Department of Anesthesiology, University Medical Center Groningen, University of Groningen, 30001, 9700 RB Groningen, The Netherlands.
Intensive Care Med. 2013 Jun;39(6):1034-9. doi: 10.1007/s00134-013-2888-x. Epub 2013 Apr 5.
To investigate the interchangeability of mixed and central venous-arterial carbon dioxide differences and the relation between the central difference (pCO₂ gap) and cardiac index (CI). We also investigated the value of the pCO₂ gap in outcome prediction.
We performed a post hoc analysis of a well-defined population of 53 patients with severe sepsis or septic shock. Mixed and central venous pCO₂ were determined earlier at a 6 h interval (T = 0 to T = 4) during the first 24 h after intensive care unit (ICU) admittance. The population was divided into two groups based on pCO₂ gap (cut off value 0.8 kPa).
The mixed pCO₂ difference underestimated the central pCO₂ difference by a mean bias of 0.03 ± 0.32 kPa (95 % limits of agreement: -0.62-0.58 kPa). We observed a weak relation between pCO₂ gap and CI. The in hospital mortality rate was 21 % (6/29) for the low gap group and 29 % (7/24) for the high gap group; the odds ratio was 1.6 (95 % CI 0.5-5.5), p = 0.53. At T = 4 the odds ratio was 5.3 (95 % CI 0.9-30.7); p = 0.08.
From a practical perspective, the clinical utility of central venous pCO₂ values is of potential interest in determining the venous-arterial pCO₂ difference. The likelihood of a bad outcome seems to be enhanced when a high pCO₂ gap persists after 24 h of therapy.
研究混合静脉-动脉二氧化碳差值的可互换性以及中心差值（pCO₂ 间隙）与心指数（CI）之间的关系。我们还研究了 pCO₂ 间隙在预后预测中的价值。
我们对重症脓毒症或感染性休克的 53 例明确患者进行了一项事后分析。在入住重症监护病房（ICU）后的头 24 小时内，每 6 小时（T = 0 到 T = 4）测量混合静脉和中心静脉 pCO₂。根据 pCO₂ 间隙（截断值 0.8 kPa）将人群分为两组。
混合 pCO₂ 差异平均低估中心 pCO₂ 差异 0.03 ± 0.32 kPa（95 % 一致性界限：-0.62-0.58 kPa）。我们观察到 pCO₂ 间隙与 CI 之间存在弱相关关系。低间隙组的住院死亡率为 21 %（6/29），高间隙组为 29 %（7/24）；比值比为 1.6（95 % CI 0.5-5.5），p = 0.53。在 T = 4 时，比值比为 5.3（95 % CI 0.9-30.7）；p = 0.08。
从实际角度来看，确定静脉-动脉 pCO₂ 差值时，中心静脉 pCO₂ 值的临床应用具有潜在意义。当治疗 24 小时后仍存在高 pCO₂ 间隙时，不良结局的可能性似乎会增加。
