Comparison of two different modes for noninvasive mechanical ventilation in chronic respiratory failure: volume versus pressure controlled device.
The most commonly used mode of noninvasive mechanical ventilation (NMV) is volume-controlled intermittent positive pressure ventilation (IPPV). Pressure support ventilation has recently become increasingly popular, but its merits have not been clearly defined. In an open, nonrandomized follow-up study, we evaluated two modes of NMV, volume-controlled (IPPV) and pressure-controlled ventilation (PCV) over 6 months in 30 consecutive patients (24 males and 6 females, aged 49 +/- 19 yrs) with chronic respiratory failure (CRF). The baseline assessments comprised both physiological and subjective data. In all cases, nasal IPPV was initially administered for 1 month, followed by a second month of nasal PCV. Thereafter, responders or nonresponders to PCV were defined according to the patients' subjective symptom score and/or the recurrence of hypercapnia. During the IPPV phase, in all but two patients the subjective and objective parameters improved significantly. During the following 1 month PCV phase, stabilization was maintained in 18 patients ("responders"), while 10 patients were defined as "nonresponders". In nonresponders, hypercapnia increased (arterial carbon dioxide tension (Pa,CO2): 5.7 +/- 0.4 to 6.6 +/- 0.5 kPa; p < 0.05) and symptom scores decreased. Compared with responders, nonresponders had a lower mean nocturnal arterial oxygen saturation (Sa,O2) (p < 0.05) and a higher daytime Pa,CO2 (p < 0.05) at baseline. We con clude that the majority of patients suffering from chronic respiratory failure who are initially satisfactorily ventilated with intermittent positive pressure ventilation may also be adequately maintained with pressure-controlled ventilation. However, there is a subgroup with more severe chronic respiratory failure at baseline, in whom pressure-controlled ventilation is inadequate. After 4 weeks of treatment with pressure-controlled ventilation, the subjective scores and the arterial carbon dioxide tension values reliably distinguished between long-term responders and nonresponders to pressure-controlled ventilation.
Schönhofer
B
B
Krankenhaus Kloster Grafschaft, Zentrum für Pneumologie und Allergologie, Schmallenberg-Grafschaft, Germany.
Sonneborn
M
M
Haidl
P
P
Böhrer
H
H
Köhler
D
D
D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D002908:Chronic Disease; D005069:Evaluation Studies as Topic; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000209:etiology / Q000628:therapy; D007385:Intermittent Positive-Pressure Ventilation; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012008:Recurrence; D012074:Remission Induction; D015203:Reproducibility of Results; D012131:Respiratory Insufficiency / Q000097:blood / Q000209:etiology / Q000628:therapy*
D002245:Carbon Dioxide; D010100:Oxygen