Name: effects of surgical masks on cardiopulmonary function in healthy subjects
Uploaded: 2021-02-12T14:30:00.000+00:00
Duration: 6 min 57 s
Description: Watch this Scientific Journal Video about Effects of Surgical Masks on Cardiopulmonary Function in Healthy Subjects at JoVE.com

This study was supported by National Natural Science Foundation for Young Scientists of China (No.81902281); General Guidance Project of Guangzhou Health and Family Planning Commission (No.20191A0011091 and 20201A011108), Guangdong Provincial Department of Education (No. 2019KQNCX119) and Guangzhou Key Laboratory Fund (No.201905010004). This study also thanks Lixin Zhang, Peilin Ruan, Kaihang Ji, and Gulifeiya Tuerxun from Guangzhou Medical University for data collection.

The clinical project was approved by the Medical Ethics Association of the Fifth Affiliated Hospital of Guangzhou Medical University (No. KY01-2020-06-06) and has been registered at the China Clinical Trial Registration Center (No. ChiCTR2000033449) and entitled &#34;The effects of masks on cardiopulmonary and lower limb function&#34;.
1. Participant recruitment
<ol>
	<li>Include subjects between 18 and 26 years old: who can pass the PAR-Q test6; are physically healthy; without professional sports training experience; and able to understand the experiment and voluntarily cooperate with the whole test process.</li>
	<li>Exclude subjects: with cardiovascular diseases and respiratory diseases; with lower limb motor dysfunction caused by other diseases; who cannot cooperate with the experiment; and smokers7.</li>
	<li>Obtain written informed consent from each subject before their participation.</li>
	<li>Inform the subject that strenuous activities are prohibited 48 h before the test and during the test, and that food and beverages (except water) are not allowed 2 h before the test.</li>
	<li>Collect the subjects&#39; basic information (name, gender, date of birth, height, weight).</li>
	<li>Randomly allocate the subjects into two groups by SPSS generated digit table. Group 1 first received CPET in the mask-on condition followed by 48 h of washout, and then received CPET in the mask-off condition. Group 2 first received CPET in the mask-off condition followed by 48 h of washout, then received CPET in the mask-on condition.</li>
</ol>
2. Laboratory settings and equipment preparation
<ol>
	<li>Set the laboratory temperature to 25 &#176;C and equip with first aid equipment.</li>
	<li>Calibrate the cardiopulmonary function analyzer to ensure the accuracy of the CPET test, including flow sensor calibration, indoor air calibration, gas analysis calibration, and respiratory rate calibration. 
	&#8203;NOTE: For gas analysis calibration, use 5% CO2 and 16% O2 concentrations and N2 for balance.</li>
</ol>
3. Spirometry
<ol>
	<li>Ask the subject to sit upright without leaning on the back of the chair, with their feet on the ground, but without tilting their feet. Ask them to keep their head at a natural level or slightly tilted upwards, but not to bend their head down or bend over.</li>
	<li>Forced Vital Capacity (FVC) test: Ask the subject to breathe calmly for 5 s, inhale strongly, and then exhale strongly for 6 s. Finally, inhale back and keep breathing calmly. Perform the whole procedure under the guidance of a doctor or a formally trained exercise physiologist.</li>
	<li>Maximum Voluntary Ventilation (MVV) test: Ask the subject to breathe calmly four or five times. Then repeat the breath continuously for 12 s or 15 s at the maximum breathing amplitude and the fastest breathing speed after the baseline with expiratory volume is stable (Figure 1). 
	&#8203;NOTE: If the subject does not perform well during static lung function test, the subject will be asked to perform the tests one more time after a 3-min rest. If the subject fails the test twice, exclude the subject.</li>
</ol>
4. Cardiopulmonary exercise test (CPET)
<ol>
	<li>Subject preparation for CPET
	<ol>
		<li>Briefly introduce the process to the subject.</li>
		<li>Scrape the body hair at the position of the electrocardiograph (ECG) electrodes (V1 to V6), and then use 75% alcohol to remove extra dander and grease. 
		&#8203;NOTE: V1 is the 4th intercostal space to the right of the sternum. V2 is the 4th intercostal space, to the left of the sternum, V3 is between V2 and V4 electrodes, V4 is the 5th intercostal space on the midclavicular line, V5 is the 5th intercostal space, on the anterior axillary line, and V6 is the 5th intercostal space on the left midaxillary line. Place limb electrodes for the arms in the sub-clavicular areas, and place limb electrodes for the legs placed on the trunk at the level of the bottom rib. The electrode placement should be lateral to avoid excessive movement artifact during cycling.</li>
		<li>Place the ECG electrodes and attach them to the 12-lead ECG wires.</li>
		<li>Fix the ECG machine to the chest using a strap (Figure 2).</li>
		<li>Choose a mask that fits the size of the subject&#39;s face and attach it firmly to the face to ensure that there is no gap between the mask and the face (Figure 3). 
		NOTE: The tester could use their hand to press gently on the vest and lightly exhale to ensure that there is no gap.</li>
		<li>Fix the flow meter on the vent and then fix the K4 device onto the vest (Figure 4).</li>
		<li>Sit on the seat and adjust the height of the handlebars to a comfortable position for the subject.</li>
		<li>Grab the handlebar with both hands and step on the pedals with bilateral feet to ensure that the right knee joint bends with flexion at 30&#176;.</li>
		<li>Place a blood pressure cuff on the upper-right arm for dynamic blood pressure recording. Place a finger pulse oxygen on the left index finger for dynamic recording of blood oxygen.</li>
		<li>Calculate the subject&#39;s exercise resistance/increased incremental per min (W) parameters and set the progressive resistance plan for the exercise phase8. 
		NOTE: Exercise resistance (male) = [(height - age) * 20 - (150 + 6 * weight)] / 100 
		Exercise resistance (female) = [(height - age) * 14 - (150 + 6 * weight)] / 100</li>
	</ol>
	</li>
	<li>CPET executing phase 
	&#8203;NOTE: Ask the subject not to speak during the whole procedure to prevent extra exhalation and inhalation during speaking, which might affect the accuracy of the cardiopulmonary data. Ask the subject to please raise their hand to indicate if there is any questions or discomfort that results in the test interruption.
	<ol>
		<li>Click on the Start button to activate cycle ergometer by tester.</li>
		<li>Keep a static sitting posture for 2 min (Rest stage).</li>
		<li>Start cycling for 2 min (Warm-up stage: resistance to 0 W, speed to 60 rpm).</li>
		<li>Continue cycling until the time point when the subject could not maintain or show the ending signs (Ramp exercise stage: Incremental resistance, X watt resistance per min, 60 rpm). 
		&#8203;NOTE: X watt resistance per min is based on the formulas in step 4.1.10.</li>
		<li>Ask the subject to cycle for 3 min (cool-down stage: resistance to 0 W, speed to 40 rpm).</li>
		<li>Keep the static sitting posture for 3 min for observation of vital signs (observation stage). 
		&#8203;NOTE: Criteria for discontinuing are as follows: Subjects are encouraged to exercise to their maximum endurance or until the practitioners end the exercise due to symptoms such as ischemic ECG changes, complex ectopy, second or third degree heart block, fall in systolic pressure &#62;20 mm Hg from the highest value during the test, hypertension (&#62;250 mm Hg systolic; &#62;120 mm Hg diastolic), severe desaturation (oxyhemoglobin saturation (SpO2) &#8804; 80%), symptoms and signs of severe hypoxemia (sudden pallor, loss of coordination, mental confusion, dizziness, faintness), signs of respiratory failure, or exhaustion (Borg &#8805; 17-18 points) failed maintaining the cycling speed (lower than 40 rpm). The test will be terminated immediately if the subjects show extreme verbal or physical fatigue7, which is lower than 40 rpm.</li>
		<li>Remove data acquisition equipment, face mask, vest, and ECG electrodes.</li>
	</ol>
	</li>
</ol>
5. CPET post testing
<ol>
	<li>Use the Rating of Perceived Exertion (RPE) scale to measure physical activity intensity levels that are apparently related to the heart rate (HR) during exercise9,10.</li>
	<li>Use the Borg&#39;s scale (6-20 scale) to evaluate exertion of resistance training 11. A score of 6 represents resting activity with no effort and a score of 20 represents exhaustive exercise.</li>
</ol>
6. Statistical analysis
<ol>
	<li>Analyze the data using SPSS software (version 25) and the methodology referenced in the previous study12.</li>
	<li>Present the parametric data as mean and standard deviation (SD) if normally distributed or median if not.</li>
	<li>Allocate the subjects into male or female groups for statistical analysis, respectively.</li>
	<li>Use the paired t-test to compare the differences of CPET parameters between subjects in the mask-on condition and mask-off condition. Statistical significance is P &#60; 0.05.</li>
</ol>

