Evaluation of a new weaning index based on ventilatory endurance and the efficiency of gas exchange. Am Rev Respir Dis 1991 Sep;144(3 Pt 1):531-7
Date
09/01/1991Pubmed ID
1892291DOI
10.1164/ajrccm/144.3_Pt_1.531Scopus ID
2-s2.0-0026005267 (requires institutional sign-in at Scopus site) 81 CitationsAbstract
We hypothesized that the ventilatory capacity needed to wean from mechanical ventilation (mv) depends on two variables: ventilatory endurance and the efficiency of gas exchange. We also hypothesized that these variables could be assessed from data readily available at the bedside, including tidal volume (VT) on mv and during spontaneous breathing (sb), ventilator peak inspiratory pressure (Ppk), and patient negative inspiratory pressure (NIP). Ventilatory endurance was evaluated using a modified pressure-time index: PTI = TI/Ttot x Pbreath/NIP, where Pbreath = Ppk x VTsb/VTmv. Defining VE40 as the minute ventilation needed to bring PaCO2 to 40 mm Hg, the efficiency of gas exchange was evaluated by calculating VE40/VTsb = (VE x PaCO2)mv/VTsb x 40. Because high levels of inspiratory effort might cause patients to reduce VTsb and thereby compromise CO2 elimination, we devised a weaning index (WI) that combines ventilatory endurance and the efficiency of gas exchange: WI = PTI x (VE40/VTsb). The study population comprised 38 patients with chronic obstructive pulmonary disease, adult respiratory distress syndrome, pneumonia, neuromuscular disease, and miscellaneous other conditions. They had been mechanically ventilated more than 3 days and were considered by clinical criteria to be ready for weaning. Of 46 weaning trials, 19 were successful, 2 were partially successful, and 25 failed. PTI and VE40/VTsb were higher in patients who failed (p less than 0.05), but neither variable alone had sufficient sensitivity or specificity to predict the outcome of weaning trials accurately.(ABSTRACT TRUNCATED AT 250 WORDS)
Author List
Jabour ER, Rabil DM, Truwit JD, Rochester DFMESH terms used to index this publication - Major topics in bold
AdolescentAdult
Aged
Aged, 80 and over
Evaluation Studies as Topic
Humans
Lung Diseases, Obstructive
Middle Aged
Neuromuscular Diseases
Pneumonia
Pulmonary Gas Exchange
Respiratory Insufficiency
Respiratory Mechanics
Respiratory Muscles
Ventilator Weaning
