Lin Fang-Chi, Chen Yi-Chu, Chang Huei-Ing, Chang Shi-Chuan
Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Chest. 2005 Mar;127(3):1058-64. doi: 10.1378/chest.127.3.1058.
Prone positioning may improve oxygenation in patients with acute lung injury/ARDS. However, the beneficial effect of prone positioning on gas exchange has never been investigated in patients with diffuse pulmonary infiltrates who breathe spontaneously.
To evaluate the effect of body position on gas exchange in patients with idiopathic pulmonary alveolar proteinosis (PAP) with special reference to the benefit of prone positioning.
A prospective study.
Tertiary medical center.
Eight patients with PAP were studied on 25 occasions using spirometry, body plethysmography, and single-breath diffusing capacity of the lung for carbon monoxide (Dlco). Arterial blood gas levels were measured in the sitting position and in four lying positions randomly while patients breathed room air. To serve as control subjects, 16 age-matched healthy hospital personnel were studied. To evaluate the impact of oxygen therapy on positional effect in gas exchange, arterial blood gas levels were measured in the supine and prone positions in some PAP patients while breathing 40% oxygen.
Normal to varying degrees of restrictive ventilatory defect and gas exchange impairment, as evidenced by Dlco, Pao(2), and alveolar-arterial oxygen pressure difference (P[A-a]O(2)), were found in PAP patients. The ventilatory function parameters correlated positively with Pao(2) and negatively with P(A-a)O(2). The values of Pao(2) and P(A-a)O(2) measured in four lying positions showed no significant difference in both PAP patients and healthy control subjects. Furthermore, the differences in Pao(2) and P(A-a)O(2) between measurements made in the supine and prone positions and the ratio of Pao(2) measured in the prone position/Pao(2) measured in the supine position were comparable between PAP patients and healthy control subjects. Arterial blood gas levels showed no significant difference between measurements made in PAP patients in the supine and prone positions while breathing 40% oxygen.
Positional change did not significantly affect gas exchange, and no benefit of prone positioning was found in both PAP patients and healthy control subjects. Further studies are needed to verify the benefit of prone ventilation in patients with diffuse pulmonary disorders who breathe spontaneously.
俯卧位可能改善急性肺损伤/急性呼吸窘迫综合征患者的氧合。然而，对于自主呼吸的弥漫性肺浸润患者，俯卧位对气体交换的有益作用从未被研究过。
评估体位对特发性肺泡蛋白沉积症（PAP）患者气体交换的影响，并特别关注俯卧位的益处。
一项前瞻性研究。
三级医疗中心。
对8例PAP患者进行了25次研究，采用肺活量测定法、体容积描记法和单次呼吸一氧化碳肺弥散量（Dlco）。在患者呼吸室内空气时，随机测量其坐位及四个卧位的动脉血气水平。为作为对照，研究了16名年龄匹配的健康医院工作人员。为评估氧疗对气体交换中体位效应的影响，在部分PAP患者呼吸40%氧气时，测量其仰卧位和俯卧位的动脉血气水平。
PAP患者存在正常至不同程度的限制性通气功能障碍和气体交换受损，这由Dlco、动脉血氧分压（Pao₂）和肺泡-动脉氧分压差（P[A-a]O₂）证实。通气功能参数与Pao₂呈正相关，与P(A-a)O₂呈负相关。在四个卧位测量的Pao₂和P(A-a)O₂值在PAP患者和健康对照者中均无显著差异。此外，PAP患者和健康对照者在仰卧位和俯卧位测量的Pao₂和P(A-a)O₂差异以及俯卧位测量的Pao₂/仰卧位测量的Pao₂比值相当。在呼吸40%氧气时，PAP患者仰卧位和俯卧位测量的动脉血气水平无显著差异。
体位改变对气体交换无显著影响，在PAP患者和健康对照者中均未发现俯卧位的益处。需要进一步研究以证实俯卧位通气对自主呼吸的弥漫性肺部疾病患者的益处。
