Clinical characteristics and factors associated with term and late preterm infants that do not respond to inhaled nitric oxide (iNO).
OBJECTIVE
Inhaled nitric oxide (iNO) is used to treat neonates with hypoxic respiratory failure (HRF). The aim of this study was to determine clinical characteristics and factors associated with non-response to iNO therapy that may assist in clinical management and weaning strategies.


METHODS
Retrospective chart review. The study cohort included gestational age ≥34 weeks' infants with acute HRF who received iNO within 7 days of birth. Subjects were stratified as responders or non-responders to iNO. Non-responders were defined as infants with failure to improve their PaO2 >20 mm Hg within 6 h of iNO initiation, need for extracorporeal membrane oxygenation (ECMO), or mortality. Clinical and laboratory characteristics were then compared between groups.


RESULTS
Forty four subjects were included. There were 31 responders and 13 non-responders to iNO therapy. Regression analysis showed significant correlation between a non-response to iNO therapy and changes in PaO2 and pH levels. We found for every 10 mm Hg decrease in PaO2 immediate post-iNO therapy there is a 17.5% decrease in the likelihood of responding to iNO (odds ratio [OR] 0.98, P=0.012). Similarly, for every 0.15 point decrease in pH, there is a 16.3% increased chance of not responding to iNO therapy (OR 1.16, P=0.002). The need for pressor support prior to iNO initiation was also found to be associated with a non-response (OR 2. 94, P=0.034).


CONCLUSIONS
Hypotension requiring treatment with pressors at the time of iNO therapy, as well as changes in pH and PaO2 after iNO initiation can be used as early clinical predictors to identify patients quickly who may be iNO non-responders.
Alexandra Almanzar
AA
Morel
Evan
E
Shreck
Pradeep V
PV
Mally
Yang
Y
Kim
Sean M
SM
Bailey
Elena V
EV
Wachtel
D000280:Administration, Inhalation; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D015199:Extracorporeal Membrane Oxygenation; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D016015:Logistic Models; D009569:Nitric Oxide / Q000627:therapeutic use*; D011379:Prognosis; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality / Q000628:therapy; D012189:Retrospective Studies; D017211:Treatment Failure
D001993:Bronchodilator Agents; D009569:Nitric Oxide