Carbon Dioxide Physiological Training at NASA

Headache related to mask use of healthcare workers in COVID-19 pandemic

Background

It has been reported that a new type of headache may develop as a result of face mask use during the COVID-19 pandemic. The aim of this study is to investigate the clinical features of face mask-related headache during the COVID-19 pandemic.

Methods

This is a cross-sectional study carried out on healthcare workers at the Afyonkarahisar Health Sciences University. The number of workers at our university was established. Sample size was calculated using the G*Power program. A questionnaire consisting of questions relating to pre-existing headache, an aggravation in headache, and de-novo headache was filled out by 3 neurologists with all participants.

Results

Data was collected from a total of 375 participants, after the exclusion of 5 individuals who refused to participate. Out of all participants, 26 (6.9%) used a filtering mask, 274 (73.1%) used a surgical mask, 75 (20.0%) participants used a combination of both masks. The number of participants with preexisting headache was 114 (30.4%) had pre-existing headache. Of those with pre-existing headache, 77 (67.5%) healthcare workers had reported an aggravation in their headache after mask use. De-novo headache was observed in 116 (30.9%) of participants. De-novo headache characteristics included throbbing in 17 (14.7%) participants and pressing in 99 (85.3%) participants. In addition, symptoms such as tachypnea, sleep disturbance, and fatigue were found to be significantly higher.

Conclusions

This study indicates that healthcare workers develop headaches due to use of masks during the COVID-19 outbreak.

The use of personal protection equipment does not impair the quality of cardiopulmonary resuscitation: A prospective triple-cross over randomised controlled non-inferiority trial

AIM

Prior studies suggest that the use of personal protective equipment might impair the quality of critical care. We investigated the influence of personal protective equipment on out-of-hospital cardiopulmonary resuscitation.

METHODS

Randomised controlled non-inferiority triple-crossover study. Forty-eight emergency medical service providers, randomized into teams of two, performed 12 min of basic life support (BLS) on a manikin after climbing 3 flights of stairs. Three scenarios were completed in a randomised order: Without personal protective equipment, with personal protective equipment including a filtering face piece (FFP) 2 mask with valve, and with personal protective equipment including an FFP2 mask without valve. The primary outcome was mean depth of chest compressions with a pre-defined non-inferiority margin of 3.5 mm. Secondary outcomes included other measurements of CPR quality, providers' subjective exhaustion levels, and providers' vital signs, including end-tidal CO₂.

RESULTS

Differences regarding the primary outcome were well below the pre-defined non-inferiority margins for both control vs. personal protective equipment without valve (absolute difference 1 mm, 95% CI [-1, 2]) and control vs. personal protective equipment with valve (absolute difference 1 mm, [-0.2, 2]). This was also true for secondary outcomes regarding quality of chest compressions and providers' vital signs including etCO₂. Subjective physical strain after BLS was higher in the personal protective equipment groups (Borg 4 (SD 3) without valve, 4 (SD 2) with valve) than in the control group (Borg 3 (SD 2)).

CONCLUSION

PPE including masks with and without expiration valve is safe for use without concerns regarding the impairment of CPR quality.

[COVID-19 and Headaches]

COVID-19 and Headaches Abstract. Headaches are a common symptom of COVID-19 infections. Patients generally describe them as bilateral, predominantly frontal, squeezing and of moderate or severe intensity. Searching for "Red Flags" often allows distinction from primary headaches - usually fever, cough, and elevated inflammatory markers accompany COVID-19-associated headaches. Prospective studies did not confirm caveats against the use of ibuprofen as symptomatic treatment. While carrying facial masks often caused headaches, probably by compressing sensory nerves, many patients' migraine frequencies dropped during lockdown. Treatment of patients with primary headaches was complicated by quarantine and many centres offered online consultations.

Mask-associated 'de novo' headache in healthcare workers during the COVID-19 pandemic

OBJECTIVES

The pandemic caused by the new coronavirus (COVID-19) has changed care activities of health professionals. We analysed the possible association between the appearance of 'de novo' headache according to the type of mask used, the related factors and the impact of the cephalalgia on health professionals.

METHODS

Cross-sectional study in a tertiary hospital in Extremadura, Spain. We provided an online questionnaire to healthcare workers during the period of maximum incidence of COVID-19 in our setting.

