Medicine of the Future in America

Automatic Weaning From Mechanical Ventilation Using an Adaptive Lung Ventilation Controller: Results

In addition to these parameters, we also measured an index of rapid shallow breathing (RSB=f/VT)n and the level of pressure support (APinsp) subsequent to placing the patients on the ALV controller. The 27 patients studied ranged in age from 20 to 74 years (mean, 44 years) and had been ventilated in our RICU for respiratory failure for 1 to 30 days (mean, 7.7 days). We included nine patients with normal lungs (mean Apache II score on admission: 13.2), nine patients with parenchymal lung disease (mean Apache II score on admission: 14.6) and nine patients with severe chronic obstructive lung disease (mean Apache II score on admission: 18.7). Patient data and primary diagnoses are given in Table 1.
Baseline data results are summarized in Table 2. The only statistically significant difference in any of the parameters measured at baseline and between the three patient disease groups was a lower end expiratory airway pressure (2 cm H2O) in the COPD group. Although VC, Rtot, RC, IPD, and slope CO2 were noticeably different between the disease groups, the differences did not reach statistical significance due to the application of the Bonferroni correction.
The outcome of the weaning is depicted in Figure 2. In the group with normal lungs, the ALV controller reduced the respiratory support to the minimum within 30 min. Eight patients were successfully weaned whereas one patient who had been septicemic and had residual muscle weakness became tac-hypneic some hours after the wean, requiring further ventilation, and he was documented as having failed the wean. In the group with parenchymal lung disease, seven patients were successfully weaned; one patient who had reduced pulmonary compliance after septicemia and transfusion-related acute lung injury failed the wean, while one patient who required reventilation for worsening hypoxemia 24 h after being weaned and was subsequently confirmed to have a fibrosing alveolitis was not able to be assessed. buy birth control

Table 2—Selected Baseline Data: Median Values for Each Group of Patients (N=27)

PaC02,kPa Pa02,kPa fmech,/min fspont,/min Vt,mL Vm,L/min Pawmax,cmH20 Paw-ee,cnH20 VC,mL
Normal 4.25 22.02 10 2 501 8.4 21.1 5.5 1,200
Parenchymalabnormality 4.43 19.2 10 11 519 9.4 23.9 7 1,000
COPD 4.29 13.4 10 1 623 7.5 24.7 2* 900
Rtot,cm/L/s P0.1,cmH20 RC, s IPD,mj PE,Ns/m2 VdS,mL V’gA,L/min Fco2et, vols % slopeC02, vols% /L
Normal 8.2 -0.39 0.82 9.7 72 90 6.9 3.9 1.45
Parenchymalabnormality 5.9 -0.04 0.75 16.17 62 114 6.7 3.6 3.2
COPD 14.3 0 0.64 3.8 36 102 6.1 3.86 2.87


Figure 2. Truth diagram for outcome of weaning.

This entry was posted in Pulmonary function and tagged chronic obstructive lung disease, feedback, mechanical ventilation, respiratory failure, weaning.
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