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

Efficacy of Positive vs Negative Pressure Ventilation in Unloading the Respiratory Muscles: Results (3)The other measures of diaphragmatic activity also demonstrated greater reduction during PPV. Figure 3 and Table 1 illustrate the reduction in the PTI, peak Pdi, and CV-Vt. The reduction of PTI during NPV was different from QB (58 percent, p = 0.05) and the reduction during PPV was different from both QB (29 percent, p = 0.01) and NPV (p = 0.05). The peak Pdi was similarly reduced during PPV to 47 percent of baseline (p = 0.01). The CV-Vt during PPV was significantly lower (3 percent) when compared to NPV (CV-Vt=13 percent) and QB (CV-Vt =18 percent) (p = 0.01).
Figure 4 shows the relationship between the change in etC02 and iEMG during both PPV and NPV Both combined (PPV + NPV) and separate analysis failed to show a significant relationship between the two variables (r=0.210, p = 0.349). birth control pills
The relationship between iEMG and peak Pdi and PTI was examined. During QB, there was a significant relationship between iEMG and both indices (r = 0.818 and r = 0.801, respectively, p<0.01). There was also a significant relationship between the change in iEMG and change in PTI during NPV and PPV (y = 0.90x- 23.04; r = 0.88, p<0.01) (Fig 5).

Table 1—Means of Breath-by-Breath Sampling during Last Three Minutes of Each Study Session Expressed as Mean ± SD

Ve,* L/min Peak Pdi,t cm H20 ETCOa,t %
Normals (n = 5)
QB 7.3± 1.3 16.8 ±5.2 5.8 ±0.5
PPV 8.6± 1.2 8.2±4.4 5.0±0.4
NPV 7.8± 1.3 11.3±6.7 5.4±0.4
COPD (n = 6)
QB 9.9± 1.7 24.6±7.3 4.7±0.6
PPV 12.7 ±2.8 11.4±8.0 4.0±0.7
NPV 10.6± 1.3 19.8±6.7 4.6±0.6

Figure_4

Figure 4. Scattergram compares the change in iEMG and the change in etC02 for all subjects. No significant relationship was found. Symbols as defined in Figures 2 and 3.

Figure_5

Figure 5. Significant relationship between the change in iEMG and the change in PTI (p<0.01) for all subjects. Symbols as defined in Figures 2 and 3.


Category: Lung function

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