LMH ER Rounds September 22, 2015

Prepared by Shane Barclay

FLUID RESUSCITATIONIN THE ER

Review flow rates through different IV

Review types of access for fluids – IV and IO

Review types of IV solution

In the simulation, we will be concentrating on practicing using the new IV sets and using the EZ-IO drill and the FASTresponder Intraosseous device.

OBJECTIVES

Flow rate is related to the diameter and the length of the cannula as well as the pressure exerted.

As we all remember !: Flow is inversely proportional to the 4th power of the radius [Pouseuille's law] - i.e. small changes in cannula diameter = large changes in flow.

Therefore a large IV that is long, may actually have a slower rate than a smaller but shorter caliber IV cannula.

FLOW RATES THROUGH DIFFERENT IV CANNULA

A large bore cannula is preferable to a narrow bore cannula.

A shorter cannula is preferable to a longer cannula.

A larger proximal vein is preferable to smaller distal vein.

Upper limbs are preferable to lower limbs, especially in. cardiac arrest.

GENERAL RULES OF THUMB

Gravity Flow Rate

ml/min

Time in minutes to

Infuse 1 liter

Time in minutes to

Infuse 1 liter with pressure

bag

20 G 25mm 65 15 9.5

18 G 32 mm 104 9.6 6.5

16 G 32mm 220 4.5 2.8

14G 32mm 302 3.3 2.0

Syringe push

250 4

IV pump 16 63

FLOW RATES WITH DIFFERENT IV CATHETERS

• A peripheral cannula of size 18G or greater is preferable to infusion by central line for rapid fluid delivery. Remember a central line is ‘longer’.

• For any critically ill patient, hand IVs should be avoided. Try to obtain antecubital fossa veins.

• If after 2 IV attempts no success, tell the team leader and he/she should consider an intraosseous access.

CHOICE OF VASCULAR ACCESS

Flow rates of 60–100 ml/min of crystalloid, via a 15 gauge tibial intraosseous needle, have been achieved in the adult using the hydraulic pressure of a large syringe.

In a resuscitation setting, IO access is preferable to CVP insertion if peripheral vascular access cannot be obtained rapidly— higher success rates on first attempt (85% versus 60%)— shorter procedure times (2.0 versus 8.0 min)

INTRAOSSEOUS ACCESS

TYPES OF INTRAOSSEOUS DEVICES

FastResponder Sternal IO

EZ-IO Drill

TYPES OF INTRAOSSEOUS DEVICES

• Videos demonstrating both the FASTResponder Sternal intraosseous and the EZ IO drill device can be viewed as separate videos on the LMHER web page.

There are:

Crystalloids (Normal saline, Ringer’s) and

Colloids (Pentaspan, Hextend..)

Randomized clinical trials comparing crystalloids versus colloids have found NO advantage of one over the other. Colloids however are much more expensive.

SELECTION OF IV FLUID

MAKEUP OF DIFFERENT IV SOLUTIONS

Na Cl K Ca Lactate Calories pH

D5W - - - - - 170 4

D5/NS 154 154 - - - 170 ~5

N/S 154 154 - - - - ~5

2/3-1/3 270 51 - - - - ~6

R/L 130 109 4 2.7 28 * 9 ~6.5

* Na lactate, not Hydrogen lactate

Was introduced in 1930s when sodium was added as a buffer to aid treatment of metabolic acidosis (which occurs in severe hemorrhage and trauma)

It is also closer to ‘normal pH’ then normal saline so is often preferred in large volume resuscitation.

However calcium can bind some medications as well as the citrated anticoagulant in blood, so is not the ideal for transfusion patients.

It is also slightly more isotonic than normal saline and therefore should not be used where plasma osmolality is important – ie acute brain injury.

RINGER’S LACTATE

1 liter of N/S will distribute ~ 250 ml into the vascular compartment (thus the 3:1 rule of resuscitation 3 parts IV solution for every 1 part blood loss)

However the 3:1 rule is often not accurate and may be as much as 7:1 or even 10:1.

This is due to decreased colloid oncotic pressure, capillary leak and crystalloid replacement that can occur in major hemorrhage.

NORMAL SALINE

Normal saline supplies supra-physiologic sodium and chloride which is useful for retaining intravascular volume and in patients with metabolic alkalosis (ie vomiting, diarrhea, GI obstruction).

But in large volumes, N/S can induce hyperchloremic metabolic acidosis.

NORMAL SALINE

Ideally, the source of hypovolemia, electrolyte abnormalities and the actual volume replacement required should aid in fluid selection.

However, IV fluid selection is not as important as the amount of IV fluids given to an appropriate therapeutic end point.

Bottom line: neither Ringer’s nor Normal Saline have shown superiority in clinical trials.

SO.. RINGERS OR NORMAL SALINE ?

So all the previous being said, the old ATLS guidelines used to recommend 2 liters of IV fluid followed by BP assessment and then if needed more IV fluids.

The latest ATLS guidelines now say that in trauma, give 1 liter of IV fluid, and if no normalization of BP, give blood products.

This negates a lot of the issues of what to give for IV fluids in trauma!

THIS MAY ALL BE IRRELEVANT IN TRAUMA PATIENTS

All critically ill patients, all trauma patients and any patient suspected of being hypovolemic needs IV therapy.

The challenge is how much and of what.

The topic of ‘shock’ will be dealt with in a separate rounds.

The topic of fluid assessment will also be dealt with in a separate rounds topic.

WHEN DO PATIENTS NEED FLUID THERAPY?