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32
J.A. Maykel
invasive feeding 5–7 days, or even more conservatively 7–10
days, after a period of fasting (if oral intake has not resumed)
is a reasonable and well-accepted guideline. These principles
refl ect evidence that up to 10 days of routine fl uid and electrolyte therapy can be tolerated without clinical harm in this
circumstance [ 16 ]. Those with a poor premorbid nutritional
status (i.e., more than 10 % weight loss or BMI less than
18 kg/m
2
) and superimposed illness are not as able to mount
an adequate infl ammatory response, which primarily impairs
wound healing and immune function. This nutritionally
related impairment of protein synthetic capacity increases
susceptibility to infectious complications and organ failure.
It is therefore important not to delay nutritional therapy and
to intervene within the fi rst several days. Although it has
been shown to be more effective to feed moderately malnourished individuals for 7 days prior to an elective major
operative procedure [
17 ], present day reality is that preopera-
tive or early post-injury feeding is generally not the rule.
This practice needs to be reconsidered. For those with the
most severe injuries which increase resting energy expenditure by 50 % or more, such as multiple trauma, major burns,
closed head injury, and severe sepsis, all of which commonly
result in lean tissue losses of 600–900 g/day without feeding,
early feeding is essential. In this group of patients, even in
the absence of pre-illness weight loss (rarely encountered by
the colorectal surgeon), adjuvant nutritional therapy should
be started soon after the acute resuscitation and metabolic
issues are resolved. In this setting, early feeding may diminish the intensity of the systemic infl ammatory response [
18 ,
19 ], which could be an important factor in improved clinical
outcome. Those patients who fall in between these extremes
are the most challenging with regard to delivery choice and
timing, and hopefully this chapter will better arm the reader
regarding the role and benefi ts of nutritional support.
Nutritional Options: Enteral and Parenteral
Key Concept : Nutritional supplementation has a storied history that encompasses several unique attempts to help
patients improve their status .
The goals of nutritional provision should be to provide
adequate protein (at least 1 g/kg/day and optimally 1.5 g/kg/
day) and energy (at least 1,000 kcal/day and optimally
25 kcal/kg/day) along with all essential nutrients, so as to
allow optimal protein synthesis for the support of the immune
system, wound healing, and vital organ function. Fortunately,
there are two available options, enteral and parenteral nutrition, to reach these goals in essentially all patients.
The administration of supplemental enteral nutrition dates
back hundreds of years. The ancient Egyptians provided support with enemas of wine, milk, whey, wheat, and barley. In
1790, Hunter created an orogastric tube made of a whale-
bone probe covered with eel skin attached to a bladder pump.
After an assassination attempt in 1881, President Garfi eld
was kept alive for 79 days with every 4-h rectal infusions of
peptonized beef, broth, and whiskey. Furthermore, in 1918,
Anderson placed the fi rst nasojejunal feeding tube.
The ability to provide intravenous nutrition support came
from revolutionary work done at the University of
Pennsylvania in the 1960s. In 1962, Rhoads began infusing
high volume peripheral solutions followed by diuretics. In
1966, Dudrick, Vars, and Rhoads documented their ability to
support normal growth and development of beagle puppies
with TPN. Finally in 1968, Dudrick and Wilmore demonstrated that they were able to safely support growth and
development of infant fed entirely by TPN. This milestone
revolutionized the nutritional support of surgical patients
and has had a transformational impact on perioperative morbidity and mortality that continues to this day.
Enteral Feeding
Key Concept : Although the dictum “ Whenever possible , feed
the gut ” is likely accurate , there is very little data in human
studies to back up its superiority over the parenteral route .
It is commonly stated that the administration of enteral
nutrition is “more physiologic” and its absence results in gut
mucosal atrophy and increased intestinal permeability, predisposing to bacterial translocation and increased rates of
septic complications [ 20 ]. Experimental evidence confi rms
that mucosal atrophy occurs with short-term bowel rest in
animals [ 21 ], but human studies to date do not support these
fi ndings. Remaining NPO over a short time course (up to 1
month) has no substantial effect on mucosal architecture
[ 22 ], while chronic starvation and malnutrition in humans do
result in changes in villous architecture [ 23 ].
Several investigators have looked at the potential clinical
benefi ts attributable to enteral feeding. There exists a large
cohort of animal studies showing that functional stimulation
of the GI tract resulting in the release of hormonal, biliary,
and pancreatic secretions prevents mucosal atrophy [ 24 ].
Enteral nutrients also improve intestinal blood fl ow, increase
the systemic and local immune response, increase the secretion of IgA, and increase the production of trophic hormones.
Although these fi ndings become considerably more vague
when humans are studied and clinical outcomes are evaluated, there is strong suggestive evidence for benefi t of early
feeding, particularly enteral, in the most critically ill [ 18 , 19 ].
