Introduction
With the advancement in the diagnosis and treatment
of various diseases, leading to a better life expectancy, we
have a surge in the number of patients in the geriatric age
seeking medical advise for acute and preexisting chronic
conditions. When it comes to geriatric age, apart from
pharmacotherapy, there is a need for an enhanced psychosocial,
social and rehabilitative care [1].
These patients often have significant loss in the muscle mass
due to undernutrition. When such a patient ends up in the
intensive care unit, the management becomes all the more
challenging. The incidence of malnutrition among these
patients has been evaluated to be in the range of 38%-100%
among patients requiring mechanical ventilation and 20-35%
among hospitalised patients as a whole. Coexistent
malnutrition among the elderly has been found to be in the
range of 30-40% attributable to chewing difficulties, lack of
appetite, economic and physical dependence, etc [7]. This
easily translates into increased hospital stays, delayed wound
healing, increased infections and increased mortality rates
[2].
Hence a carefully instituted nutritional support in the
intensive care for these patients which includes a
comprehensive assessment as per the body needs and early risk
assessment with a multidisciplinary approach should be ensued
for a smooth clinical recovery.
Nutrition therapy - why is it needed?
This the most basic question to be answered before initiating
nutrition therapy. A basic nutrition plan is to prevent and
treat malnutrition among patients who are unable to sustain an
adequate oral intake.
This definition goes hand in glove with a proper evaluation
process for assessing the severity of malnutrition, severity
of the disease process and expected duration of recovery and
preexisting comorbidities.
Nutrition screening and assessment
Nutritional status assessment of the critically ill patient is
performed to classify nutritional status, identify nutritional
risk, and to serve as a baseline for monitoring nutrition
support adequacy. Most of the nutritional screening tools
being used in geriatric age group are validated for outpatient
and inpatient scenarios and very less specific tools are
available for implementation in a critically ill geriatric
patient.
A complete nutritional history taken from the family
members, recent history of any unintentional weight loss in
the preceding 4-6 months of ICU admission gives a fair idea
about the nutritional history of the patient. The American
society of parenteral and enteral nutrition (ASPEN) 2016
guidelines recommend nutritional risk screening 2002 and
NUTRIC score for a critically ill patient [5]. But
scores like MUST (Malnutrition Universal Screening Tool) and
GNRI (Geriatric Nutritional Risk Index) has been found to be
more sensitive in identifying malnourished geriatric patients
[4].
The predictive validity of MUST scoring for the length of stay
in hospital and mortality prediction in elderly patients
including the ability to screen all the elderly patients has
been demonstrated [4]. The Geriatric Nutrition Risk Index
(GNRI), replaces the original formula of ideal weight patients
(LORENT’s formula) to be applied in geriatric age group adding
serum albumin and ratio of current weight and ideal weight of
the individual [4]. Though there are multiple screening tools,
resource constraints specific to an Indian critical care unit
with shortage of dieticians and an overburdened critical care
specialist makes a perfect nutritional screening and
assessment difficult to be done for all the patients [5]. It
is imperative that a nutritional assessment should be done by
a qualified and trained nutritionist dedicated to ICU with
good coordination between the intensivist and the
nutritionist.
Nutritional supplementation
Muscle mass preservation, especially in a geriatric
patient in the ICU patient is most important. The entire
nutrition plan depends upon the diagnosis, severity of the
illness, the present nutritional status and the clinical
outcome depends upon the components in the nutritional plan
and the route of feeding. The existing literature suggests
weight based equations for calculating the energy protein
requirements. Recommendations are bound to change for obese
patients as well. Keeping a balance in the feeding plan is
very important as underfeeding and overfeeding is detrimental
and impacts the clinical outcome. Hyperacapnia and
refeeding syndrome are often found in overfed patients
and negative energy balance is seen in an underfed patient. At
least meeting 80% of the prescribed caloric intake is
essential for a good clinical outcome [6].
Fluid requirement: Calculation
of nutritional requirement is proceeded by an
assessment of total fluid requirement in 24 hrs which is
around 30-40 ml/kg/day, with extra fluid to compensate for any
overt losses and at the same time a restricted fluid intake in
the presence of significant comorbid conditions like heart
failure or chronic kidney diease [1].
