Baseline values of cardiovascular and respiratory parameters predict response to acute hypoxia in young healthy men

Potential adverse effects of face mask use on cardiopulmonary function and thermoregulation in robotic stroke rehabilitation during the COVID-19 pandemic

BACKGROUND

The coronavirus disease (COVID-19) pandemic led to the implementation of wearing face masks and social distancing in stroke rehabilitation to prevent airborne transmission and contain the virus. The use of masks causes hypoxia and dyspnea in patients with stroke, predisposing them to other harmful medical conditions. Despite the clinical importance of the potential risk of wearing masks during robotic stroke rehabilitation, no clinical evidence is available in the literature.

OBJECTIVE

To examine the effects of stroke robotic rehabilitation with and without using a face mask on cardiopulmonary fatigue, muscle fatigue, O2 saturation, pulse, blood pressure (BP), and temperature in healthy adults and patients with hemiparetic stroke.

METHOD

A total of 30 participants, comprising 20 males and 10 females, were enrolled in a case-control study and a cross-sectional randomized controlled trial conducted at the Center for Rehabilitation Hospital. The study population included 15 individuals with hemiparetic stroke (mean age: 57.26±8.69) and 15 healthy adult controls (mean age: 30.20±9.86). All participants underwent a 30-minute familiarization session, followed by experimental masked and unmasked robotic interactive gait training (RIGT) for at least 30 minutes. Clinical tests included the Borg Rating of Perceived Exertion, muscle fatigue via surface electromyography, O2 saturation, pulse, BP, and temperature.

RESULTS

An analysis of covariance showed that compared to RIGT without a mask, RIGT with a mask showed adverse effects on BRPE, O2 saturation, and right rectus femoris muscle fatigue (P < 0.05) in the control and experimental groups.

CONCLUSION

The clinical study revealed that compared to RIGT without a mask, RIGT with a mask affected cardiopulmonary fatigue, muscle fatigue, O2 saturation, pulse, and BP in healthy adults and participants with hemiparetic stroke.

Effects of High-Intensity Exercise on Physiological Indicators of Recovery Period by Wearing Face Masks of Elite Athletes

Athletes need to maintain the necessary physical conditioning for sports performance while wearing face masks to reduce the risk of virus transmission during training and competition during the COVID-19 situation. The quantitative and physiological effects of face masks on exercise capacity needs to be reported. The purpose of this study was to evaluate elite athletes to quantify, in detail, the effect of a KF94 face mask on changes in lactic acid during recovery after high-intensity aerobic exercise. Thirteen elite soft tennis athletes were recruited. A crossover design was used to examine the effects of using a disposable KF94 face mask compared with not masking during exercise. The participants completed a shuttle run test experiment two times during a 3-day period, including 5−10 min of warmup according to their personal preferences. The lactic acid concentration at 20 min of recovery after maximum exercise was 5.98 ± 1.53 mM/L without a mask and 7.61 ± 1.85 mM/L with a KF94 mask (p < 0.001). The maximum laps of shuttle run tests were 101.5 ± 22.5 laps without a mask and 94.2 ± 20.2 laps with a KF94 mask (p < 0.001). Intense exercise after wearing quarantine masks reduces the maximum aerobic exercise ability and decreases the ability to recover lactic acid.

Maximal exercise outcomes with a face mask: the effects of gender and age differences on cardiorespiratory responses

Background

Surgical masks have become an important accessory of physical activity in daily life due to the COVID-19 pandemic.

Aims

To determine the effects of the surgical mask on respiratory gas exchange parameters, dyspnoea, and hemodynamic responses during maximal exercise in different age groups and gender.

Methods

Twenty-six healthy participants between 18 and 65 years (mean 37.35 ± 15.99) performed a maximal exercise test twice randomly, with and without a mask. To determine the respiratory gas exchange parameters (peak oxygen consumption (VO_2peak), minute ventilation (V_E), energy expenditure (EE), respiratory rate), and hemodynamic responses, each participant underwent a maximal exercise test with Bruce protocol on the treadmill. The modified Borg scale (MBS) was used to determine the dyspnoea before and after exercise test.

Results

Test duration (min), metabolic equivalents (MET), VO2_peak ml/kg/min, respiratory rate, and peak heart rate (HR_peak) of young participants after exercise test with and without a mask were higher than in middle-aged participants (p < 0.01). There was no significant difference between males and females in test duration, VO_2peak ml/kg/min, VO_2peak ml/min, MET, V_E l/min, respiratory rate, MBS, and EE in masked tests (p > 0.05).

