Fluids

Question 1

Fluid therapy

Answer 1

 Maintain body water (patient can’t drink)
 Replace body water (patient is dehydrated/bleeding)
 Maintain blood pressure (anesthesia, shock, …)
 Diuresis (toxins, overdose)
 Other
 Vehicle to deliver drugs
 Electrolyte correction
 Parenteral nutrition
 Blood or blood product transfusion

Question 2

Per os fluid administration

Answer 2

 Drinking
 Preferred
 Largest volumes
 Closest to nature
 Limitations
 Works if mild dehydration
 Patient must be conscious
 No vomit – Will make it worse
 No diarrhea – Won’t absorb

Question 3

Iv fluids

Answer 3

 Fastest
 Large volume
 Status of patient does not matter
 Only choice if severely dehydrated, shock
 Can use to deliver drugs, electrolytes, nutrition
 Limitations
 High cost, technical
 Hospitalized
 Requires venous access

Question 4

Subcutaneous fluids

Answer 4

 Under the skin
 Most common in small animals –> Cats
 Volume is limited by skin physiology
 Cats have less SQ attachment so more room
 Dogs have more attachment so less room
 Practical, fast, lower cost

Question 5

Administering SQ fluids

Answer 5

 Aseptic technique
 Alcohol swab injection port on IV bag
 Discard needles after each use
 Generally only 0.9% NaCl or lactated ringers (LRS)
 Maximum volume is 100 ml/day cat
 Give 50 ml twice; or split into 2 (or more) sites once

Question 6

Intraosseous fluids

Answer 6

 Into the medullary canal of a long/large bone
 Tibial tuberosity, trochanteric fossa of the femur, wing of ilium, greater tubercle
 Most common in exotics and neonates
 Technical
 Requires aseptic technique due to high risk of
osteomyelitis
 Treat similar as IV administration
 Volumes, type of fluid, fluid rate
 Short term only

Question 7

Maintenance volumes

Answer 7

 The amount of water (fluid) intake required for basic functions in a healthy individual
 Some variation depending on source of information
 Varies with
 Species
 Size of animal
 Age (pediatric require more fluid)
 Health status (cardiac and renal most important

Question 8

Deciding rates and volumes

Answer 8

 The rate is an order by the DVM
 “Maintenance/pediatric/surgical/shock rate”
 “Replace % or mls dehydration”
 The total amount given is an order by the DVM
 Hours of therapy
 Total volume to be infused (VTBI)
 How it is administered is determined by the RVT
 Convert order to ml/h
 Convert to drip rate
 Start and stop times

Question 9

Prescribed rate

Answer 9

Fluid administration rate ordered by the DVM
 Expressed as ml/kg/h in small animals
 Expressed as L/kg/h in large animals

Question 10

Infusion rate

Answer 10

The rate at which fluids are administered
 Determined from prescribed rate
 Expressed as ml/h in small animals
 Expressed as L/h in large animals
 How rates are entered in the medical record

Question 11

Drip rate

Answer 11

The rate of fluid administration expressed as drops/sec or drops/min when using a drip-set
 Specific to the size of the drip-set being used
 Must be whole drops
 Not usually entered in the medical record

Question 12

Delivery rate

Answer 12

The number of calibrated drops of fluid that make up 1 ml of fluid
 Expressed as drops/ml
 Must be whole drops

Question 13

Infusion time

Answer 13

The total time over which fluids are administered
 Expressed in hours

Question 14

Volume infused

Answer 14

The total volume of fluid administered
 Expressed in mls or liters
 Infusion rate x infusion time
 Also “volume to be infused (VTBI)”, “infusion volume”

Question 15

IV drip administration

Answer 15

 Simplest form of IV fluid administration
 Uses gravity
 Supplies
 IV fluid bag (50 ml to 1 L, select based on patient size)
 IV infusion set (primary drip set)
 Extension set (optional*)
 Sterile needle
 Fluid stand
 Tape
 Permanent marker
 Clock or watch with second hand
 IV catheter in patient

Question 16

IV infusion set

Answer 16

 Primary drip set, drip set
 Macro (regular) size: 10, 15 or 20 drops/ml
 Micro (pediatric) size: 60 drops/ml
 Rough guideline
 Select a macro drip if >10 kg and/or >100 ml/h
 Select a micro drip is <10 kg and/or < 100 ml/h
 Easiest to count between 1 drop/sec to 1 drop/4 sec

