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10
Asepsis, Sterilization and Disinfection
Sterilization
Disinfection
SU14.1: Describe aseptic techniques, sterilization and
disinfection.
SURGICAL PATIENT
In spite of scientific advances in understanding pathogenesis of various diseases and better understanding
of pharmacotherapy, infection remains the ‘number one’
enemy for surgeons. So, every attempt should be made
to minimise the infection rates in the ward, hospital and
in the operation theatre. Joseph Lister called infective
agents as disease dust and introduced carbolic acid
spray as an antiseptic agent. Hence, Joseph Lister is
called the father of modern surgery. This chapter deals
with fundamental principles of various methods of
sterilisation and disinfection and their usage in day-today clinical practice.
Sterilisation is defined as
object or surface is free of all microorganisms in the
vegetative form and in the spore state. This includes
viruses, bacteria, their spores and fungi.
Disinfection means
organisms capable of giving rise to infection. Rarely does
this process kill spores. Disinfection must never be used
when sterilisation is possible.
Asepsis means being free of sepsis.
Antisepsis means
the growth of bacteria in wounds or tissues.
prevention of infection by inhibiting
a process by which an article,
destruction of all pathogenic
Physical agents
Chemical agents
Key Box 10.1
Classification
Physical agents Chemical agents
1. Sunlight 1. Alcohol
2. Drying 2. Aldehyde
3. Heat 3. Dye
• Dry heat 4. Halogens
• Moist heat 5. Phenols and cresols
4. Filtration 6. Gases
5. Radiation 7. Surface-active agents
8. Metallic salts
PHYSICAL AGENTS
1. Sunlight
It is an example of a natural bactericidal agent which
causes sterilisation of tank water, rivers, etc. It is mainly
because of ultraviolet rays in addition to heat rays.
2. Drying
Drying in air has ill-effects on growth of bacteria. In
fact, 80% of weight of bacteria is due to water. However,
it does not affect spores and it is an unreliable method.
3. Heat
Heat is the most commonly employed and most reliable
method of sterilisation (Key Box 10.2).
Agents Used in Sterilisation
Key Box 10.1 gives the classification of agents used in
sterilisation.
Two Types
I. Dry heat
II.
Moist heat
34
Asepsis, Sterilization and Disinfection
35
Key Box 10.2
Heat
Most reliable
Rapid method of sterilisation
No harmful residue
I. Dry Heat
This method of heat kills the organisms by protein
denaturation and
oxidative damage.
Types
a. Red heat: Inoculating
loop or wires, tip of forceps
and needles are held in the flame of a Bunsen burner
till they become red hot.
b. Flaming: Glass slides, scalpels and mouths of culture
tubes
are passed through Bunsen flame a few times.
c. Incineration: This is used
to destroy soiled dressings,
bedding, bandages, etc.
d. Hot air oven is
the most widely used method of
sterilisation by dry heat (Key Box 10.3).
• Temperature required is 160°C
for one hour or
180°C for 20 minutes.
• Glassware, forceps, scissors, scalpel glass
syringe can be sterilized. Materials like oils,
greases, dry powder, etc. can also be sterilized
by this method.
Key Box 10.3
Hot Air Oven
Glass syringes, test tubes, pipettes
Metal forceps, scissors, scalpels
Oil, jelly, powder
Swab sticks
Sterilisation control—indicators
1. Spores of nontoxigenic strain of Clostridium tetani
2. Browne’s tube
3. Thermocouples.
II. Moist Heat
This method of heat kills organisms by coagulation and
denaturation of
their proteins.
In case of spores, steam condenses on it, increases its
water content, causes hydrolysis and breakdown of the
bacterial protein.
Types
A. At temperature below 100°C
a. Pasteurisation: Temperature o
f 63°C for 30 minutes
(holder method) or 72°C for 15 to 20 seconds (flash
method), followed
by cooling quickly to 13°C or
lower. Mycobacteria, brucellae and salmonellae are
destroyed by this method but spores are not
destroyed.
b. Inspissation: Serum or egg media (Lowenstein-
Jensen media) are sterilized in the inspissator at
80–85°C for half an hour on three consecutive days.
c. Vaccine bath: Vaccines of nonsporing bacteria are
sterilised in special vaccine baths at 60°C for one
hour.