Conclusion

The surgical mask use affected the maximal exercise capacity of middle-aged participants more than young participants. Although males performed better than females in tests without masks, the decrease in exercise capacity with mask use was greater than in females. Advanced age and male gender may be factors that need more attention during exercise with mask use.

Trial registration number and date

NCT04498546—02/17/2021.

The Effect of Surgical Mask Use in Anaerobic Running Performance

COVID-19 restrictions stipulate the mandatory use of surgical masks during outdoor and indoor physical activities. The impact of this on athletic performance and especially on anaerobic physical activities is poorly known. The aim of the present research was to analyze the effect of surgical mask use on the anaerobic running performance of athletes. Modifications in running time, blood lactate, blood glucose, blood oxygen saturation, subjective perceived stress, rating of perceived exertion, and heart rate variability were measured in 50 m and 400 m maximal running tests with and without the use of surgical masks in 72 athletes. The use of a surgical mask increased blood lactate concentration, sympathetic autonomic modulation, perceived exertion, perceived stress, and decreased blood oxygen saturation in 50 and 400 m running tests. Thus, the higher levels of blood lactate and lower blood oxygen saturation require adaptation of the athlete’s rest and recovery periods to the acute workload. The higher level of sympathetic activation makes the acute and chronic control of autonomic modulation essential for an efficient training periodization. Finally, the use of acid buffers such as bicarbonate or sodium citrate would be a recommended ergogenic strategy.

Cognitive and psychophysiological impact of surgical mask use during university lessons

The aim of the present study was to analyze the impact of surgical mask use in cognitive and psychophysiological response of university students during a lesson. We analyzed 50 volunteers university students (age 20.2 ± 2.9) in two 150 min lessons. i. personal class using a surgical mask and ii. online class with student at home without the mask. Blood oxygen saturation, heart rate and heart rate variability, mental fatigue and reaction time were measured before and immediately after both lectures. We found how both lesson produced an increase in mental fatigue, reaction time and autonomous sympathetic modulation, being heart rate significantly higher (77.7 ± 18.2 vs. 89.3 ± 11.2 bpm, not mask, mask respectively) and blood oxygen saturation significantly lower (98.4 ± 0.5 vs. 96.0 ± 1.8%, mask, not mask respectively) using the surgical mask. The use of surgical mask during a 150 min university lesson produced an increased heart rate and a decrease in blood oxygen saturation, not significantly affecting the mental fatigue perception, reaction time and time, frequency and nonlinear hear rate variability domains of students.

Some Immunological Impacts of Face Mask Usage During the COVID-19 Pandemic

&lt;b&gt;Background and Objective:&lt;/b&gt; COVID-19 is a fast-spreading worldwide pandemic caused by SARS-CoV-2. The World Health Organization recommended wearing face masks. Masks have become an urgent necessity throughout the pandemic, the study's goal was to track the impact of wearing masks on immunological responses. &lt;b&gt;Materials and Methods:&lt;/b&gt; This study was conducted on 40 healthy people who were working in health care at Nineveh Governorate Hospitals from September-December, 2020. They wore face masks at work for more than 8 months for an average of 6 hrs a day. The control sample included 40 healthy individuals, who wore masks for very short periods. All samples underwent immunological and physiological tests to research the effects of wearing masks for extended periods within these parameters. &lt;b&gt;Results:&lt;/b&gt; The results showed a significant decrease in total White Blood Count and the absolute number of neutrophils, lymphocytes, monocytes and phagocytic activity. However, there was a significant increase in the absolute number of eosinophils in participants compared with the control. The results also suggested there were no significant differences in IgE, haemoglobin concentration and blood O&lt;sub&gt;2 &lt;/sub&gt;saturation in participants who wore masks for more than 6 hrs compared to the control group. The results showed a significant increase in pulse rate in participants who wore masks for more than 6 hrs compared to the control group. The results also showed a strong correlation coefficient between the time of wearing masks and some immunological, haematological parameters. &lt;b&gt;Conclusion:&lt;/b&gt; Wearing masks for long periods alters immunological parameters that initiate the immune response, making the body weaker in its resistance to infectious agents.

