Efficacy of Positive vs Negative Pressure Ventilation in Unloading the Respiratory Muscles: Methods (3)

Efficacy of Positive vs Negative Pressure Ventilation in Unloading the Respiratory Muscles: Methods (3)The integration continued until an expiratory volume was detected. This integration had no “leak” associated with it since the period of integration was certain, and there was no need for integrating over the entire EMG record, as is the case with the analog integrators. From this standpoint, our method of integrating the EMG is an exact software implementation of the analog integrator used by Bigland and Lippold. (2) The software marked and removed some of the cardiac electrical activity present in the EMG signal (such as the QRS complex). To accomplish this, we wrote a simple algorithm that searched in a moving window of length 0.4 s for epochs of very high impulse-like electrical activity. This portion of the signal was marked (mean duration = 120 ms) and replaced by the average of an equal length EMG period that immediately followed.
In summary, after the digitized record of an experiment was processed by the software, the following variables were printed out on a breath-by-breath basis: Vt, fb, Ve, Pes, Pga, Pdi, peakPdi, PTI, and iEMG.
Study Protocol
After adjustments were made to ensure optimal pressure and EMG signals, all subjects were studied with the following protocol: Initial measurements were made during 10 minutes of quiet breathing (QB). Breath-by-breath samples obtained during the last 3 minutes of QB were considered baseline values. buy flovent inhaler
Subsequendy, each subject received 15 minutes of both NPV and PPV Negative pressure ventilation was applied via a Thomson Maxivent ventilator (Puritan-Bennett, Boulder, CO) attached to a poncho-wrap. A plastic frame, which allowed sufficient room for chest expansion, was positioned over the chest, and the wrap was placed over this frame.


Category: Lung function

Tags: neuromuscular, neuromuscular disease, patients copd, ventilatory muscle