Page 856 - Cardiac Nursing

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832 PA R T V / Health Promotion and Disease Prevention
pancreatitis and hepatosplenomegaly. Abdominal pain of un-
known origin also has been documented as a physical finding. DIETARY MANAGEMENT
This pain may be associated with ischemic bowel and is related to OF HYPERLIPIDEMIA
increased blood viscosity, macrophage ingestion of fat particles, or
the effect of the size of the lipid particles on abdominal tissue. 22 Evidence of the relationship between dietary intake, plasma cho-
Patients with chylomicronemia, or markedly elevated triglycerides lesterol, and CVD has been steadily accumulating. Seminal pop-
levels, have a high risk for pancreatitis.
ulation studies have shown that countries with the highest inci-
dence of CVD and elevatedblood cholesterollevels also have high
dietary intakes of saturatedfats. 76–79 Developing countries with a
LIPOPROTEIN MEASUREMENT mean cholesterollevelless than 150 mg/dL have a very low inci-
dence of CVD and also have diets low in totalfat, saturatedfatty
The measurement of plasma lipids and lipoproteins is essential for acids, and cholesterol. 77
the diagnosis of lipid abnormalities and for the identification of
those at risk for CVD. These measurements also provide impor- Diet Patterns and Lipid Effects
tant feedback to the patient modifying his or her risk profile. The
Epidemiology studies and randomized clinical trials have examined
most common lipid analysis includes measurement of total cho-
the relationship of dietary patterns including very-low fat, reduced
lesterol, total triglycerides, and HDL cholesterol. This allows cal-
saturatedfat, vegetarian diets, and the Mediterranean diet with car-
culation of LDL using the following equation: LDL total cho-
73
lesterol (triglycerides 5) HDL. This indirect assessment diovascular outcomes such as CVD events, mortality, or angio-
graphic disease progression. In general, a benefit was observed if the
of LDL can be used if triglycerides are less than 400 mg/dL. If 80
dietary pattern was followed. The goal of these low-fat dietary
triglycerides are more than 400 mg/dL, then LDL must be di-
patterns was to reduce LDL blood concentrations. However, more
rectly measured using the more complex and costly ultracentrifu-
recent studies oflow-fat dietary plans have noteddetrimental effects
gation procedure.
on other lipid parameters including reductions in HDL and in-
To interpret the results of lipid measurements, some knowl-
creases in triglyceride levels leading to a controversy about which
edge of the accuracy and precision of the measure is useful. One
diet is best for CVD. The effects ofdiet on lipidparameters relates
of the common scenarios encountered in lipid management is a
to the amount offat, the type offat, and whether fat is replaced
laboratory report with values extremely different from the pre- 81
withprotein or carbohydrate. Sacks and Katan have estimated the
viously measured values, and the patient protests, “I have not
lipid effects offour common dietary plans: the average Western diet
been doing anything differently.” Intraindividual cholesterol
(38% totalfat, 17% saturatedfat, 42% carbohydrates), a 30% to-
measurements have been shown to vary by 4% to 11% over a
1-year period. 74 Although there are several sources for variabil- talfat diet, a 20% totalfat diet, and the Mediterranean diet (a re-
duced saturatedfat diet with increased use of vegetable oils such as
ity or error in cholesterol measures, the most obvious is analytic
olive oil, and increased intake of vegetables, fruits, andfish). Com-
variability, or laboratory error, which has been estimated to
pared with the western diet, LDL is reducedby 6%, 12%, and 13%
contribute one third to one half of the intraindividual variabil-
in each of the above-mentioneddiet patterns, respectively. Con-
ity. Laboratories must make their standardization criteria avail-
versely, HDL is reducedby 9%, 20%, and 9% in eachdiet pattern,
able and should strive to achieve less than 3% measurement
respectively. The net result is that the cholesterol to HDL ratio in-
variability. Biologic and physiologic factors constitute the other
creases in bothlower fat diets but is lower with the Mediterranean
major source for measurement variability. To minimize meas- 81
diet. Saturated fatty acids, with the exception of stearic acid, raise
urement variability, the National Cholesterol Education Labo-
total and LDL cholesterol probably through a mechanism decreas-
ratory Standardization Panel recommends the following stan- 82
74
dards of practice : ing LDL receptor synthesis. Studies suggest that diets high in
monounsaturatedfat relative to saturatedfat provide a desirable
1. A stable lifestyle, including health status, diet, medication, and plasma lipid profile, withlowering of total and LDL cholesterol and
activity level, should be followed for at least 2 weeks before no reduction in HDL. 83 The major criticism of these studies has
measurement. been that the addition of only unsaturated fats to the diet is not
2. Cholesterol measures should be made no sooner than 8 weeks practical among free-living individuals. For example, food items
after MI, surgical procedure, trauma, or an acute bacterial or vi- high in stearic acid usually contain other highly saturatedfatty acids
s
ral infection. as well. Studies also have found that trans-fats (partially hydro-
s
3. In acute coronary syndrome, it is recommended that a lipid genated unsaturatedfats) raise LDL levels but show no effect on
profile be collected at the earliest possible time during hospi- HDL levels, resulting in an even higher cholesterol to HDL ratio. 82
talization. 75 The effect of other dietary additives on plasma lipids has also
4. Blood collection procedures should include a 12-hour fast been studied. Dietary studies on the effect of increased omega-3
(except for water and usual medications) before sampling if fatty acids either by fish intake or supplementation withfish oils
lipid measures other than total cholesterol are to be per- have shown an effect on plasma lipids, primarily triglyceride lower-
formed. ing with concomitant increases in HDL. 84,85 The response is dose
5. The patient should sit quietly for 5 minutes before the related and is sufficiently high that it is unlikely to be achieved us-
venipuncture. ing food choices only. Omega-3 fatty acids also exert antithrom-
6. The sample should be obtained within 1 minute of tourniquet botic effects through the thromboxane–prostaglandin pathways,
application. resulting in decreases in platelet aggregation and vasoconstriction.
7. Standardized procedures for processing and transporting sam- Although the safety of consumption oflarge amounts offish oils is
ples should be followed. an issue, most researchers agree that the inclusion offish several