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22
W.D. Buie and A.R. MacLean
In the urgent or elective situation, there are several factors that increase the risk of signifi cant postoperative cardiac
events such as myocardial infarction (MI), heart failure, and
death. These factors include unstable angina, severe angina
or recent MI (within 30 days), decompensated heart failure,
signifi cant arrhythmias, and severe valvular heart disease.
When these factors are present (especially in combination), a
very careful preoperative evaluation is required and may justify a delay in, or even preclude proceeding with, surgery. In
addition, there are a number of secondary clinical variables
that include a history of ischemic heart disease, cerebral vascular disease, compensated heart failure or prior heart failure, diabetes mellitus, and renal insuffi ciency, which are also
predictive for cardiovascular morbidity [
37 ]. While many of
them are incorporated into the clinical risk indexes outlined
below to give an overall risk score for the patient, they do
have independent associations with worse outcomes as well.
An evaluation of patient-specifi c risk also includes an
assessment of exercise tolerance. As noted previously, poor
exercise tolerance has been defi ned as the inability to walk
two to four blocks or climb two fl ights of stairs at a normal
pace due to the development of dyspnea, angina, or excessive
fatigue. This translates to a metabolic equivalent of ~4 (4
MET), and failure to achieve this is predictive of in- hospital
perioperative risk. Additional activities with a similar metabolic equivalent include carrying objects of 15–20 lb and
playing golf or doubles tennis.
The overall perioperative cardiovascular risk for each
individual patient is determined using one of several cardiac risk indexes. In 1977, Goldman was one of the fi rst to
develop a cardiac risk index using nine variables to predict
the development of cardiac complications [ 38 ]. Since then,
several others have come along—some cardiac-specifi c,
and others more general (i.e., ASA Classifi cation [ 39 , 70 ];
Table 2.3 ). Earlier, we introduced the Revised Cardiac Risk
Index (RCRI) or Lee Index, as it is one of the most widely
used due to its simplicity and clinical utility [ 40 ] (Table 2.2 ).
It is the primary index applied at our center and is based
on the presence or absence of six predictive factors: high -
risk surgery , ischemic heart disease , congestive heart fail-
ure , cerebrovascular disease , diabetes mellitus , and renal
dysfunction . Patients receive one point for each risk factor
that is present to give a cumulative index score. The rate of
development of a major cardiac event—defi ned as myocardial infarction, pulmonary edema, ventricular fi brillation/
cardiac arrest, and complete heart block—is estimated to be
0.4 % (95 % CI 0.1–0.8 %), 1 % (95 % CI 0.5–1.4 %), 2.4 %
(95 % CI 1.3–3.5 %), and 5.4 % (95 % CI 2.8–7.9 %) for
scores of 0, 1, 2, and ≥3, respectively [
41 , 42 ]. Using the
AHA algorithm, patients at high risk for cardiac complications (score ≥3) should undergo noninvasive cardiac (stress)
testing. If severe myocardial ischemia is identifi ed, coronary
revascularization should be considered prior to planned surgery (if possible), in addition to preventative medical strategies outlined below.
Recently, a new predictive risk model for perioperative myocardial infarction/cardiac arrest was constructed
from the American College of Surgeons National Surgery
Quality Improvement Program (NSQIP) database [
43 ].
This model is based on a very large patient cohort where
more recent preventive and interventional cardiac strategies
were applied. On multivariate regression analysis, signifi cant predictive variables included type of surgery, dependent functional class, abnormal creatinine, ASA class, and
increased age. This model is not as well known; thus, many
internists are not comfortable using it. However, when compared directly to the RCRI model, it demonstrated higher
predictive accuracy. An online calculator has been created
which makes it easy to apply by the surgeon to determine
individual risk [ 44 ].
Perioperative medical therapy for cardiac risk reduction
includes B-blockers, statins, and aspirin. High-risk patients
or those who take these medications preoperatively require
medical consultation. Based on recent evidence, preoperative B-blocker use has been limited to specifi c risk groups
and must be introduced gradually. Despite good evidence for
the benefi cial effect of B-blockers and statins [ 45 , 46 ], the
evidence for the perioperative use of aspirin and/or thienopyridine for the reduction of cardiac risk is less clear due to
an increased risk of perioperative bleeding. While aspirin
alone is safe, the combination of aspirin with thienopyridine
is associated with an increased risk of perioperative bleeding
and transfusion. To reduce the risk of bleeding, thienopyridine should be discontinued 5–7 days prior to surgery and
restarted as soon as the risk of postoperative bleeding has
decreased.
