Ventilation animal laboratories

In a mixed occupancy building it is wise to consider the design of separate ventilation systems for laboratory areas, areas servicing the public, animal holding areas, and administrative offices. 

Facilities should be designed to avoid disturbances such as intermittent or continuous noise from within or outside the facdity, frequent traffic in and out of animal rooms, obnoxious odors (e.g., chemical odors that are carried by ventilation systems from laboratories to animal housing areas). 

Ribavirin is teratogenic and embryotoxic in laboratory animals and should not be given to pregnant women. Concern has been expressed about the safety of people in the same room as patients being treated with ribavirin by aerosol, particularly women of child-bearing age. However, no ribavirin was detected in the urine, plasma, or erythrocytes of 19 nurses exposed to ribavirin administered via ventilator, oxygen tent, or oxygen hood over 3 days (22). 

PBPK models are particularly useful for interspecies extrapolations of dose-response data. In using a PBPK model of uptake, distribution, and elimination, an exponential power (e.g., 0.75) of the body weight is used to scale the cardiac output and ventilation rate between the laboratory species (typically rat) and humans. A PBPK model will therefore contain adequate logic to account for routes of administration, storage tissues and residence time therein, elimination rates, and sufficient mathematical detail to mimic the integration of these processes. It is important that the model parameters (e.g., elimination rates) be validated as much as possible by separate kinetic studies in the relevant species. The ultimate test of the model is how the model predictions are for parameters such as blood levels, rate of metabolism, and tissue concentrations relative to real-life animal data for the chemical. 

Mice are also available from Tel Aviv University (TAU). Currently at TAU, aU CC mice are maintained in a conventional facihty, while the rederived hnes are maintained in individual ventilation cages (TVC) and housed in a SPF facility. CC hnes at TAU undergo routine microbiology monitoring according to the Federation of European Laboratory Animal Science Association (FELASA) recommendations (Nicklas et al., 2002). 

Malnutrition is highly prevalent among patients requiring PMV (37) and LTMV (70) and is assoeiated with poor prognosis (71). Malnutrition decreases muscle mass and respiratory muscle strength and enduranee (40). These effects on the respiratory muscles are partially reversible with nutritional support. The process, however, is slow, and in laboratory animals, it can take months of refeeding for muscle mass to return to normal values (72). To date, it remains unclear whether malnutrition by itself ean cause sufficient respiratory muscle weakness to produce ventilator dependence. It is more likely for malnutrition to be a contributing factor and not a sole cause of ventilator dependence. 

In laboratory animals, controlled mechanical ventilation delivered for 1 to 11 days can decrease diaphragmatic force generation by 20-50% and can cause similar decreases in diaphragmatic endurance (40). Several mechanisms, including stmctural injury, muscle atrophy, and oxidative stress, appear to be responsible for ventilator-associated respiratory muscle dysfunction (40). Of interest, in a study of more than 200 critically ill patients— 80% of whom required acute ventilator support—duration of mechanical ventilation was nearly three days shorter in those who completed a 10-day antioxidant supplementation protocol (vitamins E and C) than in those who completed a 10-day course of placebo (76). 

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