B. At 100°C
a. Boiling (temperature 100°C):
Vegetative bacteria
are killed at 100°C but sporing bacteria require
considerable time for boiling. Hence, boiling is not
recommended for sterilising instruments.
b. Tyndallisation: Steam at 100°C for 20 minutes on
three consecutive days. It is used for sterilisation
of egg, serum or sugar containing media.
c. Autoclaving or steam under pressure (temperature
above 100°C): This is the most popular method.
Principle: Water boils when its vapour pressure
equals
that of surrounding atmosphere. When pressure inside
a closed vessel increases, the temperature at which water
boils also increases. When steam comes into contact with
cooler surface, it condenses to water and gives up its
latent heat to that surface. Condensed water ensures
moist conditions for killing the microbes present. All
the air must be removed from autoclave chamber before
autoclaving.
Temperature employed: Sterilisation is carried out between
108°C and 147°C.
Commonly, temperature of 121°C at
15 lb pressure for 15 minutes is used (Key Box 1.5).
• Thus dressings, instruments, laboratory-ware, media
be sterilised with autoclaving. However, it is not
can
suitable for bottled fluids.
Sterilisation control: Spores o
f Bacillus stearothumophilus
are used as test organism.
• Chemical indicators: Browne’s tubes
• Thermocouples
• Autoclave tapes.
4. Filtration
It is used to get rid of microorganisms from heat labile
liquids and substances such as sugars and urea, which
are used for preparation of media. Hence, it is useful
for antibiotic solutions, sera and carbohydrate
solutions used in the preparation of culture medium.
Different types of filter include earthenware filters,
asbestos filters, sintered glass filters, membrane filters,
etc.
Section I • Basic Principles of Surgery
36
Manipal Manual of Surgery
5. Radiation
a. Nonionising radiation: Low energy type, for example:
1. Infrared
radiation: Used for mass sterilisation of
syringes.
2. Ultraviolet radiation: This can be used to disinfect
hospital ward, operation theatre, viral laboratory,
etc.
b. Ionising radiation: X-rays, gamma rays are examples.
They have high penetration power and highly lethal
to all cells including bacteria. Gamma radiation is
used to sterilise plastic tubes, catheters, syringes,
culture plates, etc. This method is also known as cold
sterilisation, as there is no appreciable increase in
the temperature.
CHEMICAL AGENTS
Chemical agents act by protein coagulation and disruption of cell membrane. They are mainly used for
disinfection rather
than sterilisation.
Disinfectants are antimicrobial agents used to kill
potentially infectious agents present on inanimate
object, e.g. surfaces, water, etc.
Chemical disinfectants which can be safely applied
to skin or mucous membrane and are used to prevent
infection by inhibiting the growth of bacteria are called
antiseptics.
1. Alcohols
Ethyl alcohol (ethanol) and isopropyl alcohol are
commonly used. They rapidly kill bacteria, including
tubercle bacilli,
but they have no action on spores and
viruses. They are used in concentration of 60–70% in
water as skin antiseptics before a surgical incision.
• Isopropyl alcohol is better
than ethanol because it is
fat solvent, more bactericidal and less volatile. Hence,
it is used to disinfect clinical thermometers.
• Methyl alcohol is effective against fungal spores.
However,
it is toxic and inflammable and hence, not
used.
• 2% buffered solution is used.
• It has no deleterious effect on cement or lenses of
instrument.
• Commercially available as ‘Cidex’.
3. Dyes
• They are aniline dyes (Key Box 10.4) and acridines
which
are used as skin and wound antiseptics.
Acriflavine, proflavine are the examples for
acridine dyes.
• They act against gram-positive and gram-negative
organisms. They
are little, if at all, affected by
presence of pus.
