Jolliet P, Tassaux D, Thouret J M, Chevrolet J C
Medical Intensive Care Division, University Hospital, Geneva, Switzerland.
Crit Care Med. 1999 Nov;27(11):2422-9. doi: 10.1097/00003246-199911000-00017.
To test the hypothesis that, in decompensated chronic obstructive pulmonary disease (COPD), noninvasive pressure support ventilation using 70:30 helium:oxygen instead of 70:30 air:oxygen could reduce dyspnea and improve ventilatory variables, gas exchange, and hemodynamic tolerance.
Prospective, randomized, crossover study.
Medical intensive care unit, university tertiary care center.
Nineteen patients with severe COPD (forced 1-sec expiratory volume of 0.83+/-0.3 l) hospitalized in the intensive care unit for noninvasive pressure support ventilation after initial stabilization with noninvasive pressure support for no more than 24 hrs after intensive care unit admission.
Noninvasive pressure support ventilation was administered in the following randomized crossover design: a) 45 min with air:oxygen or helium:oxygen; b) no ventilation for 45 min; and c) 45 min with air:oxygen or helium:oxygen.
Air:oxygen and helium:oxygen decreased respiratory rate and increased tidal volume and minute ventilation. Helium:oxygen decreased inspiratory time. Both gases increased total respiratory cycle time and decreased the inspiratory/total time ratio, the reduction in the latter being significantly greater with helium:oxygen. Peak inspiratory flow rate increased more with helium:oxygen. PaO2 increased with both gases, whereas PaCO2 decreased more with helium:oxygen (values shown are mean+/-SD) (52+/-6 torr [6.9+/-0.8 kPa] vs. 55+/-8 torr [7.3+/-1.1 kPa] and 48+/-6 torr [6.4+/-0.8 kPa] vs. 54+/-7 torr [7.2+/-0.9 kPa] for air:oxygen and helium:oxygen, respectively; p<.05). When hypercapnia was severe (PaCO2 >56 torr [7.5 kPa]), PaCO2 decreased by > or =7.5 torr (1 kPa) in six of seven patients with helium:oxygen and in four of seven patients with air:oxygen (p<.01). Dyspnea score (Borg scale) decreased more with helium:oxygen than with air:oxygen (3.7+/-1.6 vs. 4.5+/-1.4 and 2.8+/-1.6 vs. 4.6+/-1.5 for air:oxygen and helium:oxygen, respectively; p<.05). Mean arterial blood pressure decreased with air:oxygen (76+/-12 vs. 82+/-14 mm Hg; p<.05) but remained unchanged with helium:oxygen.
In decompensated COPD patients, noninvasive pressure support ventilation with helium:oxygen reduced dyspnea and PaCO2 more than air:oxygen, modified respiratory cycle times, and did not modify systemic blood pressure. These effects could prove beneficial in COPD patients with severe acute respiratory failure and might reduce the need for endotracheal intubation.
验证以下假设：在失代偿性慢性阻塞性肺疾病（COPD）患者中，使用70:30的氦氧混合气而非70:30的空气氧混合气进行无创压力支持通气，可减轻呼吸困难，并改善通气变量、气体交换及血流动力学耐受性。
前瞻性、随机、交叉研究。
大学三级护理中心的医学重症监护病房。
19例重度COPD患者（用力呼气1秒量为0.83±0.3升），入住重症监护病房后，在最初接受不超过24小时的无创压力支持稳定病情后，因无创压力支持通气而住院。
采用以下随机交叉设计进行无创压力支持通气：a）空气氧混合气或氦氧混合气通气45分钟；b）无通气45分钟；c）空气氧混合气或氦氧混合气通气45分钟。
空气氧混合气和氦氧混合气均降低了呼吸频率，增加了潮气量和分钟通气量。氦氧混合气缩短了吸气时间。两种气体均增加了总呼吸周期时间，并降低了吸气/总时间比值，氦氧混合气使后者的降低更为显著。氦氧混合气使吸气峰流速增加更多。两种气体均使PaO₂升高，而氦氧混合气使PaCO₂降低更多（所示数值为平均值±标准差）（空气氧混合气为52±6托[6.9±0.8千帕]，氦氧混合气为55±8托[7.3±1.1千帕]；空气氧混合气为48±6托[6.4±0.8千帕]，氦氧混合气为54±7托[7.2±0.9千帕]；p<0.05）。当高碳酸血症严重（PaCO₂>56托[7.5千帕]）时，7例使用氦氧混合气的患者中有6例、7例使用空气氧混合气的患者中有4例的PaCO₂下降≥7.5托（1千帕）（p<0.01）。氦氧混合气使呼吸困难评分（Borg量表）降低幅度大于空气氧混合气（空气氧混合气为4.5±1.4，氦氧混合气为3.7±1.6；空气氧混合气为4.6±1.5，氦氧混合气为2.8±1.6；p<0.05）。空气氧混合气使平均动脉血压降低（76±12对82±14毫米汞柱；p<0.05），而氦氧混合气使其保持不变。
在失代偿性COPD患者中，与空气氧混合气相比，氦氧混合气进行无创压力支持通气能更有效地减轻呼吸困难和降低PaCO₂，改变呼吸周期时间，且不影响体循环血压。这些效应可能对重度急性呼吸衰竭的COPD患者有益，并可能减少气管插管的需求。
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