Konno-Mead Analysis of Ribcage-Abdominal Motion during Successful and Unsuccessful Trials of Weaning from Mechanical Ventilation^1–3

Abstract

Respiratory muscle fatigue is considered a common cause of weaning failure but its detection is hampered by the lack of a satisfactory diagnostic test. Abdominal paradox has been proposed as a valuable clinical index of fatigue and thus its presence may lead to curtailment of weaning trials. However, sensitivity and specificity of this sign as a predictor of weaning outcome is unknown. We hypothesize that abnormal ribcage-abdominal (RC-Ab) motion is a common finding in the early stages of weaning and its presence does not inevitably imply an unsuccessful weaning outcome. We tested this hypothesis in patients undergoing a weaning trial: one group had a successful weaning outcome and were extubated (n = 10) and the other group failed the trial (n = 7). Normal RC-Ab motion was separately characterized in 17 healthy subjects. Employing a calibrated respiratory inductive plethysmograph, quantitative assessment of asynchrony and paradox was obtained by computing several indices from series of breaths at fixed time periods using the Konno-Mead method of analysis. During the weaning trial, both groups of patients displayed significant increases in asynchrony and Ab paradox compared to normal values. As a group, patients who failed the trial displayed significantly greater asynchrony and paradox of the RC and Ab than patients with a successful outcome. However, there was considerable overlap between the individual patients in the 2 study groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Stratification of difficulty in weaning

“…On multivariate analysis, however, hypercapnia-and not f/V T -was associated with prolonged weaning. This result is expected because f/V T is a critical determinant of PaCO 2 [7].…”

“…An additional mechanism responsible for decreased alveolar ventilation and hypercapnia is a decrease in respiratory drive [14]. Limited and indirect evidence, however, suggests that most patients who fail a weaning trial have an increase in respiratory motor output [7,14].…”

A Randomized Controlled Trial to Compare Adaptive Support Ventilation and Pressure Support Ventilation for Weaning COPD Patients

“…Patients with APACHE II score of 15-30. (27,28) , the studied patients were randomly enrolled using the sealed envelope method into two equal groups as shown in figure 1.…”

The art and science of non-invasive ventilation

“…Patients with unsuccessful weaning from mechanical ventilation are likely to develop during a spontaneous breathing trial a rapid and shallow breathing pattern (52), with progressive worsening of dynamic lung elastance, intrinsic PEEP (PEEPi), inspiratory resistance, and work of breathing (53). All these changes are not present when patients successfully tolerate a spontaneous breathing trial.…”