Early enteral nutrition in critically ill patients with a high-protein
diet
enriched with arginine, fiber, and antioxidants compared with a standard
high-protein diet. The effect on nosocomial infections and outcome.
Reference: JPEN 2001;25(6):299-308.
BACKGROUND: This study was designed to evaluate the effects of a high-protein
formula
enriched with arginine, fiber, and antioxidants compared with a standard
high-protein formula in
early enteral nutrition in critically ill patients. METHODS: For this study,
220 patients were
enrolled in a prospective, multicenter, single-blind, randomized trial
in 15 Spanish intensive care
units (ICUs). The primary end-points were the incidence density rates of
nosocomial infections,
ICU and hospital length of stay, ICU and in-hospital mortality, and mortality
at 6-month
follow-up. RESULTS: The patients in the control and study groups had similar
baseline
characteristics. The study group had a lower incidence of catheter-related
sepsis (0.4
episodes/1000 ICU days) than the control group (5.5 episodes/1000 ICU days),
with a relative
risk (RR) of 0.07 (95% confidence interval [CI] 0.01 to 0.54, p < .001).
There were no
differences in the incidence of ventilator-associated pneumonia, surgical
infection, bacteremia, or
urinary tract infections between the 2 groups. ICU mortality (16% in the
study group versus 21%
in the control group; RR 1.5, CI 95% 0.7 to 2.9) and in-hospital mortality
(21% in the study
group versus 30% in the control group; RR 1.6, CI 95% 0.9 to 3) were similar
without
differences in survival at 6-month follow-up (75% in the study group versus
68% in the control
group, p = .15). Patients in the study group who were treated for 2 or
more days showed a
strong trend for better survival at 6-month follow-up (76% in the study
group versus 67% in the
control group, p = .06). Medical patients treated with the study diet had
better survival than
medical patients in the control group (76% in the study group versus 59%
in the control group, p
< .05). CONCLUSIONS: Critically ill patients fed a high-protein diet
enriched with arginine,
fiber, and antioxidants had a significantly lower catheter-related sepsis
rate than patients fed a
standard high-protein diet. There were no differences in mortality or ICU
and hospital length of
stay. The subgroup of patients fed the study diet for >2 days showed a
trend toward decreased
mortality.
Postoperative
starvation after gastrointestinal surgery:Early feeding is beneficial
Reference: BMJ 2001;323:761-762.
The widespread practice of starving patients in
the immediate period after gastrointestinal surgery has been challenged
by a systematic review and meta-analysis in this issue (p 773), which finds
that "nil by mouth" after
gastrointestinal surgery may not be beneficial.1
Further, the apparently beneficial effects of early postoperative enteral
feeding on infection rates and length of stay in hospital are compelling
arguments in favour of a change in clinical practice.
The rationale of nil by mouth and gastric decompression
is to prevent postoperative nausea and vomiting and protect the anastomosis,
allowing it time to heal before being stressed by food. Nausea and vomiting,
however, occur more commonly after upper gastrointestinal surgery than
after resection of the small intestine and colon. In our clinical experience
nasogastric decompression can usually be discontinued 12-24 hours after
resection of the small intestine and colon.
There is no evidence that bowel rest and a period
of starvation are beneficial for healing of wounds and anastomotic integrity.
Indeed, the evidence is that luminal nutrition may enhance wound healing
and increase anastomotic strength, particularly in malnourished patients.
The findings of the meta-analysis, however, raise
some important questions. Should early postoperative feeding be restricted
to patients with pre-existing malnutrition; is its efficacy related to
the degree of surgical injury; and is the main site of action of luminal
nutrition the level of the intestinal barrier?
Pre-existing malnutrition has been shown to be
a major clinical problem in surgical patients. Although several factorsage,
coexisting disease, type and extent of surgical procedure, blood loss,
duration of procedure, skill of the surgeon, and the disease itselfhave
been shown to be associated with postoperative complications, nutritional
depletion is an independent determinant of serious complications after
major gastrointestinal surgery. Surgical injury itself increases resting
energy expenditure and protein loss, and intake of energy and protein after
gastrointestinal surgery fall well below what is required throughout the
stay in hospital. Understandably, the advocates of early postoperative
enteral feeding have therefore often focused on its use in malnourished
patients.
Pre-existing nutritional depletion, however, may
not be the only nutritional factor associated with postoperative complications
after gastrointestinal surgery. Two recent studies on postoperative enteral
feeding showed that nutritional support was associated with a significant
reduction in postoperative complications, a reduction that was independent
of preoperative nutritional status.
The benefits of postoperative enteral feeding
in normally nourished surgical patients indicate that it is reduced nutritional
intake that predisposes patients to developing complications, including
deficits in muscle function and surgical fatigue. There is thus no evidence
that early postoperative enteral feeding should be restricted to malnourished
patients undergoing gastrointestinal resection. Indeed, one study has found
that supplementing "normal" oral diet in hospital wards with as little
as 1250 kJ (300 kcal) and 12 g of protein per day resulted in a reduction
of postoperative complications in patients undergoing gastrointestinal
surgery. Therefore, there may be a threshold of nutritional intake which,
if not achieved, may predispose some patients to postoperative complications.
