title: Impedance cardiography as a tool for haemodynamic monitoring at high altitude: a preliminary study.
abstract: BACKGROUND
  Altitude illness is a relevant threat to the life and health of participants in mountaineering expeditions.
  
  
  OBJECTIVE
  To determine if impedance cardiography (ICG) can be used in noninvasive monitoring of haemodynamic disturbances at high altitude.
  
  
  METHODS
  The study was performed in a group of 13 participants of two mountaineering expeditions in the Himalayas. The ICG examination was performed before the expedition and again at high altitude (4,300-5,700 m) with concurrent estimates of clinical symptoms of acute mountain sickness (AMS) and those suggesting an increased risk of high altitude pulmonary oedema (HAPO).
  
  
  RESULTS
  High altitude influenced the haemodynamic profile of the subjects. Significant changes were observed for: stroke index (baseline vs. high altitude: 51.2 ± 10.3 vs. 35.5 ± 11.3 mL/m(2); p = 0.0007), cardiac index (3.24 ± 0.49 vs. 2.63 ± 0.66 L/min/m(2); p = 0.013), Heather index (16.6 ± 4.3 vs. 12.8 ± 4.45 Ohm/s(2); p = 0.006), heart rate (64.1 ± 11.7 vs. 75.4 ± 15.4 1/min; p = 0.045) and systemic vascular resistance index (2,051.3 ± 438.9 vs. 2,668.4 ± 856.2 dyn × s × cm(-5) × m(2); p = 0.027). AMS was observed in six subjects (mild: n = 5, severe: n = 1). Three of them revealed symptoms suggesting an increased risk of HAPO and this subgroup (vs. subgroup without such symptoms) was characterised by higher thoracic fluid content index (baseline: 19.2 ± 0.9 vs. 17.9 ± 2.0 1/kOhm x m(2); p = 0.176, at high altitude: 20.8 ± 1.4 vs. 17.7 ± 1.6 1/kOhm x m(2); p = 0.018) and lower Heather index (baseline: 11.4 ± 2.0 vs. 18.2 ± 3.5 Ohm/s(2); p = 0.028, at high altitude: 9.2 ± 2.1 vs. 13.9 ± 4.4 Ohm/s2; p = 0.028).
  
  
  CONCLUSIONS
  ICG may be a helpful, noninvasive tool in monitoring cardiovascular dysfunction occurring at high altitude, especially with breathing disorders.
authors.affiliation: Department of Cardiology and Internal Diseases, Military Institute of Medicine, Warsaw, Poland. pkrzesinski@wim.mil.pl
authors.forename: Paweł
authors.initials: P
authors.lastname: Krzesiński
authors.forename: Narcyz Michał
authors.initials: NM
authors.lastname: Sadłoń
authors.forename: Kamil Tomasz
authors.initials: KT
authors.lastname: Grudzień
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Gielerak
authors.forename: Adam
authors.initials: A
authors.lastname: Stańczyk
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000175:diagnosis* / Q000503:physiopathology*; D002307:Cardiography, Impedance; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods*