RESUMO

A complex vascular abnormality in the lungs, termed alveolar capillary dysplasia (ACD) and misalignment of the lung vessels, has been recently recognized in some infants with persistent pulmonary hypertension. These infants die despite maximal medical support including extracorporeal membrane oxygenation (ECMO). Inhaled nitric oxide has been reported to improve oxygenation in neonates with persistent pulmonary hypertension of the newborn, and may allow some infants to avoid the need for ECMO. We identified five infants who had received inhaled nitric oxide to treat refractory hypoxemia caused by persistent pulmonary hypertension of the newborn, and who subsequently died and had autopsy confirmation of ACD. Each infant received care at a different medical center. In each patient, inhaled NO increased the arterial partial pressure of oxygen dramatically. Despite initial clinical improvement, the response to NO was not sustained in any patient. As responsiveness was lost, each infant with ACD required inhaled NO concentrations of 80 ppm or higher to sustain oxygenation. Each infant died, four after extensive periods of ECMO support. This experience demonstrates that a short-term improvement after inhalation of nitric oxide does not lead to long-term survival in ACD. Further, in three infants the diagnosis of ACD was established by lung biopsy before death. Increasing awareness of this clinical entity may allow for the avoidance of costly, invasive procedures such as ECMO until more specific therapies become available.

Assuntos

RESUMO

Excess nitric oxide is a mediator of the hypotension in septic shock. Nitric oxide dilates vascular smooth muscle through activation of soluble guanylate cyclase. We report the increase in blood pressure caused by methylene blue (MB), a soluble guanylate cyclase inhibitor, in five neonates with presumed septic shock unresponsive to colloids, inotropic agents, and corticosteroids. MB was given intravenously at a dose of 1 mg/kg during a 1-hour period. MB increased blood pressure in each patient (average, 33% +/- 20%). Blood pressure subsequently decreased to near baseline values in three patients, who then received a second infusion of MB. Blood pressure again increased in these patients. Three of five patients were weaned from inotropic support within 72 hours. Three of five patients survived and were discharged home. We suggest that MB increased blood pressure in these neonates with refractory hypotension.

Assuntos

RESUMO

In an effort to obtain data to provide the basis for the design of controlled clinical trials, we contacted all U.S. participants in the National ECMO Registry to assemble the national experience on the use of extracorporeal membrane oxygenation in respiratory syncytial virus bronchiolitis during the past 5 years. Twelve infants were treated at nine centers between 1983 and 1988. Eight had been born prematurely, and five had bronchopulmonary dysplasia. The mean age at onset of infection with respiratory syncytial virus was 108 +/- 102 days. The mean length of ventilator management before extracorporeal membrane oxygenation was 7.8 +/- 7.1 days. All infants had persistent hypoxemia with a mean arterial oxygen pressure of 39.2 +/- 11.7 torr (5.3 +/- 1.6 kPa) despite high ventilator pressures (mean airway pressure 19.7 +/- 6.4 cm H2O) and 100% inspired oxygen; six had air leak syndrome. Seven infants survived (58%). The mean duration of extracorporeal membrane oxygenation for survivors was 233 +/- 139 hours. Preexisting chronic lung disease did not predict a poor outcome: four of the five infants with bronchopulmonary dysplasia survived. Six of the survivors have subsequently achieved expected developmental milestones and one has slight motor delay. We conclude that, for infants with severe respiratory syncytial virus bronchiolitis whose condition deteriorates despite maximal ventilator management, extracorporeal membrane oxygenation may provide lifesaving support. The duration of successful treatment with this therapy may be longer than that for conventional neonatal indications, but excellent neurologic outcome may be expected in survivors.

Assuntos

Assuntos

RESUMO

We studied the cause of hemolysis during extracorporeal membrane oxygenation (ECMO) by monitoring hematologic and coagulation profiles in seven consecutive infants treated with this procedure. A constrained vortex pump was used in all patients, and the average duration of ECMO was 224 +/- 111 (SD) hours. In all patients, plasma free hemoglobin was low during the first 48 hours after the initiation of ECMO. Later, when visible clots appeared in the ECMO circuit, plasma hemoglobin progressively rose. A rise in the level of fibrin degradation products and a fall in the fibrinogen level were observed concurrently with a rise in the plasma hemoglobin level. After complete circuit changes in six patients, plasma free hemoglobin, fibrin split products, and fibrinogen all returned to baseline values. Neither circuit component changes nor exchange transfusion was effective in normalizing the levels of plasma free hemoglobin, fibrin split products, and fibrinogen. We conclude that when ECMO is administered for prolonged periods, circuit thrombosis occurs and hemolysis ensues. Additional studies are needed to assess the contribution of the constrained vortex pump to this process.

Assuntos