The Annals of Thoracic Surgery, Vol 58, 1718-1720, Copyright © 1994 by The Society of Thoracic Surgeons
Tidal volume and respiratory rate changes during CO2 rebreathing after lung transplantation
GD Trachiotis, SR Knight, MS Pohl, GA Patterson, JD Cooper and EP Trulock
Washington University Lung Transplant Group, Barnes Hospital Washington University School of Medicine, St. Louis, Missouri 63110-1093.
To evaluate the contribution of the respiratory pattern to the ventilatory
response after lung transplantation, we studied the changes in minute
ventilation, tidal volume, and respiratory rate during CO2 rebreathing in
14 patients with severe obstructive pulmonary disease, and compared them
with 10 normal subjects. Seven patients underwent a bilateral lung
transplantation and 7 patients had single-lung transplantation. Single-lung
transplant recipients increased their respiratory rate by the last
postoperative test compared with either preoperative or initial test
periods (0.38 +/- 0.13 versus 0.027 +/- 0.24 or 0.12 +/- 0.08
breaths.min-1.mm Hg-1; p < 0.005). Bilateral lung transplant recipients
showed a diminished ability to augment their respiratory rate by the last
postoperative test compared with either preoperative or initial test
periods (0.13 +/- 0.23 versus 0.54 +/- 0.25 or 0.25 +/- 0.29
breaths.min-1.mm Hg-1; p < 0.06). The restored ventilatory response by
the fourth postoperative week was due to a statistically significant
increase in tidal volume for both single and bilateral lung transplant
recipients. This study demonstrates that when lung transplant recipients
have an appropriate ventilatory response to CO2 rebreathing, single-lung
transplant recipients have a respiratory pattern similar to normal; whereas
the bilateral lung transplant recipients show the effects of total
pulmonary denervation. We conclude that the preserved ventilatory response
in lung transplant recipients is composed of a respiratory pattern that is
influenced by the presence or absence of vagal inputs.
