fluids and nutrition in the icu

Fluids and Nutrition in the ICU

Dr Paul HealeyJohn Hunter Hospital, Newcastle

August 2013

Bigger than Ben Hur !!

Outline• Fluids and electrolytes

– Basic physiology– Assessment of fluid status and fluid responsiveness– Fluids - Crystalloids and Colloids– Fluids - Costs– Evidence to guide fluid delivery– Case studies

• Nutrition– Why is nutrition important in ICU patients– Enteral nutrition– Parenteral nutrition– Evidence for nutritional choices– Feed intolerance– Diarrhoea

• The refeeding syndrome

Why fluid therapy• 2nd most common medical therapy• Often prescribed by the most junior member of medical

team• There is often confusion as to what end points to aim for

with fluid therapy– BP– HR– UO– CVP– Derived numbers such as SVV, VTI, PPV

• Fluid prescription is mostly dependent upon your postcode.

Historical perspective

• 1832 – Cholera patient in Scotland who was critically ill and dehydrated given saline based solution instead of blood letting which was standard of care for the time

• 1876 – Development of Ringer’s solution by Sidney Ringer in London

• 1876 – Modification of Ringer’s solution to include lactate by Dr Alex Hartmann in the US

• 1940 – Use of albumin by US army in WWII• 1950 – Development of the plastic catheter by Mayo

Clinic Anaesthesiology resident Dr David Massa, which allowed widespread use of IV fluid therapy, despite the lack of any evidence of its potential efficacy

Some basics

• Water • Electrolytes

Physiology - Water

Physiology - electrolytes

Daily fluid and electrolyte requirements - Physiology

Physiology - electrolytes

Pathophysiology

• Traditional model – Starling model

Pathophysiology• Revised model in pathology of critical illness• Importance of the endothelial surface layer (glycocalyx) in transvascular

exchange• When ESL in tact and in euvolemia – colloids may sustain plasma expansion

better.• However in critical illness with inflammatory degradation of the ESL that

causes increased vascular permeablity there is increased trans-capillary escape of albumin and other colloids, which may explain their diminished benefit

• In the major trials comparing colloid to crystalloid the ratio of dose was 1: 1.2-1.4, not 1:3 as was predicted

• The increased transcapillary leak will also allow excess crystalloid to accumulate in the interstitial spaces and contribute to reduced organ function

Phases of resuscitation• 1. Acute resuscitation

– Goal is restoration of effective intravascular volume, organ perfusion and tissue oxygenation

– Fluid accumulation and a positive fluid balance• 2. Maintenance

– Goal is maintenance of the intravascular volume– Prevent unnecessary fluid loading and mitigate fluid accumulation

• 3. Fluid removal– Goal is ‘active de-escalation’ with fluid removal– Secondary organ injury may result from failure to remove

unnecessary volume

Case 1• 75 year old female with septic shock likely secondary to urosepsis, retrieved from Belmont

Hospital• Background

– OA of knees– Ex-smoker 20 years ago

• Management– CTKUB – NAD– 3.5 L of Normal saline– IV metaraminol at 20mL/hr

• Current observations– HR - 120– BP 65/35 – SaO2 96% on 4L via np– ABG – pH 7.15, PaCO2 31mmHg, PaO2 85mmHg, BE -7mmol.L, Lactate 4.5mmol.L

• How can I tell if she needs more fluid ??• If she does need more fluid – which one do I give, and how much ??

How to assess fluid status and fluid responsiveness

• History– Illness history – Comorbidities– Treatment to now – fluid, vasopressors

• Examination– Peripheral temperature– Vital signs (HR, BP, RR, capillary refill) – JVP, pulmonary oedema– Signs of end-organ hypoperfusion

• Decreased LOC• Myocardial ischaemia• Decreased U/O

• Investigations– Pathology (FBC, UEC, LFTs)– ABG – pH, BE, lactate– ScvO2

• Other tests• Static variables

– CVP– PCWP– Echocardiography – IVC diameter and collapse, LVEDA

• Dynamic variables– Passive leg raise– Systolic Pressure Variation/Pulse Pressure Variation – arterial pressure waveform– Stroke volume variation – PiCCO– Echocardiography – cardiac output measures

• Clinical studies have suggested that only 50% of haemodynamically unstable critically ill patients are fluid responsive.

