Page 1617 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1136 PART 10: The Surgical Patient

with low molecular weight heparin (LMWH) or low-dose unfraction- selecting for antimicrobial resistant organisms is a major concern. Short-
ated heparin (LDUH) is recommended, once the bleeding risks diminish term use of ICP monitors does not appear to lead to increased morbid-
or the contraindication to heparin resolves. There are no evidence- ity and mortality; however, the use of routine ventriculostomy catheter
200
based data in TBI to determine what type of pharmacologic prophylaxis exchanges for the prevention of CSF infections is not recommended. 26
is superior or to support a recommendation regarding when it is safe Patients receiving prolonged prophylactic antibiotics do not have a
to begin pharmacological prophylaxis. Early initiation of LMWH reduced incidence of pneumonia and may be at greater risk of delayed
203
(enoxaparin) therapy 203,206 after TBI is associated with a higher incidence pneumonia with resistant or gram-negative bacteria. A major issue
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of bleeding complications and the earliest time to begin pharmacologic with ventilator-associated pneumonia (VAP) is that the definitions are
VTE prophylaxis after TBI is uncertain, although it should be avoided imprecise and noninfectious entities such as atelectasis infiltrate due to
perioperatively. A recent retrospective review of 287 moderate-to- mucus plugging and acute lung injury common after TBI may be incor-
203
severe TBI patients over a 5-year period VTE prophylaxis with enoxa- rectly attributed to VAP. 219
parin or dalteparin was instituted within 48 to 72 hours posttrauma, in
highly select group of patients with no confounding coagulopathy and
when two consecutive CT scans revealed hemorrhage stability, reported NUTRITION AND METABOLIC MANAGEMENT
only one patient with symptomatic expansion of IH while on VTE pro- As in critically ill patients in general, nutrition by the enteral route is
phylaxis, at 15 days posttrauma. However, randomized prospective preferred as early as is feasible after severe TBI. Current evidence sup-
207
studies will be needed to determine the safe timing of pharmacological ports the use of the enteral route with no clear benefit from additional
VTE prophylaxis after TBI. Currently, the best approach is to weigh total parenteral nutrition (TPN), unless the patient cannot tolerate
the risks and benefits of pharmacologic VTE in each TBI patient indi- enteral feeding. Although there is no strong evidence to support a
vidually, in consultation with the neurosurgeon, with the goal of starting particular optimal time to begin feeding after TBI, data show that unfed
pharmacologic prophylaxis as early as is safely possible. VTE prophy- TBI patients lose sufficient nitrogen to reduce weight by 15% per week.
220
laxis should be continued until patients are ambulatory. Since it usually takes several days to reach full caloric goals, 221,222 initiat-
The use of prophylactic inferior vena cava filters in patients with doc- ing nutritional support by at least 72 hours post-TBI is reasonable.
220
umented VTE and contraindications to anticoagulation is an accepted Patients who can be started on nutritional support on day 1 after TBI
practice; however, the use of IVC filters in patients with risk factors may have a higher percentage of energy and nitrogen requirements met
alone is controversial. 201,208,209 Many patients after TBI receive IVC filters by the end of the first week. 223
without an identifiable risk factor for VTE. After TBI, IVC filters Although enteral feeds have a lower cost, decrease GI bleeding from
209
should not be used for primary VTE prevention. 200 stress gastritis, and may improve gut integrity, occasionally the GI route
Routine venous compression ultrasound to periodically screen for is not available due to ileus, GI bleeding, or extracranial complications
DVT is not recommended after major trauma as the rate of false posi- of abdominal trauma and surgery. In this case, TPN has been found to
tives increases and there is no evidence that detection and treatment of be well tolerated after TBI and does not have adverse effects on ICP.
