When investigating a patient's first hyperventilation attack, it is important to rule out serious diseases that may cause hyperventilation.
In the basic evaluation of any patient with hyperventilation the following examinations should be performed: basic blood count with platelet count, blood glucose, serum calcium, thyroid function (TSH, free T4), chest x-ray and ECG. If no other disease that would explain the symtoms can be found, attention should be placed on the treatment of panic disorder.
Definitions
Hyperventilation means increased alveolar ventilation causing a decrease in arterial blood pCO2, which in turn causes neurological symptoms and manifestations induced by vasoconstriction.
Hyperventilation-type symptoms are not necessarily connected with blood gas disturbances: e.g. in panic disorder, the patient may have a feeling that he/she does not get enough air and is therefore gasping for breath but is actually not hyperventilating.
Some patients get the symptom during physical exertion, or it may be related to a change in posture.
In practice hyperventilation syndrome means psychogenic recurring hyperventilation which often is connected with panic disorder Anxiety Disorder. Hyperventilation may, however, also be a symptom in many somatic diseases.
If oxygen saturation is low even though the patient hyperventilates, the cause is usually an organic disease, but normal oxygen saturation does not exclude an organic disease.
Arterial or capillary blood sample
During an acute attack, alkalosis and low pCO2 support the diagnosis.
Hyperventilation test
If voluntary hyperventilation causes the familiar symptoms, the diagnosis is supported and the patient can better understand the pathophysiology of the symptoms.
Hyperventilation predisposition can be investigated by spiroergometry. In this case, an orthostatic test with respiratory gas monitoring is often done to complement the exercise test.
Chest x-ray
ECG, basic blood count with platelet count, blood glucose, serum calcium, thyroid function (TSH, free T4)
Hyperventilation may, by an unknown mechanism, cause similar ECG changes to those seen in ischaemia (ST-segment depression and T-wave negativity).
In suspicion of pulmonary embolism: see investigation strategy in the article Pulmonary Embolism.
Treatment
Causative treatment
Treatment of acute psychogenic hyperventilation
Calming the patient and making the patient talk is often helpful.
Breathing into a paper bag in an acute situation has been mostly abandoned.
Peroral diazepam either as tablets or as solution is given if needed.
Try to identify the triggering factor and make a plan of treatment for the patient.
In specialized care, the patient may also be referred to a physiotherapist specialized in breathing education.
Boulding R, Stacey R, Niven R, et al. Dysfunctional breathing: a review of the literature and proposal for classification. Eur Respir Rev 2016;25(141):287-94.