Effort syndrome: hyperventilation and reduction of anaerobic threshold

Abstract:

Effort syndrome is an entity in danger of being subsumed into “chronic fatigue syndrome” and lost to sight. Its distinctive feature is the reduction of the anaerobic threshold for work by depletion of the body’s alkaline buffering systems through hyperventilation. This article describes the history and clinical features of effort syndrome and reports a study in which capnography is used to identify the anaerobic threshold by registering the respiratory response to the onset of metabolic acidosis. The patients’ thresholds are low, and provide a goal for rehabilitation. In other forms of chronic fatigue syndrome, the pathogenesis and logic of therapy are unclear.

 

Source: Nixon PG. Effort syndrome: hyperventilation and reduction of anaerobic threshold. Biofeedback Self Regul. 1994 Jun;19(2):155-69. http://www.ncbi.nlm.nih.gov/pubmed/7918753

 

Hyperventilation and chronic fatigue syndrome

Abstract:

We studied the link between chronic fatigue syndrome (CFS) and hyperventilation in 31 consecutive attenders at a chronic fatigue clinic (19 females, 12 males) who fulfilled criteria for CFS based on both Oxford and Joint CDC/NIH criteria. All experienced profound fatigue and fatigability associated with minimal exertion, in 66% developing after an infective episode. Alternative causes of fatigue were excluded.

Hyperventilation was studied during a 43-min protocol in which end-tidal PCO2 (PETCO2) was measured non-invasively by capnograph or mass spectrometer via a fine catheter taped in a nostril at rest, during and after exercise (10-50 W) and for 10 min during recovery from voluntary overbreathing to approximately 2.7 kPa (20 mmHg). PETCO2 < 4 kPa (30 mmHg) at rest, during or after exercise, or at 5 min after the end of voluntary overbreathing, suggested either hyperventilation or a tendency to hyperventilate. Most patients were able voluntarily to overbreathe, but not all were able to exercise.

Twenty-two patients (71%) had no evidence of hyperventilation during any aspect of the test. Only four patients had unequivocal hyperventilation, in one associated with asthma and in three with panic. Only one patient with severe functional disability and agoraphobia had hyperventilation with no other obvious cause. A further five patients had borderline hyperventilation, in which PETCO2 was < 4 kPa (30 mmHg) for no more than 2 min, when we would have expected it to be normal. There was no association between level of functional impairment and degree of hyperventilation. There is only a weak association between hyperventilation and chronic fatigue syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Comment in: Hyperventilation and the chronic fatigue syndrome. [Q J Med. 1994]

Source: Saisch SG, Deale A, Gardner WN, Wessely S. Hyperventilation and chronic fatigue syndrome. Q J Med. 1994 Jan;87(1):63-7. http://www.ncbi.nlm.nih.gov/pubmed/8140219