Fluid therapy in urinary tract disease Flashcards
Discuss Fluid therapy for urinary disease?
- Despite the many types of kidney disease the underlying principles of fluid and electrolyte management are the same
- Appropriate, well planned fluid therapy is critical to treating most of the patients with urinary tract disease (and so many other conditions…)
Fluid therapy for urinary disease – a recap?
Normal fluid losses = insensible + sensible
What are insensible and sensible losses?
Sensible losses: main one is urine but others include V++, D++, body cavity drainage etc, (burns)
Insensible losses: are those that are not easily measured (resp, panting, sweating etc)
- In the normal healthy animal these are replaced by drinking water and the fluid in food
- In sick animals the fluid therapy needs to be tailored for the individual patient to maintain fluid balance
With renal dz, urine volume is often abnormal (high or low) and so?
Fluid therapy needs to be tailored to each patient.
What is important in assessing fluid deficits?
- A well taken history is very valuable for assessing the extent/duration of the disease e.g number of days its been missing fluid
- A full clinical examination must be performed (and regularly repeated)
- Clinical signs may give an approximation to the degree of fluid deficit
What are the clinical signs associated with differente % of fluid deficits?
How does overhydration appear?
- wet mucous membranes
- increased skin elasticity
- shivering
- nausea
- V++
- restlessness
- serous nasal disch
- chemosis
- tachypnoea
- cough
- dyspnoea
- pulm crackles
- pul oedema
- pleural effusion
- ascites
- D++
- SC oedema etc (hocks intermandibular space)
Patient Assessment?
Assess Perfusion status and Hydration status
Understand what each parameter is an indication of
- Pulse quality. Feel in femoral and dorsal metatarsal.
- CRT
- Heart rate Can be influenced by many other things
- demeanour
- Skin tent gets worse as animals age as they loose collagen
- Blood pressure useful to have serial measurements but cuff itself will elevate BP
- Mucous membranes
- Eye position is the 1/3 eyelid coming over
In monitoring fluid therapy for urinary disease what must you do?
- In addition in small animals, compare dorsal and femoral pulses.
- Also assess capillary refill time
- Weigh the animal twice daily
- In some hospitalised patients it is useful to place a central venous catheter and measure CVP (dogs and cats)
- Assess blood pressure (trends)
- Note fluids offered to patient (e.g 200mls then check later what is gone)
Discuss CVP measurement?
- CVP can give info about intravascular filling, a volume depleted animal will have a CVP less than 0cm H20
- A CVP > 10 cm H20 is consistent with volume overload or congestive heart failure
- Pleural effusion falsely elevates CVP.
Discuss bodyweight measurements and fluid therapy?
•An accurate bodyweight is very valuable. A sick animal may lose up to 0.5-1% of its bodyweight per day because of anorexia, and change in excess of this are caused by changes in fluid status.
Discuss blood pressure monitoring?
- Blood pressure going up may indicate a gain of fluid and vice versa. But high % patients have hypertension, the trend is valuable rather than exact amount.
- 80% dogs with severe acute uraemia have hypertension
- 20-30% cats with CKD have hypertension
Knowing the following parameters will also assist in devising and monitoring the response to a fluid therapy plan?
–Plasma electrolytes
–Packed cell volume (PCV) and total proteins (TPP)
–Lactate values (good value to follow gives us an idea of how effective treatment is. Are we improving perfusion of the organs)
–Acid base status
–(e.g. Equine colic patient on fluids would benefit from serial PCV/TP, Lactate)
–What about Colloid Osmotic Pressure? Device that measures influence of plasma proteins within the blood
Look at this table?
Having assessed the extent of the fluid deficit, the next step is to consider the route for fluid administration. What are these routes?
–Oral
–Rectal
–Subcutaneous (small furries)
–Intraosseous
–Intraperitoneal
–Intravenous
Fluid therapy for urinary disease. What type of fluid is appropriate?