In 1997, Reynolds et al. sought to answer the question if
early enteral feeding after major upper GI surgery modulates
gut barrier function and decreases the risk of major infectious complications compared with bowel rest and parenteral
nutrition [ 25 ]. According to previous studies, TPN had been
associated with an exaggerated acute phase and metabolic
3 Perioperative Nutrition Support in Colorectal Surgery
33
response after injury or endotoxin challenge, a response that
could be attenuated by enteral nutrition [
tors prospectively randomized 67 surgical patients to either 7
days of TPN or enteral feeding via operative jejunostomy
tubes. They showed that there was no clinical benefi t attributable to the enteral route of nutrient administration when
compared to the parenteral route. Furthermore, intestinal
permeability was equally increased postoperatively in both
groups (measured by lactose-mannitol ratios and serum antiendotoxin core antibodies), but the degree was not infl uenced by the provision of enteral or parenteral nutrition. In
addition, the magnitude of surgery-induced changes in the
acute phase reactants, albumin and C-reactive protein, were
not different between groups. Their results revealed that
major surgery does profoundly infl uence gut barrier function, but there was no evidence that enteral nutrition modulated gut barrier function or that septic morbidity was altered.
26 ]. The investiga-
Early Enteral Feeding Versus NPO
Key Concept : Early enteral feeding is likely not harmful ,
though has questionable evidence - based benefi t compared to
NPO for otherwise healthy patients undergoing surgery .
Some data exists citing improved outcomes to early enteral
feeding in the critically ill .
If there does not appear to be a signifi cant difference in
the stress response and clinical outcome between enterally
and parenterally fed patients, then is there a difference
between patients fed enterally and those fed not at all? This
question was studied in an extremely convincing article conducted by Heslin et al. from the Memorial Sloan-Kettering
Cancer Center [ 16 ]. The authors prospectively randomized
195 patients undergoing surgery for major upper gastrointestinal cancer. The enterally fed group was administered an
immune-enhancing diet via a jejunostomy tube, begun on
POD #1 and advanced to a goal of 25 kcal/kg. The control
group was administered intravenous crystalloid solutions. It
is important to note that the patients studied in this trial were
not malnourished, with mean preoperative weight loss of
only 6 % and initial serum albumin concentration of 4.0 g/
dL. The results revealed no signifi cant differences in postoperative complications, hospital stay, or mortality. The authors
concluded that there is no benefi t to early enteral feeding in
postoperative general surgical patients who are not malnourished at baseline.
A meta-analysis [ 27 ] looked at the 11 prospective ran-
domized controlled trials comparing the practice of early
enteral feeding to maintaining patients NPO after elective
gastrointestinal surgery . Their analysis of 837 patients concluded that (1) there is no clear advantage to keeping patients
NPO after elective GI surgery and (2) early feeding may be
of benefi t in decreasing infections and shortening postopera-
tive length of stay. A closer evaluation of their pooled data
revealed that the mean length of hospital stay was only
reduced by 0.84 days. Although there was an increase in
“any type of infection,” when considered individually, there
was no difference in the incidence of anastomotic dehiscence, wound infections, pneumonia, intra-abdominal
abscess, or mortality. Today early enteral feeding is a key
component to enhanced recovery after surgery (ERAS) programs routinely used following colon resection surgery.
In 2001, Marik and Zaloga performed another metaanalysis, this time looking at the 15 randomized controlled
trials that compared early with delayed enteral nutrition in
critically ill surgical patients [
were analyzed: early enteral nutrition was associated with a
signifi cantly lower incidence of infections (RR reduction
0.45) and reduced length of hospital stay (2.2 days). There
were no differences in noninfectious complications or mortality. The authors concluded that their pooled data supports
the practice of early initiation of enteral feeding but that their
conclusion should be interpreted with caution because of the
heterogeneity between studies.
In summary, it has been suffi ciently demonstrated that the
provision of nutrients is important to both support the
immune system and heal surgical wounds. Investigators
have further studied the route, timing, and metabolic response
of nutritional support. Reasonable conclusions based on the
studies quoted above would be that:
1. There is no benefi t from the immediate administration of
enteral nutrition to patients who undergo routine general
surgical procedures but are well nourished at baseline.
2. When patients are either malnourished or in the post-
injury stressed state, there is no obvious harm (and there
may be a clinical benefi t) to the initiation of immediate
enteral feeding, particularly in the more critically ill
patient.
3. The specifi c clinical benefi ts of a more aggressive
approach have yet to be confi rmed and will likely require
better powered future studies which focus on particular
subsets of patients.
28 ]. A total of 753 patients
Enteral Shortcomings
Key Concept : The benefi t of enteral feeding may be hindered
by an inability to tolerate feeds with either a nasojejunal or
nasogastric route .
While there appears to be support in the literature for
early enteral nutrition, most especially with immuneenhancing formulas, the majority of studies are handicapped
by the high prevalence of gastrointestinal intolerance leading
to inadequate tube feed administration. In fact, several studies have shown that patients who rely on enteral feeding
alone are underfed. In 1995, Heyland et al. enrolled 99 con-
34
J.A. Maykel
secutive ICU patients and recorded the initiating time and
tolerance of tube feeds [
29 ]. They found that approximately
one half of critically ill, hypermetabolic ICU patients were
intolerant of enteral feeding due to gastrointestinal dysfunction. Subsequently, in 2001, De Jonghe followed 51 consecutive ICU patients for the fi rst 14 days of nutritional delivery
[ 30 ]. The investigators discovered inadequate routine deliv-
ery of enteral nutrition, with more than half of the study
patients receiving <70 % of their nutritional goals. On further inspection, the etiology was multifactorial, equally distributed among the following: digestive intolerance (high
gastric residual >200 cc, constipation, diarrhea, abdominal
distention, vomiting, and regurgitation), airway management
issues, and discontinuation for diagnostic procedures.