• Whenever a cavity has to be packed or a tie over
dressing to be applied following
skin grafting,
gauze soaked in acriflavine can be used.
Key Box 10.4
Aniline Dyes
Brilliant green, malachite green, crystal violet
More active against gram-positive organisms
Pus inhibits their activity
4. Halogens
Iodine is a bactericidal agent with moderate activity on
spores.
It is also active against tubercle bacillus. Iodine
is used almost exclusively as a skin disinfectant
(antiseptic).
• Mixtures of iodine with surface-active agents that act
carrier for iodine are known as iodophores.
as
Betadine is an example of this. This is also active
against fungi, trichomonas.
• When chlorine or hypochlorites are added to water,
the chlorine reacts with water
to form hypochlorous
acid. It is a strong oxidizing agent and effective
disinfectant.
• Chlorine and hypochlorite solution (EUSOL) also are
other examples.
2. Aldehydes
They are bactericidal and sporicidal.
a. Formaldehyde (HCHO): This is used
to preserve
anatomical specimen. It is an irritant, water-soluble
gas.
• Formaldehyde gas is used to fumigate wards, sick
rooms, etc.
b. Glutaraldehyde: It is effective against tubercle bacilli,
and viruses. It is less irritant than formaldehyde.
fungi
• This is used to sterilise cystoscopes, bronchoscopes,
endotracheal
Section I • Basic Principles of Surgery
are heat-sensitive.
tubes and metal instruments, which
5. Phenols and Cresols
These are obtained by distillation of coal between
temperatures of
170°C and 270°C. They cause cell
membrane damage.
• Phenol (carbolic acid) was introduced first by Lister,
father of antiseptic
surgery. It is a powerful microbicidal substance. It is bactericidal at a concentration
of 1%.
• Lysol, cresols, chlorhexidine are also phenols. Chlor-
hexidine (hibitane) is nontoxic, skin
antiseptic, active
against gram-positive and also gram-negative organisms and moderately active against mycobacteria.
Asepsis, Sterilization and Disinfection
37
6. Gases (Vapour-Phase Disinfectants)
a. Ethylene oxide: It
is a highly inflammable, colourless
gas. Hence, it is mixed with inert gases such as carbon
dioxide or nitrogen so that its explosive tendency is
eliminated. It is highly lethal to all kinds of microbes
including spores and tubercle bacilli.
• It is used for sterilising heart-lung equipment,
books,
clothing, glass, plastic, etc. Thus routinely
used catheters such as Foley’s catheters, Ryle’s
tube, etc. are sterilised by ethylene oxide gas.
b. Formaldehyde gas: Used
for fumigation of operation
theatres and rooms, often after doing septic case.
c. Betapropiolactone: I
t is also used for fumigating
purposes. It is also active against viruses.
7. Surface-active Agents
Substances that alter energy relationships at interfaces
leading
to reduction of surface or interfacial tension are
known as surface-active agents or surfactants. They are
used as wetting agents, detergents, etc.
• The most commonly used preparations are cationic
surface-active agents. They are bactericidal. They have
no action on spores, tubercle bacilli, etc. Commercially
available
preparation include cetrimide (cetavlon).
They are most active in alkaline pH. Pseudomonas
aeruginosa is particularly resistant to these compounds.
• Soaps are also active against gram-positive and gram-
negative organisms.
8. Metallic Salts
The salts of silver, copper and mercury are used as
disinfectants. Mercurochrome is less toxic
and is used
as mild antiseptic.
Clinically it is used in the treatment of skin grafted
ulcers after the graft has taken up well.
• Few examples of sterilization are given in Key
Box 10.5
Key Box 10.5
Quick Revision of Sterilization of Commonly Used
Instruments in the Operation Theatre
Surgeon’s knife (scalpel) : Glutaraldehyde
Forceps, retractors, etc. : Hot air oven
Foley’s catheter : Gas sterilisation (ethylene
oxide)
Glass syringes : Hot air oven
Operation theatre : Formaldehyde gas
Clinical thermometer : Isopropyl alcohol
TESTING OF DISINFECTANTS
1. Rideal-Walker test: Phenol is taken as standard
disinfectant. Suspension of typhoid bacilli is subjected
to the action of varying concentrations of phenol and
the disinfectant to be tested and compared with
phenol.
