Low-dose inhaled nitric oxide improves the oxygenation and ventilation of infants and children with acute, hypoxemic respiratory failure.

OBJECTIVE: To describe the effects of inhaled nitric oxide on oxygenation and ventilation in patients with acute, hypoxic respiratory failure and to characterize those who respond to low doses with a significant improvement in PaO2. DESIGN: Prospective dose response trial of inhaled nitric oxide. Patients who demonstrated a > or =15% improvement in PaO2 were randomized to receive conventional mechanical ventilation with or without prolonged inhaled nitric oxide. SETTING: Pediatric intensive care unit of a tertiary care children's hospital serving as a regional referral center for respiratory failure. PATIENTS: Pediatric patients with an acute parenchymal lung disease requiring mechanical ventilation, an F(IO2) of > or =0.5, a positive end-expiratory pressure of > or =7 cm H2O, and whose PaO2/FIO2 ratio was < or =160. INTERVENTIONS: PaO2, PaCO2, pH, heart rate, blood pressure, and methemoglobin were recorded at baseline and after inhaling 1, 5, 10, and 20 ppm of nitric oxide. Peak expiratory flow rate and mean airway resistance were measured while subjects received 0 and 20 ppm of inhaled nitric oxide. Patients were followed up until extubation or death. MEASUREMENTS AND MAIN RESULTS: Twenty-six patients (median age, 2.6 yrs [range, 1 mo-18.2 yrs]) were enrolled in the study. PaO2 increased (p< .001) and Pa(CO2) fell (p< .0001) from baseline with the administration of inhaled nitric oxide. There was no statistical difference among 1, 5, 10, and 20 ppm with regard to effects on oxygenation. Sixteen patients (62%) responded to inhaled nitric oxide with a > or =15% improvement in PaO2; 14 of these responses occurred at a dose of 1 or 5 ppm. Response to inhaled nitric oxide was not associated with age, length of intubation, presence of primary lung disease, chest radiograph, or illness severity. Among patients weighing < or =20 kg, responders showed a greater fall in mean airway resistance (p < .05) than nonresponders. Mortality was not influenced by prolonged inhaled nitric oxide when analyzed by intention to treat. Patients receiving prolonged inhaled nitric oxide at doses of < or =20 ppm maintained methemoglobin levels of <3.0% and circuit concentrations of NO2 of <1 ppm. CONCLUSIONS: Inhaled nitric oxide at doses of < or =5 ppm improves the oxygenation and (to a lesser extent) ventilation of most children with acute, hypoxic respiratory failure. The unpredictable response of patients necessitates individualized dosing of inhaled nitric oxide, starting at concentrations of < or =1 ppm. Inhaled nitric oxide at < or =20 ppm may exert a small salutary effect on bronchial tone. The benefits of prolonged inhaled nitric oxide remain unknown.

Extracorporeal membrane oxygenation for nonneonatal pulmonary and multiple-organ failure.

PURPOSE: Extracorporeal membrane oxygenation (ECMO) is an accepted therapy for neonatal pulmonary failure, but its use in older children has been controversial. METHODS: Over 13 years, 55 children (ages, 3 months to 16 years) were treated with venoarterial or venovenous ECMO. The diagnoses were viral, bacterial, or fungal pneumonia (24 patients); hydrocarbon or gastric aspiration (n = 10); adult respiratory distress syndrome (ARDS), sepsis, near drowning (n = 15); pulmonary contusion (n = 2); airway obstruction (n = 3); pulmonary artery foreign body (n = 1). Pre-ECMO blood gas ranges (and means) were PO2, 21 to 100 (n = 44); PCO2, 23 to 125 (n = 72); pH, 6.81 to 7.55 (n = 7.11). RESULTS: All patients received inotropes, and 38 required dialysis or hemofiltration. ECMO was used for 20 to 613 hours (mean, 196 hours). Patient complications included cannulation site hemorrhage (n = 40), renal failure (n = 10), seizures (n = 8), stroke (n = 3), and cerebral hemorrhage (n = 2). Twenty-five patients (45%) survived ECMO, with 21 long-term survivors (10 pneumonia, five aspiration, five ARDS, one pulmonary contusion), five of whom have mild to moderate neurological deficit. Patients with combinations of pulmonary, cardiac, and renal failure, or sepsis did not survive. CONCLUSIONS: ECMO is an invasive technique that can be life saving in the child with isolated respiratory failure, but its usefulness in children with multiorgan failure is less certain.