Goals of resuscitation• HR < 100• Normal RR and gas exchange• MAP >65mmHg (may need to be higher in patients with a history of hypertension)• CVP 8-12 mmHg or 12-15 mmHg if intubated• Urine output : 0.5ml/kg/hr• Resolution of end-organ hypoperfuion :

– Improving LOC– Lactate clearance of 10%– Lactate level < 2.0 mmol/L

• ScvO2 >70%• Echocardiography

– Filling state – IVC diameter and collapsability– Ventricular filling– Cardiac output

Case 1• 75 year old female with septic shock likely secondary to urosepsis, retrieved from

Belmont Hospital• Background





What fluid to give ??

The evidence

The SAFE-TRIPS study• Cross sectional study of 391 ICUs in 25 countries to describe

the types of fluids administered during fluid resuscitation. • Data collected in 2007 and published in 2010.• Findings in a 24 hour period:

– 37.1% of patients received resuscitation fluid– Main indicators for administering crystalloid or colloid were

impaired perfusion (45%) or to correct abnormal vital signs (35%)• Overall

– colloid given to more patients than crystalloids (23 vs 15%) and – Colloid given in more episodes than crystalloid (48 vs 33%)

• The choice of fluid was most strongly related to location of the prescriber

Crystalloids

Colloids

• Albumin • Semi-synthetic colloids

Fluids - costs

• Normal saline (1 L)• Hartman’s (1L)• Plasmalyte (1L)• Voluven (500mL)• Albumin 4% (100mL)• Albumin 20% (500mL)• Packed Red Cells (1 U)

• $1.15• $1.20• $2.40• $11.60• $65• $65• $345

Fluids : The evidence

Colloids - Albumin• Albumin is a plasma protein with an average MW of 66kDa. In

healthy humans it accounts for 80% of colloid oncotic pressure. • It has been available for human use since the 1940s.• Albumin is prepared by either cold ethanol (Cohn) fractionation

or chromatographic purification of pooled donor plasma.• It is heat-treated at 60 C for 10 h and incubated at low pH to

inactivate potentially transmissible viruses.• When infused in well hydrated individuals,

– 4% albumin will expand the plasma volume by an amount equal to the volume infused,

– 20% albumin will expand the plasma volume by approximately 4-5 times.

The SAFE trial (2004)• The Saline versus Albumin Fluid Evaluation Study• An international multi-cente RCT of 6997 patients

comparing the use of albumin vs NS for fluid resuscitaton in ICU

• Conclusions– No difference in 28 day mortality– Possible improved outcome with albumin in severe sepsis :

unadjusted RR 0.87 (0.74-1.02), adjusted RR 0.71 (0.52-0.97)– Possible worse outcomes with albumin in TBI with an increased

risk of mortality at 2 years : RR 1.88 (1.31-2.70)• ?? ALBIOS trial (20% albumin)

Cochrane Review : Albumin

The CHEST trial• The Crystlalloid versus Hydroxyethyl Starch Trial (Myburgh et

al 2012)• Involved 7000 general ICU patients who were randomized to

masked fluid resuscitation with either HES 130/0.4 (Voluven) or normal saline while in the ICU

The 6S trial

• Scandinavian Starch for Severe Sepsis/Septic Shock Trial• This trial randomised 804 patients in the ICU with severe

sepsis to resuscitation with HES 130/0.42 (Tetraspan) vs. Ringer’s acetate

Cochrane review – Colloids (2013)

Other controversies

• Fluid balance and mortality• Chloride and organ function • Sodium balance• Normal saline vs buffered crystalloid solutions• No fluids

Fluid balance• In experimental models of porcine septic shock, more vigorous

fluid resuscitation was associated with greater hemodynamic stability, urine output, and preserved RBF; however, despite this apparent physiological benefit, high-volume resuscitation was associated with substantially increased mortality

• The majority of human data is post-hoc associative and not causative – however there appears to be a trend (See table)– Increased mortality– Worse respiratory function– Worse renal fuction– Increased LOS

Fluids : The Chloride problem• Fluid resuscitation with Normal saline causes hyperchloraemic metabolic

acidosis• Shaw et al (2012) Retrospectively reviewed a large clinical database of

major abdominal surgical patients treated only with NS vs only Plasmalyte (30,994 in 0.9% saline arm vs 926 in Plasma-Lyte arm). They found after propensity matching, the 0.9% saline group had: – More fluid (1976 ml vs 1658 ml, p <0.001)– More buffer orders (6.3% vs 4.2%, p = 0.02)– Moretransfusions(11.5%vs1.8%,p<0.001)– Increased ventilator days (3.0 days vs 2.5 days, p <0.001)– A 5-fold greater chance of receiving dialysis (1% vs 4.8%, p <0.001) – But the balanced group had longer length of stay in the hospital (6.4 days vs

5.9, p < 0.001) • Yunos et al (2012) conducted a before after trial of 1533 patients in one

Australian ICU. This involved comparison of a chloride liberal vs a chloride restrictive approach to IV fluid therapy.

