What is the next action during cardiopulmonary resuscitation (CPR) with an end-tidal carbon dioxide (EtCO2) level of 12 mmHg, indicating hypocapnia, in a patient in cardiac arrest?

From the Guidelines

I would improve the quality of chest compressions immediately, as an EtCO2 of 12 mmHg indicates inadequate perfusion and poor-quality chest compressions. When EtCO2 is 12 mmHg during CPR, it suggests that cardiac output is inadequate to achieve return of spontaneous circulation (ROSC) 1. To address this, I would ensure proper compression depth (at least 2-2.4 inches or 5-6 cm in adults), appropriate rate (100-120 compressions per minute), complete chest recoil between compressions, and minimal interruptions. I would also consider rotating the compressor to prevent fatigue, as tired rescuers often deliver less effective compressions. EtCO2 monitoring during CPR provides real-time feedback on the effectiveness of resuscitation efforts, with values below 10-20 mmHg suggesting poor cardiac output 1. The goal should be to achieve EtCO2 values of at least 20 mmHg through high-quality CPR. A sudden increase in EtCO2 (typically above 40 mmHg) might indicate return of spontaneous circulation, which would warrant pulse and rhythm checks. Improving compression quality is the most immediate action needed to increase cardiac output and improve the patient's chances of survival.

Some key points to consider when improving chest compression quality include:

• Ensuring proper compression depth and rate
• Allowing for complete chest recoil between compressions
• Minimizing interruptions to chest compressions
• Rotating the compressor to prevent fatigue
• Monitoring EtCO2 trends to guide individual optimization of compression depth and rate, and to detect fatigue in the provider performing compressions 1.

It's also important to note that while the evidence from 1 discusses the importance of adequate ventilation and oxygenation, it does not directly relate to the use of EtCO2 monitoring during CPR, and therefore does not influence the decision to improve chest compression quality in this scenario.

From the Research

Assessment of EtCO2 Levels

• The patient's EtCO2 level is 12 mmHg, which is lower than the average EtCO2 values in patients with return of spontaneous circulation (ROSC) as reported in a study 2.
• According to a study published in 2018 3, ETCO2 levels <10 mmHg are consistently associated with a poor outcome in prolonged out of hospital cardiac arrest, while levels above this threshold have been suggested as a criterion for considering patients for rescue extracorporeal resuscitation.

Next Action

• The team should continue to monitor the patient's EtCO2 levels and adjust CPR techniques as needed to optimize blood flow and organ perfusion.
• The low EtCO2 level may indicate inadequate blood flow, and the team should consider adjusting chest compression depth and ventilation rate to improve EtCO2 levels, as suggested by a study 2.
• The use of epinephrine, which is commonly administered during cardiac arrest, should be considered with caution, as its effectiveness in improving neurologic outcomes is still a topic of debate 4.

Considerations for CPR Quality

• The relationship between EtCO2 and CPR characteristics, such as chest compression depth and ventilation rate, should be taken into account when adjusting CPR techniques 2.
• The team should be aware that EtCO2 levels can be affected by various factors, including the aetiology of cardiac arrest, ventilation patterns, and medications administered during CPR 3.