Recovery Rate and Prognosis in Older Persons Who Develop Acute Lung Injury and the Acute Respiratory Distress Syndrome

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The summary below is from the full report titled "Recovery Rate and Prognosis in Older Persons Who Develop Acute Lung Injury and the Acute Respiratory Distress Syndrome." It is in the 1 January 2002 issue of Annals of Internal Medicine (volume 136, pages 25-36). The authors are EW Ely, AP Wheeler, BT Thompson, M Ancukiewicz, KP Steinberg, and GR Bernard, for the Acute Respiratory Distress Syndrome Network.

What is the problem and what is known about it so far?

Elderly people are much more likely to develop respiratory failure and require the use of a respirator than younger people. On the other hand, the results of respirator use in the elderly do not appear to be as good as in younger people, but the exact relationship between age and outcome is uncertain. The National Heart, Lung, and Blood Institute (NHLBI) sponsored a large study on acute lung injury that leads to respiratory failure. The data were made available to other researchers for further analysis.

Why did the researchers do this particular study?

To find out how advancing age affects survival from acute lung injury and whether recovery takes longer in older patients.

Who was studied?

902 patients at 24 U.S. hospitals who participated in the NHLBI study between 1996 and 1999. Patients were included in the study if they had acute lung injury requiring use of a respirator, had low oxygen levels, and had a chest x-ray indicating that the respiratory problem was not due to heart failure. Of the participants, 729 were younger than 70 years of age and 173 were 70 years of age or older.

How was the study done?

Patients were evaluated each day to see if a respirator was still needed. Depending on the results of these evaluations, patients were allowed to breathe on their own for 5 minutes; if they did well, additional time off the respirator was prescribed and respiratory assistance was eventually discontinued. The time required to reach each landmark of recovery was recorded, as were the length of stay in the intensive care unit and the survival rate.

What did the researchers find?

Seventy percent of the younger patients and 40% of the older patients were discharged from the hospital alive within the first 180 days. At the time of entry into the study, the severity of lung injury was similar in both age groups. Older patients needed the respirator longer, were more likely to require reinstitution of respirator therapy after initial improvement, and stayed in the intensive care unit longer than younger patients. At 28 days after initiation of respirator use, the survival rate was lower with each decade of advancing age.

What were the limitations of the study?

Several nonrespiratory health problems (such as brain abnormalities) were not carefully monitored but could have affected the results. In addition, older patients may have been more likely than younger patients to have had life support withdrawn because of poor general condition. Furthermore, preexisting illness was difficult to take into account in interpreting the results.

What are the implications of the study?

Although elderly patients seem to recover initially from acute lung injury at a rate similar to younger patients, they are more likely to return to mechanical ventilation and are more likely to die of their acute lung illness. Age alone should not be used as a criterion to deny respirator care. Rather, more effort should be made to improve outcomes in elderly people who develop acute lung failure.