Plasma glutamine concentration after intensive care unit discharge: an observational study
Smedberg et al. Critical Care
Plasma glutamine concentration after intensive care unit discharge: an observational study
Marie Smedberg 0
Johanna Nordmark Grass 0
Linn Pettersson 0
ke Norberg 0
Olav Rooyackers 0
Jan Wernerman 0
0 Department of Anesthesiology and Intensive Care Medicine, K32, Karolinska University Hospital Huddinge , 141 86 Stockholm , Sweden
Introduction: Low plasma glutamine concentration at ICU admission is associated with unfavorable outcomes. The prediction of plasma glutamine concentration after ICU discharge on outcomes has not been characterized. In the recent Scandinavian Glutamine Trial, a survival advantage was seen with glutamine supplementation as long as patients stayed in the ICU. It was therefore hypothesized that the glutamine level may drop at ICU discharge, indicative of a sustained glutamine deficiency, which may be related to outcome. Methods: Fully fed ICU patients intravenously supplemented with glutamine for >3 days were studied at ICU discharge and post ICU. In study A, plasma glutamine level was followed every 5 to 7 days post ICU of the remaining hospital stay and compared to the level on the day of ICU discharge (n = 63). In study B, plasma glutamine level 24 to 72 hours after ICU discharge was related to 12-month all-cause mortality (n = 100). Results: Post-ICU plasma glutamine levels were within normal range and were not found to be predictive for mortality outcome. Plasma glutamine level at discharge, on the other hand, was within normal limits but higher in nonsurvivors. In addition, it was adding prediction value to discharge SOFA scores for post-ICU mortality. Conclusions: Post-ICU glutamine levels are not indicative of glutamine depletion. The relation between plasma glutamine concentration and glutamine availability during critical illness is not well understood, and needs to be studied further to define the possible role for glutamine supplementation.
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Introduction
A low plasma concentration of glutamine at intensive
care unit (ICU) admission is associated with an
unfavorable outcome [1,2]. A high glutamine concentration at
ICU admission may also communicate a negative
prediction [2]. Other reports claim that free glutamine
depletion in tissues (during ICU stays) is associated with
unfavorable outcome [3,4]. So the hypothesis - that at
least some critically ill patients may have a shortage of
free glutamine - seems to be valid. Conventional
products for enteral feeding of critically ill patients contain
the same amounts of glutamine as ordinary food, while
conventional products for parenteral feeding of these
patients do not contain any glutamine, related to stability
issues. Consequently, supplementation of glutamine was
suggested [5].
Literature on glutamine supplementation for critically
ill patients is extensive. Meta-analyses suggest a
beneficial effect when intravenous (iv) supplementation is
given to ICU patients on parenteral nutrition [6,7].
Reports on enteral supplementation to ICU patients on
enteral nutrition are less conclusive [6]. Only a few studies
include plasma glutamine concentration measurements
as a possible indicator of individuals with glutamine
depletion, which should be the proper target group for
supplementation [8-10]. The rational for supplementing
critically ill patients - without knowledge of their actual
glutamine status - has been that glutamine
supplementation was considered to be without side effects [5,11]. But
recently, a study demonstrated harm when supplying
glutamine in high doses as a part of a pharmaconutrition
concept in the acute phase of critical illness [9], although
the subjects were a selected subgroup that received
hypocaloric nutrition and had two or more organ
failures. So better knowledge of the glutamine status and
whether or not an actual deficiency of glutamine is
present in the individual patient is needed.
The Scandinavian Glutamine Trial indicated in
secondary outcomes of only patients treated per protocol
that iv glutamine supplementation may improve
outcome during ICU stay [12]. This possible benefit,
however, was not sustained after ICU discharge, which may
be related to that glutamine supplementation was
discontinued at discharge. To elucidate this hypothesis two
observational research studies were launched: Study A - to
follow plasma glutamine concentrations after ICU
discharge, and Study B - to find out if post-ICU plasma
glutamine concentration is a mortality predictor.
Methods
Patients
The unit has 12 beds and is the only ICU at the
Huddinge wing of Karolinska University Hospital, which
includes transplant surgery, major gastrointestinal
surgery, hematology and infectious diseases, but not cardiac
surgery, trauma care and neurosurgery. The protocol was
to include consecutive patients admitted to the general
ICU at Karolinska University Hospital Huddinge, who
received iv glutamine supplement for >3 days. Exclusion
criteria were: age <18, restrains of treatment, absence of
informed co (...truncated)