Publications

High ambient temperature and humidity greatly increase the risk of hyperthermia and mortality, particularly in infants, who are especially prone to dehydration. World areas at high risk of heat stress include many of the low-and middle-income countries (LMICs) where most of their inhabitants have no access to air conditioning. This study aimed to design, evaluate, and test a novel low-cost and easy-to-assemble device aimed at preventing the risk of infant hyperthermia in LMICs. The device is based on optimizing negative heat transfer from a small amount of ice and transferring it directly to the infant by airflow of refrigerated air. As a proof of concept, a device was assembled mainly using recycled materials, and its performance was assessed under laboratory-controlled conditions in a climatic chamber mimicking realistic stress conditions of high temperature and humidity. The device, which can be assembled by any layperson using easily available materials, provided sufficient refrigerating capacity for several hours from just 1–2 kg of ice obtained from a domestic freezer. Thus, application of this novel device may serve to attenuate the adverse effects of heat stress in infants, particularly in the context of the evolving climatic change trends. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: air conditioning, ambient-temperature, death, heat, heat index, heat shock, heatwave, high ambient temperature, hyperthermia, low-cost refrigeration, low-middle income countries, mortality, negative heat transfer, Air conditioning, Algorithm, Article, Climate change, Cost benefit analysis, Environmental temperature, Heat index, Heat shock, Heat stress, Heat transfer, Heating, Heatwave, High ambient temperature, High temperature, Humidity, Hyperthermia, Low income country, Low-cost refrigeration, Low-middle income countries, Middle income country, Middle-income countries, Negative heat transfer, Prevention study, Refrigeration, Temperature stress, Thawing

Lung bioengineering based on decellularized organ scaffolds is a potential alternative for transplantation. Freezing/thawing, a usual procedure in organ decellularization and storage could modify the mechanical properties of the lung scaffold and reduce the performance of the bioengineered lung when subjected to the physiological inflation-deflation breathing cycles. The aim of this study was to determine the effects of repeated freezing/thawing on the mechanical properties of decellularized lungs in the physiological pressure-volume regime associated with normal ventilation. Fifteen mice lungs (C57BL/6) were decellularized using a conventional protocol not involving organ freezing and based on sodium dodecyl sulfate detergent. Subsequently, the mechanical properties of the acellular lungs were measured before and after subjecting them to three consecutive cycles of freezing/thawing. The resistance (RL) and elastance (EL) of the decellularized lungs were computed by linear regression fitting of the recorded signals (tracheal pressure, flow, and volume) during mechanical ventilation. RL was not significantly modified by freezing-thawing: from 0.88 ± 0.37 to 0.90 ± 0.38 cmH2O·s·mL-1 (mean ± SE). EL slightly increased from 64.4 ± 11.1 to 73.0 ± 16.3 cmH2O·mL-1 after the three freeze-thaw cycles (p = 0.0013). In conclusion, the freezing/thawing process that is commonly used for both organ decellularization and storage induces only minor changes in the ventilation mechanical properties of the organ scaffold.

JTD Keywords: Elastance, Freezing/thawing, Lung bioengineering, Lung decellularization, Mechanical ventilation, Organ scaffold