2. Chick-Martin test: Disinfectant acts
in presence of
organic matter.
Section I • Basic Principles of Surgery
11
Nutrition in Surgical Patients
Causes of malnutrition
Consequences of malnutrition
Patient evaluation
Estimating energy requirements
Perioperative nutritional support
Immunonutrition
SU12.1: Enumerate the causes and consequences of mal-
nutrition in the surgical patients.
Introduction
The goal of nutritional support in the surgical patient is
to prevent or reverse the catabolic effects of disease or
injury and to ensure that their nutritional requirements
are met using the most suitable route with minimal
complications. The ultimate validation for nutritional
support should be improvement in clinical outcome and
restoration of function.
Nutrition is an important component of the care of the surgical
or critically ill patient. Malnutrition can be fatal. Overnutrition
can also be harmful. Provision of services of a physician, dietician,
microbiologist and good nursing care are vital to patient recovery.
Route of administration of nutrition
Enteral nutrition
Parenteral nutrition
Complications
CONSEQUENCES OF MALNUTRITION OR
PATHOPHYSIOLOGY OF GASTROINTESTINAL (GI) FAILURE
Autocannibalism: When gastrointestinal tract (GIT)
fails or during starvation, the existing energy stores are
consumed to supply energy.
undergoes glycogenolysis and gets depleted in 24 to
48 hours. Normal physiological functions of the organs
of an average adult at rest [Basal metabolic rate (BMR)/
Resting energy expenditure (REE)] need about 20 kcal/
kg/day. Therefore, when GIT fails, the fat in the adipose
tissue and protein in the muscles and viscera are
mobilised and metabolised to supply and sustain REE.
This is called autocannibalism (eating one’s own tissues
to survive). It weakens the muscles (e.g. respiratory and
cardiac muscles), viscera (liver, kidneys, etc.) and
immune system, resulting in increased morbidity and
mortality (Fig. 11.1).
Glycogen stored in the liver
CAUSES OF MALNUTRITION
1. Patient is not able to swallow/eat: Carcinoma oesophagus, carcinoma stomach
2. Anastomotic breakdown: Leak after Whipple’s
pancreaticoduodenectomy, after colonic or intestinal
resections
3. Enterocutaneous fistula
4. Small gut syndrome
5. Debilitating diseases: Crohn’s disease, intestinal
tuberculosis, advanced malignancies
Patients receiving intravenous (IV) fluids are semistarving: 500 ml of 5% dextrose containing 25 g of
dextrose provides about 100 kcal (each gram of
carbohydrate provides about 4 kcal), and, therefore, an
adult kept nil by mouth (NBM) and receiving 4–5 bottles
of 5% dextrose/day gets about 400–500 kcal. The balance
amount of REE (for a 50 kg individual, REE = 50 × 25
= 1250 kcal; 1250 – 500 = 750 kcal) comes from glycogen
for 24 to 48 hours and thereafter from autocannibalism
which is detrimental.
38
Nutrition in Surgical Patients
Fig. 11.1: Autocannibalism—case of enterocutaneous fistula
Fasting in healthy persons versus fasting in patients:
When resting healthy persons are fasting, the metabolic
rate drops to basal level. Although critically ill patients
who are kept nil by mouth (NBM) are also resting, their
basal metabolic rate is accelerated (hypermetabolic), and
their REE is increased proportionate to the level of stress
due to injury or illness.
PATIENT EVALUATION
Every patient admitted to the hospital must have their
nutritional status assessed to determine the severity of
nutrient deficiencies or excess and to predict the nutritional requirements.
A thorough history
• History of unintentional weight loss: Weight loss is
an important indicator of nutritional status. A recent
history of 20% weight loss indicates mild, 20 to 40%
moderate, and more than 40% severe undernutrition.