Table 2.3 American Society
of Anesthesiologists (ASA)
classifi cation
ASA1 A normal healthy patient
ASA 2 A patient with mild systemic disease
ASA 3 A patient with severe systemic disease
ASA 4 A patient with severe systemic disease that is a constant threat to life
ASA 5 A moribund patient who is not expected to survive without the operation
ASA 6 A declared brain-dead patient whose organs are being removed for donor purposes
Modifi ed from the American Society of Anesthesiologists (ASA) [
There are modifi cations—the addition of “E” for an emergency and the addition of “P” for pregnancy
70 ]
2 Perioperative Risk Assessment
23
High-risk patients with severe cardiac ischemia may be
candidates for preoperative coronary revascularization.
Patients with left main stem or three-vessel CAD associated
with poor left ventricular function have a recognized survival advantage with either coronary artery bypass (CABG)
or percutaneous coronary intervention (PCI) including balloon angioplasty and/or stent placement. The benefi ts and
risks of revascularization must be factored into the decisionmaking process. CABG has a higher procedural risk than
PCI. However, PCI with stent placement is associated with
an increased risk of perioperative bleeding due to the use of
dual antiplatelet agents, which, if stopped prematurely, may
result in stent occlusion. Ideally, colorectal surgery should be
delayed ~30–45 days after placement of a bare metal stent
and 1 year following a drug-eluding stent. This may not be
practical in a patient with a near obstructing cancer or in the
situation of a narrow therapeutic window following chemoradiation. Patients who require surgery within a month of
coronary revascularization should undergo either an angioplasty without stent placement or, in select circumstances, a
CABG. The colorectal surgeon must be involved in these
complex decisions, especially when determining the urgency
of the situation.
Pulmonary Risk Assessment and Risk Reduction
Key Concept : Perioperative pulmonary complications are
common and predictable and can be minimized with good
perioperative care .
Pulmonary complications are a major source of postoperative morbidity and mortality. In a large systematic review by
Smetana, the overall rate of signifi cant postoperative pulmonary complications was 6.8 % [ 18 ]. These included atelecta-
sis, pneumonia, bronchitis, respiratory failure (with or without
a need for mechanical ventilation), an exacerbation of underlying chronic lung disease, and bronchospasm [
Pulmonary risk assessment is based on patient-specifi c
factors and procedure-related factors. Recognized patientrelated factors include age >50 years, chronic obstructive
lung disease, congestive heart failure, obstructive sleep
apnea, poor general health (ASA >2), pulmonary hypertension, low oxygen saturation, and serum albumin <35 g/L [
48 , 49 ]. Additional variables that are contributory, but not
as well defi ned, include hypocapnea, abnormal chest X-ray,
smoking within the previous 8 weeks, and an active upper
respiratory tract infection. From a procedural point of view,
patients undergoing emergency surgery or prolonged major
abdominal surgery (>3 h) such as a colon resection are considered to be at high risk of postoperative pulmonary complications [ 50 , 51 ]. If you are prone to using a Pfannenstiel
incision for many of your abdominal cases, it is worth
18 , 47 ].
18 ,
noting that lower abdominal incisions are associated with a
decreased risk from a pulmonary standpoint. Additionally, a
Cochrane analysis of short-term outcomes in laparoscopic
vs. open colon surgery demonstrated improved pulmonary
function with the laparoscopic approach [
A complete history and physical examination is the cornerstone of preoperative evaluation for pulmonary disease.
You should look for signs and symptoms of occult respiratory disease, a recent exacerbation of known disease, and
symptoms of uncontrolled disease. The American College of
Physicians has published guidelines for preoperative evaluation and perioperative management of pulmonary risk [ 53 ].
Preoperative use of chest radiography and spirometry may
be indicated in patients with chronic obstructive lung disease (COPD) or asthma, but have not been shown to predict
the risk of postoperative pulmonary complications. Patients
with acute or chronic pulmonary illness should, in general,
have surgery postponed until their pulmonary disease is stabilized. What can help to a certain degree are a few straightforward things. First, excellent perioperative pain control is
paramount to encourage deep breathing and early mobilization. This may take the form of patient-controlled anesthesia or an epidural and should be discussed with anesthesia
preoperatively. Second, we try to get patients mobilizing as
soon as possible, often within the fi rst 6–12 h postoperatively. All patients undergoing abdominal procedures are
instructed preoperatively in deep breathing exercises and/or
incentive spirometry. While these may seem trivial, there is
likely no better thing you can get your patient to do other
than get out of bed and breathe. In contrast, there is no evidence to support the use of pulmonary artery catheterization
or total parenteral nutrition to reduce the risk of pulmonary
complications.