<ol>
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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perceived+exertion+:+influence+of+age+and+cognitive+development.">Perceived exertion : influence of age and cognitive development.</a> Sports Medicine. 36 (11), 911-928 (2006).</li><li>Al-Shair, K., Kolsum, U., Singh, D., Vestbo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Effect+of+Fatigue+and+Fatigue+Intensity+on+Exercise+Tolerance+in+Moderate+COPD.">The Effect of Fatigue and Fatigue Intensity on Exercise Tolerance in Moderate COPD.</a> Lung. 194 (6), 889-895 (2016).</li><li>Zhang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Effects+of+Transcranial+Direct+Current+Stimulation+Versus+Electroacupuncture+on+Working+Memory+in+Healthy+Subjects.">The Effects of Transcranial Direct Current Stimulation Versus Electroacupuncture on Working Memory in Healthy Subjects.</a> Journal of Alternative and Complementary Medicine. 25 (6), 637-642 (2019).</li><li>Suzuki, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relations+between+strength+and+endurance+of+leg+skeletal+muscle+and+cardiopulmonary+exercise+testing+parameters+in+patients+with+chronic+heart+failure.">Relations between strength and endurance of leg skeletal muscle and cardiopulmonary exercise testing parameters in patients with chronic heart failure.</a> Journal of Cardiology. 43 (2), 59-68 (2004).</li><li>Bouwsema, M. 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The authors have nothing to disclose.