Body mass index (BMI) is another easily calculated
indicator. Mid-arm circumference and triceps skin fold
thickness are anthropometric indices that are useful.
Low serum albumin (3–3.5 g%—mild, 2–3 g%—
moderate, and <2 g%—severe undernutrition) is not
a sensitive indicator because of the long half-life and
a large pool size. Prealbumin, retinol-binding protein
and transferrin have shorter half-lives, smaller pool
size and are more sensitive indicators.
• History of chronic illness
• Dietary habits and any recent changes
• Medication intake
A complete physical examination
• Assess loss of muscle and adipose tissues by anthro-
pometric techniques such as skin fold thickness and
midarm circumference.
39
• Skin and hair changes
• Neuromuscular functions
• Any organ dysfunction
Biochemical determinants
• Albumin and prealbumin levels
• Transferrin levels
• Creatinine excretion
• Total lymphocyte count (assess immunologic function)
ESTIMATING ENERGY REQUIREMENTS
Several equations can be used to calculate the energy
requirement for a given individual. The most widely
accepted equation is the Harris-Benedict equation that
estimates the resting energy expenditure (REE) or the
basal metabolic rate (BMR).
In a normal resting physiological state, the BMR for
men and women is as follows.
Men:
BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height
in cm) – (6.775 × age in years)
Women:
BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height
in cm) – (4.676 × age in years)
Use of simple formulae such as 25–30 kcal/kg/day
to provide nutrients is also acceptable. Another method
is by using indirect calorimetry and calculation of
nitrogen balance. As surgical patients undergo physiological stresses, the value thus derived needs to be
multiplied by a stress factor to calculate accurate energy
requirements. For practical purposes, it is easier to
remember that the adult REE is 20 kcal/kg/day and it
increases to 25, 30, and 40 kcal/kg/day in mild,
moderate and severe stress.
Condition Stress factor
Moderate malnutrition
Minor elective surgery 1.1
Mild stress
Major elective surgery 1.2
Moderate stress
Skeletal trauma 1.4
Severe stress
Head injury 1.6
Severe burns 2
For example, a 55-year-old man, with a weight of
60 kg and a height of 170 cm, is undergoing major GI
surgery, then his basal caloric requirement is 30 × 60 kg
= 1800 kcal. A stress factor of 1.2 can be added for elective
major surgery, it becomes 2160, or roughly 2200 kcal.
Section I • Basic Principles of Surgery
40
Manipal Manual of Surgery
How much nutrition to be given: Sixty per cent of the
total calories should come from carbohydrates and 40%
from fats. These calories are nonprotein calories.
Calories obtained from proteins should not be taken into
account for calculating the energy needs because they
are building blocks in tissue repair and are not meant
for burning for calories. The protein requirement of the
resting adult is 0.8 g/kg/day, and it increases to 1.1,
1.5, and 2.1 g/kg/day in mild, moderate and severe
stress. Recommended daily allowances of vitamins,
minerals and trace elements are added to the
formulations. The daily intake and output of fluids
should also be calculated and balanced.
PERIOPERATIVE NUTRITIONAL SUPPORT
• Preoperative assessment of nutritional status must
be done in patients undergoing elective surgery and
nutritional support provided in those who are not
able to take it volitionally. Nutritional support
given to meet energy requirements for essential
metabolic processes and tissue repair, and to meet
substrate requirements for protein synthesis. A
healthy adult can withstand semistarvation (receiving
IV fluids only) for about 4 to 5 days without ill-effects.
Beyond this period, they need nutritional support in
order to prevent the adverse effects of autocannibalism. Many patients are nutritionally depleted at
the time of admission and will need nutritional
support much earlier.
• Cells can perform their function only when they get
nutrients and oxygen. When the nutrients are metabolised in the cells, the tissues get energy to perform
their physiological functions. Gastrointestinal system
(GIT) is the source of supply of nutrients (energy) to
all the tissues. It has to supply nutrients on a day-today basis because the body has limited expendable
reserves (stores). Lack of nutrients results in energy
crisis.