RESULTS

The subjects are n=306, 244 women (79.7%), with an average age of 43 years (range 23-65). Of the total, 129 (42.2%) were physicians, 112 (36.6%) nurses and 65 (21.2%) other health workers. 208 (79.7%) used surgical masks and 53 (20.3%) used filter masks. Of all those surveyed, 158 (51.6%) presented 'de novo' headache. The occurrence of a headache was independently associated with the use of a filter mask, OR 2.14 (95% CI 1.07 to 4.32); being a nurse, OR 2.09 (95% CI 1.18 to 3.72) or another health worker, OR 6.94 (95% CI 3.01 to 16.04); or having a history of asthma, OR 0.29 (95% CI 0.09 to 0.89). According to the type of mask used, there were differences in headache intensity, and the impact of a headache in the subjects who used a filter mask was worse in all the aspects evaluated.

CONCLUSION

The appearance of 'de novo' headache is associated with the use of filter masks and is more frequent in certain healthcare workers, causing a greater occupational, family, personal and social impact.

Acute Effects of Using Added Respiratory Dead Space Volume in a Cycling Sprint Interval Exercise Protocol: A Cross-Over Study

Background: The aim of the study was to compare acute physiological, biochemical, and perceptual responses during sprint interval exercise (SIE) with breathing through a device increasing added respiratory dead space volume (ARDS_V) and without the device. Methods: The study involved 11 healthy, physically active men (mean maximal oxygen uptake: 52.6 ± 8.2 mL∙kg¹∙min^-1). During four visits to a laboratory with a minimum interval of 72 h, they participated in (1) an incremental test on a cycle ergometer; (2) a familiarization session; (3) and (4) cross-over SIE sessions. SIE consisted of 6 × 10-s all-out bouts with 4-min active recovery. During one of the sessions the participants breathed through a 1200-mL ARDSv (SIE_ARDS). Results: The work performed was significantly higher by 4.4% during SIE_ARDS, with no differences in the fatigue index. The mean respiratory ventilation was significantly higher by 13.2%, and the mean oxygen uptake was higher by 31.3% during SIE_ARDS. Respiratory muscle strength did not change after the two SIE sessions. In SIE_ARDS, the mean pH turned out significantly lower (7.26 vs. 7.29), and the mean HCO₃^- concentration was higher by 7.6%. Average La^- and rating of perceived exertion (RPE) did not differ between the sessions. Conclusions: Using ARDS_V during SIE provokes respiratory acidosis, causes stronger acute physiological responses, and does not increase RPE.

Factors affecting flavor perception in space: Does the spacecraft environment influence food intake by astronauts?

The intention to send a crewed mission to Mars involves a huge amount of planning to ensure a safe and successful mission. Providing adequate amounts of food for the crew is a major task, but 20 years of feeding astronauts on the International Space Station (ISS) have resulted in a good knowledge base. A crucial observation from the ISS is that astronauts typically consume only 80% of their daily calorie requirements when in space. This is despite daily exercise regimes that keep energy usage at very similar levels to those found on Earth. This calorie deficit seems to have little effect on astronauts who spend up to 12 months on the ISS, but given that a mission to Mars would take 30 to 36 months to complete, there is concern that a calorie deficit over this period may lead to adverse effects in crew members. The key question is why astronauts undereat when they have a supply of food designed to fully deliver their nutritional needs. This review focuses on evidence from astronauts that foods taste different in space, compared to on Earth. The underlying hypothesis is that conditions in space may change the perceived flavor of the food, and this flavor change may, in turn, lead to underconsumption by astronauts. The key areas investigated in this review for their potential impact on food intake are the effects of food shelf life, physiological changes, noise, air and water quality on the perception of food flavor, as well as the link between food flavor and food intake.