COVID-19: Electrophysiological mechanisms underlying sudden cardiac death during exercise with facemasks

The mandatory use of facemasks is a public health measure implemented by various countries in response to the novel coronavirus disease 19 (COVID-19) pandemic. However, there have been case reports of sudden cardiac death (SCD) with the wearing of facemasks during exercise. In this paper, we hypothesize that exercise with facemasks may increase the risk of ventricular tachycardia/ventricular fibrillation (VT/VF) leading to SCD via the development of acute and/or intermittent hypoxia and hypercapnia. We discuss the potential underlying mechanisms including increases in adrenergic stimulation and oxidative stress leading to electrophysiological abnormalities that promote arrhythmias via non-reentrant and reentrant mechanisms. Given the interplay of multiple variables contributing to the increased arrhythmic risk, we advise avoidance of a facemask during high intensity exercise, or if wearing of a mask is mandatory, exercise intensity should remain low to avoid precipitation of lethal arrhythmias. However, we cannot exclude the possibility of an arrhythmic substrate even with low intensity exercise especially in those with established chronic cardiovascular disease in whom baseline electrophysiological abnormalities may be found.

Effect of Acute Hypoxia on Cardiorespiratory Coherence in Male Runners

Understanding the mechanisms of oxygen supply regulation, which involves the respiratory and cardiovascular systems, during human adaptation to intense physical activity, accompanied by hypoxemia, is important for the management of a training process. The objectives of this study were to investigate the cardiorespiratory coherence (CRC) changes in the low-frequency band in response to hypoxic exposure and to verify a dependence of these changes upon sports qualification level in athletes. Twenty male runners aged 17-25 years were exposed to acute normobaric hypoxia (10% O2) for 10 min. Respiration, gas exchange, and heart rate were measured at baseline, during hypoxia, and after the exposure. To evaluate cardiorespiratory coupling, squared coherence was calculated based on 5-s averaged time series of heart and respiratory rhythms. Based on sports qualification level achieved over 4 years after the experimental testing, athletes were retrospectively divided into two groups, one high level (HLG, n = 10) and the other middle level (MLG, n = 10). No differences in anthropometric traits were observed between the groups. In the pooled group, acute hypoxia significantly increased CRC at frequencies 0.030-0.045 Hz and 0.075 Hz. In response to hypoxia, oxygen consumption decreased in HLG, and carbon dioxide production and ventilation increased in MLG. At 0.070-0.080 Hz frequencies in hypoxia, the CRC in HLG was higher than in MLG. Thus, highly qualified athletes enhance intersystem integration in response to hypoxia. This finding can be a physiological sign for the prognosis of qualification level in runners.

"Exercise with facemask; Are we handling a devil's sword?" - A physiological hypothesis

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The study demonstrates potential complications associated with facemasks during exercises.

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N95 respirators induces acidic environment which in turn affects the immune and metabolic systems.

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Facemasks during exercise may exacerbate the pathology of underlying chronic diseases.

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Further depression, anxiety induced by poor oxygenation and vasodilatory status when exercising with facemasks.

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The social exercisers should socially distance during exercise rather than wearing masks.

Straying away from a sedentary lifestyle is essential, especially in these troubled times of a global pandemic to reverse the ill effects associated with the health risks as mentioned earlier. In the view of anticipated effects on immune system and prevention against influenza and Covid-19, globally moderate to vigorous exercises are advocated wearing protective equipment such as facemasks. Though WHO supports facemasks only for Covid-19 patients, healthy “social exercisers” too exercise strenuously with customized facemasks or N95 which hypothesized to pose more significant health risks and tax various physiological systems especially pulmonary, circulatory and immune systems. Exercising with facemasks may reduce available Oxygen and increase air trapping preventing substantial carbon dioxide exchange. The hypercapnic hypoxia may potentially increase acidic environment, cardiac overload, anaerobic metabolism and renal overload, which may substantially aggravate the underlying pathology of established chronic diseases. Further contrary to the earlier thought, no evidence exists to claim the facemasks during exercise offer additional protection from the droplet transfer of the virus. Hence, we recommend social distancing is better than facemasks during exercise and optimal utilization rather than exploitation of facemasks during exercise.

Testing individual baroreflex responses to hypoxia-induced peripheral chemoreflex stimulation

Introduction

Baroreflexes and peripheral chemoreflexes control efferent autonomic activity making these reflexes treatment targets for arterial hypertension. The literature on their interaction is controversial, with suggestions that their individual and collective influence on blood pressure and heart rate regulation is variable. Therefore, we applied a study design that allows the elucidation of individual baroreflex–chemoreflex interactions.

Methods

We studied nine healthy young men who breathed either normal air (normoxia) or an air–nitrogen–carbon dioxide mixture with decreased oxygen content (hypoxia) for 90 min, with randomization to condition, followed by a 30-min recovery period and then exposure to the other condition for 90 min. Multiple intravenous phenylephrine bolus doses were applied per condition to determine phenylephrine pressor sensitivity as an estimate of baroreflex blood pressure buffering and cardiovagal baroreflex sensitivity (BRS).