CPET provides valuable insights into the comprehensive functions of cardiovascular, ventilation, and skeletal muscle systems13. We proposed a CPET protocol on mask-on and mask-off conditions to explore the effect of the surgical mask on the cardiopulmonary function in healthy young subjects.
The design of this protocol was based on three main points. First, we recruited young healthy college students as the subjects for the study due to relatively high intensityof CPET in mask-on condition and similar physical fitness. Second, the subjects should be allocated into a male group and a female group considering the gender as the major factor in pulmonary function based on the spirometry results and previous research14. Third, we randomized the order of conditions (mask-on and mask-off) during CPET to eliminate the potential bias brought by sequencing.
Although the recruited subjects showed no significant difference on subjective sensation between two condition CPETs (mask- on and mask-off condition) based on the RPE scale and Borg's scale, there were some objective cardiopulmonary parameters that were significantly decreased by wearing a mask, such as in VO2/kg (LT), O2/HR (peak), VT (peak), and VE (peak). Thedecrease in VO2/kg (LT) suggests that wearing a mask might reduce the ability of muscle mitochondria to use oxygen, thereby affecting exercise capacity. The decrease in O2/HR (peak) indicated decreased cardiac output. The increased VE (peak) suggested wearing a mask might affect carbon dioxide emissions. All these affected parameters indicate that the subjects with cardiopulmonary diseases might have a higher risk when they do the aerobic exercise wearing a surgical mask. Moreover, gender differences might also be a factor in the effects of masks on cardiopulmonary function. For example, just the female group showed a significant decrease in VO2/kg (peak) after wearing a mask. Due to VO2/kg (peak) as the major parameter of aerobic exercise capacity evaluation, the result indicated that the influence of wearing a mask might be more obvious for females, especially during vigorous exercise.
This study has two main limitations. First, the sample size was small, although we recruited subjects with similar physical baseline characteristics and the representative results already showed some significant differences. Second, this study only recruited healthy young subjects, although we ensured maximum consistency in this pilot study. In future research, we could recruit more subjects in different age stratification and combined with cardiopulmonary diseases to extend our protocol to the wide population. Such work would help guide mask-wearing during daily life, especially during the epidemic stage of respiratory infectious diseases.

Wearing a face mask in public areas might impede the spread of an infectious disease by preventing both the inhalation of infectious droplets and their subsequent exhalation and dissemination1. Although the effect of reducing the risk of transmission of respiratory viruses remains controversial, wearing masks remains one of the major ways people in the community have chosen to prevent the spread of droplets among individuals in daily life2,3,4.
Different types of masks have different effects on increasing expiratory resistance and inspiratory resistance5. Meanwhile, during a respiratory disease pandemic, people (including healthy people and patients with cardiopulmonary diseases) might need to wear masks for a long time to perform daily activities. However, there are few studies on the effect of wearing a mask on cardiopulmonary function.
Cardiopulmonary exercise testing (CPET) is an important means of cardiovascular rehabilitation risk assessment by reflecting various parameters of the body&#39;s cardiopulmonary function during exercise with increasing load and is considered to be the gold standard for cardiopulmonary reserve testing2. We use CPET under different conditions (mask-on and mask-off) to study the changes in cardiopulmonary function parameters of healthy young subjects, to evaluate the interference of masks objectively and quantitatively on cardiorespiratory reserve and exercise endurance from a novel methodological perspective to guide the application of masks in particular respiratory infectious disease pandemic. Although FFP2/N95 has been suggested to be more efficacious than surgical masks at reducing exposure to viral infections, medical-surgical masks are more convenient and common to obtain and use than FFP2/N95 face masks. Thus, this study focuses only on the effects of medical surgical masks on cardiopulmonary function.

<table><tbody><tr><td>Cardiopulmonary test system</td><td>COSMED Srl - Italy</td><td>K4b2</td><td>Pulmonary Function Equipment</td></tr><tr><td>Cycle for CPET</td><td>COSMED Srl - Italy</td><td>ergoline 100P</td><td>cycle ergometer 100 P w/BP</td></tr><tr><td>Eectrocardiograph&amp;nbsp;</td><td>COSMED Srl - Italy</td><td>Quark T12x</td><td>12-Channel ECG Street Test Unit</td></tr><tr><td>Mask</td><td>COSMED Srl - Italy</td><td>Small,Medium,Large</td><td>V2 Mask</td></tr><tr><td>Software</td><td>COSMED Srl - Italy</td><td>PFT SUITE</td><td>PC Software</td></tr><tr><td>Surgical masks</td><td></td><td></td><td></td></tr></tbody></table>

effects of surgical masks on cardiopulmonary function in healthy subjects

We study the effect of surgical masks on cardiopulmonary function based on a cardiopulmonary exercise test (CPET). This study shows that surgical masks reduce cardiopulmonary exercise capacity and ventilation in healthy young subjects and wearing masks might affect aerobic exercise capacity more in female subjects than in male subjects.

