Physiologic effects of surgical masking in children versus adults.

Background: Surgical masks remain a focal part of the CDC guidelines to decrease COVID-19 transmission. Evidence refuting significant effects of masking on ventilation is mostly limited to small studies, with a paucity of studies on children, and none comparing children to adults. Methods: A total of 119 subjects were enrolled (71 adults, 49 children) in a prospective interventional study with each subject serving as their own mask-free control. End tidal CO2 (ETCO2), inspired CO2 (ICO2), and respiratory rate were measured by nasal cannula attached to an anesthesia machine D-fend module. Pulse oximetry and heart rate were also followed. After the mask-free period, an ASTM Level 3 disposable surgical mask was donned and 15 min of mask-worn data were collected. Results: A steady state was confirmed for ETCO2 and ICO2 over the masked period, and mean ICO2 levels rose significantly (p < 0.001) after masking in all age groups. The increase in ICO2 for the 2- to 7-year-old group of 4.11 mmHg (3.23-4.99), was significantly higher (p < 0.001) than the final ΔICO2 levels for both the 7- to 14-year-old group, 2.45 mmHg (1.79-3.12), and adults, 1.47 mmHg (1.18-1.76). For the pediatric group there was a negative, significant correlation between age and ΔICO2, r = -0.49, p < 0.001. Masking resulted in a statistically significant (p < 0.01) rise in ETCO2 levels of 1.30 mmHg in adults and 1.36 mmHg in children. The final respective ETCO2 levels, 34.35 (33.55-35.15) and 35.07 (34.13-36.01), remained within normal limits. Pulse oximetry, heart rate, and respiratory rate were not significantly affected. Discussion: The physiology of mechanical dead space is discussed, including the inverse relationship of subject age vs ICO2. The methodology and results are compared to previously published studies which detracted from the physiologic safety of surgical masking. Conclusions: The wearing of a surgical mask results in a statistically significant rise in ICO2 and a smaller rise in ETCO2. Because ETCO2 and other variables remain well within normal limits, these changes are clinically insignificant.

The effect of hypochlorous acid on the filtration performance and bacterial decontamination of N95 filtering facemask respirators.

BACKGROUND: Stabilized hypochlorous acid (HOCl) is increasingly used as a hospital disinfectant and antiseptic, yet its effect on N95 filtration facemask respirators (FFR) is unknown. These FFRs could also contribute to fomite-based transmission of nosocomial infections if worn for extended use between patient rooms. METHODS: Filtration performance of N95 FFR fabric swatches was assessed after various levels of HOCl exposure. N95 swatches were then contaminated with 108Escherichia coli or 108Staphylococci aureus and treated with HOCl solution, 70% ethyl alcohol, or normal saline. Surviving bacterial numbers were assessed by plate counts. RESULTS: The size-dependent filtration efficiency of HOCl-sprayed N95 FFR fabric ranged from 96% to 100%, showing no significant change. Flow resistance testing revealed almost no change compared to control. Submersion in HOCl, but not spraying, had an excellent bactericidal effect on contaminated swatches. DISCUSSION: The role of the outer hydrophobic layer of N95 FFRs is discussed regarding the effects of HOCl on filtration and bacterial decontamination. CONCLUSIONS: N95 material, sprayed with or briefly submerged in HOCl, maintained its filtration function. HOCl delivery by spray pump, however, would not accomplish decontamination of extended use FFRs between patient encounters. HOCl submersion of intact FFRs, contaminated with various hospital pathogens, is worth further study.

Smartphone Thermal Imaging in the Detection of Testicular Ischemia.

OBJECTIVE: To evaluate smartphone thermal imaging as a point of care test in the detection of testicular ischemia. Thermal imaging detects the infrared (heat) pattern of an object and the technology is now available as an inexpensive attachment to smartphones. MATERIALS AND METHODS: Smartphone thermal imaging was studied as a point-of-care diagnostic test for testicular ischemia in an IACUC approved study that prioritized survival of all animal subjects. Thirty canines weighing over 12 kg were observed during elective neuter procedures with consent from owners. Randomization determined ligation of the right vs left spermatic cord. With both testicles remaining in the scrotum, blinded inspection was performed with a FLIR ONE Pro thermal imaging camera for smartphone use. The bilateral orchiectomy procedures were then completed as planned. RESULTS: Within 11 minutes of ligation of the randomized spermatic cord, an obvious change in the thermal imaging pattern allowed for the correct diagnosis of the ischemic testicle in 30/30 (100%) of subjects in a blinded fashion. Temperature differences between testicles at the time of ischemia diagnosis ranged from 0.7°C to 3.7°C with an average difference of 1.79°C lower in the ischemic testicle (95% CI: [1.50, 2.08]). A thermal imaging evaluation of the testicles takes 30 seconds to perform. CONCLUSION: Smartphone thermal imaging correctly diagnosed testicular ischemia in 100% of animal subjects in a blinded fashion. The clinical utility of this emerging point-of-care technique in the evaluation of testicular torsion is currently unknown.