Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK.
BMJ Open Respir Res. 2023 Jun;10(1). doi: 10.1136/bmjresp-2022-001537.
Accurate arterial blood gas (ABG) analysis is essential in the management of patients with hypercapnic respiratory failure, but repeated sampling requires technical expertise and is painful. Missed sampling is common and has a negative impact on patient care. A newer venous to arterial conversion method (v-TAC, Roche) uses mathematical models of acid-base chemistry, a venous blood gas sample and peripheral blood oxygen saturation to calculate arterial acid-base status. It has the potential to replace routine ABG sampling for selected patient cohorts. The aim of this study was to compare v-TAC with ABG, capillary and venous sampling in a patient cohort referred to start non-invasive ventilation (NIV).
Recruited patients underwent near simultaneous ABG, capillary blood gas (CBG) and venous blood gas (VBG) sampling at day 0, and up to two further occasions (day 1 NIV and discharge). The primary outcome was the reliability of v-TAC sampling compared with ABG, via Bland-Altman analysis, to identify respiratory failure (via PaCO) and to detect changes in PaCO in response to NIV. Secondary outcomes included agreements with pH, sampling success rates and pain.
The agreement between ABG and v-TAC/venous PaCO was assessed for 119 matched sampling episodes and 105 between ABG and CBG. Close agreement was shown for v-TAC (mean difference (SD) 0.01 (0.5) kPa), but not for CBG (-0.75 (0.69) kPa) or VBG (+1.00 (0.90) kPa). Longitudinal data for 32 patients started on NIV showed the closest agreement for ABG and v-TAC (R=0.61). v-TAC sampling had the highest first-time success rate (88%) and was less painful than arterial (p<0.0001).
Mathematical arterialisation of venous samples was easier to obtain and less painful than ABG sampling. Results showed close agreement for PaCO2 and pH and tracked well longitudinally such that the v-TAC method could replace routine ABG testing to recognise and monitor patients with hypercapnic respiratory failure.
NCT04072848; www.
gov.
准确的动脉血气（ABG）分析对于管理高碳酸血症性呼吸衰竭患者至关重要，但重复采样需要技术专业知识且具有疼痛感。漏采的情况很常见，会对患者护理产生负面影响。一种较新的静脉至动脉转换方法（v-TAC，罗氏）利用酸碱化学的数学模型、静脉血气样本和外周血氧饱和度来计算动脉酸碱状态。它有可能替代选定患者群体的常规 ABG 采样。本研究的目的是比较 v-TAC 与 ABG、毛细血管和静脉采样在被转介开始无创通气（NIV）的患者队列中的差异。
招募的患者在第 0 天同时进行 ABG、毛细血管血气（CBG）和静脉血气（VBG）采样，并在随后的两个时间点（NIV 治疗第 1 天和出院时）进行进一步采样。主要结局是通过 Bland-Altman 分析比较 v-TAC 采样与 ABG 的可靠性，以识别呼吸衰竭（通过 PaCO2）并检测对 NIV 的 PaCO2 变化。次要结局包括 pH 值、采样成功率和疼痛的一致性。
评估了 119 次 ABG 和 v-TAC/静脉 PaCO2 匹配采样和 105 次 ABG 和 CBG 采样的一致性。v-TAC 显示出接近的一致性（平均差异（SD）0.01（0.5）kPa），但 CBG （-0.75（0.69）kPa）或 VBG （+1.00（0.90）kPa）则不然。对 32 名开始接受 NIV 治疗的患者的纵向数据显示，ABG 和 v-TAC 之间的一致性最好（R=0.61）。v-TAC 采样的首次成功率最高（88%），且比动脉采样疼痛程度低（p<0.0001）。
静脉样本的数学动脉化比 ABG 采样更容易获得，且疼痛程度更低。结果显示 PaCO2 和 pH 值的一致性较好，纵向跟踪情况良好，因此 v-TAC 方法可以替代常规 ABG 测试来识别和监测高碳酸血症性呼吸衰竭患者。
NCT04072848；www.clinicaltrials.gov。
gov。
