Intensive Care Unit, Hospital Universitari Son Dureta, Andrea Doria 55, 07014, Palma de Mallorca, Illes Balears, Spain.
Respir Care. 2010 Nov;55(11):1442-8.
In obesity-hypoventilation-syndrome patients mechanically ventilated for hypercapnic respiratory failure we investigated the relationship between CO₂ response, body mass index, and plasma bicarbonate concentration, and the effect of acetazolamide on bicarbonate concentration and CO₂ response.
CO₂ response tests and arterial blood gas analysis were performed in 25 patients ready for a spontaneous breathing test, and repeated in a subgroup of 8 patients after acetazolamide treatment. CO₂ response test was measured as (1) hypercapnic drive response (the ratio of the change in airway occlusion pressure 0.1 s after the start of inspiratory flow to the change in P(aCO₂)), and (2) hypercapnic ventilatory response (the ratio of the change in minute volume to the change in P(aCO₂)).
We did not find a significant relationship between CO₂ response and body mass index. Patients with higher bicarbonate concentration had a more blunted CO₂ response. Grouping the patients according to the first, second, and third tertiles of the bicarbonate concentration, the hypercapnic drive response was 0.32 ± 0.17 cm H₂O/mm Hg, 0.22 ± 0.15 cm H₂O/mm Hg, and 0.10 ± 0.06 cm H₂O/mm Hg, respectively (P = .01), and hypercapnic ventilatory response was 0.46 ± 0.23 L/min/mm Hg, 0.48 ± 0.36 L/min/mm Hg, and 0.22 ± 0.16 L/min/mm Hg, respectively (P = .04). After acetazolamide treatment, bicarbonate concentration was reduced by 8.4 ± 3.0 mmol/L (P = .01), and CO₂ response was shifted to the left, with an increase in hypercapnic drive response, by 0.14 ± 0.16 cm H₂O/mm Hg (P = .02), and hypercapnic ventilatory response, by 0.11 ± 0.22 L/min/mm Hg (P = .33).
Patients with obesity-hypoventilation syndrome and higher bicarbonate concentrations had a more blunted CO₂ response. Body mass index was not related to CO₂ response. Acetazolamide decreased bicarbonate concentration and increased CO₂ response.
在肥胖低通气综合征患者因高碳酸血症呼吸衰竭行机械通气时，我们研究了二氧化碳反应、体重指数和血浆碳酸氢盐浓度之间的关系，以及乙酰唑胺对碳酸氢盐浓度和二氧化碳反应的影响。
25 例准备行自主呼吸试验的患者进行了二氧化碳反应试验和动脉血气分析，并在 8 例患者中重复了乙酰唑胺治疗后的试验。二氧化碳反应试验测量如下：（1）高碳酸血症驱动反应（吸气开始后 0.1 秒气道闭塞压的变化与 P(aCO₂)变化的比值）；（2）高碳酸血症通气反应（分钟通气量变化与 P(aCO₂)变化的比值）。
我们没有发现二氧化碳反应与体重指数之间存在显著关系。碳酸氢盐浓度较高的患者二氧化碳反应更迟钝。根据碳酸氢盐浓度的第一、第二和第三三分位数对患者进行分组，高碳酸血症驱动反应分别为 0.32±0.17 cm H₂O/mm Hg、0.22±0.15 cm H₂O/mm Hg 和 0.10±0.06 cm H₂O/mm Hg（P=0.01），高碳酸血症通气反应分别为 0.46±0.23 L/min/mm Hg、0.48±0.36 L/min/mm Hg 和 0.22±0.16 L/min/mm Hg（P=0.04）。乙酰唑胺治疗后，碳酸氢盐浓度降低 8.4±3.0 mmol/L（P=0.01），二氧化碳反应向左移位，高碳酸血症驱动反应增加 0.14±0.16 cm H₂O/mm Hg（P=0.02），高碳酸血症通气反应增加 0.11±0.22 L/min/mm Hg（P=0.33）。
肥胖低通气综合征患者碳酸氢盐浓度较高时，二氧化碳反应更迟钝。体重指数与二氧化碳反应无关。乙酰唑胺降低碳酸氢盐浓度并增加二氧化碳反应。