Improved survival in congenital diaphragmatic hernia with evolving therapeutic strategies.

OBJECTIVE: To compare the survival rates for 3 therapeutic eras, each using different treatment strategies for the management of newborns with congenital diaphragmatic hernia (CDH). DESIGN: Retrospective review of all infants with CDH from 1970 through 1997. SETTING: Tertiary care children's hospital. PARTICIPANTS: A total of 203 newborns with CDH. INTERVENTIONS: Extracorporeal membrane oxygenation (ECMO) was performed with arterial and venous cannulation connected to a membrane oxygenatorroller pump perfusion apparatus, using systemic heparinization. Delayed operative therapy involved operative repair 2 to 5 days after birth using preoperative ventilation support only. Since 1970, 203 newborns with CDH were managed in 3 therapeutic eras: era 1 (1970-1983, 102 patients) was immediate CDH repair with postoperative ventilator and pharmacologic support; era 2 (1984-1988, 45 patients) was immediate repair with postoperative ventilator support (18 patients), immediate ECMO with CDH repair on ECMO (4 patients), or immediate repair with postoperative ECMO (23 patients); and era 3 (1989-1997, 56 patients) was immediate ECMO with repair on ECMO (23 patients), immediate repair with postoperative ECMO (9 patients), or delayed (2-5 days) CDH repair (24 patients). MAIN OUTCOME MEASURES: Survival, defined as discharge from the hospital, and morbidity. RESULTS: Survival was 42% (43/102 patients) in era 1, 58% (26/45 patients) in era 2, and 79% (44/56 patients) in era 3 (P<.02 vs eras 1 and 2). In era 3, the survival for immediate ECMO with repair on ECMO was 57% (13/23 patients), 89% (8/9 patients) for immediate repair with postoperative ECMO, and 96% (23/24 patients) for delayed repair. Eight late deaths were caused by pulmonary hypertension (1 death), sudden infant death syndrome (1 death), and other causes (6 deaths). Morbidity in survivors included mild neurologic deficit (5 patients) and pulmonary disease (3 patients). CONCLUSION: These data demonstrate a significant improvement in survival in CDH with preoperative ECMO and with delayed repair with and without ECMO support and suggest that immediate repair of CDH without the availability of ECMO support should be abandoned.

The effects of venous occlusion on cerebral blood flow characteristics during ECMO.

Extracorporeal membrane oxygenation (ECMO) in the newborn usually requires occlusion of a jugular vein, and frequently a carotid artery. The acute effects of jugular vein occlusion on cerebral blood flow characteristics have received little investigation. Six newborns (age range, 0 to 5 days; weight, 2.4 to 3.1 kg) were treated with venoarterial ECMO, with additional placement of a cephalic venous catheter, for meconium aspiration (4) or persistent fetal circulation (2). Doppler duplex ultrasound evaluation of blood flow velocity and resistive index (RI) in the right (RMCA) and left (LMCA) middle cerebral arteries was performed just before ECMO, immediately after ECMO onset, and at 8,24, and 48 hours of ECMO. Arterial Po2 was maintained at 80 to 120 mm Hg. Pco2 at 35 to 45 mm Hg. and mean arterial pressure at 50 to 60 mm Hg. Flow velocity was measured with the cephalic venous catheter both open and closed. Closure of the cephalic venous cannula resulted in an abrupt, significant reduction in RMCA flow velocity and a significant increase in RI at the onset of ECMO and at 8 hours of ECMO. Opening the cannula restored the velocity and RI to normal. LMCA velocity and RI did not change with closure of the cephalic venous cannula. All infants survived ECMO, and five of the six are normal neurologically at 1 year of age. These data show that right carotid ligation alone did not change cerebral arterial blood flow velocity, but the addition of venous occlusion significantly decreased RMCA flow velocity, which was alleviated by cephalic venous drainage. After 24 hours of ECMO, this effect disappeared. This suggests that cephalic venous drainage may help prevent the neurological complications of ECMO by maintaining normal cerebral blood flow.

