Prezant D J, Aldrich T K, Karpel J P, Park S S
Department of Medicine, Montefiore Medical Center, Bronx, NY 10467.
Am Rev Respir Dis. 1990 Dec;142(6 Pt 1):1284-7. doi: 10.1164/ajrccm/142.6_Pt_1.1284.
We studied the effect of inspiratory flow rate on respiratory resistance during mechanical ventilation in 15 patients with acute respiratory failure (ARF). Resistance was measured by both constant flow inflation and occlusion methods as inspiratory flow rates were increased from 0.66 to 2.0 L/s. Endotracheal tube resistance was subtracted from total resistance to obtain respiratory resistance. In contrast to the flow-dependent increase in endotracheal tube resistance, respiratory resistance decreased continuously as flow rate and airway pressure increased, except in four of six patients with asthma in whom respiratory resistance increased as flow increased. Mechanical airway dilatation, tissue resistance, stress relaxation, and time-constant inequalities may contribute to the decrease in respiratory resistance. In status asthmaticus, however, the effects of turbulence, noncompliant airways, and/or "reflex" bronchoconstriction may be sufficient to cause a flow-dependent increase in resistance.
我们研究了15例急性呼吸衰竭（ARF）患者在机械通气期间吸气流量对呼吸阻力的影响。随着吸气流量从0.66升/秒增加到2.0升/秒，通过恒流充气和阻断法测量阻力。从总阻力中减去气管插管阻力以获得呼吸阻力。与气管插管阻力随流量增加不同，呼吸阻力随着流量和气道压力增加而持续下降，但6例哮喘患者中有4例的呼吸阻力随流量增加而增加。机械性气道扩张、组织阻力、应力松弛和时间常数不均等可能导致呼吸阻力下降。然而，在哮喘持续状态下，湍流、气道顺应性降低和/或“反射性”支气管收缩的影响可能足以导致阻力随流量增加。
