Another reason to be wary of a hospital stay- a new study shows that patients who survive intensive care units in hospitals are at high risk for developing post-traumatic stress disorder (PTSD).

PTSD is in the news most often in relation to combat veterans, but researchers from the Johns Hopkins University School of Medicine found that one in three people who survived an intensive care unit (ICU) stay for acute lung injury showed PTSD symptoms that lasted up to two years.

Acute lung injury (ALI) is a condition marked by excessive fluid in the lungs and frequent multi-organ failure. It can involve airway collapse, and often requires the use of a mechanical ventilator to stay alive.

Since acute lung injury is a prime example of critical illness, the researchers believe that a high rate of PTSD for acute lung injury patients suggests that is also common to see PTSD in ICU survivors with other conditions.

"We usually think of PTSD as something you develop if you go to war, are sexually assaulted or suffer a similar emotional trauma," says Dr. Dale Needham, senior author of the study published online in Psychological Medicine on February 27.

"Instead, it may be as common, or more common, in ICU patients as in soldiers, but it's something many doctors -- including psychiatrists -- don't fully appreciate."

PTSD is an anxiety disorder that can develop after people experience a traumatic or life-threatening event. People suffering from PTSD may feel extremely threatened or stressed long after the event.

PTSD symptoms include re-experiencing the traumatic event in flashbacks and nightmares, avoidance of situations that trigger reminders and feeling emotional numbness, and hyperarousal, which includes irritability, having trouble sleeping, and being easily startled. A diagnosis is made after the symptoms do not go away after one month and interfere with daily life.

"It is very common for people who survive bad ICU stays to be subsequently crippled by the post-traumatic stress disorder (PTSD) that develops," said Dr. Charles Raison, a psychiatrist at Emory University Medical School. "The longer the PTSD continues, the harder it is to treat."

PTSD in hospital patients is often complicated by the delirium they experienced while in the ICU.

It can be horrible enough to remember being attached to breathing machines and given sedative and narcotic drugs while your life was threatened, but PTSD in ICU patients can involve memories of terrifying hallucinations and delusions that never occurred.

"One woman thought her husband and the nurse were plotting to kill her," recalled Dr. O. Joseph Bienvenu, leader of the study.

PTSD can slow patients' recovery from critical illness, impairing quality of life long after they leave the ICU and keeping victims from returning to daily life.

"Physical weakness usually gets better, but these mental symptoms often just linger," says Bienvenu. "We need to pay more attention to preventing and treating PTSD in these patients."

Almost 1 million patients in the United States are hooked up to ventilators in a hospital ICU each year, and approximately 200,000 develop acute lung injury, usually because of infection.

In healthy people, the lungs allow the easy exchange of air that lets oxygen enter the bloodstream and carbon dioxide exit the body. In acute lung injury patients, the normally dry lungs fill with fluid and become heavy and soggy.

The Johns Hopkins researchers behind the study observed 520 mechanically ventilated patients with acute lung injury, who were recruited from 13 ICUs at four Baltimore hospitals between 2004 and 2007. 53% survived their hospitalization, and 186 of the patients had at least one research visit over the subsequent two-year follow-up period.

The study found that 66 of the 186 patients (35%) had diagnosable symptoms of PTSD, with the greatest onset of PTSD symptoms occurring within three months. 62% of the survivors who developed PTSD still had symptoms after two years, and half of that group was taking psychiatric medications. 40% saw a psychiatrist within two years of being hospitalized in the ICU with acute lung injury.

The researchers also found that patients who had depression before their hospitalization were twice as likely to develop PTSD, and that they were more likely they were to develop PTSD with ICU stays that were longer.

Patients who were given high doses of opiate drugs during their ICU stay, along with those who had sepsis, a severe toxic response to infection, were also more likely to develop PTSD after leaving the hospital.

According to a statement from Johns Hopkins, the delirium often associated with ICU stays and post-ICU PTSD may be partially due to inflammation caused by sepsis. The inflammation may lead to a breakdown in the blood-brain barrier, which alters the impact on the brain of narcotics, sedatives and other drugs commonly prescribed in the ICU.

Patients given corticosteroids while in the ICU were less likely to develop PTSD, which may support research that aims to treat PTSD symptoms with doses of cortisol.

Bienvenu believes that hospital patients who have the risk factors identified in this study need special attention. A positive step in ICU treatment protocol would be to educate patients who are at risk for sepsis or need to given opiate drugs, and let them and their primary care doctors about their increased risk for PTSD.

A next step for the Johns Hopkins team is to identify whether changing care in the ICU can reduce the incidence of PTSD for hospital patients.

Studies have shown that early physical rehabilitation for ICU patients can speed and amplify physical recovery, and Needham believes that "psychological rehab" now deserves attention for preventing PTSD in ICU patients.

One idea is the use of "ICU diaries." Bienvenu noted a European study that had nurses and family members record what was happening with patients every day they were in the ICU, in writing and with photographs.

A month after the patients left the ICU, the patients were able to see the diaries and be debriefed by a nurse. The simple intervention reduced symptoms of PTSD for hospital patients by helping them make sense of their ICU memories.