Austin Health

Title
Cerebral oxygenation in mechanically ventilated early cardiac arrest survivors: The impact of hypercapnia
Publication Date
2016-05
Author(s)
Eastwood, Glenn M
Tanaka, Aiko
Bellomo, Rinaldo
Subject
Cardiac arrest
Cerebral oxygenation
Hypercapnia
Mechanical ventilation
Normocapnia
Type of document
Journal Article
DOI
10.1016/j.resuscitation.2016.02.009
Abstract
BACKGROUND:
Optimal cerebral oxygenation is considered fundamental to cerebral protection in cardiac arrest (CA) patients. Hypercapnia increases cerebral blood flow and may also improve cerebral oxygenation. It is uncertain, however, whether this effect occurs in mechanically ventilated early survivors of CA.
METHODS:
We enrolled mechanically ventilated resuscitated patients within 36h of their cardiac arrest. We performed a prospective double cross-over physiological study comparing the impact of normocapnia (PaCO2 35-45mmHg) vs. mild hypercapnia (PaCO2 45-55mmHg) on regional cerebral tissue oxygen saturation (SctO2) assessed by near infrared spectroscopy (NIRS).
RESULTS:
We studied seven adult CA patients with a median time to return of spontaneous circulation of 28min at a median of 26h and 30min after CA. During normocapnia (median EtCO2 of 32mmHg [30-41mmHg] and PaCO2 of 37mmHg [32-45mmHg]) the median NIRS-derived left frontal SctO2 was 61% [52-65%] and the right frontal SctO2 was 61% [54-68%]. However, during mild hypercapnia (median EtCO2 of 49mmHg [40-57mmHg] and PaCO2 of 52mmHg [43-55mmHg) the median left frontal SctO2 increased to 69% [59-78%] and the right frontal SctO2 increased to 73% [61-76%])(p=0.001, for all comparisons).
CONCLUSION:
During the early post-resuscitation period, in mechanically ventilated CA patients, mild hypercapnia increases cerebral oxygenation as assessed by NIRS. Further investigations of the effect of prolonged mild hypercapnia on cerebral oxygenation and patient outcomes appear justified.
Link
Citation
Resuscitation 2016; 102: 11-16

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