Viral Induced Hypersecretion of Mucous (VIper): Proposal for a Distinct Phenotype of Viral Induced Lower Respiratory Tract Infection in Children.

Some children with an acute viral lower respiratory tract illness present with a phenotype that overlaps with, but is distinct from, that of asthma. These children have shortness of breath with increased work of breathing, wet cough, hypoxia out of proportion to the work of breathing, incomplete resolution of hypoxia with supplemental oxygen, worsening of oxygen saturation after salbutamol and improvement of oxygen saturation with coughing. The pathophysiology appears to relate to relate to excess mucous secretion in the airways causing ventilation:perfusion (V/Q) mismatching, which is then exacerbated by salbutamol use. A descriptive label for this condition is Viral Induced hypersecretion of mucous (VIper). Since this has yet to receive formal recognition as a subtype of viral induced lower respiratory tract infection in children, there are no published therapeutic trials of management. This letter details the proposed pathophysiological mechanisms of mucous hypersecretion and V?Q mismatching. The value of considering VIper as a distinct subset of viral lower respiratory tract infection is to prevent harmful treatments and offer the opportunity for prospective trials of effective therapies.