Chapter 89: Inhaled Nitric Oxide

INDICATION

Clinical Findings

History

This protocol for use of inhaled nitric oxide (iNO) applies to neonates with gestational age 34 weeks or greater on mechanical ventilation with hypoxic respiratory failure. This protocol is not intended for any patient on an active research protocol involving nitric oxide or preterm infants less than 34 weeks’ gestational age.

Physical

Infants will have an elevated oxygenation index (OI) of 25 or greater on 2 arterial blood gases at least 15 minutes apart.

Confirmatory/Baseline Tests

1. 

   • FiO₂: fraction of inspired oxygen (eg, 50% FiO₂ = 0.5)

   • MAP: mean airway pressure, from ventilator

   • PaO₂: partial pressure of arterial oxygen, from arterial blood gas (ABG)

2. Echocardiogram

   1. Evaluate for structural heart disease, which may require surgical intervention.

   2. Evaluate for elevated right-sided heart pressures indicating pulmonary hypertension, as indicated by:

      • Right ventricular or atrial dilation

      • Interventricular septal bowing

      • Elevated right atrial pressure as estimated by tricuspid regurgitation

Differential Diagnosis

1. Meconium aspiration syndrome

2. Pneumonia/sepsis

3. Congenital diaphragmatic hernia

4. Pulmonary hypoplasia

5. Surfactant deficiency or surfactant protein deficiency

6. Congenital alveolar dysplasia (alveolar capillary dysplasia)

Exclusions/Contraindications

1. Neonates with congenital heart disease whose condition would be worsened by decreasing pulmonary vascular resistance (eg, total anomalous pulmonary venous return) are excluded.

2. Inhaled nitric oxide has been approved by the Food and Drug Administration (FDA) for the treatment of hypoxic respiratory failure in neonates born after 33 weeks of gestation. In 2010, a panel from the National Institutes of Health (NIH) developed a consensus statement for the use of nitric oxide in premature infants that discourages its routine use in infants less than 34 weeks of gestation.

PREPARATION

Consent

Consent is not necessary to initiate treatment with iNO.

Monitoring During Treatment

1. Pre- and postductal oxygen saturation monitoring

2. Arterial access for blood pressure and ABG monitoring

3. Measurement of methemoglobin (metHb) and nitrogen dioxide (NO₂) levels

Sedation/Pain Control

Treatment with iNO is not inherently painful, but sedation and pain control can be helpful in minimizing spikes in pulmonary blood pressure that can exacerbate hypoxic respiratory failure.

TREATMENT/PROCEDURE

Initiation

See Figure 89-1 for iNO initiation procedure.

Tests to Follow

Methemoglobin and nitrogen dioxide levels are measured within 3 hours after starting iNO, then every 12 hours if the dose is greater than 20 ...