Fluids : The Sodium problem• Recommended daily intake = 1 mmol/kg• Point prevalence study across 40 ICUS including 356 patients demonstrated the

median total sodium administered was 225 mmol (IQR of 145-368 mmol) (Bihari et al 2012)

• A recent small study of ICU patients (Bihari et al 2013) demonstrated that sodium balance can be independent of fluid balance. After 5 days of mechanical ventilation:– Cummulative fluid balance = -954mL– Estimated cummulative sodium balance = 258 mmol– Serum sodium increased from 140 to 147 mmol/L– Body weight decreased by -2.7 kg (SD 1.4 kg)– TBW decreased by – 3.4 L (SD 1.4 kg)

• They postulated that sodium balance may correlate better with increased ECF volume and respiratory dysfunction

• Therefore future studies may have to examine sodium balance and morbidity in critical care patients

Cochrane Review : Buffered vs non-buffered fluids

• 14 trials with 706 patients• Included trials of perioperative resuscitation• Excluded trials of colloids, hypertonic fluids and dextrose based fluids• Outcomes• Clinical

– Mortality – no statistical difference– Renal function – no statistical difference– Renal replacement therapy – no statistical difference– Post operative nausea and vomitting – no statistical difference– Blood loss – no statistical difference– Red cell and plasma transfusion – no statistical difference– Platelet transfusion – increased in non-buffered fluid group

• Metabolic– pH – lower in buffered group by mean of 0.06 (0.04-0.08). This was not maintained on postoperative day 1– PaCO2 – higher in buffered group post op (1.2mmHg) and day 1 (3.3mmHg)– Base excess – mean difference of 3.5 mmol/L postoperatively and 2.5mmol/l on day 1– Serum sodium – higher post operatively in non-buffered by 2.7 mmol/L, no difference on day 1 post

operatively – Serum chloride – higher post operatively in non buffered group 114 vs 107 mmol/l, and on day 1

postoperatively (116 vs 107 mmol/L)

No fluid ??

The conclusions• Fluid is a drug, it should be given in appropriate doses, and its use

reviewed regularly. In sicker patients its likely that the timing of the dosage is more important

• There are 3 phases of resuscitation Resuscitation, Maintenance and Fluid removal – identify where your patient lies and act appropriately

• Fluid status and fluid responsiveness is difficult to assess. No one single tool is infallible.

• If unsure – fluid bolus 20mL/kg and reassess. But don’t keep giving if no change.

• Normal saline is the safe answer• Colloids don’t offer any advantage over crystalloids. • Hopefully more directed research the controversies in the future

Nutrition in ICU

Why nutrition is important• Critical illness causes an increase in Basal Metabolic Rate by more than 40%• Chronic malnutrition is a common finding in patients admitted to ICU• The predominant pattern of protein catabolism, resulting in skeletal muscle

breakdown. This includes such important muscle groups as the diaphragm• The loss of lean body mass (whole body water and protein) ranges from 0.5-

1% per day, and is far greater than that from bed rest alone. This can lead to a reduction in muscle fibre cross sectional area of up to 3-4% per day.

• In the early phases of critical illness, only skeletal muscle is effected. However if protracted beyond 2 weeks this can effect the cardiac muscle.

• Providing adequate nutritional intake in the ICU patient can be a challenge:– Delay in initiation– Difficulty reaching target rates of feeding– Fasting for various procedures– Feed intolerance– Diarrhoea

Some basics

Daily requirements

• Energy• 20 – 25 kcal/kg• Protein• 1-2 g/kg• Carbohydrate• 4 g/kg• Fat• 1 g/kg

Case 2• 67 year old male admitted to the ICU following a laparotomy for anastamotic leak, 3 days

post elective hemicolectomy.• Past History

– Bowel Ca on colonoscopy 3 months ago. Normal diet up to operation, no weight loss.– Ex smoker 15 years ago– IHD – AMI 5 years ago

• Currently – Intubated and ventilated– Noradrenaline SS at 15 mL per hour– HR 95, BP 100/60, SaO2 98% on FiO2 50%– Has had 3L of Hartmann’s intraoperatively

• Last ABG – pH 7.2– PCO2 34mmHg– BE -4.5mmol.L– Lactate 2.1

• How are you going to manage his feeding ??