To address this well-defi ned problem of enteral feeding
intolerance and resultant inadequate nutrition delivery, multiple studies have been performed to evaluate whether a
potential change in clinical practice may improve outcome.
When providing enteral nutrition, the decision to feed into
the stomach or into the small bowel has been both a point of
debate and of substantial clinical investigation. One approach
has been to determine if there is a noticeable clinical difference when delivering enteral formulas into the stomach, into
the duodenum, or into the jejunum. When discussing “transpyloric” or “postpyloric” feeding, most investigators distinguish between delivering nutrients (1) into some portion of
the duodenum or (2) beyond the ligament of Treitz, into the
proximal jejunum. The hypothesis has been that in bypassing
the region of potential gastroduodenal dysmotility, nutrients
directly infused into the jejunum would improve tolerance
while decreasing the potential for feeding complications
such as aspiration (Fig. 3.1 ).
Fig. 3.1 Postpyloric positioning of nasoenteric feeding tube
stalsis but does not result in an increase in actual aspiration
or in clinically defi nable pneumonia.
Feeding Tolerance
Aspiration
When investigators have prospectively compared nasogastric
to nasoduodenal feeding in principally medical ICU patients,
there has been no evidence for decreased rates of aspiration
[ 31 ] or of aspiration pneumonia [ 32 – 34 ]. Similar fi ndings
have been noted when comparing nasogastric to nasojejunal
feeding [ 35 – 37 ]. This is likely due to the lower esophageal
sphincter being stented open by any tube, regardless of where
its tip is positioned.
Esparza et al conducted a trial in 2001 which randomized
54 ICU patients to either gastric or transpyloric feeding [ 31 ].
All feeds were tagged with technetium 99m-radiolabeled
sulfur colloid, and the pulmonary secretions or lungs were
scanned on a daily basis to determine whether aspiration had
occurred. There was a nonsignifi cant difference in aspiration
between the gastric and transpylorically fed patients (7 % vs.
13 %). These fi ndings suggest that regurgitation of postpylorically delivered feeds exists secondary to retrograde peri-
Key Concept : Nasogastric and nasojejunal routes have simi-
lar rates of feeding tolerance .
The medications that have been employed as prokinetic
agents include antidopaminergic agents (i.e., metoclopramide), serotonergic agents (i.e., cisapride), and motilin
receptor agonists (i.e., erythromycin). While there is some
support for a role in the setting of gastroparesis, these agents
have been proven useless in impacting the degree or duration
small bowel or colonic ileus [ 38 ]. In addition to lack of effi -
cacy, administration of many of these agents results in unacceptable side effects. Cisapride is no longer available due to
cardiac arrhythmias and risk of sudden death. The practicing
surgeon commonly adds such agents with a hope of stimulating GI functional recovery, often understanding the lack of
benefi t while under recognizing the potential risks. These
agents should not be used at present, as we await new formulations with more reliable and predictable results. Alvimopan
is a peripheral μ antagonist that may prophylactically prevent postoperative ileus but must be initiated prior to narcotic administration.
3 Perioperative Nutrition Support in Colorectal Surgery
35
Regarding the issue of feeding tolerance, several studies
do reveal signifi cantly greater nutrient delivery when feeding beyond the pylorus [
35 – 37 ]. This difference appears to be primarily related to the
32 , 34 ] while others do not [ 33 ,
practice of holding feeds for high gastric residuals, the most
frequent gastrointestinal complication associated with
enteral feeding leading to decreased nutritional intake [
39 ].
When a more aggressive feeding protocol is followed, nasogastrically fed patients, despite having higher gastric residual volumes, receive equivalent amounts of enteral nutrition
to those fed nasojejunally [ 35 ].
One of the earliest studies that evaluated the potential difference between intragastric and jejunal feedings was performed in 1992 by Montecalvo et al. [ 40 ]. They prospectively
randomized 38 ICU patients to receive feeds through either
gastric or endoscopically placed jejunal tubes. Those patients
fed by the jejunal route received a signifi cantly higher proportion of their goal caloric intake (46.9 % vs. 61 %, p < .05)
but had equal rates of pneumonia (0 % vs. 10 %, p = NS).
In 2002, Davies et al. performed a prospective, randomized trial to evaluate the potential benefi ts of nasojejunal
(NJ) feeding compared to nasogastric (NG) feeding [ 35 ]. By
feeding directly into the jejunum, the authors hypothesized
that the patients would be more tolerant of enteral nutrition.
The study distinguished between criteria for “ceasing” tube
feeds and criteria for declaring a patient “intolerant” of feeds.
Instead of using the traditional cutoff range for high gastric
residual volumes (150–200 cc), the authors continued feeds
until a residual measured >250 cc beyond the previous residual measurement. They also commenced feeds at a rate of
20 cc/h and aggressively advanced by 20 cc every 4 h.