52 ].
Chronic Renal Failure Risk Assessment and Risk Reduction
Key Concept : When dealing with patients with chronic renal
failure , you must be careful to avoid exacerbating their renal
function with contrast imaging , ill - guided perioperative fl uid
management , and / or medications . These patients also have
higher rates of postoperative morbidity and mortality and
should be counseled accordingly .
The rate of chronic renal failure in patients over the age of
60 is approximately 25 % [ 54 ]. Chronic renal failure (CRF)
includes a broad spectrum of diseases that can range from a
decrease in a patient’s glomerular fi ltration rate (GFR) below
60 mL/min to end-stage renal failure with dialysis dependence. Important issues to consider in these patients include
avoiding situations that will worsen renal function (particularly in those who are not dialysis dependent), recognizing the potential for additional comorbidities (i.e., ischemic
24
W.D. Buie and A.R. MacLean
heart disease), and identifying the increased risk of perioperative morbidity and mortality.
Although an unenhanced CT scan provides far less information, we generally try to avoid intravenous contrast,
whenever possible, in patients with renal failure who are not
dialysis dependent but with underlying borderline renal
insuffi ciency. Options include non-contrast CT scans, MRI,
and/or ultrasound. When a contrast-enhanced scan is necessary in a patient with a GFR below 60 mL/min, and especially below 45 mL/min, nephrotoxic medications (including
metformin) should be held for 48 h pre- and post-contrast (if
at all possible). Intravenous hydration prior to the scan provides additional protection. Of note, N -acetylcysteine is now
proven to be largely unhelpful and should not be relied upon
in isolation to decrease the risk of contrast-induced nephropathy [
55 ]. In patients who are already on dialysis, we gener-
ally utilize IV contrast if indicated and arrange for the patient
to undergo dialysis post-contrast.
If a bowel preparation is required, it is important to provide clear instructions to these patients to avoid the risk of
preoperative dehydration. We typically utilize a split dose
polyethylene glycol preparation in these situations and make
sure that patients understand the need to consume regular
amounts of oral fl uids in addition to the prep.
Patients with chronic renal failure often have multiple
comorbid illnesses and thus require careful and complete
preoperative assessment to optimize their safety. We feel that
all of these patients require a preoperative internal medicine
consultation. In patients with CRF who do not have known
cardiac disease, the clinician should have a high index of suspicion of subclinical ischemic heart disease. We and others
have demonstrated a higher risk for perioperative morbidity and mortality [ 56 ]. In this cohort, it is worth noting that
mortality following elective colorectal surgery is ~5–10 %
and can range up to 40 % following emergency colorectal
surgery. These risks must be taken into consideration when
consenting patients with chronic renal failure for surgery.
Diabetes Mellitus Risk Assessment and Risk Reduction
Key Concept : Diabetic patients have high rates of additional comorbidity and are more likely to be asymptomatic .
Therefore , keep a high degree of suspicion . Diabetics also
have higher rates of surgical site infection , which can be
minimized by good glycemic control .
Diabetic patients also have a spectrum of disease, ranging
from mild diet-controlled diabetes to type 1 insulindependent diabetes. Greater than 8 % of the US population
are now diabetics. Approximately 50 % of diabetics will
require surgery at some point in their lifetime, and it’s estimated that 20 % of surgical patients have diabetes. A study
using the National Inpatient Sample showed that 15 % of
patients undergoing screening for colorectal cancer between
1998 and 2005 were diabetic [
Patients with long-standing diabetes often have additional
comorbidity, which is sometimes occult. Diabetics have
higher rates of cardiovascular disease, and more concerning,
diabetic patients who have ischemic heart disease are more
likely to be asymptomatic than nondiabetics. Thus, you need
to have a high degree of suspicion, and a lower threshold,
for formal preoperative cardiac evaluation in this cohort.
Diabetic patients also have higher rates of nephropathy, so
care needs to be exercised when using potentially nephrotoxic medications and contrast agents.
