ENVIRONMENTAL
ALTITUDE
PromptDefinitions - Acute mountain sickness, HACE, and HAPE
ResponseAcute mountain sickness (AMS) is the presence of headaches and at least one other symptom (nausea, vomiting, fatigue, weakness, dizziness, lightheadedness or difficulty sleeping) in the setting of a recent gain in altitude.
High altitude cerebral oedema (HACE) is considered a form of “severe AMS” – it is characterised by the presence of a change in mental status and / or ataxia in the setting of a recent gain in altitude (either with or without preceding AMS symptoms).
High altitude pulmonary oedema (HAPE) is the presence of cough, dyspnoea at rest, reduced exercise tolerance and chest tightness along with physical signs of pulmonary oedema such as tachypnoea, cyanosis and crackles in the lung fields.
High altitude cerebral oedema (HACE) is considered a form of “severe AMS” – it is characterised by the presence of a change in mental status and / or ataxia in the setting of a recent gain in altitude (either with or without preceding AMS symptoms).
High altitude pulmonary oedema (HAPE) is the presence of cough, dyspnoea at rest, reduced exercise tolerance and chest tightness along with physical signs of pulmonary oedema such as tachypnoea, cyanosis and crackles in the lung fields.
- ACI
PromptPathophysiology
ResponseAcute mountain sickness (AMS)/High altitude cerebral oedema
- Vasogenit cerebral oedema. Hypoxia causes cerebral vasodilation, leading to increased serebral blood volume and blood flow
- Leaky BBB - due to loss of autoregulation and increased permeability
- Not cardiogenic. Hydrostatic oedema
- Widespread but uneven pulmonary vasoconstriction. Heterogeneity of the response causes diversion of flow to less constricted areas with subsequent capillary leakage.
PromptHAPE
Response
PromptRisk factors for HAPE
ResponseRapid ascent
Genetics
Any pre existing pulmonary hypertension (previous PE, cardiac shunts ASD etc)
Exertion
Cold
Sleeping medications
Excess salt
Genetics
Any pre existing pulmonary hypertension (previous PE, cardiac shunts ASD etc)
Exertion
Cold
Sleeping medications
Excess salt
PromptTreatment of HAPE
ResponseImmediate descent - 500-1000 m or until symptoms resolve. Limit exertion
Oxygen to maintain saturations >90% - reduce hypoxic pulmonary vasoconstriction
Keep warm - reduce cold induced sympathetic effect
Minimise exertion
Nifedipine 60 mg daily in divided doses (P in HAPE, P in NifediPine - shitty memory aid!)
Portable hyperbaric compression chamber (But should not delay descent)
CPAP/EPAP mask (but like… on mt everest? - not really feasible)
Not enough evidence for Beta agonists, phosphodiesterase inhibitors, diuretics or corticosteroids
Oxygen to maintain saturations >90% - reduce hypoxic pulmonary vasoconstriction
Keep warm - reduce cold induced sympathetic effect
Minimise exertion
Nifedipine 60 mg daily in divided doses (P in HAPE, P in NifediPine - shitty memory aid!)
Portable hyperbaric compression chamber (But should not delay descent)
CPAP/EPAP mask (but like… on mt everest? - not really feasible)
Not enough evidence for Beta agonists, phosphodiesterase inhibitors, diuretics or corticosteroids
PromptHACE
Response
PromptPatient risk factors for AMS
ResponsePrior history of AMS
Younger age
Dehydration
Obesity
Pre-existing cardiopulmonary disease
Alcohol, stimulant or depressant drugs
Younger age
Dehydration
Obesity
Pre-existing cardiopulmonary disease
Alcohol, stimulant or depressant drugs
PromptAscent risk factors for AMS
ResponseFast/rapid ascent (>625 m/day at >2500m)
Ascent to higher altitude
Strenuous physical exertion
Sleeping at altitude
Ascent to higher altitude
Strenuous physical exertion
Sleeping at altitude
PromptMedical prevention of AMS
ResponseAcetazolamide 125mg BD (Up to 500 mg BD)
- Acetazolemide: - Decreased CSF formation + Decreased pH >> increased ventilation >> decreased symptoms - LITFL
PromptClinical features of acute mountain sickness
ResponseHeadache - worse with bending over/valsalva
Anorexia, nausea, +/- vomiting
Lassitude, weakness, irritability
Retinal haemorrhages
Fluid retention - peripheral/facial oedema
Anorexia, nausea, +/- vomiting
Lassitude, weakness, irritability
Retinal haemorrhages
Fluid retention - peripheral/facial oedema
PromptClinical features of High altitude cerebral oedema
ResponseHeadache
Confusion
Ataxia
Drowsiness
Stupor
coma
Confusion
Ataxia
Drowsiness
Stupor
coma
PromptTreatment for HACE
ResponseDescent
Supplemmental O2
Portible hyperbaric oxygen chamber
Acetazolamide 250 mg BD
Dexamethasone 8mg stat then 4mg QID
Supplemmental O2
Portible hyperbaric oxygen chamber
Acetazolamide 250 mg BD
Dexamethasone 8mg stat then 4mg QID
PromptNeed to do p 78-79!!
Response