Patients were only declared “intolerant” when, over a 48-h
period, (1) feeds were stopped four times due to one of their
predefi ned complications or (2) a total gastric residual volumes of 2,000 cc was reached. By these criteria, 4/31 patients
in the NJ group were intolerant, although all 31 were eventually tolerant of enteral feeds after a holding period. A total of
11/35 patients in the NG group were intolerant. Of the 11
who were intolerant, 10 were eventually tolerant, either by
NG or NJ feeding. Only 1 patient went on to TPN.
Although the authors did demonstrate a signifi cant difference in gastric residual volumes (incidence 32 % vs. 74 %),
there was no difference in feeding tolerance. Once feeding
was initiated, there was no difference between the groups
with regard to the volume delivered at 24 and 48 h or the
time to reach target rate. Also, there were no differences in
clinical complications such as bleeding, pneumonia, sepsis,
SIRS, or mortality. It should be noted that there was a 1-day
delay in initiating enteral feeding in the NJ group. This was
directly attributable to a scheduling delay required to arrange
endoscopy by the gastroenterologist for tube placement. The
endoscopic placement of jejunal tubes does appear to be
technically feasible (98 % success rate) and safe but is the
effort and expense worth the trouble? As the enteral feeding
tubes were inadvertently removed in approximately onethird of the patients, tube dislodgment remains a major problem and is likely a major factor in reaching goal nutrition.
NG tubes can be replaced at the bedside, but NJ tubes
replacement typically requires repeat endoscopy or radiologic assistance.
Although NJ feeding results in reduced gastric residual
volumes, this feeding method does not consistently improve
feeding tolerance. It can be helpful in certain subsets of
patients, suggesting that NJ feeding can be an alternative to
TPN in the patient proven or likely to be intolerant to NG
feeding. This is an important fi nding. Its applicability to populations with higher likelihood of gastrointestinal intolerance such as postoperative patients or those with severe
pancreatitis or closed head injury will require further study
before implementation as a standard for all patients.
Enteral Complications
Key Concept : Though perhaps not as well publicized , enteral
feeding has its own unique set of potential complications
surgeons should be aware of .
One of the arguments used in support of enteral over parenteral feeding revolves around the morbidity associated
with central venous line placement and maintenance. In fact,
enteral feeding practices can often lead to unique adverse
effects of their own such as high gastric residuals leading to
refl ux, emesis and aspiration, abdominal distention, diarrhea,
constipation, and rarely mesenteric ischemia. Mechanical
complications include misplacement (endobronchial, intrapulmonary, and transesophageal), dislodgement, or malfunction from luminal blockage. Finally, enteral feeding
(particularly of ICU patients) is regularly discontinued for
both diagnostic and interventional procedures, often resulting in patient underfeeding (Fig. 3.2 ).
The above complications become particularly important
when one attempts to bypass the physiologic brake of gastroduodenal dysmotility by placing a postpyloric feeding tube.
There is a very small but substantial risk of mesenteric ischemia associated with jejunal feeding (estimated at 1 in
1,359), which is most likely to occur in patients showing
signs of abdominal pain, distention, increased NG drainage,
or intestinal ileus [ 41 ]. Given this uncommon but serious
potential complication with NJ feeding, protocols to avoid
high-risk patients such as hypotensive patients receiving
pressor agents or those with signifi cant abdominal pain seem
appropriate, since its low incidence renders this complication outside the ability to study clinically. Fortunately,
feeding- related small bowel necrosis is not encountered by
most surgeons or intensivists, but this complication carries a
signifi cant mortality (86 %).
36
a
b
J.A. Maykel
c
Fig. 3.2 Malpositioned nasoenteric feeding tubes, highlighting the importance of verifying tip location prior to initiation of feeds. ( a ) Coiled tip
in proximal esophagus ( b ). Tip in mid-esophagus ( c ). Tip in right mainstem bronchus
3 Perioperative Nutrition Support in Colorectal Surgery
37
Total Parenteral Nutrition
Key Concept : Underlying problems with the available literature regarding perioperative TPN use make widespread reliable conclusions diffi cult . Surgeons should be aware of
proper formulation and practice guidelines , as well as the
potential complications that can arise with the use of TPN .
Unfortunately, the literature that evaluates the role for
parenteral support is typically old, employing outdated practices and generally of low quality due to heterogeneous
patient populations, variable study designs, and excessive
feeding protocols. Early studies and subsequent metaanalyses have revealed confl icting results.
Von Meyenfeldt et al. published one of the earliest randomized controlled trials evaluating the impact of preoperative TPN on postoperative morbidity [ 42 ]. The authors
randomized 50 patients to 10 days of preoperative TPN and
50 patients to 10 days of preoperative enteral nutrition. These
patients were compared to a group of 50 malnourished control patients. The investigators observed a signifi cant
decrease in postoperative complications in patients who
administered preoperative nutrition and were high risk
(>10 % weight loss and >500 cc blood loss) ( p < 0.05).
In 1997, an expert committee reviewed all published studies evaluating the use of TPN in the perioperative setting [ 43 ].
