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Pulmonary hypertension is associated with congenital heart lesions with increased pulmonary blood flow. Acute increases in pulmonary vascular resistance (PVR) occur in the postoperative period after repair of these defects. These increases in PVR can be ablated by inducing an alkalosis with hyperventilation (HV) or bicarbonate therapy. Studies have shown that these patients also respond to inhaled nitric oxide (iNO), but uncertainty exists over the relative merits and undesirable effects of HV and iNO.Alkalosis and iNO are equally effective in reducing PVR and pulmonary artery pressure (PAP) in children with pulmonary hypertension after open heart surgery.Critical care unit of a tertiary care pediatric hospital.Prospective, randomized, crossover design.Twelve children with a mean PAP25 mm Hg at normal pH after biventricular repair of congenital heart disease.Patients were assigned to receive iNO or HV (pH7.5) in random order, and the effect on hemodynamics was measured. Each treatment was administered for 30 mins with a 30-min washout period between treatments. Finally, both treatments were administered together to look for a possible additive effect.Cardiac output and derived hemodynamic parameters using the dye dilution technique. Hyperventilation, achieved by an increase in ventilator rate without a change in mean airway pressure, decreased Pa(CO2) from a mean (SD) of 43.7+/-5.3 to 32.3+/-5.4 mm Hg and increased pH from 7.40+/-0.04 to 7.50+/-0.03. This significantly altered both pulmonary and systemic hemodynamics with a reduction in PAP, PVR, central venous pressure, and cardiac output and an increase in systemic vascular resistance. In comparison, iNO selectively reduced PAP and PVR only. The reduction in PVR was comparable between treatments, although addition of iNO to HV resulted in a small additional reduction in PVR. An additional decrease in PAP was seen when HV was added to iNO, attributable to a reduction in cardiac output rather than a further decrease in PVR.Inhaled NO and HV are both effective at lowering PAP and PVR in children with pulmonary hypertension after repair of congenital heart disease. The selective action of iNO on the pulmonary circulation offers advantages over HV because a decrease in cardiac output and an increase in SVR are undesirable in the postoperative period.

Objective: We sought to assess the effects of four different CO 2 tensions on systemic oxygenation, oxygen consumption, and arterial blood lactate levels early after bidirectional superior cavopulmonary anastomosis. Design: Prospective study. Setting: Quaternary pediatric cardiac critical care unit. Patients: Nine children aged 2-23 months (median, 7 months). Interventions: All patients were sedated, muscle relaxed, and mechanically ventilated. Baseline PaCO 2 was adjusted to 35 mm Hg by changing tidal volume. CO 2 was added via the inlet port of the ventilator to maintain the PaCO 2 at 45 and 55 mm Hg. Measurements were repeated after discontinuing additional CO 2 gas at a PaCO 2 of 40 mm Hg. Arterial blood gases and lactate were measured at each level of PaCO 2 . We measured oxygen consumption continuously by respiratory mass spectrometry. Measurements and Main Results: Mean (95% confidence interval) PaCO 2 increased from 35 (34-36) to 45 (44-46) to 55 (54-56) mm Hg (4.7 [4.5-4.9] to 6 [5.7-6.3] to 7.3 [7.2-7.4] kPa), arterial pH decreased from 7.43 (7.39-7.47) to 7.35 (7.31-7.39) to 7.28 (7.24-7.32). Paoz increased from 36 (32-40) to 44 (40-48) to 50 (45-55) mm Hg (4.8 [4.3-5.3] to 5.9 [5.4-6.4] to 6.7 [6.2-7.2] kPa), and oxygen saturation increased from 72% (67-79%) to 77% (73-81%) to 80% (76-84%). Oxygen consumption decreased significantly, with each increase in PaCO 2 , from 146 (125-167) to 132 (112-152) to 126 (107-145) mL.min -1 .m -2 (p =.0001), and lactate decreased from 1.5 (1-2.0) to 1.2 (0.8-1.6) to 0.8 (0.5-1.1) mmol/L (p

The development of a safe, portable, accurate, and adaptable system to deliver nitric oxide to patients with pulmonary hypertension.A prospective, clinical study.Tertiary care pediatric intensive care unit and cardiac catheterization laboratory.One hundred twenty-three patients (median age 11 months, range 1 day to 72 yrs) with pulmonary hypertension who were administered nitric oxide between November 1991 and July 1993. Ninety-one patients were mechanically ventilated (volume-controlled ventilator, n = 53; pressure-controlled ventilator, n = 5; and a pressure-limited, time-cycled infant ventilator, n = 25). The system was adapted to allow high-frequency oscillator (n = 2) or hand ventilation, and for intraoperative use with an anesthesia machine (n = 6). Thirty-two patients were breathing spontaneously through a mask without assistance.Nitric oxide was delivered at 10 to 80 parts per million (ppm); the dose was adjusted independently of the FIO2 without altering minute ventilation or tidal volume.Nitrogen dioxide was continuously monitored and exceeded 3 ppm in only four patients. Methemoglobin concentrations were5% in all but four patients. Nitric oxide doses remained stable, independent of minute ventilation and could be changed easily and quickly.Inhaled nitric oxide can be administered precisely and reliably through a variety of delivery systems which can be used in patients of any size. Potential toxicity requires careful monitoring and continued improvement on apparatus design.