Elevated blood lactate concentration in psychogenic hyperventilation

Background

An elevated blood lactate concentration is a classic marker of hemodynamic instability and tissue hypoperfusion. It is considered by most physicians as the hallmark and even signature of a life threatening underlying condition. After the sporadic observation of an elevated lactate value in patients with typical hyperventilation we decided to study systematically blood lactate concentration in these patients.

Methods

We included consecutive patients admitted to the emergency department with a history and clinical findings suggesting hyperventilation, either primary (psychogenic, panic attack) or secondary to a renal colic. In addition to a standard history taking, complete physical examination, laboratory screening, ECG and chest radiograph, arterial blood gases and venous lactate were measured by standard clinical laboratory methods.

Results

Twenty patients, 10 females and 10 males, mean age 36 years, were studied. Sixteen had psychogenic hyperventilation and four hyperventilated as a reaction to a typical renal colic. Lactate concentration was increased in 12 cases (> 2 mmol/l); in 3 of them a value of more than 4 mmol/l was found. The lactate value did not correlate with pH nor paCO₂.

Conclusion

An increased blood lactate concentration may be caused by hyperventilation, either primary pscyhogenic or secondary to intense pain. This latter finding is of particular importance for the clinical assessment of the patient presenting with acute abdominal pain in whom most physicians consider an increased lactate concentration as a sign of mesenteric ischemia.