During the COVID-19 pandemic, wearing masks and maintaining social distancing have become common personal protective measures. However, there is little research on alterations in cardiopulmonary function of patients with chronic obstructive pulmonary disease (COPD) after wearing different masks.

To study the effect of wearing a surgical mask versus an N95 respirator on cardiopulmonary function in patients with COPD.

Thirty patients diagnosed with COPD in General Hospital of Xinjiang Military Region were recruited from 30th June to 10th August, 2022, and randomly assigned to either an N95 respirator group (n=15) or a surgical mask group (n=15) . Both groups underwent two bouts of walking on a treadmill at a speed of 4 km/h for 20 min with an interval of 24 h (washout period) , with the difference that N95 respirator group wore an N95 respirator in the first bout and a surgical mask in the second bout, and surgical mask group did the opposite. Arterial blood gas analysis was performed, and heart rate, blood pressure and respiratory rate were measured immediately after each bout of walking, and the overall pre- and post-experiment alterations of these indicators were calculated. The lowest percutaneous arterial oxygen saturation (SpO₂) and the maximum respiration rate during the experiment were monitored, and adverse events were recorded as well.

All the participants completed the experiment. Compared with the surgical mask group, N95 respirator group had increased difference between pre- and post-experiment arterial pH〔0.013 (0.020) vs -0.004 (0.010) , P=0.001〕, arterial partial pressure of carbon dioxide (PaCO₂) 〔1.2 (1.2) mmHg vs 0.5 (1.6) mmHg, P=0.001〕 or arterial partial pressure of oxygen (PaO₂) 〔12.5 (10.5) mmHg vs 5.0 (13.2) mmHg, P=0.002〕. In the experiment, dyspnea occurred in 25 cases (83.3%) wearing an N95 respirator, and 16 cases (53.3%) wearing a surgical mask. Compared with wearing a surgical mask, the relative risk of dyspnea in COPD patients wearing an N95 respirator during the experiment was 1.563〔95%CI (1.078, 2.264) , P=0.012〕.

COPD patients wearing an N95 respirator during walking are more likely to have alterations in arterial pH, PaCO₂ and PaO₂ levels, which affect the gas exchange and may cause dyspnea.

在新型冠状病毒感染全球流行期间，佩戴口罩和保持社交距离已成为人们常见的防护措施。但关于慢性阻塞性肺病（简称慢阻肺）患者佩戴口罩后心肺功能的变化情况尚少有研究。

探究佩戴外科口罩和N95口罩对慢阻肺患者心肺功能的影响。

招募2022-06-30—08-10于新疆军区总医院确诊的30例慢阻肺患者，使用随机数分组法将研究对象随机分配至N95口罩组（n=15）和外科口罩组（n=15）。N95口罩组和外科口罩组分前后两个阶段相互交叉进行，当首轮试验（规范佩戴口罩后患者在跑步机上以4 km/h的步行速度行走20 min）结束并经过24 h洗脱期后，将外科口罩组与N95口罩组患者对调后进行次轮试验，步骤与方法同第一阶段。试验结束时所有患者立即完成动脉血气分析并记录心率、血压、呼吸频率。计算试验后与试验前变化幅度。监测试验过程中患者的最低经皮动脉血氧饱和度（SpO₂）和最快呼吸频率，并记录不良事件发生情况。

30例患者均完成了试验。与外科口罩组相比，N95口罩组试验后与试验前酸碱度（pH）变化幅度〔0.013（0.020）与-0.004（0.010）〕、动脉血二氧化碳分压（PaCO₂）变化幅度〔1.2（1.2）mmHg与0.5（1.6）mmHg）〕和动脉血氧分压（PaO₂）变化幅度〔12.5（10.5）mmHg与5.0（13.2）mmHg〕均升高（P值分别为0.001、0.001、0.002）。试验中患者佩戴N95口罩出现呼吸困难者25例（83.3%），佩戴外科口罩出现呼吸困难者16例（53.3%）；与佩戴外科口罩相比，慢阻肺患者佩戴N95口罩出现呼吸困难的相对危险度（RR）为1.563〔95%CI（1.078，2.264），P=0.012〕。

与佩戴外科口罩相比，慢阻肺患者佩戴N95口罩更易导致pH、PaCO₂、PaO₂发生变化，影响气体交换，发生呼吸困难。