Introduction to IV Therapy

1
Introduction to IV Therapy

• A Brief Guide Summation
• Jackie Weisbein, D.O.
• Westchester General Hospital
• Miami, Florida

2
Aims Objectives

• By the end of this lecture, it is my hope that
  you are all able to
• Differentiate the gauges of IV needles/catheters
• Differentiate IV fluids available
• Differentiate between IVFs re side effects
  applications
• How to prescribe IVF
• How to calculate the rate of an IV drip

3
Indications for IV Therapy

• Establish or maintain a fluid or electrolyte
  balance
• Administer continuous or intermittent medication
• Administer bolus medication
• Administer fluid to keep vein open (KVO) (Old
  Skool!)
• Administer blood or blood components
• Administer intravenous anesthetics
• Maintain or correct a patient's nutritional state
  
• Administer diagnostic reagents
• Monitor hemodynamic functions

4
Types of IV Needles

• Steel needles Butterfly catheters, named for the
  plastic tabs that look like wings. Used for small
  quantities of medicine, infants, and to draw
  blood although the small size of the catheter can
  damage blood cells. Usually small gauge needles.
• Over-the-needle catheters Peripheral-IV
  catheters are usually made of various types of
  Teflon or silicone materials which determines how
  long the catheter can remain in your vein. These
  typically need to be replaced about every 1 to 3
  days.
• Inside-the-needle catheters Larger than
  Over-the-needle catheters, typically used for
  central lines.

5
Gauges

• Needles Catheters are sized by diameters which
  are called gauges.
• Smaller diameter larger gauge
• IE 22-gauge catheter is smaller than a 14-gauge
• Larger diameter more fluid able to be delivered
• If you need to deliver a large amount of fluid,
  typically 14- or 16-gauge catheters are used.

6
Types of IV Fluids

• Three main types of IVF
• Isotonic fluids
• Hypotonic fluids
• Hypertonic Fluids

7
Isotonic Fluids

• Osmolarity is similar to that of serum.
• These fluids remain intravascularly mommentarily,
  thus expanding the volume.
• Helpful with patients who are hypotensive or
  hypovolemic.
• Risk of fluid overloading exists. Therefore, be
  careful in patients with left ventricular
  dysfunction, history of CHF or hypertension.
• Avoid volume hyperexpansion in patients with
  intracranial pathology or space occupying
  lesions.

8
Hypotonic Fluids

• Less osmolarity than serum (meaning in general
  less sodium ion concentration than serum)
• These fluids DILUTE serum thus decreasing
  osmolarity.
• Water moves from the vascular compartment into
  the interstitial fluid compartment ? interstitial
  fluid becomes diluted ?osmolarity descreases ?
  water is drawn into adjacent cells.
• These are helpful when cells are dehydrated from
  conditions or treatments such as dialysis or
  diuretics or patients with DKA (high serum
  glucose causes fluid to move out of the cells
  into the vascular and interstitial compartments).
• Caution with use because sudden fluid shifts from
  the intravascular space to cells can cause
  cardiovascular collapse and increased ICP in
  certain patients.

9
Hypertonic Fluids

• These have a higher osmolarity than serum.
• These fluids pull fluid and sometimes
  electrolytes from the intracellular/interstitial
  compartments into the intravascular compartments.
• Useful for stabilizing blood pressure, increasing
  urine output, correcting hypotonic hyponatremia
  and decreasing edema.
• These can be dangerous in the setting of cell
  dehydration.

10
Two Main Groups of Fluids

• Crystalloids
• Colloids

11
Crystalloids

• Clear solutions fluids- made up of water
  electrolyte solutions small molecules.
• These fluids are good for volume expansion.
• However, both water electrolytes will cross a
  semi-permeable membrane into the interstitial
  space and achieve equilibrium in 2-3 hours.
• Remember 3mL of isotonic crystalloid solution
  are needed to replace 1mL of patient blood.
• This is because approximately 2/3rds of the
  solution will leave the vascular space in approx.
  1 hour.
• In the management of hemorrhage, initial
  replacement should not exceed 3L before you start
  using whole blood because of risk of edema,
  especially pulmonary edema.

12
Crystalloids Continued

• Some of the advantages of crystalloids are that
  they are inexpensive, easy to store with long
  shelf life, readily available with a very low
  incidence of adverse reactions, and there are a
  variety of formulations that are available that
  are effective for use as replacement fluids or
  maintenance fluids.
• A major disadvantage is that it takes
  approximately 2-3 x volume of a crystalloid to
  cause the same intravascular expansion as a
  single volume of colloid.