When possible, we have our diabetic patients scheduled
as the fi rst case in the morning to minimize the duration of
their fast and the disruption to their diabetic routine. Patients
on oral hypoglycemic medications can generally hold their
medication in the morning of surgery. Insulin-dependent
diabetics can generally be advised to take half of their regular morning dose. It is often helpful to have the patient’s
primary care physician or a consulting general internist
make specifi c recommendation for their diabetic medications perioperatively. Patients with type 1 diabetes are insulin defi cient and prone to developing ketosis and acidosis, so
they need long- acting insulin regardless of where their glucose readings lie. If they will be unable to eat, they also
require glucose in their IV fl uids (we typically use
D5/0.45NS +20 mEq/L KCl).
Finally, diabetic patients are at higher risk of surgical site
infections following colorectal surgery [ 58 ]. This is particu-
larly true for patients whose HbA1C levels are greater than
7 %. Both the American Diabetes Association and the
Canadian Diabetes Association have clinical practice guidelines that suggest keeping random glucose readings below
180 mg/dL (10 mmol/L). While we do not necessarily change
our practice (as we are diligent about wound care in all
patients), wound redness in a diabetic is likely a problem and
may need to be opened, cultured, and given antibiotics as
indicated.
57 ].
Hepatic Failure Risk Assessment and Risk Reduction
Key Concept : Patients with cirrhosis who require colorectal
surgery are at increased risk of perioperative morbidity and
mortality . When assessing a patient with known cirrhosis for
surgery , it is critical to take into consideration the natural
history of the disease state in question , the life expectancy of
the patient , and whether the patient is a candidate for liver
transplantation . Most importantly , both the surgeon and the
patient should have a realistic expectation of the morbidity
and mortality risk associated with the surgery .
2 Perioperative Risk Assessment
25
While the number of patients with cirrhosis who require
colorectal surgery is currently low, that number will likely
increase signifi cantly in the near future. In addition to the
known conditions that lead to cirrhosis, the increasing prevalence of obesity has led to approximately one-third of the US
population having nonalcoholic fatty liver disease, of which
about 20 % will develop nonalcoholic steatohepatitis
(NASH). This in turn will likely lead to many more patients
with signifi cant liver disease, as approximately 20–30 % of
adults with NASH will develop cirrhosis.
There are two clinical scoring systems that are commonly
used to estimate a cirrhotic patient’s perioperative mortality
risk: the Child-Turcotte-Pugh classifi cation, which was initially used to estimate risk in patients undergoing portosystemic shunt procedures, but more recently has been shown to
be valid in other abdominal surgery [
End-Stage Liver Disease or MELD score [
score is complex to calculate without electronic means, but
is the result of the following formula: MELD = 3.78 × (bilirubin mg/dL) + 11.2 × INR + 9.57 × creatinine mg/dL + 6.43.
Fortunately, several websites are available where patient values can be inputted and a risk estimate can be immediately
provided, including that of the authors of the original paper
at the Mayo Clinic [
One of the more diffi cult situations in colorectal surgery
is the discovery of a colorectal cancer in a patient waiting for
liver transplantation. The presence of a malignancy automatically removes the patient from the transplant list. To be eligible for reinstatement, a 5-year disease-free period is
required. This requires a thorough evaluation of the risks,
potential morbidity and mortality, as well as the life expectancy of the patient with respect to the tumor and the hepatic
failure (both with and without the transplant). A multidisciplinary discussion including the surgeon, the transplant
team, and the hepatologist, along with the patient, is required
so that proper and realistic decisions can be made on an individual basis.
61 ].
59 ] and the Model for
60 ]. The MELD
Important components of SSI prevention include preoperative antibiotics, appropriate skin preparation, maintenance of normothermia, avoiding hyperglycemia, and good
postoperative care [ 63 ]. Likely one of the easiest, yet often
missed, is ensuring the prophylactic antibiotics are administered within 1 h of the skin incision. We typically use cefazolin and metronidazole. In patients with B -lactam allergy,
gentamicin can be substituted for cefazolin. Patients known
to be colonized with MRSA require vancomycin instead of
cefazolin. Cefazolin should be re-dosed in cases lasting
greater than 3 h or with signifi cant blood loss. Metronidazole
is typically re-dosed for cases lasting longer than 8 h.
For skin preparation, avoidance of shaving is important,
especially the night prior. If hair removal is required, clippers should be used in the operating room prior to surgery.
