Geographical Epidemiology of the Toxemias of Pregnancy

A second important concept is the interaction between neural and chemical ventilatory drives. Tenney describes a suprapontine neural influence which appears to provide a neural basis for the blunted ventilatory responses to hypoxia characteristic of the adaption to chronic hypoxia. One recurrent and poorly understood problem concerns the interrelation between genetic, environmental, and adaptive responses to the chronic hypoxia of high altitude. There appear to be some variations in these responses depending on species, genetic, and ethnic factors. Further, the adaptation to hypoxia appears to depend on whether the subjects were born at altitude. There were lengthy discussions on how to relate respiratory anatomic size to body size since lung size:body weight ratios were increased in chronic hypoxia. This reviewer cannot help feeling that hypoxia is a stunting mechanism affecting general somatic growth. A final example of individual variation in these adaptive mechanisms is the proposal that chronic "mountain sickness" represents an example of primary central hypoventilation in a high-altitude resident. If this is correct, the disease then represents an example of the interaction of disease with environment. The Symposium makes interesting reading and the discussion is lively. There appear to be a number of areas that could be better covered, namely, the work of the Colorado group on respiratory control, and a fuller treatment of the carotid body mechanisms. The volume provides a convenient source of material in the area. If will not, however, become a major definitive treatment of the subject.