Ten subjects (five males and five females) from the Department of Rehabilitation Medicine at Guangzhou Medical University were recruited in this pilot study. The participants had similar baseline characteristics, such as age (mean age: male 21.00 &#177; 1.58 years; female 21.20 &#177; 0.45 years) and physical fitness [sports activity and body mass index (BMI)]. There were no significant differences in age, height, or BMI between the male and female groups. Moreover, for the spirometry, the female group showed lower FVC, lowered forced expiratory volume in 1 s (FEV1), lower MVV, and lowered peak expiratory flow (PEF) compared with the male group (Table 1).
The results of CPET under different conditions (mask-on and mask-off) are depicted in Table 2. For exercise tolerance and cardiac function, compared to the mask-off condition, both male and female groups during the mask-on condition showed a significant decrease in anaerobic threshold per kilogram, i.e., VO2/kg (LT), and oxygen pulse, i.e., O2/HR (peak), whereas no significant differences in oxygen uptake related to work rate, i.e., &#916;VO2/&#916;WR and HR (rest). Moreover, the male group also showed a significant decrease in HR (rest), and the female group showed a significant decrease in peak oxygen uptake per kilogram, i.e., VO2/kg (peak) during the mask-on condition. For ventilatory function, compared to mask-off condition, both male and female groups during mask-on condition showed a significant decrease in tidal volume, i.e., VT (peak), but no differences were found in the breathing reserve in percentage, i.e., BR%. For gas exchange, compared with the mask-off condition, both male and female groups during the mask-on condition showed a significant decrease in the ventilation, i.e., VE (peak), but no differences were found in VE/VCO2. For the total CPET performance, both male and female groups showed no difference in Loadmax, RPE scale, and Borg&#39;s scale.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62121/62121fig01.jpg" /> 
Figure 1: Diagram for spirometry. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62121/62121fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/62121/62121fig02.jpg" /> 
Figure 2: The ECG electrode settings. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62121/62121fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/62121/62121fig03.jpg" /> 
Figure 3: Fitting of mask. (A) shows the mask-off condition. (B) shows the mask-on condition. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62121/62121fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/62121/62121fig04.jpg" /> 
Figure 4: Diagram for CPET settings. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62121/62121fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td rowspan="2">Parameters</td>
			<td rowspan="2">Unit</td>
			<td colspan="2">Male group</td>
			<td colspan="2">Female group</td>
			<td rowspan="2">P value</td>
		</tr>
		<tr>
			<td colspan="2">(n=5)</td>
			<td colspan="2">(n=5)</td>
		</tr>
		<tr>
			<td>Age</td>
			<td>years</td>
			<td colspan="2">21.00&#177;1.58</td>
			<td colspan="2">21.20&#177;0.45</td>
			<td>0.792</td>
		</tr>
		<tr>
			<td>Height</td>
			<td>cm</td>
			<td colspan="2">172.60&#177;4.45</td>
			<td colspan="2">157.00&#177;3.80</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td>Weight</td>
			<td>kg</td>
			<td colspan="2">59.40&#177;3.50</td>
			<td colspan="2">49.10&#177;2.49</td>
			<td>0.001</td>
		</tr>
		<tr>
			<td>BMI</td>
			<td>kg/m2</td>
			<td colspan="2">19.94&#177;0.80</td>
			<td colspan="2">19.91&#177;0.41</td>
			<td>0.955</td>
		</tr>
		<tr>
			<td colspan="7">Spirometry</td>
		</tr>
		<tr>
			<td>&#160; FVC</td>
			<td>L</td>
			<td colspan="2">4.43&#177;0.26</td>
			<td colspan="2">3.13&#177;0.31</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td>&#160; FEV1</td>
			<td>L</td>
			<td colspan="2">3.70&#177;0.24</td>
			<td colspan="2">2.78&#177;0.23</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td>&#160; MVV</td>
			<td>L/min</td>
			<td colspan="2">131.78&#177;12.42</td>
			<td colspan="2">76.38&#177;13.57</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td>&#160; PEF</td>
			<td>L/s</td>
			<td colspan="2">8.96&#177;1.11</td>
			<td colspan="2">5.95&#177;1.41</td>
			<td>0.060</td>
		</tr>
		<tr>
			<td colspan="7">Notes: Significant results are indicated in bold. FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; MVV, maximum voluntary ventilation. PEF, peak expiratory flow; L, liter; s, second.</td>
		</tr>
	</tbody>
</table>
Table 1: Baseline characteristics and spirometry results.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td rowspan="2">Parameters</td>
			<td rowspan="2">Unit</td>
			<td colspan="3">Male group</td>
			<td></td>
			<td colspan="3">Female group</td>
		</tr>
		<tr>
			<td>Mask-off</td>
			<td>Mask-on</td>
			<td>P value</td>
			<td></td>
			<td>Mask-off</td>
			<td>Mask-on</td>
			<td>P value</td>
		</tr>
		<tr>
			<td colspan="3">Exercise tolerance and cardiac function</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160; VO2/kg (peak)</td>
			<td>(mL/min)/kg</td>
			<td>36.21&#177;3.8</td>
			<td>28.46&#177;4.96</td>
			<td>0.063</td>
			<td></td>
			<td>26.86&#177;4.86</td>
			<td>22.96&#177;5.45</td>
			<td>0.002</td>
		</tr>
		<tr>
			<td>&#160; VO2/kg (LT)</td>
			<td>(mL/min)/kg</td>
			<td>22.66&#177;2.26</td>
			<td>19.74&#177;2.23</td>
			<td>&#60;0.001</td>
			<td></td>
			<td>18.48&#177;2.89</td>
			<td>14.28&#177;2.6</td>
			<td>0.026</td>
		</tr>
		<tr>
			<td>&#160; O2/HR (peak)</td>
			<td>ratio</td>
			<td>12.14&#177;0.63</td>
			<td>10.02&#177;1.7</td>
			<td>0.028</td>
			<td></td>
			<td>7.96&#177;0.87</td>
			<td>6.9&#177;1.15</td>
			<td>0.004</td>
		</tr>
		<tr>
			<td>&#160; &#916;VO2/&#916;WR</td>
			<td>mL/(min*W)</td>
			<td>8.96&#177;0.3</td>
			<td>7.52&#177;1.4</td>
			<td>0.083</td>
			<td></td>
			<td>8.66&#177;0.51</td>
			<td>7.86&#177;1.17</td>
			<td>0.217</td>
		</tr>
		<tr>
			<td>&#160; HR (rest)</td>
			<td>bpm</td>
			<td>85.2&#177;16.08</td>
			<td>77.6&#177;7.09</td>
			<td>0.244</td>
			<td></td>
			<td>84&#177;10.56</td>
			<td>83.4&#177;5.94</td>
			<td>1.000</td>
		</tr>
		<tr>
			<td>&#160; HR (peak)</td>
			<td>bpm</td>
			<td>177.6&#177;10.5</td>
			<td>170.6&#177;11.33</td>
			<td>0.007</td>
			<td></td>
			<td>162.6&#177;17.67</td>
			<td>162.6&#177;21.72</td>
			<td>1.000</td>
		</tr>
		<tr>
			<td colspan="2">Ventilatory function</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160; VT (peak)</td>
			<td>L/min</td>
			<td>2.23&#177;0.31</td>
			<td>1.9&#177;0.4</td>
			<td>0.004</td>
			<td></td>
			<td>1.33&#177;0.28</td>
			<td>1.21&#177;0.28</td>
			<td>0.018</td>
		</tr>
		<tr>
			<td>&#160; BR%</td>
			<td>%</td>
			<td>50.2&#177;8.14</td>
			<td>56.6&#177;10.53</td>
			<td>0.086</td>
			<td></td>
			<td>53.6&#177;8.91</td>
			<td>57.8&#177;10.94</td>
			<td>0.086</td>
		</tr>
		<tr>
			<td>Gas exchange&#160;</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160; VE/VCO2&#160;</td>
			<td>ratio</td>
			<td>28.64&#177;3.42</td>
			<td>30.44&#177;5.26</td>
			<td>0.379</td>
			<td></td>
			<td>32.34&#177;3.63</td>
			<td>31.54&#177;4.3</td>
			<td>0.616</td>
		</tr>
		<tr>
			<td>&#160; VE (peak)</td>
			<td>L</td>
			<td>74&#177;13.36</td>
			<td>62.6&#177;15.35</td>
			<td>0.022</td>
			<td></td>
			<td>51.8&#177;13.35</td>
			<td>43.22&#177;11.72</td>
			<td>0.042</td>
		</tr>
		<tr>
			<td colspan="2">CPET performance</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160; Loadmax&#160;</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160; Loadmax (LT)</td>
			<td>watts</td>
			<td>98.2&#177;18.38</td>
			<td>102&#177;11.81</td>
			<td>0.438</td>
			<td></td>
			<td>56.8&#177;11.48</td>
			<td>50.8&#177;9.96</td>
			<td>0.104</td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160; Loadmax (RC)</td>
			<td>watts</td>
			<td>155.6&#177;22.47</td>
			<td>159&#177;24.37</td>
			<td>0.223</td>
			<td></td>
			<td>87.8&#177;18.47</td>
			<td>86.2&#177;19.6</td>
			<td>0.816</td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160; Loadmax (Peak)</td>
			<td>watts</td>
			<td>187&#177;28.15</td>
			<td>184.8&#177;26.81</td>
			<td>0.604</td>
			<td></td>
			<td>107.6&#177;29.25</td>
			<td>105.6&#177;30</td>
			<td>0.116</td>
		</tr>
		<tr>
			<td>&#160; RPE scale</td>
			<td>scores</td>
			<td>17.8&#177;0.84</td>
			<td>17&#177;1.73</td>
			<td>0.371</td>
			<td></td>
			<td>17.4&#177;0.89</td>
			<td>17.2&#177;1.3</td>
			<td>1.000</td>
		</tr>
		<tr>
			<td>&#160; Borg&#8217;s scale</td>
			<td>scores</td>
			<td>4.2&#177;0.84</td>
			<td>4.8&#177;1.64</td>
			<td>0.468</td>
			<td></td>
			<td>4.8&#177;0.45</td>
			<td>4.8&#177;0.84</td>
			<td>1.000</td>
		</tr>
		<tr>
			<td colspan="9">Notes: Significant results are indicated in bold. VO2/kg (peak), peak oxygen uptake per kilogram; VO2/kg (LT), anaerobic threshold per kilogram; O2/HR, oxygen pulse; &#916;VO2/&#916;WR, oxygen uptake related to work rate; BR%, breathing reserve in percentage; VE, ventilation; VT, tidal volume; bpm, beat per minute. RPE scalse, Rating of Perceived Exertion scale; L, liter; min, minute.</td>
		</tr>
	</tbody>
</table>
Table 2: Results of the CPET in healthy young subjects wearing a surgical mask (mask-on) and not wearing a surgical mask (mask-off) depicted as mean &#177; standard deviation.