When delivered preoperatively, TPN appeared to decrease the
risk of postoperative complications by 10 %, yet no difference in mortality was noted. When delivered postoperatively,
TPN was found to increase postoperative complications by
10 %, again with no mortality difference. Even at the time the
authors recognized that the type and quantity of nutrients
delivered were suboptimal and calories were given in excess
of metabolic needs, potentially impacting outcomes.
In 2000, Bozzetti et al. looked at the role of perioperative
TPN in malnourished gastrointestinal cancer patients. 90
patients with gastric or colorectal tumors and >10 % weight
loss were randomized to 10 days of preoperative and 9 days
of postoperative nutrition vs. control group [
group suffered fewer postoperative complications 37 % vs.
57 % ( p = 0.03) and fewer deaths (0 vs. 5, p = 0.05.). Even
though the patients were overfed at >35 kcal/kg, the overall
and infectious complications were fewer, likely as a result of
appropriate selection of highest risk, malnourished patients.
44 ]. The TPN
Complications
supplanting the triple lumen placed at the internal jugular or subclavian location. While considered safer with less risk of pneumothorax or injury to the chest vessels, PICC placement is not
benign and can still be complicated by misplacement, dislodgment, cardiac arrhythmias, thrombosis, and infection. Long-term
tunneled lines may be more resistant to infection, though are
more invasive with their own set of complications. All catheters
are at risk for infection, and this is a direct consequence of local
care and access technique. Thrombosis can complicate lines in
the upper extremities due to intraluminal thrombus or fi brin clot
at the catheter tip. If a catheter-related thrombosis is diagnosed,
the catheter should be removed and the patient systemically anticoagulated. Less common complications include pneumothorax,
vascular injury, air embolism, thoracic duct injury, brachial
plexus injury, and catheter erosion.
Metabolic
TPN should be considered a compounded medication and
therefore requires an understanding of its components and
risks of administration. While some institutions have “standardized” formulas or even nutrition support teams to guide
the prescription process, many surgeons are tasked with writing a customized solution on a daily basis. Inappropriate formulation can result in electrolyte abnormalities (commonly
including potassium and magnesium) as well as acid–base
disturbances. Excess calcium or phosphorus can lead to precipitation. Excess water can cause hyponatremia. One of the
most important issues related to TPN administration surrounds glycemic control. Excessive dextrose administration,
particularly to a diabetic patient or those on steroids, can iatrogenically create a state of hyperglycemia with signifi cant
impact of patient morbidity.
How to Write TPN
Key Concept : Matching the TPN formulation with the individual patient ’ s needs is an obvious , yet understated ( and
underperformed ), critical aspect to better outcomes .
This review of potential complications of TPN prompts a
review of a safe way to initiate and advance TPN. While each
institution varies regarding TPN formula options and compounding process, this review will highlight some of the
salient points that help the practitioner prescribe TPN in a
systematic and safe fashion (Table 3.2 ).
Catheter
The placement of a central venous catheter is necessary for the
initiation of total parenteral nutrition. The hyperosmolar solution
must be delivered into the large diameter, high-fl ow vena cava to
prevent phlebitis seen when delivered into the peripheral veins.
A PICC line is currently the most common form of access,
Enteral Versus Parenteral
Key Concept : When given properly and avoiding hyperglycemia , both the enteral and parenteral routes can adequately
provide ideal nutritional supplementation with similar
outcomes .
38
Table 3.2 Systematic approach to the safe and appropriate prescription of TPN ( may vary based on institution’s products and protocols )
Initial calculations
1. Determine the “feeding weight”:
Calculate ideal body weight (IBW)
Men : 106 lb for 1st 5 ft and 6 lb for each inch thereafter
Women : 100 lb for the 1st 5 ft and 5 lb for each inch thereafter
Compare to actual body weight (ABW) or usual body weight (UBW)
If a big discrepancy, calculate adjusted feeding weight
If patient is underweight, generally use IBW
If patient is obese (>120 % IBW), then add 25 % of the difference between the ABW and IBW to the IBW
Amputations
IBW less 6 % for BKA
IBW less 9 % for AKA
Using the example of a 70 kg person (“feeding weight”):
2. Calculate GOAL nutritional support. Usually
(a) Protein: 1.5 g/kg/day (1.5 × 70 = 105 g)
(b) Kilocalories: 25 kcal/kg/day (25 × 70 = 1,750 kcal)
3. Determine the components of the GOAL TPN admixture (no lipids/2:1)
(a) Start with total kilocalories
1,750 kcal
(b) Calculate how much of total kcal will come from goal protein
105 g × 4 kcal/g = 420 kcal
(c) Subtract this amount of calories from the goal/total
1,750–420 = 1,330 kcal.
