Respiratory insensitivity to hypoxia in chronically hypoxic man

摘要: Abstract Respiratory chemosensitivity was studied in Cerro de Pasco, Peru (4330 m) 5 normal highlanders (H), 6 with chronic mountain polycythemia (CMP) without right heart failure, and 7 lowlanders (L) acclimatized for 1–40 weeks. Mean age of groups 35 pulmonary function normal. Hematocrit averaged 51.7 L, 60.1 H 75.4 CMP. P aco 2 27.8 ±0.6 mm Hg (s.e.) 31.9±0.7 34.8±0.9 Similarity CO2 response curve slopes 2.6 1/min/m2/mm 2.5 2.2 CMP suggested that medullary chemoreceptor sensitivity although set chemically, by CSF HCO3− adjustment, to operate at differing co levels the 3 groups. However, ventilatory hypoxia ( Pa =40 ) control differed, being 211/min/m3 5.6 only 2.4 CMP, PaO2 as low 22 failed induce hyperpnea either or It is postulated results desensitization carotid body chemoreceptors, reduced stimulus permits ventilation fall rise. This process may be etiologic sickness.