HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:
Guest Access | Sign In via User Name/Password

This Article Full Text Free Full Text (PDF) Free Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Article Archive Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Holliday, J. E. Articles by Lippmann, M. Search for Related Content PubMed PubMed Citation Articles by Holliday, J. E. Articles by Lippmann, M.

Reduction in Ventilatory Response to CO₂ With Relaxation Feedback During CO₂ Rebreathing for Ventilator Patients^*

^* From the Veterans Affairs Medical Center, St. Louis MO.

Correspondence to: Jerome E. Holliday, PhD, Medicine Services, 151JC, VA Medical Center, 915 N Grand Blvd, St. Louis, MO 63106; e-mail: HollidayJEH{at}msn.com

Background: Previous studies have shown that relaxation biofeedback reduced the amount of time spent receiving ventilation for difficult-to-wean patients.

Objective: The present study was begun to test the hypothesis that the underlying mechanism of biofeedback ventilator weaning was the reduction of neural respiratory drive (NRD).

Design: Prospective.

Setting: Pulmonary Medicine division in a Veterans Affairs hospital and the St. Louis Regional Medical Center.

Subjects: Twenty-four patients who were receiving mechanical ventilation were randomly assigned to either the biofeedback group or the control group.

Intervention: Respiratory relaxation feedback (RFB) was administered while a single variable, PaCO₂, was inputted to the respiratory control system and the output was measured. While rebreathing 7% CO₂/93% O₂, the biofeedback group received a CO₂ trial session and a CO₂ RFB session, and the control group received a CO₂ trial session and a CO₂ no-feedback (NFB) session.

Measurements and results: There was a significant (p < 0.05) reduction in respiratory and EEG parameters for the RFB group at maximal end-tidal CO₂ (mean [± SE], 70 ± 0.2 mm Hg) between the CO₂ trial and the CO₂ RFB session compared to the control group where there was no significant difference between the results of the CO₂ trial and the CO₂ NFB session. The mean values for the CO₂ trial and CO₂ RFB session for the biofeedback group were as follows: occlusion pressure 0.1 s from the onset of inspiration, 8.42 ± 1.08 and 6.48 ± 0.78 cm H₂O (which reflects NRD), respectively; minute inspiratory ventilation, 15.84 ± 0.81 and 13.91 ± 0.72 L/min, respectively; mean inspiratory flow, 670 ± 2.28 and 581 ± 35 mL/s, respectively; respiration rate, 32 ± 2.28 and 31.2 ± 2.58 breaths/min, respectively; and chest background electromyography, 4.89 ± 0.71 and 3.54 ± 0.54 µV, respectively. The mean electroencephalograph outputs for the CO₂ trial and CO₂ RFB session for the biofeedback group were as follows: mean EEG frequency, 14.78 ± 0.98 and 13.06 ± 0.59 Hz, respectively; and beta EEG power, 3.1 ± 0.03 and 2.39 ± 0.19, µV², respectively; and gamma EEG power, 2.96 ± 0.34 and 2.24 ± 0.24 µV², respectively.

Conclusion: We conclude that the decrease in respiratory parameters reflecting NRD induced by RFB represents a key mechanism for the previously demonstrated effectiveness of biofeedback in reducing weaning time from mechanical ventilation.

Key Words: CO₂ rebreathing • EEG • neural respiratory drive • ventilator • weaning