(d) Make up the difference with dextrose
1,330 kcal ÷ 3.4 kcal/g = 390 g dextrose
4. Determine the components of the GOAL TPN admixture (with lipids/3:1)
(a) Start with total kilocalories
1,750 kcal
(b) Calculate 20 % (or 30 %) of the total calories, and provide this as lipids
1,750 × 0.2 = 350 kcal
350 kcal ÷ 9 kcal/g = 38 g (may round off to 35 g lipids (so lipids actually provide 315 kcal))
(c) Determine how much of total kcal will come from protein
105 g × 4 kcal/g = 420 kcal
(d) Subtract the protein and fat calories from the total and administer the remaining calories as dextrose
1,750 − 315 − 420 = 1,015 kcal
1,015 ÷ 3.4 kcal/g = 300 g dextrose
5. Final volume ( maximally concentrated)
(a) Amino acids (10 % stock solution) 105 g = 1,050 cc
(b) Dextrose (70 % stock solution) 300 g = 430 cc
(c) Lipids (20 % stock solution) 35 g = 175 cc
= 1,655 cc total
How to advance TPN safely
1. Day#1 “Starter Formula”: 1,000 cc/70gAA/150 g dextrose
Not much thought necessary as a start
Typically will test glucose tolerance, without signifi cant hyperglycemia
2. If tolerated (blood sugars <150 mg/dL), advance to day#2 formula:
1,000 cc/70gAA/210 g dextrose
Can also advance to goal protein safely if eager to move forward
3. If tolerated, advance protein to goal and then dextrose by 50 g/day (if hyperglycemia or diabetes) or 100 g/day until reach goal
4. Insulin administration:
(a) Rule
Cover dextrose in TPN with insulin in TPN (or SQ sliding scale)
Cover dextrose in tube feeds with sliding scale or NPH
(b) Typically it is safe to put 10 units in TPN for everybody
J.A. Maykel
3 Perioperative Nutrition Support in Colorectal Surgery
Table 3.2 (continued)
(c) Add up previous day’s sliding scale and add 2/3 of total to what is already in the current bag
(d) If advancing dextrose amount, increase insulin proportionally
(e) If hyperglycemic, do not advance dextrose until blood sugars are controlled (under 120–150 mg/dL)
(f) If diffi cult to control blood sugars because of insulin resistance, be quick to switch to an insulin drip, especially in the SICU
Electrolytes
1. Na: depends on volume status and losses
2. K: depends on urine output and losses
Typical urine: 20 or 40 mEq/L if on Lasix
3. Cl: maximize if metabolic alkalosis
4. Acetate: maximize if metabolic acidosis
5. Ca: RDA 10 mEq/day
6. Mg: RDA 10 mEq/day
7. Phos: RDA 30–40 mmol/day
Routine upon starting TPN ( day # 1 )
1. Start aggressive insulin sliding scale and QID BS checks for goal BS under 120 mg/dL
2. Check triglyceride level
Lipids contraindicated if >400 mg/dL
3. If on heparin, may add to TPN bag (6,000 units in TPN = 5,000 units SC BID)
4. If on Zantac, may add to bag (150 mg/day if normal renal function)
5. If on Reglan, may add to bag (40 mg/day if normal renal function)
6. Remember to reverse the above when stopping TPN
Some things to remember
1. Ca/phos solubility curve (can get chart from Pharmacy)
2. Lipid concentration must be at least 2 % (20 g/L)
3. If lipids in bag, total Ca and Mg sum must be ≤20 mEq/L
4. There is a minimum required volume for solubility, so use these two formulas to see if the macronutrients fi t:
Standard AA (AA × 7) + D + (L × 3.5) must be ≤ 70
If branched-chain AA (AA × 11) + D + (L × 3.5) ≤ 70
5. If using BCAA, maximum of 100 g/day
6. HCl cannot be added if lipids in bag
7. Remember kilocalories outside of TPN:
(a) Propofol is in a 10 % lipid emulsion, so you get 1 kcal/cc of propofol
(b) D5W for meds and treatment of hypernatremia
(c) Patients on CVVH(D) often have D5 solutions as return fl uid
(d) Patients on peritoneal dialysis
(e) Protein/calories from concurrent enteral feeds
8. Other potential additives:
Hydrochloric acid (HCl). Not compatible with lipids
Supplemental zinc (for open wounds, decubitus ulcers, or diarrhea)
Typically 10 mg/day
39
The literature over the past decades is replete with clinical
trials comparing enteral and parenteral nutrition. Some conclude that parenteral feeding is equivalent to enteral feeding
[ 45 – 47 ] while others conclude that enteral feeding is better
than parenteral feeding [ 48 – 50 ]. Absent a clear consensus,
post hoc analysis does reveal a common fl aw in many of the
studies purporting an advantage to enteral feeding. GI tolerance limits the total volume of solution that can be provided
to critically ill patients to about 1,500 cc/day. When study
goals are set at 35 kcal/kg/day, this can only be consistently
attained when parenteral nutrition is delivered through a central venous catheter. This dichotomy commonly sets up a
situation where enterally fed patients receive substantially
less energy than parenterally fed subjects. On the other hand,
providing parenteral nutrition at 35 kcal/kg/day or greater
produces hyperglycemia in the majority of patients [ 51 ].
Hyperglycemia clearly induces immunosuppression, resulting in an increased risk of postoperative complications and
adverse outcomes [ 52 ]. Van Den Berghe showed that in criti-
cally ill patients, all of who were adequately fed (approximately 25 kcal/kg/day either enterally or parenterally),
intensive insulin therapy aiming for euglycemia reduced
bloodstream infections by 46 % and overall mortality by
53 ]. There was no difference in outcome for those fed
42 % [
40
J.A. Maykel
exclusively enterally, exclusively parenterally, or with combined feeding with adequate control of blood glucose. This
fi nding underscores the fact that studies must properly compare feeding protocols that maintain equal glycemic control
and provide equivalent intakes of protein and calories for
both routes.
