A Physiological and Psychological Model of Idiopathic Hyperventilation

Abstract

Hyperventilation was first described in the middle of the 19^th century, with soldiers in the American Civil war complaining of symptoms originally thought to be cardiac in nature¹. However, these symptoms were later discovered to be identical to idiopathic hyperventilation. Since this time there has been limited published data and little consensus as to existence and cause of this condition. The symptomatology is varied; however the principle symptoms include shortness of breath, chest tightness and parasthesia. The physiological variables associated with idiopathic hyperventilation are disproportionate breathlessness and evidence of hyperventilation at rest and during exercise. A disorganised breathing pattern has also been described, with no relationship between the ventilatory response and the level of exercise. This altered physiological response has been suggested to be due to a neuromuscular disturbance. Patients with idiopathic hyperventilation (IH) have also been described to have an altered psychological profile. Soley and Shock² in 1938 reported a relationship between symptomatology consistent with IH and psychological factors. Lowry in 1967 suggested that IH was identical to hysteria, patients consider themselves physically inferior and have perfectionist traits³. Lum⁴ described the most comprehensive explanation of the physiological and behavioural aspects of this condition. He hypothesised that IH may be initiated by anxiety. This emotional state creates symptoms, which are perceived and interpreted by the patient. A vicious circle then ensues whereby patients interpret the symptoms as life threatening, this creates further anxiety with increased hyperventilation and symptomatology. Plum⁵ proposed a model of interaction of the motor behavioural pathway and metabolic pathway. The motor behavioural pathway functions in addition to the metabolic pathway