Critically evaluate the role of nitric oxide in the management of the critically ill patient.
Nitric oxide has many potential benefits in the critically ill. In particular, selective delivery via the inhalational route allows local vasodilatation (potentially improving ventilation:perfusion matching, and reducing pulmonary arterial hypertension), as well as providing some immunomodulating effects (inhibiting neutrophil adhesion and platelet aggregation). Despite a number of prospective randomised trials (in acute lung injury and ARDS) demonstrating some short-term oxygenation benefits (up to 72 hours), in adult patients there have been no improvements in longer-term outcomes (such as weaning from ventilation or mortality). Similarly, physiological improvements in pulmonary hypertension in various clinical scenarios have been demonstrated (e.g. primary pulmonary hypertension, heart transplantation) but no longer-term benefits have been demonstrated. Use of NO requires complex equipment, including monitoring for NO and nitrogen dioxide concentrations. Administration of NO has not been without its own potential adverse effects: Methaemoglobinaemia, prolonged bleeding time, and reports of increased renal failure and nosocomial infections. (Adhikari N. JAMA 2004; 291:1629-31; Sokol J et al. Inhaled nitric oxide for acute hypoxemic respiratory failure in children and adults: A meta-analysis. Anesth Analg 2003;
97:989-98 & Sokol J et al. Inhaled nitric oxide for acute hypoxemic respiratory failure in children and adults (Cochrane Review). In: The Cochrane Library, Issue 1, 2004.)
Nitric oxide is discussed elsewhere. It has fallen out of favour, but during 2004 it must have seemed like panacea. The pharmacology of nitric oxide is respectfully treated elsewhere.
Arguments for and against the use of nitric oxide:
Ikaria, the only company which produces this stuff in Australia, has an excellent product information pamphlet.