Diagnostic Accuracy of the Carbon Dioxide Gap (ΔCO2) in Predicting the Return of Spontaneous Circulation: A Prospective Single Center Study

Öz

Aim: The carbon dioxide gap or ΔCO2 is the difference between the partial pressure of carbon dioxide (pCO2 ) and end-tidal carbon dioxide (ETCO2 ), which should normally not exceed 3-5mmHg. In critically ill patients ΔCO2 increases as a result of decreased cardiac output and pulmonary blood flow compromise. The primary outcome of this study is to examine the diagnostic accuracy of ΔCO2 in predicting the return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) patients. Material and Methods: Non-traumatic OHCA patients over 18 years of age were included in this prospective observational study. ETCO2 values were recorded 1 minute after the intubation and arterial blood gas samples were acquired simutaneously. The difference between the initial ΔCO2 medians of the ROSC+ and ROSC- patient groups were analyzed and the diagnostic test performance in predicting ROSC of ΔCO2 was calculated. A regression model was performed to accurately predict ROSC in OHCA patients. Results: A total of 46 patients were included to the inal analysis. The ΔCO2 median of the ROSC+ group was significantly lower than the ROSC- group (p=0.026, 95%CI:-31 to-3). Area under the curve was calculated as 0.694 (95%CI: 0.532 to 0.855), sensitivity 76.19% (95%CI:52.83 to 91.78%), specificity 76% (95%CI:54.87 to 90.64), and accuracy 76.09% (95%CI:61.23% to87.41%) for the optimal cut-off value (51.4 mmHg). The regression model consists of age, initial ETCO2 , and initial cardiac rhythm showed good discrimination in predicting ROSC (AUC=0.846, 95%CI=0.735 to 0.956, p<0.001). Conclusion: A statistically significant difference was found between the initial ΔCO2 medians in ROSC+ and ROSC- OHCA patients. However, the performance of this test indicates that ΔCO2 cannot be used as a stand-alone test to predict ROSC.

Anahtar Kelimeler

• ΔCO2
• delta carbon dioxide
• carbon dioxide gap
• cardiopulmonary resuscitation
• return of spontaneous circulation
• out of hospital cardiac arrest

Spontan Dolaşımın Geri Dönüşünü Tahmin Etmede Delta Karbondioksitin (ΔCO2) Tanısal Değerinin İncelenmesi: Prospektif Tek Merkezli Çalışma

Öz

Amaç: Delta karbondioksit veya ΔCO2, normalde 3-5 mmHg'yi geçmemesi gereken parsiyel karbondioksit (pCO2) basıncı ile end-tidal karbondioksit (ETCO2) arasındaki farktır. Kritik hastalarda ΔCO2, kalp debisinin azalması ve pulmoner kan akışındaki bozulmanın bir sonucu olarak yükselir. Bu çalışmanın birincil sonlanımı, hastane dışı kardiyak arrest (HDKA) hastalarında spontan dolaşımın geri dönüşünü (SDGD) öngörmede ΔCO2 'nin tanısal değerini incelemektir. Gereç ve Yöntemler: Bu prospektif gözlemsel çalışmaya 18 yaşın üzerindeki travmatik olmayan HDKA hastaları dahil edildi. ETCO2 değerleri entübasyondan 1 dakika sonra kaydedildi ve hastalardan eş zamanlı olarak arter kan gazı örneği alındı. SDGD olan ve SDGD olmayan hasta gruplarının ilk ΔCO2 medyanları arasındaki fark analiz edildi ve ΔCO2'nin SDGD'yi öngörmedeki tanısal performansı hesaplandı. HDKA hastalarında SDGD'yi doğru bir şekilde tahmin etmek için bir regresyon modeli uygulandı. Bulgular: Son analize toplam 46 hasta dahil edildi. SDGD+ grubunun ΔCO2 medyanı, SDGD- grubundan anlamlı olarak düşüktü (p=0,026, %95GA: -31 - -3). Optimum eşikdeğeri için (51,4 mmHg) eğri altındaki alan 0,694 (%95GA: 0,532 - 0,855), duyarlılık %76,19 (%95GA:52,83 - %91,78), özgüllük %76 (%95GA:54,87 - 90,64) ve doğruluk %76,09 (%95GA:%61,23 - %87,41) olarak hesaplandı. Yaş, ilk ETCO2 ve ilk kardiyak ritminden oluşan regresyon modeli, SDGD'yi öngörmede iyi bir performans gösterdi (EAA=0,846, %95CI=0,735 - 0,956, p<0,001). Sonuç: SDGD+ ve SDGD- HDKA hastalarının ilk ΔCO2 medyanları arasında istatistiksel olarak anlamlı bir fark bulundu. Ancak bu testin performansı, ΔCO2'nin SDGD'yi tahmin etmek için tek başına bir test olarak kullanılamayacağını göstermektedir.

Anahtar Kelimeler

• ΔCO2
• delta karbondioksit
• karbondioksit gap
• kardiyopulmoner resüsitasyon
• spontan dolaşımın geri dönüşü
• hastane dışı kardiyak arrest

Kaynakça

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