• Yuankai Zhou, Huaiwu He, Na Cui, Hao Wang, Xiang Zhou, and Yun Long.
• Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
• J Crit Care. 2021 Dec 1; 66: 148-153.

PurposeThis study aimed to evaluate the effects of acute hyperventilation on central venous-to-arterial carbon dioxide tension difference (Pv-aCO2), central venous oxygen saturation (ScvO2), central venous-to-arterial CO2 difference/arterial-central venous O2 difference ratio (CO2GAP-Ratio), and peripheral perfusion index (PI) in hemodynamically stable critically ill patients.MethodsFifty-four mechanically ventilated patients were evaluated. The cardiac index, Pv-aCO2, ScvO2, CO2GAP-Ratio, PI, and arterial and venous blood gas parameters were measured in the first set of measurements. Then, alveolar ventilation was increased by raising the respiratory rate (10 breaths/min). After a 30 min hyperventilation period, the second set of measurements was recorded.ResultsAcute hyperventilation induces an increase in Pv-aCO2 (from 3.87 ± 1.31 to 8.44 ± 1.81 mmHg, P < 0.001) and a decrease in ScvO2(from 71.78 ± 4.82 to 66.47 ± 5.74%, P < 0.001). The CO2GAP-Ratio was significantly increased(from 0.97 ± 0.40 to 1.74 ± 0.46, P < 0.001), and the PI showed a remarkable decrease caused by acute hyperventilation(from 1.82 ± 1.14 to 1.40 ± 0.99，P = 0.04). Hyperventilation-induced ∆_Pv-aCO2 was negatively correlated with ∆PaCO2(r = -0.572, P<0.001). The change in ∆_PaCO2 was correlated with ∆_ScvO2(r = 0.450, P<0.001). However, the left ventricular outflow tract velocity time integral (LVOT-VTI) remained unchanged during hyperventilation.ConclusionsAcute hyperventilation induced an increase in oxygen consumption and decreased peripheral tissue perfusion in patients. For critical care patients, it is necessary to pay attention to the influence of hyperventilation on peripheral tissue perfusion indices and oxygen consumption indices.Copyright © 2021 Elsevier Inc. All rights reserved.

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