Question 17

Troubleshooting fluid rates

Answer 17

 Roller clamp has variable quality/accuracy
 Long-term use wears plastic so flow rates may change
 Flow rate changes with any change in vertical distance between bag and patient; and with positioning of line
 Moving patient up or down
 Moving bag up or down
 Moving patient around
 Maximum flow rate is limited by the size of the infusion set AND the gauge of the IV catheter

Question 18

Moving a patient on IV fluids

Answer 18

 When using a drip set:
 Rate of flow is determined by difference in height between the fluid bag and the patient
 Height will change when patient is moving this will alter flow rate
 ALWAYS turn off fluids infusion when patient is being moved
 ALWAYS re-set and confirm drip rate when patient stops moving
 Moving a patient while fluids are running risks fluid overload

Question 19

Stopping fluid infusion

Answer 19

 Moving patient (moving from induction to OR; moving from OR to recovery); OR if no extension set
 Close slide clamps at 2 sites if possible:
1. Closest to patient
2. Closest to fluid bag
 Longer periods (bathroom, walks, x-ray) where patient is stable enough to be off fluids; and where there is an extension set
 Turn off flow
 Close slide clamps
1. Closest to patient
2. Closest to connector (on both sides of the connecter)
 Extension set stays with patient
 Disconnect and cap off both ends to maintain sterility
 Wrap extension set against patient’s leg with vetwrap
 When reconnecting the IV fluids, check catheter has not clotted or displaced
 Check by flushing

Question 20

Y-injection ports

Answer 20

 Where medication or other fluids can be injected to be infused into the patient
 Needle-ports
 Needle-free ports (clave connectors)
 ALWAYS wipe port with alcohol before each use

Question 21

IV push or bolus

Answer 21

 Giving a medication intravenously in one-shot (not over an extended period of time)
 Can inject medication into an injection port in the IV line
 Still given over 30 seconds up to 1 minute
 Dependent on volume to be given
 Decreases how quickly the drug reaches its peak concentration anywhere in the body
 This decreases risk of adverse drug effects:
 Toxicity
 Anaphylaxis
 Overdose
 Must flush line to get into patient

Question 22

Slow IV

Answer 22

 One-shot of medication given over 10 – 20 minutes
 These drugs have more toxicity so the goal is to prevent a sudden spike
 Toxic effects if given faster

Question 23

Infusion pump

Answer 23

 Aka volumetric pump
 Force fluid into the vein under pressure
 Does not depend on gravity
 Consistent, accurate
 Must enter infusion rate: ml/hr
 Range is usually 1 ml/h to 999 ml/h
 Note: takes 5 ml/h to keep vein open
 Some models have a VTBI – will turn off after desired volume infused
 Problems:
 Risk of infiltration if catheter displaces and forces fluid into tissues
 May not alarm if problems so must check regularly
 Occlusion = line is blocked or flow is blocked

Question 24

Volume controlled burette

Answer 24

 Gravity based
 Place between IV bag and patient
 Used for greater accuracy in
1. Measuring smaller volumes
2. Delivering medications
 100-150 ml chamber size
 1 ml increments
 Chamber filled to desired amount from primary bag
 Medication injected into port
 Desired rate set manually (drip chamber) or with pump
 Previous slide shows “flow-
through” set-up
 Photo on right shows proper
way to hang burette if full
VTBI is contained in burette
 Burette MUST be perpendicular
to ground

Question 25

Flow regulators

Answer 25

 Component that is part of an infusion set or can be added as an extension set
 Provides constant infusion rate to patient
 Works by controlling size of opening
 5 ml/hr to 250 ml/h
 Gravity sets only
 No drips to count
 Single use only

Question 26

Secondary IV

Answer 26

 Purpose:
 Increase the amount of reservoir fluids
 To deliver an intermittent medication or second type of fluid
 Each bag has its own drip chamber so can set independent flow rates
 Second bag of fluid is placed higher than the primary bag
 Higher bag will empty first, when it is done, primary bag will then flow
 Requires a specific piggy-back infusion set that connects with a Y-port

Question 27

In line filters

Answer 27

 Precision filters
 Openings as small as 0.2 μm
 Placed in-line
 Depending on type of filter, can remove air, particulate matter
 Blood transfusion sets have 160-270 μm filters to remove small clots and clumps due to storage

