PERFUSION SAFETY IN AMERICA: RESULTS OF A NATIONAL SURVEY OF 671,290 CASES
A.H. STAMMERS, MSA, CCP
Geisinger Medical Center - Danville, Pennsylvania, USA
OBJECTIVES
1. To report the results of a national survey sent to all hospitals in the
United States in 1999.
2. Identify the most common perfusion accidents and the relative rate of
occurrence.
INTRODUCTION
Conduct of cardiopulmonary bypass (CPB) is a diverse understanding
influenced by numerous mechanical devices and variable patient responses.
Variety of conduction of CPB stems from a great diversity of practices and
techniques. The influence of these techniques on patient outcomes was not
apparent to the medical community until William Stoney’s published his survey
regarding accidents and techniques during CPB in 1979. Additional surveys were
patterned after the work by Stoney, but have attempted to address somewhat
disparate variables. Results from Stoney and Kurusz showed the overall
variability of perfusion techniques between institutions. Recent surveys have
shown an increase in use of CPB arterial line filters, bubble detectors, and low
level alarms but their effect is difficult to quantify because of the lack of
accident reporting.
Accident rates from Stoney and Kurusz studies showed one accident resulting in
serious injury or death per 1,000 open-heart procedures employing CPB. A recent
Australian survey reported that one accident was seen for every thirty-five CPB
procedures and reported one accident resulting in serious injury or death for
every 1,288 CPB procedures. Currently, there are no accident studies or data
pertaining to North American perfusionists. Accidents are still prevalent during
CPB. The survey served the purpose of identifying current CPB accident rates and
safety device utilization by cardiovascular perfusionists.
METHODS
A survey was developed by the Division of Clinical Perfusion Education, at
the University of Nebraska Medical Center, and mailed during the fall of 1998.
The initial results were presented in descriptive fashion at the January 1999,
American Academy of Cardiovascular Perfusion Meeting held in San Antonio, Texas.
A complete description of the survey methodology has been previously reported.
Briefly, a questionnaire was mailed to 1,030 chief perfusionists at all cardiac
centers in the United States as identified in Billian’s Hospital Blue Book. The
questionnaire was addressed to the chief perfusionist at each center performing
cardiac surgery. A cover letter was enclosed that stated instructions for
completing the questionnaire, and the respondent was asked to include data from
all hospitals in which coverage was provided. A self-addressed stamped envelope
was enclosed for the return mailing of the questionnaire. This process was
completed an additional two times at approximately six week intervals.
The questionnaire contained 80 questions in four
separate categories: Perfusionist Information, Hospital Information, Equipment
Information, and Perfusion Accidents. Perfusion accidents were described as
those that occurred either during CPB, or that had resulted from its utilization.
The Equipment Information section consisted of 36 questions that dealt with
specific devices used in perfusion. In this section, respondents were also asked
to answer whether or not they stopped using the device queried. If the
respondent answered that a particular piece of equipment was no longer in use,
then they were asked to state the basis of the decision, and were offered
options of “cost”, “ineffectiveness”, or “other”.
Data is initially presented in descriptive format. The results of device
utilization was then calculated as a percent of total completed surveys. Where
respondents reported discontinuation of a device, the percent reduction was
calculated as above. The number of responses in each of the three categories of
discontinuation was then divided into the total number discontinued to provide a
percent.
RESULTS
Of the 1,030 surveys sent, a total of 552 were returned (53.6%). 18
non-completed surveys were returned because of either no cardiac or perfusion
services were performed at that facility. An additional 10 surveys were omitted
because they contained either incomplete data or had data with questionable
accuracy. Therefore, a total of 524 surveys were included for data analysis, and
represents a 51.8% response rate. Each respondent was asked to report on whether
or not they were competing the survey for more than one hospital. If so, the
total number of hospitals that the respondent was reporting for was recorded.
136 respondents reported for 408 hospitals. The mean number of hospitals
reported by each multi-facility respondent was of 3.1 (median of 2.0). The total
number of hospitals represented in the survey was 797, or 78.8% of all
identified cardiac surgical facilities. Adult hospitals accounted for 407 of
respondents, 17 represented children hospitals, and 100 respondents stated their
institutions perform CPB on both adult and children. The type of hospitals that
performed cardiac surgery were as follows: 14.0% university, 24.1% private
for-profit, 52.3% private not-for-profit, 3.1% VA/Military, 2.1% Other such as
community or county.