Results

Hypoxia reduced arterial oxygen saturation from 98.1 ± 0.4 to 81.0 ± 0.4% (p < 0.001), raised heart rate from 62.9 ± 2.1 to 76.0 ± 3.6 bpm (p < 0.001), but did not change systolic blood pressure (p = 0.182). Of the nine subjects, six had significantly lower BRS in hypoxia (p < 0.05), two showed a significantly decreased pressor response, and three showed a significantly increased pressor response to phenylephrine in hypoxia, likely through reduced baroreflex buffering (p < 0.05). On average, hypoxia decreased BRS by 6.4 ± 0.9 ms/mmHg (19.9 ± 2.0 vs. 14.12 ± 1.6 ms/mmHg; p < 0.001) but did not change the phenylephrine pressor response (p = 0.878).

Conclusion

We applied an approach to assess individual baroreflex–chemoreflex interactions in human subjects. A subgroup exhibited significant impairments in baroreflex blood pressure buffering and BRS with peripheral chemoreflex activation. The methodology may have utility in elucidating individual pathophysiology and in targeting treatments modulating baroreflex or chemoreflex function.

Physiological Effects of N95 FFP and PPE in Healthcare Workers in COVID Intensive Care Unit: A Prospective Cohort Study

Background

Healthcare workers (HCWs) are at increased risk of exposure to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Personal protective equipment (PPE) is mandated for HCWs. However, the physiological effects on the HCWs while working in the protective gear remains unexplored. This study aimed to assess the physiological effects of the prolonged use of PPE on HCWs.

Materials and methods

Seventy-five HCWs, aged 18–50 years were enrolled in this prospective, observational, cohort study. The physiological variables [heart rate, oxygen saturation, and perfusion index (PI)] were recorded at the start of duty, 4 hours after wearing N95 filtering facepiece respirator (FFR), pre-donning, and post-doffing. The rating of perceived exertion (RPE) score and modified Borg scale for dyspnea was evaluated. The physiological variables were represented as the mean ± standard deviation. Wilcoxon signed-rank test was used to show any difference in RPE and modified Borg scale for dyspnea. A p value of <0.05 was considered significant.

Results

There is a statistically significant difference in the physiological parameters post-doffing compared with baseline: Heart rate (p < 0.001); oxygen saturation (p < 0.001); PI (p < 0.001). RPE score showed increased discomfort with continuous use of N95 FFR. However, exertion increased only marginally. The major adverse effects noted with PPE use were fogging, headache, tiredness, difficulty in breathing, and mask soakage, with a resultant mean duration of donning to be 3.1 hours.

Conclusion

The use of PPE can result in considerable changes in the physiological variables of healthy HCWs. The side effects may lead to excessive exhaustion and increased tiredness after prolonged shifts in the intensive care unit (ICU) while wearing PPE.

How to cite this article

Choudhury A, Singh M, Khurana DK, Mustafi SM, Ganapathy U, Kumar A, et al. Physiological Effects of N95 FFP and PPE in Healthcare Workers in COVID Intensive Care Unit: A Prospective Cohort Study. Indian J Crit Care Med 2020;24(12):1169–1173.

Effect of chronic intermittent hypobaric hypoxia on heart rate variability in conscious rats

To examine the effect of chronic intermittent hypobaric hypoxia (CIHH) on heart rate variability (HRV), male adult Sprague Dawley rats were exposed to hypoxia (oxygen 11.1%) in a hypobaric chamber for 42 days, 6 hours each day, simulating an altitude of 5000 m. The body weight and blood pressure of rats were recorded once a week, electrocardiograms were analyzed continuously using biotelemetry, before, during and after CIHH treatment each day, and HRV was evaluated using spectrum analysis. No significant difference of body weight and blood pressure was found between CIHH and control rats. After 4 weeks of CIHH treatment, total power (TP) and very low-frequency component (VLF) were lower in CIHH rats than in control rats under hypobaric hypoxia condition. During CIHH treatment, low frequency (LF) was higher in 1 week and lower in 5-6 weeks in CIHH rats than control rats under hypobaric hypoxia, but not normoxic conditions. The high-frequency component (HF) was not changed during CIHH treatment, so LF/HF increased initially, and then recovered under the hypobaric hypoxia condition following 3 weeks of CIHH treatment. In addition, the HR was increased in CIHH rats after 4 weeks of CIHH treatment compared with control rats. Furthermore, HRV was altered significantly in control rats, but not in CIHH rats exposed to acute normobaric hypoxia. These data suggest that CIHH treatment modulates cardiac autonomic activity adaptively and inhibits the acute normobaric hypoxia-induced changes in HRV.