What marker indicates a positive outcome in an intubated patient with Ventricular Fibrillation (VF) or Asystole (AESP) and ongoing Cardiopulmonary Resuscitation (CPR)?

From the Guidelines

End-tidal carbon dioxide (ETCO2) levels above 10-20 mmHg during CPR are the most reliable marker indicating a positive outcome for intubated patients with ventricular fibrillation (VF) or asystole/pulseless electrical activity (AESP).

Importance of ETCO2 Monitoring

The use of ETCO2 monitoring is crucial in guiding resuscitation efforts, as it directly reflects pulmonary blood flow and indirectly indicates cardiac output during chest compressions 1.

Key Findings

• An ETCO2 value greater than 10 mmHg after 20 minutes of resuscitation efforts suggests potential for return of spontaneous circulation (ROSC), while values above 20 mmHg are even more strongly associated with survival.
• When ETCO2 suddenly increases (often to 35-40 mmHg or higher), it typically signals ROSC has occurred, even before a pulse can be detected.
• Low or declining ETCO2 values despite high-quality CPR suggest poor tissue perfusion and decreased likelihood of successful resuscitation.

Clinical Application

ETCO2 monitoring should be implemented immediately after intubation and continuously assessed throughout resuscitation.

• Other positive prognostic indicators include shockable rhythms (VF is better than AESP), shorter downtime before CPR initiation, and younger patient age, but ETCO2 remains the most objective and immediately available physiologic parameter to guide resuscitation efforts.
• The 2015 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations also highlights the importance of monitoring physiological parameters during CPR, including ETCO2 1.

Best Practice

Healthcare providers should be trained in delivering effective oxygenation and ventilation with a bag and mask, as well as in the insertion of advanced airways, such as endotracheal tubes or supraglottic airways 1.

• Continuous waveform capnography is recommended in addition to clinical assessment as the most reliable method of confirming and monitoring correct placement of an endotracheal tube.
• The use of capnography to confirm and monitor correct placement of supraglottic airways has not been studied, and its utility will depend on airway design.

From the Research

Positive Outcome Indicators in Intubated Patients with VF or AESP and Ongoing CPR

• The most important prognostic indicators of a favorable outcome in patients with return of spontaneous circulation (ROSC) from cardiopulmonary arrest are age, time from collapse to ROSC (TROSC), and presence of pre-hospital ROSC (PROSC) for VF, and age, TROSC, PROSC, and conversion to VF for PEA/asystole 2.
• A model based on four selected indicators (age, TROSC, PROSC, and conversion to VF) showed a high predictive value for favorable outcome in OHCA patients with ROSC 2.
• Strong predictors for survival and favorable neurological outcome in cardiac arrest patients are ventricular tachycardia/ventricular fibrillation (VT/VF) as initial rhythm, cardiac etiology, and time to ROSC < 20 minutes 3.
• Patients with the combination of VT/VF and ROSC < 20 minutes have the best chance of both survival and a favorable neurological outcome 3.
• A treatment bundle including extracorporeal cardiopulmonary resuscitation (ECPR), therapeutic hypothermia, and intra-aortic balloon pump (IABP) is associated with improved neurological outcome at 1 and 6 months after OHCA in patients with VF/VT on the initial ECG 4.
• The use of advanced perfusion and reperfusion life support strategies, such as ECPR and coronary angiography with primary coronary intervention (PCI), can lead to a high functionally favorable survival rate with few complications in patients with refractory VF/VT 5.