A balanced polyionic solution for initial resuscitation is usual e.g. Hartmann’s (also known as Lactated Ringers Solution –LRS)
What is in Hartmann’s ?
Vetivex® 9 (Ringer’s Solution for Infusion)
Contains: Active substances:
Sodium chloride 0.860% w/v
Potassium chloride 0.030% w/v
Calcium chloride dihydrate 0.033% w/v
Approximate ionic content in millimoles per litre:
Sodium 147 mmol/l
Potassium 4 mmol/l
Calcium 2.25 mmol/l
Chloride 155.5 mmol/l
What is in Vetivex® 1 (Sodium Chloride 0.9 % w/v Intravenous Infusion BP (Vet))?
NaCl
What is in Vetivex® 3 (Sodium Chloride 0.9 % w/v and Glucose 5 % w/v Intravenous Infusion BP (Vet))?
Contains: Active substances:
Sodium chloride 0.9% w/v
Glucose monohydrate 5.5% w/v
(equivalent to anhydrous glucose 5.0% w/v)
Approximate ionic content in millimoles per litre:
Sodium 150 mmol/L
Chloride 150 mmol/L
Each one litre provides approximately 200 kcal.
List isotonic crystalloids:
Isotonic-Lactated Ringer’s solution (LRS) aka Hartmann’s – most common fluid therapy used
- It has a very close constitution to plasma (very alike) with respect to sodium and chloride.
- Na + 130 mEq/l , Cl – 109mEq/l
- Buffered, contains lactate as a bicarbonate precursor
- Inadequate potassium for long term: meaning if an animal is hyperkalaemic- this will not push it over the edge
- Good for shock, diuresis, during anesthesia & can use for maintenance (can add other things to it)
- Low levels of calcium: again if hypercalcaemic, will not push over the edge
- Similar tonicity to plasma
- Of 1 litre administered, 250 ml remains in vascular space
- If in doubt choose Hartmann’s!
Other examples of licensed crystalloids:
NaCl solution- like Hartmann’s but without the electrolytes and lactate
Ringers solution- like Hartmann’s but no lactate
5% glucose- small amounts of glucose
What are colloids?
They are much bigger molecules within the fluid and have the action to expand plasma volume quicker and usually last longer than crystalloids as well.
They support colloid osmotic pressure and are used to support the circulating blood volume when needed e.g. severe hypovolaemia, SIRS (systemic inflammatory response syndrome), haemorrhage, hypoproteinaemia
- Colloids are isotonic but exert a colloid osmotic pressure and may be associated with problems- can be linked with anaphylaxis
- More rapid initial re-expansion of volume
- Support circulation longer than crystalloids
- Types - artificial -oxypolygelatins, dextrans rarely used by V/S in UK, starches, HBOCs, also natural colloids e.g. albumin, plasma etc
What is maintenance rate?
- There are several formulae for calculating maintenance rate
- Most of these formulae assume a normal fluid balance though!
- 2-4ml/kg/hr, or 66ml/kg/d or [30xBW]+70 are some of the commonest formulae (see pic for others)
- Anyway, they are a starting point!
Oliguria – what to do?
- ‘Rehydrate’ the patient
- Then try to determine if the oliguria is pathological or physiological
- If the patient is <5% dehydrated no clinical signs will be evident so give normal looking patients a volume 3-5% of their bodyweight – ‘fluid push’ – if no urine –> its pathological
- Rule out anuria being caused by obstruction or leakage before assuming it is due to renal damage
- Pic: cat with retroflexed bladder.
Discuss Outpatient fluid therapy?
- This can be offered to some owners
- The patient can be injected SC daily or eod, or come to the practice for this
- Devices can be implanted to prevent having to inject the animal
- Cats seem to respond better than dogs to SC fluids?
- LRS or 0.9%NaCl (100-150ml/d or eod)
- Don’t use dextrose
Discuss how to K+ supplement?
–K+ supplementation
–Do not exceed 0.5mEq/kg/hr
