Watchman
Sun, Apr-28-02, 01:01
I am hoping someone might take the time to answer this
question ..
For that little kid over there ..
In studying I ran across this snip from a IV feeding site and
came across what I thought to be an interesting point.
I believe it states .. high lipids lead to inflammatory
condition ..?
Because of this low rate of blood flow, the venous
epithelium of the superficial veins is highly susceptible
to injury from hyperosmolar infusions. The net result is
local inflammation that further reduces blood flow and
accentuates the injury response, inducing phlebitis.
For example, the clinical course of adult respiratory
distress syndrome (ARDS) can worsen with the
administration of large quantities of lipid emulsion.(14)
For these reasons, acutely ill patients with moderate to
severe metabolic stress usually cannot be fed entirely by
PPN therapy.
Subject: rate of blood flow/microvessels
Because of the relatively low rates of blood flow through
the peripheral veins, the ability of smaller blood vessels
to withstand concentrated parenteral nutrition admixtures
is severely limited. Hemodilution plays an important role
in the lifespan of indwelling intravascular catheters
principally, but not exclusively, by reducing osmotic
injury to the vein intima. Unlike the large central veins
used for TPN therapy, where blood flow approaches 2500
mL/min, flow through the superficial veins is approximately
25 to 50 mL/min.
Because of this low rate of blood flow, the venous
epithelium of the superficial veins is highly susceptible
to injury from hyperosmolar infusions. The net result is
local inflammation that further reduces blood flow and
accentuates the injury response, inducing phlebitis. The
osmolarity of the final admixture is a major factor in the
development of peripheral vein phlebitis. To reduce the
incidence of phlebitis from osmotic injury, PPN admixtures
are formulated so that the final osmolarity is maintained
at or below 900 mOsm/L.
Concentrations above this level dramatically increase the
risk of phlebitis.(9,10) When the concentration exceeds
900mOsm/L, the ability of the peripheral veins to dilute
parenteral infusions sufficiently is compromised, and
chemical irritation of the vein intima occurs. Admixtures
greater than 600 to 900 mOsm/L are associated with
increased rates of phlebitis.(9,10) Likewise,
concentrations of potassium chloride exceeding 40 mEq/L(10)
and acidic infusions(11,12) are additional risk factors for
phlebitis. Finally, for similar reasons, patients with
circulatory abnormalities (e.g., diabetes mellitus) may
have poor venous access or may not tolerate peripheral vein
infusions. Candidates for PPN therapy should be evaluated
by an experienced clinician to ensure that sufficient
peripheral vein access is available for the projected
course of therapy.
Clinical Considerations
Because of the limited ability of the peripheral veins to
tolerate concentrated nutritional admixtures, large volumes
of fluid are necessary if the patient's nutritional needs
are to be met solely by PPN therapy. Table 8-1 identifies
diluted PPN admixtures that maintain an osmolarity at 900
mOsm/L or less. Although this level may be achieved in
patients with good cardiopulmonary and renal function, it
may not be possible in many hospitalized patients with
limited organ function. Volume overload is common in the
critical care setting and may complicate the management of
these patients.(13) Similarly, disorders that cause fluid
retention (e.g., congestive heart failure, liver disease,
renal failure) may pose additional clinical concerns. For
these reasons, PPN therapy is not indicated as the primary
source of nutrition support in these patients.
Lipid emulsions are a dense caloric source. They are
essentially isosmotic with blood and can be substituted for
a portion of the glucose calories to permit the patient's
total energy needs to be met with PPN therapy. Lipid
emulsions can reduce the fluid burden in these patients
when these components account for 60% or more of the total
caloric intake. Again, the management of certain clinical
conditions
(i.e., hyperlipidemias, particularly hypertriglyceridemia;
sepsis; liver disease) may be affected by high
concentrations of exogenous lipids. Moreover, because
linoleic acid is a precursor to the vasoactive
prostaglandins, additional complications may ensue.
For example, the clinical course of adult respiratory
distress syndrome (ARDS) can worsen with the
administration of large quantities of lipid
emulsion.(14) For these reasons, acutely ill patients
with moderate to severe metabolic stress usually
cannot be fed entirely by PPN therapy.
--
Jesus was a Vegetarian! http://www.nucleus.com/watchman Moses
was a Mystic! http://www.nucleus.com/watchman/light.html
question ..
