The physiological and disturbing effects of surgical face masks in the COVID-19 era

BACKGROUND

In the COVID-19 pandemic, the concern about mask-harmful effects disturbed mask-adherence. However, it is not certain whether the masks cause cardiopulmonary overload.

OBJECTIVE

To investigate the physiological and disturbing effects of surgical face masks during exercise.

METHOD

The study was conducted in a tertiary hospital with 100 healthy volunteers between September 2020 and January 2021. Individuals with impaired walking, cardiopulmonary disease, and smoking were not included in the study. Initially, respiratory rate (RR), heart rate (HR), oxygen saturation (SpO2), end-tidal carbon dioxide (EtCO2) were measured.  Participants underwent 6-minute walking test (6MWT) with and without surgical masks.  Mask-discomfort questionnaire was applied before and after 6 MWT with the mask.

RESULTS

Surgical masks during 6 MWTs significantly increased HR, RR, and EtCO2 levels (p<0.001).  Walking distance (p<0.001) and SpO2 level (p=0.002) were significantly decreased with mask. In Mask-Discomfort Questionnaire, humidity, temperature, resistance, salinity, odor, fatigue (p<0.001), and itching (p=0.001) scores significantly increased after 6MWT with mask.

CONCLUSION

In healthy volunteers, HR, RR, EtCO2 were increased, and SpO2 and walking distance were decreased in the short-term, light exercise performed with the surgical mask. Findings support the concern that masks may cause cardiopulmonary overload (Tab. 3, Fig. 1, Ref. 17). Text in PDF www.elis.sk Keywords: COVID-19, masks, physiology, psychological side effects, questionnaire.

Evening preference correlates with regional brain volumes in the anterior occipital lobe

Chronotype or diurnal preference is a questionnaire-based measure influenced both by circadian period and by the sleep homeostat. In order to further characterize the biological determinants of these measures, we used a hypothesis-free approach to investigate the association between the score of the morningness-eveningness questionnaire (MEQ) and the Munich chronotype questionnaire (MCTQ), as continuous variables, and volumetric measures of brain regions acquired by magnetic resonance imaging (MRI). Data were collected from the Baependi Heart Study cohort, based in a rural town in South-Eastern Brazil. MEQ and anatomical 1.5-T MRI scan data were available from 410 individuals, and MCTQ scores were available from a subset of 198 of them. The average MEQ (62.2 ± 10.6) and MCTQ (average MSFsc 201 ± 85 min) scores were suggestive of a previously reported strong general tendency toward morningness in this community. Setting the significance threshold at P > .002 to account for multiple comparisons, we observed a significant association between lower MEQ score (eveningness) and greater volume of the left anterior occipital sulcus (β = -0.163, p = .001) of the occipital lobe. No significant associations were observed for MCTQ. This may reflect the smaller dataset for MCTQ, and/or the fact that MEQ, which asks questions about preferred timings, is more trait-like than the MCTQ, which asks questions about actual timings. The association between MEQ and a brain region dedicated to visual information processing is suggestive of the increasingly recognized fluidity in the interaction between visual and nonvisual photoreception and the circadian system, and the possibility that chronotype includes an element of masking.

Role of endothelin receptors and relationship with nitric oxide synthase in impaired erectile response in diabetic rats

To evaluate the protective role of bosentan (BOS), an endothelin-1 (ET-1) receptor antagonist, and to show the changes in rats with experimentally induced diabetic erectile dysfunction (ED), a total of 24 albino Wistar rats were allocated into four groups. Group 1 was the healthy group and Group 2 had diabetes mellitus (DM) induced by intraperitoneal injection of 60 mg kg^-1 streptozotocin (STZ). Following the establishment of DM, Group 3 and Group 4 were treated with oral BOS doses of 50 mg kg^-1 and 100 mg kg^-1 , respectively, for 60 days. At the end of the treatment, we evaluated yawning and erection response to apomorphine treatment and then the animals were sacrificed. ET-1, eNOS, iNOS, tumour necrosis factor (TNF)-α, ET-RA and ET-RB mRNA expressions were analysed in cavernosal tissue. It was observed that yawning and erection response decreased in the diabetic group; however, both of these improved with BOS treatment. While ET-1, TNF-α and iNOS gene expressions increased, eNOS, ET-RA and ET-RB gene expressions decreased in the DM group compared to the healthy group. DM has a negative impact on cavernosal tissue blood flow through activating vasoconstrictor mediators in cavernosal tissue. BOS regulates significantly eNOS, iNOS and TNF-α expressions in a dose-dependent manner.

Differences in nephrotoxicity risk and renal effects among anti-viral therapies against hepatitis B

BACKGROUND

Results are conflicting with respect to the renal effects of anti-viral agents used for hepatitis B virus infection.

AIM

To compare short and long-term renal effects in real-life settings and to determine risk factors for renal impairment during treatment.

