The odds of
surviving cardiac arrest in the hospital are lower during the
night shift, according to one of the largest studies of its
kind, reported at the American Heart Association’s Scientific
Sessions 2003.
“Hospitals may be
less prepared to identify and respond to cardiac arrest during
the night shift, when overall staffing is typically at its
lowest,” said Mary Ann Peberdy, M.D., lead author of the study
and assistant professor of internal medicine and emergency
medicine at Virginia Commonwealth University Health System in
Richmond, Va.
Cardiac arrest is
the abrupt loss of heart function. The most common cause of
cardiac arrest is an abnormal heart rhythm known as ventricular
fibrillation (VF). VF can be treated with a defibrillator,
which can correct the abnormal heart rhythm.
The American
Heart Association estimates that about 95 percent of cardiac
arrest victims die before reaching the hospital. In cities
where cardiopulmonary resuscitation and defibrillation are
provided within three to five minutes, survival rates are as
high as 49 percent to 74 percent.
“However, little
is known about survival of patients who are already in the
hospital when they suffer from cardiac arrest,” Peberdy said.
Researchers used
records from 250 hospitals participating in the National
Registry of Cardiopulmonary Resuscitation (NRCPR). They
evaluated 17,991 cardiac arrests that occurred in hospitalized
adults between January 2000 and June 2002.
The patients’
average age was 68. Seventy-two percent were white, 21 percent
were black, 5 percent were Hispanic, and 2 percent were of other
ethnic/racial origin.
Peberdy
categorized the cardiac arrest events by when they occurred
during the most common work shifts: day (7 a.m.–3 p.m.), evening
(3 p.m.–11 p.m.) and night (11 p.m.–7 a.m.). They used a
statistical analysis called ANOVA, or ANalysis Of VAriance to
compare rates of cardiac arrest and time of shift. There was no
statistically significant difference in the occurrence of
cardiac arrest by shift. In addition, neither age nor
ethnicity/race corresponded to the shift in which cardiac arrest
occurred.
However, patients
whose cardiac arrest occurred at night had a lower survival rate
(41 percent) than those whose event occurred during the day (49
percent) or evening (48 percent). The survival was the same for
those treated in the intensive care unit (ICU) or a non-ICU
area.
Eighteen percent
of those who had cardiac arrest in the day or evening survived
until discharge, while only 13 percent of those with cardiac
arrest during the night survived to discharge.
The researchers
also found that cardiac arrest was recorded on hospital monitors
and/or witnessed much less often at night – in 82 percent of
events compared to 89 percent during both the day and evening
shifts.
“This study draws
attention to process issues in in-hospital cardiac arrest
responses,”
Peberdy said.
“We hope the information will lead to more hospitals evaluating
their staff training and response to cardiac arrest at all times
during the day and especially at night, and developing better
mechanisms for identifying cardiac arrest in the hospital.”
Co-author is
Joseph P. Ornato, M.D.