Although chlorhexidine wash has been recommended, the
results of a Cochrane analysis showed that chlorhexidine
preparation did not demonstrate a signifi cant reduction in
SSIs [
64 ]. There is also confl icting evidence for the use of
wound protectors, though data does support its use for
decreasing SSI in colorectal surgery [ 65 ]. Our standard prac-
tice includes the routine use of clippers for hair removal,
chlorhexidine-alcohol skin prep, when possible, and selective use of wound protectors.
Maintenance of normothermia is an important component
for SSI prevention. Two randomized controlled trials have
demonstrated a signifi cantly reduced incidence of SSI in
patients who are kept normothermic by active warming
methods, and they are generally a component of most pathways aimed at reducing SSIs [ 66 ]. We use warmed fl uids and
forced air warmers to maintain normothermia. In addition,
there is an emerging body of literature for colorectal patients
that supplemental and high FiO 2 is associated with lower
rates of SSI [ 67 ]. Finally, as stated above, it is imperative to
maintain tight glucose control pre- and perioperatively to
help reduce the risk of infection.
Surgical Site Infection (SSI) Risk Assessment and Reduction
Key Concept : Surgical site infections are common following
colorectal surgery . Steps to minimize the risk , particularly in
the high - risk patient , are essential .
Colorectal surgery is associated with a relatively high
rate of SSI. A few (of several) factors that have been shown
to increase the risk include DM, obesity, open surgery, longer operative time, and emergency surgery [ 62 ]. While
most of the factors associated with SSI are not modifi able,
it is important to recognize the risks and to use the best
practice patterns to minimize the likelihood of SSI in these
patients.
Anastomotic Leak: Risk Assessment and Risk Reduction
Key Concept : Diverting stomas decrease both the incidence
and the consequences of high - risk anastomoses and should
be considered in distal rectal anastomoses .
While there is a detailed review on anastomotic leak by
Dr. Fleshman elsewhere in this text, a few brief notes are
worth mentioning in the context of risk assessment (and
mitigating it). There are many situations where an anastomosis is considered to be at increased risk of leak. Aside from
technical issues at the time of surgery, commonly implicated
patient factors include prolonged operative time, signifi cant
blood loss or need for transfusion, low rectal anastomosis,
male sex, steroid use, weight loss, low albumin, obesity,
26
W.D. Buie and A.R. MacLean
ASA class >3, smoking, COPD, and emergency surgery [ 68 ].
When more than one of these factors is present, the risk of
anastomotic leak is increased.
Diverting stomas had previously been felt to decrease the
consequences of a leak, but not the incidence. However, a
Cochrane review by Montedori and colleagues in 2010 demonstrated that a diverting stoma decreases the leak rate, as
well as the need for urgent reoperation [
69 ]. When deciding
on whether a patient would benefi t from a defunctioning
stoma, our approach has been to try to estimate a patient’s
risk of leak considering the risk factors as temporary (modifi able) or permanent (non-modifi able). In the presence of
several modifi able factors, the subsequent stoma closure
would be expected to have a signifi cantly lower risk of leak
than the anastomosis being protected. However, when the
factors causing concern for an increased risk of anastomotic
leak are non-modifi able, a diverting stoma for anything other
than high-risk distal rectal anastomoses is likely not helpful,
as there will still be a risk of leak at the time of loop stoma
closure. In those situations, if the risk of leak is felt to be suffi ciently high, consideration should be given to a permanent
stoma.
Risk Evaluation and Informed Consent
Prior to obtaining informed consent, the patient and the surgeon must have a clear discussion of the risks and benefi ts of
the surgery. This discussion may take place at the time of the
fi rst visit prior to signing consent if the patient is healthy or
of moderate risk. In the case of a high-risk patient, the discussion should occur after the medical evaluation is complete and all risk reduction strategies have been put into
place. At this time, the surgeon can evaluate the overall
patient risk profi le including patient, procedural, and anesthetic risks and review these with the patient. Additional factors that must be considered include the present disease state,
the potential for recurrent disease or symptoms, and the possibility of disease progression. It is extremely important that
your patient has a clear understanding of the treatment, risks,
and decisions that are being made. In situations of excessive
risk, the surgical plan may have to be altered and compromised, or in some cases, a nonoperative approach may be
appropriate.
Summary Pearls
Perioperative risk assessment is an essential part of sound
surgical decision making. As the surgeon, you must perform a basic screening examination to assess your patient’s
overall health and fi tness for surgery and obtain appropriate
consultation when required. With a thorough understanding
of their underlying health issues, interventions (where possible) to optimize their overall condition can be undertaken.