CASE NUMBERS
The total number of cases reported during the two-year period was 671,290.
There were a total of 2,386 perfusionists accounted for in the survey. The mean
1997-1998 case-per-perfusionist number was 142.8. There were a total of 2,148
heart-lung machines reported in the perfusion departments at respondent
hospitals. Each hospital had an average of 2.67 heart-lung machines. Centrifugal
pumps were used by 49% of respondents while roller pumps were utilized by 44%.
The remaining 7% consisted of either the Rhone-Poulenc3 (2%) or a combination of
the three (5%).
SURGICAL PROCEDURES
Liver transplants were performed by 13.7% of respondents and other
transplant operations, such as heart and lung involved respectively 20.9% and
12.3% of respondents. Ventricular assist devices were performed by 86.5% of
respondents; minimally invasive surgery was performed in 79.3% of respondent
hospitals. Other procedures, which the perfusionists were responsible for, were
intraaortic balloon pumps (78.7%), autotransfusion (83.3%), and isolated limb
perfusion (11.4%).
SAFETY DEVICES
The most common perfusion safety devices were hand cranks (99.0%), arterial
line filters (98.2%), cardioplegia line pressure manometers (96.5%), and gas
line filters (95.9%). Arterial line filters along with one way purge lines were
used by 91.6% of responding perfusionists. Left ventricular vent lines were
reported by 82.8% of the respondents.
INCIDENTS
Protamine reaction (1:801 procedures) resulting in reheparinization and
reinitiating of CPB was the most frequently reported accident. Other common
accidents reported were coagulation problems such as DIC following CPB (1:811),
heater/cooler failure (1:1,862), air present in the circuit not reaching the
patient (1:1,957), and arterial dissection (1:2,310). Oxygenators required
changing out in 137 cases reporting failure. Coagulopathies (49 occurrences)
resulted in the highest number of deaths. Arterial dissections (39), protamine
reaction (23), clot present in circuit (12), and gas embolisms (8) were other
frequently reported causes of death during bypass. The two-year accident rate
was one for every 138 CPB procedures. For every 2,208 CPB procedures one serious
injury was seen and one death was reported for every 4,567 CPB cases. One
serious injury/death occurred for every 1,482 cases.
DISCUSSION
Since the 1986 reported accident rate of one serious injury or death per
1,000 procedures, the accident rate has fallen to one per 1,482 CPB procedures.
Equipment use changes since the previously reported surveys may have contributed
to this decline. Bubble oxygenator use was reported by 0.6 % of respondents in
the present study in contrast to the nearly equal utilization of membrane
oxygenator and bubbler presented in Kurusz’s 1986 study. In addition, the use of
arterial line filters (98.2%) has changed little since the perfusion practice
survey of 1993 (97.3%), but the use of arterial line filters has increased since
the 1986 survey (81.1%). Centrifugal pumps were used by 51% which may have
contributed to less arterial dissections, air embolisms, line separations, and
tubing ruptures. Accidents such as interrupted power or mechanical breakdown
were prevalent in the study but did not exhibit the results of death or serious
injury possibly due to the improved technology and maintenance of the heart lung
machines and auxiliary equipment. The present study exhibited an overall
incident rate of one accident for every 138 CPB procedures. This was much higher
than previous studies (1:1,000) which may be due to the inclusion of additional
accidents in our survey. The most common perfusion accidents were protamine
reactions and coagulation disorders such as DIC following bypass. This suggests
that perfusionists and manufacturers are challenged to address the current
problems of coagulation (1 per 811 bypass procedures) and the adverse effects of
protamine (1 per 801 bypass procedures). Since the most common accidents were
related to coagulation status illustrate the need for perfusionists to develop
improved methods of coagulation monitoring. Although protamine reactions and DIC
are not direct outcomes of perfusionist interventions, the perfusion community
must aid in the alleviation of these current problems.
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