Shallow metabolic depression and human spaceflight: a feasible first step

Synthetic torpor is an induced state of deep metabolic depression (MD) in an organism that does not naturally employ regulated and reversible MD. If applied to spaceflight crewmembers, this metabolic state may theoretically mitigate numerous biological and logistical challenges of human spaceflight. These benefits have been the focus of numerous recent articles where, invariably, they are discussed in the context of hypothetical deep MD states in which the metabolism of crewmembers is profoundly depressed relative to basal rates. However, inducing these deep MD states in humans, particularly humans aboard spacecraft, is currently impossible. Here, we discuss shallow MD as a feasible first step toward synthetic torpor during spaceflight and summarize perspectives following a recent NASA-hosted workshop. We discuss methods to safely induce shallow MD (e.g., sleep and slow wave enhancement via acoustic and photoperiod stimulation; moderate sedation via dexmedetomidine), which we define as an ~20% depression of metabolic rate relative to basal levels. We also discuss different modes of shallow MD application (e.g., habitual versus targeted, whereby shallow MD is induced routinely throughout a mission or only under certain circumstances, respectively) and different spaceflight scenarios that would benefit from its use. Finally, we propose a multistep development plan toward the application of synthetic torpor to human spaceflight, highlighting shallow MD's role. As space agencies develop missions to send humans further into space than ever before, shallow MD has the potential to confer health benefits for crewmembers, reduce demands on spacecraft capacities, and serve as a testbed for deeper MD technologies.

Cooling to Facilitate Metabolic Suppression in Healthy Individuals

BACKGROUND: Carbon dioxide (CO₂) toxicity could be catastrophic for astronauts. Suppressing metabolism by lowering body temperature decreases CO₂ production and may facilitate rescue in the event of a crippled ship. Lowering body temperature requires shivering suppression. We evaluated dexmedetomidine to facilitate cooling of healthy individuals.METHODS: Following consent, we administered a 1 mcg · kg^-1 bolus of dexmedetomidine followed by continuous infusion (0.5-1.4 mcg · kg^-1 · h^-1) for 3 h of cooling. We cooled subjects using a bolus of 30 cc · kg^-1 of 4°C saline followed by surface cooling. We measured vital signs, thermal and comfort scales, sedation, and shivering for 3 h and during recovery. ANOVA evaluated changes in measures over time.RESULTS: Nine subjects completed the study. Mean age was 31 (SD 8) yr, mean mass was 71 (SD 14) kg, height of 168 (SD 9) cm, and body mass index of 25 (SD 3). Median time to 1°C drop in core temperature was 16 (IQR 15, 32) min. Temperature changed over time with median lowest temperature being 33.1°C (IQR 32.8°C, 34.1°C). Neither heart rate nor diastolic blood pressures changed over time. Systolic blood pressure decreased over time. Subjects responded to verbal stimuli and completed tasks throughout the protocol. During cooling and maintenance, subjects reported discomfort and the sensation of being cold.CONCLUSION: Dexmedetomidine facilitates shivering suppression during prolonged cooling in healthy individuals. Subjects are easily roused, have mild decreases in systolic blood pressure, and note sensations of discomfort and cold. Cooling to suppress metabolism is a feasible countermeasure to prolong astronaut endurance.Rittenberger JC, Flickinger KL, Weissman A, Repine M, Elmer J, Guyette FX, Callaway CW. Cooling to facilitate metabolic suppression in healthy individuals. Aerosp Med Hum Perform. 2019; 90(5):475-479.

Spaceflight-related ocular changes: the potential role of genetics, and the potential of B vitamins as a countermeasure

PURPOSE OF REVIEW

Within the last decade, it was realized that during and after long-duration spaceflight, some astronauts experience ophthalmic abnormalities including refractive changes, optic disc edema, globe flattening, choroidal folds, and cotton wool spots. Much research has been initiated and conducted, but little evidence is available to differentiate affected crewmembers.

RECENT FINDINGS

The first published data to distinguish between affected and nonaffected crewmembers identified biochemical differences in affected astronauts: one-carbon pathway metabolite concentrations were higher in these individuals than in nonaffected astronauts, even before flight. These data led to findings that genetics and B-vitamin status were predictors of the incidence of the ophthalmic abnormalities. A multihit hypothesis was developed, with genetics and B-vitamin status as two of several important elements that all contribute to endothelial dysfunction and ultimately to ophthalmic changes after flight. One of these contributing factors - response to carbon dioxide exposure - was recently documented to be affected by the same one-carbon pathway genetics.

SUMMARY

This line of research may help identify which astronauts are at risk of these ophthalmic changes, and allow targeted treatment. This research may have implications for clinical populations, including patients with polycystic ovary syndrome, that have similar biochemical, endocrine, and genetic characteristics, and it may shed light on why links between cardiovascular disease and the metabolites homocysteine and folate have been elusive and confounded.