Ultimately, it is your responsibility not only to ensure that
each patient has their procedure selected to effectively treat
the disease process in question but also to perform the procedure as safely as possible to minimize perioperative morbidity and mortality.
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Perioperative Nutrition Support in Colorectal Surgery
Justin A. Maykel
Key Points
• In the year 2014, malnutrition remains prevalent yet
under recognized in surgical patients.
• The timely and appropriate delivery of nutritional
support to malnourished patients decreases postoperative complications, shortens hospital length of
stay, and may decrease postoperative mortality.
• While the enteral route is preferred when feasible,
total parenteral nutrition is safe and provides equivalent benefi t when delivered appropriately.
• Perioperative feeding of malnourished patients
appears to be the most effi cacious approach but can
be diffi cult to coordinate and deliver.
With proper use of total parenteral nutrition when necessary and use
of the gastrointestinal tract when possible, malnutrition need no
longer add to the morbidity and mortality of surgical patients.
Josef E. Fischer
AJS, 1980
Introduction
In the early 1970s, the widespread prevalence of proteincalorie malnutrition in hospitalized patients was defi ned [ 1 , 2 ]
and recognized to have a major infl uence on clinical outcome,
specifi cally patient morbidity and mortality [ 3 ]. Subsequently,
there have been extraordinary advances in the fi elds of surgical
J. A. Maykel , MD
Division of Colorectal Surgery, Department of Surgery ,
UMass Memorial Medical Center,
University of Massachusetts Medical School ,
Worcester , MA , USA
e-mail: justin.maykel@umassmemorial.org
3
nutrition and metabolism. Today, invasive nutritional therapies are commonly employed in hospitalized patients and virtually universal in the critically ill. Enteral access techniques
and specialized formulas have revolutionized the ability to
use the GI tract to support the metabolic responses to systemic injury, infl ammation, and infection. Central venous
access techniques and technologic advances in total parenteral nutrition (TPN) components and compounding make it
possible to provide nutritional and metabolic support when
the enteral route is inaccessible or functionally inadequate. In
the fi eld of colorectal surgery, we are commonly faced with
challenging patients who are malnourished due to advanced
malignancies or infl ammatory bowel disease that result in
intestinal blockages, intestinal fi stulas, poor absorptive capacity, and large volume losses from the GI tract. The literature
continues to evaluate the role for nutritional support in both
chronic disease and acute illness, delivered via the enteral and
parental routes, and in the preoperative and postoperative settings; yet, there are few studies that concentrate exclusively
on colorectal disease and colorectal patients. Additionally
there is marked heterogeneity involving study design, patient
populations under investigation (degree of malnutrition, disease process, etc.), and feeding protocols. Using published
studies and personal experience, I will attempt to give the
reader an understanding of the overreaching concepts while
detailing those scenarios most commonly encountered by the
practicing surgeon.
Prevalence and Impact of Malnutrition
Key Concept : While the overall prevalence of malnutrition is
high , it remains woefully unrecognized and unaddressed in
many of the highest at - risk patients . Poor nutritional status
directly correlates with worse outcomes .
Specifi cally looking at patients undergoing gastrointestinal surgery, the prevalence of malnutrition can be as high as
50 % [ 4 ]; yet, it remains unrecognized in upwards of 50 % of
patients who are at considerable nutritional risk [ 5 ], refl ecting
S.R. Steele et al. (eds.), Complexities in Colorectal Surgery,
DOI 10.1007/978-1-4614-9022-7_3, © Springer Science+Business Media New York 2014
29
30
J.A. Maykel
a generalized lack of appreciation and understanding of the
extent and importance of the problem. Additionally, the
degree of malnutrition worsens during the course of hospital
admission, particularly after 16 days, highlighting the importance of ongoing assessment and appropriate intervention
[ 6 ]. This may be due to illness or inadequate consumption of
delivered hospital food [
7 ]. Nutritional risk tends to be a
refl ection of the patient’s overall health and, in oncology, has
correlated with the primary tumor site (i.e., worse with
esophageal), higher Eastern Cooperative Oncology Group
score (range 0–5), and the presence of anorexia or fatigue
[ 8 ]. Such nutritional risk is associated with increased postop-
erative complications, longer length of stay, and higher mortality following elective surgery [ 9 ] and is particularly
pronounced in patient with colorectal cancer [ 10 ].
