Ian Adatia

Regional and central venous oxygen saturation monitoring following pediatric cardiac surgery: concordance and association with clinical variables.

Objective: To compare changes in regional cerebral or flank oxygen saturation measured by near-infrared spectroscopy with changes in central venous oxygen saturation (Scvo2) and to determine clinical variables associated with these changes. Design: Prospective observational cohort study. Setting: University tertiary care center, pediatric cardiac intensive care unit. Patients: Seventy postoperative congenital cardiac surgical patients (median age 0.3 yrs; interquartile range 0.02–0.46 yrs). Interventions: None. Measurements and Main Results: We measured temporally correlated regional oxygen saturation (rSo2) with hematologic (hematocrit), biochemical (arterial blood gas, Scvo2, and lactate) and physiologic (temperature, heart rate, mean blood pressure, and pulse oximetry) variables in the first postoperative day. Cerebral and flank rSo2 were strongly correlated with Scvo2, in both cyanotic or acyanotic patients and single- or two-ventricle physiology with and without aortic arch obstruction (all p < .001). However, individual values had wide limits of agreement on Bland-Altman analysis. The correlations of change in these measurements were weaker but still significant (all p < .0001), again with wide limits of agreement. Similar direction of change in cerebral rSo2 and Scvo2 was present 64% (95% confidence interval, 55–73%) of the time. Change in arterial pressure of carbon dioxide (&Dgr;Paco2) was associated with cerebral &Dgr;rSo2 (&Dgr;Paco2 &bgr; = 0.35, p < .0001) but not flank &Dgr;rSo2 or &Dgr;Scvo2. A pattern of relative cerebral desaturation (flank rSo2 > cerebral rSo2) was noted in a majority of patients (81%) with two-site monitoring regardless of bypass method or age. Conclusions: Neither individual values nor changes in rSo2 are interchangeable measures of Scvo2 in postoperative pediatric cardiac patients. The unique relationship between changes in Paco2 and cerebral rSo2 supports the hypothesis that cerebral near-infrared spectroscopy monitors regional cerebral oxygenation. Clinical application of this monitor must include recognition of the clinical variables that affect regional brain oxygenation.

Sudden Unexpected Death in Children with Heart Disease

OBJECTIVEnTo review a mortality database, and identify all sudden unexpected deaths in patients followed by the cardiac program.nnnDESIGNnRetrospective review of prospectively maintained database.nnnRESULTSnOver 8 years, we identified 80 sudden unexpected deaths, among which there were sufficient data in 69 (24 females). Patients died at a median age of 17.2 months (28 days-18.8 years). Forty-six patients had 2 functional ventricles and 23 had received palliation for a single-functional ventricle. Patients with a single ventricle died at a younger age (median 120 days; 28 days-17.2 years) and sooner after last assessment (median 27 days; 1-146 days) than patients in the biventricular group (median age 2 years; 43 days-18.8 years; median time since last assessment 49 days, 1 days-1 year) (P < .01; P = .01). Thrombosis was the most common cause (61%) of death in the single-ventricle group. Arrhythmia or presumed arrhythmia was the most common cause (46%) of death in the biventricular group. Fifty-one patients had undergone surgery. Six patients had primary electrophysiological disease, and 5 had cardiomyopathy. Eight deaths occurred in patients with pulmonary vascular disease.nnnCONCLUSIONnOur study demonstrates that sudden unexpected death occurred at a frequency of at least 10 patients per year over an 8-year period with 55,730 patient encounters. We were able to determine a clinical cause of death in most patients. Arrhythmias (30%) and pulmonary vascular disease (13%) are important causes of sudden death. Simple aortic valve disease and hypertrophic cardiomyopathy are rare (4%) causes of sudden death in childhood. Infants and young children with surgical shunts comprise 23% of sudden unexpected deaths that occur within a month of the last evaluation. Close surveillance of these patients is warranted.

Perioperative B-type natriuretic peptide levels predict outcome after bidirectional cavopulmonary anastomosis and total cavopulmonary connection

OBJECTIVEnThe objective of the study was to determine perioperative B-type natriuretic peptide levels in infants and children undergoing bidirectional cavopulmonary anastomosis or total cavopulmonary connection, and the predictive value of B-type natriuretic peptide levels for outcome.nnnMETHODSnPlasma B-type natriuretic peptide levels were measured before and 2, 12, and 24 hours after surgery in 36 consecutive patients undergoing bidirectional cavopulmonary anastomosis (n = 25) or total cavopulmonary connection (n = 11). B-type natriuretic peptide levels were evaluated as predictors of outcome.nnnRESULTSnB-type natriuretic peptide levels increased after surgery, peaking at 12 hours in most patients. In the bidirectional cavopulmonary anastomosis group, patients with 12-hour B-type natriuretic peptide > or = 500 pg/mL had a longer duration of mechanical ventilation (165 +/- 149 hours vs 20 +/- 9 hours, P = .004), longer intensive care unit stay (11 +/- 7 days vs 4 +/- 2 days, P = .001), and longer hospital stay (20 days +/- 12 vs 9 days +/- 5, P = .003). A 12-hour B-type natriuretic peptide > or = 500 pg/mL had a sensitivity of 80% and a specificity of 80% for predicting an unplanned surgical or transcatheter cardiac intervention, including transplantation (P = .03). In the total cavopulmonary connection group, preoperative B-type natriuretic peptide levels were highest in patients with total cavopulmonary connection failure compared with patients with a good outcome (88 +/- 46 pg/mL vs 15 +/- 6 pg/mL, P = .03).nnnCONCLUSIONnPostoperative B-type natriuretic peptide levels predict outcome after bidirectional cavopulmonary anastomosis, and preoperative levels are greater in patients with both early and late total cavopulmonary connection failure compared with patients with a good outcome.

The role of calcium channel blockers, steroids, anticoagulation, antiplatelet drugs, and endothelin receptor antagonists.

The rationale for the drug therapy of pulmonary artery hypertension is to reduce mortality and morbidity caused by failure of right ventricular adaptation to an elevated pulmonary vascular resistance. We review the evidence for the use of calcium-channel blockers, steroids, anticoagulation, antiplatelet drugs, and endothelin receptor antagonists in the management of pulmonary artery hypertension. The drugs we discuss are more suited to long-term outpatient therapy. These drugs have not found a routine place in intensive care management, and calcium-channel blockers are contraindicated in patients with right-heart failure. The efficacy of many agents has been extrapolated from data acquired in adult patients and applied to children. All of us involved in the care of young patients with pulmonary artery hypertension should advocate for both the inclusion of younger patients in clinical trials and the design of distinctly pediatric trials with pharmaceutical and drug administration agencies. It is only with data derived from pediatric inclusive studies that we shall be able to recommend therapy with strong evidence. However, it is important to point out that the use of newer agents for the treatment of chronic pulmonary artery hypertension (prostacyclin, endothelin receptor antagonists, nitric oxide, and sildenafil) have not been shown to improve survival unequivocally and have relied on surrogates, such as exercise capacity. There are no long-term studies of survival benefit. Recent studies have included data on time to clinical worsening, which may be a more predictive surrogate of survival.