An out-of-hospital perspective on hyperventilation syndrome

Hyperventilation and tachypnoea both involve breathing at an increased rate. There are a variety of causes of hyperventilation and conditions associated with it, including acute and chronic hyperventilation syndrome (HVS). The characteristics of HVS are not well defined. It results from a reduction in carbon dioxide and altered pH in the body from overbreathing. Symptoms vary between individuals but usually include altered sensations in the extremities, nausea and headache. Diagnosing patients with this condition can be difficult; diagnostic tools include the hyperventilation provocation test, voluntary overbreathing, the Nijmegen questionnaire and the exclusion of physiological causes in the acute situation. There are various prehospital patient presentations and differentiating between potential underlying causes is vital to appropriate treatment and patient safety. Treatments vary in nature, depending on the desired effect and the clinician's scope of practice. Some aim to reduce the frequency and intensity of attacks while others combat the attack when it strikes. This review briefly discusses some treatments available to a clinician with a basic skill level. There is a lack of evidence in this area, and research with a focus on the out-of-hospital environment is recommended. Because of controversy over existing research regarding the definition of HVS, a review of all sources was conducted to produce a definition. This suggests that HVS is a collection of physical and biochemical reactions from an unnecessarily increased respiratory rate that occurs because of an unknown or benign aetiology which can be triggered by anxiety in the absence of other external factors.