Lecture 8 "The Respiratory System Under Stress" Flashcards
how do you calculate inspired oxygen concentration?
PIO2=0.21x(Pb-47)
what are the three main challenges to the pulmonary system at atltitude?
hypoxia
low humidity
extreme cold
what happens to hypoxic drive at altitude?
hypoxic drive only lasts for 30 minutes, then respiratory rate drops and increases again over the next few days
what is the hematological effect of being at high altitude?
polycythemia, Everest showed an increase from 13.5 to 17
what happens to the oxy-Hb dissociation curve at altitude?
alkalosis shifts the curve to the left and increased 2,3 DPG shifts it to the right, overall the curve is shifted to the left to preserve O2 loading
what happens to minute ventilation, response to hypoxia, tidal volume and PCO2 in a high altitude resident?
increased minute ventilation
decreased ventilator response
increased TV
higher PCO2
is there a genetic component to high altitude adaptation?
yes
what is the primary and secondary compensation for low O2 delivery at altitude?
primary is CO
secondary is Hgb
what happens to VO2 max at altitude, and how does this affect PCO2 and PO2?
VO2 declines as a function of altitude, causing a decrease in PCO2 and an increase in PO2
what does HAPE stand for?
high altitude pulmonary edema
what is HAPE?
extreme pulmonary hypertension due to hypoxia, that is worsened by the increased CO of exercise
how do you treat HAPE?
nifedipine (CCB)
does not work as a preventative, only a treatment
what is high altitude cerebral edema?
all people at high altitudes have some degree of this
cerebral arterioles dilate in response to hypoxia, the hydrostatic P in the arteries increases and causes fluid to leave the vasculature resulting in cerebral edema
what does ataxia mean?
the inability to coordinate voluntary muscular movements
how do you treat acute mountain sickness?
symptoms resolve with time
acetazolamide (CA inhibitor)
what happens to patient’s with respiratory disease on flights?
changes from the flight may exacerbate chronic hypoxia
when is in-flight O2 needed for patients?
SaO2 < 92% on RA
PaO2 < 50 mmHg
what is the difference between drowning, near drowning and secondary drowning?
drowning is due to asphyxia by immersion
near drowning is survival of the drowning accident leading to secondary complications
secondary drowning is due to chemical and biological changes in the lungs after near drowning accidents