Introduction and Aim: The selection of prior treatment in situations of hypoxic and/or hypercarbic respiratory failure in critically ill patients to avoid non-invasive positive pressure ventilation (NIMV) endotracheal intubation. The Average Volume Assured Pressure Support mode (AVAPS), which ensures both volume and pressure support to the patient at the same time, is a new NIMV mode that rapidly corrects the state of consciousness and the blood gas parameters in patients with hypercarbic respiratory failure. In our study, we compared the effects of AVAPS and BPAP ST/T modes on the carbon dioxide level, need for additional treatment, and duration of hospital stay of patients who were referred to emergency department and for whom a decision was taken for NIMV. Materials and Methods: In this prospective single-blind, randomized controlled trial, NIMV was administered to patients with hypercapnic respiratory failure who were referred to our emergency department between 22.10.2016-01.06.2017 and for whom NIMV was planned, with randomization and after being separated into AVAPS and ST/T groups. Patients' vital parameters (blood pressure, heart rate, sat O₂, respiratory rate), Glasgow Coma Scale (GCS), arterial blood gas data (PaCO₂, PaO₂, pH, SatO₂) were followed. There was a significant difference in the success of treatment between the two groups.Results: Of the 80 patients included in the study, 33 were in the ST/T group and 47 were in the AVAPS group. A significant decrease in pH and PaCO2 values was observed in the ST/T group (p=0.006 and p=0.005 respectively). There were no significant changes in vital signs. When the pH and PaCO₂ values were compared in the AVAPS group, there was a significant difference between all measurements (p <0.001). In the AVAPS group, there was a significant decrease in the systolic and diastolic blood pressures (p=0.009 and p<0.001 respectively). No significant difference could be found between the two groups in the changes of the PaCO2 and pH values over time (p=0.141 and p=0.271 respectively) in recurrent measurements. No statistically significant differences were found between the groups when the periods of stay in the emergency ward and hospital were compared (p=0.800 and p=0.815 respectively). Only one patient (1,25%) was intubated in the first 24 hours. NIMV treatment was terminated in 21 patients (26.3%) due to patient incompatibility and 51 patients (63.8%) because of no need NIMV.Conclusion: In our study, we observed that in the AVAPS group, blood gas parameters improved faster than ST/T group. However, we did not find any significant difference between the two groups when following the clinical findings and laboratory parameters. AVAPS is a NIMV mode that is as effective as BPAP S/T in hypercapnic respiratory failure in the emergency department.Key Words: Hypercapnia, Respiratory failure, NIMV, BPAP, ST/T mode, AVAPS.

Gereç ve Yöntem: Bu prospektif tek kör randomize kontrollü çalışmada 22.10.2016-01.06.2017 tarihleri arasında acil servisimize başvuran hiperkarbik solunum yetmezliği olan ve NIMV planlanan hastalar, randomizasyon ile AVAPS ve ST/T gruplarına ayrıldıktan sonra NIMV uygulandı. Hastaların vital parametreleri (kan basıncı, kalp hızı, sat O₂, solunum sayısı), Glasgow Koma Skoru(GKS), arteryal kan gazı verileri (PaCO₂, PaO₂, pH, SatO₂) takip edildi. Her iki grup arasında tedavi başarısında anlamlı farklılık olup olmadığı karşılaştırıldı.Bulgular: Çalışmaya dahil edilen 80 hastanın 33'ü ST/T, 43'ü AVAPS grubunda idi. ST/T grubunda pH ve PaCO2 değerlerinde anlamlı düşme olduğu görüldü (sırasıyla p=0.006 ve p=0.005). Vital bulgularda herhangi bir anlamlı değişiklik saptanmadı. AVAPS grubunda pH ve PaCO₂ değerleri karşılaştırıldığında tüm ölçümler arasında anlamlı fark saptandı (p<0,001). AVAPS grubunda sistolik ve diyastolik kan basıncında anlamlı düşme olduğu (sırasıyla p<0,001 ve p=0,002) görüldü. Her iki grupta da tekrarlayan ölçümlerde PaCO2 ve pH değerlerinin zaman içerisinde değişimlerinde iki grup arasında anlamlı fark bulunmadı (sırasıyla p=0.141 ve p=0.271). Acil serviste ve hastanede kalış süreleri karşılaştırıldığında gruplar arasında anlamlı fark saptanmadı (sırasıyla p=0,800 ve p=0,815). Sadece 1 hasta (%1,25) ilk 24 saatte entübe edildi. 51 hastada (%63,8) NIMV ihtiyacı kalmadığı için, 21 hastada (%26,3) ise hasta uyumsuzluğu nedeniyle NIMV sonlandırıldı. Sonuç: Çalışmamızda AVAPS grubunda ST/T grubuna göre kan gazı parametrelerinde daha hızlı düzelme olduğunu gözlemledik. Ancak laboratuvar ve klinik parametrelerinin değişiminde her iki grup arasında anlamlı fark saptamadık. AVAPS, acil serviste hiperkarbik solunum yetmezliğinde BPAP S/T kadar etkili bir NIMV modudur.Anahtar Kelimeler: Hiperkarbi, Solunum yetmezliği, NIMV, BPAP, ST/T mod, AVAPS.