13
Colloids

• Colloids are large molecular weight solutions
  (nominally MW gt 30,000 daltons)gt These solutes
  are macormolecular substances made of gelatinous
  solutions which have particles suspended in
  solution and do NOT readily cross semi-permeable
  membranes or form sediments.
• Because of their high osmolarities, these are
  important in capillary fluid dynamics because
  they are the only constituents which are
  effective at exerting an osmotic force across the
  wall of the capillaries.
• These work well in reducing edema because they
  draw fluid from the interstitial and
  intracellular compartments into the vascular
  compartments.
• Initially these fluids stay almost entirely in
  the intravascular space for a prolonged period
  of time compared to crystalloids.
• These will leak out of the intravascular space
  when the capillary permeability is deranged or
  leaky.

14
Colloids Continued

• Albumin solutions are available for use as
  colloids for volume expansion in the setting of
  CHF however albumin is in short supply right now.
• There are other solutions containing artificial
  colloids available.
• The general problems with colloid solutions are
• Much higher cost than crystalloid solutions
• Small but significant incidence of adverse
  reactions
• Because of gelatinous properties, these can cause
  platelet dysfunction and interfere with
  fibrinolysis and coagulation factors thus
  possibly causing coagulopathy in large volumes.
• These fluids can cause dramatic fluid shifts
  which can be dangerous if they are not
  administered in a controlled setting.

15
Crystalloids Saline Solutions

• 0.9 Normal Saline Basically Salt and Water
• Principal fluid used for IV resuscitation and
  replacement of salt loss e.g V/D
• Contains Na 154 mmol/l, K - Nil, Cl- - 154
  mmol/l But K is often added
• ISOOsmolar compared to normal plasma
• Distribution Stays almost entirely in the
  Extracellular space
• Of 1 liter ? approx 750ml stays
  Extracellular fluid 250ml moves Intravascular
  fluid
• So for 100ml blood loss ? need to give 300-400ml
  NSonly ¼-1/3 remains intravascular
• 0.45 Normal saline Half Normal Saline
  HYPOtonic saline
• Can be used in severe hyperosmolar states E.g.
  H.O.N.K and dehydration
• Leads to HYPOnatraemia if plasma sodium is normal
  (dilution if unchecked)
• May cause rapid reduction in serum sodium if used
  in excess or infused too rapidly. This may lead
  to cerebral oedema and rarely, central pontine
  demyelinosis Use with caution!
• 1.8, 3.0, 7.0, 7.5 and 10 Saline HYPERtonic
  saline
• Reserved for plasma expansion with colloids or
  acute hyponatrema
• In practice rarely used in general wards
  Reserved for high dependency, specialist areas
• Distributed almost entirely in the ECF and
  intravascular space? an osmotic gradient between
  the ECF and ICF?passage of fluid into the EC
  space.
• This fluid distributes itself evenly across the
  ECF and intravascualr space, in turn leading to
  intravascular repletion.
• Large volumes will cause HYPERnatraemia and IC
  dehydration.

16
Crystalloids Dextrose Solutions

• 5 Dextrose (often written D5W) Sugar and
  Water
• Primarily used to maintain water balance in
  patients who are not able to take anything by
  mouth Commonly used post-operatively in
  conjuction with salt retaining fluids ie saline
  Often prescribed as 2L D5W 1L N.Saline
  Physiological replacement of water and Na
  losses
• Provides some calories approximately 10 of
  daily requirements
• Regarded as electrolyte free contains NO
  Sodium, Potassium, Chloride or Calcium
• Distribution lt10 Intravascular gt 66
  intracellular
• When infused, is rapidly redistributed into the
  intracellular space Less than 10 stays in the
  intravascular space therefore it is of limited
  use in fluid resuscitation.
• For every 100ml blood loss need 1000ml dextrose
  replacement 10 retained in intravascular space
• Common cause of iatrogenic hyponatraemia in
  surgical patient
• Dextrose saline Think of it as a bit of salt
  and sugar
• Similar indications to 5 dextrose Provides Na
  30mmol/l and Cl- 30mmol/l Ie a sprinkling of salt
  and sugar!
• Primarily used to replace water losses
  post-operatively
• Limited indications outside of post-operative
  replacement Neither really saline or
  dextrose Advantage doesnt commonly cause
  water or salt overload.

17
What The _at_!? Does That Mean?

• H2O is the most abundant constituent in the body,
  comprising approx 50 of body weight in women and
  60 in men (difference relative to adipose
  tissue).
• Total body water is distributed to two major
  compartments 55-75 ICF and 25-45 ECF (which is
  intravascular and extravascular in a ration of
  13)
• Water balance is maintained by plasma osmolality
  (solute or particle concentration of a fluid) and
  the normal range is 275 to 290 mosmol/kg and is
  VERY sensitive.
• To maintain a steady state, water intake must
  equal water excretion.
• Obligate water losses urine, stool (minor
  component), evaporation of from skin
  respiratory tract (insensitive losses).