Watch this Scientific Journal Video about Effects of Surgical Masks on Cardiopulmonary Function in Healthy Subjects at JoVE.com

Effects of Surgical Masks on Cardiopulmonary Function in Healthy Subjects

We study the effect of surgical masks on cardiopulmonary function based on a cardiopulmonary exercise test (CPET). This study shows that surgical masks reduce cardiopulmonary exercise capacity and ventilation in healthy young subjects and wearing masks might affect aerobic exercise capacity more in female subjects than in male subjects.

We study the effect of surgical masks on cardiopulmonary function based on a cardiopulmonary exercise test (CPET). This study shows that surgical masks ...

effects-surgical-masks-on-cardiopulmonary-function-healthy

Nanyang Technological University

Research

JoVE Journal

Behavior

3.2K Views.  The Fifth Affiliated Hospital of Guangzhou Medical University. Het dragen van een masker in openbare ruimtes kan de verspreiding van de infectieziekte belemmeren door zowel de inademing van infectieuze druppeltjes als de daaropvolgende uitademing en verspreiding ervan te voorkomen. Er zijn echter weinig onderzoeken naar het effect van het dragen van een masker op de cardiopulmonale functie. Verschillende soorten maskers hebben verschillende effecten op het verhogen van de uitademingsweerstand en de inademingsweerstand.Tijdens een pandemie van luch...

