Changes in transthoracic electrical impedance at high altitude.

Mean transthoracic electrical impedance (impedance) which is inversely related to intrathoracic extravascular fluid volume was measured in 121 normal healthy volunteers at sea-level and at 3658 metres altitude. Fifty (group A) reached the high altitude location after an hour's journey in a pressurised aircraft. Twenty-five (group D) underwent slow road ascent including acclimatisation en route. Thirty permanent residents (group B) and 16 temporary residents at high altitude (group C) were also studied. Serial studies in the 30 subjects of group A who developed symptoms of high altidue sickness showed a significant decrease of impedance up to the fourth day of exposure to high altitude which later returned to normal. The 4 volunteers who developed severe symptoms showed the largest drop in impedance. A case of acute pulmonary oedema developing at 4300 metres showed an impedance value of 24-1 ohms on admission. After effective treatment the impedance increased by 11-9 to 36-0 ohms. Twenty asymptomatic subjects of group A and 25 of group D showed a small average increase in impedance values at high altitude. These obstructions suggest that measurement of transthoracic electrical impedance may be a valuable means of detecting incipient high altitude pulmonary oedema.

[1]  S K Guha,et al.  Transthoracic Electrical Impedance in Cases of High-altitude Hypoxia , 1974, British medical journal.

[2]  H. Fred,et al.  Acute Pulmonary Edema of Altitude , 1962 .

[3]  B Eiseman,et al.  Clinical Evaluation of Transthoracic Electrical Impedance as a Guide to Intrathoracic Fluid Volumes , 1970, Annals of surgery.

[4]  R. Luepker,et al.  Transthoracic electrical impedance; quantitative evaluation of a non-invasive measure of thoracic fluid volume. , 1973, American heart journal.

[5]  Menon Nd HIGH-ALTITUDE PULMONARY EDEMA: A CLINICAL STUDY. , 1965, The New England journal of medicine.

[6]  ACUTE MOUNTAIN SICKNESS , 1977, The Lancet.

[7]  H. Hultgren,et al.  Circulatory adaptation to high altitude. , 1968, Annual review of medicine.

[8]  Sujoy B. Roy,et al.  Immediate Circulatory Response to High Altitude Hypoxia in Man , 1968, Nature.

[9]  S. C. Manchanda,et al.  Effect of Frusemide on Pulmonary Blood Volume , 1969, British medical journal.

[10]  S. C. Manchanda,et al.  Effects of high altitude hypoxia on left ventricular systolic time intervals in man. , 1975, British heart journal.

[11]  P. Wood CIRCULATORY DYNAMICS , 1954 .

[12]  V. Balasubramanian,et al.  Changes in transthoracic electrical impedance during submaximal treadmill exercise in patients with ischemic heart disease--A preliminary report. , 1976, American heart journal.

[13]  B Eiseman,et al.  Transthoracic electrical impedance for the early detection of pulmonary edema. , 1969, Surgery.

[14]  J M Van de Water,et al.  Monitoring the chest with impedance. , 1973, Chest.

[15]  S. Roy,et al.  Pulmonary blood-volume in high-altitude pulmonary oedema. , 1968, Lancet.

[16]  H. Hufnagel,et al.  Transthoracic electrical impedance s a guide to intravascular overload. , 1971, Archives of surgery.

[17]  H. Fred,et al.  Acute Pulmonary Edema of Altitude: Clinical and Physiologic Observations , 1962 .

[18]  D. Peñaloza,et al.  Circulatory dynamics during high altitude pulmonary edema. , 1969, The American journal of cardiology.