Calorie: A caloric intake of
25-30kcal/kg body weight/day has been recommended which may be
individually adjusted with respect to the disease status, and
tolerance [3,5]. With increasing age, the resting energy
expenditure (REE) comes down due to decreasing fat free body
mass. It was found that in healthy and sick older persona, the
REE measurement gave a value of 20kcal/kg/day. And when a
patient becomes sick, the energy requirements one hand may be
reduced due to reduced physical activity and on the other hand
may be increased due to disease effects like
inflammation, fever, and drug metabolism etc. There is a great
heterogeneity and inter-individual variation of the energy
requirements and hence close watch on the body weight
along with the water retention and losses etc should be taken
into consideration with a day to day assessment. It should be
kept in mind that the spontaneous oral intake of a geriatric
patient in ICU will never cover the requirement [3].
Protein: 1.2-1.5 g/kg body weight/day has been
recommended in acute or chronic illness with an escalation to
up to 2g/kg body weight in case of a much severe illness or
preexisting malnutrition [3]. It should also be kept in mind
that an insufficient intake of calories increases the protein
requirement and hence a balance needs to be maintained
with regard to the calorie and protein prescription.
Fats: Fats should provide about 20-50% of the
total energy requirements which should also consist of
essential fatty acids.
Micronutrients and electrolytes: They also form
an important component of a balanced dietary prescription,
recommendations don’t differ from that of a younger adult.
Owing to increased prevalence of gastrointestinal diseases
among elderly, these patients are more prone for micronutrient
deficiencies and hence appropriate supplementation should be
done [3] .
Route and dosage
The most important aspect of nutritional support
after prescription is the route of administration. The route
of nutritional delivery determines the effect of nutritional
intervention. The available options being:
a. Enteral nutrition (EN)
b. Parenteral nutrition (PN)
Enteral nutrition
A more physiological route when compared to parenteral
nutrition. Enteral nutrition is associated with far lesser
complications when compared to parenteral route. The low
incidence of infectious complications and low cost with wide
variation in the supplemental formulations makes it the ideal
route in a critically ill patient who is able to tolerate it.
The same may be difficult in conditions of intestinal
obstruction, peritonitis, bowel ischaemia, etc. Though studies
have shown a differential effect on mortality, the most
consistent advantage is the reduction in the infectious
complications. Early initiation of enteral nutrition (24-48
hrs) has proven to decrease the infectious morbidity and
length of hospital stay. Enteral nutrition can be
administered through various routes like nasogastric,
nasoduodenal tubes or by a nasojejunal route for a short term
basis (4-6 weeks) and in scenarios of long term requirement
can be administered through feeding gastrostomy, feeding
jejunostomy [7].
Practical considerations of enteral nutrition
1. It is recommended to initiate EN early (24-48 hrs) as it
has been found that delaying feeding has been associated with
an increased incidence of gut permeability and release of pro
inflammatory mediators [5].
2. A minimum target of 50-65% of the goal calories
should be ensued in 48-72 hrs of initiation of feeds.
3. If unable to meet the energy requirements after 7-10 days
of EN alone, initiation of supplemental PN should be
considered keeping in mind the detrimental effects of PN like
infections, dyselectrolemia, hyperglycemia, etc.
4. Permissible underfeeding, not routinely recommended can be
initiated in critically ill obese with a BMI> 30 in
certain circumstances. This may add some benefit to the
metabolic outcomes and decrease the length of ICU stay. But it
has been found that, under prescription by physicians itself
leads to underfeeding. ESPEN 2018 guidelines on clinical
nutrition and hydration in geriatrics don’t recommend
weight reducing diets in overweight older persons [3,5].
5. If the patient is deteriorating hemodynamically, with an
increasing vasopressor requirement, EN should be withheld
until patient is stable as it is known to precipitate bowel
ischemia/reperfusion injury involving intestinal
microcirculation [7].
6. Always, tolerance to EN should be monitored. As per the
ASPEN (American Society of Parenteral and Enteral Nutrition)
guidelines 2016, upto 500 ml of gastric residual volume (GRV)
should be used as cutoff. In case any signs of intolerance
like abdominal pain, distension, non passage of flatus along
with high GRV, taking into account the multiplicity of these
signs and not just any one sign, EN may be withheld. Nurses
should be trained to look for signs of intolerance. However in
Indian ICUs there is a marked difference of opinion regarding
the cutoff values of GRV and there is no standard guideline.
