Incidence of hyperoxia and factors associated with cerebral oxygenation during cardiopulmonary resuscitation

Abstract

Background: High oxygen levels may worsen cardiac arrest reperfusion injury. We determined the incidence of hyperoxia during and immediately after successful cardiopulmonary resuscitation and identified factors associated with intra-arrest cerebral oxygenation measured with near-infrared spectroscopy (NIRS).Methods: A prospective observational study of out-of-hospital cardiac arrest patients treated by a physician-staed helicopter unit. Collected data included intra-arrest brain regional oxygen saturation (rSO 2 ) with NIRS, invasive blood pressures, end-tidal CO 2 (etCO 2 ) and arterial blood gas samples. Moderate and severe hyperoxia were defined as arterial oxygen partial pressure (paO 2 ) 20.0-39.9 and !40 kPa, respectively. Intra-arrest factors correlated with the NIRS value, rSO 2, were assessed with the Spearman's correlation test.Results: Of 80 recruited patients, 73 (91%) patients had rSO 2 recorded during CPR, and 46 had an intra-arrest paO 2 analysed. ROSC was achieved in 28 patients, of whom 20 had paO 2 analysed. Moderate hyperoxia was seen in one patient during CPR and in four patients (20%, 95% CI 7-42%) after ROSC. None had severe hyperoxia during CPR, and one patient (5%, 95% 0-25%) immediately after ROSC. The rSO 2 during CPR was correlated with intra-arrest systolic (r = 0.28, p < 0.001) and diastolic blood pressure (p = 0.32, p < 0.001) but not with paO 2 (r = 0.13, p = 0.41), paCO 2 (r = 0.18, p = 0.22) or etCO 2 (r = 0.008, p = 0.9). Conclusion:Hyperoxia during or immediately after CPR is rare in patients treated by physician-staed helicopter units. Cerebral oxygenation during CPR appears more dependent, albeit weakly, on hemodynamics than arterial oxygen concentration.

Reply to ‘Monitoring of cerebral oxygenation during cardiopulmonary resuscitation may dramatically reduce the incidence of severe hyperoxia’

“…To the Editor, We thank Sanfilippo and colleagues for their interest and viewpoints on our recent study assessing the prevalence of hyperoxia and factors associated with cerebral oxygenation during cardiopulmonary resuscitation (CPR). 1 We agree that the prevalence of hyperoxia was lower in our study sample than reported in some previous studies. [2][3][4] Sanfilippo and colleagues suggest that this could be related to the use of near infrared spectroscopy (NIRS) as a part of the study protocol.…”

Hyperoxemia after reperfusion in cardiac arrest patients: a potential dose–response association with 30-day survival

“…Following cardiac arrest, the cerebral tissue oxygen tension (PbtO 2 ) drops within minutes to almost zero [ 32 , 33 ]. By administration of a high fraction of inspired oxygen (FiO 2 ) during CPR, the PbtO 2 during optimal experimental conditions, can be restored close to pre-arrest levels [ 32 – 34 ]. Furthermore, observational studies have demonstrated an association between higher PaO 2 during CPR and greater probability to obtain ROSC [ 35 , 36 ].…”

Post-Cardiac Arrest Syndrome

“…During cardiopulmonary resuscitation, before the return of spontaneous circulation, it is conventional to ventilate the lungs with 100% oxygen. In 1 observational study, arterial blood gas analysis during OHCA demonstrated mild hyperoxia in just 1 of 40 patients before ROSC and in 4 of 20 patients immediately after ROSC 8…”

“…In 1 observational study, arterial blood gas analysis during OHCA demonstrated mild hyperoxia in just 1 of 40 patients before ROSC and in 4 of 20 patients immediately after ROSC. 8 In the EXACT (Reduction of Oxygen After Cardiac Arrest) trial, 428 unconscious OHCA patients were randomized by paramedics to an intervention arm with target blood oxygen saturation of 90% to 94% or standard care of 98-100%. 9 In the intervention group, 38.3% survived to hospital discharge (the primary outcome) compared with 47.9% in the standard care group (difference, −9.6%; 95% confidence interval (CI), −18.9% to −0.2%; odds ratio (OR), 0.68; 95% CI, 0.46 to 1.00; P = 0.05).…”