Fluid Resuscitation in the ER

1. Fluid Resuscitationin the ER Prepared by Shane Barclay MD

2. Discloser This presentation does not cover all types of IV fluids many of which are used in prolonged IV fluid replacement scenarios. Rather it centers on immediate fluid resuscitation in the ER.

3. Objectives Review flow rates through different IVs Review types of access for fluids – IV and IO Review types of IV solution Review Fluid Resuscitation specifically in Shock

4. Flow rates through different IV cannula 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.

5. General Rules of thumb 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 or shock.

6. Flow Rates with different IV catheters

7. Choice of vascular access A peripheral cannula of size 18G or larger is preferable to infusion by central line for rapid fluid delivery. 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 intraosseous.

8. Intraosseous access 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) For more in depth review of IO devices see web page on REMSTAR.ca entitled “Intraosseous Devices”

9. Types of intraosseous devices FastResponder Sternal IO EZ-IO Drill

10. Selection of IV fluid 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.

11. 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

12. Ringer’s 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.

13. Normal Saline 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.

14. 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.

15. So.. ringers or Normal Saline ? Ideally, the source of hypovolemia, electrolyte abnormalities and the actual volume replacement required should aid in fluid selection. 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 major superiority in clinical trials for resuscitation. But Ringer’s seems to be coming back as the fluid of choice.

16. So.. ringers or Normal Saline ? Or a more pertinent question is when do you stop IV fluids and go to packed red cells? The ‘dictum’ used to be to give 2 liters of IV fluids first in trauma and if no change in pressure etc, then give packed red cells. That view is changing and going to red cells much earlier particularly in obvious hypovolemic trauma cases.

17. Fluid resuscitation in shock Some general principles

18. Shock Shock is defined a state of inadequate tissue perfusion. This does not equal ‘perfusion pressure’ Thus blood pressure is not a reliable indicator of adequate oxygen delivery to tissues, nor perfusion. Shock can occur in patients with normal or even elevated blood pressure. Inadequate tissue perfusion in the setting of normotension is called ‘compensated shock’.

19. Shock Decompensated shock on the other hand is a late sign of shock. MAP of < 65 or a Systolic < 90 mm Hg should raise concerns of hypotension even in the absence of overt clinical hypotension. Brief, self limited episodes of hypotension represent depletion of CV compensation and are the first signs of decompensated shock. Remember, automated BP cuffs can overestimate BP in low flow states. As well, direct auscultation can underestimate SBP by as much as 30 mm Hg in low flow states.

20. Shock – Classes I - IV % blood loss blood loss Signs I < 15% <750 mls none, + HR II 15 – 30 % 750 – 1500 ml HR, RR, no syst. change III 30 – 40 % 1500 – 2000 ml HR, RR, Syst BP, PPres IV > 40 % > 2000 ml HR, RR PPres Syst BP, + no Dias BP Importance of serial vital monitoring.

21. IV access As covered in previous slides Points to remember: - flow is related to diameter and length of the IV - doubling the catheter size increases flow by 16 fold, whereas doubling cannula length decreases flow by half. - use large short IV in the antecubital veins, with pressure bags.

22. END point of resuscitation Traditionally restoration of systolic BP or a MAP of 60-65 was considered an end point. Recent data suggests such end points don’t necessarily guarantee optimal organ perfusion. Serum lactate helps predict morbidity and mortality independent of hemodynamics. Lactate clearance can be reassuring that resuscitation efforts are being successful. However no optimal end point of resuscitation is currently available.

23. END point of resuscitation Historically the rule of 3:1 (3 units of volume for every 1 unit lost in hemorrhage) was taught. However experimental models of severe hemorrhage/hypotension show that the 3:1 rule is often quite inadequate. Also, CVP measurement is an unreliable predictor of fluid status, preload or response to fluid therapy. Although not exact, respiratory collapse of the inferior vena cava greater than 50% can be a helpful and easily identified sign in the rural setting with ultrasound, that the patient is volume depleted.

24. END point of resuscitation Passive leg raising. Volume responsive patients respond to passive leg raising of 3 minutes, with a temporary improvement in stroke volume greater than 15%. However stroke volume measurement is not available in rural settings so not of much value. If BP does go up that can be an indicator or response however.

25. Summary Even a transient drop in BP can signal significant hypotension and is associated with poorer outcomes. Be systematic in examination and the approach to shock. IV Normal Saline should be provided to virtually all ER critically ill patients. Be familiar with pressor agents. Goal is to achieve a MAP of at least 65 mm Hg. However even a MAP of 65 does not ensure adequate organ perfusion. Lactate clearance is one marker of favorable resuscitation.

26. Questions?