The Control of Metabolic CO2 in Public Transport as a Strategy to Reduce the Transmission of Respiratory Infectious Diseases.

The global acceptance of the SARS-CoV-2 airborne transmission led to prevention measures based on quality control and air renewal. Among them, carbon dioxide (CO2) measurement has positioned itself as a cost-efficiency, reliable, and straightforward method to assess indoor air renewal indirectly. Through the control of CO2, it is possible to implement and validate the effectiveness of prevention measures to reduce the risk of contagion of respiratory diseases by aerosols. Thanks to the method scalability, CO2 measurement has become the gold standard for diagnosing air quality in shared spaces. Even though collective transport is considered one of the environments with the highest rate of COVID-19 propagation, little research has been done where the air inside vehicles is analyzed. This work explores the generation and accumulation of metabolic CO2 in a tramway (Zaragoza, Spain) operation. Importantly, we propose to use the indicator ppm/person as a basis for comparing environments under different conditions. Our study concludes with an experimental evaluation of the benefit of modifying some parameters of the Heating-Ventilation-Air conditioning (HVAC) system. The study of the particle retention efficiency of the implemented filters shows a poor air cleaning performance that, at present, can be counteracted by opening windows. Seeking a post-pandemic scenario, it will be crucial to seek strategies to improve air quality in public transport to prevent the transmission of infectious diseases.

SARS-CoV-2 Droplet and Airborne Transmission Heterogeneity.

The spread dynamics of the SARS-CoV-2 virus have not yet been fully understood after two years of the pandemic. The virus's global spread represented a unique scenario for advancing infectious disease research. Consequently, mechanistic epidemiological theories were quickly dismissed, and more attention was paid to other approaches that considered heterogeneity in the spread. One of the most critical advances in aerial pathogens transmission was the global acceptance of the airborne model, where the airway is presented as the epicenter of the spread of the disease. Although the aerodynamics and persistence of the SARS-CoV-2 virus in the air have been extensively studied, the actual probability of contagion is still unknown. In this work, the individual heterogeneity in the transmission of 22 patients infected with COVID-19 was analyzed by close contact (cough samples) and air (environmental samples). Viral RNA was detected in 2/19 cough samples from patient subgroups, with a mean Ct (Cycle Threshold in Quantitative Polymerase Chain Reaction analysis) of 25.7 ± 7.0. Nevertheless, viral RNA was only detected in air samples from 1/8 patients, with an average Ct of 25.0 ± 4.0. Viral load in cough samples ranged from 7.3 × 105 to 8.7 × 108 copies/mL among patients, while concentrations between 1.1-4.8 copies/m3 were found in air, consistent with other reports in the literature. In patients undergoing follow-up, no viral load was found (neither in coughs nor in the air) after the third day of symptoms, which could help define quarantine periods in infected individuals. In addition, it was found that the patient's Ct should not be considered an indicator of infectiousness, since it could not be correlated with the viral load disseminated. The results of this work are in line with proposed hypotheses of superspreaders, which can attribute part of the heterogeneity of the spread to the oversized emission of a small percentage of infected people.

Neuroapoptosis in newborns with respiratory acidosis at birth.

BACKGROUND: S100B protein is one of the most accurate biomarkers for diagnosis of neuroapoptosis and brain damage. The aim was to evaluate the lactate concentration and acid-base balance (pH, pCO2, pO2, HCO3c and BEb) in umbilical cord blood to predict high risk of neuroapoptosis and analyze the relationship between the levels of these biomarkers and umbilical cord blood S100B protein concentration at birth. METHODS: Apparently healthy newborns were included. S100B protein and blood gas test (lactate and acid-base balance) were determined in umbilical cord blood at birth. Newborns were classified into two groups: with and without high risk of neuroapoptosis. Newborns with high umbilical cord blood S100B protein concentration were considered newborns at high risk of neuroapoptosis. RESULTS: Sixty-one newborns were included, 12 had high risk of neuroapoptosis and 49 did not. S100B protein concentration correlate directly with pCO2 levels (Rho: 0.286, p = .0321) and lactate concentration (Rho: 0.278, p = .0315); and indirectly with pH (Rho: -0.332, p = .01). The analysis of the ROC curves yielded significant curves for pH and pCO2 to predict high risk of neuroapoptosis, pH optimal cutoff value was 7.19 (sensitivity: 50%, specificity: 83.7%, AUC: 0.708); and pCO2 optimal cutoff value was 60 mmHg (sensitivity: 30%, specificity: 85.4%, AUC: 0.705). CONCLUSIONS: Respiratory acidosis is associated to high concentrations of S100B protein in umbilical cord blood at birth. Umbilical cord blood pH and pCO2 may be useful in differentiating newborns at high risk of neuroapoptosis. Umbilical cord blood gas test may be valuable as risk indicator for neuroapoptosis at birth.

Treatment of D alloimmunization in pregnancy with plasmapheresis and intravenous immune globulin: case report.

The prevalence of D alloimmunization occurs between 0.15% and 0.4%. The anti-D can cross the placenta and cause hemolysis and fetal anemia. At present, a Doppler study of the middle cerebral artery allows the monitoring of the degree of fetal anemia. The treatment in cases of moderate to severe anemia in fetuses of less than 34-35 weeks of gestation is intrauterine transfusion via cordocentesis. However, with high titers of anti-D, in the absence of fetal anemia it is possible to modulate the maternal immune response by plasmapheresis and intravenous immunoglobulin administration. We present a case report of an Rh(D) alloimmunized pregnancy treated with plasmapheresis followed by intravenous immunoglobulin administration. We performed a caesarean section at 31 weeks, 5 days of gestation. The hemoglobin at birth was 13.8 g/dl and hematocrit 40.8%. Intrauterine transfusion was not necessary.

Assessment of a head support system to prevent pediatric out-of-position: an observational study.

Head injuries are the most common severe injuries sustained by pediatric occupants in road traffic crashes. Preventing children from adopting positions that can result in an increased injury risk due to unfavorable interactions with the restraints is fundamental. The objective of this paper was to assess the effect of a head support system (SS) on the lateral position of the head, the vertical position of the sternum and the shoulder belt fit. Thirty pediatric rear-seat passengers were exposed to two 75-minute trials. Volunteers were restrained by a three-point belt and, if needed, used the appropriate child restraint system for their anthropometry (high-back booster, low-back booster, no booster). A case crossover study was designed in which the volunteers used the head support system (SS) during one of the trials, acting as their own controls (No SS) in the other. Compared to the control group, the head support reduced significantly the 90(th) percentile value of the absolute value of the relative lateral motion of the head, regardless of the restraint used. The system also reduced the maximum downward position of the sternal notch within the low-back booster group. As for the belt fit, the use of the head support improved significantly the position of the shoulder belt on the occupant in the low-back booster and in the no booster groups.