18
Urine Water Losses

• Obligatory renal H2O loss is mandated by the
  minimum solute excretion required to maintain a
  steady state.
• On average, approximately 600 mosomols must be
  excreted per day.
• Since the maximum urine osmolality is 1200
  mosmol/kg, a minimum urine output of 500 mL/d is
  required to maintain a neutral solute balance.

19
Hypovolemia

• True volume depletion, or hypovolemia, usually
  refers to a state of combined salt and water loss
  exceeding intake which leads to ECF volume
  contraction. The loss of sodium may be renal or
  extrarenal.
• ECF volume contraction is manifested as a
  decreased plasma volume and hypotension.
• Signs of intravascular volume contraction include
  decreased jugular venous pressure, postural
  hypotension, and postural tachycardia.
• Larger and more acute fluid losses lead to
  hypovolemic shock and manifest as hypotension,
  tachycardia, peripheral vasoconstriction,
  hypoperfusion.

20
Hypovolemia Etiologies With ECF Volume Contraction

• Extrarenal Na Losses
• GI vomiting, NG suction, drainage, fistual,
  diarrhea
• Skin/Respiratory insensible losses, sweat, burns
• Hemorrhage
• Renal Na and H2O Losses
• Diuretics
• Osmotic Diuresis
• Hypoaldosteronism
• Salt-wasting Nephropathies
• Renal Water Loss
• Diabetes Insipidus (central or nephrogenic)

21
Hypovolemia Etiologies With ECF Volume Normal or
Expanded

• Decreased Cardiac Output
• Myocardial, Valvular or Pericardial Disease
• Redistribution
• Hypoalbuminemia hepatic, cirrhosis, nephrotic
  syndrome
• Capillary Leak acute pancreatitis, ischemic
  bowl, rhabdomyolysis
• Increased Venous Capacitance
• Sepsis

22
Treatment of Hypovolemia

• The goals of treatment is to restore normovolemia
  with fluid similar in composition to that lost
  and replace ongoing losses.
• Mild volume losses can be corrected via oral
  rout.
• More severe hypovolemia requires IV therapy.
• Isotonic or Normal Saline (0.9NaCl) is the
  solution of choice in normonatremic and mildly
  hyponatremic patients and should be administered
  initially in patients with hypotension or shock.
• Severe hyponatremia may require Hypertonic Saline
  (3.0 NaCl)

23
Hypovolemia Treatment Continued

• In the Hypernatremic patient, there is a
  proportionately greater deficit of water than
  sodium, therefore to correct this patient you
  will use a Hypotonic solution like ½ NS (0.45
  NaCl) of D5W.
• Patients with significant hemorrhage, anemia, or
  intravascular volume depletion may require blood
  transfusions or colloids (albumin/dextran).
• Hypokalemia can be simultaneously corrected by
  adding appropriate amounts of KCl to replacement
  solutions.

24
Approach to IVF in the Medical Pt

• First lets review the equation for estimating
  serum osmolalitySerum osmolality 2 (Na)
  Glucose/18 BUN/2.8
• See how much more sodium adds to your osmolality
  then glucose does?
• Thats why D5 ½NS is inappropriate for most
  medical patients who are hypovolemic.
• They need isotonic fluids (normal saline).
• Also, remember that dextrose gets almost
  immediately metabolized to water and CO2 when it
  enters the circulation so it is not osmotically
  active for too long.

25
The 4 Types of Patients

• When considering appropriate IV fluids as you are
  writing admission order, keep in mind that in
  general, there are 4 types of medical patients
  when it comes to administering IV fluids
• Hypovolemic Patient
• Pneumonia, Sepsis, Hemorrhage, Gastroenteritis
• Hypervolemic Patient
• CHF, renal failure, cirrohsis
• NPO Patient, surgical patient, euvolemic
• Awaiting surgery, unsafe swallow
• Eating/drinking normally

26
Determining Appropriate IVF

• Step 1 Assess volume status
• What is the volume status of my patient?
• Do they have ongoing losses?
• Can my patient take PO safely?
• Are the NPO for a reason?
• Step 2 Determine Access
• Peripheral IV
• Central line
• IO line

