Ridgeview Medical Center

Introduction: Multiple clinical trials have failed to show significant differences in survival between use of endotracheal intubation (ETI) and supraglottic airway devices (SGA) in patients with out-of-hospital cardiac arrest (OHCA). However, treatment in these trials was limited to standard ACLS, which favors short duration of CPR. We sought to compare the physiological effect of ETI versus SGA use in patients treated with prolonged CPR and extracorporeal pulmonary resuscitation (ECPR) for refractory ventricular fibrillation/ventricular tachycardia (VT/VF) by the Minnesota Mobile Resuscitation Consortium (MMRC). Methods: Consecutive refractory VT/VF OHCA patients transported by the MMRC to the University of Minnesota for ECPR between 2015 and 2021 were included in this retrospective analysis. Patients were considered ineligible for ECPR if they failed specific arterial blood gas metabolic criteria (lactic acid >18 mmol/L, PaO2 <50 mmHg, and ETCO2 <10 mmHg). Metabolic parameters at presentation and survival were compared between patients receiving ETI and SGA. Results: Among 260 patients (58.0±11.8 years), 46.5% received ETI and 53.5% received SGA. During the index hospitalization, 78/260 (30%) achieved neurologically favorable survival. Compared to those receiving ETI, patients receiving SGA had lower PaO2 (116.8±118.7 versus 135.8±128.3 mmHg, p=0.03), higher PaCO2 (69.7±28.9 versus 60.7±25.6 mmHg, p=0.01), and lower pH (7.00±0.19 versus 7.06±0.21, p=0.008). Significantly more patients who received SGA had PaO2 <50mmHg (29.1% versus 16.9%, respectively; p=0.02) and ≥1 ECPR exclusion criteria (33.1% versus 20.7%, respectively; p=0.03). Among patients excluded for PaO2 <50 mmHg, the presenting PaO2 was 35.5±11.0 mmHg and the presenting PaCO2 was 94.5±26.2 mmHg, suggestive of absence of effective ventilation (asphyxia) at presentation. Survival with CPC 1-2 was 34.7% versus 25.9% for ETI versus SGA, respectively (p=0.12). Conclusion: Use of SGA, during prolonged CPR in refractory VT/VF OHCA, was associated with a significant increase in the proportion of patients presenting with significant hypoxemia and asphyxial physiology, thus increasing ineligibility for ECPR.

Purpose: Triple channel correction acquisition (TCCA) is a model‐based method for obtaining the characteristic curve of Gafchromic EBT2 film (EBT2). In this study the TCCA method was applied to EBT2 film dosimetry of intensity modulated radiation therapy (IMRT) and intensity modulated arc therapy (IMAT). Method and Materials:EBT2 films were calibrated by a field‐by‐field method in 13 steps. All films were scanned by using flat‐bed scanners at one day after the irradiation. Seven characteristic curves obtained by the TCCA method were compared with those of a single channel acquisition (SCA) method. For clinical applications, the planar dose distributions of IMRT and IMAT plans were compared with dose distributions measured with EBT2 films. The film analyses were performed by applying both TCCA and SCA. We chose two IMRT plans and two Varian IMAT (RapidArc) plans, which were created by the BrainLAB i‐plan and Eclipse Varian treatment planning systems for IMRT and RapidArc, respectively. Results: The constancy of the characteristic curves obtained by TCCA was better than that of SCA. The most significant difference between the characteristic curves of TCCA and SCA was observed in a low dose range between 25 cGy and 100 cGy. The results of clinical cases demonstrated that the dose difference between the measured and planned doses in high dose gradient regions was smaller with TCCA than that with SCA. Conclusions: We showed that characteristic curves obtained by the TCCA method have a good constancy compared with those of SCA. The potential advantage of TCCA was seen in high dose gradient regions in clinically relevant IMRT and IMAT cases. Hence, EBT2 film dosimetry with the TCCA method can be used for high precision patient specific QA.