Guidelines for nutritional support

• ESPEN – European Society for Enteral and Parenteral Nutrition (2006)

• Canadian Clinical Practice Guidelines (Updated online regularly – criticalcarenutrition.com)

• American Dietetics Association evidenced based guidelines for critical illness (2009)

• Society of Critical Care Medicine and American Society of Parenteral and Enteral Nutrition’s joint guideline (2009)

Assessment of the patients nutritional status

• History – Duration of illness– Likely ongoing hypermetabolic state– Nature of illness– Recent weight loss– Co-morbid disease – Liver, Kidney, GIT, Cancer

• Examination– Assessment of metabolic activity (Arousal, vital signs)– Muscle wasting– Signs of micronutrient deficiency (angular stomatitis, glossitis, pale conjunctiva, skin, hair, nails)

• Investigation– Pathology

• Haemoglobin, Iron stores• Electrolytes• Albumin or Pre-Albumin• Transferrin, Coagulation• Fat soluble vitamin levels• Water soluble vitamin levels

– Subjective Global Assessment– Indirect calorimetry– Anthropomorphic measures (mid-arm muscle circumference, skin folds)

• Consultation– Dietician– Equations to estimate daily energy requirements (Schofield, Harris-Benedict)

Early enteral nutrition• On admission all patients should be assessed for feeding via enteral

nutrition. • Exceptions

– Tolerating adequate oral diet– <24 hours to oral intake– Palliative care

• There are a number of patient groups who are unable to be fed enterally– Bowel obstruction– Ischaemic bowel– Imminent bowel resection– Enteric anastamosis– Enteric fistula– Severe exacerbation of inflammatory bowel disease

Early enteral nutrition• Guidelines

– Enteral nutrition should be started in the first 24-48 hours of admission following resuscitation

– There is evidence of a possible reduction in treatment time, hospital LOS and infectious complications, compared with delayed EN

– Aim to reach 60% of target EN by 5-7 days• ACCEPT trial (Martin et al 2004)

– Implementation of a feeding algorithm resulted in increased delivery of nutrition, reduced hospital LOS, and trend to decreased mortality

– Clinical outcomes not replicated in later ANZ trial• EDEN trial (Rice et al 2012)

– Initial trophic feeds vs full enteral nutrition for the first 6 days in 1000 patients with acute lung injury

– No difference in 60 day mortality, ICU LOS, ventilator-free days and infectious complications

– The full feeding group had higher use of prokinetic agents, higher rates of feed intolerance, more constipation and more vomitting. They also had higher BSLs and more insulin use.

Total Parenteral Nutrition• Involves the provision of complete nutrition via CVC in patients who are unable to tolerate enteral nutrition• Requires the provision of macronutrients, micronutrients and fluid• Indications• General

– EN contraindicated– EN fails to meet nutritional requirements

• Specific– prolonged bowel obstruction and ileus– short bowel syndrome with severe malabsorption– severe dysmotility– high output intestinal fistulae– anastomotic break down– intolerance to EN

• Advantages– Provides nutrition to those patients who are unable to tolerate EN

• Disadvantages– Cost– CVC access – requires dedicated lumen– Hyperglycaemia– ? Infection– Loss of GIT structure and function– Stress ulceration

TPN : Guidelines• Guidelines• There is disagreement between guidelines on commencement of PN in critically ill

patients• If patients well nourished

– European guidelines recommend early (24-48hrs) commencement of PN if patients unlikely to reach EN targets at 3 days

– American guidelines recommmend late (7 days) commencement of PN if patient unlikely to reach EN targets, and suggest only use if likely to require for longer than 5-7 days

– Canadian guideline recommends against early PN and high dose IV dextrose, and states that timing of PN to be individualised to each patient

• If patient malnourished– All guidelines recommend early commencement of PN if patient unlikely to reach EN

targets, assessed on a case-by-case basis• All recommend only feeding patients up to the desired intake (20-25 kcal/kg/day)• All recommend regular reassessment of the patients need for PN, and cease when

patient is tolerating 60% of desired intake via enteral route

TPN : recent trials

• EPANIC trial (2011)

Early PN trial

• Early PN trial (2013)

Nutrition – costs

• EN - $5 per bag (2 bags per day) • TPN – Approx $250 per bag (1 bag per day)– Feed– Pharmacy compounding– Delivery

