1. Fluid and Electrolyte Balance
FCCNC
5th July 2016

2. Aim To understand the role of fluid and
Thursday, 15 November 2018
Aim
To understand the role of fluid and
electrolytes in the assessment of the
critically ill patient
Jane Roe (Critical Care Modules) January 05

3. Learning outcomes Describe the different body fluid compartments
Understand the role of electrolytes in fluid balance
To gain a basic understanding of the regulation of fluid and electrolytes
Increase awareness of alteration in body fluids & electrolytes caused directly or indirectly by critical illness
Be able to assess fluid and electrolyte balance

4. Normal Body Fluid Distribution

5. Body fluid compartments
Body water accounts for 60% of an adults total body weight
Fluid compartments are separated by cell membranes
Compartments or cell membranes are permeable to water but not all solutes
Plasma membrane
Specialised cell layers
i.e. They have semi-permeable membranes

6. Body fluid Compartments
Intracellular
Extra cellular
Intravascular (plasma)
Interstitial (Tran cellular, extra vascular)

8. Hydrostatic/osmotic pressure

9. Metabolic response to critical illness:
Ebb phase hours
Flow phase – carbohydrate and fat stores are reduced and there is an increase in fluid in the intra and extracellular compartments (Mallett 2013)

10. Third Space Fluid Shift
Increased capillary permeability – integrity and function of capillary membrane lost, consequence of the inflammatory cascade
Albumin losses – Osmotically active molecules are lost
(Mallett 2013)

11. Fluid Volume Deficits Exsanguination
Thursday, 15 November 2018
Exsanguination
Skin - Fever, temp > 38.30C =  500ml
temp > C =  1 000ml
GI disturbances, Vomiting, Diarrheoa, Fistula, Drainage tubes
Lungs respiratory rate > 35bpm,  fluid loss
Urine Polyuria e.g. hyperglycaemia, Diuretics
This results in intravascular hypovolaemia, hypoperfusion, cellular hypoxia, cell membranes dysfunction– resulting in cell death (Mallett 2013)
Jane Roe (Critical Care Modules) January 05

12. BUT………… Injudicious use of fluid can worsen outcome Heart failure
Abdo surgery
ALI
AKI requiring cRRT
Sepsis
(Mallett 2013)

13. Fluid Volume Excess (Oedema)
Thursday, 15 November 2018
Fluid Volume Excess (Oedema)
Abnormal and isotonic retention of water and sodium
Over administration of Na+ containing fluids
Excessive ingestion of salt
Compromised regulatory mechanisms e.g. CCF, renal failure, cirrhosis of liver, steroid excess
Increased capillary HYDROSTATIC pressure
Decreased removal of interstitial fluid
Jane Roe (Critical Care Modules) January 05

14. Fluid Volume Excess (Oedema)
Thursday, 15 November 2018
Fluid Volume Excess (Oedema)
Increased capillary HYDROSTATIC pressure
Volume expansion (colloid or blood transfusions)
Venous obstruction (bed rest, capillary pressure > 32 mmHg, restricts venous return), gravity, standing, pregnancy, PEEP
Increased capillary permeability from
Burns
Allergies
Infection
Jane Roe (Critical Care Modules) January 05

15. Fluid Volume Excess (Oedema)
Thursday, 15 November 2018
Fluid Volume Excess (Oedema)
Decreased removal of interstitial fluid
Obstruction to lymphatic flow e.g.
Tumours
Local oedema
Bruising
Decreased plasma oncotic pressures e.g.
 Hb
 plasma proteins from  capillary permeability
Pernicious anaemia.
Jane Roe (Critical Care Modules) January 05

16. Assessment of Fluid and Electrolytes
Thursday, 15 November 2018
Assessment of Fluid and Electrolytes
Jane Roe (Critical Care Modules) January 05

17. History-taking Pathological process Medication / treatment
Thursday, 15 November 2018
History-taking
Pathological process
Medication / treatment
Abnormal loss of body fluid
Dietary restrictions
Adequate fluid intake
PATHOLOGICAL PROCESS - diabetes, pancreatitis, bowel obstruction
MEDICATION - steroids, diuretics.
How might this interfere with fluid balance?
ABNORMAL FLUID LOSS - stomas, D+V, temperature
DIETARY RESTRCITIONS - low-sodium,
Why have they been imposed?
FLUID INTAKE - fluid restrictions etc
Jane Roe (Critical Care Modules) January 05

18. Inspection / Examination
Thursday, 15 November 2018
Inspection / Examination
Facial appearance
Mucous membranes
Dry mouth
Thirst
Subjective, osmolarity
Tongue Turgor
Longitudinal furrow(s)
Red, swollen = Na+ excess
Filling of neck veins
FACIAL APPEARANCE - fluid volume deficit (FVD) leads to sunken face
severe deficit reduces intraocular pressure - sunken eyes and ‘soft’ feel
MUCOUS MEMBRANES - FVD or hypernatraemia (dry, sticky membranes)
TONGUE TURGOR - FVD, deep longitudinal furrow and shrunken tongue (useful as unlike skin turgor does not alter with age)
THIRST - increase in concentration with osmotically pull fluid from thirst control centre and stimulate thirst (changes of 1 - 2%).
So sensitive that hypernatraemia rarely occurs in patients with normal conscious level
FILLING OF NECK VEINS - visual and CVP.
Jane Roe (Critical Care Modules) January 05

