PART \I — HUMAN ADAPTATION TO ENVIRONMENTAL STRESS 



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Figure XI-6 — GROWTH RATE DIFFERENCES BETWEEN 

 NUNOA AND U.S. CHILDREN 



MALES 



Nuni-,.1 



FEMALES us 



..Nunoa 



The graph shows differences in rates of general body growth between Nunoa 

 and U.S. children. The Nunoa children are primarily of Indian derivation and live 

 in an area of about 1.600 square kilometers whose minimum altitude is 4.000 

 meters and whose maximum altitude is above 5,500 meters. The Nunoa children 

 have a slower rate of general body growth than is standard in the U.S., but their 

 growth rate continues over a longer period of time. 



earlier. However, their study de- 

 mands a large-scale multidisciplinary 

 approach in selected areas, in which 

 the various characteristics itemized 

 earlier would still have to be subjects. 



Health Aspects of Altitude 



Ischemic Heart Disease at High 

 Altitude — There is evidence that the 

 incidence of ischemic heart disease 

 in high-altitude populations is lower 

 than at sea level. Experimental stud- 

 ies indicated increased resistance to 

 myocardial necrosis in altitude-accli- 

 matized animals. A controlled epi- 

 demiological study of the incidence 

 of ischemic heart disease in high- 



altitude populations will be carried 

 out using suitable sea-level controls 

 and standardized techniques of in- 

 vestigation. Risk factors for ischemic 

 heart disease will be evaluated and 

 correlated with necropsy data. Adap- 

 tive mechanism of the heart to high 

 altitude pertinent to acute cardiac 

 necrosis will be examined in experi- 

 mental animals. Careful investigative 

 techniques of population analysis will 

 be employed and, depending on initial 

 results, preventive trials may be 

 initiated. 



Development of Prognostic Tests 

 for Altitude Sickness — It is impor- 

 tant to be able to identify individuals 

 who are likely to develop acute or 



chronic mountain sickness or high- 

 altitude pulmonary edema. Simple 

 laboratory methods for determining 

 the sensitivity of the carotid body 

 and respiratory responses to various 

 stimuli including hypoxia should be 

 devised. Other screening tests should 

 be evaluated on sea-level subjects 

 who will later be exposed to high 

 altitude. 



Epidemiology, Therapy, and Pre- 

 vention of High-Altitude Pulmonary 

 Edema — By means of questionnaires 

 and interviews, the importance of 

 factors such as reascent, length of 

 stay at sea level, and slow ascent 

 upon the occurrence of HAPE will 

 be assessed. Field trials of prophy- 

 lactic drugs, using a double-blind 

 technique, will be carried out, prefer- 

 ably in troops. In selected patients 

 during the acute stage the hemody- 

 namic effect of selected drugs will 

 be investigated. Ventilation-perfusion 

 characteristics will be examined se- 

 quentially in the acute stage and dur- 

 ing recovery. 



Congenital Malformations of the 

 Newborn at High Altitudes — Pre- 

 liminary studies have shown that 

 the incidence of congenital abnor- 

 malities of the heart and other struc- 

 tures is increased at high altitude. 

 Whether this is a genetic abnormality 

 or due to maternal hypoxia at a criti- 

 cal stage of fetal development is not 

 known. Since maternal hypoxia can 

 be prevented or minimized, studies 

 at high altitude are indicated. The 

 causative factors can be evaluated by 

 employing a standard, highly objec- 

 tive method of examination in a 

 prospective study of newborn infants 

 and schoolchildren at selected levels 

 of altitude in different countries. 

 Countries to be included are those 

 where the appropriate facilities are 

 available. The administration of ox- 

 ygen to newborns should be carried 

 out at high altitude with suitable 

 controls to determine its late effect 

 on the incidence of PDA and the 

 cardiovascular system. 



384 