• In critical care units, priority is given to treatment of
hypoxia, haemorrhage, haemodynamic instability,
fluid, electrolyte, acid–base imbalance, and sepsis.
These deserve their priority, but hyponutrition and
the consequent energy crisis should not be ignored.
• In healthy, non-malnourished patients undergoing
elective surgery, the insult to metabolism begins
when the patient is kept NPO from midnight in
anticipation of surgery. In cases of GI surgeries, this
might be followed by a fasting period in the postoperative period also, leading to a starvation period
of more than 24 hours. This can strain the starvation
response, and must be prevented for best outcomes.
Section I • Basic Principles of Surgery
Recent enhanced recovery after surgery (ERAS)
protocols allow liquid intake up to 2 hours before
surgery, encourage carbohydrate loading preoperatively which help in dampening the metabolic insult.
In malnourished patients, although a total correction
of malnutrition before elective surgery may not be
possible, some form of preoperative intervention can
be impactful in selected patients. A few factors to be
considered are the indication for the surgery, whether
elective or emergency (should not risk delaying the
surgery to optimise the patient nutritionally in case
of life-threatening conditions), the patient’s level of
malnutrition, likelihood of it responding to preoperative nutrition and the available options for supplementation.
A few criteria that can be used to initiate preoperative
nutrition are:
• BMI <18 kg/m
2
• Unintentional weight loss of more than 10% of body
weight in 6 months.
is
• Serum albumin <3 g/dl
• If patient is expected to be unable to meet caloric
requirements for more than 7 days perioperatively.
• Catabolic diseases
ROLE OF IMMUNONUTRITION
• Patients undergoing elective surgery benefit from
preoperative initiation of immunonutrition as injury
induced by surgery leads to significant suppression
of immune function. It must be initiated 5–7 days
preoperatively for optimum benefit. Patients who
may benefit include severely malnourished patients
undergoing major oncologic GI surgery, head and
neck surgery, patients with severe trauma or burns.
Studies have shown that their administration is
associated with reduced rates of infection and other
complications, and shorter length of hospital stay.
The nutrients that have been proven to cause
improvement in immune functions include:
• Arginine: Supports T lymphocytes; provides sub-
strate for generation of nitric oxide
• Glutamine
• Omega-3 polyunsaturated fatty acids: Promotes
synthesis of favourable prostaglandins; decreases
production of inflammatory cytokines, etc.
ROUTE OF ADMINISTRATION OF NUTRITION
ENTERAL NUTRITION
It is paradoxical that sick patients who need to eat more
to meet the increased metabolic demands are often
unable to eat. They have anorexia, nausea, vomiting and
Nutrition in Surgical Patients
41
altered sensorium. Oral feeding is impossible in patients
with faciomaxillary injuries or those on ventilators. In
many of them, the intestines are functioning. Enteral
route is best for providing nutrition. Hence the dictum,
“When the gut is working, use it”.
• Enteral access: Following are the routes to introduce
nutrients into the GIT (Table 11.1):
– Nasogastric feeding (Fig. 11.3): When the stomach
emptying is normal and swallowing is impossible
or contraindicated, nasogastric feeding (Ryle’s
tube) provides nutrition.
– Nasojejunal feeding (Fig. 11.4): In gastric stasis,
feeding can be given through a nasojejunal (NJ)
feeding tube introduced either blindly, under
radiologic or endoscopic guidance to place its tip
in the jejunum (postpyloric).
– Feeding gastrostomy: By open method or by
percutaneous endoscopic gastrostomy (PEG) when
RT or NJ tube insertion is impossible.
– Percutaneous endoscopic gastrostomy (PEG): With
the help of an endoscope, a gastrostomy tube is
placed in a retrograde manner and brought out
through a skin incision. It is technically very easy
and can be done under local anaesthesia. It has
replaced feeding gastrostomies (open method). It
is popular nowadays (Fig. 11.2). Complications
include colonic perforation, sepsis, bleeding,
wound infection, etc.
