Hyperoxia in the intensive care unit and outcome after out-of-hospital ventricular fibrillation cardiac arrest
Laboratory and clinical studies have suggested that hyperoxia early after resuscitation from cardiac arrest may increase neurological injury and worsen outcome. Previous clinical studies have been small or have not included relevant prehospital data. We aimed to determine in a larger cohort of patients whether hyperoxia in the intensive care unit in patients admitted after out-ofhospital cardiac arrest (OHCA) was associated with increased mortality rate after correction for prehospital variables.
Data from the Victorian Ambulance Cardiac Arrest Registry (VACAR) of patients transported to hospital after resuscitation from OHCA and an initial cardiac rhythm of ventricular fibrillation between January 2007 and December 2011 were linked to the Australian and New Zealand Intensive Care Society Adult Patient Database (ANZICS-APD). Patients were allocated into three groups (hypoxia [PaO2<60mmHg], normoxia [PaO2,60-299mmHg] or hyperoxia [PaO2≥300mmHg]) according to their most abnormal PaO2 level in the first 24 hours of ICU stay. The relationship between PaO2 and hospital mortality was investigated using multivariate logistic regression analysis to adjust for confounding prehospital and ICU factors.
There were 957 patients identified on the VACAR database who met inclusion criteria. Of these, 584 (61%) were matched to the ANZICS-APD and had hospital mortality and oxygen data available. The unadjusted hospital mortality was 51% in the hypoxia patients, 41% in the normoxia patients and 47% in the hyperoxia patients (P=0.28). After adjustment for cardiopulmonary resuscitation by a bystander, patient age and cardiac arrest duration, hyperoxia in the ICU was not associated with increased hospital mortality (OR, 1.2; 95% CI, 0.51-2.82; P=0.83).
Hyperoxia within the first 24 hours was not associated with increased hospital mortality in patients admitted to ICU following out-of-hospital ventricular fibrillation cardiac arrest.
Available from: Elisa Damiani
- "Normoxia APACHE III risk of death (O 2 component removed), treatment limitation, year of admission, lowest glucose in the first 24 h, hospital admission from home, hypoxia/poor O 2 exchange Ihle et al. 2013  "
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ABSTRACT: IntroductionThe safety of arterial hyperoxia is under increasing scrutiny. We performed a systematic review of the literature to determine whether any association exists between arterial hyperoxia and mortality in critically ill patient subsets.Methods
Medline, Thomson Reuters Web of Science and Scopus databases were searched from inception to June 2014. Observational or interventional studies evaluating the relationship between hyperoxia (defined as a supranormal arterial O2 tension) and mortality in adult intensive care unit (ICU) patients were included. Studies primarily involving patients with exacerbations of chronic pulmonary disease, acute lung injury and perioperative administration were excluded. Adjusted odds ratio (OR) of patients exposed versus those non-exposed to hyperoxia were extracted, if available. Alternatively, unadjusted outcome data were recorded. Data on patients, study characteristics and the criteria used for defining hyperoxia exposure were also extracted. Random-effects models were used for quantitative synthesis of the data, with a primary outcome of hospital mortality.ResultsIn total 17 studies (16 observational, 1 prospective before-after) were identified in different patient categories: mechanically ventilated ICU (number of studies (k)¿=¿4, number of participants (n)¿=¿189,143), post-cardiac arrest (k¿=¿6, n¿=¿19,144), stroke (k¿=¿2, n¿=¿5,537), and traumatic brain injury (k¿=¿5, n¿=¿7,488). Different criteria were used to define hyperoxia in terms of PaO2 value (first, highest, worst, mean), time of assessment and pre-determined cut-offs. Data from studies on ICU patients were not pooled because of extreme heterogeneity (Inconsistency (I2) 96.73%). Hyperoxia was associated with increased mortality in post-cardiac arrest patients (OR¿=¿1.42 (1.04 to 1.92) I2 67.73%) stroke (OR¿=¿1.23 (1.06 to 1.43) I2 0%) and traumatic brain injury (OR¿=¿1.41 (1.03 to 1.94) I2 64.54%). However, these results are limited by significant heterogeneity between studies.Conclusions
Hyperoxia may be associated with increased mortality in patients with stroke, traumatic brain injury and those resuscitated from cardiac arrest. However, these results are limited by the high heterogeneity of the included studies.
Critical care (London, England) 12/2014; 18(6):711. DOI:10.1186/s13054-014-0711-x · 4.48 Impact Factor
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ABSTRACT: Studies investigating the relationship between blood gas tension and outcome in cardiac arrest survivors have reported conflicting results. This might have resulted from the use of a blood gas value at a single time point and the difference in the proportion of patients treated with therapeutic hypothermia (TH). We investigated the association of the mean blood gas tensions calculated from blood gas values obtained between restoration of spontaneous circulation and end of TH with the outcome in cardiac arrest patients treated with TH.
This was a retrospective observational study including 213 adult cardiac arrest patients. The cohort was divided into four categories based on the distribution of the mean Pao2 data using quartiles as cut-off values between categories. According to the mean Paco2, the cohort was divided into hypocarbia, normocarbia, and hypercarbia. The primary outcome was in-hospital mortality.
In multivariate analysis, the mean Pao2 quartile was not associated with in-hospital mortality, but hypocarbia was significantly associated with increased risk of in-hospital mortality (odds ratio 2.522; 95% confidence interval 1.184-5.372; P = .016). We found a V-shaped independent association between the mean Pao2 and poor neurologic outcome at hospital discharge, with the risk of poor neurologic outcome increasing with a descending and ascending Pao2 ranges.
Mean Pao2 had no independent association with in-hospital mortality whereas hypocarbia was independently associated with in-hospital mortality. We also found a V-shaped independent association between the mean Pao2 and poor neurologic outcome at hospital discharge.
The American journal of emergency medicine 10/2013; 32(1). DOI:10.1016/j.ajem.2013.09.044 · 1.27 Impact Factor
Journal of critical care 10/2013; 29(1). DOI:10.1016/j.jcrc.2013.10.002 · 2.00 Impact Factor
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