METHODS

2221 treatment-naïve patients were enrolled. Among these, 895 (302 lamivudine, 27 telbivudine, 282 entecavir, 273 tenofovir and 11 adefovir initiated patients) had 'repeated measures' of creatinine (baseline, 1st, 6th, 12th and 24th month of treatment). Telbivudine and adefovir groups were excluded from further analysis because of the low number of patients. We calculated the glomerular filtration rate (GFR) using the Modification of Diet in Renal Disease (MDRD) formula at each time point. Hypophosphataemia was also recorded. Risk factors for renal impairment were analysed.

RESULTS

Tenofovir caused a decline in GFR at each time point when compared to baseline levels. However, lamivudine and entecavir did not change GFR. GFR-shifting from ≥90 to 60-89 mL/min/1.73 m(2) was comparable among groups. The proportion of patients whose baseline creatinine increased more than 25% was comparable among all anti-virals. GFR showed a decline in patients who switched from entecavir to tenofovir. One patient with compensated cirrhosis needed to change from tenofovir because of renal safety. Seven and three patients developed transient hypophosphataemia in the tenofovir and lamivudine groups, respectively.

CONCLUSIONS

Although tenofovir caused a decline in GFR, differences between the anti-viral agents do not appear to be so impressive. In patients with and without renal risk factors at baseline, there is no impact of anti-virals, including tenofovir.

Reproducibility of technetium-99m ethylenedicysteine clearance

It has been shown that technetium-99m ethylenedicysteine ((99m)Tc-EC) clearance displays a strong correlation with orthoiodohippurate clearance and that it is possible to estimate effective renal plasma flow from (99m)Tc-EC clearance. However, in routine practice, when monitoring renal function of patients by clearance determinations it is imperative to test the reproducibility of the clearance technique in order to decide whether the changes in renal function are related to disease or not. The aim of this study was to test the reproducibility of (99m)Tc-EC clearance. The study group comprised 13 patients aged between 24 and 58 years (eight female and five male). Two patients had single kidneys due to agenesis and hypoplasia. Plasma creatinine and BUN levels were within the normal range and remained stable between two clearance studies. None of the patients were receiving medication. Two separate multiple sample clearance studies were performed in each patient within a week. The difference between two studies was expressed as a percentage of the mean value of the two studies, and the standard deviation of these percentages represented the precision. The plasma clearance of (99m)Tc-EC in the first-step studies ranged from 190 ml/min to 561 ml/min with a mean of 411+/-101 ml/min. The clearances obtained from the second-step studies ranged from 248 ml/min to 552 ml/min, with a mean of 387+/-94 ml/min. There was no statistically significant difference between the two clearance studies (P>0.05). There was a mean difference of 5.3% between the first and second clearance studies, and the precision was found to be 12.7%. In conclusion, this study suggested that consecutive (99m)Tc-EC clearance measurements should be interpreted cautiously.

Prospective validation of single plasma sample 99mTc-ethylenedicysteine clearance in adults

99mTc-L,L-ethylene, L, dicysteine (EC) clearance shows strong correlation with orthoiodohippurate clearance, and it is possible to estimate effective renal plasma flow from 99mTc-EC clearance. In routine clinical studies, it is practical to use the one or two plasma sample method instead of multiple plasma samples for clearance determination. A single-sample technique was developed for 99mTc-EC, and a regression formula was generated. A prospective study tested the validity of this regression formula.

METHODS

The study population was composed of 26 patients with a wide range of renal function. Multiple plasma sample 99mTc-EC clearances were calculated from all patients using the open two-compartment model. Single plasma sample clearances were also determined from the 54-min plasma sample using the regression formula published previously.

RESULTS

The multiple-sample plasma clearance of 99mTc-EC ranged from 46 to 668 mL/min with a mean of 300.76 +/- 150.73 mL/min. The clearances obtained from the 54-min plasma sample ranged from 49 to 699 mL/min, with a mean of 297.39 +/- 152.23 mL/min. There was an excellent correlation between the clearances obtained by the two techniques (r = 0.99, slope = 0.9911). The standard error of estimation was found to be 25.9 mL/min.

CONCLUSION

This study suggests that 99mTc-EC clearance can be estimated from 54-min plasma samples with an acceptable error of estimation for most routine clinical studies.

Simplified technetium-99m-EC clearance in adults from a single plasma sample

Technetium-99m-EC has recently been introduced as an alternative renal tubular agent to 131I-ortho iodohippurate (OIH). It has been shown that 99mTc-EC clearance shows strong correlation with OIH clearance and it is possible to estimate effective renal plasma flow. In routine clinical studies, it is practical to use one or two plasma sample methods instead of multiple plasma samples for clearance determination. An attempt was made to determine 99mTc-EC clearance with one sample method.

METHODS

Data from 72 subjects were collected. To increase the range of renal function, two anuric hemodialysis patients were also included. Clearances were determined by the open two-compartment model.

RESULTS

The clearance range was 12 ml/min to 660 ml/min with a mean of 275 +/- 117 ml/min. Analysis of correlation was made by Tauxe's method. The least standard error of estimation (s.e.e. = 32.71 ml/min) and the best correlation (r = 0.97) between the theoretical volume distribution and the clearance estimations were obtained from the 54-min plasma sample.

CONCLUSION

This study suggests that EC clearance could be determined by a simplified single-sample method with an acceptable s.e.e.