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quote:Originally posted by NakedScientistThese breathable liquids for liquid ventilation do exist. They have been under development since the 1960s, and can also be used as a blood substitute (links below).Crucially they are are NOT water based and instead exploit fluorocarbon mixes which can absorb high concentrations of oxygen. Having said that, if you breathe oxygen at about 3 times normal pressure you can dissolve enough in normal plasma to supply the needs of the body without having to have any haemoglobin ! (My memory might be slightly rusty on this one, so don't try it at home !).But, to address quantum's point, the surfaces of alveoli (the lung air-sacs) are coated with a sufactant comprising 80% phospholipids, 10% proteins, and 10% neutral lipids. The predominate phospholipids are phosphatidylcholine (PC) and phosphatidylglycerol. The purpose of lung surfactant is to abolish hydrophilic attraction (hydrogen bonding) on the alveolar surface. This greatly increases the collapsing pressure - in other words the alveoli can remain patent at a much lower pressure, and much less effort is required to inflate them. One of the problems faced by premature babies is poor lung function because they don't produce any surfactant which is why they struggle to breathe. The liquid ventilation technology is one approach being developed to tackle this problem because it incorporates a surfactant and doesn't hydrogen bond like water.Liquid Ventilation Link : http://www.sybd.com/LV.htmlBlood substitute : http://www.allp.com/Oxygent/ox_fact.htm
quote:Originally posted by chrisI rather suspect that the patting on the back contributes little to expelling water from the lungs. Being squeezed through a hole that usually measures a few cm across almost certainly takes care of that !For this reason I do wonder about the future with all these caesarian sections that are going on amongst the "too posh to push" brigade.Few women realise the consequences of a caesarian which they view as 'routine'. It is major abdominal surgery with risks of infection, haemorrhage, uterine rupture in future pregnancies, a long recovery time (not allowed to drive for 6 weeks afterwards) and long term consequences including the prospect of adhesions and potentially condemning yourself to another caesarian for any future children because the uterus is weakened. For many of these people the motivation is purely selfish - convenient childbirth at an appointed time so they don't have to miss that crucial meeting at the office !Here we are living in a world obsessed with sterility to the extent that it may be driving us to develop allergies at record rates (prevalence of asthma up tenfold to less than 1 person in 10 compared with 1 person in 20 ten years ago) and people are still looking for ways to mess themselves up ! Madness.Chris