Clinical Determinants of Abnormalities in Pulmonary Functions in Survivors of the Adult Respiratory Distress Syndrome

Abstract

Pulmonary function tests (PFTs) were performed in 39 survivors of the adult respiratory distress syndrome (ARDS) in whom clinical data had been prospectively collected during the acute episode. PFTs stabilized within 6 months of the episode and had returned to normal in most survivors. Persistent abnormalities were found after 6 months in diffusing capacity (14 of 23 patients, 61%), vital capacity (10 of 23 patients, 43%), and total lung capacity (five of 24 patients, 21%). To clarify the mechanisms underlying these persistent abnormalities, we attempted to correlate long-term PFT outcomes with estimates of the severity of initial lung injury as assessed from clinical data and with other features of the patient's course. The severity of lung function impairment during the first 3 days of ARDS was not related to long-term PFT values. However, a lower DLCO was related to a higher AaDO2, higher pulmonary artery pressure, and worse radiographic appearance on Days 4 through 7 and to the occurrence of sepsis. A lower FVC was related to higher pulmonary vascular resistance in Days 4 through 7 of ARDS. Long-term values for FVC and TLC were directly related to increasing levels of PEEP applied from Days 4 through 7 of ARDS in patients with peak airway pressures less than 50 cm H2O. Long-term abnormalities of pulmonary function of survivors of ARDS were not related to initial lung impairment but were directly related to persistence of impaired lung function during the acute episode. Recovery of lung function may also have been directly related to therapeutic modalities such as PEEP and impaired by the occurrence of sepsis.

Long-term outcomes in survivors of acute respiratory distress syndrome ventilated in supine or prone position

“…Our patients received mechanical ventilation following the recommendation, which may have prevented ventilator-induced lung injury [41,42], while mean duration of mechanical ventilation was similar to in previous studies [4,7]. In addition to impairment on spirometric testing, reduction in DLCO has been found in surviving ARDS patients, with frequency between 40% and 80% [4,7,9,10,39,43]. This persistent impairment in gas transfer is probably due to injury at capillary level, which promotes thickening in alveolar capillary interfaces, pulmonary fibrosis, and pulmonary vascular remodeling.…”

Predicting the Presence of Pulmonary Function Impairment in Adult Respiratory Distress Syndrome Survivors

“…Previous information has sug gested that most ARDS survivors recovered near normal pulmonary function within 12 months of the ARDS event [26]. Recent reports suggest some survivors have moder ately or severely impaired pulmonary function after ARDS [1][2][3]. Some of the therapies and support tech niques previously used and undercurrent investigation for ARDS may have contributed to this residual respiratory impairment.…”

“…In ARDS survivors studied more than 6 months after ARDS, Peters [2] reported persistent im pairment in 14 of 23 (61%) survivors for diffusing capacity, 10 of 23 (43%) for vital capacity and 5 of 24 (21%) for total lung capacity. Correlations have been described between physiologic indices of ARDS severity and pulmonary func tion after recovery [2,3].…”

“…In ARDS survivors studied more than 6 months after ARDS, Peters [2] reported persistent im pairment in 14 of 23 (61%) survivors for diffusing capacity, 10 of 23 (43%) for vital capacity and 5 of 24 (21%) for total lung capacity. Correlations have been described between physiologic indices of ARDS severity and pulmonary func tion after recovery [2,3]. Recently, wc observed that sever ity of hypoxemia during ARDS correlates with percent predicted FVC, TLC and Dlco after ARDS [4], Available evidence suggests that maximum recover)' of lung function is complete 1 year after ARDS onset [2,5].…”

“…Correlations have been described between physiologic indices of ARDS severity and pulmonary func tion after recovery [2,3]. Recently, wc observed that sever ity of hypoxemia during ARDS correlates with percent predicted FVC, TLC and Dlco after ARDS [4], Available evidence suggests that maximum recover)' of lung function is complete 1 year after ARDS onset [2,5]. Prediction of which survivors will be impaired after ARDS is difficult because impaired survivors are no more likely to have symptoms than unimpaired survivors, and the clin ical features of ARDS do not predict subsequent function reliably [6], In this study, wc developed a scoring system to predict impairment of pulmonary function in ARDS survi vors.…”