Question 28

Syringe pump

Answer 28

 Purpose: To deliver small volume of fluid (placed in the syringe) at a constant rate over given period of time
 Volume determined by size of syringe
 Used for
1. Medications that cannot be diluted into an IV bag
2. Fluid delivery into very small patients

Question 29

CRI

Answer 29

 Continuous rate infusion
 Dosing regiment used to deliver a constant amount of drug per unit time
 Usually ml/kg/hr; can be as little as microliters (μl) per min
 Most commonly by IV infusion
 Drip rate is an example
 Syringe pump delivery is an example
 Can also be by transdermal delivery (e.g., patches)

Question 30

After adding drug to an IV line

Answer 30

 After the medication has been administered, flush the line with 3-5 ml
of 0.9% saline or LRS (enough to clear the medication from the line).
Give at the same rate the medication was administered.
 Also need to flush a burette if using to administer a medication.
Volume should be at least 2x the amount of dead space in the tubing between the burette and the patient. Give at same rate as drug was administered.

Question 31

IV fluid types

Answer 31

 All IV fluids are solutions consisting of solutes that are dissolved in water
 Composition varies, but in general contain:
 Water
 One or more electrolytes
 Na+, Cl-, K+, Mg+
 Buffer to regulate pH
 lactate, bicarbonate, gluconate, acetate, phosphate
 Colloids – Large molecular weight molecules
 Dextrose for nutrition

Question 32

IV fluid classifications

Answer 32

Based on relation to osmotic pressure
 Isotonic – same osmolarity as plasma
 Hypotonic – significantly less osmotic pressure than plasma
 Fluid leaves veins and enters tissue
 Hypertonic – significantly greater osmotic pressure than plasma
 Fluid enters veins from tissue
 Balanced versus unbalanced
 Balanced fluids have a profile similar to extracellular fluid (ECF)
 High concentration Na+, Cl- and bicarbonate
 Unbalanced fluids - Profile is not similar to ECF

Question 33

IV fluids based on functional use

Answer 33

 Replacement fluids
 Higher levels Na+ and Cl-
 Intended for replacing lost body water or short-term use
 Maintenance fluids
 Lower Na+ and Cl-, higher K+
 Intended for long-term use
 Other – flush, hypertonic saline…

Question 34

IV fluids based on molecular weight

Answer 34

Crystalloid
Colloid
Blood and blood products

Question 35

Crystalloids

Answer 35

 Most common for maintenance and surgical fluids
 Physiological saline (0.9% NaCl) mostly for flushes, flushing wounds and body cavities, can be used for replacement
 LRS, Normosol, Plasmalyte, physiological saline with 20 mEq KCl

Question 36

Colloids

Answer 36

 Large molecular weight solutes that cannot cross out of blood
vessels
 Supports oncotic pressure; draws water out of interstitial space
and into blood vessels
 Only used if crystalloids are not sufficient to maintain BP
 Fluid selection is up to the VIC; based on each patient
 Must record fluid type, rate, total volume (or start and stop times), any changes in fluid rate as they occur

Question 37

Crystalloids are

Answer 37

 Water + small molecular weight solutes
 Electrolytes
 Na+, Cl-, K+, Ca+, Mg+
 Very high levels of Cl- compared to plasma
 Buffers
 phosphate, lactate, bicarbonate, acetate, gluconate
 +/- Dextrose
 Molecules are small enough to pass in and out of the blood vessels
 Generally used for flushing, replacement and maintenance
 Often used in anesthesia patients
 Unless they are anemic or have severe hypotension
 5 basic types of crystalloid

Question 38

Replacement solutions

Answer 38

 Isotonic - Osmolarity similar to plasma
 Polyionic - Contains multiple electrolytes and buffers
 Balanced – Similar to ECF
 Indicated for restoring hydration, correcting hypotension, replacing
electrolytes
 Can be used for short-term maintenance
 Need to check electrolytes q24h
 Reminder: high in Na+ and Cl-; low in K+
 Common examples
 Lactated Ringer’s Solution* (LRS)
 Normosol-R (NR)
 PlasmaLyte A and R* (PA and PR)
 Isolyte S (IS)
* LRS and PR contain
calcium and cannot
be administered
with blood products