Video: Effects of Surgical Masks on Cardiopulmonary Function in Healthy Subjects

Impact Assessment of Repeated Exposure of Organotypic 3D Bronchial and Nasal Tissue Culture Models to Whole Cigarette Smoke

Cigarette smoke (CS) has a major impact on lung biology and may result in the development of lung diseases such as chronic obstructive pulmonary disease or lung cancer. To understand the underlying mechanisms of disease development, it would be important to examine the impact of CS exposure directly on lung tissues. However, this approach is difficult to implement in epidemiological studies because lung tissue sampling is complex and invasive. Alternatively, tissue culture models can facilitate the assessment of exposure impacts on the lung tissue. Submerged 2D cell cultures, such as normal human bronchial epithelial (NHBE) cell cultures, have traditionally been used for this purpose. However, they cannot be exposed directly to smoke in a similar manner to the in vivo exposure situation. Recently developed 3D tissue culture models better reflect the in vivo situation because they can be cultured at the air-liquid interface (ALI). Their basal sides are immersed in the culture medium; whereas, their apical sides are exposed to air. Moreover, organotypic tissue cultures that contain different type of cells, better represent the physiology of the tissue in vivo. In this work, the utilization of an in vitro exposure system to expose human organotypic bronchial and nasal tissue models to mainstream CS is demonstrated. Ciliary beating frequency and the activity of cytochrome P450s (CYP) 1A1/1B1 were measured to assess functional impacts of CS on the tissues. Furthermore, to examine CS-induced alterations at the molecular level, gene expression profiles were generated from the tissues following exposure. A slight increase in CYP1A1/1B1 activity was observed in CS-exposed tissues compared with air-exposed tissues. A network-and transcriptomics-based systems biology approach was sufficiently robust to demonstrate CS-induced alterations of xenobiotic metabolism that were similar to those observed in the bronchial and nasal epithelial cells obtained from smokers.

The aim of this protocol is to expose human organotypic 3D bronchial and nasal tissue models to mainstream cigarette smoke (CS) at the air-liquid interface. The impact of CS on the tissues is then investigated using a cytochrome P450 activity assay, a cilia beating measurement, and a systems biology approach.

Cigarette smoke (CS) has a major impact on lung biology and may result in the development of lung diseases such as chronic obstructive pulmonary disease ...

Bioengineering

Home-Based Prescribed Pulmonary Exercise in Patients with Stable Chronic Obstructive Pulmonary Disease

As a systemic disease, chronic obstructive pulmonary disease (COPD) affects the respiratory system, inducing restless and exercise dyspnea. It also impacts exercise capacity and forms a vicious circle in which it further aggravates the condition of patients and accelerates disease progression. As a functional holistic exercise, traditional Chinese exercises (TCE) play an important role in the rehabilitation of COPD on the basis of adjusting the breath and performing coordinated movements. This study investigates the effects of prescribed pulmonary exercises (which are modified from TCE) on exercise capacity of upper and lower limbs, endurance exercise capacity, and quality of life in stable COPD patients. The goal is to determine the accessibility of these prescribed exercises in COPD rehabilitation. Participants are randomly divided into a non-exercise control group (CG) or prescribed pulmonary exercise group (PG) at a ratio of 1: 1. The PG receives intervention for 60 min twice per day, 7 days a week, for a total of 3 months. The intensity is measured using the Borg category-ratio 10 scale and with a heart-rate monitor. Then, an exercise capacity test and quality of life questionnaire are scheduled at 1 week before and after the formal intervention. After 3 months of intervention, the 30 s arm curl test, 30 s sit-to-stand test, 6 min walking test, and quality of life show significant improvement in COPD patients (p &#60; 0.05). These findings indicate that prescribed pulmonary exercises can be applied as alternative, convenient, and effective home- and community-based exercises for stable COPD patients.

Presented here is a protocol to investigate the effects of home-based prescribed pulmonary exercise in stable chronic obstructive pulmonary disease (COPD) patients, which is modified based on traditional Chinese exercises according to dyspnea and limited exercise capacity observed in COPD patients.

As a systemic disease, chronic obstructive pulmonary disease (COPD) affects the respiratory system, inducing restless and exercise dyspnea. It also ...

Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early cardiopulmonary dysfunction is difficult to diagnose, particularly in animal models, as cardiopulmonary function is often measured invasively, requiring anesthesia. As many anesthetic agents are cardiodepressive, subtle changes in cardiovascular function may be masked. In contrast, chronic instrumentation allows for measurement of cardiopulmonary function in the awake state, so that measurements can be obtained under quiet resting conditions, without the effects of anesthesia and acute surgical trauma. Furthermore, when animals are properly trained, measurements can also be obtained during graded treadmill exercise.
Flow probes are placed around the aorta or pulmonary artery for measurement of cardiac output and around the left anterior descending coronary artery for measurement of coronary blood flow. Fluid-filled catheters are implanted in the aorta, pulmonary artery, left atrium, left ventricle and right ventricle for pressure measurement and blood sampling. In addition, a 20 G&#160;catheter is positioned in the anterior interventricular vein to allow coronary venous blood sampling.
After a week of recovery, swine are placed on a motor-driven treadmill, the catheters are connected to pressure and flow meters, and swine are subjected to a five-stage progressive exercise protocol, with each stage lasting 3 min. Hemodynamic signals are continuously recorded and blood samples are taken during the last 30 sec of each exercise stage.
The major advantage of studying chronically instrumented animals is that it allows serial assessment of cardiopulmonary function, not only at rest but also during physical stress such as exercise. Moreover, cardiopulmonary function can be assessed repeatedly during disease development and during chronic treatment, thereby increasing statistical power and hence limiting the number of animals required for a study.

Here we present a protocol to assess cardiopulmonary function in awake swine, at rest and during graded treadmill exercise. Chronic instrumentation allows for repeated hemodynamic measurements uninfluenced by cardiodepressive anesthetic agents.

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early ...

