Respiratory Function after Paralysis of the Right Hemidiaphragm1

Abstract

We studied a 45-yr-old man with normal lung function before and 7 wk after right phrenic nerve crush. Total lung capacity, functional residual capacity, and forced vital capacity decreased with residual volume remaining unchanged. Static compliance was also unchanged. Ventilatory response to CO₂ (ΔVE/ΔPa_{CO2) was preserved, but P0.1 response to CO2 (ΔP0.1/ΔPaCO2) increased. Analysis of raw mouth pressure suggested that these responses were the result of a new rapid pattern of inspiratory pressure development. Regional washout was slowed on the side with paralysis, but the normal apex-to-base gradient of regional volumes was preserved. Inhaled ¹³³Xe boluses were distributed away from the side of paralysis, and bolus distribution changed relatively little with increased flow. These results suggested that in compensation for paralysis of a hemidiaphragm, a new pattern of inspiratory muscle recruitment developed, involving more rapid contraction of the remaining muscles of inspiration.}