygenation to treat acute hypoxemic respiratory failure secondary to massive pulmonary hemorrhage in microscopic polyangiitis in children can be life-saving while awaiting control of the autoimmune disease process by plasmapheresis and immunosuppression.

Methemoglobinemia: Toxicity of inhaled nitric oxide therapy.

Elevation in methemoglobin is a known toxicity of inhaled nitric oxide (NO) therapy. This article describes two significant episodes of methemoglobinemia. These cases illustrate the probable cause and the treatment strategies for the potential for delivery of high concentrations of NO, resulting in methemoglobinemia with moderate and even low-dose delivered NO. We propose mechanisms for this occurrence and means of prevention.

Complex Febrile Seizures Followed by Complete Recovery in an Infant with High-Titer 2009 Pandemic Influenza A (H1N1) Virus Infection

ABSTRACT We describe a 2009 H1N1 virus infection with a high viral load in a previously healthy infant who presented with complex febrile seizures and improved on oseltamivir without neurologic sequelae. Febrile seizures may be a complication in young children experiencing infection with high viral loads of 2009 H1N1 influenza virus.

Low incidence of significant valvar insufficiency following retrograde aortic radiofrequency catheter ablation in young patients.

The incidence of significant valvar insufficiency at late (>6 month) follow-up was retrospectively evaluated in 27 young patients (age 4.0–18.0 years) undergoing 29 ablation procedures via the retrograde aortic approach for left-sided accessory connections in whom pre-ablation and post-ablation echocardiograms were available for review. Valvar insufficiency was graded using color flow techniques as absent, trivial, mild, moderate, or severe by blinded reviewers. Ablation was acutely successful via the retrograde approach in 25 of 29 procedures among these 27 patients. Successful ablation was ultimately achieved in all 27 patients.At baseline, 7 patients had evidence of trivial or mild mitral insufficiency, and no patient had aortic insufficiency. Three patients had evidence of impaired left ventricular systolic performance in the presence of manifest pre-excitation. At follow-up, pre-existing mitral insufficiency resolved in 5/7 patients, and persisted in 2 patients. New mitral insufficiency was evident in 3 patients, and new aortic insufficiency was transiently evident in 1 patient following ablation (all trivial). Institutional experience (mean rank 10 cases vs. 33 cases, p < .0005), and lower patient weight (29.7 vs. 56.3 kilograms, p = .01) were the only factors associated with the development of new valvar insufficiency. Valvar insufficiency could not be detected by careful auscultation in any patient and was deemed clinically insignificant in all patients.We conclude that ablation of left-sided accessory connections can be performed via the retrograde aortic approach without creating clinically significant valvar insufficiency.

Percutaneous Closure of Perimembranous Ventricular Septal Defects Using the Second-Generation Amplatzer Vascular Occluders.

Earlier attempts at percutaneous closure of perimembranous ventricular septal defects (Pm VSDs) were abandoned because of incidence of heart block likely as a result of device rigidity and/or oversizing. This is retrospective review and data reporting of patients who underwent percutaneous closure using the softer second-generation Amplatzer vascular occluders; namely the Amplatzer vascular plug, second generation, (AVP II) and the Amplatzer duct occluder, second generation (ADO II) in our institution. A total of 20 patients were identified; AVP II was used in 9 patients and ADO II in 11 patients. Median weight was 13.45 kg (range 6.5 to 76); age 28.5 months (range 11 to 352). After procedure, 4 were noted to have aortic insufficiency; trivial in 3 and mild in 1 (unrelated to the device). Mild tricuspid regurgitation possibly device or procedure related was seen in 4. Residual flow through the device was common after procedure and disappeared in all but 3, graded as trivial in 1, small in 2. Average follow-up period was 7.54 months ± 7.5 (1 day to 25 months). There was no incidence of heart block, bacterial endocarditis, hemolysis, device embolization, or fracture. The aortic insufficiency resolved in 1 patient and was estimated to be trivial in the remaining 3 patients. In conclusion, percutaneous closure of Pm VSDs using the softer new generation devices as the AVP II and the ADO II is feasible and safe. Longer follow-up and larger series are needed.