Case 2• 67 year old male admitted to the ICU following a laparotomy for anastamotic leak, 3 days post

elective hemicolectomy.• Past History

– Bowel Ca on colonoscopy 3 months ago. Normal diet up to operation, no weight loss.– Ex smoker 15 years ago– IHD – AMI 5 years ago

• Currently – Intubated and ventilated– Noradrenaline SS at 15 mL per hour– HR 95, BP 100/60, SaO2 98% on FiO2 50%– Has had 3L of Hartmann’s intraoperatively

• Last ABG – pH 7.2– PCO2 34mmHg– BE -4.5mmol.L– Lactate 2.1

• How are you going to manage his feeding ??• Does this patient need TPN ??

Feed intolerance

Possible causes of feed intolerance

• -> NG not in correct position• -> intra-abdominal pathology• -> opioids• -> interruptions of feed for procedures/OT• -> gastric paresis• -> ileus• -> sepsis• -> electrolyte abnormalities

Feed intolerance : treatments• Gastric residual volumes (GRVs)• Guidelines

– Optional monitoring of GRVs– Suggest 250-500mL as the limit for possible feed intolerance

• GRV monitoring trial : Reignier et al 2013– Open label RCT of 452 patients in 9 French ICUs comparing no GRV monitoring to 6

hourly monitoring with a 250mL limit– No difference in VAP, acquired infections, duration of MV, ICU LOS or mortality rates– Proportion of patients receiving their full calorie goal was higher in no monitoring

group, and rates of vomitting higher• Prokinetic agents• Guidelines

– Should not be used routinely– Evidence suggests that when used in a feeding algorithm for feed intolerance, it may

improve clinical outcomes, and does improve feed tolerance, gastric emptying and EN delivery

– Metoclopramide should be the first choice. Small number of trials that show less feed intolerance with dual therapy

Feed intolerance : treatments• Post pyloric feeding • Guidelines

– Should be considered if easy access to bedside insertion– Consider in patients on heavy sedation, nursed supine or evidence of feed

intolerance with high gastric aspirates.• Meta-analysis : Zhang et al (2013)

– No benefit in terms of mortality, new-onset pneumonia or aspiration– PPF delivers higher proportions of estimated energy : WMD 12% (5-18%),

and reduce GRV : WMD -170mL (-290 to -46mL)• ENTERIC trial : Davies et al (2012)

– Compared early PPF with gastric feeding in 181 ICU patients– Demonstrated no difference in caloric intake, mortality, VAP, vomitting or

diarrhoea.

Diarrhoea management• Diarrhoea is common in ICU • Prevalence is approximately 40-70% depending on definition• It results in

– patient discomfort, – Reduced nutrition– electrolyte and fluid disturbances, – increased nursing work, – wound contamination– skin excoriation

• The causal factor may be obvious– Infectious diarrhoea – eg Rotovirus, salmonella, campylobacter– Clostridium difficile– GIT disease and surgery– Faecal impaction

• Most often the cause is multifactorial– Enteral feeds– Laxatives– Medications– Electrolytes

Refeeding syndrome• Defined as the potentially fatal shifts in fluids and electrolytes that may occur in

malnourished patients receiving artificial refeeding, whether enterally or parenterally

• The hallmark biochemical feature of refeeding syndrome is hypophosphataemia.• However, the syndrome is complex and may also feature

– abnormal sodium and fluid balance; – changes in glucose, protein, and fat metabolism; – thiamine deficiency;– hypokalaemia;– hypomagnesaemia

• With the restoration of glucose as a substrate, insulin levels rise and cause cellular uptake of ions.

• Depletion of intracellular ATP and 2,3 DPG results in tissue hypoxia and failure of cellular energy metabolism

• Manifestatiosn include– Cardiac and respiratory failure– Seizures and paraesthesias

Refeeding syndrome - risk

Refeeding syndrome - management

Conclusions• Start feeding early in appropriate patients• Assess risk of refeeding syndrome, check daily and increase feeds

slowly. Supplement with thiamine and multi-vitamin• Refer to dieticians – and read their input• Parenteral nutrition

– Liase with treating team, intensivist, dietician and pharmacist– Consider if patient cannot use enteral route, is severely malnourished or

not tolerating enteral feeds after 5-7 days• DON’T stop feeds for intolerance, assess patients, use prokinetics

and continue feeds• Diarrhoea is common. Exclude the common causes, remove

potential contributors and treat consequences

References

• Many days and nights of fun in the ICU

fluids and nutrition in the icu

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