TY  - CHAP
M1  - Book, Section
TI  - High-Altitude Physiology and Clinical Disorders
A1  - Strohl, Kingman P.
A1  - Beall, Cynthia M.
A1  - Netzer, Nikolaus C.
A2  - Grippi, Michael A.
A2  - Antin-Ozerkis, Danielle E.
A2  - Dela Cruz, Charles S.
A2  - Kotloff, Robert M.
A2  - Kotton, Camille Nelson
A2  - Pack, Allan I.
PY  - 2023
T2  - Fishman’s Pulmonary Diseases and Disorders, 6e
AB  - Altitude  is  an  environmental  state  of  elevation  >760  m  (∼2500  ft)  above  sea  level  and  is  a  continuous  physiologic  stressor  of  hypobaric  hypoxia  (Fig.  91-1).  Altitudes  are  subdivided  into  very  high  (3500–5500  m  or  ∼11,500–18,000  ft)  and  extreme  (>5500  m  or  >18,000  ft).  Eighty  million  people  live  at  altitude  around  the  world,  and  40  million  people  per  year  travel  to  an  altitude  ≥2500  m  (∼8000  ft).1  Many  more  work  in  mines,  the  military,  or  border  operations  at  high  altitude.  Clinical  encounters  specific  to  altitude  result  from  hypoxemia  (FIO2  equivalent  to  ∼17%  O2  at  2500  m,  and  ∼8%  O2  at  the  summit  of  Everest),  which  leads  to  physiologic  responses  and  illnesses.  Such  illnesses  have  been  recognized  and  empirically  treated  in  prehistoric  native  populations.2  Birthweights  are  generally  lower,  and  the  rates  of  small-for-gestational-age  babies  and  congenital  heart  defects  are  higher  than  in  lowland  populations.3  With  a  hurried  ascent,  ∼80%  of  lowlanders  will  report  a  transient  headache  (high-altitude  headache  [HAH]),  and  some  will  develop  an  acute  high-altitude  illness:  acute  mountain  sickness  (AMS).  Fewer  will  develop  high-altitude  cerebral  edema  (HACE)  and  high-altitude  pulmonary  edema  (HAPE).3,4  HAH  and  AMS  are  annoying  and  interfere  with  activity  and  work;  however,  HACE  and  HAPE  can  be  fatal,  with  mortality  rates  approaching  30%.5–7  Some  residents  at  altitude  exhibit  chronic  mountain  sickness  (CMS)  and  right  ventricular  hypertrophy,  developing  over  months  to  years  of  residence  at  altitude.  Cold  air  and  extreme  exercise  also  may  contribute  to  illness.  Other  environmental  features  may  include  UV  radiation,  trauma,  and  infections  (which  are  not  covered  in  this  chapter).  Finally,  managing  illness  in  a  remote  altitude  location  can  be  challenging,  as  evacuation  to  a  lower  altitude  as  a  primary  treatment  may  be  limited  or  not  feasible.  
SN  - 
PB  - McGraw-Hill Education
CY  - New York, NY
Y2  - 2024/04/19
UR  - accessmedicine.mhmedical.com/content.aspx?aid=1195010597
ER  -