220
asymptomatic DVT reduces the risk of PE or fatal PE. 200 More recent data in general critically ill patients suggest that compared
to TPN initiation within 48 hours, beginning TPN at ICU day 8 or later
may be associated with faster recovery and fewer complications. 224
HEALTH CARE–ASSOCIATED INFECTIONS Metabolic studies of patients after TBI demonstrate nitrogen loss
Severe TBI patients are at risk for health care–associated infections and increased basal metabolic rates. The resting energy expenditure in
(HAI) common to the critically ill population including pneumonia, comatose TBI patients is elevated an average of 140% above expected
central venous catheter–related infection, acalculous cholecystitis, and and may be as high as 2.5 times predicted. 225,226 Paralytic agents, hypo-
Clostridium difficile colitis. HAI specific to TBI include CSF infection thermia, or barbiturate coma reduce the metabolic rate; however, even
due to ventriculostomy or other invasive brain monitors, and surgical after paralysis the energy expenditure may remain elevated by 20% to
227
site infections. HAI contribute to morbidity, mortality, and increased 30%. Negative nitrogen balance may occur despite increasing nitrogen
hospital length of stay. intake with less than 50% of administered nitrogen retained after TBI
Risk of infection after head trauma is greater in the presence of CSF and larger nitrogen loads lead to exaggerated nitrogen losses. 228
leaks, open fractures, paranasal sinus injury, transventricular injury, and Specific formulations of enteral and parenteral nutrition should be
to a lesser extent retained foreign bodies from penetrating trauma. based on the metabolic needs of the patient consistent with current criti-
210
After military penetrating head trauma, 11% develop abscesses, cereb- cal care practice. After estimating and supplying the projected caloric and
ritis, and meningitis. Gram-negative bacteria such as Klebsiella pneu- protein requirements, in patients that fail to respond and continue to lose
210
moniae are more common than Staphylococcus aureus. weight, measurement of nitrogen balance and assessment by indirect
Brain parenchymal ICP devices have a device tip culture infection calorimetry (metabolic cart) may be helpful to ensure the provision of
rate of 14%. The incidence of CSF infection after ventriculostomy is sufficient calories. The recommended amount of protein in enteral and
26
estimated at 5% to 10%, and can be as high as 27% ; it is treated by parenteral formulations is about 15% of the total calories in TBI patients. 220
26
211
removal of the device and antibiotics. The risk of external ventricular The preferred location (ie, gastric vs postpyloric) of feeding tubes
drainage (EVD) device infection may increase with the duration of is subject to debate and although some report better attainment of
monitoring, the presence of open skull fractures, intraventricular or nitrogen balance or caloric goals with postpyloric feeding or parenteral
229
220
subarachnoid blood, leakage around the EVD insertion site, flushing of nutrition, or lower rates of pneumonia with early enteral feeding
230
the EVD tubing, as well as the presence of coexisting systemic infection and transpyloric feeding, no superior method of feeding has been
and the use of prophylactic parenteral antibiotics. 26,212,213 clearly demonstrated after TBI. Studies of both gastric and jejunal feed-
Measures to reduce ventriculostomy infections include sterile prepa- ing have shown that full caloric requirements can be met in most TBI
ration, utilization of closed drainage systems, and minimizing flushing patients by 7 days post injury. 221,222,231 Continuous enteral feeding may be
and handling of the system. Bacitracin flushes via the ventriculostomy better tolerated than bolus feeding and able to achieve nutritional goals
232
to maintain lumen patency are associated with a higher infection rate. earlier. TPN is started at levels below resting metabolism expenditure
214
Antimicrobial-impregnated EVD catheters may significantly reduce and advanced to goal over 3 days or as tolerated.
determine the impact on infection. There are no data to support the ■ GLYCEMIC CONTROL
colonization rates but more studies in TBI patients are needed to
215
use of prophylactic antibiotics for the prevention of ventriculostomy Hyperglycemia in TBI patients has been associated with worse neu-
infection, 216,217 or any other infection in TBI patients, and the risk of rological outcomes in two class III human studies. 220,233,234 Whether

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