Tong Pearl Shuang Ye, Kale Anita Sugam, Ng Kailyn, Loke Amelia Peiwen, Choolani Mahesh Arjandas, Lim Chin Leong, Chan Yiong Huak, Chong Yap Seng, Tambyah Paul Anantharajah, Yong Eu-Leong
Department of Obstetrics and Gynecology, National University Hospital, 11 Mandalay Road, Singapore, 308232 Singapore.
Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 11 Mandalay Road, Singapore, 308232 Singapore.
Antimicrob Resist Infect Control. 2015 Nov 16;4:48. doi: 10.1186/s13756-015-0086-z. eCollection 2015.
Outbreaks of emerging infectious diseases have led to guidelines recommending the routine use of N95 respirators for healthcare workers, many of whom are women of childbearing age. The respiratory effects of prolonged respirator use on pregnant women are unclear although there has been no definite evidence of harm from past use.
We conducted a two-phase controlled clinical study on healthy pregnant women between 27 to 32 weeks gestation. In phase I, energy expenditure corresponding to the workload of routine nursing tasks was determined. In phase II, pulmonary function of 20 subjects was measured whilst at rest and exercising to the predetermined workload while breathing ambient air first, then breathing through N95-mask materials.
Exercising at 3 MET while breathing through N95-mask materials reduced mean tidal volume (TV) by 23.0 % (95 % CI -33.5 % to -10.5 %, p < 0.001) and lowered minute ventilation (VE) by 25.8 % (95 % CI -34.2 % to -15.8 %, p < 0.001), with no significant change in breathing frequency compared to breathing ambient air. Volumes of oxygen consumption (VO2) and carbon dioxide expired (VCO2) were also significantly reduced; VO2 by 13.8 % (95 % CI -24.2 % to -3 %, p = 0.013) and VCO2 by 17.7 %, (95 % CI -28.1 % to -8.6 %, p = 0.001). Although no changes in the inspired oxygen and carbon dioxide concentrations were demonstrated, breathing through N95-mask materials during low intensity work (3 MET) reduced expired oxygen concentration by 3.2 % (95 % CI: -4.1 % to -2.2 %, p < 0.001), and increased expired carbon dioxide by 8.9 % (95 % CI: 6.9 % to 13.1 %; p <0.001) suggesting an increase in metabolism. There were however no changes in the maternal and fetal heart rates, finger-tip capillary lactate levels and oxygen saturation and rating of perceived exertion at the work intensity investigated.
Breathing through N95 mask materials have been shown to impede gaseous exchange and impose an additional workload on the metabolic system of pregnant healthcare workers, and this needs to be taken into consideration in guidelines for respirator use. The benefits of using N95 mask to prevent serious emerging infectious diseases should be weighed against potential respiratory consequences associated with extended N95 respirator usage.
The study was registered at clinicaltrials.gov, identifier NCT00265926.
新发传染病的爆发促使指南建议医护人员常规使用N95口罩，其中许多是育龄妇女。尽管过去没有明确的有害证据，但长期使用口罩对孕妇呼吸的影响尚不清楚。
我们对妊娠27至32周的健康孕妇进行了一项两阶段对照临床研究。在第一阶段，确定了与常规护理任务工作量相对应的能量消耗。在第二阶段，测量了20名受试者在休息时以及按照预定工作量进行运动时的肺功能，先是呼吸环境空气，然后通过N95口罩材料呼吸。
在通过N95口罩材料呼吸的同时以3代谢当量进行运动，平均潮气量（TV）降低了23.0%（95%置信区间-33.5%至-10.5%，p＜0.001），分钟通气量（VE）降低了25.8%（95%置信区间-34.2%至-15.8%，p＜0.001），与呼吸环境空气相比呼吸频率无显著变化。耗氧量（VO2）和呼出二氧化碳量（VCO2）也显著降低；VO2降低了13.8%（95%置信区间-24.2%至-3%，p = 0.013），VCO2降低了17.7%（95%置信区间-28.1%至-8.6%，p = 0.001）。尽管吸入氧气和二氧化碳浓度没有变化，但在低强度工作（3代谢当量）期间通过N95口罩材料呼吸使呼出氧气浓度降低了3.2%（95%置信区间：-4.1%至-2.2%，p＜0.001），呼出二氧化碳增加了8.9%（95%置信区间：6.9%至13.1%；p＜0.001），表明新陈代谢增加。然而，在所研究的工作强度下，母婴心率、指尖毛细血管乳酸水平、血氧饱和度和主观用力程度评分均无变化。
已表明通过N95口罩材料呼吸会阻碍气体交换，并给怀孕医护人员的代谢系统带来额外负担，这在口罩使用指南中需要加以考虑。使用N95口罩预防严重新发传染病的益处应与长时间使用N95口罩相关的潜在呼吸后果相权衡。
该研究已在clinicaltrials.gov注册，标识符为NCT00265926。
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