As the authors have pointed out, the randomised
trials they identified were heterogeneous as to underlying diagnosis and
type of surgery. Ten of 11 studies reported the site of surgery. Importantly,
in all but two studies most patients underwent lower gastrointestinal surgery.
In the two studies in which patients underwent major upper gastrointestinal
surgery, early postoperative enteral nutrition either afforded no advantages
over standard care or seemed to have a deleterious effect.
One explanation of these results might be that
the surgical injury is less and the metabolic response to it relatively
modest in patients undergoing lower gastrointestinal surgery, compared
with patients undergoing major upper gastrointestinal surgery. Only in
patients undergoing lower gastrointestinal surgery does enteral nutrition
in the early postoperative period have an important impact.
Recently, changes in intestinal permeability have
been shown in patients undergoing gastrointestinal surgery, increased permeability
being associated with sepsis and systemic inflammation. Bacterial translocation
has also been shown in patients undergoing laparotomy, and a higher proportion
of patients with bacterial translocation developed sepsis than those without.
There is, however, no evidence in humans that increased intestinal permeability
correlates with bacterial translocation or that early postoperative enteral
nutrition influences intestinal permeability or reduces the incidence of
bacterial translocation. The appealing hypothesis that early postoperative
luminal nutrition might have a beneficial effect on the function of the
intestinal barrier in respect of permeability, bacterial translocation,
and the subsequent development of septic complications has no supporting
evidence at present.
What impact could the findings of this systematic
review have on daily surgical practice? The review shows that there is
no clinical benefit to starving patients in the early postoperative period
after gastrointestinal resection. Further, the finding that postoperative
infections can be reduced and hospital stay shortened by starting early
postoperative enteral nutrition should challenge clinicians to consider
this treatment. The findings pave the way for an appropriate multicentred
trial to assess early enteral feeding in patients undergoing elective gastrointestinal
resection. The patients recruited to such a trial should be stratified
by nutritional status and type of surgical procedure. The outcome measures
should include not just effects on wound infection, other infectious complications,
and dehiscence of the anastomosis but also surgical fatigue, muscle function,
quality of life after
discharge from hospital, and cost effectiveness.
Protein
energy supplements in unwell elderly patients--a randomized controlled
trial
Reference: JPEN;2001;25(6):323-9.
BACKGROUND: To determine whether oral protein energy supplements, prescribed
during hospitalization to elderly medical admissions, affect nutritional
status and if baseline nutritional state influences this status. We also
considered the effects on mortality, length of hospital stay,functional
recovery, and institutionalization. METHODS: A prospective randomized controlled
trial with no placebo. Consenting patients were stratified in 3 nutritional
categories, and patients from each stratum were randomized into treatment
or control. Observers were blinded to randomization. The participants were
emergency admissions from home to a Medicine for the
Elderly Unit in a Scottish hospital. The inclusion criteria were as
follows: no known malignancy,the ability to swallow, and nonobesity (BMI
< 75th percentile). The intervention was a prescription of 120 mL sip
feed, 3 times daily (540 kcal, 22.5 g protein per day) throughout hospitalization,
using the medicine prescription chart. The trial was powered to detect
change in mean percentage weight. The following outcomes were also considered:
anthropometry; mortality, length of hospital stay, functional recovery,
and rates of institutionalization. RESULTS:Included in the trial were 381
patients. Nutritional supplementation was associated with significantly
better energy intake (p = .001) and weight gain (p = .003) pooled across
all nutritional categories. In the most poorly nourished patients, the
intervention was associated with reduced mortality (5/34 versus 14/40,
p < .05) and more patients improved functionally (17/25 versus 11/28,
p < .04). Overall mortality results were 21/186 versus 33/195, odds
ratio (OR) 0.62, 95% confidence interval (CI) 0.35, 1.13. CONCLUSIONS:
Prescribing sip feed supplements in the medicine prescription chart during
hospital stay reduces weight loss. Our data also support other evidence
for a reduction in mortality noted in elderly patients on nutritional supplementation.
There were suggestions of other clinical benefits.
Muscle function in critically ill patients.
Reference: Clin Nutr 2001;20(5):451-4.
Endotoxemia and inflammation (cytokines) lead to an acute decrease of the
muscle resting
membrane potential, loss of the sodium-potassium gradient and to an increase
in cytosolic
Ca(2+) in critically ill intensive care unit patients. As a consequence,
muscle (and nerve)
contractility is reduced. As a consequence also, amino acid gradients are
reduced, proteolysis is
increased, the mitochondrial density is reduced to levels as low as 10%
of normal within 2-3 days
and cellular substrate metabolism is impaired. The author of this paper
proposes that treatment
modalities in clinical nutrition should primarily aim at improving muscle
function and restoring
muscle membrane potential and that these variables should be used as the
primary outcome
variables of clinical trials. Attempts to modify these measurements such
that they can be used
routinely in the ICU setting are ongoing in our group. Muscle protein and
substrate metabolism
can only be normalized when these primary variables have successfully been
restored. The use of
muscle relaxants may lead to a functional denervation of the muscle, to
changes in the molecular
structure of the myofibrils and may postpone a successfull recovery. Learning
objectives: Causes
of muscle weakness and loss of contractility in ICU patients; Relation
between loss of
contractility and impairments in muscle metabolism; Muscle function as
an endpoint variable for
clinical nutrition interventions.
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