– Feeding jejunostomy: After major/complex
operative procedures on the oesophagus, stomach
and pancreas, a feeding jejunostomy is frequently
established.
• What to feed: A number of preparations are commer-
cially available but most cost-effective ones are the
blenderised kitchen feeds. Enteral feeds are hyperosmolar and provide 1.2 to 2.0 kcal/ml.
– Polymeric feeds: These are commonly prepared in
the kitchen. Liquid and powder preparations are
commercially produced. These contain polysaccharides, polypeptides and oils. Soups of dal, vegetables and chicken are examples of polymeric feeds.
– Elemental feeds: These are predigested in vitro and
contain oligosaccharides, oligopeptides and
medium and long chain triglycerides (MCT and
LCT). They are useful in patients with irritable
bowel disease and short bowel.
– Modular feeds: Contain monosaccharides, amino
acids and fatty acids.
– Disease-specific feeds: The composition of the feeds
needs to be altered in certain disease states. Renal
failure—low protein, low/no electrolytes; hepatic
failure—more branched chain amino acids (BCAA)
and less aromatic amino acids;
respiratory failure—
more fats (55% cal) and less carbohydrates.
• How to feed: The feeds can be gravitated, injected
with a syringe or pumped into the tubes either
continuously or intermittently. Start with 50 ml every
2 hours on the first day and if tolerated, increase
gradually to 200 ml every 2 hours until the target is
reached.
Table 11.1 Feeding methods (Figs 11.3 and 11.4)
Ryle’s tube (RT) feeding
Easy, quick, cheap method
Indicated in stroke, comatose patients,
etc.
Chances of aspiration are high. Hence,
30° propped up position is recommended
Gastrostomy
Indicated when RT cannot be passed,
e.g. inoperable carcinoma oesophagus,
stricture
Malecot’s catheter is introduced into the
stomach and kept in place using a purse
string suture (Stamm’s gastrostomy)
Feeding jejunostomy
Indicated after major oesophageal
surgeries, high duodenal fistulae
A Ryle’s tube is introduced into the
jejunum under vision (during surgery)
and kept in place using a purse string
suture
Fig. 11.4: Feeding jejunostomyFig. 11.3: Feeding gastrostomyFig. 11.2: Percutaneous endoscopic gastrostomy tube
Section I • Basic Principles of Surgery
42
Manipal Manual of Surgery
Advantages of enteral nutrition:
1. The integrity of gut mucosa depends on provision
of nutrients into the gut lumen. If the fasting period
exceeds more than a few hours, the gut mucosal cells
start disintegrating and the villi get destroyed. This
may permit the intestinal bacteria to enter the
circulation leading to sepsis. Translocation of bacteria
from the intestines into the circulation has been
identified as the ‘motor of multiorgan failure’.
. Use of natural route of nutrition requires less nursing
2
supervision.
3. Infection rate is lower with enteral nutrition.
4. Greater insulin response is seen with enteral
nutrition.
5. There is a lower tendency to retain salt and water.
6. Enteral nutrition is cheaper.
Complications of enteral nutrition: Nausea, vomiting,
abdominal distension and diarrhoea are common.
However, intractable diarrhoea should be investigated
for Clostridium difficile infection. Electrolyte imbalance,
hyperosmolar coma, refeeding syndrome and aspiration
are other problems. M
echanical complications include
tube clogging, displacement, leak and erosion.
Fig. 11.5: Planning of total parenteral nutrition (TPN)
Electrolyte Requirements
The daily requirements of various electrolytes are given
below.
PARENTERAL NUTRITION
When enteral nutrition is not possible for more than a
few days, parenteral nutrition (PN) may need to be
considered. When all nutrition is done by the parenteral
route, it is termed total parenteral nutrition. Partial
parenteral nutrition may be given to supplement
inadequate enteral nutrition.
