Eur J Trauma Emerg Surg (2017) 43:775–782
The impact of measurement of respiratory quotient by indirect
calorimetry on the achievement of nitrogen balance in patients
with severe traumatic brain injury
· C. Gwardschaladse
· G. Lombardo
· P. Petrone
· A. Policastro
· K. Prabhakaran
· A. Betancourt
· C. P. Marini
Received: 16 February 2016 / Accepted: 10 September 2016 / Published online: 22 September 2016
© Springer-Verlag Berlin Heidelberg 2016
decreases protein utilization and optimizes the achievement
of +NB by day 7.
Keywords Indirect calorimetry · Nitrogen balance ·
Respiratory quotient · Severe traumatic brain injury
Severe traumatic brain injury (sTBI) remains a signiﬁcant
public health issue. There are 1.4 million cases of TBI
annually in the United States resulting in 270,000 hospitali-
zations and 52,000 deaths each year, with approximately
85 % of deaths occurring within the ﬁrst 2 weeks of the
injury [1, 2]. The consequences and burden of the care of
TBI patients present speciﬁc challenges to the health care
system making TBI one of the most disabling injuries with
an associated cost greater than 100 billion dollars each
year. Currently, the management of patients with sTBI is
centered on the prevention of secondary brain injury by
preventing the occurrence of hypoxia and hypotension
and by maintaining an adequate cerebral perfusion pres-
sure (CPP) with the optimization of the mean arterial blood
pressure and the intracranial pressure (ICP) .
Patients with sTBI are hypermetabolic and remain cata-
bolic even when given an adequate number of calories/
kg and protein adjusted to their increased metabolic rate.
Severe TBI triggers hypermetabolism and catabolism
severely impairing nitrogen retention. The hypermetabo-
lism is the result of a disproportionately higher pro-inﬂam-
matory cytokine production (e.g., tumor necrosis factor-α,
interleukin-1 and interleukin-6) that is associated with
increased production and release of counter-regulatory
hormones, such as cortisol, glucagon, and catecholamines.
This process causes increased systemic and cerebral energy
Background This study evaluated the impact of IC on the
optimization of nutritional support and the achievement of
+NB in patients with TBI.
Materials and methods 27 patients (GCS ≤ 8), treated
with a 5-day multimodality monitoring and goal-directed
therapy protocol, received enteral nutrition on day 1 fol-
lowed by IC on days 3 and 5 and assessment of NB on day
7. In the ﬁrst cohort (n = 11), no adjustment in kcal was
made. In the second cohort (n = 16), nutrition was targeted
to an RQ of 0.83 by day 3. The ﬁrst cohort was analyzed
with respect to NB status; the second cohort was compared
to patients with (−) and +NB of the ﬁrst cohort. Data
(mean ± SD) were analyzed with unpaired t test, and Chi
square and Fisher exact tests.
Results 4/11(36 %) patients in the ﬁrst cohort had +NB.
The predicted mortality by TRISS, substrate utilization, and
RQ was signiﬁcantly lower compared to the second cohort.
The mortality predicted by the CrasH model did not differ
between the two cohorts. A RQ of 0.74 was associated with
the preferential use of fat and protein and −NB, whereas a
RQ of 0.84 favored utilization of carbohydrates and +NB.
All patients whose kcal intake was adjusted based on the
RQ on day 3 reached a +NB by day 7.
Conclusion An increase in kcal ≥25 % in patients with
a RQ < 0.83 on day 3 improves substrate utilization,
* C. P. Marini
Division of Trauma Surgery, Surgical Critical Care and Acute
Care Surgery, Department of Surgery New York Medical
College, Joel A. Halpern Trauma Center, Westchester
Medical Center University Hospital, 100 Woods Rd Taylor
Pavilion E 138, Valhalla, New York 10595, USA