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Chapter 8
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Prevention of PN-related complications
By withholding PN, complications associated with central venous access
45
and composition of
PNsolutions
46
mightbeprevented. Despite theseadditional complicationsof PNadministration,
only 3.5% of PICUs would withhold PN for at least 7 days (Chapter 2). Also, after the first week
of PICU stay, a large proportion (38%) of the PEPaNIC children depended on PN with its added
risk. The complications associated with central venous access devices are not likely to have
contributed to the beneficial effects of late PN, since the percentage of central venous lines is
expected to be similar between the two treatment groups. Moreover, the reduced proportion
of patients with a new infection in the late PN group was not only attributable to fewer patients
acquiring a blood stream infection, but also to fewer airway infections. Clinical implementation
of the late PN strategy will most likely decrease the number of venous access devices and
associated complications in the future, although venous access remains essential for different
reasons than provision of PN in the large proportion of children with multi-organ failure and/
or underlying chronic diseases.
Use of PN has also been identified as a risk factor for caloric overfeeding
47,48
. Furthermore,
patients with the lowest cumulative caloric intake (lowest dose intervals) showed a similar
or better outcome than any of the higher doses in post-hoc analyses of adult RCTs
19,49
. By
reducing the total caloric intake with late initiation of PN (Chapter 7), the prevalence of caloric
overfeeding and its complications are likely to decrease. However, it is difficult to investigate
the prevalence of overfeeding and its contribution to the unfavourable outcome in the early
PN group. Endogenous glucose production is presumed to match 50-75% of REE the first days
after admission
50
, resulting in an uncertainty of actual energy requirements when endogenous
sources are used for energy. Current definitions of overfeeding are considered inadequate
because they fail to take this and several other essential patient and disease related factors into
account, and even identify patients with an intake below the threshold to equilibrate nitrogen
balance as overfed (Chapter 4).
On the other hand, one might state that recommendations by current guidelines reflect
overfeeding in the acute phase of critical illness, because providing early PN in agreement
with these guidelines is clinically inferior to withholding PN during this phase.
In summary, despite the lack of adequate definitions, macronutrient intake should be
reduced during the acute phase, since introduction of (supplemental) PN will easily result in
overfeeding
51
(Chapter 1).
The role of macronutrient dose
Strategies of early and late initiation of PN differed in parenteral macronutrient intake, with no
provision of amino acids and lipids and reduced intake of glucose in the late PN group (Chapter
6). High parenteral intake of glucose and amino acids are known to cause multiple, mostly
metabolic, side effects in children
23,52-59
.