For that little kid over there ..
In studying I ran across this snip from a IV feeding site and
came across what I thought to be an interesting point.
I believe it states .. high lipids lead to inflammatory
condition ..?
Because of this low rate of blood flow, the venous
epithelium of the superficial veins is highly susceptible
to injury from hyperosmolar infusions. The net result is
local inflammation that further reduces blood flow and
accentuates the injury response, inducing phlebitis.
For example, the clinical course of adult respiratory
distress syndrome (ARDS) can worsen with the
administration of large quantities of lipid emulsion.(14)
For these reasons, acutely ill patients with moderate to
severe metabolic stress usually cannot be fed entirely by
PPN therapy.
Subject: rate of blood flow/microvessels
Because of the relatively low rates of blood flow through
the peripheral veins, the ability of smaller blood vessels
to withstand concentrated parenteral nutrition admixtures
is severely limited. Hemodilution plays an important role
in the lifespan of indwelling intravascular catheters
principally, but not exclusively, by reducing osmotic
injury to the vein intima. Unlike the large central veins
used for TPN therapy, where blood flow approaches 2500
mL/min, flow through the superficial veins is approximately
25 to 50 mL/min.
Because of this low rate of blood flow, the venous
epithelium of the superficial veins is highly susceptible
to injury from hyperosmolar infusions. The net result is
local inflammation that further reduces blood flow and
accentuates the injury response, inducing phlebitis. The
osmolarity of the final admixture is a major factor in the
development of peripheral vein phlebitis. To reduce the
incidence of phlebitis from osmotic injury, PPN admixtures
are formulated so that the final osmolarity is maintained
at or below 900 mOsm/L.
Concentrations above this level dramatically increase the
risk of phlebitis.(9,10) When the concentration exceeds
900mOsm/L, the ability of the peripheral veins to dilute
parenteral infusions sufficiently is compromised, and
chemical irritation of the vein intima occurs. Admixtures
greater than 600 to 900 mOsm/L are associated with
increased rates of phlebitis.(9,10) Likewise,
concentrations of potassium chloride exceeding 40 mEq/L(10)
and acidic infusions(11,12) are additional risk factors for
phlebitis. Finally, for similar reasons, patients with
circulatory abnormalities (e.g., diabetes mellitus) may
have poor venous access or may not tolerate peripheral vein
infusions. Candidates for PPN therapy should be evaluated
by an experienced clinician to ensure that sufficient
peripheral vein access is available for the projected
course of therapy.
Clinical Considerations
Because of the limited ability of the peripheral veins to
tolerate concentrated nutritional admixtures, large volumes
of fluid are necessary if the patient's nutritional needs
are to be met solely by PPN therapy. Table 8-1 identifies
diluted PPN admixtures that maintain an osmolarity at 900
mOsm/L or less. Although this level may be achieved in
patients with good cardiopulmonary and renal function, it
may not be possible in many hospitalized patients with
limited organ function. Volume overload is common in the
critical care setting and may complicate the management of
these patients.(13) Similarly, disorders that cause fluid
retention (e.g., congestive heart failure, liver disease,
renal failure) may pose additional clinical concerns. For
these reasons, PPN therapy is not indicated as the primary
source of nutrition support in these patients.
Lipid emulsions are a dense caloric source. They are
essentially isosmotic with blood and can be substituted for
a portion of the glucose calories to permit the patient's
total energy needs to be met with PPN therapy. Lipid
emulsions can reduce the fluid burden in these patients
when these components account for 60% or more of the total
caloric intake. Again, the management of certain clinical
conditions
(i.e., hyperlipidemias, particularly hypertriglyceridemia;
sepsis; liver disease) may be affected by high
concentrations of exogenous lipids. Moreover, because
linoleic acid is a precursor to the vasoactive
prostaglandins, additional complications may ensue.
For example, the clinical course of adult respiratory
distress syndrome (ARDS) can worsen with the
administration of large quantities of lipid
emulsion.(14) For these reasons, acutely ill patients
with moderate to severe metabolic stress usually
cannot be fed entirely by PPN therapy.
--
Jesus was a Vegetarian! http://www.nucleus.com/watchman Moses
was a Mystic! http://www.nucleus.com/watchman/light.html