INHALED NITRIC OXIDE

Nitric Oxide, iNO

Reviewed by Clinical Practice Committee
March 2018
Administration Newborn Drug Protocol Index Newborn Services Home Page

Nitric oxide (iNO) is a potent vasodilator used to treat pulmonary hypertension. It is a gas that is given into the ventilator circuit; it is inactivated instantly in blood, by reacting with haemoglobin. Therefore, it produces rapid and localized effects on the pulmonary vasculature but no action on the systemic vasculature or systemic blood pressure.

Indications

Contraindications and Precautions

Dose and Administration

  1. Start on 20 ppm. Doses above 20 ppm are not indicated as there would be little if any additional benefit plus risk of toxicity increases.
  2. Evaluate for response to treatment in 30-60 minutes. Examples of complete (and partial) responses to iNO include:

Weaning iNO and FiO2

There is little evidence to guide the best method of weaning iNO. If a positive response is seen after iNO initiation, then iNO dose should continue at 20 ppm while the bedside nurse weans FiO2.


“Rebound” pulmonary hypertension occurs when FiO2 must be increased by 0.20 or more to maintain sSaturations>95%, following an iNO wean. If this occurs, halt weaning or return to the previous therapeutic iNO dose.

Equipment

  1. Cylinder has 880 parts per million (ppm) in nitrogen
  2. Add to ventilator circuit between humidifier and baby.
  3. Click here to open the nitric oxide calculator
    1. 100 ml/min added to 10 litres/min ventilator gas flow = 8.7 ppm
    2. 200 ml/min added to 10 litres/min ventilator gas flow = 17.4 ppm

Clinical Pharmacology

Nitric oxide is endothelial derived relaxing factor (EDRF). It is produced in the endothelium of blood vessels and diffuses out of the cells. It then enters vascular smooth muscle cells and activates guanalate cyclase which forms cyclic guanosine monophosphate (cGMP). This is a smooth muscle relaxer. cGMP is inactivated by cGMP phosphodiesterase. The half life of NO is 3-6 seconds.

iNO is bound to haemoglobin and inactivated to nitosylhaemoglobins and methaemoglobin.

Possible Adverse Effects

Related Protocols:

References:

1 Barrington KJ, Finer N, Pennaforte T. Inhaled nitric oxide for respiratory failure in preterm infants. Cochrane Database of Systematic Reviews 2017, Issue 1. Art. No.: CD000509. DOI: 10.1002/14651858.CD000509.pub5
2 Barrington KJ, Finer N, Pennaforte T, Altit G. Nitric oxide for respiratory failure in infants born at or near term. Cochrane Database of Systematic Reviews 2017, Issue 1. Art. No.: CD000399. DOI: 10.1002/14651858.CD000399.pub3
3  Baczynski M, Ginty S, Weisz DE, et al. Short-term and long-term outcomes of preterm neonates with acute severe pulmonary hypertension following rescue treatment with inhaled nitric oxide. Arch Dis Child Fetal Neonatal Ed 2017;102:F508-F514. Doi:10.1136/ archdischild-2016-312409.