19. Inspection / Examination
Thursday, 15 November 2018
Inspection / Examination
Appearance and temperature of skin
Skin Turgor
Pulmonary oedema
Capillary refill
Neuromuscular instability
Imbalances of calcium, magnesium
SKIN - best measured over the sternum. Should return quickly to normal, measures interstitial volume
OEDEMA - excessive accumulation of interstitial fluid. Not normally apparent until interstitial volume increased by 2-3 litres.
Increased capillary permeability (burns, localized trauma)
increased capillary pressure forcing fluid into interstitial (heart failure)
PULMONARY OEDEMA
CAPILLARY REFILL
NEUROMUSCULAR INSTABILITY - increase (hypocalcaemia, hypomagnesia, hypernatraemia) and vice versa
Jane Roe (Critical Care Modules) January 05

20. Vital signs & Haemodynamics
Thursday, 15 November 2018
Vital signs & Haemodynamics
Body temperature
Pulse (HR and peripheral pulses)
Respirations
Blood pressure
Central Venous Pressure – inc. ScVO2
Urine Volume & Concentration
Body weight
Passive Straight Leg Raising (SLR)
Echo
Flow monitoring – SV, CO, CI, SVV
BODY TEMPERATURE - hypernatraeima: lack of water for sweating causes fever
Fever - increase metabolic rate and need for fluid for renal excretion, also increase RR leads to fluid loss through respiratory system
centigrade increase fluid need by 500mL, over 39.4 by 1L
PULSE - tachycardia: reduction in FVD. Bradycardia: high K+
RESPIRATION - compensatory in acidosis
BLOOD PRESSURE
CVP- A normal value in a spontaneously breathing patient is approximately 5-10cm H2O.
CVP is a measure of the pressure in the right atrium,estimates cardiac function and blood volume.
Jane Roe (Critical Care Modules) January 05

21. Investigations Laboratory results:
Thursday, 15 November 2018
Investigations
Laboratory results:
Trends, U+E’s, Inc. BNP(Brain or Btype Natriuretic Peptide)
Urine testing
Jane Roe (Critical Care Modules) January 05

22. Laboratory results White blood cells Biochemistry
Thursday, 15 November 2018
Laboratory results
White blood cells
Biochemistry
Sodium (Na+) mmol/L
Potassium (K+) mmol/L
Phosphate
Urea – 6.4 mmol/L
Creatinine mmol/L
Albumin 35 – 48 g/L
Haematocrit Male 44-52%
Female 39-47% Hb
Sodium - Regulates body water volumes
Abnormalities reflect water balance disturbance
Elevated plasma glucose pulls out water diluting Na
Potassium – provided by diet. Acidosis (K+ out of cells causing serum level to rise).
Can be cause by tight tourniquet
Urea – waste product of metabolism, excreted by kidneys
Creatinine – retention shows glomerular insufficiency. Specific indicator of kidney malfunction and muscle wasting
Jane Roe (Critical Care Modules) January 05

23. IV fluid therapy Dextrose? N.b not in neuro patients
‘Normal’ Saline? 154mmol/L Na+ and Cl-
Hartmann’s solution – 131 Na+ and 111Cl-
Colloid?
Albumin - ?SAFE study no benefit from Albumin
Starch? 6S study found more harm from starch when compared to Hartmann's in septic adults

24. Fluid Challenges:
Cecconi et al (2015) FENICE study Intensive Care Med 41:1529–1537
? 4ml/kg or 250mls bolus
Which access?
?pressure bag
End point parameters?
Maximum dose?

25. NICE pathways / guidance:
NICE Pathways (2015) Intravenous fluid therapy in adults in hospital
NICE (2013) Intravenous fluid therapy in adults in hospital NICE Clinical Guideline 174

26. Normal Electrolyte Distribution & Function

27. Thursday, 15 November 2018
Electrolytes
A substance that develops an electrical charge when dissolved in water
Dissociates into an ion
Cations electrolytes with a positive charge [Na+ K+ Mg2+]
Anions electrolytes with a negative charge [Cl- HC03-]
The number of cations & anions in any solution or fluid compartment should balance at resting cell membrane potential
Cations and anions are present in equal amounts as positive and negative charges must be equal, an electromechanical fact.
Jane Roe (Critical Care Modules) January 05

28. Electrolyte Function Control cellular activity
Regulator of nervous and metabolic activity
Generate concentration gradients to move ions between intracellular and extracellular compartments

29. Common Electrolytes Na + K + Ca 2+ Mg 2 + Phosphate2-
Thursday, 15 November 2018
Common Electrolytes
Na +
K +
Ca 2+
Mg 2 +
Phosphate2-
Jane Roe (Critical Care Modules) January 05

30. References:
Mallett, Albarran and Richardson (2013) Critical Care Manual of Clinical Procedures and Competencies. Wiley. West Sussex.
Perner et al (2012) 6S study NEJM 367 p
Safe study investigators (2004) A comparison of albumin and saline for fluid resuscitation in the intensive care unit. NEJM 350 (2) p

31. Any questions?