27
Determining Continued

• Step 3 Select Type of Fluid

28
Determining Continued

• Hypovolemic Patient
• Always use Normal Saline for goal of volume
  resuscitation
• Normal saline is almost isotonic with blood so
  it is the best choice!
• On surgery or if going to administer more than
  3-4L often use LR. (Addition of lactate that is
  metabolized to bicarbonate to help buffer
  acidosis)
• Hypervolemic Patient
• Avoid additional IVF
• Maintain access IV access with HepLock
• NPO Patient now euvolemic
• Administer maintenance fluids. Goal is to
  maintain input of fluids to keep up with ongoing
  losses and normal fluid needs
• For average adult NPO for more than 6-12 hours,
  consider D51/2NS at 75-100cc/hr
• Consider pt co-morbidities
• Constantly reassess, at least 2x day or with any
  change
• Dont give fluids blindly ie if the patient is
  pre-procedure but is old (predisposed to fluid
  overload because of stiff LV) or has history of
  CHF, be CAREFUL!
• Pearl the reason for giving dextrose (D5) is to
  prevent catabolism.
• Daily I/Os, watch lytes
• Normal PO Intake
• No need for fluids if they are taking PO without
  problems!
• Avoid IVF

29
Determining Continued

• Step 4 Determine Rate
• In medical patients, the rate is always a
  ballpark and you have to use your clinical
  judgement. (Not applicable for PEDS!)
• If you are trying to fluid resuscitate that
  patient, you might be giving fluids wide open
  or 500 cc/hr.
• The hypovolemic pt may need multiple 1L bolus to
  reestablish intravascular volume
• If you are just giving fluids to the average
  patient, give fluids at 75-100 cc/hr. Adjust for
  individual patient

30
Holiday Segar Method

• A peds method that can be helpful

• So a quick example
• For a 55 kg patient, the maintenance IV fluid
  rate would be 410 210 351 95 mL/hour.

31
Good Formulas to Remember

• For The Hypernatremic Patient STOP THE ONGOING
  LOSS!
• To Calculate Water Deficit
• Estimate TBW 50-60 body weight (KG) depending
  on body composition (W vs M)
• Calculate Free-Water deficit (Na - 140)/140 x
  TBW
• Administer deficit over 48-72 hrs
• Ongoing Water Losses
• Calculate Free-Water clearance from urinary flow
  rate (V) and urine (U) Na K concentrations
• V V x (UNa UK)/140
• Insensible Losses
• Approximately 10mL/kg per day less if
  ventilated, more if febrile.
• Total
• Add above components to determine fluid
  administration rate (typically approximately
  50-250 mL/h)

32
More Pearls!

• Correcting the Hyponatremic Patient
• You want to raise plasma sodium by restricting
  water intake promoting water loss
• And to correct the underlying disorder!
• Rate of Correction
• Rate should be slow (approximately 0.5 mmol/L per
  hour of Na)
• Rule of Thumb limit change in mmol/L of Na to ½
  the total difference within the first 24 hours.
• More rapid correction is associated with central
  pontine myelinolysis!
• Reserve hypertonic solutions for patients with
  SEVERE hyponatremia and ongoing neurologic
  compromise (ie patients with Na lt105 mmol/L in
  status epilepticus)
• Then you can raise it at a rate of 1-2 mmol/L pre
  hour for the first 3-4 hours or until the
  seizures stop but really no more than 12 mmol/L
  for the first 24 hours.

33
Hyponatremia Pearls Continued

• Normal TBW is 50-60
• So for a 70kg male, if we wanted to raise the
  Na concentration from 105 to 115 mmol/L
• (115 105) x 70 X 0.6
• which means we require 420 mmol for this patient

34
Calculating Drip Rate

• In the age of machines, we barely have to do this
  anymore but if you ever need to go old skool,
  here is how to calculate the drip rate
  (drops/minute)
• gtt Volume to be infused (mL) x (gtt/mL)
• min Time (minutes)
• Drip Factor (gtt/mL) Of the TUBING which is
  found on the manufacturers pacakging
• Example Volume 4000 ml
• Time 24 hours
• Drip factor of tubing 15 gtt/ml.
• So. 4000mL/(24h x 60min/h) X 15gtt/ml approx
  42 drops/min

35
Sources

• Harrison's principles of internal medicine, 16th
  ed. New York (NY) The McGraw-Hill Companies,
  Inc. c2004-2005. Hypovolemia
• Harrison's manual of medicine, 16th ed. New York
  (NY) The McGraw-Hill Companies, Inc.
  c2004-2005. Hypo/Hypernatremia
• Steve Martins Intravenous Therapy
  http//www.touchbriefings.com/pdf/14/ACF7977.PDF
• Browns Department of Family Medicine Adult IVF
  Handout http//www.geocities.com/brownfamilymed/
• Queen Marys School of Medicine Dentistry
  Prescribing Skills http//www.smd.qmul.ac.uk/presc
  ribeskills/
• Pharmacology Math http//www.accd.edu/sac/nursing
  /math/ivprob.html