Jaeschke R, Guyatt G H, Cook D, Morris J, Willan A, McIlroy W, Harper S, Ramsdale H, Haddon R, Fitzgerald M J
Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Respir Med. 1993 Aug;87(6):433-8. doi: 10.1016/0954-6111(93)90069-c.
To determine the increase in FEV1 associated with increasing doses of inhaled terbutaline and salbutamol, the reproducibility of the increase in FEV1, and the reproducibility of the associated optimal bronchodilator dose, in patients with chronic airflow limitation (CAL).
Double-blind, randomized, controlled trial examining spirometric response to cumulative doses of bronchodilators.
Patients with clinical diagnosis of CAL, FEV1 below 70% predicted, and FEV1 to FVC ratio less than 0.7 after administration of bronchodilator recruited from secondary care respirology practices.
The estimates of maximum and optimal bronchodilation, as well as the associated drug dosages, were established in each patient on three occasions (twice on terbutaline and once on salbutamol). The 'optimal' drug dose was defined as the lowest dose associated with an FEV1 not exceeded by 50 ml on any other dose.
Thirty-five patients completed the trial. FEV1 improved from 0.93 to a maximum of 1.191 with terbutaline (average of the two administrations) and from 0.951 to 1.141 with inhaled salbutamol (difference in increase in FEV1 between terbutaline and salbutamol P = 0.006). In less than 50% of cases administration of more than four puffs of bronchodilator resulted in FEV1 increase by more than 50 ml. The average dose of salbutamol and terbutaline associated with optimal bronchodilation were 430 micrograms and 1160 micrograms respectively. Patients varied widely in the optimal dose. Estimates of optimal dose were not reproducible (intraclass correlation coefficient < 0.5).
Substantial incremental increase in FEV1 in response to increasing doses of beta-agonists beyond those commonly used in clinical practice is restricted to a minority of patients. Lack of reproducibility limits the clinical usefulness of establishing the optimal dose of beta-agonist for a given patient.
确定慢性气流受限（CAL）患者吸入不同剂量特布他林和沙丁胺醇后第一秒用力呼气容积（FEV1）的增加情况、FEV1增加的可重复性以及相关最佳支气管扩张剂剂量的可重复性。
双盲、随机、对照试验，检测对支气管扩张剂累积剂量的肺量计反应。
从二级护理呼吸科诊所招募的临床诊断为CAL、FEV1低于预测值的70%且使用支气管扩张剂后FEV1与用力肺活量（FVC）比值小于0.7的患者。
在每位患者身上三次测定最大和最佳支气管扩张情况以及相关药物剂量（两次使用特布他林，一次使用沙丁胺醇）。“最佳”药物剂量定义为在任何其他剂量下FEV1不超过50 ml的最低剂量。
35名患者完成试验。使用特布他林（两次给药的平均值）时FEV1从0.93升至最高1.191，使用吸入沙丁胺醇时从0.951升至1.141（特布他林和沙丁胺醇之间FEV1增加量的差异P = 0.006）。在不到50%的病例中，使用超过四喷支气管扩张剂导致FEV1增加超过50 ml。与最佳支气管扩张相关的沙丁胺醇和特布他林的平均剂量分别为430微克和1160微克。患者的最佳剂量差异很大。最佳剂量的估计值不可重复（组内相关系数<0.5）。
超出临床常用剂量的β受体激动剂剂量增加所导致的FEV1显著增加仅限于少数患者。缺乏可重复性限制了为特定患者确定最佳β受体激动剂剂量的临床实用性。