Medicine

A Recovery Cardiopulmonary Bypass Model Without Transfusion or Inotropic Agents in Rats

Cardiopulmonary bypass (CPB) is indispensable in cardiovascular surgery. Despite the dramatic refinement of CPB technique and devices, multi-organ complications related to prolonged CPB still compromise the outcome of cardiovascular surgeries, and may worsen postoperative morbidity and mortality. Animal models recapitulating the clinical usage of CPB enable the clarification of the pathophysiological processes that occur during CPB, and facilitate pre-clinical studies to develop strategies protecting against these complications. Rat CPB models are advantageous because of their greater cost-effectiveness, convenient experimental processes, abundant testing methods at the genetic or protein levels, and genetic consistency. They can be used for investigating the immune system activation and synthesis of proinflammatory cytokines, compliment activation, and production of oxygen free radicals. The rat models have been refined and have gradually taken the place of large-animal models. Here, we describe a simple CPB model without transfusion and/or inotropic agents in a rat. This recovery model allows the study of the long-term multiple organ sequelae of CPB.

Here, we present a protocol to describe a simple recovery cardiopulmonary bypass model without transfusion or inotropic agents in a rat. This model allows the study of the long-term multiple organ sequelae of cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) is indispensable in cardiovascular surgery. Despite the dramatic refinement of CPB technique and devices, multi-organ ...

Immunology and Infection

Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise

Exercise is a stress to the pulmonary vasculature. With incremental exercise, the pulmonary diffusing capacity (DLCO) must increase to meet the increased oxygen demand; otherwise, a diffusion limitation may occur. The increase in DLCO with exercise is due to increased capillary blood volume (Vc) and membrane diffusing capacity (Dm). Vc and Dm increase secondary to the recruitment and distension of pulmonary capillaries, increasing the surface area for gas exchange and decreasing pulmonary vascular resistance, thereby attenuating the increase in pulmonary arterial pressure. At the same time, the recruitment of intrapulmonary arteriovenous anastomoses (IPAVA) during exercise may contribute to gas exchange impairment and/or prevent large increases in pulmonary artery pressure.
We describe two techniques to evaluate pulmonary diffusion and circulation at rest and during exercise. The first technique uses multiple-fraction of inspired oxygen (FIO2) DLCO breath holds to determine Vc and Dm at rest and during exercise. Additionally, echocardiography with intravenous agitated saline contrast is used to assess IPAVAs recruitment.
Representative data showed that the DLCO, Vc, and Dm increased with exercise intensity. Echocardiographic data showed no IPAVA recruitment at rest, while contrast bubbles were seen in the left ventricle with exercise, suggesting exercise-induced IPAVA recruitment.
The evaluation of pulmonary capillary blood volume, membrane diffusing capacity, and IPAVA recruitment using echocardiographic methods is useful to characterize the ability of the lung vasculature to adapt to the stress of exercise in health as well as in diseased groups, such as those with pulmonary arterial hypertension and chronic obstructive pulmonary disease.

To assess the pulmonary diffusion and vasculature responses to exercise, we describe the multiple-inspired oxygen diffusion capacity technique to determine capillary blood volume and membrane diffusing capacity, as well as agitated saline contrast echocardiography to assess the recruitment of intrapulmonary arteriovenous anastomoses.

Exercise is a stress to the pulmonary vasculature. With incremental exercise, the pulmonary diffusing capacity (DLCO) must increase to meet the increased ...

Assessment of Respiratory Function in Conscious Mice by Double-chamber Plethysmography

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to non-invasively assess some features of the respiratory function in humans as well as in laboratory animals. The present article focuses on the application of the double-chamber plethysmography (DCP) in small animals. It provides background information on the methodology as well as a detailed step-by-step procedure to successfully assess respiratory function in conscious, spontaneously breathing animals in a non-invasive manner. The DCP can be used to monitor the respiratory function of multiple animals in parallel, as well as to identify changes induced by aerosolized substances over a chosen time period and in a repeated manner. Experiments on control and allergic mice are used herein to demonstrate the utility of the technique, explain the associated outcome parameters, as well as to discuss the related advantages and shortcomings. Overall, the DCP provides valid and theoretically sound readouts that can be trusted to evaluate the respiratory function of conscious small animals both at baseline and after challenges with aerosolized substances.

The objective of the present article is to provide a detailed description of the recommended procedures to evaluate respiratory function in conscious mice by double-chamber plethysmography.

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to ...

Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular (LV) filling compared with a continuous linear jet. Vortex ring development is most often quantified with vortex formation time (VFT), a dimensionless parameter based on fluid ejection from a rigid tube. Our group is interested in factors that affect LV filling efficiency during cardiac surgery. In this report, we describe how to use standard two-dimensional (2D) and Doppler transesophageal echocardiography (TEE) to noninvasively derive the variables needed to calculate VFT. We calculate atrial filling fraction (&#946;) from velocity-time integrals of trans-mitral early LV filling and atrial systole blood flow velocity waveforms measured in the mid-esophageal four-chamber TEE view. Stroke volume (SV) is calculated as the product of the diameter of the LV outflow track measured in the mid-esophageal long axis TEE view and the velocity-time integral of blood flow through the outflow track determined in the deep transgastric view using pulse-wave Doppler. Finally, mitral valve diameter (D) is determined as the average of major and minor axis lengths measured in orthogonal mid-esophageal bicommissural and long axis imaging planes, respectively. VFT is then calculated as 4 &#215; (1-&#946;) &#215; SV/(&#960;D3). We have used this technique to analyze VFT in several groups of patients with differing cardiac abnormalities. We discuss our application of this technique and its potential limitations and also review our results to date. Noninvasive measurement of VFT using TEE is straightforward in anesthetized patients undergoing cardiac surgery. The technique may allow cardiac anesthesiologists and surgeons to assess the impact of pathological conditions and surgical interventions on LV filling efficiency in real time.