Since the 1991 Veteran’s Affairs study evaluating the effi cacy of preoperative TPN identifi ed an increased infection risk
in certain subgroups of patients [
54 ], there has been a general
recommendation favoring the use of enteral nutrition over
total parenteral nutrition. Closer examination of that study
reveals that it was actually a study of overfeeding in the TPN
group marked by resultant hyperglycemia. The total energy
intake of the TPN group was 46 kcal/kg/day (2,944 kcal/day)
while the ad libitum group consumed 20 kcal/kg/day
(1,280 kcal/day). Energy expenditure in such postoperative
patients would be estimated to be 25 kcal/kg/day [
55 ]. With
this degree of feeding-induced hyperglycemia, the immunosuppressive effects would be great enough to negate any
potential benefi t to preoperative feeding, with the exception of
the subgroup, which was severely malnourished. This was, in
fact, exactly and not surprisingly what was found.
More recent studies that provide patients with roughly
equivalent amounts of nutrients at modest levels demonstrate that there is essentially no clinical difference between
enteral and parenteral nutrition [
47 , 56 ]. For example, Braga
et al. designed a prospective RCT to evaluate the potential
clinical, metabolic, and economic advantages of enteral
nutrition over parenteral nutrition [ 46 ]. Two hundred and
fi fty-seven surgical patients were randomized to receive
early postoperative TPN or early postoperative TEN via a
jejunal feeding tube. Mean energy intakes were equal
between groups (1,632 ± 281 kcal TPN vs. 1,522 ± 317 kcal
TEN), and there was no difference in rate of hyperglycemia
(defi ned as serum glucose >200 mg/dL) (9.1 % TPN vs.
4.7 % TEN). Although enteral nutrition was found to improve
gut oxygenation (as assessed by cecal microprobe), there
was no difference in infectious complication rates, noninfectious complication rates, length of hospital stay, mortality, or
in nutritional, infl ammatory, or immunologic variables.
Most recently, Wu et al published a prospective randomized controlled trial evaluating the use of perioperative artifi cial nutrition in malnourished gastrointestinal cancer
(stomach, colon, and rectum) patients [ 57 ]. Four hundred and
sixty-seven elective patients who were moderately to severely
malnourished surgical by SGA were assigned to 7 days of
preoperative and 7 days of postoperative parenteral or enteral
nutrition vs. a simple control group. Patients were fed appropriately with 25 kcal/kg/day. Complications occurred in 18 %
of patients receiving nutrition and 34 % of control patients
( p = 0.012), and postoperative stay was longer in the control
group (23 days vs. 12 days, p = 0.0001). A mortality differ-
ence was also seen comparing study and control patients
(2.1 % vs. 6.0 %, p = 0.003). This study shows not only the
overall impact of nutritional support but highlights the importance of providing the appropriate quantity via the most
appropriate route over an adequate duration. Patients who
were unable to tolerate enteral nutrition were fed with TPN,
and combination regimens were utilized as well. There was
no difference in septic complications seen comparing enteral
and parentally fed patients (13 % vs. 16 %, p = 0.36).
Therefore, in the year 2014, it appears irrefutable that,
when delivered appropriately, both forms of nutritional support can be expected to improve organ function, immune
competence, and wound healing in appropriately selected
patients [
22 ].
Perioperative Management
Key Concept : Despite limited high - level evidence , preoperative
nutrition through either the enteral or parenteral route is likely
benefi cial , especially in the malnourished patient . Additional
benefi ts may be seen with immune - modulated formulas .
In colorectal surgery, patients who present in the malnourished state do so as a consequence of the underlying disease process, which affects the gastrointestinal tract.
Infl ammatory bowel disease, intestinal obstruction, large
tumors, fi stulizing diseases, and patients with diarrhea are
often unable to sustain themselves orally due to a poor appetite or resultant abdominal bloating and pain. This limits the
ability to intervene preoperatively, particularly when considering utilizing the enteral route. Oral nutritional supplements
that provide defi ned quantities of protein, calories, and vitamins can be offered and encouraged in almost every setting
but obstruction. These have been shown to improve postoperative outcomes. Appetite stimulants such as Megace can
help those patients with poor appetite but are unlikely to augment intake of these patients who are functionally obstructed.
Nasogastric tubes, nasojejunal tubes, and gastrostomy tubes
can be inserted and utilized. As most patients are defi cient,
an oral multivitamin/mineral supplement should be recommended for 2 weeks before surgery at 300–400 % the recommended daily values [ 58 ].
Unfortunately, the use of preoperative enteral nutrition
has not been well studied in either the well-nourished or malnourished GI surgery patient populations. A recent Cochrane
review [ 59 ] highlights this paucity of evidence and the real-
ity that many of the studies are outdated—with only two trials evaluating the administration of enteral nutrition (years
1992 and 2009) including only 120 participants and a high
risk of bias. Neither study showed any difference in primary
outcomes. The three studies that evaluated preoperative parenteral nutrition (years 1982, 1988, and 1992) showed a signifi cant reduction in postoperative complications,
predominantly in malnourished patients.
