Johns Hopkins researchers say that several factors may explain why a stay in an intensive care unit (ICU) leads many patients to report depression after they go home, including a high level of organ failure and being given relatively high doses of a benzodiazepine sedative.
"The hope is that as we learn more about the effect of variations in ICU care, we'll be able to predict which patients are most susceptible to depression, prevent some depression by changing ICU practices, and make sure patients receive adequate mental health monitoring after discharge," says Dr. O. Joseph Bienvenu, an associate professor in the Department of Psychiatry at the Johns Hopkins University School of Medicine.
To figure out whether certain aspects of critical illness and ICU care swung patients toward depression, he and his colleagues evaluated patients recently admitted to one of 13 ICUs located at four teaching hospitals in Baltimore, Maryland.
Bienvenu revealed that each of the patients was treated for acute lung injury (ALI), a respiratory distress syndrome in which patients typically require invasive interventions in the ICU, including use of ventilators.
His team followed 160 patients who had survived at least six months after their ALI diagnosis, and took note of a variety of features of each patient's status and care while in the ICU, such as severity of organ failure, their blood sugar levels and other lab work, and the amount and type of sedative they received.
Six months after the patients' ALI diagnosis, they were given a questionnaire to measure depressive symptoms ranging from none to possible or probable clinical depression.
Bienvenu revealed that 26 percent of the 160 patients scored above the threshold for possible depression.
He said that as compared to other ALI survivors, the depressed patients were more likely to have suffered greater severity of organ failure, and to have received 75 mg or more of a benzodiazepine sedative daily.
He believed that longer physical recovery period after ICU discharge, among patients treated for severe organ failure, might be a cause of depression.
However, his team were still unclear as to the association between depression and ICU benzodiazepine dose.
Given that such a relationship has never been seen with other types of sedatives commonly prescribed to in the ICU, the researchers believe that high doses of benzodiazepine alone may somehow cause depressive symptoms.
"This is clearly a question that needs further study," says Bienvenu.
A research article on the study has been published online in Critical Care Medicine.