2004 OPEN FORUM Abstracts
UN(EXPLAINED) HYPERVENTILATION
Prashant
N Chhajed, MD, FCCP 1, Wolf Langewitz, MD 2,
Michael Tamm, MD 1Divisions
of Respiratory Medicine1 and Psychosomatic
Medicine2, University Hospital Basel,
Switzerland
Introduction:
Psychosomatic hyperventilation is a clinical diagnosis.
Hyperventilation leads to a fall in the arterial carbon dioxide
tension. However, it is very difficult to document the continuous
fall in the arterial carbon dioxide tension during an episode of
hyperventilation.
Case
summary: A 30 year old man was referred from his General
Practitioner for resistant chronic pain, fatigue, muscular weakness,
and disturbed sleep. The patient wakes up at night with his whole
body being stiff and aching and burning sensations in the upper half
of the body and his face. Asked for any measure to alleviate the
symptoms he reported that sitting by the window and breathing calmly
would relieve his distress to some extent. An exacerbation in pain
intensity shows the following time course: air-hunger, stiffness in
the legs, then extending to the whole body, tingling and burning in
the feet, a feeling of pressure in the back and in his chest. Asked
explicitly for respiratory symptoms he admits dyspnea at rest and
occasionally on physical exercise. Lung auscultation was clear, chest
x-ray showed no infiltrates and lung function test revealed no
abnormalities. Maximum oxygen uptake on spiroergometry was 58%
predicted (22.8 ml/kg/min), maximum heart rate achieved was 85%
predicted (154/minute) and ventilatory reserve was 30% (46.7% maximum
voluntary ventilation). Arterial blood gas analysis on maximal
exercise showed ph 7.38, partial pressure of oxygen 96 mm Hg and
partial pressure of carbon dioxide 32.2 mm Hg. Day time capnography
was performed to check for hypocapnea as a marker of hyperventilation
using a new digital cutaneous carbon dioxide tension (PcCO2)
monitoring sensor (Sentec AG, Therwil, Switzerland) that was placed
on the left earlobe in the sitting position [1, 2]. The baseline
PcCO2 value was 33 mm Hg, which gradually increased to 35
mm Hg. An arterial blood gas was performed which revealed, ph 7.46,
partial pressure of carbon dioxide 36.2 mm Hg (parallel PcCO2
35.1 mm Hg), partial pressure of oxygen 92.2 mm Hg and bicarbonate
25.5 mmol/L. The patient was then offered a newspaper and was left
alone. When the doctor arrived in the room 10 minutes later, the
PcCO2 value was 26 mm Hg and the patient complained of
feeling faint. He was made to lay down and the blood pressure was
130/80 mm Hg in the left arm. Ten minutes later when he was feeling
well, he was again left alone in the room for ten minutes (PcCO2
was 29 mm Hg) and this was done twice. The lowest PcCO2
value was recorded as 21 mm Hg when the doctor entered the room for
the last time. At this time, another blood gas was done, which
revealed respiratory alkalosis showing ph 7.57, partial pressure of
carbon dioxide 25.2 mmHg (parallel PcCO2 24 mm Hg),
partial pressure of oxygen 83.7 mm Hg and bicarbonate 23.2 mmol/L.
The oxygen saturation during this entire test was above 96%.
Discussion:
The diagnosis in this patient was profound hyperventilation at rest.
A suspected diagnosis of hyperventilation in a patient with atypical
symptoms could be diagnosed by the use of cutaneous carbon dioxide
tension monitoring.