Prolonged extracorporeal support for nonneonatal respiratory failure.

Extracorporeal membrane oxygenation (ECMO) is effective for newborns with pulmonary failure unresponsive to conventional therapy. However, ECMO for the older child and adult has been controversial and not widely utilized. Over 4 years, 24 patients (aged 4 months to 16 years; 11 boys, 13 girls) underwent venoarterial ECMO (duration, 7 to 19 days) for respiratory failure. The diagnoses were: viral pneumonia (7), hydrocarbon aspiration (6), sepsis with adult respiratory distress syndrome (ARDS) (2), bacterial pneumonitis (2), tracheal stenosis (1), bilateral pulmonary contusion (1), diaphragmatic hernia with ARDS (1), ketoacidosis with ARDS (1), pulmonary artery injection of hydrocarbon (1), drowning (1), and epiglottis with barotrauma (1). Pre-ECMO blood gas ranges (and means) were PO2 18 to 65 (46), and PCO2 47 to 112 (65). Nineteen patients received dopamine, dobutamine, or other inotrope for associated cardiac and/or renal failure. Cannulation for ECMO was through neck or groin vessels in 17, and sternotomy in 7. ECMO flow rates were 150 to 250 mL/kg/min, to maintain PO2 greater than 100 and PCO2 less than 40. Nine patients (41%) survived ECMO, with eight long-term survivors, (4 hydrocarbon aspiration or injection, 1 pulmonary contusion, 1 viral pneumonia, 1 ARDS, 1 barotrauma), three of whom have mild neurological deficit. All patients with sternotomy, and 8 of 15 with neck and/or groin cannulation, required 1 to 5 explorations for hemorrhage while on ECMO. All survivors had primarily pulmonary failure; patients with combinations of pulmonary, cardiac, and renal failure did not survive. ECMO can be life-saving in the child with isolated pulmonary failure, but its efficacy in patients with multiorgan failure is uncertain.

Congenital diaphragmatic hernia repair on ECMO.

Congenital diaphragmatic hernia (CDH) with severe respiratory failure in the first few hours of life continues to be associated with significant mortality. Extracorporeal membrane oxygenation (ECMO) has been successfully used postoperatively to reverse the effects of severe pulmonary hypertension. Since 1984, ECMO has been required in 27 of the patients we treated with CDH. This report describes our experience with six very high-risk patients placed on ECMO prior to the operation who subsequently underwent repair of their diaphragmatic hernias while on ECMO. Two patients presented in extremis, unlikely to survive initial operative repair, and were placed on ECMO prior to the operation. All six patients had immediate respiratory distress after birth with mean Apgars of 2.3 and 3.7. The best pre-ECMO arterial blood gas (postductal) showed mean +/- SEM values of 6.97 +/- 0.1; PO2 = 54.8 +/- 5.9; PCO2 = 79.5 +/- 16.9. Immediately prior to ECMO, the mean +/- SEM ventilatory index (VI = rate x mean airway pressure) was 1,233 +/- 44, with a mean pH of 7.17 +/- 0.05; PO2 = 32 +/- 2.9; PCO2 = 59 +/- 5.3 and a mean AaDO2 of 622 +/- 4.8. The timing of the operative repair averaged 25 hours following initiation of ECMO. Three right-sided and three left-sided hernias were treated. Four were repaired through an abdominal approach, and two via thoracotomy; four required a Gortex patch closure. Postoperative bleeding was not a major problem in these heparinized patients. Four of these six patients survived, and follow-up of 2 months to 3 years shows no significant respiratory compromise.(ABSTRACT TRUNCATED AT 250 WORDS)