Question 39

Maintenance solutions

Answer 39

 Compared to replacement solutions:
 Contain less Na+, less Cl-
 Contain more K+
 Contain lower concentrations of buffers
 May contain dextrose
 Indicated for long-term use
 Unlike replacement fluids, will not cause hypernatremia and hypokalemia over time
 Common examples
 Normosol-M (NM)
 PlasmaLyte 56 (PL56)

Question 40

Dextrose containing solutions

Answer 40

 Maintenance solutions may contain dextrose
 Commonly available as 5% solution (5g/100 mL)
 Can also purchase as 50% w/v solution in water to add to an IV bag
 Only give dextrose solutions IV
 Indicated for parenteral nutrition
 Hypoglycemia, neonates, diabetics, severely debilitated (cachexic)
 Common examples
 LRS + 5% dextrose (D5LR)
 Plasma-Lyte 56 with 5% dextrose (PL56D5)

Question 41

Normal saline

Answer 41

 Physiologic saline, 0.9% saline, NaCl 0.9%
 Only contains sodium and chloride
dissolved in water
 Isotonic, buffered to physiologic pH
 Indicated for
 Flushing IV catheters
 Flushing wounds
 Bathing tissues or body cavities during
surgery
 Sometimes used in place of replacement solutions – may require addition of potassium

Question 42

Hypertonic saline

Answer 42

 Concentrated NaCl solution – 3%, 5%, 7% and 23.4%
 Injection into vein creates very large osmotic gradient
 Water moves from ECF into the intravascular space
 Indicated for
 Severe hyponatremia
 Managing severe hemorrhage or hemorrhagic shock
 Fast-acting, low-volume resuscitation (hypovolemic shock)
 Treating high intracranial pressure
 Contraindicated in hypernatremia, severe dehydration
 Seldom used

Question 43

Colloids are

Answer 43

 Contain large molecular weight solutes
 Usually starch molecules too big to leave the blood vessels
 Molecules increase oncotic pressure in blood vessels
 Draw water into vessels
 Indicated for
 Hypotension and large volume losses (when crystalloids are not enough)
 Low total protein (TP < 35 g/L)
 Examples of synthetic colloids:
 Hetastarch
 Dextran

Question 44

Blood and blood products

Answer 44

 Includes whole blood, RBC concentrate, platelet extract, plasma
 Plasma contains albumin which is considered a “natural colloid”
 Indication depends on type of product being used
 Hemorrhage
 Anemia
 Bleeding disorders
 Hypoproteinemia
 Very expensive, can be hard to access, risk of adverse reaction

Question 45

Volume overload

Answer 45

 Aka over-hydration
 Can occur from too much fluids OR too fast fluids
 Giving fluids too fast prevents them from entering into
the extracellular fluid volume properly
 Physiological effects of volume overload
 Hypertension
 Very bad if pre-existing heart disease; causes heart to
work harder and can cause cardiac overload
 Fluids move to 3rd spaces in the body
 Abdomen, pleural space, pulmonary spaces
 Most common is pulmonary edema
 Can also cause cerebral edema
 Can dilute oxygen carrying capacity of blood

Question 46

Signs of volume overload

Answer 46

 Increased lung sounds and respiratory rate
 Dyspnea
 Coughing and restlessness if patient is awake
 Tachycardia – why?
 Increased BP
 Hemodilution (decrease the relative PCV)
 Ocular and nasal discharge
 Chemosis
 Subcutaneous edema
 Neurological signs
Response to volume overload
1. Reduce infusion rate
2. Give diuretics
* Furosemide given IV acts in 5 minutes
* Causes diuresis (i.e., promotes urination)

Question 47

Who is most at risk for volume overload

Answer 47

Most at risk for volume overload:
 Cardiovascular patients
 HCM, heart failure, mitral valve insufficiency, hypertension
 Renal failure patients
 Patients <5 kg
 Patients that are already anemic
 Can affect the oxygen carrying capacity of the blood
 Patients that are hypoproteinemic
 Already have lower oncotic pressure
 So fluid more likely to leave the blood vessels

Question 48

Preventing volume overload

Answer 48

 Know your calculations!
 Use an appropriate-sized fluid bag
 ex. 100 ml for cat spay
 Clamp off the line when transporting patients
 Check IV line and rate hourly
 Caution: most drip sets will alter their rate
slowly over time
 Use an infusion pump
 Monitor equipment
 Monitor patient
 Use IV fluids when monitored and SQ fluids if
not monitored