Patient Assessment
Key Concept : Although several instruments are available to
help assess nutritional status , nothing is more effective than
specifi c fi ndings on routine history and physical examination .
The initiation of invasive nutritional support should be
based on a comprehensive, up-front nutritional assessment.
Several objective options exist and have been studied over
time including body composition analysis (bioelectrical
impedance, displacement, exchange of labeled ions, total
body counters, magnetic resonance imaging, and computed
tomography), anthropomorphic measurements (creatinine
height index, triceps skinfold thickness, arm muscle circumference), biochemical measurements (serum proteins, nitrogen balance, protein breakdown, measurements of
immunologic function), and indirect calorimetry. The vast
majority of these studies are of historical signifi cance and are
rarely used currently outside of investigative studies.
Practically speaking, the evaluation of the potentially
malnourished patient begins with the history and physical
examination. Most patients will complain of some degree of
intolerance of oral intake as a result of poor appetite, nausea,
abdominal bloating, abdominal pain, and weakness.
Symptoms may be exacerbated by drug side effects and
interactions as well as the hypermetabolic state often seen
with advanced cancers and infl ammatory conditions. Patients
will relate a recent weight loss, typically over a 1- to 3-month
time period. On physical examination, you will fi nd the
patient appearing thin, pale, and weak with muscle wasting
and loose skin. These variables can be objectifi ed using grading systems such as the relatively intuitive Subjective Global
Assessment (SGA) to classify patients as well nourished,
moderately malnourished, or severely malnourished [
The SGA utilizes fi ve features of the history (weight loss
over 6 months, dietary intake change, gastrointestinal symptoms, functional capacity, and the impact of disease on nutritional
11 ].
requirements) and four features of the clinical exam (loss of
subcutaneous fat, muscle wasting, ankle edema, sacral
edema, ascites) to elicit a SGA rank based on subjective
weighting. Any practitioner should be able to use such an
intuitive system to assess patients with ease and with a high
degree of inter-rater agreement [ 12 ]. Similarly, the Nutritional
Risk Index (NRI) uses weight loss and serum albumin to calculate a score which can classify a patient’s nutritional status, NRI = (1.489 × serum albumin, g/L) + (41.7 × current
weight/usual weight) with the usual weight defi ned as the
stable weight 6 months or more before illness. The nuances
of other screening tools such as the nutritional risk screening
(NRS) 2002 and Reilly’s NRS remain controversial regarding predictive ability and clinical utility. It is important to
note that while a patient may appear obese on exam or by
BMI, depletion of protein stores can still render them
malnourished.
Albumin
Key Concept : Trending albumin over time ( i . e ., weeks ) may
be benefi cial , but in the acute setting albumin levels have
several physiological - based limitations .
Serum albumin level has been considered the “classic
test” which refl ects overall nutritional status, with serum
concentration of <3.0 g/dL defi ning the malnourished state.
However, in real practice, its utility and reliability is limited.
This is a very important point to be stressed. As a serum protein, levels fl uctuate for many reasons, including production
alterations in the catabolic or anabolic states, external losses,
or redistribution between the various fl uid compartments of
the body [ 13 ]. As such, a low value may refl ect either
decreased synthesis or increased degradation. What is well
known is that albumin levels fall precipitously in the setting
of metabolic stress and sepsis. During the acute phase
response, certain proteins (such as IL1, TNF, and CRP)
increase to help facilitate the immune response to eliminate
microbes, control tissue damage, and initiate the repair process. Albumin is a serum protein that decreases during the
acute phase response, apparently serving as “metabolic compensator” and helping to minimize transport of nutrients to
microbes. When patients are fl uid overloaded with increased
extravascular space, albumin shifts from the intravascular
fl uid into the interstitium where it is diluted and degraded.
Other short turnover proteins such as prealbumin, transferrin, and retinol-binding protein have similar limitations as
nutritional markers as a result of variable half-lives and
response to dietary intake and renal/liver dysfunction,
although all of these proteins can be useful when followed as
trends over time. Such trending can be particularly helpful
when patients are receiving apparently adequate nutrition,
but the serum albumin level remains low or even falls over
3 Perioperative Nutrition Support in Colorectal Surgery
31
time. This should prompt a comprehensive investigation
looking for a source of infection that is preventing the patient
from recovering from a catabolic state. This may be due to an
obscure infection such as an undiscovered intra-abdominal
abscess, persisting bacteremia, or inadequately treated colitis. In a recent review, higher baseline serum albumin was
found to predict improved survival for patients with cancer
of the gastrointestinal tract; however, causality has not been
shown as preoperative intravenous infusion has not been
shown to impact overall mortality [
14 ].