Hence keeping this in mind, it is recommended that GRV
monitoring should be assessed every 6-8 hrly and cutoff range
be kept between 300-500 ml. But in patients who are on
continuous tube feeding, frequent GRV monitoring may not be
required. Prokinetics like metoclopramide and erythromycin may
be used in intolerance and risk of aspiration [5].
7. Diarrhoea in EN should raise the suspicion for non
infectious ethology like use of hyperosmolar feeds or
medications like broad spectrum antibiotics, etc and
infectious cause like clostridium difficle pseudomembranous
colitis, etc. Shifting to elemental diet preparations should
be done along with anti motility agents if infectious ethology
is ruled out.
8. Preexisting micronutrient deficiency should be assessed and
supplemented accordingly.
Selecting the best enteral formula: The
composition of EN formula has got a wide variability and
prescription of the same should be done keeping in mind the
balance between macro and micronutrients. On a routine basis,
in dietary, a blenderized tube feeding formula is prepared by
mixing either kitchen food or kitchen food plus standard
formula into a liquid consistency. But the drawback of this is
a propensity for a high microbial contamination, underdelivery
of nutrients, high osmolality and viscosity leading to
blockade of feeding tubes. Hence a standard formula feed would
be a better option when EN is initiated, though a strict
practice of the same is rarely done in all Indian ICUs.
A better perspective about disease specific feeds and organ
failure specific feeds has been reviewed in a Indian scenario
by Mehta Y et al in 2018 [5].
Parenteral nutrition (PN) [3,5,7]
A safe and effective therapeutic modality for delivering the
necessary calorie, macronutrient and micronutrients via a
central venous line or a peripheral venous line. Several
studies have documented that PN is an effective and practical
nutritional support choice in older patients as well. The
indication criteria for PN remains the same as in a middle
aged individual: facing a period of starvation for more than 3
days when oral or EN is impossible and when oral feed or EN
has remained insufficient to meet the demands for 7-10 days of
initiation of EN [3].
Such patients should not be physically restrained nor
any pharmacological sedation given for administering either EN
or PN. In conditions like incurable disease, malignancy with
imminent death within the next four weeks, initiation of PN
should be done only if it is is going to bring a major change
in the patients condition as patient comfort should be given
prime importance in such scenarios [3].
Practical considerations:
1. In older patients with malnutrition, there has been an
increased incidence of trace elements deficiency. Hence these
should be incorporated in the parenteral formulation.
2. Elderly patients usually have coexisting renal issues and
cardiac illness and hence a limited fluid intake and sodium
restriction should be done to avoid a fluid overload.
3. The overall incidence of a blood stream infection in
patients on PN goes up by 30% which is irrespective of age,
hence a high caution needs to be maintained.
4. There is an increased propensity for hyperglycemia in
elderly which may be due to insulin resistance and lower
glucose oxidation.
5. Increased incidence of dyselectrolemia especially,
hypokalaemia and hypophosphatemia, which needs to be closely
monitored.
6.
Refeeding syndrome: A life threatening
complication, seen especially in chronically starved older
patient in whom PN is initiated. Acute metabolic perturbations
like hypophosphatemia, hypokalaemia, hypomagnesemia are
seen which may lead to acute pulmonary oedema, arrhythmias and
ventilator dependency. Hence feeding such patients should
involve a step up plan starting with a low intake which should
be gradually escalated over 7-10 days.
Conclusion
Nutrition in intensive care unit is proven to bring in a lot
of modification in the patient outcomes. Critically ill
elderly patients are usually hyper catabolic with a volatile
nutrient requirement. An optimal nutritional therapy not only
helps in catering to their increased metabolic demand, but
also alters the course of recovery from a critical state. But
a patient tailored optimal nutrition therapy in an elderly
person is a real challenge and needs a good team work
between the physician, intensivist and the nutritionist. A
good clinical judgement is required in identifying those
elderly who are more likely to benefit from a structured
nutritional intervention.
References
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