We describe a protocol to measure vortex formation time, an index of left ventricular filling efficiency, using standard transesophageal echocardiography techniques in patients undergoing cardiac surgery. We apply this technique to analyze vortex formation time in several groups of patients with differing cardiac pathologies.

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular ...

Integration of Brain Tissue Saturation Monitoring in Cardiopulmonary Exercise Testing in Patients with Heart Failure

Cerebral hypo-oxygenation during rest or exercise negatively impacts the exercise capacity of patients with heart failure with reduced ejection fraction (HF). However, in clinical cardiopulmonary exercise testing (CPET), cerebral hemodynamics is not assessed. NIRS is used to measure cerebral tissue oxygen saturation (SctO2) in the frontal lobe. This method is reliable and valid and has been utilized in several studies. SctO2 is lower during both rest and peak exercise in patients with HF than in healthy controls (66.3 &#177; 13.3% and 63.4 &#177; 13.8% vs. 73.1 &#177; 2.8% and 72 &#177; 3.2%). SctO2 at rest is significantly linearly correlated with peak VO2 (r = 0.602), oxygen uptake efficiency slope (r = 0.501), and brain natriuretic peptide (r = -0.492), all of which are recognized prognostic and disease severity markers, indicating its potential prognostic value. SctO2 is determined mainly by end-tidal CO2 pressure, mean arterial pressure, and hemoglobin in the HF population. This article demonstrates a protocol that integrates SctO2 using NIRS into incremental CPET on a calibrated bicycle ergometer.

This protocol integrated near-infrared spectroscopy into conventional cardiopulmonary exercise testing to identify the involvement of the cerebral hemodynamic response in exercise intolerance in patients with heart failure.

Cerebral hypo-oxygenation during rest or exercise negatively impacts the exercise capacity of patients with heart failure with reduced ejection fraction ...

Conducting Respiratory Oscillometry in an Outpatient Setting

Respiratory oscillometry is a different modality of pulmonary function testing that is increasingly used in a clinical and research setting to provide information regarding lung mechanics. Respiratory oscillometry is conducted through three acceptable measurements of tidal breathing and can be performed with minimal contraindications. Young children and patients who cannot perform spirometry due to cognitive or physical impairment can usually complete oscillometry. The main advantages of respiratory oscillometry are that it requires minimal patient cooperation and is more sensitive in detecting changes in small airways than conventional pulmonary function tests. Commercial devices are now available. Updated technical guidelines, standard operating protocols, and quality control/assurance guidelines have recently been published. Reference values are also available. 
We conducted oscillometry test audits before and after implementing a formal respiratory oscillometry training program and standard operating protocol. We observed improvement in the quality of tests completed, with a significant increase in the number of acceptable and reproducible measurements. 
The current paper outlines and demonstrates a standard operating protocol to conduct respiratory oscillometry in an outpatient setting. We highlight the key steps to ensuring acceptable and reproducible quality measurements according to the recommended European Respiratory Society (ERS) guidelines, as quality control is critical to measurement accuracies. Potential problems and pitfalls are also discussed with suggestions to resolve technical errors.

We demonstrate a standard operating protocol to conduct respiratory oscillometry, highlighting key quality control and assurance procedures.

Respiratory oscillometry is a different modality of pulmonary function testing that is increasingly used in a clinical and research setting to provide ...

Oxygenation-sensitive Cardiac MRI with Vasoactive Breathing Maneuvers for the Non-invasive Assessment of Coronary Microvascular Dysfunction

Oxygenation-sensitive cardiac magnetic resonance imaging (OS-CMR) is a diagnostic technique that uses the inherent paramagnetic properties of deoxyhemoglobin as an endogenous source of tissue contrast. Used in combination with standardized vasoactive breathing maneuvers (hyperventilation and apnea) as a potent non-pharmacologic vasomotor stimulus, OS-CMR can monitor changes in myocardial oxygenation. Quantifying such changes during the cardiac cycle and throughout vasoactive maneuvers can provide markers for coronary macro- and microvascular function and thereby circumvent the need for any extrinsic, intravenous contrast or pharmacologic stress agents.
OS-CMR uses the well-known sensitivity of T2*-weighted images to blood oxygenation. Oxygenation-sensitive images can be acquired on any cardiac MRI scanner using a modified standard clinical steady-state free precession (SSFP) cine sequence, making this technique vendor-agnostic and easily implemented. As a vasoactive breathing maneuver, we apply a 4-min breathing protocol of 120 s of free breathing, 60 s of paced hyperventilation, followed by an expiratory breath-hold of at least 30 s. The regional and global response of myocardial tissue oxygenation to this maneuver can be assessed by tracking the signal intensity change. The change over the initial 30 s of the post-hyperventilation breath-hold, referred to as the breathing-induced myocardial oxygenation reserve (B-MORE) has been studied in healthy people and various pathologies. A detailed protocol for performing oxygen-sensitive CMR scans with vasoactive maneuvers is provided.
As demonstrated in patients with microvascular dysfunction in yet incompletely understood conditions, such as inducible ischemia with no obstructive coronary artery stenosis (INOCA), heart failure with preserved ejection fraction (HFpEF), or microvascular dysfunction after heart transplantation, this approach provides unique, clinically important, and complementary information on coronary vascular function.

The assessment of microvascular function by oxygenation-sensitive cardiac magnetic resonance imaging in combination with vasoactive breathing maneuvers is unique in its ability to assess rapid dynamic changes in myocardial oxygenation in vivo and, thus, may serve as a critically important diagnostic technique for coronary vascular function.

Effects of Surgical Masks on Cardiopulmonary Function in Healthy Subjects

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