When discussing the nutritional state of a patient, the
standard question heard is: “What is the albumin or prealbumin level?” You should not let the discussion end there.
Rather follow with these questions: “What is the patient’s
hydration status? Is the patient acutely ill? Is there an ongoing infection? Has the patient lost weight over the preceding
3 months?” If the patient is coming to the offi ce from home,
in the well-hydrated state without active infection, then a
low serum albumin can be refl ective of their overall nutritional state. In any other situation, it is an unreliable predictor of nutrition when taken out of context alone and more
likely represents a refl ection of overall illness severity. When
a patient is acutely ill or even healthy but involved in a major
trauma, you should expect (and predictably will fi nd) albumin levels of <3.0 g/dL. While low serum albumin is widely
recognized as a risk factor for postoperative morbidity, it
remains generally undetermined if this correlation is a refl ection of overall systemic illness, nutritional status, or a combination of both.
Nitrogen Balance
Key Concept : Nitrogen balance is calculated easily and can
provide insight into the patient ’ s catabolic ( or anabolic )
state to help guide feeding regimens or prompt additional
evaluation for occult sources of ongoing sepsis .
The change in total body protein can be assessed by
estimating nitrogen balance, as 16 % of protein is nitrogen
and almost all body nitrogen is in protein. The calculation of
nitrogen balance can be useful, particularly in patients who
require prolonged nutritional support due to intestinal failure
or those who do not appear to be responding to adequate
protein and calorie administration. In the clinical setting,
nitrogen balance is calculated by determining the total nitrogen intake and the total losses via urinary, skin, and gastrointestinal losses. An accurate 24-h urine collection and total
protein intake are the only necessary data points:
Intake – loss (urine 90 %, stool 5 %, integument 5 %)
[ Protein intake (g)/6.25] – urinary urea (g) – 2 (stool and
skin) – 2 (non-urea nitrogen)
While a positive value is indicative of an anabolic state, a
negative value represents a persisting state of catabolism.
Table 3.1 Common baseline markers of malnutrition
BMI <18 kg/m 2
Weight loss >10 %
Low SGA score
Nonstressed state serum albumin <3.0 g/dL
This can be as a result of underfeeding or, commonly, due to
a persisting source of stress such as inadequately treated
infection or persisting low-grade sepsis. With comparisons
over time (i.e., week to week), a failure to convert to an anabolic state may prompt manipulation of feeding formulation
or delivery mode or may even prompt further investigation of
ongoing sepsis (similar to a persisting low albumin level).
In the critical care setting, indirect calorimetry, utilizing
the metabolic cart, can be very useful to determine energy
expenditure, the potential of overfeeding, and the relative
contribution/utilization of protein, carbohydrates, and fat to
overall metabolism. This data is commonly obtained and
interpreted by an experience critical care team helping to
care for critically ill patients in partnership with the colorectal surgeon.
Cancer Cachexia
Similar to the stress response, it is worth mentioning the cancer cachexia syndrome as it is prevalent and associated with
reduced physical function, tolerance of treatment, and survival [ 15 ]. This is refl ective of the patient’s physical appear-
ance. This was defi ned as a multifactorial syndrome with an
ongoing loss of skeletal muscle mass (with or without loss of
fat mass) that cannot be fully reversed by conventional nutritional support and leads to progressive functional impairment. Its pathophysiology is characterized by a negative
protein and energy balance driven by a variable combination
of reduced food intake and abnormal metabolism that is
driven by proinfl ammatory cytokines including interleukin
(IL)-1, (IL)-6, and tumor necrosis factor (TNF)-α. There is
evidence that “chronic infl ammation” as a result of lowgrade tumor-induced activation of the host immune system
shares several characteristics with the “acute phase response”
to injury (Table 3.1 ).
Initiation of Nutritional Support
Key Concept : Although relatively healthy patients may safely
wait several days prior to initiation of therapy , at - risk
patients or those with moderate insults achieve optimal outcomes with early implementation of nutritional support .
For the well or mildly malnourished patient with an ongoing moderate systemic infl ammatory response, initiating