High Altitude Physiology Flashcards
Physiology of ventilation
Low pio2- dec pao2
Hyperventilation- resp alkalosis
Decreased resp drive - acclimated to hypoxia
Renal compens- inc bicarbonate secretion
Effect of hypoxia on pulm circulation
Hypoxic pulmonary vc- pulmonary htn
Effect of hypoxia on cerebral circulation
Increased metabolic rate- increased cerebral blood flow
O2 dissociation curve
Increased 2,3 dpg - right
Alkalosis- left
Overalk - right
Physiology of ams , hape , hace
Oxidative stress Endothelial damage by hypoxia Permeability Cheyne stokes Disrupted sleep arousals Dysregulation of macro and micro circulstory flow
Ams symptoms and rx
Scoring system
Headache + n/v/ insomnia/dizziness
Lakelouis scoring system
Rx-mild-acclimitisation Acetazolamide Symptomatic Promethazine Descent 02/hbt Dexa Temazepam- sleep disturbance
Prophylaxis ams
Acetazolamide
Prevention ams
Slow ascent <300/day after 3000 Should not spend more than one night Rest day every 2-3 days Acetazolamide 125 bd If c/i - dexa 4mg qid Pde5 inhibitors
Hape symptoms
Dry to wet cough- Frothy sputum
Dyspnoea
Chest Tightness
Pathophysiology hape
Htn- edema
Stress- leakage- edema.disturved alveolar fluid clearance
Mx of hape
Descent 500-1000 02 Nifedipine- 10mg s/l - rpt every 30 min Steroids No Pde5 Hbot
High Altitude cerebral edema diagnosis
Recent Altitude gain with or without ams+ ataxia/mental status change
Treatment
Immediate descent
Dexa/Acetazolamide
Hbot
Chronic mountain sickness/ monge
Path
Peripheral chemo receptor insensitive to hypoxia
Hpvc
Cor pulmonale
Inc hb
Rx of cms
Definitive rx- descent
Phlebotomy
Medroxyprogesterone