Parenteral nutrition (PN) to GI failure is like dialysis
to renal failure and ventilator support to respiratory
failure. When enteral feeding is not possible, parenteral
nutrition should be given. Prolonged ileus, intestinal
obstruction, malabsorption, short gut, inflammatory
bowel disease, high output intestinal fistulae are some
common indications for PN (Fig. 11.5).
PN formulations are marketed as:
. Dextrose + amino acid solutions (2 in 1 solution)
1
2. Dextrose + amino acid solution + lipid emulsion
(3 in 1 solution)
• Lipid emulsions are available in 100 to 250 ml bags
or glass bottles and contain the essential fatty acids
that are milky in appearance.
• Insulin is commonly added to PN solutions.
Heparin is occasionally added.
• Vitamins may be added to the solutions. Electrolyte
requirements must be calculated separately on a
Section I • Basic Principles of Surgery
daily basis.
Electrolyte mmol/kg/day
Sodium 1–2
Potassium 1
Calcium 5–10
Magnesium 5–10
Vitamins are given separately. One ampule of watersoluble vitamins must be infused daily, over a period
of time exceeding 30 minutes to avoid urinary loss. Folic
acid, vitamins B
, K, A and D need to be given once a
12
week. Trace elements are given weekly to patients on
long-term PN.
The choice of volume and composition of TPN
solution must be based on the patient’s metabolic
requirement, clinical status and laboratory parameters.
TPN orders should be reviewed each day, so that
changes in electrolytes or acid–base balance can be
addressed appropriately without wasting costly TPN
solutions.
Routes of Administration
. Peripheral vein: Solutions with less than 800 mOsm/L
1
may be administered through a peripheral vein. This
is suitable for short-term PN.
2. Central vein: Either internal jugular or subclavian vein
is cannulated. PN solutions with higher osmolality
must be given through a central vein.
Nutrition in Surgical Patients
43
3. Peripherally inserted central vein catheter: This also
may be used for short-term purposes.
4. Subcutaneously implanted central vein catheter
ports are especially suitable for long-term, domestic
or ambulatory PN.
The central venous access should be dedicated to PN and should
not be used for administration of drugs or other fluids. This line
should be handled with strict asepsis to prevent bacterial growth.
Methods of Administration
The solutions can be gravitated but the rate of infusion
is better controlled, if given through pumps. Smaller
volumes are given initially and is gradually increased
to reach the target volume/day. Absolute aseptic
precautions are observed while handling the catheters
and the PN formulations, since central vein catheter
infection is a dangerous complication. Central vein
catheter should be used exclusively for administering
PN solutions and should not be used for any other
purpose.
Monitoring during PN
Aim
1. To identify excess or deficiency of individual nutrients.
. To identify complications.
2
Daily: Blood sugar, serum electrolytes, blood urea and
serum creatinine.
Biweekly: Liver function tests, coagulation profile,
complete haemogram.
Merits of PN: Assured delivery of nutrients, accurate
and rapid correction of fluid, electrolyte and acid–base
imbalances but it is complicated and expensive.
Complications of PN
. Technical complications: Injury to subclavian/
1
carotid artery, brachial plexus, haemo- or pneumothorax.
2. Catheter-related: Central line sepsis is the most dan-
gerous, at times, life-threatening and yet, preventable
complication and its incidence is a measure of patient
safety. It may not be possible to control sepsis with
antibiotics alone without removing the central
catheter. Thrombosis and catheter clogging are other
problems.
3. Gut mucosal atrophy: Patients on total parenteral
nutrition develop atrophy of the intestinal mucosa
which loses its barrier function and becomes
permeable to bacteria. The consequent bacterial translocation leads to sepsis and multiorgan dysfunction
syndrome (MODS). This is not seen in patients on
partial PN supplemented with EN.
4. Cholestasis: Some patients on long-term TPN
develop cholestasis, jaundice and gallstones which
resolve on starting oral/EN.
5. Fluid, electrolyte and acid–base imbalances are
common.
Section I • Basic Principles of Surgery