Settergren G, Angdin M, Astudillo R, Gelinder S, Liska J, Lundberg J O, Weitzberg E
Department of Surgical Sciences, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
Acta Physiol Scand. 1998 Jul;163(3):235-9. doi: 10.1046/j.1365-201x.1998.00352.x.
Nitric oxide is present in high concentration in the human nasal airways. During inspiration through the nose a bolus is transported to the lungs. In a randomized cross-over study the effect of two different patterns of breathing, nasal breathing and mouth breathing, was evaluated in 10 patients (mean age 65 years), breathing room air the morning of the first post-operative day after open heart surgery. Nasal breathing is defined as inspiration through the nose and expiration through the mouth, whilst mouth breathing is the converse of this: inspiration through the mouth and expiration through the nose. Pressure in the pulmonary artery and left atrium or pulmonary artery wedge was measured together with thermodilution cardiac output and arterial and mixed venous oxygenation and acid-base parameters. Pulmonary vascular resistance index (PVRI), venous admixture and alveolar-arterial gradient were calculated. Nasal breathing resulted in a lower PVRI, 256 dyn s cm-5 cm-2 vs. 287 (P < 0.01). The oxygen and carbon dioxide tension and pH of arterial and mixed venous blood, venous admixture and the alveolar-arterial gradient remained unchanged. The decreased level of PVRI during nasal breathing compared to that during mouth breathing supports the notion, that endogenous nitric oxide acts as an airborne messenger to modulate the pulmonary vascular tone during normal breathing.
一氧化氮在人类鼻气道中浓度很高。在经鼻吸气时，一团气体被输送到肺部。在一项随机交叉研究中，对10名患者（平均年龄65岁）进行了评估，观察两种不同呼吸模式（鼻呼吸和口呼吸）的效果，这些患者在心脏直视手术后第一天早晨呼吸室内空气。鼻呼吸定义为经鼻吸气、经口呼气，而口呼吸则相反：经口吸气、经鼻呼气。测量肺动脉和左心房或肺动脉楔压，同时测量热稀释心输出量以及动脉和混合静脉血氧合及酸碱参数。计算肺血管阻力指数（PVRI）、静脉血掺杂和肺泡-动脉血氧分压差。鼻呼吸导致较低的PVRI，分别为256 dyn s cm-5 cm-2和287（P < 0.01）。动脉血和混合静脉血的氧分压、二氧化碳分压及pH值、静脉血掺杂和肺泡-动脉血氧分压差均保持不变。与口呼吸相比，鼻呼吸时PVRI水平降低，这支持了内源性一氧化氮作为一种空气传播信使在正常呼吸过程中调节肺血管张力的观点。
