Hypoxia-altitude Testing to Predict Altitude Related Adverse Health Effects in Chronic Obstructive Pulmonary Disease (COPD) Patients
Condition: Hypoxia Altitude Simulation Test; High Altitude
MeSH terms: Hypoxia
Study type: Observational

Summary: 
      The predictive value of the hypoxia altitude simulation test (HAST) or other baseline values
      to predict altitude-related adverse health effects (ARAHE) is not established. To address
      this gap, the main goals of this investigation will be 1) to evaluate the diagnostic accuracy
      of the HAST in identifying individuals that will experience ARAHE during altitude travel and
      2) to establish prediction models incorporating other commonly assessed clinical
      characteristics either alone or in combination with the HAST as predictors of ARAHE in
      altitude travelers.

      Hypotheses: In lowlanders with COPD, a PaO2 <6.6 kPa or another cutoff of PaO2 or SpO2 at the
      end of the HAST, at rest or during exertion and/or clinical variables including symptoms,
      pulmonary function indices, 6-min walk distance (6MWD), either alone or combined to a
      multivariable model, will predict ARAHE during a sojourn of 2 days at 3100m with accuracy
      greater than chance
    

Detailed description: 
      Altitude or air travel has become increasingly popular for recreational and professional
      reasons. Chronic obstructive pulmonary disease (COPD) affects up to 12% of adults worldwide
      and is associated with progressive hypoxemia, especially during exercise, due to respiratory
      mechanical constraints, airway obstruction and increasing pulmonary hypertension (PH). COPD
      patients are at increased risk of ARAHE including acute mountain sickness (AMS) and severe
      hypoxemia. Factors assessed at lowland that would predict ARAHE of COPD patients exposed to a
      hypobaric hypoxic environment at altitude or during air travel would be highly warranted.
      During the HAST COPD-patients are exposed to an inspiratory oxygen fraction (FiO2) of 15.1%
      corresponding to an altitude of ≈ 2500m and this test was designed to predict deoxygenation
      at altitude. The predictive value of the HAST or other baseline values to predict ARAHE is
      not established. To address this gap, the main goals of this investigation will be 1) to
      evaluate the diagnostic accuracy of the HAST in identifying individuals that will experience
      ARAHE during altitude travel and 2) to establish prediction models incorporating other
      commonly assessed clinical characteristics either alone or in combination with the HAST as
      predictors of ARAHE in altitude travelers.

      For this diagnostic accuracy study, COPD-patients with an FEV1 40-80% predicted living < 1000
      m without severe hypoxemia (SpO2, <92%), hypercapnia (PaCO2 >6 kPa) or comorbidities will be
      recruited to traveling to and staying for two nights at 3100 m. At 760 m, the HAST will be
      performed, at 760 m and 3100 m symptoms, vital signs, SpO2, pulmonary function tests, 6MWD,
      sleep studies will be repetitively assessed. ARAHE will be defined if one of the following
      present: AMS with a Lake Louise questionnaire score >4 including headache, or AMSc score
      ≥0.7, resting SpO2 <80% >30 min or <75% for >15 min; or exercise SpO2 <75% for >5 min
      accompanied by symptoms, any intercurrent illness including infections, hypertension,
      neurologic impairments, dyspnea or discomfort at rest requiring oxygen treatment, chest pain
      and/or ECG signs of cardiac ischemia.
    

Intervention name(s): hypoxia altitude simulation test (HAST) at 760m; High Altitude (3100m)
Intervention type(s): Other; Procedure
Intervention description(s): Normobaric hypoxia at a FiO2 of 15.1% will be generated by the Everest Summit II altitude generator (Hypoxico Altitude Training Systems, Bickenbach, Germany) and delivered to the patients face via tubes and a tightly fitted mask. Patients will be seated comfortably in a chair and fitted with a full-face mask equipped with a one-way valve. After a baseline period of quiet rest of 5-10 min with ambient air breathing and installation of equipment, patients will breath the hypoxic air mixture via a tightly fitted facial mask. They will be monitored with a finger-tip pulseoximetry to continuously assess SpO2 and heart rate. After at least 15' and steady-state values of the SpO2 (±1%) for at least 5' arterial blood gases will be drawn from a radial artery and immediately analyzed (RapidPoint 500, Siemens, Zürich, Switzerland).; High Altitude (3100m) exposure for 2 days
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        COPD-patients living in the Bishkek area (mean altitude 760m) will be recruited among
        patients of the outpatient clinic of the National Center for Cardiology and Internal
        Medicine.
      
Keywords: Hypoxia altitude simulation test (HAST); Chronic obstructive pulmonary disease; Mountain Sickness; Altitude-related adverse health effects (ARAHE)