3 Perioperative Nutrition Support in Colorectal Surgery
41
Immunonutrition
Major injury, whether traumatic or surgery induced, results
in signifi cant metabolic and immunologic sequelae which
infl uence patient recovery. Specifi c “immune-modulating”
substances such as arginine, glutamine, nucleotides, and
omega-3 fatty acids/fi sh oil have been shown to modulate the
host response, resulting in improved immune function. The
clinical trials evaluating the effi cacy of these formulas have
supported an improved postoperative clinical course when
patients are compared to those receiving standard enteral formulas [ 60 – 62 ] and provide the only available studies evalu-
ating preoperative feeding.
In 1992, Daly et al. were the fi rst to study the clinical
effects of early enteral feeding with immune-enhancing diets
by prospectively randomizing 85 patients undergoing surgery for upper gastrointestinal malignancies to either a standard or experimental (Impact) enteral diet [ 63 ]. Postoperative
nutrition was delivered via a jejunostomy tube, starting on
POD#1 and continuing until POD#7. The two groups were
well matched and received equivalent volumes of tube feeds
(1,421 vs. 1,285 kcal/day). The patients who were administered the immune-modulating diet experienced a signifi cant
improvement in both postoperative wound healing and infectious complications, along with a shorter length of hospital
stay. The only fl aw in this study was that the patients were
fed isocalorically but not isonitrogenously (15.6 vs. 9.0 g of
Nitrogen per day), leaving the possibility that their fi ndings
may be partially explained by differential protein administration, although this is unlikely.
A recent meta-analysis consisting of 21 randomized controlled trials including 2,730 patients reviewed the literature
evaluating immunonutrition following major elective gastrointestinal surgery [ 64 ]. Immunonutrition decreased overall
complications when delivered before surgery (OR 0.48 CI
0.34–0.69), before and after surgery (OR 0.39 CI 0.28–0.54),
and after surgery (OR 0.46 CI 0.25–0.84). In the end there
were fewer infectious complications and shorter hospital
length of stay but no infl uence on mortality. The heterogeneity of the studies made it diffi cult to comment to the specifi c
role of malnutrition on outcomes. What does appear clear is
that if it is possible to give immune-modifying nutrition support early in the course of illness and to give it in rather large
amounts, its benefi ts are more easily detected.
Braga et al. similarly showed quite convincingly that the
administration of an immune-enhancing diet perioperatively
resulted in a signifi cant clinical benefi t [ 65 ]. They random-
ized 206 candidates for elective surgery to treat malignancies
of the colon, rectum, stomach, or pancreas to receive either
an immune-enhancing formula (Impact) or a control enteral
formula (isonitrogenous, isocaloric). Patients were administered 1 l per day for 7 days preoperatively followed by jejunal infusions of the same formulas postoperatively, starting
6 h after operation and continued until postoperative day 7.
The perioperative group experienced signifi cantly fewer
postoperative infections (14 % vs. 30 %) and a shorter hospital length of stay (11.1 days vs. 12.9 days). These fi ndings
were consistent, regardless of the baseline nutritional status,
and the authors concluded that the perioperative supplementation of immunonutrition provided metabolic and immunologic advantages that may be related to the ability to attain
adequate levels before the surgical insult. Because of the
preoperative feeding protocol, the formula intake was not
limited by postoperative gastrointestinal intolerance.
Total Parenteral Nutrition
The challenge with initiating TPN preoperatively deals with
the complexities of coordination. To safely and properly initiate TPN, a patient needs to be monitored for glycemic control, volume tolerance, and electrolyte abnormalities,
particularly when severely malnourished due to the risk of
developing the refeeding syndrome (development of electrolyte abnormalities, volume overload, and congestive heart
failure). Advancement of TPN from an initial formula to
goal formula often takes several days following placement
of a central venous line. It is nearly impossible to accomplish
this safely on an outpatient basis, yet it can be a challenge to
obtain insurance approval for hospital admission. Fortunately
most patients who are moderately to severely malnourished
(representing the population to theoretically benefi t most
from this approach) are commonly dealing with other medical issues that warrant hospital admissions, such as bowel
instruction, failure to thrive, or severe diarrhea with dehydration. While admitted, the surgeon can take advantage of this
opportunity to obtain central venous access and initiate
parental nutrition. Once goal formula has been reached and
other medical issues stabilized, the patient can be transitioned to a subacute care center or home with nursing support. Oftentimes the nutrition can be cycled to free the patient
and provide a “break” during the daytime hours. Once the
TPN has been started, there is less dependence on the
patient’s oral intake for nutritional support, and oral intake
can be considered a supplement to the protein and calories
being reliably delivered intravenously.
Postoperative Management
Key Concept : Nutritional support is not required in the
immediate resuscitative period following major surgery ;
however , it should be initiated shortly thereafter by whatever
route is more feasible .
During the immediate postoperative period, intravenous
nutritional support should be held. The body is recovering