Objective: Sniff nasal inspiratory pressure (SNIP), a useful tool for the assessment of diaphragm function in patients with Amyotrophic Lateral Sclerosis (ALS), is usually performed together with lung function tests. The aim of this study was to evaluate whether SNIP results are influenced by the order of performance of the tests. Methods: 103 consecutive patients (65% males, 80% spinal onset) were recruited. The highest value of up to 10 sniffs, was recorded before (SNIPT0) and after (SNIPT1) the assessment of lung function, peak cough (PCF), and peak expiratory flow (PEF). Results: Mean and median values were respectively 31.10 and 26.00 cm H₂O for SNIPT0 and 28.93 and 25.00 cm H₂O for SNIPT1 (p < 0.001). The median value of (SNIPT1 − SNIPT0)/SNIPT0% was −7.10. Patients showing post lung function SNIP values above the median were included in Group 1 (51%), the others in group 2 (49%). Group 2 showed more severe baseline ventilatory restriction and reduction in PCF than Group 1. Positive direct relationships were found between SNIPT0 and SNIPT1 (coefficient β = 0.95, p < 0.001), and forced vital capacity and forced expiratory volume at one second. Conclusions: 50/103(49%) patients with ALS show a significant reduction in SNIP when assessed shortly after the performance of lung function tests. These patients suffer from more severe ventilatory restriction than patients not showing the reduction. Our findings suggest standardizing the order of respiratory tests during the follow up in order to avoid to misestimate the real strength of inspiratory muscles.

目的：嗅探鼻吸气压 (SNIP) 是评估肌萎缩侧索硬化症 (ALS) 患者膈肌功能的有用工具，通常与肺功能测试一起进行。本研究的目的是评估 SNIP 结果是否受测试执行顺序的影响。方法：招募了 103 名连续患者（65% 男性，80% 脊柱发病）。在评估肺功能、咳嗽峰值 (PCF) 和呼气峰值流量 (PEF) 之前 (SNIPT0) 和之后 (SNIPT1) 记录最多 10 次嗅探的最高值。结果：SNIPT0 的平均值和中值分别为 31.10 和 26.00 cm H ₂ O，SNIPT1 的平均值和中值分别为 28.93 和 25.00 cm H ₂ O（p < 0.001)。(SNIPT1 - SNIPT0)/SNIPT0% 的中值为 -7.10。显示肺功能后 SNIP 值高于中位数的患者被包括在第 1 组 (51%) 中，其他人被包括在第 2 组中 (49%)。与第 1 组相比，第 2 组表现出更严重的基线通气限制和 PCF 减少。发现 SNIPT0 和 SNIPT1（系数β  = 0.95，p  < 0.001）与一秒用力肺活量和用力呼气量之间存在正的直接关系。结论：50/103(49%) 的 ALS 患者在进行肺功能测试后不久评估时显示 SNIP 显着降低。这些患者比没有表现出减少的患者遭受更严重的通气受限。我们的研究结果建议在随访期间标准化呼吸测试的顺序，以避免错误估计吸气肌的真实力量。