Oxigeno

Pediatric Cardiology
Relationship Between Arterial Partial Oxygen Pressure
After Resuscitation From Cardiac Arrest and Mortality
in Children
Lee P. Ferguson, MBChB; Andrew Durward, FCP; Shane M. Tibby, MSc, MBChB
Background—Observational studies in adults have shown a worse outcome associated with hyperoxia after resuscitation
from cardiac arrest. Extrapolating from adult data, currentpediatric resuscitation guidelines recommend avoiding
hyperoxia. We investigated the relationship between arterial partial oxygen pressure and survival in patients admitted
to the pediatric intensive care unit (PICU) after cardiac arrest.
Methods and Results—We conducted a retrospective cohort study using the Pediatric Intensive Care Audit Network
(PICANet) database between 2003 and 2010 (n 122521). Patients aged 16 years with documented cardiac arrest
preceding PICU admission and arterial blood gas analysis taken within 1 hour of PICU admission were included. The
primary outcome measure was death within the PICU. The relationship between postarrest oxygen status and outcome
was modeled with logistic regression, with nonlinearities explored via multivariable fractional polynomials.Covariates
included age, sex, ethnicity, congenital heart disease, out-of-hospital arrest, year, Pediatric Index of Mortality-2 (PIM2)
mortality risk, and organ supportive therapies. Of 1875 patients, 735 (39%) died in PICU. Based on the first arterial gas,
207 patients (11%) had hyperoxia (PaO2 300 mm Hg) and 448 (24%) had hypoxia (PaO2 60 mm Hg). We found a
significant nonlinear relationshipbetween PaO2 and PICU mortality. After covariate adjustment, risk of death increased
sharply with increasing hypoxia (odds ratio, 1.92; 95% confidence interval, 1.80 –2.21 at PaO2 of 23 mm Hg). There was
also an association with increasing hyperoxia, although not as dramatic as that for hypoxia (odds ratio, 1.25; 95%
confidence interval, 1.17–1.37 at 600 mm Hg). We observed an increasingmortality risk with advancing age, which was
more pronounced in the presence of congenital heart disease.
Conclusions—Both severe hypoxia and, to a lesser extent, hyperoxia are associated with an increased risk of death after
PICU admission after cardiac arrest. (Circulation. 2012;126:335-342.)
Key Words: cardiac arrest

cardiopulmonary resuscitation

S

urvival to hospital discharge afterin-hospital and out-ofhospital cardiac arrest in children remains low.1–3 Even
with achievement of return of circulation, many children die
in subsequent days, with death usually attributed to neurological injury or cardiovascular dysfunction.1 Recent research
has focused on therapeutic strategies to attenuate the post–
cardiac arrest syndrome that accompanies postischemic reperfusion.4 Evidencefrom animal models indicates postischemic hyperoxia promotes free radical– generated injury5 and
that oxidative stress contributes to both neurological injury6
and cardiac dysfunction.7 In addition, hyperoxia has also been
shown to decrease cardiac output8 and reduce regional oxygen delivery to both cerebral and coronary vascular beds.9,10

heart arrest

oxygen

pediatrics

ings.11,12 Ina multicenter retrospective study of 6326 adults
admitted to an intensive care unit (ICU) after nontraumatic
cardiac arrest, the Emergency Medicine Shock Research
Network (EMShockNet) investigators found that exposure to
arterial hyperoxia after resuscitation, based on the first
arterial blood gas after ICU admission, carried an independent risk of in-hospital death. In secondary analysis ofthis
data set, a dose-dependent relationship in the association
between supranormal oxygen tension and relative risk of
in-hospital mortality was observed.13 Bellomo et al12 repeated
the study using a larger data set of 12 108 patients from the
Australian and New Zealand Adult Patient Database. Using
the lowest recorded arterial PaO2 during the first 24 hours of
ICU admission but...